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1

Reaction of yttrium polonides with carbon dioxide  

Microsoft Academic Search

It has been proved that heating of yttrium and tantalum in carbon dioxide to 500 and 800°C alters the gas phase composition, causing formation of carbon monoxide and reduction of oxygen content. A study of the thermal stability of yttrium polonides in carbon dioxide showed that yttrium sesqui- and monopolonides decompose at 400-430°C. The temperature dependence of the vapor pressure

A. S. Abakumov; A. D. Khokhlov; N. F. Reznikova

1986-01-01

2

Yttrium oxide nanopowders from carbonate precursors  

Microsoft Academic Search

Reactions of solutions of yttrium oxide in nitric acid with a 1.67 M NH4HCO3 solution were studied by direct and back titration. When the concentration of the reacting solution was within 0.0310.052\\u000a mol\\/L (as Y2O3), yttrium carbonate Y2(CO3)3 nH2O (n ? 2.5) of fibrous or spherulitic morphology precipitated. When the concentration was decreased to 0.022 mol\\/L, a new phase

P. P. Fedorov; E. A. Tkachenko; S. V. Kuznetsov; V. V. Voronov; V. V. Osiko; K. S. Samarina; N. I. Batyrev; I. V. Gontar; V. K. Ivanov

2010-01-01

3

Yttrium implantation effect on low manganesecarbon steel  

Microsoft Academic Search

Low manganesecarbon steels were implanted with yttrium using the ion implantation method. Compositional and structural analyses were carried out before and after yttrium implantation by several techniques such as Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction and glancing angle X-ray diffraction to observe the yttrium implantation effect on low manganesecarbon steel.

E Caudron; H Buscail; V. A. C Haanapel; Y. P Jacob; M. F Stroosnijder

2000-01-01

4

Vaporization Thermodynamics of Yttrium DicarbideCarbon System and Dissociation Energy of Yttrium Dicarbide and Tetracarbide  

Microsoft Academic Search

The Knudsen effusion method was used in conjunction with a double-focusing mass spectrometer to study the vaporization of the yttrium dicarbidecarbon system. Over the temperature range from 2270 to 2550K the measured vapor pressures for yttrium, yttrium dicarbide, and yttrium tetracarbide were found to be log10PY = (? 2.423 104 ? T) + 9.45, log10PYC2 = (? 3.286

Fred J. Kohl; Carl A. Stearns

1970-01-01

5

Thermal Decomposition of Lanthanide, Yttrium, and Scandium Oxalates and Carbonates  

Microsoft Academic Search

Data concerning the thermal decomposition of lanthanide, yttrium, and scandium oxalates and carbonates are surveyed. The complexity of the process, the large number of stages involved, and the dependence of the composition of the intermediates in the thermal transformations on the experimental conditions is noted. Certain process characteristics have been discovered and it is concluded that the decomposition process depends

Vyacheslav A. Sharov; G. V. Bezdenezhnykh

1981-01-01

6

Deposition of yttrium oxide thin films in supercritical carbon dioxide  

Microsoft Academic Search

A synthetic avenue for the formation of yttrium oxide thin films on Si native oxide surfaces is demonstrated by the reaction of Tris(2,2,6,6-tetramethyl-3,5-heptanedionato) yttrium(III) with inorganic (H2O2) and organic (tert-butyl and di-tert-amyl) peroxides in supercritical carbon dioxide. The reactions are carried out in a hot wall reactor at temperatures below 130C and pressures ranging from 13.10 to 22.75MPa. Spectroscopic Ellipsometry

Theodosia Gougousi; Zhiying Chen

2008-01-01

7

RBS and GAXRD Contributions to Yttrium Implanted Extra Low Carbon Steel Characterization  

Microsoft Academic Search

Extra low carbon steel samples were yttrium implanted using an ion implantation method. Composition and structural studies were carried out before and after yttrium implantations by several analytical and structural techniques (Rutherford backscattering spectrometry, reflection high energy electron diffraction, scanning electron microscopy, X-ray diffraction, and glancing angle X-ray diffraction) to characterize the yttrium implantation effect on extra low carbon steel.

E. Caudron; H. Buscail; Y. P. Jacob; M. F. Stroosnijder

1999-01-01

8

Coating liposomes with yttrium basic carbonate: Making hybrid nanocapsules  

Microsoft Academic Search

Novel yttrium basic carbonate hybrid nanocapsules have been prepared using liposome templates. The method resorts to urea hydrolysis to increase the precipitation driving force of Y(OH)CO3?xH2O homogeneously. The head groups at the outer vesicle layer act as adsorption sites for hydrolyzing Y(III) ions, thus assisting heterogeneous nucleation. The criteria behind the synthesis, as well as the potentialities of the advanced

Martn G. Bellino; Alberto E. Regazzoni

2009-01-01

9

Thermal Decomposition of Lanthanide, Yttrium, and Scandium Oxalates and Carbonates  

NASA Astrophysics Data System (ADS)

Data concerning the thermal decomposition of lanthanide, yttrium, and scandium oxalates and carbonates are surveyed. The complexity of the process, the large number of stages involved, and the dependence of the composition of the intermediates in the thermal transformations on the experimental conditions is noted. Certain process characteristics have been discovered and it is concluded that the decomposition process depends on the ionic radius of the metal. The bibliography includes 83 references.

Sharov, Vyacheslav A.; Bezdenezhnykh, G. V.

1981-07-01

10

Coating liposomes with yttrium basic carbonate: making hybrid nanocapsules.  

PubMed

Novel yttrium basic carbonate hybrid nanocapsules have been prepared using liposome templates. The method resorts to urea hydrolysis to increase the precipitation driving force of Y(OH)CO(3)xH(2)O homogeneously. The head groups at the outer vesicle layer act as adsorption sites for hydrolyzing Y(III) ions, thus assisting heterogeneous nucleation. The criteria behind the synthesis, as well as the potentialities of the advanced procedure, are stressed. PMID:19251267

Bellino, Martn G; Regazzoni, Alberto E

2009-02-21

11

Structural studies of the deuterides of carbon containing yttrium alloys  

Microsoft Academic Search

The present work describes a structural characterization of the yttriumcarbon compounds, Y2C and YCoC, and their corresponding deuterides using temperature desorption spectroscopy (TDS) and high-resolution powder X-ray and neutron diffraction. Carbon atoms orderly occupy 1\\/3 (YCoC) or 1\\/2 (Y2C) of the available octahedra, Y4Co2 and Y6, respectively. Strong YC interactions lead to the shrinking of these C-filled sites, with the

J. P. Maehlen; V. A. Yartys; B. C. Hauback

2003-01-01

12

Preparation of mesoporous carbon by steam activation of commercial activated carbon in the presence of yttrium oxide  

Microsoft Academic Search

Mesoporous carbon was prepared by steam activation of commercial activated carbon in the presence of yttrium oxide. The loading of yttrium nitrate (precursor of yttrium oxide) was 0.2, 0.6, 1.0 and 2.0 wt%. The weight lost and gases formed during heating were detected by using thermogravimetric analysis and mass spectroscopy. The surface area and the total volume of the mesoporous

W. Z. Shen; J. T. Zheng; Y. L. Zhang; J. G. Wang; Z. F. Qin

2003-01-01

13

Surface modifications induced by yttrium implantation on low manganesecarbon steel  

Microsoft Academic Search

Low manganesecarbon steel samples were ion implanted with yttrium. Sample compositions and structures were investigated before and after yttrium implantations to determine the yttrium distribution in the sample. Yttrium implantation effects were characterized using several analytical and structural techniques such as X-ray photoelectron spectroscopy, reflection high energy electron diffraction, X-ray diffraction, glancing angle X-ray diffraction and Rutherford backscattering spectrometry. In

E Caudron; H Buscail; V. A. C Haanapel; Y. P Jacob; M. F Stroosnijder

1999-01-01

14

Selective encapsulation of the carbides of yttrium and titanium into carbon nanoclusters  

Microsoft Academic Search

Characterization of the arc-discharge deposits at the cathode from anodes containing yttrium oxide and titanium by transmission electron microscopy and x-ray diffraction shows different results with respect to an encapsulation of the metal carbides into carbon clusters. Yttrium carbide is encapsulated into carbon nanoclusters in a crystalline phase. The formation of titanium carbide, on the other hand, preempts the formation

Supapan Seraphin; Dan Zhou; Jun Jiao; James C. Withers; Raouf Loutfy

1993-01-01

15

Optically transparent ceramics based on yttrium oxide using carbonate and alkoxy precursors  

Microsoft Academic Search

Methods for producing optically transparent ceramic materials based on Y2O3 using carbonate and alkoxy precursors are considered. It is established that ceramic synthesized from yttrium isopropylate\\u000a has better optical parameters than ceramics based on yttrium carbonate under equal heat treatment and firing regimes.

A. V. Belyakov; D. O. Lemeshev; E. S. Lukin; G. P. Valnin; E. E. Grinberg

2006-01-01

16

Hot corrosion resistances of yttrium-implanted and unimplanted low-manganesecarbon steels  

Microsoft Academic Search

Yttrium-implanted and unimplanted low-manganesecarbon steel samples were analyzed at T=700C and under an oxygen partial pressure PO2=0.04 Pa for 24 h to observe the yttrium implantation effect on sample hot corrosion resistance. The yttrium implantation effect on low-manganesecarbon steel was investigated using several analytical and structural techniques such as Rutherford backscattering spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), reflection high energy

E Caudron; H Buscail

2000-01-01

17

Selective encapsulation of the carbides of yttrium and titanium into carbon nanoclusters  

SciTech Connect

Characterization of the arc-discharge deposits at the cathode from anodes containing yttrium oxide and titanium by transmission electron microscopy and x-ray diffraction shows different results with respect to an encapsulation of the metal carbides into carbon clusters. Yttrium carbide is encapsulated into carbon nanoclusters in a crystalline phase. The formation of titanium carbide, on the other hand, preempts the formation of the carbon---carbon bonds necessary to form the carbon cages, so that only titanium carbide clusters are observed. Thermodynamic data support the interpretation of the results.

Seraphin, S.; Zhou, D. (Department of Materials Science and Engineering, University of Arizona, Tucson, Arizona 85721 (United States)); Jiao, J. (Department of Physics, University of Airzona, Tucson, Arizona 85721 (United States)); Withers, J.C.; Loutfy, R. (Materials and Electrochemical Research Corporation, Tucson, Arizona 85706 (United States))

1993-10-11

18

Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate with methanol over binary zinc-yttrium oxides  

Microsoft Academic Search

The binary zincyttrium oxides were prepared by co-precipitation method, characterized and tested in the synthesis of DMC via transesterification of ethylene carbonate with methanol. The catalytic results showed that the catalyst with Zn\\/Y molar ratio of 3 and calcined at 400C exhibited superior catalytic activity, corresponding to TOF of 236mmol\\/gcath. Appropriate content of yttrium in the catalyst enhanced the catalytic

Liguo Wang; Ying Wang; Shimin Liu; Liujin Lu; Xiangyuan Ma; Youquan Deng

2011-01-01

19

Fabrication of yttrium aluminum garnet transparent ceramics from yttria nanopowders synthesized by carbonate precipitation  

Microsoft Academic Search

Nanocrystalline yttria powders have been successfully synthesized by using yttrium nitrate as starting salt and ammonium hydrogen\\u000a carbonate as precipitant. It was found that a small amount of ammonia sulfate in the yttrium nitrate solution can effectively\\u000a reduce the agglomeration and the resultant powders display good dispersion. Pure cubic phase yttria powders were prepared\\u000a by calcining the precipitate at 1100C

Hua Gong; Dingyuan Tang; Hui Huang; Jan Ma

2009-01-01

20

Light emission of double-walled carbon nanotube filaments doped with yttrium and europium  

Microsoft Academic Search

As the potential applications of carbon nanotubes in the field of electroluminescence, elements yttrium and europium were\\u000a introduced to modify the emission properties of double-walled carbon nanotubes (DWNTs) to obtain higher efficacy and other\\u000a properties. The light emission spectrum of the Y-Eu-doped DWNT filament is suppressed in the near-infrared range, while enhanced\\u000a in the mid-infrared range. The doped DWNT filament

QinKe Shu; KunLin Wang; JinQuan Wei; HongWei Zhu; XinMing Li; Xi Chen; Yi Jia; XuChun Gui; ErYang Xu; DeHai Wu

2009-01-01

21

Dye adsorption on mesoporous activated carbon fiber obtained from pitch containing yttrium complex  

Microsoft Academic Search

The adsorption of acid dyes (Acid Blue 9, Acid Blue 74, Acid Orange 10, and Acid Orange 51), direct dyes (Direct Black 19, Direct Yellow 11, and Direct Yellow 50), and basic dyes (Basic Brown 1 and Basic Violet 3) on a highly mesoporous activated carbon fiber (Y-ACF) obtained from pitch containing yttrium acetylacetonate was investigated in terms of size

Hisashi Tamai; Takeshi Yoshida; Masahiko Sasaki

1999-01-01

22

Removal of arsenite and arsenate ions from aqueous solution by basic yttrium carbonate  

Microsoft Academic Search

A new method has been developed to remove arsenite and arsenate ions from aquatic systems by using basic yttrium carbonate (BYC). Various parameters such as pH, anion concentration and reaction time were studied to establish optimum conditions. The removal by adsorption of arsenite and arsenate ions was found to be > 99% depending on initial concentration in the pH range

Syed A. Wasay; Akira Uchiumi; Shuzo Tokunaga

1996-01-01

23

Preparation of yttrium, lanthanum, cerium, and neodymium basic carbonate particles by homogeneous precipitation  

SciTech Connect

Uniform yttrium, lanthanum, cerium, and neodymium basic carbonate particles were prepared by homogeneous precipitation. Powders were characterized with respect to size, shape, crystal structure, and thermal decomposition behavior. Yttria precursor particles were spherical, monosized (0.4 {mu}m), and amorphous; whereas lanthana, neodymia, and ceria precursors were prismatic (ranging from 1 to 6 {mu}m in size) and crystalline. Crystal structure was found to be ancylite-type orthorhombic symmetry in all three cases. Upon heating in air, yttrium, lanthanum, and neodymium precursors underwent two-step decomposition to first form oxycarbonate and then oxide. Cerium hydroxycarbonate decomposed in a single step to form the oxide.

Akinc, M.; Sordelet, D. (Iowa State Univ., Ames (USA))

1987-07-01

24

Preparation and phase composition optimization of yttrium silicates\\/SiC multilayer coating coated carbon\\/carbon composites  

Microsoft Academic Search

In order to optimize the phase composition and improve the oxidation resistance of yttrium silicates coating, Y2SiO5-Y2Si2O7-Y4Si3O12 coatings with different phase composition were deposited on the surface of SiC pre-coated carbon\\/carbon (C\\/C) composites using a hydrothermal electrophoretic deposition process. The as-prepared multilayer coatings were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The influence of phase composition on

Wang Ya-qin; Huang Jian-feng; Chen Zheng-hui; Cao Li-yun

2012-01-01

25

Carbonate complexation of yttrium and the rare earth elements in natural waters 1 1 Associate Editor: D. Rimstidt  

Microsoft Academic Search

Potentiometric measurements of Yttrium and Rare Earth Element (YREE) complexation by carbonate and bicarbonate indicate that the quality of carbonate complexation constants previously obtained via solvent exchange analyses are superior to characterizations obtained using solubility and adsorptive exchange analyses. The results of our analyses at 25C are combined with the results of previous solvent exchange analyses to obtain YREE carbonate

Yu-Ran Luo; Robert H. Byrne

2004-01-01

26

Generation, Properties, and Order Packing of Monodispersed Spherical Colloid Particles of Yttrium Hydroxy-Carbonate: A Colloidal Route to Minimizing Voids in Ceramics.  

National Technical Information Service (NTIS)

Yttrium hydroxy-carbonate particles were prepared by decomposition of urea in yttrium nitrate solutions. The nucleation and growth were studied in silica-seeded and unseeded systems. Precipitation took place only under neutral conditions. In unseeded syst...

P. Mwesigwa-Kayima

1987-01-01

27

In Situ High-Temperature X-Ray Diffraction Characterization of Yttrium-Implanted Extra Low-Carbon Steel  

Microsoft Academic Search

Yttrium-implanted and unimplanted extra low-carbon steel samples were analyzed at T = 700C and under an oxygen partial pressure PO2 = 0.04Pa for 24 h to show the yttrium implantation effect on extra low-carbon steel high-temperature corrosion resistance. Sample oxidation weight gains were studied by thermogravimetry, and structural analyses were performed using in situ high-temperature X-ray diffraction with the same

E. Caudron; H. Buscail; S. Perrier

1999-01-01

28

Preparation of yttrium, lanthanum, cerium, and neodymium basic carbonate particles by homogeneous precipitation  

Microsoft Academic Search

Uniform yttrium, lanthanum, cerium, and neodymium basic carbonate particles were prepared by homogeneous precipitation. Powders were characterized with respect to size, shape, crystal structure, and thermal decomposition behavior. Yttria precursor particles were spherical, monosized (0.4 μm), and amorphous; whereas lanthana, neodymia, and ceria precursors were prismatic (ranging from 1 to 6 μm in size) and crystalline. Crystal structure was found

M. Akinc; D. Sordelet

1987-01-01

29

Synthesis of polyethercarbonate from carbon dioxide and cyclohexene oxide by yttriummetal coordination catalyst  

Microsoft Academic Search

The copolymerization of carbon dioxide and cyclohexene oxide to generate polyethercarbonate using yttriummetal coordination catalyst was carried out in this study. After testing several catalyst systems, it was found that the system consisting of Y(CF3CO2)3(I), Zn(Et)2(II),and glycerine(III) in the solvent of 1,3-dioxolane was the most effective catalyst. The IR and 1H NMR spectra indicated that the resulting copolymer was indeed

Tsung-Ju Hsu; Chung-Sung Tan

2001-01-01

30

Optical characterization of spherical fine particles of glassy Eu 3+ doped yttrium basic carbonates  

Microsoft Academic Search

Spherical fine particles of glassy Eu3+ doped yttrium basic carbonate, whose sizes are about 300 nm in diameter, are prepared by a co-precipitation method using urea as a precipitation generator. The optical properties concerned with the ff transitions of Eu3+ are investigated for the as-prepared powder and the powder samples calcined at 300 and 550 C. As the calcination temperature

Masanori Tanaka; Yoshihiro Nishisu; Mikio Kobayashi; Atusi Kurita; Hiromasa Hanzawa; Yasuo Kanematsu

2003-01-01

31

Transformation of carbon monoxide dimer surface structures on yttrium oxide modified by silver  

Microsoft Academic Search

1.It has been established that introducing Ions of silver(II) in yttrium (III) oxide leads to the formation of a significant concentration of a paramagnetic dimer species (CO)2- in the course of the adsorption of carbon monoxide, and that these dimers exhibit high thermal stability and reactivity.2.Kinetic dependences have been obtained for the transformation of the paramagnetic species O2-, CO2-, (CO)2-,

S. N. Vydrin; A. V. Bobolev; A. Yu. Loginov

1987-01-01

32

Carbon doped yttrium aluminum garnet (YAG:C)A new phosphor for radiation dosimetry  

Microsoft Academic Search

Carbon doped yttrium aluminum garnet (YAG:C) samples were prepared by a simple process involving melting of polycrystalline YAG powder in graphite environment using electron gun of a vacuum deposition system meant for deposition of thin films. The samples showed excellent TL and OSL response in the dose range of 10mGy to 100Gy. However, the YAG treated in a similar manner

M. S. Kulkarni; K. P. Muthe; N. S. Rawat; D. R. Mishra; M. B. Kakade; S. Ramanathan; S. K. Gupta; B. C. Bhatt; J. V. Yakhmi; D. N. Sharma

2008-01-01

33

Comparison of the erbium-yttrium aluminum garnet and carbon dioxide lasers for in vitro bone and cartilage ablation  

SciTech Connect

The in vitro bone- and cartilage-ablation characteristics of the solid-state erbium:yttrium aluminum garnet laser were compared to those of the carbon dioxide laser. Ablations of fresh, frozen cadaver septal cartilage and maxillary sinus bone were performed using total energies between 1 and 6 J. Specimens were studied using hematoxylin and eosin stain and digitized, computer-assisted measurements of 35-mm photographs. Erbium-yttrium aluminum garnet-ablated bone averaged 5 microns of adjacent tissue thermal injury, compared with 67 microns with carbon dioxide-ablated bone. Erbium-yttrium aluminum garnet-ablated cartilage averaged 2 microns of adjacent tissue thermal injury, compared with 21 microns with the carbon dioxide-ablated cartilage. The tissue-ablation characteristics of the erbium-yttrium aluminum garnet laser are promising for future otolaryngologic applications.

Gonzalez, C.; van de Merwe, W.P.; Smith, M.; Reinisch, L. (Uniformed Services Univ. of the Health Sciences, Bethesda, MD (USA))

1990-01-01

34

Carbonates.  

National Technical Information Service (NTIS)

There are approximately 150 carbonate minerals that occur in nature; however, most of these carbonates are relatively rare. The most common rock-forming carbonates are calcite (CaC03) and dolomite (CaMg(C03)2), which account for over 90 % of natural carbo...

D. W. Ming

2001-01-01

35

Comparison of the erbium-yttrium aluminum garnet and carbon dioxide lasers for in vitro bone and cartilage ablation  

Microsoft Academic Search

The in vitro bone- and cartilage-ablation characteristics of the solid-state erbium:yttrium aluminum garnet laser were compared to those of the carbon dioxide laser. Ablations of fresh, frozen cadaver septal cartilage and maxillary sinus bone were performed using total energies between 1 and 6 J. Specimens were studied using hematoxylin and eosin stain and digitized, computer-assisted measurements of 35-mm photographs. Erbium-yttrium

Carlos Gonzalez; Willem P. Van De Merwe; Michael Smith; Lou Reinisch

1990-01-01

36

PET Imaging of Soluble Yttrium-86-Labeled Carbon Nanotubes in Mice  

PubMed Central

Background The potential medical applications of nanomaterials are shaping the landscape of the nanobiotechnology field and driving it forward. A key factor in determining the suitability of these nanomaterials must be how they interface with biological systems. Single walled carbon nanotubes (CNT) are being investigated as platforms for the delivery of biological, radiological, and chemical payloads to target tissues. CNT are mechanically robust graphene cylinders comprised of sp2-bonded carbon atoms and possessing highly regular structures with defined periodicity. CNT exhibit unique mechanochemical properties that can be exploited for the development of novel drug delivery platforms. In order to evaluate the potential usefulness of this CNT scaffold, we undertook an imaging study to determine the tissue biodistribution and pharmacokinetics of prototypical DOTA-functionalized CNT labeled with yttrium-86 and indium-111 (86Y-CNT and 111In-CNT, respectively) in a mouse model. Methodology and Principal Findings The 86Y-CNT construct was synthesized from amine-functionalized, water-soluble CNT by covalently attaching multiple copies of DOTA chelates and then radiolabeling with the positron-emitting metal-ion, yttrium-86. A gamma-emitting 111In-CNT construct was similarly prepared and purified. The constructs were characterized spectroscopically, microscopically, and chromatographically. The whole-body distribution and clearance of yttrium-86 was characterized at 3 and 24 hours post-injection using positron emission tomography (PET). The yttrium-86 cleared the blood within 3 hours and distributed predominantly to the kidneys, liver, spleen and bone. Although the activity that accumulated in the kidney cleared with time, the whole-body clearance was slow. Differential uptake in these target tissues was observed following intraveneous or intraperitoneal injection. Conclusions The whole-body PET images indicated that the major sites of accumulation of activity resulting from the administration of 86Y-CNT were the kidney, liver, spleen, and to a much less extent the bone. Blood clearance was rapid and could be beneficial in the use of short-lived radionuclides in diagnostic applications.

Jaggi, Jaspreet S.; Finn, Ronald D.; Zanzonico, Pat B.; Villa, Carlos; Rey, Diego; Mendenhall, Juana; Batt, Carl A.; Njardarson, Jon T.; Scheinberg, David A.

2007-01-01

37

Synthesis and Structure of Hydrated Yttrium Carbonate, Y2(Co3)332.79H2O  

Microsoft Academic Search

Crystalline yttrium carbonate, Y2(CO3)32.79H2O, was synthesized using ammonium bicarbonate as precipitant. The X ray diffraction data were indexed in the triclinic system with cell parameters a = 19. 076, b = 22. 312, c = 7. 823, ? = 94. 493, ? = 91. 397 and ? = 112. 663. The structure is closely related to those of tengerite type

Song Liu; Rongjun Ma; Rongying Jiang; Fangcheng Luo

2000-01-01

38

Synergistic effects of sequential carbon dioxide and neodymium:yttrium aluminum garnet laser injuries. Experimental observations and measurements  

Microsoft Academic Search

The carbon dioxide and neodymium:yttrium aluminum garnet lasers have well documented but characteristically different biological effects, yet little is known about their cumulative, synergistic, or paradoxical effects when used sequentially on living tissue. Using a Merrimack ML 880 laser, a series of superimposed CO and Nd:YAG lesions in various combinations were produced on the undersurface of dog tongues. Therapeutic time

W. J. Primrose; G. A. McDonald; M. J. OBrien; C. W. Vaughan; M. S. Strong

1987-01-01

39

The effect of chromium, carbon, and yttrium on the oxidation of nickel-base alloys in high temperature water  

Microsoft Academic Search

Since the surface film has been implicated in several models of intergranular stress corrosion cracking (IGSCC) of nickel-base alloys, this study was initiated to provide a foundation for the future study of a possible link between the nature of the surface film and IG crack susceptibility. The influence of chromium, carbon, and yttrium on the nature of the surface film

T. M. Angeliu

1993-01-01

40

Yttrium-Iron-Garnet as a molten carbonate fuel cell cathode  

SciTech Connect

Yttrium iron garnets (YIG), Y{sub 3}FO{sub 5}0{sub 12} barium ferrite, BaFe{sub l2}O{sub l9}, were synthesized and characterized as alternate molten carbonate fuel cell cathode materials. Doping and calcining conditions were established to synthesize phase pure doped YIG. The conductivity of singly doped YIG was found to be lower than that of lithiated NiO. The performance of singly doped YIG cathode in an in-cell test at the Institute of Gas Technology was below the current NiO cathode due to high polarization loss. Doubly doped compositions were synthesized and characterized. A second dopant was identified and optimized to achieve a conductivity value comparable to lithiated NiO. The advanced composition also exhibited improved corrosion characteristics at 10 atm pressure under cathode gas conditions. A barium ferrite based magnetoplumbite material was tested as a potential cathode candidate in molten carbonate. The material formed a reaction product that was conductive at room temperature; it also exhibited some magnetization. The reaction product was characterized to have Fe{sub 2}O{sub 3} structure. Attempts to synthesize single phase Ba-doped Fe{sub 2}O{sub 3} was unsuccessful. The doped YIG material appears to provide the solutions to two problems that currently limit the MCFC performance and life, namely, cathode stability in the melt and high conductivity in the oxidant atmosphere.

Khandkar, A. (Ceramatec, Inc., Salt Lake City, UT (United States))

1992-09-01

41

Preparation of yttrium hexacyanoferrate\\/carbon nanotube\\/Nafion nanocomposite film-modified electrode: Application to the electrocatalytic oxidation of l-cysteine  

Microsoft Academic Search

An yttrium hexacyanoferrate nanoparticle\\/multi-walled carbon nanotube\\/Nafion (YHCFNP\\/MWNT\\/Nafion)-modified glassy carbon electrode (GCE) was constructed. Several techniques, including infrared spectroscopy, energy dispersive spectrometry, scanning electron microscopy and electrochemistry, were performed to characterize the yttrium hexacyanoferrate nanoparticles. The electrochemical behavior of the YHCFNP\\/MWNT\\/Nafion-modified GCE in response to l-cysteine oxidation was studied. The response current of l-cysteine oxidation at the YHCFNP\\/MWNT\\/Nafion-modified GCE was obviously

Lingbo Qu; Suling Yang; Gang Li; Ran Yang; Jianjun Li; Lanlan Yu

2011-01-01

42

In-situ high temperature X-ray diffraction characterization of yttrium implanted extra low carbon steel and pure iron  

Microsoft Academic Search

Yttrium implanted and unimplanted extra low carbon steel and pure electrolytic iron samples were investigated at high temperature (T=700C) under oxygen partial pressure PO2=0.04Pa to observe their oxidation resistances under these experimental conditions. High temperature oxidation tests were carried out by thermogravimetry and by in-situ high temperature X-ray diffraction. The aim of this paper is to show the initial nucleation

E Caudron; H Buscail

2000-01-01

43

Correlation of optical properties and temperature-induced irreversible phase transitions in europium-doped yttrium carbonate nanoparticles  

Microsoft Academic Search

Nanophase europium-doped yttrium carbonate precursors are subjected to heat treatments, ranging from 300C to 1100C for dwell times of 5min, 30min, and 180min. XRD, TEM, FT-IR, fluorescence, fluorescence excitation, and fluorescence lifetime measurements are used to characterize the materials. Upon heating, the material transitions through several amorphous stages until it reaches the crystalline cubic Y2O3 phase. DSC measurements show an

Ray Gunawidjaja; Thandar Myint; Hergen Eilers

44

Carbonate complexation of yttrium and the rare earth elements in natural waters  

NASA Astrophysics Data System (ADS)

Potentiometric measurements of Yttrium and Rare Earth Element (YREE) complexation by carbonate and bicarbonate indicate that the quality of carbonate complexation constants previously obtained via solvent exchange analyses are superior to characterizations obtained using solubility and adsorptive exchange analyses. The results of our analyses at 25C are combined with the results of previous solvent exchange analyses to obtain YREE carbonate complexation constants over a wide range of ionic strength (0 ? I ?3 molal). YREE carbonate complexation constants are reported for the following equilibria, M 3++nHCO 3-?M(CO 3) n3-2n+nH +, where n = 1 or 2. Formation constants written in terms of HCO 3- concentrations require only minor corrections for ion pairing relative to the corrections required for constants expressed in terms of CO 32- concentrations. Formation constants for the above complexation equilibria, CO3H? 1=[MCO 3+][H +][M 3+] -1[HCO 3-] -1 and CO3H? 2=[M(CO 3) 2-][H +] 2[M 3+] -1[HCO 3-] -2, have very similar dependencies on ionic strength because the reaction MCO 3++HCO 3-?M(CO 3) 2-+H + is isocoulombic. Potentiometric analyses indicate that the dependence of log CO3H? 1 and log CO3H? 2 on ionic strength at 25C is given as logCO3H? n= logCO3H? n0-4.088 I0.5/(1+3.033 I0.5)+0.042 I where CO3H? n0 denotes a formation constant at 25C and zero ionic strength. Recommended values for log CO3H? 1 and log CO3H? 20, expressed in the form (element, -log CO3H? 10, -log CO3H? 20), are as follows: (Y, 2.85, 8.03), (La, 3.60, 9.36), (Ce, 3.27, 8.90), (Pr, 3.10, 8.58), (Nd, 3.05, 8.49), (Sm, 2.87, 8.13), (Eu, 2.85, 8.03), (Gd, 2.94, 8.18), (Tb, 2.87, 7.88), (Dy, 2.77, 7.75), (Ho, 2.78, 7.66), (Er, 2.72, 7.54), (Tm, 2.65, 7.39), (Yb, 2.53, 7.36), (Lu, 2.58, 7.29).

Luo, Yu-Ran; Byrne, Robert H.

2004-02-01

45

Enrichment of yttrium from rare earth concentrate by ammonium carbonate leaching and peroxide precipitation  

Microsoft Academic Search

The rare earth elements (REE) solubility with ammonium carbonate vary progressively from element to element, the heavy rare earth elements (HRE) being more soluble than the light rare earth elements (LRE). Their solubility is function of the carbonate concentration and the kind of carbonate as sodium, potassium and ammonium. In this work, it is explored this ability of the carbonate

Mari E. de Vasconcellos; S. M. R. da Rocha; W. R. Pedreira; Carlos A. da S. Queiroz; Alcdio Abro

2006-01-01

46

Generation, properties, and order packing of monodispersed spherical colloid particles of yttrium hydroxy-carbonate: A colloidal route to minimizing voids in ceramics  

Microsoft Academic Search

Yttrium hydroxy-carbonate particles were prepared by decomposition of urea in yttrium nitrate solutions. The nucleation and growth were studied in silica-seeded and unseeded systems. Precipitation took place only under neutral conditions. In unseeded systems, homogeneous nucleation yielded 3 x 10¹° nucleicm³ while in seeded precipitation enough nuclei were produced to bring the total number of particles to 4 x 10¹°cm³.

Mwesigwa-Kayima

1987-01-01

47

In-situ X-ray diffraction study of the behaviour of yttrium implanted low manganese-carbon steel at high temperature  

Microsoft Academic Search

Yttrium implanted and unimplanted low manganese-carbon steel samples were analysed at T=700C and under oxygen partial pressure (Po2=0.04 Pa) for 24 h to show the yttrium implantation effect on sample oxidation resistance at high temperature. Weight gains resulting from sample oxidation were studied by thermogravimetry and structural analyses were performed by in-situ high temperature X-ray diffraction under the same experimental

E Caudron; H Buscail; R Cueff

2000-01-01

48

Growth and performance of yttrium oxide as an ideal high-kappa gate dielectric for carbon-based electronics.  

PubMed

High-quality yttrium oxide (Y(2)O(3)) is investigated as an ideal high-kappa gate dielectric for carbon-based electronics through a simple and cheap process. Utilizing the excellent wetting behavior of yttrium on sp(2) carbon framework, ultrathin (about few nm) and uniform Y(2)O(3) layers have been directly grown on the surfaces of carbon nanotube (CNT) and graphene without using noncovalent functionalization layers or introducing large structural distortion and damage. A top-gate CNT field-effect transistor (FET) adopting 5 nm Y(2)O(3) layer as its top-gate dielectric shows excellent device characteristics, including an ideal subthreshold swing of 60 mV/decade (up to the theoretical limit of an ideal FET at room temperature). The high electrical quality Y(2)O(3) dielectric layer has also been integrated into a graphene FET as its top-gate dielectric with a capacitance of up to 1200 nF/cm(2), showing an improvement on the gate efficiency and on state transconductance of over 100 times when compared with that of its back-gate counterpart. PMID:20455575

Wang, Zhenxing; Xu, Huilong; Zhang, Zhiyong; Wang, Sheng; Ding, Li; Zeng, Qingsheng; Yang, Leijing; Pei, Tian; Liang, Xuelei; Gao, Min; Peng, Lian-Mao

2010-06-01

49

Comparative carbonate complexation of yttrium and gadolinium at 25 C and 0.7 mol dm ?3 ionic strength  

Microsoft Academic Search

Stability constants for yttrium and gadolinium complexation by carbonate ions have been measured by solvent extraction procedures at 25 C and 0.7 mol dm?3 ionic strength. The results of six experiments indicate that logCO3?1?(Y) = 5.71, logCO3?2?(Y) = 10.34, logCO3?1?(Gd) = 5.65 and logCO3?2?(Gd) = 10.12 whereCO3?n?(M) = [M(CO3)n3 ? 2n][M3+]?1[CO32?]T?n, [ ] represents concentrations and [CO32?]T = [CO32?] +

Xuewu Liu; Robert H. Byrne

1995-01-01

50

Effect of yttrium and chromium ion implantation on crevice electrochemical behavior of carbon steel in sodium chloride solution  

NASA Astrophysics Data System (ADS)

In order to study the effect of yttrium (Y) and chromium (Cr) ion implantation on the crevice corrosion behavior of carbon steel, the carbon steel was implanted with Y and Cr ion using MEVVA source at an energy of 40 keV. Electrochemical measurement was employed to evaluate the crevice corrosion of implanted carbon steel in NaCl solution. The results indicated that, after Y and Cr ion implantation, the carbon steel's crevice corrosion resistance and electrochemical characteristic were significantly improved in NaCl solution when the implantation dose of Y increased. Auger electron spectroscopy (AES) analysis of the implanted carbon steel manifested that the surface layer was mainly composed of elements Fe, Cr, O, and Y. Most of element Y was located near the outside region of the surface layer/solution interface, whereas Cr was enriched in the transition area between surface layer and matrix. By X-ray photoelectron spectroscopy (XPS) analysis, the implanted Y was in the form of Y 2O 3, whereas Cr in the form of Cr 2O 3 in the surface layer. The mechanism of the crevice corrosion resistance and electrochemical characteristic improvement was that, after Y and Cr ion implantation, the surface layer seemed to be constituted by Y 2O 3 and Cr 2O 3. The surface layer acted as a barrier to reduce the metal matrix to contact with the corrosion medium such as inhibiting Cl - ions from corroding the layer.

Liang, Chenghao; Huang, Naibao

2008-12-01

51

Oxidation resistant yttrium silicates coating for carbon\\/carbon composites prepared by a novel in-situ formation method  

Microsoft Academic Search

Yttrium silicates interlayer coatings of the SiC\\/yttrium silicates\\/borosilicate glass multi-layer coating system were prepared by a novel in-situ formation method using Si and Y2O3 as starting materials in an oxidation atmosphere. The surface and cross-section microstructures of the coatings were characterized by XRD and SEM analyses. Oxidation resistance of the coated samples was tested. Results showed that dense yttrium silicate

Jian-Feng Huang; He-Jun Li; Xie-Rong Zeng; Fei Deng; Xin-bo Xiong; Ke-Zhi Li

2007-01-01

52

Evaluation of carbon deposition behavior on the nickel\\/yttrium-stabilized zirconia anode-supported fuel cell fueled with simulated syngas  

Microsoft Academic Search

The nickel\\/yttrium-stabilized zirconia (Ni\\/YSZ) anode-supported solid oxide fuel cells (SOFCs) have been operated under various simulated syngases at different temperatures to investigate the degradation behavior of the cells caused by carbon deposition. The results show that the carbon morphology and the cell performance degradation are influenced significantly by the operation temperature. The stability of the cell fueled with syngas can

Tao Chen; Wei Guo Wang; He Miao; Tingshuai Li; Cheng Xu

2011-01-01

53

Correlation of optical properties and temperature-induced irreversible phase transitions in europium-doped yttrium carbonate nanoparticles  

SciTech Connect

Nanophase europium-doped yttrium carbonate precursors are subjected to heat treatments, ranging from 300 Degree-Sign C to 1100 Degree-Sign C for dwell times of 5 min, 30 min, and 180 min. XRD, TEM, FT-IR, fluorescence, fluorescence excitation, and fluorescence lifetime measurements are used to characterize the materials. Upon heating, the material transitions through several amorphous stages until it reaches the crystalline cubic Y{sub 2}O{sub 3} phase. DSC measurements show an exothermic transition at 665.7 Degree-Sign C, indicating the formation of crystalline Y{sub 2}O{sub 3}. The grain size development is fitted by the relaxation equation and yields an activation energy of 50.3 kJ/mol. The amorphous phases are characterized by inhomogenously broadened optical spectra. Heating up to 700 Degree-Sign C leads to an increased fluorescence lifetime (from about 1 ms to 2.4 ms). As the material is heated to higher temperatures and completes the formation of the crystalline cubic Y{sub 2}O{sub 3} phase, the optical spectra become narrower and the fluorescence lifetime decreases to about 1.2 ms. - Graphical abstract: Fluorescence lifetimes of Eu-doped Y{sub 2}O{sub 3} precursors heated for 5, 30, and 180 min to various temperatures. Highlights: Black-Right-Pointing-Pointer Irreversible phase transitions in nanoparticles are of interest for thermometry. Black-Right-Pointing-Pointer Eu-doped nanophase yttrium carbonate precursors were heat-treated. Black-Right-Pointing-Pointer The material undergoes decomposition and crystallization. Black-Right-Pointing-Pointer Morphological and optical properties are measured. Black-Right-Pointing-Pointer Optical properties can be used to deduce the temperature.

Gunawidjaja, Ray; Myint, Thandar [Applied Sciences Laboratory, Institute for Shock Physics, Washington State University, Spokane, WA 99210-1495 (United States); Eilers, Hergen, E-mail: eilers@wsu.edu [Applied Sciences Laboratory, Institute for Shock Physics, Washington State University, Spokane, WA 99210-1495 (United States)

2011-12-15

54

The inhibition of neuronal calcium ion channels by trace levels of yttrium released from carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes (CNTs) are used with increasing frequency in neuroengineering applications. CNT scaffolds are used to transmit electrical stimulation to cultured neurons and to control outgrowth and branching patterns of neurites. CNTs have been reported to disrupt normal neuronal function including alterations in endocytotic capability and inhibition of ion channels. Calcium ion channels regulate numerous neuronal and cellular functions including

Lorin M. Jakubek; Spiro Marangoudakis; Jesica Raingo; Xinyuan Liu; Diane Lipscombe; Robert H. Hurt

2009-01-01

55

PET Imaging of Soluble Yttrium86-Labeled Carbon Nanotubes in Mice  

Microsoft Academic Search

BackgroundThe potential medical applications of nanomaterials are shaping the landscape of the nanobiotechnology field and driving it forward. A key factor in determining the suitability of these nanomaterials must be how they interface with biological systems. Single walled carbon nanotubes (CNT) are being investigated as platforms for the delivery of biological, radiological, and chemical payloads to target tissues. CNT are

Michael R. McDevitt; Debjit Chattopadhyay; Jaspreet S. Jaggi; Ronald D. Finn; Pat B. Zanzonico; Carlos Villa; Diego Rey; Juana Mendenhall; Carl A. Batt; Jon T. Njardarson; David A. Scheinberg; Andrew Boswell

2007-01-01

56

Mechanochemical formation of novel catalyst for preparing carbon nanotubes: nanocrystalline yttrium aluminum iron perovskite  

Microsoft Academic Search

The first mechanochemical synthesis of nanosized YAl1?xFexO3 (x=0 to 1) perovskite powders is reported. Continuous ball-milling of the yttria, aluminum hydroxide and iron oxide powders over 24 h led to the formation of nanocrystals with a size of nearly 20 nm. It has been found that the material exhibits a catalytic property for preparing carbon nanotubes.

Xiaomei Guo; Jifa Qi; Kenji Sakurai

2003-01-01

57

Hydrogenation of carbon dioxide and aryl isocyanates by a tetranuclear tetrahydrido yttrium complex. Isolation, structures, and CO2 insertion reactions of methylene diolate and mu3-oxo yttrium complexes.  

PubMed

The reaction of carbon dioxide with a tetranuclear tetrahydrido yttrium complex [(C5Me4SiMe3)Y(mu-H)]4(L) (L = Me3SiCC(H)C(H)CSiMe3) (1) rapidly afforded the corresponding bis(methylene diolate) complex [(C5Me4SiMe3)Y]4(mu-O2CH2)2(L) (2), while the reactions of an aryl isocyanate with 1 led to selective formation of the mu3-oxo complex [(C5Me4SiMe3)Y]4(mu-O)( mu-H)2(L) (5) or [(C5Me4SiMe3)Y]4(mu-O)2(L) (7), depending on the substrate ratio. Both the methylene diolate and the oxo complexes can undergo CO2 insertion reactions to give the corresponding carbonate complexes. These reactions not only yield a new series of polynuclear yttrium complexes having novel structures but also shed new light on the mechanistic aspects of the heterogeneous hydrogenation of COmicron2. The high reactivity of the polynuclear mu3-oxo yttrium complexes 5 and 7 could also make them novel molecular models for study of metal oxide-supported catalysts. PMID:15225025

Tardif, Olivier; Hashizume, Daisuke; Hou, Zhaomin

2004-07-01

58

Correlation of optical properties and temperature-induced irreversible phase transitions in europium-doped yttrium carbonate nanoparticles  

NASA Astrophysics Data System (ADS)

Nanophase europium-doped yttrium carbonate precursors are subjected to heat treatments, ranging from 300 C to 1100 C for dwell times of 5 min, 30 min, and 180 min. XRD, TEM, FT-IR, fluorescence, fluorescence excitation, and fluorescence lifetime measurements are used to characterize the materials. Upon heating, the material transitions through several amorphous stages until it reaches the crystalline cubic Y2O3 phase. DSC measurements show an exothermic transition at 665.7 C, indicating the formation of crystalline Y2O3. The grain size development is fitted by the relaxation equation and yields an activation energy of 50.3 kJ/mol. The amorphous phases are characterized by inhomogenously broadened optical spectra. Heating up to 700 C leads to an increased fluorescence lifetime (from about 1 ms to 2.4 ms). As the material is heated to higher temperatures and completes the formation of the crystalline cubic Y2O3 phase, the optical spectra become narrower and the fluorescence lifetime decreases to about 1.2 ms.

Gunawidjaja, Ray; Myint, Thandar; Eilers, Hergen

2011-12-01

59

Studies on the reaction of ammonium fluoride with lithium carbonate and yttrium oxide  

Microsoft Academic Search

The reaction of Y2O3 and Li2CO3 with NH4F to produce LiYF4 was studied by thermogravimetric and X-ray diffraction methods. NH4F reacts easily with Li2CO3 in a one-step exothermic process. Fluorination of yttrium oxide gives first YF31.5NH3 which which decomposes at 300380C to YF3 + NH3. This process is exothermic. In the absence of excess NH4F, an amount of YOF is

Ewa Kowalczyk; Ryszard Diduszko; Zbigniew Kowalcyzyk; Tomasz Leszczy?ski

1995-01-01

60

Yttrium polyoxometalates. Synthesis and characterization of a carbonate-encapsulated sandwich-type complex.  

PubMed

Reaction of A-alpha-PW(9)O(34)(9)(-) with YCl(3) in an aqueous Na(2)CO(3) solution produces a dianion-encapsulated A-type sandwich polyoxometalate, (YOH(2))(3)(CO(3))(A-alpha-PW(9)O(34))(2)(11)(-). The X-ray structure of this complex reveals that three Y(III) ions are sandwiched between two A-alpha-PW(9)O(34)(9)(-) moieties and that a carbonate dianion is encapsulated in the same plane as the three Y(III) atoms. The oxygen atoms of the CO(3)(2)(-) are sitting at the midpoints of the sides of the triangle formed by the three Y(III) ions. (31)P and (13)C NMR studies confirm that this complex is significantly more stable than the analogous A-type sandwich polyoxometalates containing divalent metals. PMID:14686830

Fang, Xikui; Anderson, Travis M; Neiwert, Wade A; Hill, Craig L

2003-12-29

61

Sorption of yttrium and rare earth elements by amorphous ferric hydroxide: Influence of solution complexation with carbonate  

NASA Astrophysics Data System (ADS)

The influence of solution complexation on the sorption of yttrium and the rare earth elements (YREEs) by amorphous ferric hydroxide was investigated at 25 C over a range of pH (4.0-7.1) and carbonate concentrations (0M?[CO32-]?150?M). Distribution coefficients, defined as iKFeT=[MS]/(M[S]), where [MS i] T is the total concentration of sorbed YREE, M T is the total YREE concentration in solution, and [S i] is the concentration of amorphous ferric hydroxide, initially increased in magnitude with increasing carbonate concentration, and then decreased. The initial increase of iKFeT is due to sorption of YREE carbonate complexes (MCO3+), in addition to sorption of free YREE ions (M 3+). The subsequent decrease of iKFeT, which is more extensive for the heavy REEs, is due to the increasing intensity of YREE solution complexation by carbonate ions. The competition for YREEs between solution complexation and surface complexation was modeled via the equation: iKFeT={(S?1[H]-1+S?2[H]-2+?1S}/{CO?1COH[HCO3-][H]-2)(SK1[H]+1)(1+HCO?1[HCO3-]+?1COH[HCO3-][H]-1+?2COH[HCO3-]T2[H]-2)} where S?1 and S?2 are equilibrium constants for free YREE surface species, ?1SCO is the equilibrium constant for the YREE-carbonate surface species, SK1 is the surface protonation constant for amorphous ferric hydroxide, and HCO?1, ?1COH, and ?2COH are YREE solution complexation constants expressed in terms of bicarbonate concentrations. The equation, which includes (i) a single new constant (?1SCO) for each YREE, (ii) previously published sorption coefficients ( S?1 and S?2) determined in the absence of carbonate, and (iii) previously published solution complexation constants, precisely predicts both the absolute magnitude of iKFeT and the pattern of iKFeT values over our range of experimental conditions. Experimentally observed iKFeT values, spanning more than five orders of magnitude, are accurately described by our surface/solution complexation model. The log?1SCOvalues determined for each YREE in this work are: Y(-1.30 0.04), La(-0.39 0.02), Ce(-0.21 0.02), Pr(-0.22 0.02), Nd(-0.20 0.02), Sm(-0.20 0.02), Eu(-0.26 0.02), Gd(-0.38 0.02), Tb(-0.40 0.02), Dy(-0.51 0.02), Ho(-0.57 0.02), Er(-0.59 0.02), Tm(-0.56 0.02), Yb(-0.62 0.02), and Lu(-0.59 0.02).

Quinn, Kelly A.; Byrne, Robert H.; Schijf, Johan

2006-08-01

62

Process for removing carbon from uranium  

DOEpatents

Carbon contamination is removed from uranium and uranium alloys by heating in inert atmosphere to 700.degree.-1900.degree.C in effective contact with yttrium to cause carbon in the uranium to react with the yttrium. The yttrium is either in direct contact with the contaminated uranium or in indirect contact by means of an intermediate transport medium.

Powell, George L. (Oak Ridge, TN); Holcombe, Jr., Cressie E. (Knoxville, TN)

1976-01-01

63

Generation, properties, and order packing of monodispersed spherical colloid particles of yttrium hydroxy-carbonate: A colloidal route to minimizing voids in ceramics  

SciTech Connect

Yttrium hydroxy-carbonate particles were prepared by decomposition of urea in yttrium nitrate solutions. The nucleation and growth were studied in silica-seeded and unseeded systems. Precipitation took place only under neutral conditions. In unseeded systems, homogeneous nucleation yielded 3 x 10/sup 10/ nucleicm/sup 3/ while in seeded precipitation enough nuclei were produced to bring the total number of particles to 4 x 10/sup 10/cm/sup 3/. Systems containing at least 4 x 10/sup 10/ seedscm/sup 3/ underwent pure heterogeneous precipitation onto the existing seeds. Two diffusion-controlled growth models and the diffusion chronomal analysis were applied to the data of growth rate. Results confirmed the diffusion-controlled particle growth mechanism. Electron diffraction showed the particles to be crystalline. Electrophoresis showed a charge reversal from positive to negative with pH, with an isoelectric point of about 7.4. The chemical composition of the powders was determined to be Y(OH)CO/sub 3/ . H/sub 2/O. Stability of aqueous suspensions was studied as a function of pH. 74 refs., 27 figs., 3 tabs

Mwesigwa-Kayima, P.

1987-11-01

64

89Y and 13C NMR cluster and carbon cage studies of an yttrium metallofullerene family, Y3N@C(2n) (n = 40-43).  

PubMed

The members of a new family of yttrium trimetallic nitride-templated (TNT) endohedral metallofullerenes (EMFs), Y(3)N@C(2n) (n = 40-43), have been synthesized and purified. On the basis of experimental and computational (13)C NMR studies, we propose cage structures for Y(3)N@I(h)-C(80) (IPR allowed), Y(3)N@D(5h)-C(80) (IPR allowed), Y(3)N@C(s)-C(82) (non-IPR), Y(3)N@C(s)-C(84) (non-IPR), and Y(3)N@D(3)-C(86) (IPR allowed). A significant result is the limited number of isomers found for each carbon cage. For example, there are 24 isolated pentagon rule (IPR) and 51 568 non-IPR structures possible for the C(84) cage, but only one major isomer of Y(3)N@C(s)-C(84) was found. The current study confirms the unique role of the trimetallic nitride (M(3)N)(6+) cluster template in the Kratschmer-Huffman electric-arc process for fullerene cage size and high symmetry isomer selectivity. This study reports the first (89)Y NMR results for Y(3)N@I(h)-C(80,) Y(3)N@C(s)(51365)-C(84), and Y(3)N@D(3)(19)-C(86), which reveal a progression from isotropic to restricted (Y(3)N)(6+) cluster motional processes. Even more surprising is the sensitivity of the (89)Y NMR chemical shift parameter to subtle changes in the electronic environment at each yttrium nuclide in the (Y(3)N)(6+) cluster (more than 200 ppm for these EMFs). This (89)Y NMR study suggests that (89)Y NMR will evolve as a powerful tool for cluster motional studies of EMFs. PMID:19639998

Fu, Wujun; Xu, Liaosa; Azurmendi, Hugo; Ge, Jiechao; Fuhrer, Tim; Zuo, Tianming; Reid, Jonathan; Shu, Chunying; Harich, Kim; Dorn, Harry C

2009-08-26

65

CoPrecipitation of Double Carbonates of Yttrium and the Rare Earth Elements, Na2xM2(CO3)3+x, from Seawater-Like Electrolyte Solutions  

Microsoft Academic Search

Co-precipitation of mixed carbonates of yttrium and the rare earth elements (YREEs) from perchlorate and chloride solutions at seawater ionic strength (0.7 molal, T = 25C) was induced by raising pH under an atmosphere of 100% CO2. Solution pH was monitored with a glass combination electrode, and dissolved YREE concentrations by ICP-MS after filtration through 0.2 mum pore size membranes.

J. Schijf; R. H. Byrne

2010-01-01

66

Carbon spheres  

Microsoft Academic Search

The discovery of fullerenes has opened up new studies in shaped carbon materials. In particular the discovery that carbon atoms in fullerenes showed curved sp2 bonding also led to the discovery of single walled carbon nanotubes and a re-investigation of carbon fibers and tubes. The area of shaped carbon materials has since been dominated by studies of carbon nanotubes. The

Amit A. Deshmukh; Sabelo D. Mhlanga; Neil J. Coville

2010-01-01

67

Carbon-Carbon Materials - Carbon Composites Materiaux Carbone-Carbone Composites Carbones.  

National Technical Information Service (NTIS)

The application of carbon based materials in solid propellant rocket engine nozzles is discussed. Considered are polycrystalline graphites, pyrographite, carbon reinforced phenolic composites, and carbon-carbon composites. The importance of sepcarb (carbo...

C. Choury

1977-01-01

68

carbon cycle  

NSDL National Science Digital Library

Life on earth is based on carbon. Living things acquire carbon from their environment - from air, water, soil, and rock and from other living things - through processes such as photosynthesis, respiration and decomposition. The carbon cycle model is a representation of the movement of carbon from sources to sinks through chemical and physical transfers. The carbon cycle activity allows students to see the effect of fossil fuel burning on the carbon cycle.

School, Maryland V.

69

Carbon Smackdown: Carbon Capture  

ScienceCinema

In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

70

Virtuous carbon  

Microsoft Academic Search

To provides an overall framework for thinking about the construction of carbon markets, we adopt James Der Derian's virtuous war theory to develop an argument about carbon as a virtuous commodity. This refers to the close affinity between virtuality and virtue the technological and the ethical in the construction of carbon markets. The figure of virtuous carbon draws

Matthew Paterson; Johannes Stripple

2012-01-01

71

Carbon Dioxide Disposal via Carbonation  

Microsoft Academic Search

Carbonation is a solidification\\/stabilization process. The availability of a carbon dioxide (CO2) fixation technology would serve as insurance in case global warming causes severe restrictions on CO2 emissions. In order to prevent rapid climate change, it will be necessary to stabilize CO2 as carbonate by the carbonation process. Carbonation of the widely occurring mineral olivine (Mg2SiO4) converts CO2 into an

A. Demirbas

2007-01-01

72

Carbon cycle: Nitrogen's carbon bonus  

NASA Astrophysics Data System (ADS)

Atmospheric deposition of nitrogen can, but does not always, speed up the sequestration of carbon in trees and forest soil. This complexity may arise from the spatial variations in each of the three mechanisms by which nitrogen affects carbon storage.

Janssens, Ivan A.; Luyssaert, Sebastiaan

2009-05-01

73

CARBON MONOXIDE  

EPA Science Inventory

This document summarizes the carbon monoxide literature related to effects on man and his environment for the consideration of the Environmental Protection Agency in updating the information in the Air Quality Criteria for Carbon Monoxide. It emphasizes recent major advances in o...

74

Block copolymerization of carbon dioxide with cyclohexene oxide and 4-vinyl-1-cyclohexene-1,2-epoxide in based poly(propylene carbonate) by yttriummetal coordination catalyst  

Microsoft Academic Search

The coordination system, Y(CF3CO2)3 (I)Zn(Et)2 (II)m-hydroxybenzoic acid (III), was found to be the most active catalyst to generate poly(propylene carbonate) (PPC) from carbon dioxide and propylene oxide (PO) in 1,3-dioxolane. A high yield and a high molecular weight could be obtained at the conditions of a II\\/I molar ratio of 20, a III\\/II molar ratio of 1.0, a temperature of

Tsung-Ju Hsu; Chung-Sung Tan

2002-01-01

75

Resistivity of Carbon-Carbon Composites Halved.  

National Technical Information Service (NTIS)

Carbon-carbon composites have become the material of choice for applications requiring strength and stiffness at very high temperatures (above 2000 C). These composites comprise carbon or graphite fibers embedded in a carbonized or graphitized matrix. In ...

J. R. Gaier

2004-01-01

76

Co-Precipitation of Double Carbonates of Yttrium and the Rare Earth Elements, Na2xM2(CO3)3+x, from Seawater-Like Electrolyte Solutions  

NASA Astrophysics Data System (ADS)

Co-precipitation of mixed carbonates of yttrium and the rare earth elements (YREEs) from perchlorate and chloride solutions at seawater ionic strength (0.7 molal, T = 25C) was induced by raising pH under an atmosphere of 100% CO2. Solution pH was monitored with a glass combination electrode, and dissolved YREE concentrations by ICP-MS after filtration through 0.2 ?m pore size membranes. Experiments were conducted (a) in NaClO4 and NaCl with equimolar YREE mixtures (all 1 mM); (b) in NaClO4 with equimolar YREE mixtures (10 ?M) plus 1 mM Sm; and (c) with pure Sm and Yb solutions (10 mM). The applied pH range (4-8) resulted in a nearly 7 orders of magnitude variation of the free carbonate concentration. Double-logarithmic plots of individual YREE concentrations as a function of the free carbonate concentration are highly linear for all experiments, whereby the slopes represent carbonate:YREE ratios of the saturated solutions in equilibrium with the mixed co-precipitates, for each element. In virtually all cases (except for Y, Yb, and Lu in the equimolar mixture and Lu in the Sm-enriched mixture, both in NaClO4) the observed slopes are significantly larger than 1.5, the value expected for pure YREE carbonates (x = 0). The higher values suggest missing positive charge, which must be supplied by Na+, the only other positive ion in the solutions. Double carbonates of the form NaM(CO3)2 have long been known as the least soluble YREE salts in Na-rich solutions, yet their role in YREE geochemical cycles has been largely ignored. In addition, studies of their solubilities have focused mainly on precipitates of single YREEs, which do not occur in nature. The stoichiometry of the mixed co-precipitates appears quite complicated and variable. The pure Sm and Yb precipitates yield slopes of ~1.6, indicating minor incorporation of Na+. The mixed co-precipitate formed in NaClO4 yields slopes that smoothly vary from ~1.5 for Y and Lu to a maximum of ~1.8 for Sm. In NaCl the slopes are about 0.1 units higher and the maximum is shifted to slightly heavier elements, possibly due to YREE-chloride complexation. In the Sm-enriched co-precipitate the slopes range from ~1.5 for Lu to ~2.0 for Dy, displaying substantially more structure as a function of atomic number. Ion concentration products, calculated from the inferred stoichiometries, are similar in magnitude to published solubility products for the pure carbonates of single YREEs but show distinctly different patterns across the YREE series. These results could have a profound impact on interpretations of the pH-dependent incorporation of YREEs in marine carbonates, such as coral skeletons and pteropod shells, which are generally based on the solubility products of single-YREE carbonates precipitated from Na-free solutions. YREE abundance patterns and Nd isotope ratios in biominerals are likely to be increasingly used in studies of paleo-ocean circulation patterns, coastal inputs of dust due to mining and deforestation, and possibly ocean acidification.

Schijf, J.; Byrne, R. H.

2010-12-01

77

Carbon-Carbon Materials and Composites.  

National Technical Information Service (NTIS)

Carbon-fiber-reinforced carbon matrix (carbon-carbon) composites have received increasing emphasis over the past 15 years. These materials have been used primarily in the aerospace and automotive industries. Carbon-carbon composites can be made in a wide ...

D. D. Edie J. D. Buckley

1992-01-01

78

Carbon sequestration.  

PubMed

Developing technologies to reduce the rate of increase of atmospheric concentration of carbon dioxide (CO2) from annual emissions of 8.6PgCyr-1 from energy, process industry, land-use conversion and soil cultivation is an important issue of the twenty-first century. Of the three options of reducing the global energy use, developing low or no-carbon fuel and sequestering emissions, this manuscript describes processes for carbon (CO2) sequestration and discusses abiotic and biotic technologies. Carbon sequestration implies transfer of atmospheric CO2 into other long-lived global pools including oceanic, pedologic, biotic and geological strata to reduce the net rate of increase in atmospheric CO2. Engineering techniques of CO2 injection in deep ocean, geological strata, old coal mines and oil wells, and saline aquifers along with mineral carbonation of CO2 constitute abiotic techniques. These techniques have a large potential of thousands of Pg, are expensive, have leakage risks and may be available for routine use by 2025 and beyond. In comparison, biotic techniques are natural and cost-effective processes, have numerous ancillary benefits, are immediately applicable but have finite sink capacity. Biotic and abiotic C sequestration options have specific nitches, are complementary, and have potential to mitigate the climate change risks. PMID:17761468

Lal, Rattan

2008-02-27

79

Manual of carbonate sedimentology  

SciTech Connect

This manual, organised along encycolopaedic/lexicographic lines, summarizes information on the properties and characteristics of carbonates and their environments. Part 1 deals with the elements of carbonates; Part 2 with environments, settings, and carbonate bodies; Part 3 with carbonate diagenesis, and Part 4 with carbonate reservoirs. Contents include: Elements of carbonates; Carbonate Environments, Settings and Bodies; Carbonate diagenesis; Carbonate reservoirs; Alphabetical Indices; English, Dutch, German, Spanish, French Computer Compatible Codes; Commonly Used (Informal) abbreviations.

Reijers, T.J.; Hsu, K.S.

1986-01-01

80

Carbon particles  

DOEpatents

A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.

Hunt, Arlon J. (Oakland, CA)

1984-01-01

81

Carbon Temperature Model  

NSDL National Science Digital Library

With this carbon/temperature interactive model, students investigate the role of atmospheric carbon in the greenhouse effect using a relationship between atmospheric carbon dioxide and global temperature.

Center, Nasa: C.; Nasa

82

Carbon Nanoelectronics  

NASA Astrophysics Data System (ADS)

Recently, there has been tremendous interest in nanostructures built entirely out of carbon. The most famous are the soccer-ball shaped C60 molecule and single-walled nanotubes. The latter are nanometer-diameter cylinders made from rolled up single graphene sheets. These carbon nanostructures are proving to be wonderful systems for the study of the physics of electrons in reduced dimensions. They also have a variety of technological applications (both demonstrated and potential), in areas ranging from materials to electronics to biotechnology. In this talk, I will discuss our group's recent efforts to probe the electrical and electromechanical, and thermal properties of these fascinating systems. note

McEuen, Paul

2001-05-01

83

Carbon microtubes  

SciTech Connect

A carbon microtube comprising a hollow, substantially tubular structure having a porous wall, wherein the microtube has a diameter of from about 10 .mu.m to about 150 .mu.m, and a density of less than 20 mg/cm.sup.3. Also described is a carbon microtube, having a diameter of at least 10 .mu.m and comprising a hollow, substantially tubular structure having a porous wall, wherein the porous wall comprises a plurality of voids, said voids substantially parallel to the length of the microtube, and defined by an inner surface, an outer surface, and a shared surface separating two adjacent voids.

Peng, Huisheng (Shanghai, CN); Zhu, Yuntian Theodore (Cary, NC); Peterson, Dean E. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)

2011-06-14

84

Black Carbon  

NSDL National Science Digital Library

Black carbon, composed of tiny particles of soot, is produced whenever organic substances like fossil fuels, firewood or coal is incompletely burned. These particles are polluting the air and causing serious health and environmental concerns for people around the world. "Changing Planet" is produced in partnership with the National Science Foundation.

Learn, Nbc

2010-10-07

85

Carbon dioxide  

NSDL National Science Digital Library

Bubbles are an indicator of a chemical reaction. An indicator is an object, material, or organism that tells you if a specific substance is present. In the sugar test, carbon dioxide gas release is an indicator that yeast is using sugar to grow. The more gas produced, the more sugar a specific substance contains.

Arie Melamed-Katz (None;)

2007-06-19

86

Carbon supercapacitors.  

National Technical Information Service (NTIS)

Carbon supercapacitors are represented as distributed RC networks with transmission line equivalent circuits. At low charge/discharge rates and low frequencies these networks approximate a simple series R(sub ESR)C circuit. The energy efficiency of the su...

F. M. Delnick

1993-01-01

87

Carbon disulphide  

Microsoft Academic Search

Summary Carbon disulphide (CS2), a reagent of rayon production, is known for its high toxic potential and has therefore been the subject of many clinical studies. The aims of the study presented here were to determine the effective exposure to CS2 and to compare the validity of the different exposure indicators. Internal and external exposure to CS2 was investigated in

H. Drexler; Th. Gen; J. Angerer; S. Abou-el-ela; G. Lehnert

1994-01-01

88

Carbon-carbon piston development. Final report  

Microsoft Academic Search

A new piston concept, made of carbon-carbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon material, developed in the early 1960's, is lighter in weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500 F. In addition, carbon-carbon material has a low coefficient of

Gorton

1994-01-01

89

Carbon Cycle  

NSDL National Science Digital Library

Elementary students often successfully memorize and repeat back the stages in cycles, with no deep conceptual understanding of the complexities of the processes involved. Their ability to synthesize knowledge of the cycles with a wider breadth of information related to real-world, unresolved environmental issues such as global warming, greenhouse gas emissions or the burning of biomass for fuel is probably less well developed. In order to engage in meaningful discussions of carbon-related environmental issues, students also need an understanding of the changing nature of the earth s atmosphere. The relative proportion of nitrogen, carbon dioxide, oxygen, ozone and other gases is neither consistent around the world nor constant over time. What factors contribute to the variability in atmospheric content? Which of the factors should be controlled? What are the possible approaches to controlling them? What are the possible and probable outcomes of such controlling measures?

Lefever, Mary

2007-01-01

90

Molecular Structure of Carbonate ion  

NSDL National Science Digital Library

Carbonates were studied extensively by geologists. Common carbonate-containing geologic materials are barium calcium carbonate, lead carbonate, and strontium carbonate. Carbonate is the salt of carbonic acid. Many counter ions are possible, including calcium carbonate and barium carbonate. Calcium carbonate is a brittle white rock, used in many buildings. Lithium carbonate is used to treat manic phases for bipolar disorder/manic depression. Carbonic acid is found in carbonated beverages, giving them a tart flavor.

2002-09-18

91

Carbon investment funds  

SciTech Connect

The report is a study of the development of funds to invest in the purchase of carbon credits. It takes a look at the growing market for carbon credits, the rise of carbon investment funds, and the current state of carbon investing. Topics covered in the report include: Overview of climate change, greenhouse gases, and the Kyoto Protocols. Analysis of the alternatives for reducing carbon emissions including nitrous oxide reduction, coal mine methane capture and carbon capture and storage; Discussion of the different types of carbon credits; Discussion of the basics of carbon trading; Evaluation of the current status of carbon investing; and Profiles of 37 major carbon investment funds worldwide.

NONE

2007-01-15

92

Circumferentially Wrapped Carbon-Carbon Structure.  

National Technical Information Service (NTIS)

A carbon-carbon structure useful for fabricating a nosetip for a reentry vehicle, which consists essentially of a central core, a plurality of layers of woven carbon fabric circumferentially wrapped around the core, and a carbon binder, wherein the core c...

G. A. Wallace J. E. Zimmer

1984-01-01

93

Method of making carbon-carbon composites  

Microsoft Academic Search

A process for making 2D and 3D carbon-carbon composites having a combined high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus\\/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizible woven cloth are infiltrated with carbon material to form green composites. The carbonized composite is then impregnated several times with

Engle; Glen B

1993-01-01

94

Carbon Nitride and Boron Carbon Nitride Nanostructures  

Microsoft Academic Search

This chapter is devoted to carbon nitride and boron carbon nitride nanostructures, an important and indispensable member in\\u000a the family of nanomaterials for various applications, especially in nanoelectronics. It covers all the main aspects of the\\u000a current research on the carbon nitride and boron carbonitride nanostructures. The attention is mainly focused on the one-dimensional\\u000a carbon nitride and boron carbon nitride

Jie Yu; E. G. Wang

95

Carbon Cycle: Where Is This Crucial Carbon?  

NSDL National Science Digital Library

This demonstration aims to teach students about the nature of carbon, the different types of compounds it exists in (e.g. charcoal, glucose, carbon dioxide), the biochemical reactions it takes part in (photosynthesis and respiration), the range of processes that carbon and carbon compounds are involved in on Earth, and how these link together to form the carbon cycle. Students will be reminded that carbon is the fundamental building block of life (the element that life is based on). They will discover that carbon is contained in everything from fossil fuels to DNA and is cycled and re-cycled through the carbon cycle. Students will also understand that both animals and plants need carbon although they obtain it in different ways. This site has teacher notes and directions, suggested questions with answers, a list of required materials, and a glossary.

96

Trading forest carbon  

EPA Science Inventory

The nature of carbon in forests is discussed from the perspective of carbon trading. Carbon inventories, specifically in the area of land use and forestry are reviewed for the Pacific Northwest. Carbon turnover in forests is discussed as it relates to carbon sequestration. Scient...

97

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

98

Method of making carbon-carbon composites  

DOEpatents

A process for making 2D and 3D carbon-carbon composites having a combined high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizible woven cloth are infiltrated with carbon material to form green composites. The carbonized composite is then impregnated several times with pitch by covering the composite with hot pitch under pressure. The composites are given a heat treatment between each impregnant step to crack up the infiltrated carbon and allow additional pitch to enter the microstructure during the next impregnation cycle. The impregnated composites are then given a final heat treatment in the range 2500.degree. to 3100.degree. C. to fully graphitize the fibers and the matrix carbon. The composites are then infiltrated with pyrolytic carbon by chemical vapor deposition in the range 1000.degree. C. to 1300.degree. C. at a reduced. pressure.

Engle, Glen B. (16716 Martincoit Rd., Poway, CA 92064)

1993-01-01

99

Carbon nanotube cathode with capping carbon nanosheet  

NASA Astrophysics Data System (ADS)

Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500 ?/? to 300 ?/? when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.

Li, Xin; Zhao, Dengchao; Pang, Kaige; Pang, Junchao; Liu, Weihua; Liu, Hongzhong; Wang, Xiaoli

2013-10-01

100

Radiation damage in carbon-carbon composites  

Microsoft Academic Search

Graphite and carbon-carbon composite materials are widely used in plasma facing applications in current Tokamak devices such as TFTR and DIIID in the USA, JET, Tore Supra and TEXTOR in Europe, and JT-60U in Japan. Carbon-carbon composites are attractive choices for Tokamak limiters and diverters because of their low atomic number, high thermal shock resistance, high melting point, and high

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

1992-01-01

101

Carbon structures in silicon carbide derived carbon  

Microsoft Academic Search

Carbide derived carbon (CDC) produced by etching SiC in halogens has been investigated using transmission electron microscopy (TEM). Depending on experimental conditions, CDC may contain sp3- or sp2-bonded carbon phases. Amorphous carbon, poorly ordered turbostratic carbon with lattice spacing exceeding values of 0.35nm as well as highly ordered graphite were observed. sp3-Bonded structures consist of mainly lonsdaleite and cubic diamond

Sascha Welz; Michael J. McNallan; Yury Gogotsi

2006-01-01

102

Carbon Capture (Carbon Cycle 2.0)  

SciTech Connect

Berend Smit speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 3, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

Smit, Berend

2010-02-03

103

Interpreting carbon-isotope excursions: carbonates and organic matter  

Microsoft Academic Search

Variations in the carbon isotopic compositions of marine carbonate and organic carbon provide a record of changes in the fraction of organic carbon buried through time and may provide clues to changes in rates of weathering and sources of organic carbon. Paired carbonate and organic carbon isotope determinations provide a possibility of interpreting not only changes in the global carbon

Lee R. Kump; Michael A. Arthur

1999-01-01

104

Carbon monoxide  

PubMed Central

Carbon monoxide (CO), a by-product released during the degradation of heme by heme oxygenases (HOS EC 1.14.99.3) in animals, plays a major role as neurotransmitter, regulator of sinusoidal tone, inhibitor of platelet aggregation and suppressor of acute hypertensive response, and most of above effects are similar to or mediated by nitric oxide (NO), another signal molecule in both the animal and plant kingdoms. Previous result demonstrated that NO could act as a promoter of plant cell elongation, acting similarly to IAA, inducing morphogenetic responses leading to expansion in plant tissues. Recent observations revealed that CO is an inducer of cell expansion in wheat root segments, acting similarly to IAA and NO. Evidence also indicated that IAA could result in either the potent induction of HO-1 transcript or endogenous CO releasing in wheat root segments. Additionally, our results suggested that above CO signaling might be related to NO/cGMP, Ca2+ and even ROS-dependent pathways. In this addendum, combined with other previous results, we further proposed a possible hypothesis for CO signaling role in regulation of plant root development induced by auxin.

Xuan, Wei; Xu, Sheng; Yuan, Xingxing

2008-01-01

105

Carbon nanotube arrays  

Microsoft Academic Search

Carbon nanotube arrays were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. The effect of substrates on the growth, morphology and structure of carbon nanotubes were investigated. Aligned carbon nanotubes with high density and purity were achieved by CVD on bulk silica substrate. On the film-like substrates, very long carbon nanotubes of length ~2mm were produced,

S. S. Xie; W. Z. Li; Z. W. Pan; B. H. Chang; L. F. Sun

1999-01-01

106

Composition of carbonization residues  

Microsoft Academic Search

This report compared the composition of samples from Wesseling and Leuna. In each case the sample was a residue from carbonization of the residues from hydrogenation of the brown coal processed at the plant. The composition was given in terms of volatile components, fixed carbon, ash, water, carbon, hydrogen, oxygen, nitrogen, volatile sulfur, and total sulfur. The result of carbonization

Hupfer; Leonhardt

1943-01-01

107

Dynamic carbon footprinting  

Microsoft Academic Search

The early focus by individual businesses on the reduction of their own carbon footprint is being superseded by a phase of building carbon-constrained business networks. Across these networks, businesses evaluate each others' footprints and conduct business accordingly. Dynamic carbon footprinting is emerging as a powerful tool for guiding operational logic and business transformation into the carbon-constrained markets, with delivery of

Michael Gell

2008-01-01

108

Acetylenic carbon allotrope  

SciTech Connect

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

NONE

1999-11-16

109

Templated nanoscale porous carbons  

Microsoft Academic Search

This manuscript reviews key developments in the important and rapidly expanding area of templated porous carbons. The porosity covered ranges from microporous to mesoporous and macroporous carbons. Two modes of templating, using so-called hard and soft templates, are covered. In particular, for hard templating, zeolite templating generates microporous carbons, mesoporous silicates yield mesoporous carbons, while colloidal particles are replicated to

Yongde Xia; Zhuxian Yang; Robert Mokaya

2010-01-01

110

Hyperpolarized carbon - carbon intermolecular multiple quantum coherences  

PubMed Central

Intermolecular multiple quantum coherences (iMQCs) can provide unique contrast with sub-voxel resolution. However, the characteristic growth rate of iMQCs mostly limits these effects to either hydrogen or hydrogen-coupled systems for thermally polarized samples. Hyperpolarization techniques such as dynamic nuclear polarization (DNP) allow for significant increases in the carbon signal (even more signal than that from hydrogen), making carbon iMQCs achievable. We present the first intermolecular multiple quantum signal between two carbon nuclei.

Jenista, Elizabeth R.; Branca, Rosa T.; Warren, Warren S.

2009-01-01

111

Method of making carbon-carbon composites  

Microsoft Academic Search

A process for making a carbon-carbon composite having a combination of high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus\\/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizable woven cloth are covered with petroleum or coal tar pitch and pressed at a temperature a few degrees above the softening

Engle; Glen B

1991-01-01

112

Method of making carbon-carbon composites  

Microsoft Academic Search

A process is described for making a carbon-carbon composite having a combination of high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus\\/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizable woven cloth are covered with petroleum or coal tar pitch and pressed at a temperature a few degrees above

Engle

1991-01-01

113

Carbon Dioxide Emissions and Carbonation Sensors  

Microsoft Academic Search

The gases with higher heat capacities than those of O2 and N2 cause greenhouse effects. Carbon dioxide (CO2) is the main greenhouse gas associated with global climate change. At the present time, coal is responsible for 3040% of world CO2 emissions from fossil fuels. There was a higher correlation between the amount of carbon dioxide emission and percentage of carbon

A. Demirbas

2007-01-01

114

Carbon Nanocapsules Grown on Carbon Fibers  

NASA Astrophysics Data System (ADS)

Carbon nanocapsules grown on pitch-based carbon fibers were investigated by high-resolution electron microscopy. It was found that they were formed during heating up to 2000 C in 1 atm N2 gas. Two types of nanocapsules were found: one was a capsule enclosing a CaS single crystal and the other was a cubic hollow capsule. The growth mechanism of these carbon nanocapsules was discussed by comparing the structures of particles formed at several temperatures.

Kusunoki, Michiko; Ikuhara, Yuichi; Kon, Jun-ichi

1995-03-01

115

Carbonate associated with hydroxide sol-gel processing of yttria: An infrared spectroscopic study  

SciTech Connect

Yttrium hydroxide gel was dried by five techniques to study their influences on the sintering behavior of yttria. Dried precursors, calcined and sintered oxides, and the initial gel were examined via Fourier transform infrared photoacoustic and/or attenuated total reflection spectroscopies. Carbonate was found to be in unidentate coordination to surface yttrium on both the dried hydroxide precursor and calcined oxide particles. An inverse correlation was found between the normalized surface carbonate concentration (carbonate concentration (wt%)/surface area (m/sup 2//g)) of precursors and calcined oxides and the density of their corresponding sintered bodies. Carbonate affects sintered density during the calcination and sintering steps.

Seaverson, L.M.; Luo, S.Q.; Chien, P.L.; McClelland, J.F.

1986-05-01

116

Modern carbonate environments  

SciTech Connect

This book offers help in evaluating potential sites for oil and gas accumulations. Pointing the way to discovery of hydrocarbons in carbonate reservoirs, this volume discusses modern carbonate depositional environments in different geomorphic settings. It compiles papers by scientists whose observations have revolutionized current thinking on facies relationships in ancient carbonate rock. Contents include: Selected carbonate regions --The Algal Sediments on Androa Island in the Bahamas, Sedimentary Facies, Interaction of Genetic Processes in Holocene Reefs off North Eleuthera Island in the Bahamas, Recent Anhydrite, Holocene Shallow-Water Carbonate and Evaporite Sediments of Khor al Bazam; Carbonate production--On the Origin of Aragonite in the Dead Sea, Carbonate Production by Coral Reefs; Cold-water carbonates--Contributions on the Geology of the Northwestern Peninsula of Iceland, Evaluation of Cold-Water Carbonates as a Possible Paleoclimatic Indicator.

Bhattacharyya, A.; Friedman, G.M.

1983-01-01

117

Carbon fuel cells with carbon corrosion suppression  

SciTech Connect

An electrochemical cell apparatus that can operate as either a fuel cell or a battery includes a cathode compartment, an anode compartment operatively connected to the cathode compartment, and a carbon fuel cell section connected to the anode compartment and the cathode compartment. An effusion plate is operatively positioned adjacent the anode compartment or the cathode compartment. The effusion plate allows passage of carbon dioxide. Carbon dioxide exhaust channels are operatively positioned in the electrochemical cell to direct the carbon dioxide from the electrochemical cell.

Cooper, John F. (Oakland, CA)

2012-04-10

118

Evaluation of Characterization Techniques for Carbon-Carbon Composites.  

National Technical Information Service (NTIS)

Characterization techniques for organic/inorganic composites are well established and documented; however, this is not the case regarding carbon-carbon composites. Due to expansion of the Materials Directorate in-house carbon-carbon composite research eff...

W. Ragland

1992-01-01

119

Absorption of Carbon Dioxide on Carbonic Anhydrase Containing Substrates.  

National Technical Information Service (NTIS)

Carbonic anhydrase (CA), an enzyme catalyzing carbon dioxide hydration, was evaluated for its enhancement of carbon dioxide removal when it is present in granular materials with high water content during exposure to carbon dioxide in an aerating stream. A...

J. P. Allen

1968-01-01

120

Laser Cladding on Carbon-Carbon Composites.  

National Technical Information Service (NTIS)

This report describes the results of experiments on laser cladding a variety of protective coatings onto carbon-carbon substrates as oxidation- protection coatings. The work was performed using a 12-kW flattop CO2 laser and a powder delivery system to inj...

J. J. Eric R. J. Hull

2002-01-01

121

Method of making carbon-carbon composites  

DOEpatents

A process for making a carbon-carbon composite having a combination of high crystallinity, high strength, high modulus and high thermal and electrical conductivity. High-modulus/high-strength mesophase derived carbon fibers are woven into a suitable cloth. Layers of this easily graphitizable woven cloth are covered with petroleum or coal tar pitch and pressed at a temperature a few degrees above the softening point of the pitch to form a green laminated composite. The green composite is restrained in a suitable fixture and heated slowly to carbonize the pitch binder. The carbonized composite is then impregnated several times with pitch by covering the composite with hot pitch under pressure. The composites are given a heat treatment between each impregnation step to crack up the infiltrated carbon and allow additional pitch to enter the microstructure during the next impregnation cycle. The impregnated composites are then given a final heat treatment in the range 2500.degree. to 3000.degree. C. to fully graphitize the fibers and the matrix carbon. The composites are then infiltrated with pyrolytic carbon by chemical vapor deposition in the range 1000.degree. to 1300.degree. C. at a reduced pressure for approximately one hundred and fifty (150) hours.

Engle, Glen B. (16716 Martincoit Rd., Poway, CA 92064)

1991-01-01

122

T-carbon: a novel carbon allotrope.  

PubMed

A structurally stable crystalline carbon allotrope is predicted by means of the first-principles calculations. This allotrope can be derived by substituting each atom in diamond with a carbon tetrahedron, and possesses the same space group Fd3m as diamond, which is thus coined as T-carbon. The calculations on geometrical, vibrational, and electronic properties reveal that T-carbon, with a considerable structural stability and a much lower density 1.50??g/cm3, is a semiconductor with a direct band gap about 3.0 eV, and has a Vickers hardness 61.1 GPa lower than diamond but comparable with cubic boron nitride. Such a form of carbon, once obtained, would have wide applications in photocatalysis, adsorption, hydrogen storage, and aerospace materials. PMID:21568576

Sheng, Xian-Lei; Yan, Qing-Bo; Ye, Fei; Zheng, Qing-Rong; Su, Gang

2011-04-15

123

When carbon footprints hop  

NASA Astrophysics Data System (ADS)

Despite having achieved legally binding commitments on emissions reductions, many countries have increased their appetite for carbon-intensive products, making up the difference through international trade. Anna Petherick reports on the sticky task of regulating these invisible carbon flows.

Petherick, Anna

2012-07-01

124

Trading forest carbon - OSU  

EPA Science Inventory

Issues associate with trading carbon sequestered in forests are discussed. Scientific uncertainties associated with carbon measurement are discussed with respect to proposed accounting procedures. Major issues include: (1) Establishing baselines. (2) Determining additivity from f...

125

Sodium carbonate poisoning  

MedlinePLUS

Sodium carbonate (also known as washing soda or soda ash) is a chemical found in many household ... products. This article focuses on poisoning due to sodium carbonate. This is for information only and not ...

126

Potassium carbonate poisoning  

MedlinePLUS

Potassium carbonate is a white powder used to make soap, glass, and other items. This article discusses poisoning from swallowing or breathing in potassium carbonate. This is for information only and not ...

127

Microbially mediated mineral carbonation  

Microsoft Academic Search

Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O --> (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate

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

2010-01-01

128

Carbon Cycle Roleplay  

NSDL National Science Digital Library

In this creative roleplay activity, learners will explore the various processes of the carbon cycle using movement and props to aid in comprehension. Learners will understand that carbon changes forms throughout the carbon cycle, and that carbon is continuously moving throughout all the cycles at the same time. This standards-based lesson, which is great for the classroom, camps, or afterschool programs, includes roleplay cards and ideas for props.

Sciences, California A.

2008-01-01

129

Understanding the Carbon Cycle  

NSDL National Science Digital Library

In this unit, students use Internet resources, slide presentations, and modeling to explain how understanding the carbon cycle helps scientists understand and prepare for global climate change, what might happen if sources of carbon produced more than sinks could remove, and what might happen if sinks absorbed more than sources produced. They should understand how the carbon cycle affects various life forms and the role that carbon plays in their lives. Procedures, a glossary, assessments, and scoring rubrics are provided.

130

Functionalization of carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes have unique properties that make them attractive for different engineering applications. However, because of their chemical inertness, carbon nanotubes have to be functionalized in order to acquire additional physico-chemical properties. Large multiwalled carbon nanotubes are different from fullerenes and singlewalled nanotubes because the stresses in their walls are almost relaxed while most chemical methods for fullerene functionalization exploit

Guzeliya Korneva

2008-01-01

131

Carbon offsetting: sustaining consumption?  

Microsoft Academic Search

In this paper we examine how theories of sustainable and ethical consumption help us to understand a new, rapidly expanding type of consumer product designed to mitigate climate change: carbon offsets. The voluntary carbon offset market grew by 200% between 2005 and 2006, and there are now over 150 retailers of voluntary carbon offsets worldwide. Our analysis concentrates on the

Heather Lovell; Harriet Bulkeley; Diana Liverman

2009-01-01

132

Carbon Dioxide Reduction System.  

National Technical Information Service (NTIS)

An automatically operated carbon dioxide reduction system was developed, fabricated and tested. The system was designed to reduce the carbon dioxide equivalent to that produced by one man, and to produce carbon and oxygen. A system such as this is require...

H. Chandler

1964-01-01

133

Carbon Nanotube Image Gallery  

NSDL National Science Digital Library

The mission of NanoLab, Inc. is to utilize nanoscale science and engineering to create high value products from carbon nanotubes, aligned carbon nanotube arrays, and other nanomaterials. This website provides an image gallery of: carbon nanotubes, nanoparticles, nanowire, as well as nanotube fillings, coatings, and arrays.

2011-06-03

134

Screen for Carbon Dioxide.  

ERIC Educational Resources Information Center

|Presents a set of laboratory experiments that can assist students in the detection of carbon dioxide. Offers a variation of the supported drop method of carbon dioxide detection that provides readily visible positive results. Includes background information on carbon dioxide. (ML)|

Foster, John; And Others

1986-01-01

135

Yttrium Acetate-Derived Particle Coatings for Mitigating Oxidation and Corrosion of Inconel 625  

Microsoft Academic Search

Sol paint that yields yttrium-based compounds was prepared by mixing four chemical ingredients, yttrium acetate tetrahydrate precursor, diethanolamine, isopropyl alcohol, and hydrochloric acid, and then applied as oxidation\\/corrosion resistant coatings for Inconel 625 substrates. Annealing the coatings at 500C developed a coalescent microstructure of coarse particles consisting of amorphous yttrium carbonate as the major component and crystalline yttrium oxide (Y2O3)

T. Sugama

1998-01-01

136

Aspects of carbon dioxide utilization  

Microsoft Academic Search

Carbon dioxide reacts with hydrogen, alcohols, acetals, epoxides, amines, carboncarbon unsaturated compounds, etc. in supercritical carbon dioxide or in other solvents in the presence of metal compounds as catalysts. The products of these reactions are formic acid, formic acid esters, formamides, methanol, dimethyl carbonate, alkylene carbonates, carbamic acid esters, lactones, carboxylic acids, polycarbonate (bisphenol-based engineering polymer), aliphatic polycarbonates, etc. Especially,

Iwao Omae

2006-01-01

137

Mass spectroscopic and ESR characterization of soluble yttrium-containing metallofullerenes YC and YC  

Microsoft Academic Search

Solvent soluble, yttrium-containing fullerenes are extracted from yttrium\\/carbon soot produced by the carbon-arc fullerene generation method. An yttrium-graphite composite yields solvent extractable molecules such as YC and YC as evidenced by a laser desorption time-of-flight (LD-TOF) mass spectroscopic analysis of the extracts. This is consistent with the very recent results by Smalley et al. where YC and YC are prepared

Hisanori Shinohara; Hiroyasu Sato; Yahachi Saito; Masato Ohkohchi; Yoshinori Ando

1992-01-01

138

Carbon in detonations  

SciTech Connect

We review three principal results from a five year study of carbon and its properties in detonations and discuss the implications of these results to the behavior of explosives. We first present a new determination of the carbon melt line from release wave velocity measurements in the shocked state. We then outline a colloidal theory of carbon clustering which from diffusion limited coagulation predicts a slow energy release rate for the carbon chemistry. Finally, we show the results from the examination of recovered soot. Here we see support for the colloid theory and find the diamond phase of carbon. The main theme of this paper is that the carbon in detonation products is in the form of a colloidal suspension of carbon clusters which grow through diffusion limited collisions. Even the final state is not bulk graphite or diamond, but is a collection of small, less than 100 /angstrom/A, diamond and graphitic clusters. 23 refs., 4 figs.

Johnson, J.D.

1989-01-01

139

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

140

Soil carbon: Microbes and global carbon  

NASA Astrophysics Data System (ADS)

The amount of organic material that microbes assimilate into their biomass is critical in regulating whether soils, the planet's main pool of organic matter, will absorb or emit carbon in a warmer world.

Schimel, Joshua

2013-10-01

141

Carbon-carbon - heat means strength  

Microsoft Academic Search

Carbon-carbon (C\\/C) composite processing methods and material characteristics are discussed. C\\/C composites, with a combination of properties including high temperature tolerance, dimensional stability, high stiffness and strength, and property retention at elevated temperatures, have application to the conditions encountered at orbital velocities and during atmospheric reentry. C\\/C composite properties can be altered through varying the reinforcement orientation, processing conditions, and

Brahney

1987-01-01

142

Molten carbonate fuel cell separator  

NASA Astrophysics Data System (ADS)

In a stacked array of molten carbonate fuel cells, a fuel cell separator is positioned between adjacent fuel cells to provide isolation as well as a conductive path therebetween. The center portion of the fuel cell separator includes a generally rectangular, flat, electrical conductor. Around the periphery of the flat portion of the separator are positioned a plurality of elongated resilient flanges which form a gas tight seal around the edges of the fuel cell. With one elongated flange resiliently engaging a respective edge of the center portion of the separator, the sealing flanges, which are preferably comprised of a noncorrosive material such as an alloy of yttrium, iron, aluminum or chromium, form a tight fitting wet seal for confining the corrosive elements of the fuel cell therein. This arrangement permits a good conductive material which may be highly subject to corrosion and dissolution to be used in combination with a corrosion resistant material in the fuel cell separator of a molten carbonate fuel cell for improved fuel cell conductivity and a gas tight wet seal.

Nickols, R. C.

1984-10-01

143

Molten carbonate fuel cell separator  

DOEpatents

In a stacked array of molten carbonate fuel cells, a fuel cell separator is positioned between adjacent fuel cells to provide isolation as well as a conductive path therebetween. The center portion of the fuel cell separator includes a generally rectangular, flat, electrical conductor. Around the periphery of the flat portion of the separator are positioned a plurality of elongated resilient flanges which form a gas-tight seal around the edges of the fuel cell. With one elongated flange resiliently engaging a respective edge of the center portion of the separator, the sealing flanges, which are preferably comprised of a noncorrosive material such as an alloy of yttrium, iron, aluminum or chromium, form a tight-fitting wet seal for confining the corrosive elements of the fuel cell therein. This arrangement permits a good conductive material which may be highly subject to corrosion and dissolution to be used in combination with a corrosion-resistant material in the fuel cell separator of a molten carbonate fuel cell for improved fuel cell conductivity and a gas-tight wet seal.

Nickols, Richard C. (East Hartford, CT)

1986-09-02

144

Molten carbonate fuel cell separator  

DOEpatents

In a stacked array of molten carbonate fuel cells, a fuel cell separator is positioned between adjacent fuel cells to provide isolation as well as a conductive path therebetween. The center portion of the fuel cell separator includes a generally rectangular, flat, electrical conductor. Around the periphery of the flat portion of the separator are positioned a plurality of elongated resilient flanges which form a gas-tight seal around the edges of the fuel cell. With one elongated flange resiliently engaging a respective edge of the center portion of the separator, the sealing flanges, which are preferably comprised of a noncorrosive material such as an alloy of yttrium, iron, aluminum or chromium, form a tight-fitting wet seal for confining the corrosive elements of the fuel cell therein. This arrangement permits a good conductive material which may be highly subject to corrosion and dissolution to be used in combination with a corrosion-resistant material in the fuel cell separator of a molten carbonate fuel cell for improved fuel cell conductivity and a gas-tight wet seal.

Nickols, R.C.

1984-10-17

145

The Growth and Characterization of Germanium-Carbon Alloy Thin Films and Solid Phase Equilibria for Metal-Silicon - Ternary Systems: Magnesium, Calcium, Strontium, Barium, Scandium, Yttrium, Lanthanum, Titanium, Zirconium and Hafnium  

Microsoft Academic Search

Thin films of pure germanium-carbon alloys (Ge _{rm x}C _{rm 1-x} with 0 <=q x <=q 1) have been grown on Si and Al_2O_3 substrates by pulsed laser ablation in a high vacuum chamber. The films were analyzed by x-ray 0-20 diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), conductivity measurements and optical absorption spectroscopy. The analyses of

Haojie Yuan

1992-01-01

146

Mesoporous carbon materials  

DOEpatents

The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

Dai, Sheng (Knoxville, TN); Wang, Xiqing (Oak Ridge, TN)

2012-02-14

147

Mesoporous carbon materials  

DOEpatents

The invention is directed to a method for fabricating a mesoporous carbon material, the method comprising subjecting a precursor composition to a curing step followed by a carbonization step, the precursor composition comprising: (i) a templating component comprised of a block copolymer, (ii) a phenolic compound or material, (iii) a crosslinkable aldehyde component, and (iv) at least 0.5 M concentration of a strong acid having a pKa of or less than -2, wherein said carbonization step comprises heating the precursor composition at a carbonizing temperature for sufficient time to convert the precursor composition to a mesoporous carbon material. The invention is also directed to a mesoporous carbon material having an improved thermal stability, preferably produced according to the above method.

Dai, Sheng; Wang, Xiqing

2013-08-20

148

Carbon nanofibers and carbon nanotubes in regenerative medicine  

Microsoft Academic Search

Carbon nanotubes and carbon nanofibers have long been investigated for applications in composite structural materials, semiconductor devices, and sensors. With the recent well-documented ability to chemically modify nanofibrous carbon materials to improve their solubility and biocompatibility properties: a whole new class of bioactive carbon nanostructures has been created for biological applications. This review focuses on the latest applications of carbon

Phong A. Tran; Lijie Zhang; Thomas J. Webster

2009-01-01

149

Land plants, carbon isotopes and the late Paleozoic carbon cycle  

Microsoft Academic Search

Two parameters determine the carbon isotopic composition of plant tissue: the carbon isotopic composition of atmospheric carbon dioxide and the carbon isotopic fractionation associated with plant metabolism. Based on a systematic survey of terrestrial organic matter, we present a carbon isotope record for the late Paleozoic. Investigations directed towards sample type, maturity and host lithology indicate that near primary isotopic

W. Peters-Kottig; H. Strauss; H. Kerp

2003-01-01

150

Carbon nanotube\\/carbon fiber hybrid multiscale composites  

Microsoft Academic Search

Carbon nanotubes were grown directly on carbon fibers using chemical vapor deposition. When embedded in a polymer matrix, the change in length scale of carbon nanotubes relative to carbon fibers results in a multiscale composite, where individual carbon fibers are surrounded by a sheath of nanocomposite reinforcement. Single-fiber composites were fabricated to examine the influence of local nanotube reinforcement on

E. T. Thostenson; W. Z. Li; D. Z. Wang; Z. F. Ren; T. W. Chou

2002-01-01

151

Fiber Strength Utilization in Carbon/Carbon Composites.  

National Technical Information Service (NTIS)

The utilization of tensile strength of carbon fibers in unidirectional carbon/carbon (C/C) composites was studied for a series of four mesophase-pitch-based carbon fibers in a carbon matrix derived from a polyarylacetylene (PAA) resin. The fibers had modu...

R. J. Zaldivar G. S. Rellick J. M. Yang

1993-01-01

152

Some Observations on Stress Graphitization in Carbon-Carbon Composites.  

National Technical Information Service (NTIS)

The in situ stress graphitization behavior of hard carbons in unidirectionally aligned carbon-carbon (C/C) composites was studied for three carbon fibers (PAN-based T-50, pitch-based PX7, and rayon-based WCA) and two carbon precursor resins (phenol-formal...

R. J. Zaldivar G. S. Rellick

1992-01-01

153

Photoconductivity of carbon aerogels  

Microsoft Academic Search

Photoconductivity was measured on a series of carbon aerogels to investigate their electronic properties. Carbon aerogels are a special class of low-density microcellular foams, consisting of interconnected carbon particles ([similar to]120 A diameter) and narrow graphitic ribbons ([similar to]25 A width) intertwined within each particle. Both the dark- and photo-conductivities show drastic changes in the temperature range 5--300 K, which

M. Hosoya; G. Reynolds; M. S. Dresselhaus; P. W. Pekala

1993-01-01

154

Carbon Sequestration Monitoring Activities  

Microsoft Academic Search

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are

Carol Frost

2010-01-01

155

Carbon Nanotube Biosensors  

Microsoft Academic Search

Owing to their nano-dimensions, rich electronic states, large surface area, high mechanical strength, and excellent chemical\\u000a and thermal stability, carbon nanotubes have attracted a great deal of interest [1]. Among the many potential applications [1, 2], carbon nanotubes have recently become promising functional materials for the development of advanced biosensors with novel\\u000a features. It has been demonstrated that carbon nanotubes

Pingang He; Liming Dai

156

Carbon Capture and Storage  

Microsoft Academic Search

Carbon capture and sequestration (CCS) is the long-term isolation of carbon dioxide from the atmosphere through physical, chemical, biological, or engineered processes. This includes a range of approaches including soil carbon sequestration (e.g., through no-till farming), terrestrial biomass sequestration (e.g., through planting forests), direct ocean injection of CO either onto the deep seafloor or into the intermediate depths, injection into

Friedmann

2007-01-01

157

Activated carbon material  

DOEpatents

Activated carbon particles for use as iodine trapping material are impregnated with a mixture of selected iodine and potassium compounds to improve the iodine retention properties of the carbon. The I/K ratio is maintained at less than about 1 and the pH is maintained at above about 8.0. The iodine retention of activated carbon previously treated with or coimpregnated with triethylenediamine can also be improved by this technique. Suitable flame retardants can be added to raise the ignition temperature of the carbon to acceptable standards.

Evans, A. Gary (North Augusta, SC)

1978-01-01

158

Temperature VS Carbon Dioxide  

NSDL National Science Digital Library

In this activity, students examine the relationship between carbon dioxide levels and global temperature change by studying a graph of these two variables. They will discover that by using data from ice cores, scientists can determine temperature and carbon dioxide levels in the air as far back as a hundred thousand years in the past. The students try to predict which variable is the independent one and then make a graph of temperature change and carbon dioxide levels. After making their graph, students describe the relationship between temperature and carbon dioxide levels in the atmosphere to determine if their predictions were correct.

159

Wildland Soil Carbon Management  

NASA Astrophysics Data System (ADS)

In the era of climate change, traditional wildland management practices have come into question, especially with respect to their impact on soil carbon sequestration. Over half of the land area of the United States and Puerto Rico is either in forest or grassland ecosystems, i.e. 302 million hectares of forested lands and 247 million hectares of grasslands and pasture lands. Forested lands hold approximately 35.5 Pg of soil carbon to a depth of 100cm. Private grasslands hold approximately 21 Pg of soil carbon to a depth of 200cm. The difficulty of managing for carbon sequestration becomes more evident when one surveys the variety of complex ecosystems being managed. This presentation highlights implications for wildland management for promoting soil carbon sequestration for sustaining forest and grassland ecosystems in the United States. We will address key considerations, strategies, and opportunities to incorporate soil carbon management into wildland management. Examples of vegetation management influence on soil carbon will be discussed including fire, soil amendments and best management practices for maintaining and/or improving soil carbon sequestration. The USDA Forest Service has established a soil management policy that seeks to conserve soil quality and protect soil carbon on National Forest System lands. Aspects of this national policy will also be presented.

Davis, R. L.; Swanston, C.

2009-12-01

160

Calcium carbonate overdose  

MedlinePLUS

Tums overdose; Calcium overdose ... Calcium ... Products containing calcium carbonate, including Certain antacids (Tums, Chooz) Certain mineral supplements Certain hand lotions Certain vitamin and mineral supplements Note: ...

161

Randomly oriented carbon/carbon composite  

NASA Astrophysics Data System (ADS)

The main objective of this study is to develop an alternate, rapid and cost effective process for the fabrication of carbon/carbon (C/C) composite. Slurry moulding technique is adopted for the fabrication of C/C composite. Randomly oriented hybrid discrete carbon fiber (CF) reinforced and mesophase pitch (MP) derived matrix C/C composite is fabricated. Process parameters are optimized and repeatability is proved. The electrical conductivity of the composite fabricated through the developed process is found to be better than that fabricated through conventional processes. The other properties are also found to be competent. The randomly oriented C/C composite because of its mouldability is found suitable for various applications which require complex shapes.

Raunija, Thakur Sudesh Kumar; Babu, S.

2013-06-01

162

Microbially mediated mineral carbonation  

NASA Astrophysics Data System (ADS)

Mineral carbonation involves silicate dissolution and carbonate precipitation, which are both natural processes that microorganisms are able to mediate in near surface environments (Ferris et al., 1994; Eq. 1). (Ca,Mg)SiO3 + 2H2CO3 + H2O ? (Ca,Mg)CO3 + H2O + H4SiO4 + O2 (1) Cyanobacteria are photoautotrophs with cell surface characteristics and metabolic processes involving inorganic carbon that can induce carbonate precipitation. This occurs partly by concentrating cations within their net-negative cell envelope and through the alkalinization of their microenvironment (Thompson & Ferris, 1990). Regions with mafic and ultramafic bedrock, such as near Atlin, British Columbia, Canada, represent the best potential sources of feedstocks for mineral carbonation. The hydromagnesite playas near Atlin are a natural biogeochemical model for the carbonation of magnesium silicate minerals (Power et al., 2009). Field-based studies at Atlin and corroborating laboratory experiments demonstrate the ability of a microbial consortium dominated by filamentous cyanobacteria to induce the precipitation of carbonate minerals. Phototrophic microbes, such as cyanobacteria, have been proposed as a means for producing biodiesel and other value added products because of their efficiency as solar collectors and low requirement for valuable, cultivable land in comparison to crops (Dismukes et al., 2008). Carbonate precipitation and biomass production could be facilitated using specifically designed ponds to collect waters rich in dissolved cations (e.g., Mg2+ and Ca2+), which would allow for evapoconcentration and provide an appropriate environment for growth of cyanobacteria. Microbially mediated carbonate precipitation does not require large quantities of energy or chemicals needed for industrial systems that have been proposed for rapid carbon capture and storage via mineral carbonation (e.g., Lackner et al., 1995). Therefore, this biogeochemical approach may represent a readily implemented and economically efficient alternative to other technologies currently under development for mineral sequestration. Dismukes GC, Carrieri D, Bennette N, Ananyev GM, Posewitz MC (2008) Aquatic phototrophs: efficient alternatives to land-based crops for biofuels. Current Opinion in Biotechnology, 19, 235-240. Ferris FG, Wiese RG, Fyfe WS (1994) Precipitation of carbonate minerals by microorganisms: Implications of silicate weathering and the global carbon dioxide budget. Geomicrobiology Journal, 12, 1-13. Lackner KS, Wendt CH, Butt DP, Joyce EL, Jr., Sharp DH (1995) Carbon dioxide disposal in carbonate minerals. Energy, 20, 1153-1170. Power IM, Wilson SA, Thom JM, Dipple GM, Gabites JE, Southam G (2009) The hydromagnesite playas of Atlin, British Columbia, Canada: A biogeochemical model for CO2 sequestration. Chemical Geology, 206, 302-316. Thompson JB, Ferris FG (1990) Cyanobacterial precipitation of gypsum, calcite, and magnesite from natural alkaline lake water. Geology, 18, 995-998.

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

2010-12-01

163

Carbon dioxide foam flooding  

Microsoft Academic Search

A method of conducting an enhanced oil recovery process in a subterranean reservoir is described. There is injected into the reservoir as a sweep fluid a foam containing carbon dioxide, water, and a foaming agent having the formula ROCOCHSOOM, where R is a straight chain alkyl radical having from 10 to 16 carbon atoms, and M is an alkali metal

P. W. Fischer; L. W. Holm; D. S. Pye

1978-01-01

164

Carbon nanotube polymer composites  

Microsoft Academic Search

The state of research into carbon nanotube\\/polymermatrix composites for mechanical reinforcement is critically reviewed with emphasis on recent advances in CNT composite toughness. Particular interest is also given to interfacial bonding of carbon nanotubes to polymer matrices as it applies to stress transfer from the matrix to the CNT. Potential topics of oncoming focus are highlighted.

R. Andrews; M. C. Weisenberger

2004-01-01

165

Production of Carbon Dioxide  

NSDL National Science Digital Library

In this chemistry activity, learners use common chemicals to produce carbon dioxide and observe its properties. This resource includes brief questions for learners to answer after the experiment. Use this activity to introduce learners to carbon dioxide and its use as a fire extinguisher. Note: this activity involves an open flame.

House, The S.

2013-05-15

166

Carbon Dioxide and Climate.  

ERIC Educational Resources Information Center

The amount of carbon dioxide in the atmosphere is increasing at a rate that could cause significant warming of the Earth's climate in the not too distant future. Oceanographers are studying the role of the ocean as a source of carbon dioxide and as a sink for the gas. (Author/BB)

Brewer, Peter G.

1978-01-01

167

Material Science of Carbon.  

National Technical Information Service (NTIS)

Carbon is a ubiquitous material that is essential for the functioning of modern society. Because carbon can exist in a multitude of forms, it can be tailored to possess practically any property that might be required for a specific application. The list o...

W. Hoffman

2004-01-01

168

Carbon Dioxide Removal  

NSDL National Science Digital Library

In this experiment using sprigs of Elodea, learners will observe a natural process that removes carbon dioxide (CO2) from Earth's atmosphere. This process is a part of the carbon cycle and results in temperature suitable for life. Note: this experiment requires that learners make observations an hour or the next day after they set up the materials.

History, American M.

2008-01-01

169

Carbon sequestration by switchgrass  

Microsoft Academic Search

Increasing levels of carbon dioxide (CO2), which is partly due to use of fossil fuel, is primarily responsible for global climate warming. Producing and using switchgrass for bioenergy can help reduce atmospheric CO2 buildup by partly replacing use of fossil fuels and by carbon (C) sequestration. Switchgrass (Panicum virgatum L) is a potential bioenergy crop suited to the southeastern U.S.

Zhiqin Ma

1999-01-01

170

Lead carbonate scintillator materials  

DOEpatents

Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

Derenzo, Stephen E. (Pinole, CA); Moses, William W. (Berkeley, CA)

1991-01-01

171

Carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

Carbon nanotube arrays were prepared by chemical vapor deposition (CVD) of hydrocarbon gas on various substrates. The effect of substrates on the growth, morphology and structure of carbon nanotubes were investigated. Aligned carbon nanotubes with high density and purity were achieved by CVD on bulk silica substrate. On the film-like substrates, very long carbon nanotubes of length 2 mm were produced, which is an order of magnitude longer (1 mm vs. 100 ?m) than that described in most previous reports. High-resolution transmission electron microscopy (HRTEM) investigation illustrates that these carbon nanotubes are well graphitized and very pure. The tubes are typically consist of several to tens of concentric shells of carbon sheets with spacing about 0.34 nm. Micro-Raman spectroscopy has been carried out to detect the microstructures of CNT. The observed ratio of the integrated intensity of D and G band was found different from that of carbon nanotubes produced by arc-discharge method and pyrolytic graphite (PG). The resonance properties and higher order Raman bands are also different from other forms of carbon. With the help of the results of SEM and HRTEM the origination of the broader band structure were discussed.

Xie, S. S.; Li, W. Z.; Pan, Z. W.; Chang, B. H.; Sun, L. F.

172

Carbon nanotubes for nanorobotics  

Microsoft Academic Search

The well-defined geometry, exceptional mechanical properties, and extraordinary electrical characteristics of carbon nanotubes qualify them for structuring nanoelectronic circuits, nanoelectromechanical systems, and nanorobotic systems. Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes can be used as robust nanoscale motion enabling mechanisms for applications such as bearings, switches, gigahertz oscillators, shuttles, memories, syringes, and actuators. The hollow

Lixin Dong; Arunkumar Subramanian; Bradley J. Nelson

2007-01-01

173

Carbon Nanotube templated structures  

Microsoft Academic Search

Carbon nano tubes are of great interest to science due to their strong mechanical and exotic electrical properties. Nano tubes have potential application in transistors, micro electrical mechanical devices (MEMS), and structural materials. We have been using nanotube forests as a template to fabricate larger scale structures. The nanotube template is infiltrated with another material (like silicon or carbon). This

Ricky Wyman; Robert Davis; Richard Vanfleet; Jun Song

2009-01-01

174

Carbon capture and storage  

Microsoft Academic Search

Carbon capture and storage (CCS) covers a broad range of technologies that are being developed to allow carbon dioxide (CO2) emissions from fossil fuel use at large point sources to be transported to safe geological storage, rather than being emitted to the atmosphere. Some key enabling contributions from technology development that could help to facilitate the widespread commercial deployment of

Jon Gibbins; Hannah Chalmers

2008-01-01

175

Seeing the Carbon Cycle  

ERIC Educational Resources Information Center

|In this article, the authors present a classroom experiment that was developed to introduce middle school learners to the carbon cycle. The experiment deals with transfer of CO[subscript 2] between liquid reservoirs and the effect CO[subscript 2] has on algae growth. It allows students to observe the influence of the carbon cycle on algae growth,

Drouin, Pamela; Welty, David J.; Repeta, Daniel; Engle-Belknap, Cheryl A.; Cramer, Catherine; Frashure, Kim; Chen, Robert

2006-01-01

176

Carbon Dioxide Fountain  

ERIC Educational Resources Information Center

|This article presents the development of a carbon dioxide fountain. The advantages of the carbon dioxide fountain are that it is odorless and uses consumer chemicals. This experiment also is a nice visual experiment that allows students to see evidence of a gaseous reagent being consumed when a pressure sensor is available. (Contains 3 figures.)

Kang, Seong-Joo; Ryu, Eun-Hee

2007-01-01

177

Ingredients for Life: Carbon  

NSDL National Science Digital Library

Carbon is the basis of all organic molecules. It is also one of the most abundant elements in the universe. This video segment illustrates the special characteristics of carbon that make it an essential ingredient for life. The segment is one minute thirty-eight seconds in length. A background essay and list of discussion questions are also provided.

178

Monitoring Global Ocean Carbon Inventories.  

National Technical Information Service (NTIS)

Contents: Foreword by OOSDP chairman; Preface by Author; Significance of a Changing Oceanic Carbon Inventory; The Case for Monitoring Ocean Carbon Inventories; Ocean Carbon Monitoring Approaches (Air-Sea Fluxes, CO(sub 2) Transport within the Ocean, Inven...

D. W. R. Wallace

1995-01-01

179

Isolation of Carbon Nanostructures  

SciTech Connect

Carbon nanostructures such a single wall carbon nanotubes (SWCNT), double wall carbon nanotubes (DWCNT) and fullerene peapods (e.g. C70 at SWCNT) usually occur in the form of bundles. Here, we present application of a novel simple and versatile method for deposition of small isolated nanoribbons of carbon nanotubes on annealed gold surface. The nanoribbons were characterized by Raman spectroscopy and exhibit characteristic features of individual carbon nanostructures. The resonance condition allowed the observation of a distinct spectrum of one inner tube in the nanoribbon from DWCNT. The signal of inner tubes of isolated DWCNT nanoribbons was found to be up to 50 times stronger than the sum of signals of the corresponding tubes in buckypaper sample. This dramatic enhancement is assigned to SERS (surface enhanced resonant Raman scattering) effect.

Kalbac, Martin; Kavan, Ladislav [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-182 23 Prague 8 (Czech Republic); Leibniz Institute of Solid State and Materials Research, Helmholtzstr. 20, D - 01069 Dresden (Germany); Pelouchova, Hana; Janda, Pavel; Zukalova, Marketa [J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-182 23 Prague 8 (Czech Republic); Dunsch, Lothar [Leibniz Institute of Solid State and Materials Research, Helmholtzstr. 20, D - 01069 Dresden (Germany)

2005-09-27

180

Carboxysomal carbonic anhydrases.  

PubMed

Cyanobacteria and some chemoautotrophic bacteria enhance their carbon fixation efficiency by actively concentrating bicarbonate within their cytosol. However, converting bicarbonate into carbon dioxide - the form required by RubisCO - would result in its rapid escape through cellular membranes. These organisms resolve this dilemma by sequestering RubisCO behind a semi-permeable protein shell; the resulting large insoluble bodies are known as carboxysomes. For the carbon concentrating mechanism to function, there is an absolute requirement for carbonic anhydrase activity within the carboxysome to convert the bicarbonate to cabon dioxide, and a simultaneous requirement that minimal carbonic anhydrase activity be found within the cystol. Carboxysomal carbomic anhydrases therefore contain additional motifs and domains that generally mediate protein-protein interactions, or encapsulation dependent activation mechanisms. Carboxysomes are found in two deeply divergent varieties. Alpha-Carboxysomes contain a ?-carbonic anhydrase, CsoSCA, which is so divergent from canonical ?-carbonic anhydrases that it was originally thought to be the founding member of a new class. Beta carboxysomes have CcmM whose N-terminal domain is an active ?-carbonic ahydrase in some strains, but in others has lost all activity and functions primarily as a protein complex assembly scaffold; in addition, a subset of ?-carboxysomes also contain the ?-carbonic anhydrase CcaA - either in addition to, or instead of, an active CcmM. Here we explore the structures, activities and interactions mediated by the three known carboxysomal carbonic anhydrases, and discuss the mechanisms by which they are recruited to the carboxysome. PMID:24146376

Kimber, Matthew S

2014-01-01

181

Carbon copy deaths: Carbon monoxide gas chamber  

Microsoft Academic Search

The news media can exert a powerful influence over suicidal behaviour. It has been observed that like-minded individuals are able to preplan a group suicide method using modern communication technology in the form of websites and online chatrooms and mobile phone texting.A case of carbon monoxide (CO) poisoning is presented to illustrate the recent phenomenon of cyber suicides by suffocation

F. Patel

2008-01-01

182

Prokaryotic carbonic anhydrases.  

PubMed

Carbonic anhydrases catalyze the reversible hydration of CO(2) [CO(2)+H(2)Oright harpoon over left harpoon HCO(3)(-)+H(+)]. Since the discovery of this zinc (Zn) metalloenzyme in erythrocytes over 65 years ago, carbonic anhydrase has not only been found in virtually all mammalian tissues but is also abundant in plants and green unicellular algae. The enzyme is important to many eukaryotic physiological processes such as respiration, CO(2) transport and photosynthesis. Although ubiquitous in highly evolved organisms from the Eukarya domain, the enzyme has received scant attention in prokaryotes from the Bacteria and Archaea domains and has been purified from only five species since it was first identified in Neisseria sicca in 1963. Recent work has shown that carbonic anhydrase is widespread in metabolically diverse species from both the Archaea and Bacteria domains indicating that the enzyme has a more extensive and fundamental role in prokaryotic biology than previously recognized. A remarkable feature of carbonic anhydrase is the existence of three distinct classes (designated alpha, beta and gamma) that have no significant sequence identity and were invented independently. Thus, the carbonic anhydrase classes are excellent examples of convergent evolution of catalytic function. Genes encoding enzymes from all three classes have been identified in the prokaryotes with the beta and gamma classes predominating. All of the mammalian isozymes (including the 10 human isozymes) belong to the alpha class; however, only nine alpha class carbonic anhydrase genes have thus far been found in the Bacteria domain and none in the Archaea domain. The beta class is comprised of enzymes from the chloroplasts of both monocotyledonous and dicotyledonous plants as well as enzymes from phylogenetically diverse species from the Archaea and Bacteria domains. The only gamma class carbonic anhydrase that has thus far been isolated and characterized is from the methanoarchaeon Methanosarcina thermophila. Interestingly, many prokaryotes contain carbonic anhydrase genes from more than one class; some even contain genes from all three known classes. In addition, some prokaryotes contain multiple genes encoding carbonic anhydrases from the same class. The presence of multiple carbonic anhydrase genes within a species underscores the importance of this enzyme in prokaryotic physiology; however, the role(s) of this enzyme is still largely unknown. Even though most of the information known about the function(s) of carbonic anhydrase primarily relates to its role in cyanobacterial CO(2) fixation, the prokaryotic enzyme has also been shown to function in cyanate degradation and the survival of intracellular pathogens within their host. Investigations into prokaryotic carbonic anhydrase have already led to the identification of a new class (gamma) and future research will undoubtedly reveal novel functions for carbonic anhydrase in prokaryotes. PMID:10978542

Smith, K S; Ferry, J G

2000-10-01

183

Preparation of PAN\\/phenolic-based carbon\\/carbon composites with flexible towpreg carbon fiber  

Microsoft Academic Search

Carbon\\/carbon composites made with flexible towpreg carbon fiber as reinforcement and phenolic resins as matrix precursor were impregnated with pitch during re-carbonization process. The structural characteristics of the composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), three-point bending tests, Archimedes method and water adsorption. Results showed that the density of the carbon\\/carbon composites increases from 1.45 to

Wei Li; Zhenhua Chen; Jin Li; Xianhong Chen; Hao Xuan; Xiaoyi Wang

2008-01-01

184

Carbon monoxide poisoning (acute)  

PubMed Central

Introduction Carbon monoxide is an odourless, colourless gas, and poisoning causes hypoxia, cell damage, and death. Exposure to carbon monoxide is measured either directly from blood samples and expressed as a percentage of carboxyhaemoglobin, or indirectly using the carbon monoxide in expired breath. Carboxyhaemoglobin percentage is the most frequently used biomarker of carbon monoxide exposure. Although the diagnosis of carbon monoxide poisoning can be confirmed by detecting elevated levels of carboxyhaemoglobin in the blood, the presence of clinical signs and symptoms after known exposure to carbon monoxide should not be ignored. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of oxygen treatments for acute carbon monoxide poisoning? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 12 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: 100% hyperbaric oxygen, oxygen 28%, and oxygen 100% by non-re-breather mask.

2010-01-01

185

Small diameter carbon nanopipettes  

NASA Astrophysics Data System (ADS)

Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

2010-01-01

186

Small diameter carbon nanopipettes.  

PubMed

Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 degrees C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 degrees C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca(2+) signals, fast recovery of basal Ca(2+) levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h. PMID:19946151

Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

2009-11-30

187

IMPACCT: Carbon Capture Technology  

SciTech Connect

IMPACCT Project: IMPACCTs 15 projects seek to develop technologies for existing coal-fired power plants that will lower the cost of carbon capture. Short for Innovative Materials and Processes for Advanced Carbon Capture Technologies, the IMPACCT Project is geared toward minimizing the cost of removing carbon dioxide (CO2) from coal-fired power plant exhaust by developing materials and processes that have never before been considered for this application. Retrofitting coal-fired power plants to capture the CO2 they produce would enable greenhouse gas reductions without forcing these plants to close, shifting away from the inexpensive and abundant U.S. coal supply.

None

2012-01-01

188

Improving carbon fixation pathways.  

PubMed

A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that novel pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials. PMID:22647231

Ducat, Daniel C; Silver, Pamela A

2012-05-29

189

Improving Carbon Fixation Pathways  

PubMed Central

A recent resurgence in basic and applied research on photosynthesis has been driven in part by recognition that fulfilling future food and energy requirements will necessitate improvements in crop carbon-fixation efficiencies. Photosynthesis in traditional terrestrial crops is being reexamined in light of molecular strategies employed by photosynthetic microbes to enhance the activity of the Calvin cycle. Synthetic biology is well-situated to provide original approaches for compartmentalizing and enhancing photosynthetic reactions in a species independent manner. Furthermore, the elucidation of alternative carbon-fixation routes distinct from the Calvin cycle raises possibilities that alternative pathways and organisms can be utilized to fix atmospheric carbon dioxide into useful materials.

Ducat, Daniel C.

2012-01-01

190

Carbon footprint calculator  

NSDL National Science Digital Library

This site is produced by British Petroleum and provides a simple, interactive guide to estimate your annual household carbon emissions. The calculator asks questions about the features of your residence, car travel, air travel and recycling habits. As each question is answered, a graph displays the carbon emissions so you can see the effects of each of the options presented. This tool is intended as an approximate guide only, but is useful for stimulating an awareness of the approximate amount of carbon dioxide emitted by everyday tasks.

Petroleum, British

191

Preparing to capture carbon  

SciTech Connect

Carbon sequestration from large sources of fossil fuel combustion, particularly coal, is an essential component of any serious plan to avoid catastrophic impacts of human-induced climate change. Scientific and economic challenges still exist, but none are serious enough to suggest that carbon capture and storage will not work at the scale required to offset trillions of tons of carbon dioxide emissions over the next century. The challenge is whether the technology will be ready when society decides that it is time to get going.

Schrag, D.P. [Harvard University, Cambridge, MA (United States)

2007-02-09

192

Carbon Budget and Carbonate Saturation in Global Paleo-ocean  

Microsoft Academic Search

The relationships between the global carbon cycle and paleo-climates on short and long time scales have been based on studies of accumulation rate of different components of the sedimentary carbon reservoir, as well as reconstructions of the geographic distributions of carbon burial. Variations in the rate and proportion of carbonate burial through Phanerozoic time have been attributed to the influence

R. E. Locklair; A. Lerman

2002-01-01

193

Characteristics of re-inforced Carbon-Carbon  

Microsoft Academic Search

The Reinforced Carbon-Carbon (RCC) is gaining significant position among the materials of modern period. The light weight and high strength composite is finding its way in various applications of Bio, Medical, Space and Defence fields. The growing use of Carbon Fiber Reinforced Carbon (CFRC) composites as high performing material in aerospace and defence industries has prompted studies in developing technology

K. V. Krishnasastry; S. Dhanalakshmi; V. Seshagirirao; K. Palanikumar

2010-01-01

194

In situ nitrogen enriched carbon for carbon dioxide capture  

Microsoft Academic Search

In situ nitrogen enriched carbon was synthesized from locally available low cost soybean as the proteinaceous source. The material was synthesized by chemical activation using zinc chloride followed by physical activation using CO2. The surface area of synthesized nitrogen enriched carbon was found to be 811m2\\/g which is comparable with commercially available activated carbon. The nitrogen enriched carbon was having

Jayshri A. Thote; Kartik S. Iyer; Ravikrishna Chatti; Nitin K. Labhsetwar; Rajesh B. Biniwale; Sadhana S. Rayalu

2010-01-01

195

Authigenic Carbonate and the History of the Global Carbon Cycle  

NASA Astrophysics Data System (ADS)

We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O2 or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic.

Schrag, Daniel P.; Higgins, John. A.; Macdonald, Francis A.; Johnston, David T.

2013-02-01

196

Carbon-carbon - heat means strength  

SciTech Connect

Carbon-carbon (C/C) composite processing methods and material characteristics are discussed. C/C composites, with a combination of properties including high temperature tolerance, dimensional stability, high stiffness and strength, and property retention at elevated temperatures, have application to the conditions encountered at orbital velocities and during atmospheric reentry. C/C composite properties can be altered through varying the reinforcement orientation, processing conditions, and type of matrix and reinforcement. These materials become increasingly stronger up to about 3500 C. The processing of C/C differs from that of most composite structures in the steps of pyrolysis treatment, coating for oxidative protection (using, primarily, ceramics), and impregnation of the outer layer with a silica compound to seal the cracks and pores.

Brahney, J.H.

1987-06-01

197

Carbon Nanotube Filter.  

National Technical Information Service (NTIS)

Monolithic, macroscopic, nanoporous nanotube filters are fabricated having radially aligned carbon nanotube walls. The freestanding filters have diameters and lengths up to several centimeters. A single-step filtering process was demonstrated in two impor...

A. Srivastava O. N. Srivastava P. M. Ajayan R. Vajtal S. Talapatra

2005-01-01

198

Ringed-Carbon Compounds  

NSDL National Science Digital Library

In this interactive activity adapted from NOVA, learn about alkaloids and steroids, both examples of compounds with carbon rings. Short videos with interviews,animations, and photographs are featured.

Foundation, Wgbh E.

2007-02-12

199

Carbon partitioning in photosynthesis.  

PubMed

The work seeks to raise awareness of a fundamental problem that impacts the renewable generation of fuels and chemicals via (photo)synthetic biology. At issue is regulation of the endogenous cellular carbon partitioning between different biosynthetic pathways, over which the living cell exerts stringent control. The regulation of carbon partitioning in photosynthesis is not understood. In plants, microalgae and cyanobacteria, methods need be devised to alter photosynthetic carbon partitioning between the sugar, terpenoid, and fatty acid biosynthetic pathways, to lower the prevalence of sugar biosynthesis and correspondingly upregulate terpenoid and fatty acid hydrocarbons production in the cell. Insight from unusual but naturally occurring carbon-partitioning processes can help in the design of blueprints for improved photosynthetic fuels and chemicals production. PMID:23542013

Melis, Anastasios

2013-03-28

200

Carbon in the Oceans  

NSDL National Science Digital Library

In this assignment, students in small groups are asked to interpret and explain a figure depicting one aspect of marine carbon biogeochemistry. Then a representative of each group explains the figure to the class.

Townsend-Small, Amy

201

Carbon sequestration in soils  

SciTech Connect

The purpose of this article is to examine (a) the magnitude of the potential for carbon sequestration in the soil as a means of reducing carbon dioxide (CO{sub 2}) in the atmosphere, (b) some of the measures that might be used to achieve this potential, (c) the methods available for estimating carbon sequestration on a farm or regional level, (d) what is needed to achieve international consensus, and (e) additional information needs. This article is not presented as a definitive document but rather as an overview of where scientific opinion converges and where more work is needed. In addition, it aims to provoke discussion of the measures that can increase soil carbon sequestration and the policies that might be used to implement those measures.

Bruce, J.P. [Soil and Water Conservation Society, Ottawa, Ontario (Canada); Frome, M. [Soil and Water Conservation Society, Washington, DC (United States); Haites, E. [Margaree Consultants, Toronto, Ontario (Canada); Janzen, H. [Agriculture and Agri-Food Canada, Lethbridge, Alberta (Canada); Lal, R. [Ohio State Univ., Columbus, OH (United States). School of Natural Resources; Paustian, K. [Colorado State Univ., Fort Collins, CO (United States). Natural Resource Ecology Lab.

1999-01-01

202

Carbon monoxide intoxication  

SciTech Connect

Carbon monoxide poisoning usually results from inhalation of exhaust fumes from motor vehicles, smoke from fires or fumes from faulty heating systems. Carbon monoxide has a high affinity for hemoglobin, with which it forms carboxyhemoglobin. The resulting decrease in both oxygen-carrying capacity and oxygen release can lead to end-organ hypoxia. The clinical presentation is nonspecific. Headache, dizziness, fatigue and nausea are common in mild to moderate carbon monoxide poisoning. In more severe cases, tachycardia, tachypnea and central nervous system depression occur. When carbon monoxide intoxication is suspected, empiric treatment with 100 percent oxygen should be initiated immediately. The diagnosis is confirmed by documenting an elevated carboxyhemoglobin level. Hyperbaric oxygen therapy is recommended in patients with neurologic dysfunction, cardiac dysfunction or a history of unconsciousness. 26 refs.

Kales, S.N. (Cambridge Hospital, MA (United States))

1993-11-01

203

Carbonate sequences spark debate  

SciTech Connect

While sequence stratigraphy has become widely accepted and applied in siliciclastic depositional environments around the world, its application to carbonate systems remains somewhat controversial. In the US sequence stratigraphy studies have focused mainly on the siliciclastic-dominated Gulf of Mexico. European explorationists, however, have long been interested in whether sequence stratigraphy concepts are equally valid in carbonate environments. This paper reviews comments by Thierry Jacquin, a French geoscientist at the Universite' de Bourgogne in Dijon. His studies of carbonate outcrops from platform to basement conclude that the stratal patterns of carbonate systems tracts are basically similar to those of siliciclastic system tracts. His primary study was performed on the southern Vercors Plateau, of the northern sub-Alpine chains in France, at the Barremian platform margin.

Not Available

1991-12-01

204

Carbon dioxide (reduction).  

National Technical Information Service (NTIS)

The twin problems of global warming, caused by an increase in atmospheric carbon dioxide (CO2) concentrations, and limited fossil fuel resources have stimulated research in the utilization of CO2. These problems would be partially alleviated by the develo...

A. Fujita

2000-01-01

205

Carbon Monoxide and Pregnancy  

MedlinePLUS

... or falling, chest pain, sleepiness and loss of consciousness. Severe carbon monoxide poisoning can cause death. Can ... mother are high enough to make her lose consciousness. What should I do if Im pregnant ...

206

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The collection of luminescent microorganisms are maintained under cultivation to provide suitable biosensors for the testing program for carbon dioxide. The basic bioluminescent agar medium is currently being used for growth of the cultures. Tests of lumi...

P. S. Biernacki J. J. Kalvinskas

1973-01-01

207

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The program was initiated to establish the feasibility of applying bioluminescent technology for monitoring of carbon dioxide (CO2) in life-support systems for divers, swimmers and underwater habitats. Experiments were performed to obtain bioluminescent c...

P. S. Biernacki J. J. Kalvinskas

1973-01-01

208

Carbon Dioxide Monitoring.  

National Technical Information Service (NTIS)

The program was initiated to establish the feasibility of applying bioluminescent technology for monitoring of carbon dioxide (CO2) in life-support systems for divers, swimmers and underwater habitats. Experiments were performed to obtain bioluminescent c...

P. S. Biernacki J. L. Kalvinskas

1974-01-01

209

Glassy Carbon, Alloys.  

National Technical Information Service (NTIS)

Glassy carbons containing the element iron were prepared by pyrolysis in an inert atmosphere from copolymers of furfuryl alcohol (PFA) and organometallics such as ferrocene dicarboxylic acid (FDA) and vinyl ferrocene (VF) at temperatures from 500C to 970C...

P. L. Walker

1972-01-01

210

Occult Carbon Monoxide Poisoning  

PubMed Central

A syndrome of headache, fatigue, dizziness, paresthesias, chest pain, palpitations and visual disturbances was associated with chronic occult carbon monoxide exposure in 26 patients in a primary care setting. A causal association was supported by finding a source of carbon monoxide in a patient's home, workplace or vehicle; results of screening tests that ruled out other illnesses; an abnormally high carboxyhemoglobin level in 11 of 14 patients tested, and abatement or resolution of symptoms when the source of carbon monoxide was removed. Exposed household pets provided an important clue to the diagnosis in some cases. Recurrent occult carbon monoxide poisoning may be a frequently overlooked cause of persistent or recurrent headache, fatigue, dizziness, paresthesias, abdominal pain, diarrhea and unusual spells.

Kirkpatrick, John N.

1987-01-01

211

Carbon Dioxide Absorption Manifold.  

National Technical Information Service (NTIS)

The device is for removing carbon dioxide from the atmosphere without the attendant release or production of noxious chemicals. It is for use in a submerged submarine. The device includes a housing, inlets, canisters containing lithium hydroxide, a blower...

W. E. McConnaughey

1965-01-01

212

Carbon Monoxide Episodes.  

National Technical Information Service (NTIS)

Carbon Monoxide is commonly thought of as a local pollutant affecting relatively small geographic area. Since most CO emissions result from the operation of motor vehicles; high CO concentrations are associated with the congested areas of large urban cent...

M. Wolcott

1981-01-01

213

[Particle therapy: carbon ions].  

PubMed

Carbon ion therapy is an innovative radiation therapy. It has been first proposed in the forties by Robert Wilson, however the first dedicated centres for human care have been build up only recently in Japan and Germany. The interest of carbon ion is twofold: 1) the very sharp targeting of the tumour with the so called spread out Bragg peak that delivers most of the beam energy in the tumour and nothing beyond it, sparing very efficiently the healthy tissues; 2) the higher relative biological efficiency compared to X rays or protons, able to kill radioresistant tumour cells. Both properties make carbon ions the elective therapy for non resectable radioresistant tumours loco-regionally threatening. The technical and clinical experience accumulated during the recent decades is summarized in this paper along with a detailed presentation of the elective indications. A short comparison between conventional radiotherapy and hadrontherapy is proposed for the indications which are considered as priority for carbon ions. PMID:20659870

Pommier, Pascal; Hu, Yi; Baron, Marie-Hlne; Chapet, Olivier; Balosso, Jacques

2010-07-01

214

Carbon Isotope Ratios in Belowground Carbon Cycle Processes  

Microsoft Academic Search

Abstract Analyses of carbon isotope ratios (?,C values of CO2effluxing from soils, but asof,yet a global,database,is lacking,with which,to test this prediction. Such a global,database,would be a useful input for global carbon cycle models,which,rely on ?values,to constrain source and sink relations. Keywords: global change, ecosystem processes, soil organic carbon, carbon isotope ratio, carbon cycle,

James R. Ehleringer; Nina Buchmann; Lawrence B. Flanagan

2000-01-01

215

Hydrogenated Amorphous Carbon Films  

Microsoft Academic Search

\\u000a Hydrogenated amorphous carbon (a-C:H) thin film is one of the most studied materials due to its unique features. The a-C:H\\u000a thin film is a remarkable material because of its novel optical, mechanical and electrical properties and its similarities\\u000a to diamond. In this chapter we reviewed the structural and optical properties of hydrogenated amorphous carbon (a-C:H) thin\\u000a films prepared in a

Suriani Abu Bakar; Azira Abdul Aziz; Putut Marwoto; Samsudi Sakrani; Mohamad Rusop

216

Material Science of Carbon  

NASA Astrophysics Data System (ADS)

Carbon is a ubiquitous material that is essential for the functioning of modern society. Because carbon can exist in a multitude of forms, it can be tailored to possess practically any property that might be required for a specific application. The list of applications is very extensive and includes: aircraft brakes, electrodes, high temperature molds, rocket nozzles and exit cones, tires, ink, nuclear reactors and fuel particles, filters, prosthetics, batteries and fuel cells, airplanes, and sporting equipment.

Hoffman, Wesley P.

217

Carbon Cycle Poster  

NSDL National Science Digital Library

In this activity, learners gain knowledge about how carbon moves through all four of the Earths major spheres (biosphere, hydrosphere, atmosphere, and lithosphere), and understand how humans influence the carbon cycle and contribute to global climate change. Learners work in groups to create a diagram to show how the Earth's major spheres are connected by diffusion, respiration, burial, and weathering. This detailed lesson plan includes key vocabulary words, discussion questions, resources for educators, and is standards-based.

Sciences, California A.

2008-01-01

218

Sedimentary Rocks: Carbonate Rocks  

NSDL National Science Digital Library

Sedimentary Rocks: Carbonate Rocks is a course handout meant to accompany the discussion of chemical and biochemical sedimentary rocks. Rock composition is broken into the main categories of limestone and dolostone. Depositional conditions are discussed, including the topics of coral reefs, plankton, and carbonate compensation depth (CCD). There are a few photographs, which display calcareous algae. Links are provided to the online Physical Geology resources at Georgia Perimeter College.

Gore, Pamela

219

Prokaryotic carbonic anhydrases  

Microsoft Academic Search

Carbonic anhydrases catalyze the reversible hydration of CO2 [CO2+H2O?HCO3?+H+]. Since the discovery of this zinc (Zn) metalloenzyme in erythrocytes over 65 years ago, carbonic anhydrase has not only been found in virtually all mammalian tissues but is also abundant in plants and green unicellular algae. The enzyme is important to many eukaryotic physiological processes such as respiration, CO2 transport and

Kerry S Smith; James G Ferry

2000-01-01

220

BIOMINERALIZATION FOR CARBON SEQUESTRATION  

Microsoft Academic Search

The objective of this study is to investigate biogeochemical processes utilizing metal-rich fly ash for carbon sequestration and metal immobilization. Metal-reducing bacteria enriched from fly ash ponds and extreme environments were capable of CO2 conversion into sparingly soluble carbonate minerals using metal-rich fly ash and lactate as an energy source in the presence of different atmospheres (80% N2-20% CO2, 80%

T. J. Phelps; Y. Roh

221

Development of carbon-carbon sandwich panels  

NASA Astrophysics Data System (ADS)

The Electrostatic Gravity Gradiometer (EGG) is the main payload of the Gravity field and steady state Ocean Circulation Explorer (GOCE) mission, which has the objectives of producing models of the Earth's gravity field and geoid with high resolution and accuracy. The EGG allows measuring the components of the gravity gradient tensor by means of a set of accelerometers. To meet the outstanding measurement requirements, the EGG structure must provide high dimensional stability under the expected environmental conditions. Carbon-Carbon technology has been selected for the construction of the sandwich panels, which support the accelerometers and their electronics, as well as the thermal control unit. This technology in fact offers good thermo-elastic characteristics, low sensitivity to moisture (only for organic assembly), high panel stiffness-to-mass ratio. Due to the lack of heritage for large-size sandwich structures, a dedicated evaluation and qualification program has been established for the demonstration of the suitability of the sandwich and associated manufacturing processes to the GOCE applications. Following the evaluation of candidate materials and associated bonding techniques, a preferred baseline has been selected that is undergoing qualification testing. A safe two-steps manufacturing process of the sandwich panels has been adopted: C/C face-sheets and honeycomb cores are procured from Hitco Carbon Composites Inc, USA, and their assembly is performed by Alcatel Space through organic bonding, to obtain the final sandwich structure. The results of the evaluation and of the first qualification tests are presented in the paper.

Panin, Fabio; Lutz-Nivet, Martine; Lemaire, Hugues

2003-09-01

222

Nano-Carbons as Theranostics  

PubMed Central

Nano-carbons, including fullerenes, carbon nanoparticles, carbon nanotubes, graphene, and nano-diamonds, are an important class of nanostructures attracting tremendous interests in the past two decades. In this special issue, seven review articles and research reports are collected, to summarize and present the latest progress in the exploration of various nano-carbons for theranostic applications.

Liu, Zhuang; Liang, Xing-Jie

2012-01-01

223

Carbon monoxide production by algae  

Microsoft Academic Search

Carbon monoxide production has been demonstrated in Egregia menzies, several other algae and in the higher plants, Zostera marina and Medicago saliva. The ability to produce carbon monoxide is not destroyed by heating the tissues. Oxygen is required for carbon monoxide production by Egregia menzies. A carbon monoxide-producing compound can be extracted by refluxing the macerated algal tissues in 0.01

M. W. Loewus; C. C. Delwiche

1963-01-01

224

A future for carbon taxes  

Microsoft Academic Search

Carbon taxes have been frequently advocated as a cost-effective instrument for reducing emissions. However, in the practice of environmental policies, only six countries have implemented taxes based on the carbon content of the energy products. In this paper, we evaluate carbon taxes with regard to their competitiveness, distributional and environmental impacts. The evidence shows that carbon taxes may be an

Andrea Baranzini; Jos Goldemberg; Stefan Speck

2000-01-01

225

Carbon Sequestration in Mine Residue  

Microsoft Academic Search

Mining of silicate rocks produces as waste a reactive, fine-grained residue that is an ideal feedstock for mineral sequestration of carbon. Natural weathering of Mg-silicate mine tailings is rapid because of the fine grain size, and produces mineral crusts that bind carbon. Stable and radiogenic carbon isotope fingerprinting on the minerals confirms an atmospheric carbon source. In active mines that

G. M. Dipple; G. Southam; I. Power; J. Thom; S. Wilson

2005-01-01

226

Stable Prenucleation Calcium Carbonate Clusters  

Microsoft Academic Search

Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion

Denis Gebauer; Antje Vlkel; Helmut Clfen

2008-01-01

227

Method for synthesizing carbon nanotubes  

DOEpatents

A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

Fan, Hongyou

2012-09-04

228

Carbon14 in tree rings  

Microsoft Academic Search

In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees,

William F. Cain; Hans E. Suess

1976-01-01

229

Carbon 14 in tree rings  

Microsoft Academic Search

In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees,

William F. Cain; Hans E. Suess

1976-01-01

230

Carbon Characterization Laboratory Report  

SciTech Connect

The newly completed Idaho National Laboratory (INL) Carbon Characterization Laboratory (CCL) is located in Lab-C20 of the Idaho National Laboratory Research Center. This laboratory was established under the Next Generation Nuclear Plant (NGNP) Project to support graphite research and development activities. The CCL is designed to characterize and test carbon-based materials such as graphite, carbon-carbon composites, and silicon-carbide composite materials. The laboratory is fully prepared to measure material properties for nonirradiated carbon-based materials. Plans to establish the laboratory as a radiological facility within the next year are definitive. This laboratory will be modified to accommodate irradiated materials, after which it can be used to perform material property measurements on both irradiated and nonirradiated carbon-based material. Instruments, fixtures, and methods are in place for preirradiation measurements of bulk density, thermal diffusivity, coefficient of thermal expansion, elastic modulus, Youngs modulus, Shear modulus, Poisson ratio, and electrical resistivity. The measurement protocol consists of functional validation, calibration, and automated data acquisition.

David Swank; William Windes; D.C. Haggard; David Rohrbaugh; Karen Moore

2009-03-01

231

Carbon management and biodiversity.  

PubMed

International efforts to mitigate human-caused changes in the Earth's climate are considering a system of incentives (debits and credits) that would encourage specific changes in land use that can help to reduce the atmospheric concentration of carbon dioxide. The two primary land-based activities that would help to minimize atmospheric carbon dioxide are carbon storage in the terrestrial biosphere and the efficient substitution of biomass fuels and bio-based products for fossil fuels and energy-intensive products. These two activities have very different land requirements and different implications for the preservation of biodiversity and the maintenance of other ecosystem services. Carbon sequestration in living forests can be pursued on lands with low productivity, i.e. on lands that are least suitable for agriculture or intensive forestry, and are compatible with the preservation of biodiversity over large areas. In contrast, intensive harvest-and-use systems for biomass fuels and products generally need more productive land to be economically viable. Intensive harvest-and-use systems may compete with agriculture or they may shift intensive land uses onto the less productive lands that currently harbor most of the Earth's biodiversity. Win-win solutions for carbon dioxide control and biodiversity are possible, but careful evaluation and planning are needed to avoid practices that reduce biodiversity with little net decrease in atmospheric carbon dioxide. Planning is more complex on a politically subdivided Earth where issues of local interest, national sovereignty, and equity come into play. PMID:12659806

Huston, Michael A; Marland, Gregg

2003-01-01

232

Mitochondrial carbonic anhydrase.  

PubMed Central

We have assayed carbonic anhydrase activity (carbonate dehydratase, carbonate hydro-lyase, EC 4.2.1.1) and bicarbonate permeability in suspensions of broken and intact guinea pig mitochondria by monitoring the disappearance of C16O18O. We found significant activity in preparations from liver and skeletal muscle, but not in preparations from heart muscle, brain, and kidney. Intact mitochondria containing carbonic anhydrase produce a two-phase acceleration of the disappearance of the labeled CO2, which indicates that the enzyme is located in a region more accessible to CO2 than to HCO3-. Acetazolamide inhibits the enzyme activity instantly in broken mitochondria but only after a delay in intact mitochondria, indicating that the enzyme is in a region not immediately accessible to the inhibitor. Sonication of mitochondria containing carbonic anhydrase activity releases the enzyme, which remains in the supernatant after sedimentation of the submitochondrial particles. This shows that mitochondrial carbonic anhydrase is in the matrix compartment and not in, or bound to, the inner membrane. The activity of the enzyme increases markedly with increasing pH. The enzyme activity of intact mitochondria is greater than that of the broken mitochondria at the same pH of the suspending fluid, corresponding to an intramitochondrial pH that is 0.2-0.5 unit more alkaline.

Dodgson, S J; Forster, R E; Storey, B T; Mela, L

1980-01-01

233

Carbon dioxide poisoning.  

PubMed

Carbon dioxide is a physiologically important gas, produced by the body as a result of cellular metabolism. It is widely used in the food industry in the carbonation of beverages, in fire extinguishers as an 'inerting' agent and in the chemical industry. Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death. Solid carbon dioxide may cause burns following direct contact. If it is warmed rapidly, large amounts of carbon dioxide are generated, which can be dangerous, particularly within confined areas. The management of carbon dioxide poisoning requires the immediate removal of the casualty from the toxic environment, the administration of oxygen and appropriate supportive care. In severe cases, assisted ventilation may be required. Dry ice burns are treated similarly to other cryogenic burns, requiring thawing of the tissue and suitable analgesia. Healing may be delayed and surgical intervention may be required in severe cases. PMID:16499405

Langford, Nigel J

2005-01-01

234

Carbon based prosthetic devices  

SciTech Connect

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project objective was to evaluate the use of carbon/carbon-fiber-reinforced composites for use in endoprosthetic devices. The application of these materials for the metacarpophalangeal (MP) joints of the hand was investigated. Issues concerning mechanical properties, bone fixation, biocompatibility, and wear are discussed. A system consisting of fiber reinforced materials with a pyrolytic carbon matrix and diamond-like, carbon-coated wear surfaces was developed. Processes were developed for the chemical vapor infiltration (CVI) of pyrolytic carbon into porous fiber preforms with the ability to tailor the outer porosity of the device to provide a surface for bone in-growth. A method for coating diamond-like carbon (DLC) on the articulating surface by plasma-assisted chemical vapor deposition (CVD) was developed. Preliminary results on mechanical properties of the composite system are discussed and initial biocompatibility studies were performed.

Devlin, D.J.; Carroll, D.W.; Barbero, R.S.; Archuleta, T. [Los Alamos National Lab., NM (US); Klawitter, J.J.; Ogilvie, W.; Strzepa, P. [Ascension Orthopedics (US); Cook, S.D. [Tulane Univ., New Orleans, LA (US). School of Medicine

1998-12-31

235

Carbon isotope effects in carbonate systems  

NASA Astrophysics Data System (ADS)

Global carbon cycle models require a complete understanding of the ? 13C variability of the Earth's C reservoirs as well as the C isotope effects in the transfer of the element among them. An assessment of ? 13C changes during CO 2 loss from degassing magmas requires knowledge of the melt-CO 2 carbon isotope fractionation. In order to examine the potential size of this effect for silicate melts of varying composition, 13C reduced partition functions were computed in the temperature range 275 to 4000 K for carbonates of varying bond strengths (Mg, Fe, Mn, Sr, Ba, Pb, Zn, Cd, Li, and Na) and the polymorphs of calcite. For a given cation and a given pressure the 13C content increases with the density of the carbonate structure. For a given structure the tendency to concentrate 13C increases with pressure. The effect of pressure (/10 kbar) on the size of the reduced partition function of aragonite varies with temperature; in the pressure range 1 to 10 5 bars the change is given by: ? 13C p average=-0.01796+0.06635? 10 3/T+0.006875? 10 6/T2 For calcite III the pressure effect is on average 1.4 larger than that for aragonite at all temperatures. The nature of the cation in a given structure type has a significant effect on the carbon isotope fractionation properties. The tendency to concentrate 13C declines in the series magnesite, aragonite, dolomite, strontianite, siderite, calcite, smithonite, witherite, rhodochrosite, otavite, cerrusite. For divalent cations a general expression for an estimation of the reduced partition function (?) from the reduced mass (? = [M Cation M Carbonate]/[M Cation + M Carbonate]) is: 1000 ln?=(0.032367-0.072563? 10 3/T-0.01073? 10 6/T2)??-14.003+29.953? 10 3/T+9.4610? 10 6/T2 For Mg-calcite the 13C content varies with the Mg concentration. The fractionation between Mg-calcite (X = mole fraction of MgCO 3) and calcite is given by: 1000 ln(? MgCalite- Calcite)=[0.013702-0.10957 10 3/T+1.35940 10 6/T2-0.329124 10 9/T3+0.0304160 10 12/T4] X1.5 The results of the computations were used together with previously published experimental vaporous CO 2-silicate melt fractionations to determine, at 1200C, a relationship between melt-CO 213C fractionation and melt composition, expressed as molecular proportions of the cations Mg, Fe, Mn, Ca, Na, K and Si and Al: 1000 ln? Melt- CO2=5.14 Mg+ Fe+ Mn+ Ca+ Na+ K/Si+ Al+0.86 A conceptual model to understand this relationship was developed. The results of the computations approximate closely the experimentally determined vaporous CO 2-CaCO 3 fractionations at high temperatures. Empirically derived dolomite-calcite and calcite-graphite 13C isotope geothermometers agree with results of the present work.

Deines, Peter

2004-06-01

236

Comparison between activated carbon, carbon xerogel and carbon nanotubes for the adsorption of the antibiotic ciprofloxacin  

Microsoft Academic Search

A comparison was made for the adsorption capacity of ciprofloxacin (CPX) on three types of carbon-based materials: activated carbon, carbon nanotubes and carbon xerogel. The obtained samples were characterised by adsorption of N2 at ?196C, determination of the point of zero charge and by temperature programmed desorption. The Langmuir and Freundlich models were used to describe the equilibrium isotherms obtained.

S. A. C. Carabineiro; T. Thavorn-amornsri; M. F. R. Pereira; P. Serp; J. L. Figueiredo

237

Studies and characterisations of various activated carbons used for carbon\\/carbon supercapacitors  

Microsoft Academic Search

Various activated carbons from the PICA Company have been tested in supercapacitor cells in order to compare their performances. The differences measured in terms of specific capacitance and cell resistance are presented. Porosity measurements made on activated carbon powders and electrode allowed a better understanding of the electrochemical behaviour of these activated carbons. In this way, the PICACTIF SC carbon

J Gamby; P. L Taberna; P Simon; J. F Fauvarque; M Chesneau

2001-01-01

238

Growth of carbon microtrees  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition process was developed which resulted in the growth of a unique carbon structure that resembles small trees. The trees are grown on a resistively heated graphite electrode where the temperature will reach 1500C in a matter of seconds. The nucleation of the carbon microtrees is typically assisted by an iron based catalyst. The structure of the carbon microtrees and the physical dimensions of the trees has been determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Deposited onto a carbon nanotube core is a structure that resembles vapor grown carbon fibers. The diameter of the tree increases with increasing distance from the substrate which is a result of the deposition conditions. The atomic structure of the stalk portion of the tree is turbostratic and is classified as rough laminar graphite. At the top of the tree is a cap. There are three different types of cap on the tree that is a function of the length of the tree and ultimately the deposition temperature at that distance. The cap can range from rough laminar pyrocarbon to smooth laminar pyrocarbon to isotropic pyrocarbon. The diameter of the cap is typically much larger than the stalk. The nucleation and growth mechanisms of the carbon microtrees was also investigated. The carbon nanotube core is nucleated and grown using an iron based catalyst particle. The mechanisms of pyrocarbon deposition are strongly affected by temperature. The deposition mechanisms can vary between being driven by gas phase kinetics, where the deposition is driven primarily by physisorption of large graphite molecules, and being driven by surface kinetics, where the deposition mechanism is through chemisorption of ethylene. The different deposition mechanisms result in the differences in microstructure between rough laminar and smooth laminar pyrocarbon. Finite element modelling of the deposition process was performed. It was found that the dominant factor in the deposition of pyrocarbon onto the carbon nanotube core, resulting in the carbon microtree structure, thermal gradient developed from the heating scheme of the substrate.

Nugent, John Michael

239

Studies on the synthesis of europium activated yttrium oxide by wet-chemical method  

Microsoft Academic Search

Europium activated yttrium oxide phosphor powders (Y2O3:Eu3+) were prepared from yttriumeuropium precursors obtained by wet-chemical method. With this purpose in view, precursors were prepared using the reagent simultaneous addition SimAdd technique from yttriumeuropium nitrate and chloride as rare-earth supplier and urea, ammonium oxalate, ammonium carbonate and oxalic acid as precipitating agents. Precursors, obtained under controlled concentration, temperature and pH conditions,

Laura Muresan; Elisabeth-Jeanne Popovici; Rodica Grecu; Lucian Barbu Tudoran

2009-01-01

240

Carbon copy deaths: carbon monoxide gas chamber.  

PubMed

The news media can exert a powerful influence over suicidal behaviour. It has been observed that like-minded individuals are able to preplan a group suicide method using modern communication technology in the form of websites and online chatrooms and mobile phone texting. A case of carbon monoxide (CO) poisoning is presented to illustrate the recent phenomenon of cyber suicides by suffocation from a burning barbecue (charcoal burner) in 'gas chamber' conversions. Although barbecues (BBQ) are very popular in Britain and widely available, there have been relatively few reported cases of copycat deaths from CO gas suffocation. PMID:18586213

Patel, F

2008-04-14

241

Towards an Autonomous Global Ocean Carbon Observatory  

Microsoft Academic Search

The ocean is by far the largest carbon reservoir in rapid communication with the atmosphere. Understanding both ocean carbon chemistry and ocean carbon biology are critical for carbon prediction. Marine carbon biomass accounts for roughly 50% of global carbon photosynthesis and a ~10 Pg C\\/year particulate carbon flux through 100 m into the deep sea. The latter export is commonly

J. K. Bishop

2007-01-01

242

Balancing the Global Carbon Budget  

NASA Astrophysics Data System (ADS)

The global carbon budget is, of course, balanced. The conservation of carbon and the first law of thermodynamics are intact. "Balancing the carbon budget" refers to the state of the science in evaluating the terms of the global carbon equation. The annual increases in the amount of carbon in the atmosphere, oceans, and land should balance the emissions of carbon from fossil fuels and deforestation. Balancing the carbon budget is not the real issue, however. The real issue is understanding the processes responsible for net sources and sinks of carbon. Such understanding should lead to more accurate predictions of future concentrations of CO2 and more accurate predictions of the rate and extent of climatic change. The recent past may be insufficient for prediction, however. Oceanic and terrestrial sinks that have lessened the rate of growth in atmospheric CO2 until now may diminish as feedbacks between the carbon cycle and climate become more prominent.

Houghton, R. A.

2007-05-01

243

Characterisation of Carbon Structure  

Microsoft Academic Search

\\u000a With its central position in the first full row of the Mendeleev classification (1s2, 22, 2p2), the elemmt carbon exhibits unique bonding possibilities. Cabon can bond to numerous other elements and fonn different bonding\\u000a with itself (catenation, illustrated in Fig. 1). Bonding in carbon materials controls tiiree major regimes:\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a Solids, with ?-bonds only, fonn 3D-structures which are rigid and

X. Bourrat

244

Ultrahard carbon nanocomposite films  

SciTech Connect

Modest thermal annealing to 600 C of diamondlike amorphous-carbon (a-C) films grown at room temperature results in the formation of carbon nanocomposites with hardness similar to diamond. These nanocomposite films consist of nanometer-sized regions of high density a-C embedded in an a-C matrix with a reduced density of 5--10%. The authors report on the evolution of density and bonding topologies as a function of annealing temperature. Despite a decrease in density, film hardness actually increases {approximately} 15% due to the development of the nanocomposite structure.

SIEGAL,MICHAEL P.; TALLANT,DAVID R.; PROVENCIO,PAULA P.; OVERMYER,DONALD L.; SIMPSON,REGINA L.; MARTINEZ-MIRANDA,L.J.

2000-01-27

245

Carbon Capture and Storage  

SciTech Connect

Carbon capture and sequestration (CCS) is the long-term isolation of carbon dioxide from the atmosphere through physical, chemical, biological, or engineered processes. This includes a range of approaches including soil carbon sequestration (e.g., through no-till farming), terrestrial biomass sequestration (e.g., through planting forests), direct ocean injection of CO{sub 2} either onto the deep seafloor or into the intermediate depths, injection into deep geological formations, or even direct conversion of CO{sub 2} to carbonate minerals. Some of these approaches are considered geoengineering (see the appropriate chapter herein). All are considered in the 2005 special report by the Intergovernmental Panel on Climate Change (IPCC 2005). Of the range of options available, geological carbon sequestration (GCS) appears to be the most actionable and economic option for major greenhouse gas reduction in the next 10-30 years. The basis for this interest includes several factors: (1) The potential capacities are large based on initial estimates. Formal estimates for global storage potential vary substantially, but are likely to be between 800 and 3300 Gt of C (3000 and 10,000 Gt of CO{sub 2}), with significant capacity located reasonably near large point sources of the CO{sub 2}. (2) GCS can begin operations with demonstrated technology. Carbon dioxide has been separated from large point sources for nearly 100 years, and has been injected underground for over 30 years (below). (3) Testing of GCS at intermediate scale is feasible. In the US, Canada, and many industrial countries, large CO{sub 2} sources like power plants and refineries lie near prospective storage sites. These plants could be retrofit today and injection begun (while bearing in mind scientific uncertainties and unknowns). Indeed, some have, and three projects described here provide a great deal of information on the operational needs and field implementation of CCS. Part of this interest comes from several key documents written in the last three years that provide information on the status, economics, technology, and impact of CCS. These are cited throughout this text and identified as key references at the end of this manuscript. When coupled with improvements in energy efficiency, renewable energy supplies, and nuclear power, CCS help dramatically reduce current and future emissions (US CCTP 2005, MIT 2007). If CCS is not available as a carbon management option, it will be much more difficult and much more expensive to stabilize atmospheric CO{sub 2} emissions. Recent estimates put the cost of carbon abatement without CCS to be 30-80% higher that if CCS were to be available (Edmonds et al. 2004).

Friedmann, S

2007-10-03

246

Carbon Nanotube templated structures  

NASA Astrophysics Data System (ADS)

Carbon nano tubes are of great interest to science due to their strong mechanical and exotic electrical properties. Nano tubes have potential application in transistors, micro electrical mechanical devices (MEMS), and structural materials. We have been using nanotube forests as a template to fabricate larger scale structures. The nanotube template is infiltrated with another material (like silicon or carbon). This infiltration can be thin to stabilize the forest and make a porous structure or thick to make a solid structure. Different methods employed at Brigham Young University of patterning, growing, and infiltrating nano tubes are presented on a poster along with applications.

Wyman, Ricky; Davis, Robert; Vanfleet, Richard; Song, Jun

2009-10-01

247

Nanomodified Carbon/Carbon Composites for Intermediate Temperature.  

National Technical Information Service (NTIS)

An improved Carbon/Carbon Composite (CCC) with enhanced thermo- oxidative resistant performance at intermediate temperatures (371 to 650 C) is being developed. A nanophase is introduced into the CCC prior to cure for improved and maintained mechanical str...

G. E. Wissler J. H. Koo L. A. Pilato

2007-01-01

248

Ecosystem carbon storage: Squeezing the Arctic carbon balloon  

NASA Astrophysics Data System (ADS)

The advancement of trees into Arctic tundra can increase total aboveground carbon storage. A study now shows, however, that greater plant growth also enhances belowground decomposition, resulting in a net loss of carbon from the ecosystem.

Kane, Evan S.

2012-12-01

249

Development of carbon-carbon composites from solvent extracted pitch.  

National Technical Information Service (NTIS)

There are several methods used to fabricate carbon-carbon composites. One used extensively in the fabrication of aerospace components such as rocket nozzles and reentry vehicle nosetips, as well as commercial components for furnace fixturing and glass man...

1996-01-01

250

Carbon/Carbon and Ceramic Composites Made by Aerospatiale.  

National Technical Information Service (NTIS)

Inorganic composites devoted to strategic and space applications are considered. The processing and properties of carbon/carbon and ceramic composites are considered. Present and future applications are discussed.

B. Capdepuy

1992-01-01

251

Development of Large Pyrolytic Carbon\\/Carbon Felt Cones  

Microsoft Academic Search

The problems of producing chemically vapor deposited (CVD) carbon\\/carbon felt composites cones suitable for reentry heat shields were studies and full-scale parts were produced. These problems included the fabrication of seamless rayon cones.

H. O. Pierson; J. F. Smatana

1969-01-01

252

Development of carbon-carbon composites from solvent extracted pitch  

SciTech Connect

There are several methods used to fabricate carbon-carbon composites. One used extensively in the fabrication of aerospace components such as rocket nozzles and reentry vehicle nosetips, as well as commercial components for furnace fixturing and glass manufacturing, is the densification of a woven preform with molten pitch, and the subsequent conversion of the pitch to graphite through heat treatment. Two types of pitch are used in this process; coal tar pitch and petroleum pitch. The objective of this program was to determine if a pitch produced by the direct extraction of coal could be used as a substitute for these pitches in the fabrication of carbon-carbon composites. The program involved comparing solvent extracted pitch with currently accepted pitches and rigidizing a carbon-carbon preform with solvent extracted pitch for comparison with carbon-carbon fabricated with currently available pitch.

NONE

1996-06-24

253

Water and Carbon Removal from Carbon Dioxide Reduction Systems.  

National Technical Information Service (NTIS)

Methods suitable for use in a weightless environment for removing water and carbon from carbon dioxide reduction process systems were investigated. Water removal studies were conducted using a porous metal, plate-type, condenser-separator to remove the wa...

A. D. Babinsky S. J. Derezinski

1966-01-01

254

An Ultrasonic Nondestructive Method for Evaluating Carbon\\/Carbon Composites  

Microsoft Academic Search

In this work, especially carbon\\/carbon (C\\/C) composites are one of the few materials that are suitable for structural applications at high temperature environments. Characterization and integrity of carbon\\/carbon(C\\/C) composite materials should be evaluated because of its inhomogeneity and composite. A C\\/C composite material was nondestructively characterized and a technique was developed to measure ultrasonic velocity in C\\/C composites using automated

K. H. Im; D. K. Hsu; S. J. Song; H. Cho; J. W. Park; Y. S. Kweon; J. K. Sim; I. Y. Yang

2006-01-01

255

Micromechanical Modeling of Porous Carbon\\/Carbon Composites  

Microsoft Academic Search

A procedure to model fiber-reinforced composites containing pores of irregular shapes is presented. Closed-form expressions for contributions of fibers and pores into effective elastic moduli are provided. The procedure is applied to predict the transverse elastic properties of unidirectional carbon\\/carbon composites (carbon fibers in pyrolytic carbon matrix) densified by chemical vapor infiltration. Infiltration treatment results in the formation of irregularly

I. Tsukrov; R. Piat; J. Novak; E. Schnack

2005-01-01

256

Carbon dioxide absorption with aqueous potassium carbonate promoted by piperazine  

Microsoft Academic Search

Many commercial processes for the removal of carbon dioxide from high-pressure gases use aqueous potassium carbonate systems promoted by secondary amines. This paper presents thermodynamic and kinetic data for aqueous potassium carbonate promoted by piperazine. Research has been performed at typical absorber conditions for the removal of CO2 from flue gas.Piperazine, used as an additive in 2030wt% potassium carbonate, was

J. Tim Cullinane; Gary T. Rochelle

2004-01-01

257

CarbonSat Constellation  

NASA Astrophysics Data System (ADS)

1 Carbon dioxide (CO2) and methane (CH4) are the most important manmade greenhouse gases (GHGs) which are driving global climate change. Currently, the CO2 measurements from the ground observing network are still the main sources of information but due to the limited number of measurement stations the coverage is limited. In addition, CO2 monitoring and trading is often based mainly on bottom-up calculations and an independent top down verification is limited due to the lack of global measurement data with local resolution. The first CO2 and CH4 mapping from SCIAMACHY on ENVISAT shows that satellites add important missing global information. Current GHG measurement satellites (GOSAT)are limited either in spatial or temporal resolution and coverage. These systems have to collect data over a year or even longer to produce global regional fluxes products. Conse-quently global, timely, higher spatial resolution and high accuracy measurement are required for: 1. A good understanding of the CO2 and CH4 sources and sinks for reliable climate predic-tion; and 2. Independent and transparent verification of accountable sources and sinks in supporting Kyoto and upcoming protocols The CarbonSat constellation idea comes out the trade off of resolution and swath width during CarbonSat mission definition studies. In response to the urgent need to support the Kyoto and upcoming protocols, a feasibility study has been carried out. The proposed solution is a constellation of five CarbonSat satellites in 614km LTAN 13:00, which is able to provide global, daily CO2 and CH4 measurement everywhere on the Earth with high spatial resolution 2 2 km and low uncertainty lt;2ppm (CO2) and lt;8ppb (CH4). The unique global daily measurement capability significantly increases the number of cloud free measurements, which enables more reliable services associated with reduced uncertainty, e.g. to 0.15ppm (CO2) per month in 10km and even more timely products. The CarbonSat Constellation in combination with inverse modelling techniques will be able to provide information services, such as global quarterly 1. CO2 and CH4 regional flux updates 2. CO2 emission reporting from hot spots e.g. the power plant 3. CH4 emission reporting from hot spots e.g. the pipeline/oil and gas fields. The team led by the industry partner -OHB now promotes an internationally coordinated CarbonSat constellation to provide operational services contributing to the independent iden-tification and verification of man-made & natural CO2 and CH4 emissions and claimed carbon sinks. It is proposed that the CarbonSat Constellation will be implemented through an internation-ally coordinated constellation. Each country contributes one satellite in the constellation and establishes its own ground station to provide data for national applications. A central coordi-nation will be set up for the constellation operation, data calibration and international data distribution. The proposed approach provides independence for each partner and is financially more feasible. In addition, the CarbonSat Constellation consortium could be a bridge/forum between developed countries and developing countries in establishing common understandings of and actions on the global climate change. The world wide transparency provided by this international forum is also critical in supporting Kyoto protocol and upcoming international agreement in man-made Greenhouse emission reduction. The paper will present the CarbonSat Constellation design and the proposed products/ services to verify CO2 and CH4 sources and sinks from a constellation of five CarbonSat satellites through a multilateral collaboration.

Sun, Wei; Tobehn, Carsten; Ernst, Robert; Bovensmann, Heinrich; Buchwitz, Michael; Burrows, John P.; Notholt, John

258

Management practices affects soil carbon dioxide emission and carbon storage  

Technology Transfer Automated Retrieval System (TEKTRAN)

Agricultural practices contribute about 25% of total anthropogenic carbon dioxide emission, a greenhouse gas responsible for global warming. Soil can act both as sink or source of atmospheric carbon dioxide. Carbon dioxide fixed in plant biomass through photosynthesis can be stored in soil as organi...

259

Carbon, Trade Policy, and Carbon Free Trade Areas  

Microsoft Academic Search

This paper discusses both the potential contribution that trade policy initiatives can make towards the achievement of significant global carbon emissions reduction and the potential impacts of proposals now circulating for carbon reduction motivated geographical trade arrangements, including carbon free trade areas. We first suggest that trade policy is likely to be a relatively minor consideration in climate change containment.

Yan Dong; John Whalley

2008-01-01

260

Carbon nanotubes coated by carbon nanoparticles of turbostratic stacked graphenes  

Microsoft Academic Search

Carbon nanotubes (CNTs) decorated by a high density of carbon nanoparticles of turbostratic graphene stacks have been fabricated by low energy hydrocarbon ion deposition at 700C. Transmission and scanning electron microscopy show that the carbon particles of turbostratic graphene stacks extend from the nanotube surface. The diameter of CNTs decreases with the increasing percentage of hydrogen in the gas phase.

Qintao Li; Zhichun Ni; Jinlong Gong; Dezhang Zhu; Zhiyuan Zhu

2008-01-01

261

IMPROVED SYNTHESIS OF CARBONATED SOYBEAN OIL IN SUPERCRITICAL CARBON DIOXIDE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Carbonates from oleochemical origin have shown recent promise in the cosmetics, filter, and detergent industries. Carbonates may also form building blocks for polymeric materials. Especially of interest are cyclic carbonates, which upon addition with an amine, form a non-isocyanate urethane. Many...

262

Carbon-hydrogen bonding in near-frictionless carbon  

Microsoft Academic Search

The uniquely low friction behavior of near-frictionless carbon (NFC) as compared to conventional diamondlike carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier transform infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface

Jackie A. Johnson; John B Woodford; Deepak Rajput; Alexander I Kolesnikov; John A Schleuter; Osman L Eryilmaz; Ali Erdemir

2008-01-01

263

Carbon accounting and carbon footprint more than just diced results?  

Microsoft Academic Search

Purpose The purpose of this paper is to discuss the growing public interest in climate protection and the desire for climate-friendly consumption which has led to a previously unimagined demand for Carbon Labels on products and various approaches to calculating the carbon footprint of firms or individual products. Design\\/methodology\\/approach A principal problem in calculating the carbon footprint is

Mario Schmidt

2009-01-01

264

Carbon Cycle 2.0: Berend Smit: Carbon Capture  

ScienceCinema

Feb. 3, 2010: Humanity emits more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future.

265

Electron Microscopy Studies of Carbon Nanotubes, Metal Encapsulation, Fullerides, and Dispersed Carbide  

Microsoft Academic Search

The structures and morphologies of some carbon -related nanometer-size particles, including carbon nanotubes, nanoparticles, palladium (Pa) fullerides, hafnium carbide (HfC) dispersoids, and encapsulated lanthanum carbide (LaC _2), yttrium carbide (YC _2), cobalt carbide (Co_2 C), and manganese carbides (Mn_3 C, Mn_5C_2, Mn_7C_3, and Mn _{23}C_6), have been studied with high-resolution electron microscopy (HREM), scanning transmission electron microscopy (STEM), electron energy-loss

Mingqi Liu

1994-01-01

266

The geochemistry of late Archaean microbial carbonate: implications for ocean chemistry and continental erosion history  

Microsoft Academic Search

Trace element concentrations and combined Sr- and Nd-isotope compositions were determined on stromatolitic carbonates (microbialites) from the 2.52 Ga Campbellrand carbonate platform (South Africa). Shale-normalised rare earth element and yttrium patterns of the ancient samples are similar to those of modern seawater in having positive La and Y anomalies and in being depleted in light rare earth elements. In contrast

Balz S Kamber; Gregory E Webb

2001-01-01

267

Effects of Different Fabrication Techniques on the Yttrium-Barium-Copper Oxide High Temperature Superconductor.  

National Technical Information Service (NTIS)

This study examines how several different parameters were changed in the yttrium-barium-copper oxide superconductor when the fabrication techniques were altered by using different barium precursors, including barium peroxide and barium carbonate; sinterin...

P. A. Rhea

1988-01-01

268

Carbon Nanotube Material Quality Assessment.  

National Technical Information Service (NTIS)

The nanomaterial activities at NASA Johnson Space Center focus on carbon nanotube production, characterization and their applications for aerospace systems. Single wall carbon nanotubes are produced by arc and laser methods. Characterization of the nanotu...

E. Sosa L. Yowell O. Gorelik P. Niolaev S. Arepalli

2006-01-01

269

Carbon dioxide as a feedstock.  

National Technical Information Service (NTIS)

This report is an overview on the subject of carbon dioxide as a starting material for organic syntheses of potential commercial interest and the utilization of carbon dioxide as a substrate for fuel production. It draws extensively on literature sources,...

Creutz Fujita

2000-01-01

270

PECVD Growth of Carbon Nanotubes.  

National Technical Information Service (NTIS)

Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has...

I. McAninch

2001-01-01

271

Carbon Nanotube Flow Sensors  

Microsoft Academic Search

We report that the flow of a liquid on single-walled carbon nanotube bundles induces a voltage in the sample along the direction of the flow. The voltage that was produced fit a logarithmic velocity dependence over nearly six decades of velocity. The magnitude of the voltage depended sensitively on the ionic conductivity and on the polar nature of the liquid.

Shankar Ghosh; A. K. Sood; N. Kumar

2003-01-01

272

Carbon-based electronics  

Microsoft Academic Search

The semiconductor industry has been able to improve the performance of electronic systems for more than four decades by making ever-smaller devices. However, this approach will soon encounter both scientific and technical limits, which is why the industry is exploring a number of alternative device technologies. Here we review the progress that has been made with carbon nanotubes and, more

Phaedon Avouris; Zhihong Chen; Vasili Perebeinos

2007-01-01

273

Life without Carbon?  

Microsoft Academic Search

Carbon is the centerpiece of all life on Earth and one of the most abundant elements in the Solar System and Sun-like stars. Yet alien biochemistries and one's choice of a definition of life offer possibility for other forms of life.

Manfred Cuntz; Peter E. Williams

2006-01-01

274

CarbonSat Constellation  

Microsoft Academic Search

1 Carbon dioxide (CO2) and methane (CH4) are the most important manmade greenhouse gases (GHGs) which are driving global climate change. Currently, the CO2 measurements from the ground observing network are still the main sources of information but due to the limited number of measurement stations the coverage is limited. In addition, CO2 monitoring and trading is often based mainly

Wei Sun; Carsten Tobehn; Robert Ernst; Heinrich Bovensmann; Michael Buchwitz; John P. Burrows; John Notholt

2010-01-01

275

Chloroplastic Carbonic Anhydrases  

Microsoft Academic Search

In biological systems the interconversion between CO2 and HCO?+H+ is catalyzed by carbonic anhydrases (CAs). They belong to three evolutionary unrelated gene families designated ?-, ?- and ?-CA1 with no significant sequence homologies between representatives of the different CA families. In the stroma of higher plant chloroplasts a ?-CA is one of the most abundant proteins. Its specific function is

Gran Samuelsson; Jan Karlsson

276

Bench Remarks: Carbon Dioxide.  

ERIC Educational Resources Information Center

|Discusses the properties of carbon dioxide in its solid "dry ice" stage. Suggests several demonstrations and experiments that use dry ice to illustrate Avogadro's Law, Boyle's Law, Kinetic-Molecular Theory, and the effects of dry ice in basic solution, in limewater, and in acetone. (TW)|

Bent, Henry A.

1987-01-01

277

Carbon dioxide fixation.  

National Technical Information Service (NTIS)

Solar carbon dioxide fixation offers the possibility of a renewable source of chemicals and fuels in the future. Its realization rests on future advances in the efficiency of solar energy collection and development of suitable catalysts for CO(sub 2) conv...

E. Fujita

2000-01-01

278

Fabrication of Carbon Nanotubes  

Microsoft Academic Search

The remarkable properties of carbon nanotubes give promise of a diverse array of revolutionary technologies and applications. Synthesis remains the key to their development. This article will review many of the current methods used for nanotube synthesis and the recent results towards achieving the goal of large-scale production with rational control of nanotube structure and properties.

Christopher T. Kingston; Benoit Simard

2003-01-01

279

Carbon Nanotube Quantum Resistors  

Microsoft Academic Search

The conductance of multiwalled carbon nanotubes (MWNTs) was found to be quantized. The experimental method involved measuring the conductance of nanotubes by re- placing the tip of a scanning probe microscope with a nanotube fiber, which could be lowered into a liquid metal to establish a gentle electrical contact with a nanotube at the tip of the fiber. The conductance

Stefan Frank; Philippe Poncharal; Z. L. Wang; Walt A. de Heer

1998-01-01

280

Carbon taxes and India  

Microsoft Academic Search

Using the Indian module of the Second Generation Model (SGM), we explore a reference case and three scenarios in which greenhouse gas emissions were controlled. Two alternative policy instruments (carbon taxes and tradable permits) were analyzed to determine comparative costs of stabilizing emissions at (1) 1990 levels (the 1X case), (2) two times the 1990 levels (the 2X case), and

K. A. Fisher-Vanden; P. R. Shukla; J. A. Edmonds; S. H. Kim; H. M. Pitcher

1997-01-01

281

Regularly coiled carbon nanotubes  

Microsoft Academic Search

Regularly coiled carbon nanotubes, their structure, and formation mechanism are puzzling questions. The first models were based on the very regular incorporation of a small fraction (of the order of 10%) of nonhexagonal (n-Hx) rings: (pentagons and heptagons) in a perfect hexagonal (Hx) lattice. It is difficult to understand by which mechanism takes place such a regular incorporation of isolated

Lszl P Bir; Gza I. Mrk; Philippe Lambin

2003-01-01

282

Coiled Carbon Nanotubes  

Microsoft Academic Search

Coiled carbon nanotubes (CCNTs) are CNTs with spiral structure. The CCNTs possess unique properties of helix, chirality and nonlinear mechanical behavior. It attracts great interests in the synthesis, growth mechanisms and application developments. The CCNTs is commonly synthesized by catalyst-supported chemical vapor deposition (CVD) and floating catalyst CVD. The selective production of CCNTs has been achieved. Based on the analysis

Jiaqi Huang; Qiang Zhang; Fei Wei

2009-01-01

283

Extrasolar Carbon Planets  

Microsoft Academic Search

We suggest that some extrasolar planets <~ 60 Earth masses will form substantially from silicon carbide and other carbon compounds. Pulsar planets and low-mass white dwarf planets are especially good candidate members of this new class of planets, but these objects could also conceivably form around stars like the Sun. This planet-formation pathway requires only a factor of two local

Marc J. Kuchner; S. Seager

2005-01-01

284

Carbon star effective temperatures  

Microsoft Academic Search

Possible methods for measuring the effective temperatures of individual carbon stars are discussed. Since calibrations of broad or narrow-band photometric colors is impractical at present, empirical corrections to narrow band color temperatures is the only valid procedure. The effective temperature of the star TW Oph is estimated, based on preliminary reduction of the occultation and associated photometry

S. T. Ridgway; G. H. Jacoby; R. R. Joyce; D. C. Wells

1981-01-01

285

Terrestrial carbon sequestration potential  

Microsoft Academic Search

Fossil fuel use and land use change that began over 200 years ago are driving the rapid increase in atmospheric content of CO2 and other greenhouse gases that may be impacting on climatic change. Enhanced terrestrial uptake of CO2 over the next 50 to 100 years has been suggested as a way to reclaim the 150 or more Pg carbon

METTING Blaine

286

Aqueous carbon dioxide monitor  

Microsoft Academic Search

This patent describes an apparatus for measuring low levels of carbon dioxide in water sample. It comprises: means for exchanging cations for hydrogen connected to a sample stream; a first membrane separator connected to the cation exchanging means, the first membrane separator having a first and second compartment with the first and second compartments being separated by a membrane, the

1991-01-01

287

Carbon Nanotube Solar Cells  

PubMed Central

We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

2012-01-01

288

AUSTRALIA'S CARBON FOOTPRINT  

Microsoft Academic Search

This paper gives an overview of the construction techniques and methods used to assign greenhouse gas accounts to industry sectors and of the use of inputoutput analysis to subsequently calculate the carbon footprint of Australia. The work is motivated by the introduction of an emissions-trading scheme in Australia, and by the need for policy to be developed around the direct

Richard Wood; Christopher J. Dey

2009-01-01

289

Changing Planet: Black Carbon  

NSDL National Science Digital Library

This video addresses two ways in which black carbon contributes to global warming - when in the atmosphere, it absorbs sunlight and generates heat, warming the air; when deposited on snow and ice, it changes the albedo of the surface. The video is effective in communicating about a problem frequently underrepresented in discussions of climate change and also public health.

Learn, Nbc; Universe, Windows T.

290

Electrowetting in Carbon Nanotubes  

Microsoft Academic Search

We demonstrate reversible wetting and filling of open single-wall carbon nanotubes with mercury by means of electrocapillary pressure originating from the application of a potential across an individual nanotube in contact with a mercury drop. Wetting improves the conductance in both metallic and semiconducting nanotube probes by decreasing contact resistance and forming a mercury nanowire inside the nanotube. Molecular dynamics

J. Y. Chen; A. Kutana; C. P. Collier; K. P. Giapis

2005-01-01

291

Carbon cloth supported electrode  

DOEpatents

A flow-by anode is disclosed made by preparing a liquid suspension of about to about 18% by weight solids, the solids comprising about 3.5 to about 8% of a powdered catalyst of platinum, palladium, palladium oxide, or mixtures thereof; about 60 to about 76% carbon powder (support) having a particle size less than about 20 m.mu.m and about 20 to about 33% of an inert binder having a particle size of less than about 500 m.mu.m. A sufficient amount of the suspension is poured over a carbon cloth to form a layer of solids about 0.01 to about 0.05 cm thick on the carbon cloth when the electrode is completed. A vacuum was applied to the opposite side of the carbon cloth to remove the liquid and the catalyst layer/cloth assembly is dried and compressed at about 10 to about 50 MPa's. The binder is then sintered in an inert atmosphere to complete the electrode. The electrode is used for the oxidation of sulfur dioxide in a sulfur based hybrid cycle for the decomposition of water.

Lu, Wen-Tong P. (Upper St. Clair, PA); Ammon, Robert L. (Baldwin both of, PA)

1982-01-01

292

Comparing Carbon Calculators  

NSDL National Science Digital Library

Carbon calculators, no matter how well intended as tools to help measure energy footprints, tend to be black boxes and can produce wildly different results, depending on the calculations used to weigh various energy factors. By comparing different calculators, learners can analyze which ones are the most accurate and relevant, and which are the most transparent.

Mccaffrey, Mark

293

Geoengineering and Carbon Management  

NASA Astrophysics Data System (ADS)

The term "geoengineering" was coined by Cesare Marchetti in the 1970's to describe a project that proposed to inject CO2 from electric generating plants into the deep ocean. The term has since been used to discuss a variety of projects that would involve purposeful, large-scale manipulation of the environment---primarily projects with the intent of mitigating anthropogenic changes in climate. Many activities that we now discuss under the title of "carbon management" have been previously identified as geoengineering. The term geoengineering is also used to describe possibilities for engineering the Earth's climate through large-scale manipulation of the energy balance, for example through manipulating the Earth's albedo. Studies are now showing more clearly that these two components, once treated separately under broad heading of "geoengineering", are linked. That is, for example, managing carbon through protecting or planting forests is also to manage the Earth's surface albedo and surface energy balance. Likewise, manipulating the albedo will alter the global carbon cycle. In this paper we discuss the evolution of the idea of geoengineering, summarizing the history of these technologies, and demonstrating how geoengineering includes, links, and melds with carbon management.

Marland, G.

2002-05-01

294

Hydrothermal carbonization of microalgae  

Microsoft Academic Search

Hydrothermal carbonization is a process in which biomass is heated in water under pressure to create a char product. With higher plants, the chemistry of the process derives primarily from lignin, cellulose and hemicellulose components. In contrast, green and blue-green microalgae are not lignocellulosic in composition, and the chemistry is entirely different, involving proteins, lipids and carbohydrates (generally not cellulose).

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

2010-01-01

295

Life without Carbon?  

NASA Astrophysics Data System (ADS)

Carbon is the centerpiece of all life on Earth and one of the most abundant elements in the Solar System and Sun-like stars. Yet alien biochemistries and one's choice of a definition of life offer possibility for other forms of life.

Cuntz, Manfred; Williams, Peter E.

2006-05-01

296

From Coffee to Carbon  

NSDL National Science Digital Library

In this activity, learners place cards featuring biological structures in order by their relative size from largest to smallest. The cards feature structures ranging from the carbon atom (340 pm) to a skin cell (30 μm) to a coffee bean (8 mm). This activity can also be used as a formative assessment or an anticipatory set.

Malone, Molly; Avery, Sheila; Conley, Thomas; Starr, Harmony

2008-01-01

297

Carbon Sequestration Monitoring Activities  

SciTech Connect

In its 'Carbon Sequestration Technology Roadmap and Program Plan 2007' the U.S. Department of Energy (DOE)'s Office of Fossil Energy National Energy Technology Laboratory (NETL) identified as a major objective extended field tests to fully characterize potential carbon dioxide (CO{sub 2}) storage sites and to demonstrate the long-term storage of sequestered carbon (p. 5). Among the challenges in this area are 'improved understanding of CO{sub 2} flow and trapping within the reservoir and the development and deployment of technologies such as simulation models and monitoring systems' (p. 20). The University of Wyoming (UW), following consultations with the NETL, the Wyoming State Geological Survey, and the Governor's office, identified potential for geologic sequestration of impure carbon dioxide (CO{sub 2}) in deep reservoirs of the Moxa Arch. The Moxa Arch is a 120-mile long north-south trending anticline plunging beneath the Wyoming Thrust Belt on the north and bounded on the south by the Uinta Mountains. Several oil and gas fields along the Moxa Arch contain accumulations of natural CO{sub 2}. The largest of these is the La Barge Platform, which encompasses approximately 800 square miles. Several formations may be suitable for storage of impure CO{sub 2} gas, foremost among them the Madison Limestone, Bighorn Dolomite, and Nugget Sandstone. This project responded to the challenges described above by preparing a geological site characterization study on the Moxa Arch. The project included four priority research areas: (A) geological characterization of geologic structure of the Arch, the fault, and fracture patterns of the target formations and caprocks, (B) experimental characterization of carbon dioxide-brine-rock reactions that may occur, (C) optimization of geophysical and numerical models necessary for measurement, monitoring and verification (MMV), and (D) a preliminary performance assessment. Research work to accomplish these goals was coordinated by one administrative task under the direction of Dr. Carol Frost, Professor of Geology and Geophysics (Task 1.0), and one task devoted to designing and creating an interdisciplinary, project-specific carbon cyberinfrastructure to support collaborative carbon dioxide sequestration research among University of Wyoming scientists and their collaborators, performed by Jeff Hammerlinck, Director of the Wyoming Geographic Information Science Center at the University of Wyoming (Task 1.5). The results of these tasks are presented in the Introduction and in Chapter 1, respectively.

Carol Frost

2010-11-30

298

Bioenergy, the Carbon Cycle, and Carbon Policy  

NASA Astrophysics Data System (ADS)

The evolving energy and land-use policies across North America and Africa provide critical case studies in the relationship between regional development, the management of natural resources, and the carbon cycle. Over 50 EJ of the roughly 430 EJ total global anthropogenic energy budget is currently utilized in the form of direct biomass combustion. In North America 3 - 4 percent of total energy is derived from biomass, largely in combined heat and power (CHP) combustion applications. By contrast Africa, which is a major consumer of 'traditional' forms of biomass, uses far more total bioenergy products, but largely in smaller batches, with quantities of 0.5 - 2 tons/capita at the household level. Several African nations rely on biomass for well over 90 percent of household energy, and in some nations major portions of the industrial energy supply is also derived from biomass. In much of sub-Saharan Africa the direct combustion of biomass in rural areas is exceeded by the conversion of wood to charcoal for transport to the cities for household use there. There are major health, and environmental repercussions of these energy flows. The African, as well as Latin American and Asian charcoal trade has a noticeable signature on the global greenhouse gas cycles. In North America, and notably Scandinavia and India as well, biomass energy and emerging conversion technologies are being actively researched, and provide tremendous opportunities for the evolution of a sustainable, locally based, energy economy for many nations. This talk will examine aspects of these current energy and carbon flows, and the potential that gassification and new silvicultural practices hold for clean energy systems in the 21st century. North America and Africa will be examined in particular as both sources of innovation in this field, and areas with specific promise for application of these energy technologies and biomass/land use practices to further energy and global climate management.

Kammen, D. M.

2003-12-01

299

The biocompatibility of carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes (CNT) are well-ordered, high aspect ratio allotropes of carbon. The two main variants, single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT) both possess a high tensile strength, are ultra-light weight, and have excellent chemical and thermal stability. They also possess semi- and metallic-conductive properties. This startling array of features has led to many proposed applications in the

S. K. Smart; A. I. Cassady; G. Q. Lu; D. J. Martin

2006-01-01

300

Soil carbon sequestration in phytoliths  

Microsoft Academic Search

The role of the organic carbon occluded within phytoliths (referred to in this text as PhytOC) in carbon sequestration in some soils is examined. The results show that PhytOC can be a substantial component of total organic carbon in soil. PhytOC is highly resistant to decomposition compared to other soil organic carbon components in the soil environments examined accounting for

Jeffrey F Parr; Leigh A Sullivan

2005-01-01

301

Plasma Processing for Carbon Nanomaterials  

NASA Astrophysics Data System (ADS)

Plasma is a useful tool to synthesize carbon nano-materials including diamond, fullerene, nanotube and graphene. This review introduces the overview of these carbon nano-materials produced by thermal or non-thermal plasmas and also the authors' work related to plasma-enhanced chemical vapor deposition of carbon nanotubes and its correlation with numerical simulation of CH4/H2 feedstock gas plasmas. The amount of carbon atoms in the CNTs grown and that calculated from simulation showed good agreement.

Suda, Yoshiyuki; Takikawa, Hirofumi; Tanoue, Hideto

302

Evolution and imaging of nanoparticles observed in laser ablated carbon plume  

Microsoft Academic Search

We report evidence of nanoparticles formation in laser ablated carbon plasma created by irradiating a graphite target with nanosecond neodymium doped yttrium aluminum garnet laser. The temporal evolution and spatial distribution of C2 molecules in the plasma is studied using optical emission spectroscopy, dynamic imaging and laser induced fluorescence techniques. The laser induced fluorescence spectrum and imaging of C2 fluorescence

Dheerendra Yadav; Varun Gupta; Raj K. Thareja

2009-01-01

303

Influence of chamber volume in single-walled carbon nanotube synthesis by an electric arc  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) were produced by an electric arc process in a low-pressure chamber with vertical electrodes using heterogeneous graphite anodes containing nickel and yttrium catalysts. The influence of the chamber volume (18, 25 and 60 L) and graphite grain size (1 and 100 m) of the anode on the resulting products was analysed. This was correlated with the

V Ramarozatovo; A Mansour; M Razafinimanana; M Monthioux; F Valensi; L No; M Masqure

2012-01-01

304

The Carbon Budget of California  

Microsoft Academic Search

The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide and methane greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government's recent inventory, California's carbon budget is presently dominated by fossil fuel emissions of CO2 (at >85% of total annual GHG emissions) to meet

C. S. Potter

2009-01-01

305

The carbon budget of California  

Microsoft Academic Search

The carbon budget of a region can be defined as the sum of annual fluxes of carbon dioxide (CO2) and methane (CH4) greenhouse gases (GHGs) into and out of the regional surface coverage area. According to the state government's recent inventory, California's carbon budget is presently dominated by 115 MMTCE per year in fossil fuel emissions of CO2 (>85% of

Christopher Potter

2010-01-01

306

A Search for Carbon Atoms.  

National Technical Information Service (NTIS)

Attempts were made to measure carbon atom concentration in graphite vapor by using optical absorption of the carbon resonance multiplet at 1657A. No carbon atoms could be detected in a variety of flow experiments. It was shown that this result was due to ...

A. G. Whittaker P. L. Kintner

1968-01-01

307

Dispersion toughened silicon carbon ceramics  

DOEpatents

Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

Wei, G.C.

1984-01-01

308

Full Carbon Account for Russia  

Microsoft Academic Search

The Forestry Project (FOR) at IIASA has produced a full carbon account (FCA) for Russia for 1990, together with scenarios for 2010. Currently, there are rather big question marks regarding the existing carbon accounts for Russia, and Russia is critical to the global carbon balance due to its size. IIASA is in a position to perform solid analysis of Russia

S. Nilsson; A. Shvidenko; V. Stolbovoi; M. Gluck; M. Jonas; M. Obersteiner

2000-01-01

309

Textured Carbon Surfaces on Copper.  

National Technical Information Service (NTIS)

A very thin layer of highly textured carbon is applied to a copper surface by a triode sputtering process. A carbon target and a copper substrate are simultaneously exposed to an argon plasma in a vacuum chamber. The resulting carbon surface is characteri...

A. N. Curren K. A. Jensen R. F. Roman

1984-01-01

310

The Structures & Properties of Carbon  

ERIC Educational Resources Information Center

|The four main forms of carbon--diamond, graphite, buckyballs, and carbon nanotubes (CNTs)--are an excellent vehicle for teaching fundamental principles of chemical bonding, material structure, and properties. Carbon atoms form a variety of structures that are intrinsically connected to the properties they exhibit. Educators can take advantage of

Castellini, Olivia M.; Lisensky, George C.; Ehrlich, Jennifer; Zenner, Greta M.; Crone, Wendy C.

2006-01-01

311

Carbon sequestration research and development  

Microsoft Academic Search

Predictions of global energy use in the next century suggest a continued increase in carbon emissions and rising concentrations of carbon dioxide (CO) in the atmosphere unless major changes are made in the way we produce and use energy--in particular, how we manage carbon. For example, the Intergovernmental Panel on Climate Change (IPCC) predicts in its 1995 ''business as usual''

Dave Reichle; John Houghton; Bob Kane; Jim Ekmann

1999-01-01

312

CARBON IN FORESTS: QUALITY MATTERS  

EPA Science Inventory

The nature of carbon in forests is discussed from the perspective of carbon sequestration and global climate change. Carbon inventories, specifically in the area of land use and forestry are reviewed for the Pacific Northwest. Areas vulnerable to climate change with respect to ca...

313

Raman spectroscopy of carbon nanotubes  

Microsoft Academic Search

The use of Raman spectroscopy to reveal the remarkable structure and the unusual electronic and phonon properties of single wall carbon nanotubes (SWNTs) is reviewed comprehensively. The various types of Raman scattering processes relevant to carbon nanotubes are reviewed, and the theoretical foundations for these topics are presented. The most common experimental techniques used to probe carbon nanotubes are summarized,

M. S. Dresselhaus; G. Dresselhaus; R. Saito; A. Jorio

2005-01-01

314

Carbon aerosols and atmospheric photochemistry  

Microsoft Academic Search

Carbon aerosols are produced by all combustion processes. This paper investigates some possible effects of heterogeneous reduction of atmospheric constituents on carbon aerosols. Reduction of HNO3, NO2, and 03 on carbon aerosols may be an important effect of increased air traffic that has not been considered to date. It is shown that if HNO3, NO2 and 03 are heterogeneously reduced

D. J. Lary; A. M. Lee; R. Toumi; M. J. Newchurch; M. Pirre; J. B. Renard

1997-01-01

315

Carbon dioxide absorption methanol process  

Microsoft Academic Search

A process is described for removing carbon dioxide from a feed stream of natural gas, having at least methane, ethane and heavier hydrocarbon, comprising: separating the feed stream in a first separator to form a first stream, having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane, and a second stream, having methane, carbon dioxide and

Apffel

1987-01-01

316

Carbon dioxide absorption methanol process  

Microsoft Academic Search

This patent describes a process for removing carbon dioxide from a feed stream of natural gas having at least methane, ethane and heavier. It comprises: first, separating the feed stream in a first separator to form a first stream having substantially all of the propane and heavier hydrocarbons and carbon dioxide and ethane and a second stream, having methane, carbon

Apffel

1989-01-01

317

Surface Chemical Analysis and Electrokinetic Properties of Spherical Hematite Particles Coated with Yttrium Compounds  

Microsoft Academic Search

We describe in this work the chemical and electrokinetic surface characterization of coreshell particles consisting of a practically spherical hematite nucleus coated by a layer of yttrium basic carbonate or yttrium oxide (obtained after calcination of the carbonate-coated particles, following the method of E. Matijevi? and B. Aiken (J. Colloid Interface Sci.126,645 (1988))). The morphological and surface characteristics of the

R. C. Plaza; J. D. G. Durn; A. Quirantes; M. J. Ariza; A. V. Delgado

1997-01-01

318

The fate of carbon in grasslands under carbon dioxide enrichment  

NASA Astrophysics Data System (ADS)

The concentration of carbon dioxide (CO2) in the Earth's atmosphere is rising rapidly, with the potential to alter many ecosystem processes. Elevated CO2 often stimulates photosynthesis, creating the possibility that the terrestrial biosphere will sequester carbon in response to rising atmospheric CO2 concentration, partly offsetting emissions from fossil-fuel combustion, cement manufacture, and deforestation,. However, the responses of intact ecosystems to elevated CO2 concentration, particularly the below-ground responses, are not well understood. Here we present an annual budget focusing on below-ground carbon cycling for two grassland ecosystems exposed to elevated CO2 concentrations. Three years of experimental CO2 doubling increased ecosystem carbon uptake, but greatly increased carbon partitioning to rapidly cycling carbon pools below ground. This provides an explanation for the imbalance observed in numerous CO2 experiments, where the carbon increment from increased photosynthesis is greater than the increments in ecosystem carbon stocks. The shift in ecosystem carbon partitioning suggests that elevated CO2 concentration causes a greater increase in carbon cycling than in carbon storage in grasslands.

Hungate, Bruce A.; Holland, Elisabeth A.; Jackson, Robert B.; Chapin, F. Stuart; Mooney, Harold A.; Field, Christopher B.

1997-08-01

319

Carbon and carbon-14 in lunar soil 14163  

SciTech Connect

Carbon is removed from the surface of lunar soil 14163 size fractions by combustions at 500 and 1000/sup 0/C in an oxygen stream and the carbon contents and the carbon-14 activities are measured. The carbon contents are inversely correlated with grain size. A measured carbon content of 198 ppM for bulk 14163, obtained by combining the size fraction results, is modified to 109 +- 12 ppM by a carbon contamination correction. This value is in accord with a previous determination, 110 ppM, for bulk 14163. The small (< 53 ..mu..) grains of 14163 had more combusted carbon-14 activity, 31.2 +- 2.5 dpm /kg, than the large (> 53 ..mu..) grains, 11.2 +- 2.0 dpm/kg. The combusted carbon and carbon-14 are attributed mainly to solar-wind implantation. Melt extractions of carbon-14 from the combusted soil samples gave essentially identical activities, 21.0 +- 1.5 and 19.2 +- 2.0 dpm/kg for the small and large grains, and are attributed to cosmic-ray spallation-produced carbon-14.

Fireman, E.L.; Stoenner, R.W.

1981-01-01

320

Authigenic carbonate and the history of the global carbon cycle.  

PubMed

We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O(2) or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic. PMID:23372007

Schrag, Daniel P; Higgins, John A; Macdonald, Francis A; Johnston, David T

2013-02-01

321

Synthesis of Linear Acetylenic Carbon: The "sp" Carbon Allotrope  

NASA Astrophysics Data System (ADS)

A carbon allotrope based on "sp" hybridization containing alternating triple and single bonds (an acetylenic or linear carbon allotrope) has been prepared. Studies of small (8 to 28 carbon atoms) acetylenic carbon model compounds show that such species are quite stable (130^circ to 140^circC) provided that nonreactive terminal groups or end caps (such as tert-butyl or trifluoromethyl) are present to stabilize these molecules against further reactions. In the presence of end capping groups, laser-based synthetic techniques similar to those normally used to generate fullerenes, produce thermally stable acetylenic carbon species capped with trifluoromethyl or nitrile groups with chain lengths in excess of 300 carbon atoms. Under these conditions, only a negligible quantity of fullerenes is produced. Acetylenic carbon compounds are not particularly moisture or oxygen sensitive but are moderately light sensitive.

Lagow, Richard J.; Kampa, Joel J.; Wei, Han-Chao; Battle, Scott L.; Genge, John W.; Laude, David A.; Harper, Carla J.; Bau, Robert; Stevens, Raymond C.; Haw, James F.; Munson, Eric

1995-01-01

322

Human Impacts and Management of Carbon Sources  

Microsoft Academic Search

The energy system dominates human-induced carbon flows on our planet. Globally, six billion tons of carbon are contained in the fossil fuels removed from below the ground every year. More than 90% of the carbon in fossil fuels is used for energy purposes, with carbon dioxide as the carbon product and the atmosphere as the initial destination for the carbon

S. Benson; J. Edmonds; R. Socolow; T. Surles

1999-01-01

323

Functional materials based on carbon nanotubes: Carbon nanotube actuators and noncovalent carbon nanotube modification  

Microsoft Academic Search

Carbon nanotubes have attractive inherent properties that encourage the development of new functional materials and devices based on them. The use of single wall carbon nanotubes as electromechanical actuators takes advantage of the high mechanical strength, surface area and electrical conductivity intrinsic to these molecules. The work presented here investigates the mechanisms that have been discovered for actuation of carbon

Leonard S. Fifield

2003-01-01

324

Synthetic methodologies for carbon nanomaterials.  

PubMed

Carbon nanomaterials have advanced rapidly over the last two decades and are among the most promising materials that have already changed and will keep on changing human life. Development of synthetic methodologies for these materials, therefore, has been one of the most important subjects of carbon nanoscience and nanotechnology, and forms the basis for investigating the physicochemical properties and applications of carbon nanomaterials. In this Research News article, several synthetic strategies, including solvothermal reduction, solvothermal pyrolysis, hydrothermal carbonization, and soft-chemical exfoliation are specifically discussed and highlighted, which have been developed for the synthesis of novel carbon nanomaterials over the last decade. PMID:20526999

Liu, Zhaoping; Zhou, Xufeng; Qian, Yitai

2010-05-01

325

Modeling the geochemical carbon cycle  

SciTech Connect

The authors have modeled the slow, long-term cycle in which geochemical processes transfer carbon among land, sea, and atmosphere. The model suggests that the earth may have been warmed in the past when buildups of atmospheric carbon dioxide enhanced the greenhouse effect. The model predicts that the slow natural fluctuations of atmospheric carbon dioxide may rival or even exceed the much faster changes that arise from human activities or from the biological carbon cycle. The main purpose in modeling the geochemical carbon cycle is to expose how little is known about the rates of important global processes and how seemingly unrelated processes (such as tectonism and climate) are linked.

Berner, R.A.; Lasaga, A.C.

1989-03-01

326

Defects in carbon nanostructures  

SciTech Connect

Previous high-resolution electron microscopy (HREM) observations of carbon nanotubes have led to a Russian doll' structural model that is based on hollow concentric cylinders capped at both ends. The structures of the carbon nanotubes and particles were characterized here by bulk physical and chemical property measurements. The individual nanostructure is as compressible as graphite in the c-axis, and such nanostructures can be intercalated with potassium and rubidium, leading to a saturation composition of Mc[sub 8]'. These results are counter to expectations that are based on a Russian doll structure. HREM after intercalation with potassium and deintercalation indicates that individual nanoparticles are a paper-mache' of smaller graphite layers. Direct current magnetization and electron spin resonance measurements indicate that the electronic properties of the nanostructures are distinctly different from those of graphite. Although the nanostructures have distinct morphologies and electronic properties, they are highly defective and have a local structure similar to turbostratic graphite.

Zhou, O.; Fleming, R.M.; Murphy, D.W.; Chen, C.H.; Haddon, R.C.; Ramirez, A.P.; Glarum, S.H. (AT T Bell Laboratories, Murray Hill, NJ (United States))

1994-03-25

327

Analysis of carbon monoxide.  

PubMed

The degree of exposure to carbon monoxide is most often assessed by measuring the blood carboxyhaemoglobin saturation. This measurement is relevant to investigations of acute accidental or deliberate poisoning and of chronic exposure in a domestic or work place environment. Simple spectrophotometric methods based on differential protein precipitation or dithionite reduction are prone to interference from other haemoglobin pigments and are imprecise for low-level estimations. Automated spectrophotometric devices (CO-oximeters) that estimate simultaneously total haemoglobin, percentage oxyhaemoglobin and percentage carboxyhaemoglobin have acceptable accuracy for carboxyhaemoglobin saturation levels of > 5% and are recommended for most clinical purposes. For the investigation of low-level exposure and the detection of increased haemolysis in neonates, more sensitive methods involving the release of carbon monoxide and its measurement by gas chromatography are required. Gas chromatographic methods are also appropriate when examining post-mortem blood samples where putrefaction or heat stress has resulted in a significant change in haemoglobin composition. PMID:12117442

Widdop, Brian

2002-07-01

328

Carbon Monoxide Targeting Mitochondria  

PubMed Central

Mitochondria present two key roles on cellular functioning: (i) cell metabolism, being the main cellular source of energy and (ii) modulation of cell death, by mitochondrial membrane permeabilization. Carbon monoxide (CO) is an endogenously produced gaseoustransmitter, which presents several biological functions and is involved in maintaining cell homeostasis and cytoprotection. Herein, mitochondrion is approached as the main cellular target of carbon monoxide (CO). In this paper, two main perspectives concerning CO modulation of mitochondrial functioning are evaluated. First, the role of CO on cellular metabolism, in particular oxidative phosphorylation, is discussed, namely, on: cytochrome c oxidase activity, mitochondrial respiration, oxygen consumption, mitochondrial biogenesis, and general cellular energetic status. Second, the mitochondrial pathways involved in cell death inhibition by CO are assessed, in particular the control of mitochondrial membrane permeabilization.

Queiroga, Claudia S. F.; Almeida, Ana S.; Vieira, Helena L. A.

2012-01-01

329

Carbonate fuel cell matrix  

DOEpatents

A carbonate fuel cell matrix comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles.

Farooque, Mohammad (Huntington, CT); Yuh, Chao-Yi (New Milford, CT)

1996-01-01

330

Carbonate fuel cell matrix  

DOEpatents

A carbonate fuel cell matrix is described comprising support particles and crack attenuator particles which are made platelet in shape to increase the resistance of the matrix to through cracking. Also disclosed is a matrix having porous crack attenuator particles and a matrix whose crack attenuator particles have a thermal coefficient of expansion which is significantly different from that of the support particles, and a method of making platelet-shaped crack attenuator particles. 8 figs.

Farooque, M.; Yuh, C.Y.

1996-12-03

331

Closing carbon cycles  

Microsoft Academic Search

Fossil fuels are used as raw materials for the manufacture of synthetic organic materials, e.g. plastics, fibres, synthetic rubber,\\u000a paints, solvents, fertilisers, surfactants, lubricants and bitumen. Since fossil carbon is embodied in these products they may be particularly relevant to climate change. This thesis analyses the production, use and waste management of synthetic organic\\u000a materials. The main research questions are

Martin Patel

1999-01-01

332

Barium carbonate intoxication  

Microsoft Academic Search

A 22-year-old man attempted to commit suicide by swallowing an unknown amount of barium carbonate dissolved in hydrochloric acid. Shortly after ingestion, he developed crampy abdominal pain and generalized muscle weakness. About 2 h later, respiratory failure ensued necessitating orotracheal intubation and mechanical ventilation. Concomitantly, life-threatening arrhythmias including ventricular fibrillation occurred, and he had to be resuscitated for 45 min.

Th. F. Schorn; Ch. Olbricht; A. Schler; A. Franz; K. Wittek; H.-J. Balks; E. Hausmann; H.-H. Wellhoener

1991-01-01

333

Carbon Nanotubes Toxicity  

NASA Astrophysics Data System (ADS)

We describe current and possible future developments in nanotechnology for biological and medical applications. Nanostructured, composite materials for drug delivery, biosensors, diagnostics and tumor therapy are reviewed as examples, placing special emphasis on silica composites. Carbon nanotubes are discussed as a primary example of emerging nanomaterials for many of the above-mentioned applications. Toxicity effects of this novel nanomaterial are discussed and the need for further study of potential hazards for human health, professionally exposed workers and the environment is motivated.

Bellucci, Stefano

334

Balancing Atmospheric Carbon Dioxide  

Microsoft Academic Search

ABSTRACT Rising carbon dioxide and global temperatures are causing increasingworldwide concern, and pressure towards an internationallaw of the atmosphere is rapidly escalating, yet widespread misconceptions about the greenhouse effect's inevitability, time scale, and causes have inhibited effective consensus and action. Observations from Antarctic ice cores, Amazonian rainforests, and Caribbean coral reefs suggest that the biological,effects,of climate,change,may,be more,severe,than,climate,models,predict. Efforts to limit

J. Goreau

335

Assessing geochemical carbon management  

Microsoft Academic Search

The challenge of reversing rising atmospheric CO2 concentrations is growing with the continued expansion of CO2-emitting energy infrastructure throughout the world and with the lack of coordinated, effective measures to manage and reduce\\u000a emissions. Given this situation, it is prudent for society to explore all potential carbon management options, including those\\u000a with seemingly low probability for success. Recent initiatives for

Jennie C. Stephens; David W. Keith

2008-01-01

336

Amorphous Carbon Nanospheres  

ScienceCinema

Amorphous carbon nanosphere used as the anode material for Li-intercalation in Lithium-ion energy storage. This structure was obtained through a thermal annealing process at a temperature of 3000 degree Kelvin, simulated using the LAMMPS molecular dynamics code on the LCRC Fusion resource. Science: Kah Chun Lau, Larry Curtiss, Argonne National Laboratory Visualization: Aaron Knoll, Mark Hereld, Michael E. Papka, Argonne National Laboratory

337

Substitutional carbon in germanium  

Microsoft Academic Search

Carbon impurities implanted into single-crystalline germanium are studied with infrared absorption spectroscopy and ion channeling. After implantation of 12C+ at room temperature and subsequent annealing at 350 C, a sharp infrared absorption line is observed at 531 cm-1. When 12C+ is substituted by 13C+, the line shifts down in frequency to 512 cm-1 and co-implantation of 12C+ and 13C+ does

L. Hoffmann; J. C. Bach; B. Bech Nielsen; P. Leary; R. Jones; S. autberg

1997-01-01

338

Carbonate fuel cell anodes  

Microsoft Academic Search

A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel\\/iron, cobalt\\/iron, nickel\\/iron\\/aluminum, cobalt\\/iron\\/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about

Rafael A. Donado; Kenneth E. Hrdina; Robert J. Remick

1993-01-01

339

Coefficients of thermal expansion for a carbon-carbon composite  

SciTech Connect

From the published data, carbon-carbon composites possess many unique properties at high temperature. They retain their room temperature strength in excess of 2200{degrees}C. The low coefficients of thermal expansion (CTE) and the property of non-wetting by molten metals make carbon-carbon composites excellent candidates for applications in the LIS program. Among these unique properties, CTE is the most important factor for the LIS program. In seeking to evaluate typical CTE's we obtained complementary samples of selected carbon-carbon specimens. These samples were laminates with (0{sub 2}){sub s}, (0{sub 2}90{sub 2}){sub s} and ({plus minus}45){sub s} orientations. These results indicated that the selected carbon-carbon composites are almost isotropic in thermal expansion. The CTE's are slightly negative at low temperature and become positive at high temperature. The exact values are shown in the figures. In order to determine the outgassing of carbon-carbon composites, two samples were tested in vacuum. The results have shown that the outgassing can not be neglected. 8 figs.

Feng, W.W.; Hoheisel, T.H.

1989-11-17

340

Quantitative analysis of carbon in silicon carbide coated with carbon.  

PubMed

Nonconductive specimens for scanning electron microscopy or X-ray microanalysis are coated with conductive carbon in order to reduce charging. But carbon film absorbs X-ray fluxes causing errors in measuring chemical composition. Especially when the carbon content is measured, carbon coating not only blocks X-rays but also becomes a source of carbon X-rays. It is thus necessary to determine how much errors are induced by carbon coating, and how thick coating is allowed for the accurate measurement. In this study, quantitative analysis of carbon on silicon carbide with carbon coating films was attempted by electron probe microanalyzer. It was found that measured carbon content increased in a nonlinear manner up to 40% with a film thickness, whereas silicon content decreased slightly. Carbon X-ray intensity was determined by computer simulation, which increased in a linear manner with the thickness. The discrepancy was due to a nucleation and growth of islands and thus a change of density with a thickening of coating film. PMID:23920162

Lee, Hongrim; Kim, Junsu; Yun, Jondo

2013-08-01

341

Carbon K-edge Spectra of Carbonate Minerals  

SciTech Connect

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

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

2010-01-01

342

Interfaces of propylene carbonate  

NASA Astrophysics Data System (ADS)

Propylene carbonate (PC) wets graphite with a contact angle of 31 at ambient conditions. Molecular dynamics simulations agree with this contact angle after 40% reduction of the strength of graphite-C atom Lennard-Jones interactions with the solvent, relative to the models used initially. A simulated nano-scale PC droplet on graphite displays a pronounced layering tendency and an Aztex pyramid structure for the droplet. Extrapolation of the computed tensions of PC liquid-vapor interface estimates the critical temperature of PC accurately to about 3%. PC molecules lie flat on the PC liquid-vapor surface and tend to project the propyl carbon toward the vapor phase. For close PC neighbors in liquid PC, an important packing motif stacks carbonate planes with the outer oxygen of one molecule snuggled into the positively charged propyl end of another molecule so that neighboring molecule dipole moments are approximately antiparallel. The calculated thermal expansion coefficient and the dielectric constants for liquid PC agree well with experiment. The distribution of PC molecule binding energies is closely Gaussian. Evaluation of the density of the coexisting vapor then permits estimation of the packing contribution to the PC chemical potential and that contribution is about two thirds of the magnitude of the contributions due to attractive interactions, with opposite sign.

You, Xinli; Chaudhari, Mangesh I.; Pratt, Lawrence R.; Pesika, Noshir; Aritakula, Kalika M.; Rick, Steven W.

2013-03-01

343

Carbon in primitive meteorites  

NASA Astrophysics Data System (ADS)

No meteorites are truly primitive, in the sense of being pristine collections of interstellar grains or solar-nebular condensates. Nonetheless, some chrondritic meteorites have been so little altered by secondary processing that they are commonly termed primitive and it is almost a definition of such chondrites that they contain significant quantities of carbon. Most of that carbon is of apparently local, i.e., solar-system, origin but a proportion that ranges from trace, in some cases, to minor, in others, is believed to be exotic, i.e., of circumstellar or interstellar origin, and it is upon such material that researchers focus here. The nature of the meteoritic samples and the techniques used to analyse them are briefly discussed and the observational record is surveyed. Clearly, the study of exotic carbon preserved in meteorites has been informative about sites of nucleosynthesis, processes of nucleation and growth of grains in stellar outflows, grain survival in the interstellar medium, and many other topics of astrophysical significance. Much more work, particularly of an interdisciplinary nature remains to be done, however.

Kerridge, John F.

1990-04-01

344

Super Growth Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Water assisted CVD (denoted as Super Growth) results in a significant enhanced catalyst activity and enlonged lifetime of the catalysts to synthesize carbon nanotubes. The high efficient growth results in massive growth of vertically-aligned single-walled nanotubes forests with heights up to 2.5 millimeters and carbon purity over 99.98%. Super Growth simultaneously addresses many critical problems such as scalability, purity, and cost, and opens up innumerable opportunities ranging from fundamental research to real applications. This presentation will provide an overview of our recent development of the ``Super Growth'' CVD. First, the synthesis of highly efficient impurity free SNWT forest will be described. Second, the growth dynamics will be explored with our recent advance in CNT synthesis, as well as characterizing the physical and chemical properties of SWNT forests. Third, various new forms of carbon nanotube material such as DWNT forests, SWNT solids made by utilizing the super-growth technique will be demonstrated with emphasis on their applications such as super-capacitors. Lastly, challenges and future projects that are planed will be summarized.

Hata, Kenji

2006-03-01

345

Carbon nanotube mechanical resonators  

NASA Astrophysics Data System (ADS)

Nano-electromechanical systems (NEMS) make use of electrically induced mechanical motion and vice versa. Carbon nanotubes are ideal building blocks of NEMS because of their unique (mechanical) properties and their low mass. This puts them in an unexplored regime of motion which approaches the fundamental detection limit set by quantum mechanics. At room temperature, we use mixing techniques to probe the bending-mode vibration of a suspended carbon nanotube; the gate voltage strains the carbon nanotube and thereby tunes the frequency. At low temperatures, mechanical vibrations are actuated by a nearby antenna and a record high Q-value of 150000 at a resonance frequency of 300 MHz is achieved. Electron tunneling and mechanical motion are strongly coupled resulting in single- electron tuning oscillations of the mechanical frequency and in energy transfer to the electrons causing mechanical damping. Strikingly, we also observe that a d.c. current through the nanotube spontaneously drives the mechanical resonator, exerting a force that is synchronized with the high-frequency vibrations.

van der Zant, Herre

2010-03-01

346

Isotope composition of carbon in the carbonates of the Gumbeykan scheelite deposits in the southern Urals  

Microsoft Academic Search

Through investigations of the isotope composition of carbon of various generations and carbonates from marbles, skarns, and nested and vein scheelite orebodies, the probable source of carbon of these carbonates has been established as a mixture of sedimentary carbonates, carbon dioxide with carbonic acid that was formed by oxidation of the organic matter from sedimentary terrane (..delta..C¹³ - 0.05 to

A. F. Korzhinskiy; G. P. Mamchur; O. A. Yarynych

1980-01-01

347

Catalytic carbon deposition on three-dimensional carbon fiber preforms using alkane gas feedstocks  

Microsoft Academic Search

The rate of carbon deposition and the carbon nanostructures formed during the chemical vapor deposition of ethane and synthetic natural gas, with and without added hydrogen, over a nickel catalyst, supported on three-dimensional (3D) carbon fiber preforms, was investigated. Graphitic nanofibers, carbon nanotubes, and graphitic carbon shells were observed following carbon deposition; the nanostructured carbon deposited was dependant on deposition

Matthew J Thornton; Gavin S Walker

2009-01-01

348

Mass spectroscopic characterization of yttrium-containing metallofullerene YC82 using resonant laser ablation  

Microsoft Academic Search

In this paper, resonant laser ablation time-of-flight mass spectroscopy (RLA-TOF-MS) has been used to mass spectroscopic characterization of yttrium-containing fullerenes. Solvent soluble, yttrium-containing fullerenes are extracted from yttrium\\/carbon soot produced by the carbon-arc fullerene generation method. The RLA-TOF mass spectra indicate the presence of YC82. The metallofullerences YC60, YC70, Y2C82 and a series of Y2C2n are not observed by RLA-TOF-MS.

Shiliang Wang; Jiahe Tian; Songtao Dai; Dieyan Chen; Chuping Luo; Haisong Tan; Liangbing Gan; Chunhui Huang

1995-01-01

349

Mass spectroscopic characterization of yttrium-containing metallofullerene YC82 using resonant laser ablation  

SciTech Connect

In this paper, resonant laser ablation time-of-flight mass spectroscopy (RLA-TOF-MS) has been used to mass spectroscopic characterization of yttrium-containing fullerenes. Solvent soluble, yttrium-containing fullerenes are extracted from yttrium/carbon soot produced by the carbon-arc fullerene generation method. The RLA-TOF mass spectra indicate the presence of YC82. The metallofullerences YC60, YC70, Y2C82 and a series of Y2C2n are not observed by RLA-TOF-MS. This result is consistent with the ESR spectral result reported by Shinohara et al.

Wang Shiliang; Tian Jiahe; Dai Songtao; Chen Dieyan; Luo Chuping; Tan Haisong; Gan Liangbing; Huang Chunhui [Laser Single Atom Detection Laboratory, Department of Physics, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Rare Earth Material Chemistry and Applications, Peking University, Beijing 100871 (China)

1995-04-01

350

Carbon and graphite matrices in carbon-carbon composites: An overview of their formation, structure, and properties. Technical report  

Microsoft Academic Search

Carbon-carbon (C\\/C) composites, so called because they combine carbon-fiber reinforcement in an all-carbon matrix, can best be viewed as part of the broader category of carbon-fiber-based composites, all of which seek to utilize the light weight and exceptional strength and stiffness of carbon fibers. In C\\/C particularly, the structural benefits of carbon-fiber reinforcement are combined with the high-temperature capability of

Rellick

1992-01-01

351

Natural Carbonation of Peridotite and Applications for Carbon Storage  

NASA Astrophysics Data System (ADS)

Natural carbonation of peridotite in the Samail Ophiolite of Oman is surprisingly rapid and could be further enhanced to provide a safe, permanent method of CO2 storage through in situ formation of carbonate minerals. Carbonate veins form by low-temperature reaction between peridotite and groundwater in a shallow weathering horizon. Reaction with peridotite drives up the pH of the water, and extensive travertine terraces form where this groundwater emerges at the surface in alkaline springs. The potential sink for CO2 in peridotite is enormous: adding 1wt% CO2 to the peridotite in Oman could consume 1/4 of all atmospheric carbon, and several peridotite bodies of comparable size exist throughout the world. Thus carbonation rate and cost, not reservoir size, are the limiting factors on the usefulness of in situ mineral carbonation of peridotite for carbon storage. The carbonate veins in Oman are much younger than previously believed, yielding average 14C ages of 28,000 years. Age data plus estimated volumes of carbonate veins and terraces suggest 10,000 to 100,000 tons per year of CO2 are consumed by these peridotite weathering reactions in Oman. This rate can be enhanced by drilling, hydraulic fracture, injecting CO2-rich fluid, and increasing reaction temperature. Drilling and hydraulic fracture can increase volume of peridotite available for reaction. Additional fracture may occur due to the solid volume increase of the carbonation reaction, and field observations suggest that such reaction-assisted fracture may be responsible for hierarchical carbonate vein networks in peridotite. Natural carbonation of peridotite in Oman occurs at low pCO2, resulting in partial carbonation of peridotite, forming magnesite and serpentine. Raising pCO2 increases carbonation efficiency, forming of magnesite + talc, or at complete carbonation, magnesite + quartz, allowing 30wt% CO2 to be added to the peridotite. Increasing the temperature to 185C can improve the reaction rate by a factor of more than 100,000. Thermal modeling suggests that after an initial heating stage, CO2-rich fluids injected at relatively low temperature can be heated by exothermic carbonation reactions, offsetting diffusive heat loss to maintain optimal temperatures for rapid carbonation without additional energy input. With these enhancements, in situ carbonation could consume more than 1 billion tons of CO2 per cubic kilometer of peridotite per year. Costs associated with this method include drilling, hydraulic fracture, initial heating, CO2 capture and transport, fluid injection and monitoring. The techniques for drilling, fracture and injection are routinely used by oil companies. Compared with other carbon storage methods, in situ mineral carbonation has several advantages. It offers permanent storage that is safer and easier to monitor than storage of CO2-rich fluids in porous underground reservoirs or in the ocean. It may also be less costly than ex situ mineral carbonation, which requires quarrying and transportation of peridotite, grinding and heat treatment, reactions in pressure vessels at elevated temperature, production of catalysts, and disposal of carbonated material. An alternative method, carbonation by reaction of offshore peridotite with shallow seawater rather than CO2-rich fluids, would consume less CO2, but would avoid the costs of CO2 capture and transport inherent in other CCS methods. Drilling to depths where rocks are already close to the optimal carbonation temperature would avoid pre-heating costs and circulate water by thermal convection rather than pumping fluids.

Streit, E.; Kelemen, P.; Matter, J.

2009-05-01

352

A look at carbonate rocks  

SciTech Connect

Important ore deposits are found in carbonate rocks, and large volumes of oil and gas are also produced from carbonate rocks on a worldwide basis. Reservoir types and productive capability are most often related to rock type and the facies to which the rock belongs. Broad new understanding of carbonate rocks came with the publication of Classification of Carbonate Rocks-A Symposium (AAPG Memoir 1, 1962). The principal parameters of carbonate rocks are (1) chemical composition, (2) grade size, (3) sorting and packing, (4) identification of grains in the rock, (5) cement, (6) color, (7) alteration of recrystallization, and (8) porosity. Original porosity in carbonate rocks relates to kind and packing of original particles. Secondary porosity is reduced by infilling that usually relates to some particles, or is enhanced because some types of grains are dissolved. Carbonate sediments are organic detritus. The range of solubility of organic detritus is very large. Fossils present in the carbonates are clues as to the source of the detritus in the rock. Additional research is needed in faunal relations of facies and of rock types. Ore recovery, well completion, and EOR are more successful when the parameters of carbonate rocks are extensively studied. A simplified approach to carbonate description is discussed.

Bowsher, A.I. (Independent Geologist, Roswell, NM (United States))

1994-03-01

353

Uncovering the Neoproterozoic carbon cycle.  

PubMed

Interpretations of major climatic and biological events in Earth history are, in large part, derived from the stable carbon isotope records of carbonate rocks and sedimentary organic matter. Neoproterozoic carbonate records contain unusual and large negative isotopic anomalies within long periods (10-100 million years) characterized by ?(13)C in carbonate (?(13)C(carb)) enriched to more than +5 per mil. Classically, ?(13)C(carb) is interpreted as a metric of the relative fraction of carbon buried as organic matter in marine sediments, which can be linked to oxygen accumulation through the stoichiometry of primary production. If a change in the isotopic composition of marine dissolved inorganic carbon is responsible for these excursions, it is expected that records of ?(13)C(carb) and ?(13)C in organic carbon (?(13)C(org)) will covary, offset by the fractionation imparted by primary production. The documentation of several Neoproterozoic ?(13)C(carb) excursions that are decoupled from ?(13)C(org), however, indicates that other mechanisms may account for these excursions. Here we present ?(13)C data from Mongolia, northwest Canada and Namibia that capture multiple large-amplitude (over 10 per mil) negative carbon isotope anomalies, and use these data in a new quantitative mixing model to examine the behaviour of the Neoproterozoic carbon cycle. We find that carbonate and organic carbon isotope data from Mongolia and Canada are tightly coupled through multiple ?(13)C(carb) excursions, quantitatively ruling out previously suggested alternative explanations, such as diagenesis or the presence and terminal oxidation of a large marine dissolved organic carbon reservoir. Our data from Namibia, which do not record isotopic covariance, can be explained by simple mixing with a detrital flux of organic matter. We thus interpret ?(13)C(carb) anomalies as recording a primary perturbation to the surface carbon cycle. This interpretation requires the revisiting of models linking drastic isotope excursions to deep ocean oxygenation and the opening of environments capable of supporting animals. PMID:22388817

Johnston, D T; Macdonald, F A; Gill, B C; Hoffman, P F; Schrag, D P

2012-02-29

354

Biological Carbon Sequestration and Carbon Trading Re-Visited  

Microsoft Academic Search

Abstract Under Kyoto, biological activities that sequester carbon canbe used to create CO2offset credits that could obviate the need for lifestyle-changing reductions in fossil fuel use. Credits are earned by storing carbon in terrestrialecosystems and wood products, although CO2emissions are also mitigated by delaying deforestation, which accounts for one-quarter of anthropogenic CO2emissions. However, non-permanent carbon offsets from biological activities are

G. Cornelis van Kooten

2007-01-01

355

Hyperpolarized carbon-carbon intermolecular multiple quantum coherences  

NASA Astrophysics Data System (ADS)

Intermolecular multiple quantum coherences (iMQCs) can provide unique contrast with sub-voxel resolution. However, the characteristic growth rate of iMQCs mostly limits these effects to either hydrogen or hydrogen-coupled systems for thermally polarized samples. Hyperpolarization techniques such as dynamic nuclear polarization (DNP) allow for significant increases in the carbon signal (even more signal than that from hydrogen), making carbon iMQCs achievable. We present the first intermolecular multiple quantum signal between two carbon nuclei.

Jenista, Elizabeth R.; Branca, Rosa T.; Warren, Warren S.

2009-01-01

356

Biological carbon sequestration and carbon trading re-visited  

Microsoft Academic Search

Biological activities that sequester carbon create CO2 offset credits that could obviate the need for reductions in fossil fuel use. Credits are earned by storing carbon in terrestrial\\u000a ecosystems and wood products, although CO2 emissions are also mitigated by delaying deforestation, which accounts for one-quarter of anthropogenic CO2 emissions. However, non-permanent carbon offsets from biological activities are difficult to compare

G. Cornelis van Kooten

2009-01-01

357

Inhibition of catalytic oxidation of carbon\\/carbon composite materials  

Microsoft Academic Search

An investigation coupling experimental efforts with computational chemistry analysis was conducted to study the inhibition effects of phosphorous or boron on the oxidation of carbon\\/carbon composite materials catalyzed by potassium or calcium acetate (KAC or CaAC). Commercial aircraft brakes were used, which are exposed during use to K- or Ca-containing runway deicing agents. The reactivity of inhibitor-doped carbon materials was

Xianxian Wu

2002-01-01

358

Horizontally oriented carbon nanotubes coated with nanocrystalline carbon  

Microsoft Academic Search

Single-walled carbon nanotubes (CNTs) and multi-walled CNTs of length 25mm were grown from Fe\\/Mo nanoparticles and Fe thin film catalyst, respectively, by thermal chemical vapor deposition. Following CNT growth, the CNTs were in-situ coated with nanocrystalline carbon shells of thickness 1001500nm. Horizontally oriented CNTs with carbon shells in the direction of the feeding gas were visible under a regular optical

Neng-Kai Chang; Jung-Hui Hsu; Chih-Chung Su; Shuo-Hung Chang

2009-01-01

359

Model protocells photochemically reduce carbonate to organic carbon  

Microsoft Academic Search

Synthetic cell-sized organic microstructures effect the long-wavelength UV photosynthesis of organic products from carbonate. Formaldehyde is the most abundant photoproduct and water is the major proton donor for this reduced form of carbon. The apparent quantum yield is ~10-5 carbon atoms per incident UV 254-nm photon. We show here that these results for model phase-bounded systems are consistent with the

Clair Folsome; Andrew Brittain

1981-01-01

360

Alternative cathodes for molten carbonate fuel cells  

SciTech Connect

Yttrium Ions Garnets (YIG), Y{sub 3}Fe{sub 5}O{sub 12}, and Barium Ferrite, BaFe{sub 12}O{sub 19}, were synthesized and characterized. Among the various synthesis techniques tried the gel resin process was found to be the best method of synthesis in terms of purity of the phase and the conventional powder mixing/calcination technique was found to give the highest yield of the desired phase in larger quantities. Doping and calcining conditions were established to synthesize phase pure Ca-doped cubic YIG. The weight loss of doped YIG in molten carbonate was comparable to that reported for NiO, the current state-of-the-art cathode material. However, the stability of the YIG is expected to be better than NiO due to the stability of the corrosion product, Y{sub 2}O{sub 3}. The performance of doped YIG cathode in an in-cell test at the Institute of Gas Technology was below the present state of the are cathode due to high polarization loss. A Barium Ferrite based magnetoplumbite material was tested as a potential cathode candidate in molten carbonate. The material formed a reaction product that was conductive at room temperature; it also exhibited some magnetization.

Rolfson, B.K.; Elangovan, S.; Khandkar, A.C. (Ceramatec, Inc., Salt Lake City, UT (USA))

1990-05-01

361

Soil warming, carbon-nitrogen interactions, and forest carbon budgets  

PubMed Central

Soil warming has the potential to alter both soil and plant processes that affect carbon storage in forest ecosystems. We have quantified these effects in a large, long-term (7-y) soil-warming study in a deciduous forest in New England. Soil warming has resulted in carbon losses from the soil and stimulated carbon gains in the woody tissue of trees. The warming-enhanced decay of soil organic matter also released enough additional inorganic nitrogen into the soil solution to support the observed increases in plant carbon storage. Although soil warming has resulted in a cumulative net loss of carbon from a New England forest relative to a control area over the 7-y study, the annual net losses generally decreased over time as plant carbon storage increased. In the seventh year, warming-induced soil carbon losses were almost totally compensated for by plant carbon gains in response to warming. We attribute the plant gains primarily to warming-induced increases in nitrogen availability. This study underscores the importance of incorporating carbonnitrogen interactions in atmosphereoceanland earth system models to accurately simulate land feedbacks to the climate system.

Melillo, Jerry M.; Butler, Sarah; Johnson, Jennifer; Mohan, Jacqueline; Steudler, Paul; Lux, Heidi; Burrows, Elizabeth; Bowles, Francis; Smith, Rose; Scott, Lindsay; Vario, Chelsea; Hill, Troy; Burton, Andrew; Zhou, Yu-Mei; Tang, Jim

2011-01-01

362

Carbon-carbon heat pipe fabrication and CVD coating development  

NASA Astrophysics Data System (ADS)

A lightweight, high-performance, heat pipe radiator meeting SP-100 thermoelectric requirements has been identified. To facilitate the development and fabrication of this design, the resolution of two fundamental feasibility issues was required. First, it was necessary to produce a carbon-carbon heat pipe tube with integral fins meeting both thermal and mechanical requirements while satisfying structural weight goals. Second, it was necessary to develop a coating that protects the carbon-carbon substrate from the 875-K potassium working fluid. These feasibility issues have been resolved. Carbon-carbon tubes with integral fins were produced using a T-300 fiber, interlocking weave, and pitch densification. A barrier coating was then applied to the inside diameter of these tubes utilizing the chemical vapor deposition (CVD) of niobium over a thin rhenium interlayer. The rhenium interlayer was critical to the success of this coating by providing gradation in coefficient of thermal expansion (CTE) mismatch, carrying a portion of the induced stress load, improving coating adhesion, and providing a carbon diffusion barrier. Coatings with good adhesion to the interlayer and to the carbon-carbon body have been produced.

Rovang, R. D.; Dirling, R. B., Jr.; Holzl, R. A.

363

Geologic Carbon Sequestration and Biosequestration (Carbon Cycle 2.0)  

SciTech Connect

Don DePaolo, Director of LBNL's Earth Sciences Division, speaks at the Carbon Cycle 2.0 kick-off symposium Feb. 3, 2010. We emit more carbon into the atmosphere than natural processes are able to remove - an imbalance with negative consequences. Carbon Cycle 2.0 is a Berkeley Lab initiative to provide the science needed to restore this balance by integrating the Labs diverse research activities and delivering creative solutions toward a carbon-neutral energy future. http://carboncycle2.lbl.gov/

DePaolo, Don (Director, LBNL Earth Sciences Division)

2010-02-03

364

Novel carbon-carbon bond formations for biocatalysis  

PubMed Central

Carboncarbon bond formation is the key transformation in organic synthesis to set up the carbon backbone of organic molecules. However, only a limited number of enzymatic CC bond forming reactions have been applied in biocatalytic organic synthesis. Recently, further name reactions have been accomplished for the first time employing enzymes on a preparative scale, for instance the Stetter and PictetSpengler reaction or oxidative CC bond formation. Furthermore, novel enzymatic CC bond forming reactions have been identified like benzylation of aromatics, intermolecular Diels-Alder or reductive coupling of carbon monoxide.

Resch, Verena; Schrittwieser, Joerg H; Siirola, Elina; Kroutil, Wolfgang

2011-01-01

365

Carbon-hydrogen bonding in near-frictionless carbon  

SciTech Connect

The uniquely low friction behavior of near frictionless carbon (NFC) as compared to conventional diamond-like carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier Transform Infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface studies; the present results show that in the film as a whole the majority of the hydrogen is adjacent to sp3-bonded carbon. In addition this work has determined the absence of any molecular hydrogen in NFC.

Johnson, Jackie A. [University of Tennessee Space Institute; Woodford, John B [Argonne National Laboratory (ANL); Rajput, Deepak [University of Tennessee Space Institute; Kolesnikov, Alexander I [ORNL; Schleuter, John A [Argonne National Laboratory (ANL); Eryilmaz, Osman L [Argonne National Laboratory (ANL); Erdemir, Ali [Argonne National Laboratory (ANL)

2008-01-01

366

Carbon-hydrogen bonding in near-frictionless carbon.  

SciTech Connect

The uniquely low friction behavior of near-frictionless carbon (NFC) as compared to conventional diamondlike carbon (DLC) is determined by the bonding within the film. Inelastic neutron scattering (INS) and Fourier transform infrared (FTIR) spectroscopy were used to probe the bonding environment of carbon and hydrogen; both INS and FTIR can probe the whole sample. Previous work has focused on surface studies; the present results show that in the film as a whole the majority of the hydrogen is adjacent to sp{sup 3}-bonded carbon. In addition this work has determined the absence of any molecular hydrogen in NFC.

Johnson, J. A.; Woodford, J. B.; Rajput, D.; Kolesnikov, A. I.; Schleuter, J. A.; Eryilmaz, O. L.; Erdemir, A.; Univ. of Tennessee Space Inst.; ORNL

2008-01-01

367

Method for joining carbon-carbon composites to metals  

DOEpatents

A method for joining carbon-carbon composites to metals by brazing. Conventional brazing of recently developed carbon-bonded carbon fiber (CBCF) material to a metal substrate is limited by the tendency of the braze alloy to ``wick`` into the CBCF composite rather than to form a strong bond. The surface of the CBCF composite that is to be bonded is first sealed with a fairly dense carbonaceous layer achieved by any of several methods. The sealed surface is then brazed to the metal substrate by vacuum brazing with a Ti-Cu-Be alloy. 1 fig.

Lauf, R.J.; McMillan, A.D.; Moorhead, A.J.

1997-07-15

368

Compilation of carbon-14 data  

SciTech Connect

A review and critical analysis was made of the original sources of carbon-14 in the graphite moderator and reflector zones of the eight Hanford production reactors, the present physical and chemical state of the carbon-14, pathways (other than direct combustion) by which the carbon-14 could be released to the biosphere, and the maximum rate at which it might be released under circumstances which idealistically favor the release. Areas of uncertainty are noted and recommendations are made for obtaining additional data in three areas: (1) release rate of carbon-14 from irradiated graphite saturated with aerated water; (2) characterization of carbon-14 deposited outside the moderator and reflector zones; and (3) corrosion/release rate of carbon-14 from irradiated steel and aluminum alloys.

Paasch, R.A.

1985-07-08

369

Comparative study of heavy metal ions sorption onto activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles  

Microsoft Academic Search

The paper presents the advantages and limitations of heavy metals sorption onto three different carbon materials: activated carbon, carbon nanotubes, and carbon-encapsulated magnetic nanoparticles. Studied carbon sorbents differed with the grain size, crystallinity, and active surface area, which were derived from electron microscopy, Raman spectroscopy, and methylene blue adsorption, respectively. Detailed sorption studies were based on two model metal ions,

Krystyna Pyrzy?ska; Micha? Bystrzejewski

2010-01-01

370

Carbon and Graphite Matrices in Carbon-Carbon Composites: An Overview of their Formation, Structure, and Properties.  

National Technical Information Service (NTIS)

Carbon-carbon (C/C) composites, so called because they combine carbon-fiber reinforcement in an all-carbon matrix, can best be viewed as part of the broader category of carbon-fiber-based composites, all of which seek to utilize the light weight and excep...

G. S. Rellick

1992-01-01

371

Hydrogen uptake by carbon nanotubes  

Microsoft Academic Search

Multi-wall carbon nanotubes were synthesised from the catalytic decomposition of CO and CH4 on powder Co\\/La2O3 catalysts. TEM and HR-TEM, XRD, and TGA were used to characterise carbon nanotubes. It was found that by adjusting the composition of the catalysts, the size of the nanotubes was controllable and by annealing, the crystallinity could be improved. The carbon nanotubes produced from

X. B. Wu; P. Chen; J. Lin; K. L. Tan

2000-01-01

372

Lithium Diffusion in Graphitic Carbon  

Microsoft Academic Search

Graphitic carbon is currently considered the state-of-the-art material for the negative electrode in lithium-ion cells, mainly due to its high reversibility and low operating potential. However, carbon anodes exhibit mediocre charge\\/discharge rate performance, which contributes to severe transport-induced surface-structural damage upon prolonged cycling, and limits the lifetime of the cell. Lithium bulk diffusion in graphitic carbon is not yet completely

Kristin Persson; Vijay A. Sethuraman; Laurence J. Hardwick; Yoyo Hinuma; Ying Shirley Meng; Anton van der Ven; Venkat Srinivasan; Robert Kostecki; Gerbrand Ceder

2011-01-01

373

Activated carbon from municipal waste  

Microsoft Academic Search

A refuse derived fuel (RDF) was carbonized by partial combustion at 623 K and the carbonized RDF (cRDF) was steam-activated at 1123 K. The cRDF was also treated by 3.3 or 5.2 N nitric acid at a boiling temperature for 3 h prior to the steam-activation. Porous properties of the activated carbons prepared were determined by the nitrogen adsorption method.

S Nagano; H Tamon; T Adzumi; K Nakagawa; T Suzuki

2000-01-01

374

Raman Scattering in Carbon Nanotubes  

Microsoft Academic Search

The vibrational properties of single-walled carbon nanotubes reflect the electron and phonon confinement as well as the cylindrical\\u000a geometry of the tubes. Raman scattering is one of the prime techniques for studying the fundamental properties of carbon tubes\\u000a and nanotube characterization. The most important phonon for sample characterization is the radial-breathing mode, an in-phase\\u000a radial movement of all carbon atoms.

Christian Thomsen; Stephanie Reich

375

Carbon monoxide in foundry air.  

PubMed

The concentration of carbon monoxide in the air of 67 iron, steel, or copper alloy foundries using sand molding was measured. About 1,100 carbon monoxide determinations were made. High concentrations of carbon monoxide were found in the area around the cupolas and the casting sites in iron foundries. The blood carboxyhemoglobin levels of 145 workers from iron foundries were measured. The carboxyhemoglobin level of 6% was exceeded in 26% of the nonsmokers and in 71% of the smokers. PMID:968463

Virtamo, M; Tossavainen, A

1976-01-01

376

Chiral recognition of carbon nanoforms.  

PubMed

The selective recognition of chiral carbon nanoforms poses a fundamental challenge. New design principles must be devised to construct hosts capable of enantiodiscrimination between species in which chirality does not arise from asymmetric carbon atoms. In this emerging area article, we provide an overview of some of the relatively few successful examples of chiral recognition of carbon nanoforms, highlighting their common features with the aim of helping to develop general trends for the design of new generations of hosts. PMID:22391761

Prez, Emilio M; Martn, Nazario

2012-03-05

377

Carbon-Nanotube Metrology  

Microsoft Academic Search

\\u000a Scientific and industrial metrology provided tools for technological growth and\\u000a innovation, by fostering competitiveness and creating a favorable environment for\\u000a scientific and industrial development. Every major country has its own metrology\\u000a institute to support companies in increasing their productivity and the quality of\\u000a their goods and services. The fast development of carbon-nanotube science and\\u000a applications urged studies on metrology, standardization

Ado Jorio; Esko Kauppinen; Abdou Hassanien

378

Filling carbon nanotubes  

NASA Astrophysics Data System (ADS)

Filling hollow carbon nanotubes with chosen materials opens new possibilities of generating nearly one-dimensional nanostrutures. One simple approach to fill nanotubes is to use capillarity forces. Here, we have studied the wetting and capillarity by metal salts. First, nanotubes were opened by oxidation in air; subsequently, nanotubes were immersed in molten salts. We have observed a size-dependence filling indicating a lowering of the cavity-salt interface energy with decreasing diameter. By expressing the wetting conditions as a function of polarizabilities, it is possible to predict the threshold diameter for capillary filling of different materials.

Ugarte, D.; Stckli, T.; Bonard, J. M.; Chtelain, A.; de Heer, W. A.

379

Integrated Carbon Observation System  

NASA Astrophysics Data System (ADS)

ICOS is a recently-launched, world-class research infrastructure dedicated to the monitoring and improved understanding of carbon sources and sinks. It consists of complementary, harmonized networks of long-term monitoring stations focusing on Europe and adjacent regions. The ICOS networks will comprise about 40 operational atmospheric stations (measuring atmospheric composition in greenhouse gases and other core parameters), ca. 30 ecosystem stations (measuring fluxes to and from ecosystems) and about 25 oceanic measurement platforms (including fixed time series stations, repeat hydrographic sections and voluntary observing ships). The station networks are expected to be operational in 2014. The networks will be coordinated through a set of central facilities: three Thematic Centres respectively for atmospheric, ecosystem and ocean data, and a Central Analytical Laboratory. The mission of the Thematic Centres is to process, validate and distribute data to end-users. ICOS will also set up a Carbon Portal dedicated to easy discovery of and access to data and elaborated products such as flux maps by end users. Through its Preparatory Phase Project (funded by the EU through FP7) ICOS is currently demonstrating its capability to monitor greenhouse gases across Europe at four atmospheric sites and four ecosystem sites, working in near real time with the Atmospheric and Ecosystem Thematic Centres. At this occasion, the instrumental packages, the experimental set up as well as protocols prepared for the standardized ICOS stations are tested. ICOS atmospheric measurements, in combination with a dedicated modelling framework, will allow estimating daily fluxes at a typical resolution of 50 km with a precision of ~40 gC m-2 yr-1. The ecosystem network informs on the small scale variability of fluxes and its drivers. When completed, ICOS will provide the essential long-term observations required to understand the present state and predict future behaviour of the global carbon cycle and greenhouse gases emissions. ICOS will notably provide key data for the monitoring and assessment of the impact of carbon sequestration and/or greenhouse gases emission reduction activities on global atmospheric composition levels.

Paris, J.-D.; Ciais, P.; Rivier, L.; Chevallier, F.; Dolman, H.; Flaud, J.-M.; Garrec, C.; Gerbig, C.; Grace, J.; Huertas, E.; Johannessen, T.; Jordan, A.; Levin, I.; Papale, D.; Valentini, R.; Watson, A.; Vesala, T.; ICOS-PP Consortium

2012-04-01

380

Ultrahigh Carbon Steels  

NASA Astrophysics Data System (ADS)

Recent studies and results on ultrahigh carbon (UHC) steels suggest that major development efforts on these steels are timely and that programs to evaluate prototype structural components should be initiated. These recent results include: the development of economical processing techniques incorporating a divorced eutectoid transformation, the improvement of room temperature strength and ductility by heat treatment, the enhancement of superplastic properties through dilute alloying with silicon, and the attainment of exceptional notch impact strength in laminated UHC steel composites manufactured through solid state bonding. The unique mechanical properties achieved in UHC steels are due to the presence of micron-size fer-rite grains and ultrafine spheroidized carbides.

Sherby, O. D.; Oyama, T.; Kum, D. W.; Walser, B.; Wadsworth, J.

1985-06-01

381

Microderivatization of anodized glassy carbon.  

PubMed

Microelectrodes have been used to modify locally the electrochemical activity on glassy carbon electrodes. Glassy carbon was electrochemically oxidized to form an oxide layer which is inhibitory toward certain electron-transfer reactions. Activity was restored through the application of hydroxide, which was generated electrochemically at the tip of a microelectrode. With the tip positioned in close proximity to the anodized glassy carbon surface, microdomains of electrochemical activity were created in an otherwise inactive matrix. The distribution of electrochemical activity was characterized using electrochemical feedback at the microelectrode, electrogenerated chemiluminescence imaging, and electrodeposition of silver. Spatially directed activation of the glassy carbon surface was accomplished in the micrometer domain. PMID:21619289

Ratcliff, B B; Klancke, J W; Koppang, M D; Engstrom, R C

1996-07-01

382

Carbon-assisted flyer plates  

DOEpatents

A laser driven flyer plate utilizing an optical fiber connected to a laser. The end of the optical fiber has a layer of carbon and a metal layer deposited onto it. The carbon layer provides the laser induced plasma which is superior to the plasma produced from most metals. The carbon layer plasma is capable of providing a flatter flyer plate, converting more of the laser energy to driving plasma, promoting a higher flyer plate acceleration, and providing a more uniform pulse behind the plate. In another embodiment, the laser is in optical communication with a substrate onto which a layer of carbon and a layer of metal have been deposited.

Stahl, David B. (Los Alamos, NM); Paisley, Dennis L. (Santa Fe, NM)

1994-01-01

383

Organic electrochemistry and carbon electrodes  

SciTech Connect

Carbons are often used in organic electrosynthesis and are critical as anodes or cathodes to certain reactions. Too often the surface properties of carbons have been left uncharacterized in relation to the reaction; however, these physical and chemical properties of carbons are important to the nature of the products, and the selectivity. Examples presented include the Kolbe reaction, the oxidation of aromatics in presence of carboxylate salts, electrofluorination of organics, acetamidation of aromatics, the hydrodimerization of formaldehyde and the oxidation of carbon fibers. These reactions apparently involve special surface characteristics: structure, surface area, stabilized surface sites, and the presence or absence of significant ''oxide'' functionality

Weinberg, N.

1983-08-01

384

Energy Equals Managing Carbon Cleanly  

NASA Astrophysics Data System (ADS)

Almost 40 years after receiving a Ph.D. in physics, I am still working on problems where conservation laws matter. In particular, for the problems I work on now, the conservation of the carbon atom matters. I will tell the saga of an annual flow of 6 billion tons of carbon associated with the global extraction of fossil fuels from underground. Until recently, it was taken for granted that virtually all of this carbon will move within weeks through engines of various kinds and then into the atmosphere. For compelling environmental reasons, I and many others are challenging this complacent view, asking whether the carbon might wisely be directed elsewhere.

Socolow, Robert

2003-04-01

385

Carbon nanotube IR detectors (SV)  

SciTech Connect

Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

Leonard, F. L.

2012-03-01

386

Spectrophotofluorometric determination of terbium and europium in potassium carbonate solution.  

PubMed

The conditions for the spectrophotofluorometric determination of terbium and europium, in solutions of potassium carbonate, have been established. The apparent excitation and fluorescence wavelengths used, respectively, are 245 mmu and 550 mmu for terbium and 400 mmu and 620 mmu for europium. The fluorescence varies linearly with the concentration of terbium and europium in the range 0.3-70 mug, of terbium/ml and 4-800 mug of europium/ml. Large amounts of gadolinium, lutetium and yttrium do not interfere. Cerium(IV) interferes seriously. PMID:18959977

Taketatsu, T; Carey, M A; Banks, C V

1966-08-01

387

Carbon dioxide and climate  

SciTech Connect

Scientific and public interest in greenhouse gases, climate warming, and global change virtually exploded in 1988. The Department's focused research on atmospheric CO{sub 2} contributed sound and timely scientific information to the many questions produced by the groundswell of interest and concern. Research projects summarized in this document provided the data base that made timely responses possible, and the contributions from participating scientists are genuinely appreciated. In the past year, the core CO{sub 2} research has continued to improve the scientific knowledge needed to project future atmospheric CO{sub 2} concentrations, to estimate climate sensitivity, and to assess the responses of vegetation to rising concentrations of CO{sub 2} and to climate change. The Carbon Dioxide Research Program's goal is to develop sound scientific information for policy formulation and governmental action in response to changes of atmospheric CO{sub 2}. The Program Summary describes projects funded by the Carbon Dioxide Research Program during FY 1990 and gives a brief overview of objectives, organization, and accomplishments.

Not Available

1990-10-01

388

Carbon nanotube array actuators  

NASA Astrophysics Data System (ADS)

Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 7502000 ?m with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 ?m and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs.

Geier, S.; Mahrholz, T.; Wierach, P.; Sinapius, M.

2013-09-01

389

Chlorination of carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report ab initio density functional theory calculations for chlorinated single-wall carbon nanotubes and investigate the atomic structure, energetics, and electronic structure of the chlorinated nanotubes, as well as the energetics of the desorption reaction. We find that the Cl atoms should be adsorbed in pairs and thus focus on doubly chlorinated nanotubes. Using the terminology of arene substitution patterns, ortho and para configurations are the most stable. The physisorption is preferable to the chemisorption in large-diameter nanotubes. The impurity states appear near the Fermi level EF in the electronic structure and may alter the electronic properties considerably. The bonding character for adsorption outside the nanotube is mainly covalent, but inside it consists of physical bonding. The adsorption of several Cl atoms inside a carbon nanotube leads to the formation of a charged Cl chain. Our calculated desorption barrier of ?1.4 eV per Cl atom pair indicates that the cleansing by chlorination is a less damaging alternative with removable residue.

Erbahar, Dogan; Berber, Savas

2012-02-01

390

[Carbon monoxide poisoning].  

PubMed

Carbon monoxide (CO) is a product of incomplete burning of coals and carbon compounds and is a gas without any typical taste, colour or smell. Defective radiators or gas pipes, open fireplaces, fires and explosions are sources of unintended CO production and inhalation. CO bonds with haemoglobin much more readily than oxygen does. CO toxicity causes impaired oxygen delivery and utilisation at cellular level. It affects different sites within the body, but has its most profound impact on the organs with the highest oxygen requirement. CO concentration and the intensity and duration of inhalation determine the extent of intoxication. Following basic life support, assisted or controlled ventilation with 100% oxygen is essential during emergency care. Hyperbaric oxygenation (HBO) is the preferred therapeutic option for releasing CO from its binding to haemoglobin. It has been shown that CO may cause lipid peroxidation and leukocyte-mediated inflammatory changes in the brain, a process that may be inhibited by HBO. Patients with neurological symptoms including loss of consciousness and expectant mothers should undergo HBO treatment, no matter how high their CO levels are. Neonates and in-utero fetuses are more vulnerable due to the natural leftward shift of the dissociation curve of fetal haemoglobin, a lower baseline pO2 and carboxyhaemoglobin levels at equilibration that are 10-15% higher than maternal levels. Physicians need to be aware of the potential occurrence of this life threatening hazard so that appropriate emergency treatment can be administered and fatalities prevented. PMID:10920484

Jaeger, K; Ruschulte, H; Heine, J; Piepenbrock, S

2000-01-01

391

Carbon aerogels and xerogels  

SciTech Connect

The aqueous polycondensation of resorcinol with formaldehyde proceeds through a sol-gel transition and results in the formation of highly crosslinked, transparent gels. If the solvent is simply evaporated from the pores of these gels, large capillary forces are exerted and a collapsed structure known as a xerogel is formed. In order to preserve the gel skeleton and minimize shrinkage, the aforementioned solvent or its substitute must be removed under supercritical conditions. The microporous material that results from this operation is known as an aerogel. Because resorcinol-formaldehyde aerogels and xerogels consist of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths. The resultant porous materials are black in color and no longer transparent, yet they retain the ultrafine cell size (< 50 nm), high surface area (600--800 m[sup 2]/g), and the interconnected particle morphology of their organic precursors. The thermal, acoustic, mechanical, and electrical properties of carbon aerogels/xerogels primarily depend upon polymerization conditions and pyrolysis temperature. In this paper, the chemistry-structure-property relationships of these unique materials will be discussed in detail.

Pekala, R.W.; Alviso, C.T.

1992-04-01

392

[Unusual carbon monoxide poisoning].  

PubMed

Despite of indicative death scenes or characteristic findings of the external examination, about 40% of the accidental fatal intoxications due to carbon monoxide are not recognized before the performance of the autopsy. Six cases are reported which illustrate possible reasons for the delayed establishment of the diagnosis: unusual circumstances of the intoxication or sources of carbon monoxide, only subtle degree or lack of external signs of the intoxication or a competing cause of death at autopsy.--Cases 1 and 2: 53, respectively 54-year-old couple, found dead in a caravan, extreme putrefaction of the bodies, spectrophotometric detection of the fatal carboxyhaemoglobin level in oedema fluid of the scalp.--Case 3: 23-year-old lorry driver, found dead in the tightly closed cab of his lorry, operation of a source of electricity with "environmentally friendly" fuel, carboxyhaemoglobin level 83%.--Case 4: 19-year-old man, found dead in the flat of friends, removal of the CO-source before alerting the police forces, lack of the bright pink coloration of livor mortis, haemopericardium due to atrial rupture at postmortem examination, carboxyhaemoglobin level 65%.--Case 5: 27-year-old man, found dead in his flat, advanced decomposition of the body, residues of a charcoal fire in a metal bucket in the sink, carboxyhaemoglobin level 80%.--Case 6: 42-year-old woman, lying dead in the garage beside her car, engine switched-off, ignition key next to the body on the floor under the car, carboxyhaemoglobin level 46%. PMID:11591055

Schmidt, P; Musshoff, F; Dettmeyer, R; Madea, B

393

Nanofabrication of carbon materials  

NASA Astrophysics Data System (ADS)

We demonstrate a process for fabrication of nanostructures on the surfaces of highly oriented pyrolytic graphite (HOPG) and glassy carbon (GC) samples. Using hole-mask colloidal lithography (HCL), nanosized etch masks with three different feature diameters were prepared by identical processes on each of the two surface types. Oxygen reactive ion etching (RIE) was then used to transfer the mask pattern onto the surfaces. The structures were characterized using atomic force- (AFM), scanning electron microscopy (SEM) and optical spectrophotometry. The identical preparation schemes applied to the two materials yield structures with remarkably different shape and sizes. For example the process that yields 361 nm high and 37 nm diameter structures on glassy carbon yields 120 nm high and 119 nm diameter structures on HOPG. In general, the diameters of the fabricated GC nano-features are always at least 80 nm smaller than those of the corresponding HOPG structures, and the GC structure heights are more than three times that of the HOPG structures. These differences are attributed to different (an)isotropic etching behavior of the two materials.

Chakarov, Dinko; Fredriksson, Hans; Kasemo, Bengt

2008-03-01

394

Biophilic carbon nanotubes.  

PubMed

Carbon nanotubes (CNTs) have been proposed and are actively being explored as innovative multipurpose carriers for biomolecules and diagnostic applications. Their versatile physico-chemical features enable them as a carrier of several pharmaceutically relevant entities and allow them for rational design of novel nanoscale candidates for drug development. Functionalized carbon nanotubes (f-CNT) are emerging as a new family of nanovectors for the delivery of different types of therapeutic molecules. The application of CNTs in the field of carrier-mediated delivery has become possible after the recent discovery of their capacity to penetrate into the cells. CNT can be loaded with active molecules by forming stable covalent bonds or supramolecular assemblies based on noncovalent interactions. Once the cargos are carried into various cells, tissues and organs they are able to express their biological function. In this review, we will describe the potential of f-CNT as a vehicle to deliver different types of therapeutic agents into the biological species. PMID:23384693

Mallick, Kaushik; Strydom, Andr M

2013-01-14

395

Properties of Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Different synthesizing methods are used to create various nanostructures of carbon; we are mainly interested in single and multi-wall carbon nanotubes, (SWCNTs) and (MWCNTs) respectively. The properties of these tubes are related to their synthetic methods, chirality, and diameter. The extremely sturdy structure of CNTs, with their distinct thermal and electromagnetic properties, suggests a tremendous use of these tubes in electronics and medicines. Here, we analyze various physical properties of SWCNTs with a special emphasis on electromagnetic and chemical properties. By examining their electrical properties, we demonstrate the viability of discrete CNT based components. After considering the advantages of using CNTs over microstructures, we make a case for the advancement and development of nanostructures based electronics. As for current CNT applications, it's hard to overlook their use and functionality in the development of cancer treatment. Whether the tubes are involved in chemotherapeutic drug delivery, molecular imaging and targeting, or photodynamic therapy, we show that the remarkable properties of SWCNTs can be used in advantageous ways by many different industries.

Masood, Samina; Bullmore, Daniel; Duran, Michael; Jacobs, Michael

2012-10-01

396

Carbon nanotube computer.  

PubMed

The miniaturization of electronic devices has been the principal driving force behind the semiconductor industry, and has brought about major improvements in computational power and energy efficiency. Although advances with silicon-based electronics continue to be made, alternative technologies are being explored. Digital circuits based on transistors fabricated from carbon nanotubes (CNTs) have the potential to outperform silicon by improving the energy-delay product, a metric of energy efficiency, by more than an order of magnitude. Hence, CNTs are an exciting complement to existing semiconductor technologies. Owing to substantial fundamental imperfections inherent in CNTs, however, only very basic circuit blocks have been demonstrated. Here we show how these imperfections can be overcome, and demonstrate the first computer built entirely using CNT-based transistors. The CNT computer runs an operating system that is capable of multitasking: as a demonstration, we perform counting and integer-sorting simultaneously. In addition, we implement 20 different instructions from the commercial MIPS instruction set to demonstrate the generality of our CNT computer. This experimental demonstration is the most complex carbon-based electronic system yet realized. It is a considerable advance because CNTs are prominent among a variety of emerging technologies that are being considered for the next generation of highly energy-efficient electronic systems. PMID:24067711

Shulaker, Max M; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H-S Philip; Mitra, Subhasish

2013-09-26

397

Introduction to Carbonate Equilibrium  

NSDL National Science Digital Library

The activity asks students to make observations about what occurs when two effervescent antacid tablets are placed into a beaker of water. The Students work together in groups. There are three parts to the activity. In the first part, the tablets are dropped into tap water and student groups (2-4 students) must complete a series of question sheets (one per group) that guide them through thinking about the event. In the second part, a presentation on chemical equilibrium for the carbonate system is given. The starting point is the answers received in the first part. Basic chemical reactions for the carbonate system are presented including equilibrium expressions for each reaction and discussion about open and closed systems. At the end of class, a handout is given to the students. In the third part, three beakers (acidic, neutral and basic solutions, but not indicated) are placed together and two tablets are placed into each beaker. Students are split into two groups (8-12 students) and are asked to describe why the reactions are different. Discussion follows collection of student responses in each part. Once the chemical reactions and equilibrium expressions are presented, they are involved and referenced in all discussions.

Stapleton, Michael

398

Understanding and managing the global carbon cycle  

Microsoft Academic Search

Summary 1 Biological carbon sinks develop in mature ecosystems that have high carbon storage when these systems are stimulated to increase productivity, so that carbon gains by photosynthesis run ahead of carbon losses by heterotrophic respiration, and the stocks of carbon therefore increase. This stimulation may occur through elevated CO 2 con- centration, nitrogen deposition or by changes in climate.

John Grace

2004-01-01

399

Advanced solar collector concepts using carbon  

Microsoft Academic Search

The chemical inertness of carbon, its black color, good thermal conductivity, and fabricability into a variety of physical forms makes it attractive as a material of construction for a family of unique and advanced second-generation solar collectors. Several carbon-based solar collector heat transport conceptual systems are described using carbon microspheroids, carbon pile fibers and whiskers, and reticulated (open pore) carbon

O. C. Baldonado; C. R. Schmitt

1981-01-01

400

Biological overprint of the geological carbon cycle  

Microsoft Academic Search

The oxidation of Earth's atmosphere is coupled to the net sequestration of organic matter, which is related to the relative fractions of organic carbon (forg) and carbonate (fcarb) buried in marine sediments. These fractions can be inferred from carbon isotope data. We present bulk sediment ?13C records of carbonate (?13Ccarb) and organic carbon (?13Corg) with a compilation of evolutionary trajectories

Miriam E. Katz; James D. Wright; Kenneth G. Miller; Benjamin S. Cramer; Katja Fennel; Paul G. Falkowski

2005-01-01

401

The Effects of Grazing Management on Soil Carbon (Carbon Sequestration)  

Microsoft Academic Search

This component of the VA RLEP consists of a field based sampling and research effort to document the efficacy of Management intensive Grazing (MiG) techniques to enhance the soil's inherent capacity to serve as a sink for carbon (four data collection sites were developed in VA). To the extent that MiG and associated conservation practices increase the storage of carbon

Richard T. Conant; Keith Paustian

402

Basic Solutions to Carbon/Carbon Oxidation: Science and Technology.  

National Technical Information Service (NTIS)

The goal of this study was to gain a fundamental understanding of the role of boron in carbon oxidation. Boron-doped carbons were synthesized via CVD, ion implantation and high temperature doping are subsequently characterized. It was found that high temp...

C. Pantano I. R. Harrison L. Radovic P. Thrower T. Chung

1998-01-01

403

Oxidation Microstructure Studies of Reinforced Carbon/Carbon.  

National Technical Information Service (NTIS)

Laboratory oxidation studies of reinforced carbon/carbon (RCC) are discussed with particular emphasis on the resulting microstructures. This study involves laboratory furnace (500-1500 C deg) and arc-jet exposures (1538 C deg) on various forms of RCC. RCC...

N. S. Jacobson D. M. Curry

2006-01-01

404

Policing carbon: design and enforcement options for personal carbon trading  

Microsoft Academic Search

Different approaches have been suggested for extending the reach of carbon trading into the whole economy by including the emissions resulting from individual consumption of energy. The most radical suggestions involve granting emissions rights to individualsknown as personal carbon trading (PCT). A taxonomy is provided of various proposed design options along with consideration of the previously neglected issue of who

NICK EYRE

2010-01-01

405

Fatigue Characterization of Functionalized Carbon Nanotube Reinforced Carbon Fiber Composites.  

National Technical Information Service (NTIS)

The primary purpose of this analytical report is to compare tension- tension fatiguing of a carbon fiber composite to tension-compression fatiguing. Although carbon fiber composites hold up well in tension-tension fatiguing, there is little knowledge of t...

D. Ayewah D. Davis J. Wilkerson

2007-01-01

406

Carbon dioxide sequestration in cement kiln dust through mineral carbonation  

SciTech Connect

Carbon sequestration through the formation of carbonates is a potential means to reduce CO{sub 2} emissions. Alkaline industrial solid wastes typically have high mass fractions of reactive oxides that may not require preprocessing, making them an attractive source material for mineral carbonation. The degree of mineral carbonation achievable in cement kiln dust (CKD) under ambient temperatures and pressures was examined through a series of batch and column experiments. The overall extent and potential mechanisms and rate behavior of the carbonation process were assessed through a complementary set of analytical and empirical methods, including mass change, thermal analysis, and X-ray diffraction. The carbonation reactions were carried out primarily through the reaction of CO{sub 2} with Ca(OH){sub 2}, and CaCO{sub 3} was observed as the predominant carbonation product. A sequestration extent of over 60% was observed within 8 h of reaction without any modifications to the waste. Sequestration appears to follow unreacted core model theory where reaction kinetics are controlled by a first-order rate constant at early times; however, as carbonation progresses, the kinetics of the reaction are attenuated by the extent of the reaction due to diffusion control, with the extent of conversion never reaching completion. 35 refs., 3 figs., 1 tab.

Deborah N. Huntzinger; John S. Gierke; S. Komar Kawatra; Timothy C. Eisele; Lawrence L. Sutter [University of Michigan, Ann Arbor, MI (United States). Department of Civil and Environmental Engineering

2009-03-15

407

Evaluation of Kerma in Carbon and the Carbon Cross Sections.  

National Technical Information Service (NTIS)

A preliminary simultaneous least squares fit to measurements of kerma in carbon, and carbon cross sections taken from the ENDF/B-V file was carried out. In the calculation the shapes of the total cross section and the various partial cross sections were r...

E. J. Axton

1992-01-01

408

Stuffing Carbon Away: Mechanisms of Carbon Sequestration in Soils  

Microsoft Academic Search

Soils offer the potential to sequester large quantities of carbon from the atmosphere for decades to millennia and so may ameliorate the anthropogenic influence of fossil fuel release. However changes in climate can drastically affect the soil's ability to store carbon through changes mineralogy on time scales of human interest. It is essential to understand the major controls on soil

P J Reimer; C A Masiello; J R Southon; S E Trumbore; J W Harden; A F White; O A Chadwick; M S Torn

2003-01-01

409

Chemical vapor deposition of pyrolytic carbon on carbon nanotubes  

Microsoft Academic Search

The chemical vapor deposition of the pyrocarbon from a CH4+H2 mixture is investigated using nanofilamentous substrates. The process consists of growing carbon nanotubes via a catalytic process, which then are thickened by pyrolytic carbon deposition to reach diameters in the nanometer to micrometer range. A key characteristic of the experimental reactor used was the long length of its isothermal zone,

Hatem Allouche; Marc Monthioux; Ronald L Jacobsen

2003-01-01

410

Carbon dioxide sequestration in cement kiln dust through mineral carbonation.  

PubMed

Carbon sequestration through the formation of carbonates is a potential means to reduce CO2 emissions. Alkaline industrial solid wastes typically have high mass fractions of reactive oxides that may not require preprocessing, making them an attractive source material for mineral carbonation The degree of mineral carbonation achievable in cement kiln dust (CKD) underambienttemperatures and pressures was examined through a series of batch and column experiments. The overall extent and potential mechanisms and rate behavior of the carbonation process were assessed through a complementary set of analytical and empirical methods, including mass change, thermal analysis, and X-ray diffraction. The carbonation reactions were carried out primarily through the reaction of CO2 with Ca(OH)2, and CaCO3 was observed as the predominant carbonation product. A sequestration extent of over 60% was observed within 8 h of reaction without any modifications to the waste. Sequestration appears to follow unreacted core model theory where reaction kinetics are controlled by a first-order rate constant at early times; however, as carbonation progresses, the kinetics of the reaction are attenuated by the extent of the reaction due to diffusion control, with the extent of conversion never reaching completion. PMID:19368202

Huntzinger, Deborah N; Gierke, John S; Kawatra, S Komar; Eisele, Timothy C; Sutter, Lawrence L

2009-03-15

411

Inhibited Carbon-Carbon Composites: Isothermal and Fatigue Exposure  

Microsoft Academic Search

The oxidation process is examined under isothermal, cyclic thermal and thermomechanical fatigue conditions for inhibited carbon-carbon composites. Mass loss and material property degradation assessment is undertaken with subsequent exploratory nondestructive testing utilizing DMA and PUCOT techniques. An analytical diffusion model is developed to evaluate oxidation degradation for selected exposure conditions. The results are then compared with the experimental data generated.

Ozden O. Ochoa; Charles H. Elliott

1998-01-01

412

Role of activated carbon pellets in carbon dioxide removal  

Microsoft Academic Search

The removal of carbon dioxide from gas\\/air streams is more often becoming necessary in many industries for different purposes. In cryogenic air separation plant, air has to be free from carbon dioxide before its liquefaction otherwise blockage due to freezing of heat exchange equipment would result. Enrichment of methane in biogas to have fuel of higher calorific value can be

S. C Sarkar; A Bose

1997-01-01

413

Three-dimensional helical carbon materials: Microcoiled carbon fibers, carbon nanocoils, carbon nanotubes: Synthesis, properties and applications  

NASA Astrophysics Data System (ADS)

Materials with a 3D-helical/spiral-structure in micron size have recently aroused a great deal of interests because of their helical morphology and unique properties. However, materials with a 3D helical structure are not commonly observed among industrially available materials. Researchers have been trying to synthesize various micro- and nano-sized 3D helical materials and are exploring the mechanisms, nature, and properties of these materials. Yet a systematic study on 3D helical carbon materials in micro- and nano-size has been missing. This research work is intended as a first step to fill this gap. Among various 3D helical materials, carbon element has stimulated great interests. Micro coiled carbon fibers, carbon nanocoils, and carbon nanotubes are major types of 3D helical carbon materials ranging from micron to nano size. Synthesis of these 3D helical carbon materials by a catalytic chemical vapor deposition method is presented in this thesis. It involves a pyrolysis of hydrocarbon gas (e.g. acetylene) over transition metals, such as Ni, Fe, and Co, at high reaction temperature (500--1000C). Besides the conventional thermal filament chemical vapor deposition method, a novel microwave chemical vapor deposition (MWCVD) method has been developed to synthesize micro- and nano-sized 3D helical carbon materials economically. The faster heating and cooling processes associated with microwave CVD have potential for large-scale production in the near future. Compared with previously reported microwave plasma enhanced chemical vapor deposition (MWPECVD) method, this method does not require high vacuum and much higher deposition rate is another major advantage. It has been found in this work that microwave plays an important role on coil morphology formation for micro coiled carbon fibers and carbon nanocoils. The large temperature gradient around the catalytic particles could be the reason. Different reaction factors have been checked to optimize the deposition. Due to their extraordinary properties, carbon nanotubes have been expected to have wide applications. Efforts have been made on the synthesis of high quality carbon nanotubes economically in this work. A novel catalyst/catalyst support pair, iron/magnesium carbonate, has been developed for synthesis of multi-walled carbon nanotubes with high purity. The coil morphology is induced by insertion of pentagon-heptagon pairs into hexagonal network of nanotube wall periodically. Thorough purification of carbon nanotubes is always a concern before investigating their properties and potential applications. Impurities in raw carbon nanotube material have to be removed by chemical treatment. A couple of purification methods are presented in this work. Various techniques have been used to characterize these micro- and nano-3D materials, such as scanning electron microscopy (SEM), energy dispersive spectrum (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer Emmett-Teller (BET), thermal gravimetric analysis (TGA), etc. Growth mechanisms are proposed based on the experimental and characterization results. It is verified that the nonuniform carbon deposition rate on catalyst particles leads to the bending of the carbon fiber/tubule, and hence results in the coil morphology. To conclude, the research work reported here is a systematic study on synthesis, characterizations, and applications of micro- and nano-3D helical carbon materials, such as micro coiled carbon fibers, carbon nanocoils and carbon nanotubes. A few suggestions for future research directions are also listed.

Xie, Jining

414

Friction behaviors of carbon\\/carbon composites with different pyrolytic carbon textures  

Microsoft Academic Search

Friction and wear properties of carbon\\/carbon (C\\/C) composites with a smooth laminar (SL), a medium textured rough laminar (RL) and a high textured RL pyrolytic carbon texture were investigated with a home-made laboratory scale dynamometer to simulate airplane normal landing (NL), over landing (OL) and rejected take-off (RTO) conditions. The morphology of worn surfaces at different braking levels was observed

Xiang Xiong; Bai-yun Huang; Jiang-hong Li; Hui-juan Xu

2006-01-01

415

Carbon Dioxide Carbonates in the Earth;s Mantle: Implications to the Deep Carbon Cycle  

SciTech Connect

An increase in the ionic character in C-O bonds at high pressures and temperatures is shown by the chemical/phase transformation diagram of CO{sub 2}. The presence of carbonate carbon dioxide (i-CO{sub 2}) near the Earth's core-mantle boundary condition provides insights into both the deep carbon cycle and the transport of atmospheric CO{sub 2} to anhydrous silicates in the mantle and iron core.

Yoo, Choong-Shik; Sengupta, Amartya; Kim, Minseob (Princeton); (WSU)

2012-05-22

416

Stuffing Carbon Away: Mechanisms of Carbon Sequestration in Soils  

SciTech Connect

Soils offer the potential to sequester large quantities of carbon from the atmosphere for decades to millennia and so may ameliorate the anthropogenic influence of fossil fuel release. However changes in climate can drastically affect the soil's ability to store carbon through changes mineralogy on time scales of human interest. It is essential to understand the major controls on soil carbon dynamics before we attempt to manage sequestration to control atmospheric CO{sub 2} buildup. Models of the terrestrial carbon cycle often use clay content to parameterize soil carbon turnover. Evidence from volcanic soils suggests that soil mineralogy is a major control on a soil's ability to store carbon, because different types of minerals have widely varying abilities to physically and chemically isolate soil organic matter from decomposition, however volcanic soils represent only a small percentage of the earth's soils. The relationship between precipitation and soil carbon storage is also complex and poorly constrained. Significantly, precipitation changes predicted as a result of atmospheric CO{sub 2} doubling include increased rainfall throughout California. We utilized {sup 14}C, {delta}{sup 13}C, and the total organic carbon, iron, and aluminum contents to address the question of the importance of mineralogy and climate on carbon storage in soils formed on a globally representative parent material. The California coastal terraces, formed over the last 500 thousand years as a result of tectonic uplift and sea level change, provide a natural laboratory to examine the effect of mineralogy and climate on carbon storage. We have focused on two terraces sequences, one near Eureka and one near Santa Cruz. Within each set of terraces only soil mineral development varies; all other variables are constant (rainfall, plant systems, and soil parent material, and land management). Annual precipitation at Eureka is twice that at Santa Cruz, allowing us to examine its role in the transport of organic carbon to deeper horizons. The objective of the study is to improve the understanding of soil carbon storage and derive a set of proxies for organic carbon turnover for terrestrial carbon cycle models.

Reimer, P J; Masiello, C A; Southon, J R; Trumbore, S E; Harden, J W; White, A F; Chadwick, O A; Torn, M S

2003-01-24

417

Intermediate Temperature Carbon - Carbon Composite Structures. CRADA Final Report  

SciTech Connect

The objective of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC (the "Contractor") and Synterials, Inc. (the "Participant") was to demonstrate promising processing methods, which can lead to producing Carbon-Carbon Composites (CCC), with tensile and interlaminar properties comparable to those of organic matrix composites and environmental stability at 1200 F for long periods of time. The participant synthesized carbon-carbon composites with two different fiber coatings and three different matrices. Both parties evaluated the tensile and interlaminar properties of these materials and characterized the microstructure of the matrices and interfaces. It was found that fiber coatings of carbon and boron carbide provided the best environmental protection and resulted in composites with high tensile strength.

Lara-Curzio, Edgar [ORNL

2007-06-01

418

Particulate fluxes of carbonate and organic carbon in the ocean. Is the marine biological activity working as a sink of the atmospheric carbon?  

Microsoft Academic Search

The particulate fluxes of carbonate carbon and organic carbon observed in various oceans have been summarized in this paper and discussed with special reference to the fate of the atmospheric carbon dioxide. The organic carbon fluxes, which act as a sink of atmospheric carbon dioxide, are generally larger than the carbonate carbon fluxes working as a source, but are comparable

Shizuo Tsunogai; Shinichiro Noriki

1991-01-01

419

Engaging zwitterions in carbon-carbon and carbon-nitrogen bond-forming reactions: A promising synthetic strategy.  

PubMed

An Account of carbon-carbon and carbon-nitrogen bond-forming reactions mediated by zwitterions generated by the addition of organic nucleophiles to activated unsaturated systems highlighting their synthetic potential is presented. PMID:16906748

Nair, Vijay; Menon, Rajeev S; Sreekanth, A R; Abhilash, N; Biju, A T

2006-08-01

420

Mass-Spectrometric Study of the Yttrium-Carbon System.  

National Technical Information Service (NTIS)

A high-temperature investigation of the vapor in thermodynamic equilibrium with Y-C condensed system was carried out in the temperature range 2075-2340K. Y and YC2 are shown to be important species in the vapor phase. Utilizing the pressure-independent re...

G. De Maria M. Guido L. Malaspina B. Pesce

1965-01-01

421

Mass Spectrometric Study of the Yttrium-Carbon System.  

National Technical Information Service (NTIS)

A high temperature investigation of the vapor in thermodynamic equilibrium with the Y-C condensed system was carried out in the temperature range 2075-2340 K. Y and YC2 are shown to be important species in the vapor phase. Utilizing the pressure independe...

G. De Maria M. Guido L. Malaspina B. Pesce

1965-01-01

422

Mass-Spectrometric Study of the Yttrium-Carbon System  

Microsoft Academic Search

A high-temperature investigation of the vapor in thermodynamic equilibrium with Y&sngbnd;C condensed system was carried out in the temperature range 20752340K. Y and YC2 are shown to be important species in the vapor phase. Utilizing the pressure-independent reaction Y(g)+2C(s)?YC2(g), second- and third-law methods yielded D00=1556 kcal mole?1 and D00=1565 kcal mole?1, respectively, for the Y&sngbnd;C2 bond energy. An estimated heat

G. de Maria; M. Guido; L. Malaspina; B. Pesce

1965-01-01

423

Intermediary carbon metabolism in Frankia  

Microsoft Academic Search

Frankia isolate NPI 0136010 was able to use only propionate and acetate as sole carbon sources and was unable to use hexoses, pentoses, disaccharides, and trisaccharides. Cell free extracts were surveyed for key enzymes of intermediary carbon metabolism. Enzymes of the Embden-Meyerhof-Parnas (EMP) pathway, the tricarboxylic acid (TCA) cycle and glyoxylate shunt were detected while enzymes of the pentose phosphate

M. D. Stowers; R. K. Kulkarni; D. B. Steele

1986-01-01

424

Carbon budgets in symbiotic associations  

SciTech Connect

Methods are described which permit the estimation of daily budgets for photosynthetically fixed carbon in any alga-invertebrate symbiosis. Included is a method for estimating total daily translocation which does not involve the use of C-14. A daily carbon budget for a shallow water symbiotic reef coral is presented.

Muscatine, L.; Falkowski, P.G.; Dubinsky, Z.

1983-01-01

425

Carbon Microtubes from Chicken Feathers  

Microsoft Academic Search

Chicken feathers, an agricultural waste problem, are a promising bio-based alternative to composite reinforcement. Approximately 5 billion pounds of chicken feathers are produced per year in the United States poultry industry alone. Containing 47.83% carbon, chicken feathers are hollow and strong in nature due to the 91% keratin content. Carbonized chicken feather (CCF) fibers are produced by heating to 220

Melissa M. Miller; Richard P. Wool

2007-01-01

426

Coral reefs and carbon dioxide  

SciTech Connect

This commentary argues the conclusion from a previous article, which investigates diurnal changes in carbon dioxide partial pressure and community metabolism on coral reefs, that coral `reefs might serve as a sink, not a source, for atmospheric carbon dioxide.` Commentaries from two groups are given along with the response by the original authors, Kayanne et al. 27 refs.

Buddemeier, R.W. [Kansas Geological Survey, Lawrence, KS (United States)

1996-03-01

427

Modern Carbon Composite Brake Materials  

Microsoft Academic Search

Carbon-carbon composites used in friction systems are becoming increasingly popular in aircrafts owing to their combination of low weight and high performance. Their current acceptance as brake materials is somewhat restrained due to two factors: cost and performance variations. Many manufacturers are taking steps toward improving their cost efficiency by utilizing lower cost precursor fibers and processing methodologies. At the

Christopher Byrne

2004-01-01

428

BIG SKY CARBON SEQUESTRATION PARTNERSHIP  

Microsoft Academic Search

The Big Sky Carbon Sequestration Partnership, led by Montana State University, is comprised of research institutions, public entities and private sectors organizations, and the Confederated Salish and Kootenai Tribes and the Nez Perce Tribe. Efforts under this Partnership fall into four areas: evaluation of sources and carbon sequestration sinks; development of GIS-based reporting framework; designing an integrated suite of monitoring,

Susan M. Capalbo

2004-01-01

429

Tungsten disulphide sheathed carbon nanotubes.  

PubMed

An insulated nanotube wire is formed by the binary phase of layered tungsten disulphide and carbon nanotubes (shown in the HRTEM image) generated by the sulphidization of tungsten oxide coated multiwalled carbon nanotubes at 900 C. Thermogravimetric analysis shows that the tungsten disulphide coat acts as an antioxidant. PMID:23686882

Whitby, R L; Hsu, W K; Boothroyd, C B; Fearon, P K; Kroto, H W; Walton, D R

2001-10-15

430

Sedimentary carbonates through Phanerozoic time  

Microsoft Academic Search

Plate tectonic processes play a critical role in the origin and distribution of sedimentary carbonates through Phanerozoic time. The Phanerozoic age distribution of sedimentary properties like calcite\\/ dolomite ratio, inferred oid and cement mineralogy, and survival rate of continental carbonates is cyclic. The cycles appear to be coupled to plate tectonic processes that give rise to global sea level change

Fred T. MacKenzie; John W. Morse

1992-01-01

431

Local structure of nanoporous carbons  

Microsoft Academic Search

The local atomic structure of nanoporous carbons produced by pyrolysis of poly(furfuryl alcohol) at various temperatures has been studied using neutron diffraction. Atomic pair distribution functions (PDFs) were obtained from the neutron data. Structure models have been fitted to the PDFs to understand the fine features of atomic ordering. It has been found that carbons produced at 800 and 1200

V. Petkov; R. G. Difrancesco; S. J. L. Billinge; M. Acharya; H. C. Foley

1999-01-01

432

Local structure of nanoporous carbons  

Microsoft Academic Search

The local atomic structure of nanoporous carbons produced by pyrolysis of poly(furfuryl alcohol) at various temperatures has been studied using neutron diffraction. Atomic pair distribution functions (PDFs) were obtained from the neutron data. Structure models have been fitted to the PDFs to understand the fine features of atomic ordering. It has been found that carbons produced at 800 and 1200C

V. Petkov; R. G. Difrancesco; S. J. L. Billinge; M. Acharya; H. C. Foley

1999-01-01

433

Polymer Nanocomposites Containing Carbon Nanotubes  

Microsoft Academic Search

We review the present state of polymer nanocomposites research in which the fillers are single- wall or multiwall carbon nanotubes. By way of background we provide a brief synopsis about carbon nanotube materials and their suspensions. We summarize and critique various nanotube\\/polymer composite fabrication methods including solution mixing, melt mixing, and in situ polymerization with a particular emphasis on evaluating

Mohammad Moniruzzaman; Karen I. Winey

2006-01-01

434

CARBON NANOTUBES AS MULTIPOLLUTANT SORBENTS  

EPA Science Inventory

Exploratory Research Program Project - Carbon nanotubes (CNTs) are formed from graphite (or graphene) sheets rolled into tubes, typically with diameters of 1 - 10 nm and lengths of 200 - 500 nm. Carbon nanotubes have unique electrical properties that have led to interest in thei...

435

Forest soils and carbon sequestration  

Microsoft Academic Search

Soils in equilibrium with a natural forest ecosystem have high carbon (C) density. The ratio of soil:vegetation C density increases with latitude. Land use change, particularly conversion to agricultural ecosystems, depletes the soil C stock. Thus, degraded agricultural soils have lower soil organic carbon (SOC) stock than their potential capacity. Consequently, afforestation of agricultural soils and management of forest plantations

R. Lal

2005-01-01

436

Carbon Sequestration Research and Development.  

National Technical Information Service (NTIS)

The goal of this report is to identify key areas for research and development (R&D) that could lead to an understanding of the potential for future use of carbon sequestration as a major tool for managing carbon emissions. Under the leadership of DOE, res...

A. Palmisano A. Wolsky B. Kane D. Reichle G. Hendrey G. Jacobs H. Herzog J. Clarke J. Ekmann J. Houghton J. Hunter-Cevera J. Ogden J. Stringer M. York N. Woodward R. Dahlman R. Judkins R. Socolow S. Benson T. Surles

1999-01-01

437

Carbon nanotubes in interconnect applications  

Microsoft Academic Search

Carbon nanotubes with their outstanding electrical and mechanical properties are suggested as an interconnect material of the future. In this paper we will introduce nanotubes, compare their electrical properties with equivalent metal wires made of gold and describe our progress in process integration. Multi-walled carbon nanotubes are grown on 6-inch wafers in a batch process. The resulting nanotubes are evaluated

Franz Kreupl; Andrew P. Graham; G. S Duesberg; W Steinhgl; M Liebau; Eugen Unger; W Hnlein

2002-01-01

438

Carbon partitioning to cellulose synthesis  

Microsoft Academic Search

This article discusses the importance and implications of regulating carbon partitioning to cellulose synthesis, the characteristics of cells that serve as major sinks for cellulose deposition, and enzymes that participate in the conversion of supplied carbon to cellulose. Cotton fibers, which deposit almost pure cellulose into their secondary cell walls, are referred to as a primary model system. For sucrose

Candace H. Haigler; Milka Ivanova-Datcheva; Patrick S. Hogan; Vadim V. Salnikov; Sangjoon Hwang; Kirt Martin; Deborah P. Delmer

2001-01-01

439

Carbon nanofibers for composite applications  

Microsoft Academic Search

Carbon nanofibers and nanotubes are promising to revolutionise several fields in material science and are suggested to open the way into nanotechnology. Further market development will depend on material availability at reasonable prices. We have achieved bulk production capacities of high purity carbon nanofibers (CNFs) at low cost by a catalytic chemical vapour deposition (CCVD) process. Reasonably low temperatures and

E. Hammel; X. Tang; M. Trampert; T. Schmitt; K. Mauthner; A. Eder; P. Ptschke

2004-01-01

440

Advancing Climate and Carbon Simulation.  

National Technical Information Service (NTIS)

We use a recently developed integrated climate/carbon model to perform breakthrough studies of the climate. Two major studies are carried out--namely the effects of CO(sub 2)-fertilized vegetation on global climate and carbon dynamics, and the effect of c...

S. Thompson

2004-01-01

441

Adatoms and nanoengineering of carbon  

Microsoft Academic Search

We present a new and general mechanism for inter-conversion of carbon structures via a catalytic exchange process, which operates under conditions of Frenkel pair generation. The mechanism typically lowers reaction barriers by a factor of four compared to equivalent uncatalysed reactions. We examine the relevance of this mechanism for fullerene growth, carbon onions and nanotubes, and dislocations in irradiated graphite.

C. P. Ewels; M. I. Heggie; P. R. Briddon

2002-01-01

442

Catalytic activation of carbon monoxide  

Microsoft Academic Search

Research into the catalytic activation of carbon monoxide has direct applications to the industrial use of synthesis gas as a feedstock for manufacturing synfuels and other organic chemicals. Synthesis gas is comprised of hydrogen\\/carbon monoxide mixtures produced from coal and other carbonaceous materials. Its potential uses include production of oxygenated organic material such as methanol and ethylene glycol, conversion to

Ford

1981-01-01

443

Investigations of carbon implanted silicon  

Microsoft Academic Search

Buried layers have been produced by implanting carbon with an energy of 100 keV in silicon wafers and subsequent annealing. These layers were used as an etch stop in KOH. The samples were analyzed with RBS, channeling and PIXE with regard to the depth distribution of carbon, the annealing of the silicon layer at the surface and the effect of

D. Frse; D. Kollewe; W. von Mnch

1993-01-01

444

Investigations of carbon implanted silicon  

Microsoft Academic Search

Buried layers have been produced by implanting carbon with an energy of 100 keV in silicon wafers and subsequent annealing. These layers were used as etch stop in KOH. The samples were analyzed with RBS, channeling and FIXE with regard to the depth distribution of carbon, the annealing of the silicon layer at the surface and the effect of segregation.

D. Frse; D. Kollewe; W. von Mnch

1992-01-01

445

Diamond-like amorphous carbon  

Microsoft Academic Search

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with significant sp3 bonding. DLC is a semiconductor with a high mechanical hardness, chemical inertness, and optical transparency. This review will describe the deposition methods, deposition mechanisms, characterisation methods, electronic structure, gap states, defects, doping, luminescence, field emission, mechanical properties and some applications of DLCs. The films have widespread applications

J. Robertson

2002-01-01

446

Carbon Footprinting: A classroom exercise  

Microsoft Academic Search

This document outlines a carbon footprinting methodology that can be conducted by graduate or undergraduate students as a classroom exercise. A class of graduate students at Arizona State University in the College of Design and School of Sustainability used a methodology to determine the carbon footprint of three campus buildings. This methodology included an energy consumption analysis of the existing

HARVEY BRYAN; MARIA GRIMM

447

Carbon nanotubes for power applications  

Microsoft Academic Search

Carbon nanotubes have been found to possess a wide variety of extremely remarkable properties, most notably high electrical and thermal conductivity, mechanical strength, and catalytic surface area. These properties imbue carbon nanotubes with tremendous potential for a variety of power generation and storage devices including: lithium-ion (Li+) batteries, polymeric solar cells, proton exchange membrane (PEM) fuel cells, and thermionic power

R. P. Raffaelle; B. J. Landi; J. D. Harris; S. G. Bailey; A. F. Hepp

2005-01-01

448

Acoustoelectric Effects in Carbon Nanotubes  

Microsoft Academic Search

We report observations of acoustoelectric effects in carbon nanotubes. We excite sound in mum long ropes of single walled carbon nanotubes suspended between two metallic contacts by applying radio-frequency electric field. The sound is detected by measuring either the dc resistance of the tubes in a region of strong temperature dependence (in the vicinity of superconducting or metal-insulator transition), or

B. Reulet; A. Yu. Kasumov; M. Kociak; R. Deblock; I. I. Khodos; Yu. B. Gorbatov; V. T. Volkov; C. Journet; H. Bouchiat

2000-01-01

449

Carbon Footprint Exercise  

NSDL National Science Digital Library

Step 1. Students are asked to keep track of their energy use from a variety of sources (heating/cooling, electricity, transportation, secondary emissions, etc) during the 9 days of Thanksgiving break, when many of them are likely to travel. They use the total for the 9 days that they calculated using an online calculator to estimate their yearly footprint and compare it to US and world averages. For most of them, the amount of carbon emitted during those 9 days is quite large because of airplane travel or long-distance driving. However, using a week of break when many students will travel allows them to become aware of the significance of transportation in carbon emissions. We provided a table with electricity and heating/cooling bills for various residence halls for students who stay on campus during the break. Step 2. Students complete an online survey where they are asked to enter the values that they have obtained for the various components of the calculator, perform some simple calculations and compare their annual footprint to the U.S. average. We used SurveyGizmo for the survey because it allows to download the data in a spreadsheet format and has some limited plotting features. The free version allows a maximum of 250 submissions, the Basic version ($19 per month, can be canceled at any time) has unlimited submissions. Step 3. Students write an essay through BlackBoard/WebCT (Assignment). A few guiding questions are provided for this essay where students reflect on the results of their impact on the global carbon budget, what they found surprising, and if they plan to make any changes to their lifestyle to limit their impact. No length limit is set for the essay. The guidelines and components of this assignment are available on a wiki page. The three steps can be implemented in BlackBoard/WebCT as a Lesson Plan with links to the online calculator (step 1), to the survey (step 2), and to the Assignment/essay (step 3).

Cervato, Cinzia

450

21 CFR 582.1619 - Potassium carbonate.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Potassium carbonate. 582.1619 Section 582.1619...General Purpose Food Additives § 582.1619 Potassium carbonate. (a) Product. Potassium carbonate. (b) Conditions of use....

2013-04-01

451

Assessment of Household Carbon Footprint Reduction Potentials.  

National Technical Information Service (NTIS)

The term 'household carbon footprint' refers to the total annual carbon emissions associated with household consumption of energy, goods, and services. In this project, Lawrence Berkeley National Laboratory developed a carbon footprint modeling framework ...

E. Masanet E. Worrell G. Homan K. J. Kramer R. Brown

2009-01-01

452

21 CFR 73.1070 - Calcium carbonate.  

Code of Federal Regulations, 2013 CFR

...Specifications. Calcium carbonate shall meet the specifications for precipitated calcium carbonate in the United States Pharmacopeia XX (1980). (c) Uses and restrictions. Calcium carbonate may be safely used in amounts...

2013-04-01

453

21 CFR 184.1191 - Calcium carbonate.  

Code of Federal Regulations, 2013 CFR

...As a byproduct in the Lime soda process; (2) By precipitation of calcium carbonate from calcium hydroxide in the Carbonation process; or (3) By precipitation of calcium carbonate from calcium chloride in the Calcium...

2013-04-01

454

The Carbon Crisis in 90 Seconds  

NSDL National Science Digital Library

This video features a short animated sequence that illustrates the difference between young and old carbon released into the atmosphere from the consumption of food (young carbon) and the burning of fossil fuels (old carbon).

Nasa

455

Lifetime of Excess Atmospheric Carbon Dioxide.  

National Technical Information Service (NTIS)

The authors explore the effects of a changing terrestrial biosphere on the atmospheric residence time of carbon dioxide using three simple ocean carbon cycling models and a model of global terrestrial carbon cycling. We find differences in model behavior ...

B. Moore B. H. Braswell

1994-01-01

456

40 CFR Table - Carbon Monoxide Emission Limits  

Code of Federal Regulations, 2010 CFR

...to Subpart Aaaa of Part 60 - Carbon Monoxide Emission Limits] 40 PROTECTION...Subpart AAAA of Part 60--Carbon Monoxide Emission Limits for New Small Municipal...averaging times combustion units carbon monoxide limits...

2009-07-01

457

16 CFR 260.5 - Carbon offsets.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Carbon offsets. 260.5 Section 260.5 Commercial...ENVIRONMENTAL MARKETING CLAIMS § 260.5 Carbon offsets. (a) Given the complexities of carbon offsets, sellers should employ...

2013-01-01

458

In situ optical emission study on the role of C2 in the synthesis of single-walled carbon nanotubes  

Microsoft Academic Search

In situ optical emission spectroscopy was used to study the temporal and spatial behavior of laser induced plasmas in the laser-furnace synthesis of single-walled carbon nanotubes (SWCNTs). A graphite composite target located within a sealed quartz tube with a chemical stoichiometric composition of 95:4:1 at. wt % of carbon, yttrium, and nickel, respectively, was ablated by a Q-switched Nd:YAG laser

David Edmond Motaung; Mathew Kisten Moodley; E. Manikandan; Neil J. Coville

2010-01-01

459

Carbon nanotubes: engineering biomedical applications.  

PubMed

Carbon nanotubes (CNTs) are cylinder-shaped allotropic forms of carbon, most widely produced under chemical vapor deposition. They possess astounding chemical, electronic, mechanical, and optical properties. Being among the most promising materials in nanotechnology, they are also likely to revolutionize medicine. Among other biomedical applications, after proper functionalization carbon nanotubes can be transformed into sophisticated biosensing and biocompatible drug-delivery systems, for specific targeting and elimination of tumor cells. This chapter provides an introduction to the chemical and electronic structure and properties of single-walled carbon nanotubes, followed by a description of the main synthesis and post-synthesis methods. These sections allow the reader to become familiar with the specific characteristics of these materials and the manner in which these properties may be dependent on the specific synthesis and post-synthesis processes. The chapter ends with a review of the current biomedical applications of carbon nanotubes, highlighting successes and challenges. PMID:22093220

Gomez-Gualdrn, Diego A; Burgos, Juan C; Yu, Jiamei; Balbuena, Perla B

2011-01-01

460

Ex situ aqueous mineral carbonation  

SciTech Connect

The U.S. Department of Energy's National Energy Technology Laboratory (NETL) located in Albany, OR (formerly the Albany Research Center) has studied ex situ mineral carbonation as a potential option for carbon dioxide sequestration. Studies focused on the reaction of Ca-, Fe-, and Mg-silicate minerals with gaseous CO{sub 2} to form geologically stable, naturally occurring solid carbonate minerals. The research included resource evaluation, kinetic studies, process development, and economic evaluation. An initial cost estimate of about $69/ton of CO{sub 2} sequestered was improved with process improvements to about 54/ton. The scale of ex situ mineral carbonation operations, requiring about 55,000 tons of mineral to carbonate, the daily CO{sub 2} emissions from a 1-GW, coal-fired power plant, may make such operations impractical. 23 refs., 4 figs., 5 tabs.

Stephen J. Gerdemann; William K. O'Connor; David C. Dahlin; Larry R. Penner; Hank Rush [National Energy Technology Laboratory, Albany, OR (United States)

2007-04-01

461

Ex Situ Aqueous Mineral Carbonation  

SciTech Connect

The U.S. Department of Energy's National Energy Technology Laboratory (NETL) located in Albany, OR (formerly the Albany Research Center) has studied ex situ mineral carbonation as a potential option for carbon dioxide sequestration. Studies focused on the reaction of Ca-, Fe-, and Mg-silicate minerals with gaseous CO2 to form geologically stable, naturally occurring solid carbonate minerals. The research included resource evaluation, kinetic studies, process development, and economic evaluation. An initial cost estimate of ~$69/ton of CO2 sequestered was improved with process improvements to ~$54/ton. The scale of ex situ mineral carbonation operations, requiring ~55 000 tons of mineral to carbonate, the daily CO2 emissions from a 1-GW, coal-fired power plant, may make such operations impractical.

Gerdemann, S.J.; O'Connor, W.K.; Dahlin, D.C.; Penner, L.R.; Rush, G.E.

2007-04-01

462

Natural materials for carbon capture.  

SciTech Connect

Naturally occurring clay minerals provide a distinctive material for carbon capture and carbon dioxide sequestration. Swelling clay minerals, such as the smectite variety, possess an aluminosilicate structure that is controlled by low-charge layers that readily expand to accommodate water molecules and, potentially, carbon dioxide. Recent experimental studies have demonstrated the efficacy of intercalating carbon dioxide in the interlayer of layered clays but little is known about the molecular mechanisms of the process and the extent of carbon capture as a function of clay charge and structure. A series of molecular dynamics simulations and vibrational analyses have been completed to assess the molecular interactions associated with incorporation of CO2 in the interlayer of montmorillonite clay and to help validate the models with experimental observation.

Myshakin, Evgeniy M. (National Energy Technology Laboratory, Pittsburgh, PA); Romanov, Vyacheslav N. (National Energy Technology Laboratory, Pittsburgh, PA); Cygan, Randall Timothy

2010-11-01

463

Graphitic carbon nanostructures from cellulose  

NASA Astrophysics Data System (ADS)

Graphitic carbon nanostructures have been synthesized from cellulose via a simple methodology that essentially consists of the steps: (i) hydrothermal treatment of cellulose at 250 C and (ii) impregnation of the carbonaceous product with a nickel salt followed by thermal treatment at 900 C. The formation of graphitic carbon nanostructures seems to occur by a dissolution-precipitation mechanism in which amorphous carbon is dissolved in the catalyst nanoparticles and then precipitated as graphitic carbon around the catalyst particles. The subsequent removal of the nickel nanoparticles and amorphous carbon by oxidative treatment leads to graphitic nanostructures with a coil morphology. This material exhibits a high degree of crystallinity and large and accessible surface area.

Sevilla, M.; Fuertes, A. B.

2010-04-01

464

Carbon dioxide: atmospheric overload  

SciTech Connect

The level of carbon dioxide in the atmosphere is increasing and may double within the next century. The result of this phenomenon, climatic alterations, will adversely affect crop production, water supplies, and global temperatures. Sources of CO2 include the combustion of fossil fuels, photosynthesis, and the decay of organic matter in soils. The most serious effect of possible climatic changes could occur along the boundaries of arid and semiarid regions. Shifts is precipitation patterns could accelerate the processes of desertification. An increase of 5..cap alpha..C in the average temperature of the top 1000 m of ocean water would raise sea level by 2 m. CO2 releases to the atmosphere can be reduced by controlling emissions from fossil fuel-fired facilities and by careful harvesting of forest regions. (3 photos, 5 references)

Not Available

1980-04-01

465

Toxicity of carbon nanotubes.  

PubMed

Carbon nanotubes (CNTs) find their extensive application as a promising material in medicine due to unique characteristics. However, such materials have been accompanied with potentially hazardous effects on human health. The toxicity of CNTs may vary depending on their structural characteristics, surface properties and chemical composition. To gain insight into the toxicity of CNTs in vivo and in vitro, we summarize contributing factors for the toxic effects of CNTs in this review. In addition, we elaborate on the toxic effects and mechanisms in target sites at systemic, organic, cellular, and biomacromolecule levels. Various issues are reported to be effected when exposed to CNTs including (1) blood circulation, (2) lymph circulation, (3) lung, (4) heart, (5) kidney, (6) spleen, (7) bone marrow, and (8) blood brain barrier. Though there have been published reports on the toxic effects of CNTs to date, more studies will still be needed to gain full understanding of their potential toxicity and underlying mechanisms. PMID:24016107

Wang, Jing; Xu, Yuanzhi; Yang, Zhi; Huang, Renhuan; Chen, Jing; Wang, Raorao; Lin, Yunfeng

2013-08-01

466

Carbon nanotube intramolecular devices  

NASA Astrophysics Data System (ADS)

By introducing a pentagon and a heptagon into the hexagonal carbon lattice, two nanotube segments with different atomic and electronic structures can be seamlessly fused together to create junctions within a single nanotube molecule. These junctions could form building blocks for nanotube-based molecular electronics. We have performed electrical measurements of nanotubes with such intramolecular junctions. We find that a metal-semiconductor junction behaves as a rectifying diode with nonlinear and strongly asymmetric current-voltage characteristics. In the case of a metal-metal junction, the conductance appears to be strongly suppressed and it displays a power-law dependence on temperature and voltage, consistent with tunneling between the ends of two Luttinger liquids. We will also discuss intramolecular devices created by mechanical deformation. [1] Z. Yao, H. Postma, L. Balents and C. Dekker, Nature 402, 273 (1999).

Yao, Zhen; Postma, Henk; Dekker, Cees

2000-03-01

467

Carbon Nanotube based Nanotechnolgy  

NASA Astrophysics Data System (ADS)

Carbon nanotube(CNT) was discovered in the early 1990s and is an off-spring of C60(the fullerene or buckyball). CNT, depending on chirality and diameter, can be metallic or semiconductor and thus allows formation of metal-semiconductor and semiconductor-semiconductor junctions. CNT exhibits extraordinary electrical and mechanical properties and offers remarkable potential for revolutionary applications in electronics devices, computing and data storage technology, sensors, composites, storage of hydrogen or lithium for battery development, nanoelectromechanical systems(NEMS), and as tip in scanning probe microscopy(SPM) for imaging and nanolithography. Thus the CNT synthesis, characterization and applications touch upon all disciplines of science and engineering. A common growth method now is based on CVD though surface catalysis is key to synthesis, in contrast to many CVD applications common in microelectronics. A plasma based variation is gaining some attention. This talk will provide an overview of CNT properties, growth methods, applications, and research challenges and opportunities ahead.

Meyyappan, M.

2000-10-01

468

Carbon emissions control strategies  

SciTech Connect

This study was undertaken to address a fundamental issue: the cost of slowing climate change. Experts in eight nations were asked to evaluate, using the best economic models available, the prospects for reducing fossil fuel-based carbon emissions in their respective nations. The nations selected as case studies include: the Soviet Union, Poland, the United States, Japan, Hungary, France, the United Kingdom, and Canada. As important contributors to the greenhouse effect, these industrialized nations must find ways to substantially reduce their emissions. This is especially critical given that developing nations' emissions are expected to rise in the coming decades in the search for economic development. Ten papers have been processed separately for inclusion in the appropriate data bases.

Chandler, W.U. (ed.)

1990-01-01

469

Diamond, Carbide and Carbonate Planets  

NASA Astrophysics Data System (ADS)

More than five hundred planets have been discovered outside of our solar system to date, yet very little is known of their internal compositions and subsequent mineralogy. The principal factors in determining planetary mineralogy are nebula composition, pressure, temperature and oxygen fugacity. While work has been done on determining the stable minerals with respect to pressure and temperature in these planets, very little has been done in determining the oxygen fugacity and the resulting geology. Planetary formation models propose a new kind of planet: carbon super-Earths. The planets have very high C/Fe ratios and are unlike any in our solar system. The interplay between carbon, oxygen and iron in these planets provide an end-member test of the effects of oxygen fugacity on carbon mineralogy as well as the potential for carbon entering Earth's core as iron-carbide. We combine experimental diamond anvil cell x-ray diffraction and Raman spectroscopy with thermochemical modeling to determine the oxidation state and relative oxidation potential of the siderite-diamond-wstite (SDW) buffer relative to the iron-wstite (IW) buffer over a range of pressures spanning those of Earth's lower mantle to that of a carbon super-Earth. We find that over all pressures along a mantle adiabat, the SDW buffer is above the IW buffer, suggesting that both the Earth and carbon super-Earth mantles contain reduced species of carbon. Experiments to 65 GPa and 2400 K on siderite, iron, and wstite mixtures show reduction of carbon to diamond via x-ray diffraction, Raman spectroscopy, and STEM-EDX. The reduced carbon present in these planets will therefore be present as iron carbide with excess diamond. In a carbon super-Earth, differentiation processes will sequester iron carbide into a core, leaving a significant inventory of diamond in the mantle. We present mass-radius relationships for such planets and implications for the dynamical evolution of diamond-rich mantles.

Unterborn, C. T.; Panero, W. R.; Kabbes, J. E.

2011-12-01

470

Carbon Nanotube Production in CO Laser Pumped Carbon Monoxide Plasmas  

NASA Astrophysics Data System (ADS)

A novel method for the synthesis of carbon nanotubes will be presented. Carbon monoxide in a CO-Ar gas mixture is optically pumped using a continuous wave CO laser. The CO molecules absorb the laser radiation on the lowest 10 vibrational transitions and transfer energy to high vibrational states by vibration-vibration energy exchange collisions. This leads to a highly nonequilibrium energy distribution in the CO which provides enough energy for the CO disproportionation reaction to occur: CO + CO arrow C + CO_2. This experimental technique consequently produces the free carbon necessary for the growth of carbon nanotubes and other carbon clusters while maintaining near room temperature in the plasma. Our technique can produce substantial quantities of nanotubes at low pressure (50 Torr) due to the efficient carbon production and is scalable to higher pressures and therefore, to larger production quantities. We will present the effect of metal catalysts on production rates and nanotube quality for our experimental technique as well as effects of plasma temperature and gas pressures. Single- and multi-walled carbon nanotubes have been observed in the deposited material with concentrations of better than 50 %. The plasma conditions are monitored using emission spectroscopy.

Ploenjes, Elke; Palm, Peter; Subramaniam, Vish; Adamovich, Igor; Rich, William; Viswanathan, Babu; Fraser, Hamish

2000-10-01

471

Organic carbon in soil and the global carbon cycle  

SciTech Connect

Soil organic matter is, simultaneously, the most inert carbon cycle component of terrestrial ecosystems, and the most dynamic component of terrestrail geologic systems placing it in a pivotal position in the biogeochemistry of carbon. The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C{center dot}yr{sup {minus}1} is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. However, the input rates and decomposition rates for different terrestrial ecosystems vary over several orders of magnitude resulting in widely different amounts and turnover rates of soil organic matter. The amounts of carbon stored in soils and the rates of exchange of soil carbon with the atmosphere depend on many factors related to the chemistry, biology, and physics of soil and soil organic matter. This report discusses work on organic carbon in soil and aspects of the carbon cycle.

Post, W.M. III.

1991-01-01

472

Reduction of carbon dioxide on modified glassy carbon electrodes  

SciTech Connect

Carbon dioxide in the atmosphere gives an important contribution to environmental pollution due to the progressive increase of its production everywhere from many sources. It is believed now that the capacity of the biosphere, due to absorption and transformation of CO{sub 2}, has been considerably exceeded and many attempts to overcome this problem by different ways, have been successful. Electrochemical reduction seems to be an appropriate route for carbon dioxide consumption and its transformation to useful compounds. Electrochemical reduction of carbon dioxide on glassy carbon (GC) was studied by applying different potential regimes and monitoring the effect of the electrode surface conditioning, as well as the nature of supporting electrolyte, upon the nature of the reaction. In the case of constant potential electrolyses, a rapid decay of the cathodic current was observed, while application of a suitable pulse program to the working electrode, in addition to the ultrasonic cleaning of the surface, allowed completion of the reaction without premature current downfall. Modification of the electrode surface, by applying potential pulses, caused a decrease of the reduction potential of CO{sub 2} on glassy carbon. High yields in carbon monoxide and methanol were obtained in these media, with the highest value obtained for methanol in sodium chloride and carbon monoxide in ammonium oxalate.

Hernandez, R.M.; Marquez, J.; Marquez, O.P.; Choy, M.; Ovalles, C.; Garcia, J.J.; Scharifker, B.

1999-11-01

473

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon  

SciTech Connect

Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300 deg. C for an hour in each step. The catalytic growth of nanocarbon in C{sub 2}H{sub 4}/H{sub 2} was carried out at temperature of 550 deg. C for 2 hrs with different rotating angle in the fluidization system. SEM and N{sub 2} isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

Abdullah, N.; Muhammad, I. S.; Hamid, S. B. Abd. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Rinaldi, A. [NANOCEN, Block A, Level 3, Institute of Postgraduate Studies, University of Malaya, 50603 Kuala Lumpur (Malaysia); Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany); Su, D. S.; Schlogl, R. [Inorganic Chemistry Department, Fritz-Haber Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin (Germany)

2009-06-01

474

Growth of carbon nanostructures on carbonized electrospun nanofibers with palladium nanoparticles  

NASA Astrophysics Data System (ADS)

This paper studies the mechanism of the formation of carbon nanostructures on carbon nanofibers with Pd nanoparticles by using different carbon sources. The carbon nanofibers with Pd nanoparticles were produced by carbonizing electrospun polyacrylonitrile (PAN) nanofibers including Pd(Ac)2. Such PAN-based carbon nanofibers were then used as substrates to grow hierarchical carbon nanostructures. Toluene, pyridine and chlorobenzine were employed as carbon sources for the carbon nanostructures. With the Pd nanoparticles embedded in the carbonized PAN nanofibers acting as catalysts, molecules of toluene, pyridine or chlorobenzine were decomposed into carbon species which were dissolved into the Pd nanoparticles and consequently grew into straight carbon nanotubes, Y-shaped carbon nanotubes or carbon nano-ribbons on the carbon nanofiber substrates. X-ray diffraction analysis and transmission electron microscopy (TEM) were utilized to capture the mechanism of formation of Pd nanoparticles, regular carbon nanotubes, Y-shaped carbon nanotubes and carbon nano-ribbons. It was observed that the Y-shaped carbon nanotubes and carbon nano-ribbons were formed on carbonized PAN nanofibers containing Pd-nanoparticle catalyst, and the carbon sources played a crucial role in the formation of different hierarchical carbon nanostructures.

Lai, Chuilin; Guo, Qiaohui; Wu, Xiang-Fa; Reneker, Darrell H.; Hou, Haoqing

2008-05-01

475

Growth of carbon nanostructures on carbonized electrospun nanofibers with palladium nanoparticles.  

PubMed

This paper studies the mechanism of the formation of carbon nanostructures on carbon nanofibers with Pd nanoparticles by using different carbon sources. The carbon nanofibers with Pd nanoparticles were produced by carbonizing electrospun polyacrylonitrile (PAN) nanofibers including Pd(Ac)(2). Such PAN-based carbon nanofibers were then used as substrates to grow hierarchical carbon nanostructures. Toluene, pyridine and chlorobenzine were employed as carbon sources for the carbon nanostructures. With the Pd nanoparticles embedded in the carbonized PAN nanofibers acting as catalysts, molecules of toluene, pyridine or chlorobenzine were decomposed into carbon species which were dissolved into the Pd nanoparticles and consequently grew into straight carbon nanotubes, Y-shaped carbon nanotubes or carbon nano-ribbons on the carbon nanofiber substrates. X-ray diffraction analysis and transmission electron microscopy (TEM) were utilized to capture the mechanism of formation of Pd nanoparticles, regular carbon nanotubes, Y-shaped carbon nanotubes and carbon nano-ribbons. It was observed that the Y-shaped carbon nanotubes and carbon nano-ribbons were formed on carbonized PAN nanofibers containing Pd-nanoparticle catalyst, and the carbon sources played a crucial role in the formation of different hierarchical carbon nanostructures. PMID:21825712

Lai, Chuilin; Guo, Qiaohui; Wu, Xiang-Fa; Reneker, Darrell H; Hou, Haoqing

2008-04-07

476

Carbon scaffolding: building acetylenic all-carbon and carbon-rich compounds  

Microsoft Academic Search

The preparation of acetylenic molecular and polymeric carbon allotropes and carbon-rich nanometre-sized structures opens new avenues of fundamental and technological research at the interface between chemistry and materials science. Unusual structures, high stability and useful electrical and nonlinear optical properties are some of the desirable characteristics of these materials.

Franois Diederich

1994-01-01

477

Net carbon flux from agriculture: Carbon emissions, carbon sequestration, crop yield, and land-use change  

Microsoft Academic Search

There is a potential to sequester carbon in soil by changing agricultural management practices. These changes in agricultural management can also result in changes in fossil-fuel use, agricultural inputs, and the carbon emissions associated with fossil fuels and other inputs. Management practices that alter crop yields and land productivity can affect the amount of land used for crop production with

Tristram O. West; Gregg Marland

2003-01-01

478

A 400 million year carbon isotope record of pedogenic carbonate: Implications for paleoatmospheric carbon dioxide  

Microsoft Academic Search

A 400 record of atmospheric carbon dioxide levels has been estimated by applying a CO paleobarometer to a database of 758 analyses of paleosol (fossil soil) carbonates. This database is a compilation of new data and previously published values from the literature. Many new analyses of Mesozoic paleosols are reported, an era poorly represented in the literature. Results indicate that

D. D. Ekart; T. E. Cerling; I. P. Montanez; N. J. Tabor

1999-01-01

479

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

PubMed

Hierarchical carbon nanostructures based on ultra-long carbon nanofibers (CNF) decorated with carbon nanotubes (CNT) have been prepared using plasma processes. The nickel/carbon composite nanofibers, used as a support for the growth of CNT, were deposited on nanopatterned silicon substrate by a hybrid plasma process, combining magnetron sputtering and plasma-enhanced chemical vapor deposition (PECVD). Transmission electron microscopy revealed the presence of spherical nanoparticles randomly dispersed within the carbon nanofibers. The nickel nanoparticles have been used as a catalyst to initiate the growth of CNT by PECVD at 600C. After the growth of CNT onto the ultra-long CNF, SEM imaging revealed the formation of hierarchical carbon nanostructures which consist of CNF sheathed with CNTs. Furthermore, we demonstrate that reducing the growth temperature of CNT to less than 500C leads to the formation of carbon nanowalls on the CNF instead of CNT. This simple fabrication method allows an easy preparation of hierarchical carbon nanostructures over a large surface area, as well as a simple manipulation of such material in order to integrate it into nanodevices. PMID:21971265

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

2011-10-28

480

Carbon isotopic exchange between dissolved inorganic and organic carbon  

NASA Astrophysics Data System (ADS)

The pools of inorganic and organic carbon are often considered to be separate and distinct. Isotopic exchange between the inorganic and organic carbon pools in natural waters is rarely considered plausible at low temperatures owing to kinetic barriers to exchange. In certain circumstances, however carboxyl carbon of dissolved organic matter (DOM) may be subject to exchange with the dissolved inorganic carbon (DIC) pool. We report results from an isotopic labeling experiment that resulted in rapid methanogen-catalyzed isotopic exchange between DIC and the carboxyl carbon of acetate. This exchange rapidly mixes the isotopic composition of the DIC pool into the dissolved organic carbon (DOC) acetate pool. This exchange is likely associated with the reversible nature of the carbon monoxide dehydrogenase enzyme. In nature, many decarboxylase enzymes are also reversible and some can be shown to facilitate similar exchange reactions. Those decarboxylase enzymes that are important in lignin decomposition and other organic carbon (OC) transformations may help to mask the isotopic composition of the precursor DOC with as much as 15% contribution from DIC. Though this dilution is unlikely to matter in soils where DOC and DIC are similar in composition, this exchange may be extremely important in systems where the stable or radioisotope composition of DOC and DIC differ significantly. As an example of the importance of this effect, we demonstrate that the stable and radiocarbon isotopic composition of fluvial DOC could be altered by mixing with marine DIC to produce a DOC composition similar to those observed in the deep marine DOC pool. We hypothesize that this exchange resolves the conundrum of apparently old (>5 kyr) marine-derived DOC. If most of the carboxyl carbon of pre-aged, terrestrial-derived DOC (15% of total carbon) is subject to exchange with marine DIC, the resulting carbon isotopic composition of deep DOC will be similar to that observed in deep marine studies. DOC observed in the deep ocean might therefore have a terrestrial DOC carbon skeleton with a carboxyl-rich component that is marine in origin.

Thomas, B.; Freeman, K. H.; House, C. H.; Arthur, M. A.

2009-12-01

481

Electron field emission of carbon nanotubes on carbon felt  

Microsoft Academic Search

Carbon nanotubes (CNTs) synthesized directly onto carbon felt have been\\u000a investigated as electron field emission electrodes. This CNT\\/felt\\u000a composite was prepared using the decomposition of methanol on metal\\u000a catalyst supported on carbon felt. High-resolution transmission electron\\u000a microscopy and scanning electron microscopy were used to characterize\\u000a the microstructure of the films. Electron field emission was observed at\\u000a macroscopic field as low

J. Mauricio Rosolen; C. H. Patrick Poa; Simone Tronto; Marcel S. Marchesin; S. Ravi P. Silva

2006-01-01

482

Carbon Nanotube Templated Microfabrication of Porous Silicon-Carbon Materials  

NASA Astrophysics Data System (ADS)

Carbon nanotube templated microfabrication (CNT-M) of porous materials is demonstrated. Partial chemical infiltration of three dimensional carbon nanotube structures with silicon resulted in a mechanically robust material, precisely structured from the 10 nm scale to the 100 micron scale. Nanoscale dimensions are determined by the diameter and spacing of the resulting silicon/carbon nanotubes while the microscale dimensions are controlled by lithographic patterning of the CNT growth catalyst. We demonstrate the utility of this hierarchical structuring approach by using CNT-M to fabricate thin layer chromatography (TLC) separations media with precise microscale channels for fluid flow control and nanoscale porosity for high analyte capacity.

Song, Jun; Jensen, David; Dadson, Andrew; Vail, Michael; Linford, Matthew; Vanfleet, Richard; Davis, Robert

2010-10-01

483

Onion-like carbon and carbon nanotube film antennas  

NASA Astrophysics Data System (ADS)

In this paper, radiating dipole antennas have been fabricated from rolled carbon films, which are typically used for supercapacitor electrodes. Return loss and radiation pattern measurements for onion-like carbon (OLC) and multi-walled carbon nanotubes (MWCNTs) antenna samples are presented and compared to a copper standard. The OLC antenna's radiation pattern measurements show a peak gain of -1.48 dBi, just less than 3 dB of a copper dipole antenna. Compared to antennas made from MWCNT films, the OLC samples show better radiation performance despite a lower measured conductivity.

Vacirca, Nicholas A.; McDonough, John K.; Jost, Kristy; Gogotsi, Yury; Kurzweg, Timothy P.

2013-08-01

484

Fuel oxygenates: Organic carbonate synthesis  

SciTech Connect

Owing to the 1990 amendments to the Clean Air Act, two major programs, namely the oxygenated fuels program and the reformulated gasoline program have been mandated. Currently, ethers (MTBE, ETBE, and TAME) and alcohols (mainly ethanol) are employed as fuel oxygenates. However, several dialkyl carbonates exhibit attractive fuel properties and might emerge as future fuel oxygenates. This paper consists of an overview of related literature and highlight of some of our work on the synthesis of organic carbonates from C, feedstocks. Dialkyl carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) exhibit excellent gasoline blending properties such as high blending octane numbers and low blending Reid vapor pressures (RVP). Owing to their significantly higher oxygen content compared with alcohol (e.g., ethanol) and ether (e.g., MTBE, ETBE, and TAME) oxygenates, lower volume percent of the carbonate blending components will be needed to satisfy the 2.7 and 2.0 wt% oxygen requirements of the oxygenated and reformulated gasoline programs, respectively.

Bhattacharya, A.K. [Texaco Inc., Beacon, NY (United States)

1995-12-31

485

Hydrogen Adsorption in Carbon nanoparticles  

NASA Astrophysics Data System (ADS)

We have studied hydrogen adsorption in carbon nanoparticles using a quartz crystal microbalance. The carbon nanoparticles were synthesized from a thermal plasma jet at different pressure (15 -- 263 torr) of the reactants and different current (50 -- 250 A) to generate the plasma. The as-prepared carbon nanoparticles were directly deposited on top of the gold electrode of a quartz crystal and we monitored in-situ the changes in resonance frequency while the chamber was pressurized at different hydrogen pressures. These changes enabled determination of absorbed hydrogen mass in order to get H/C mass ratio curves as a function of H2 pressure. Adsorption curves obtained in some carbon nanoparticles indicated the formation of hydrogen monolayer inside the pores of the carbon nanoparticles. Using the value of the jump due to the formation of a H2monolayer, a surface area was estimated between 40-60 m^2/g for hydrogen adsorption. In other carbon samples, hydrogen uptake curves indicated that H2 was filling the sample's pores when pore volume was large. These observations will be discussed in detail for several carbon nanoparticles samples.

Cabrera, A. L.; Rojas, S.; Dias-Droguett, D. E.; Bhuyan, H.; Aomoa, N.; Kakati, M.

2013-03-01

486

TYPE Ia SUPERNOVA CARBON FOOTPRINTS  

SciTech Connect

We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II {lambda}6580 absorption 'notches' in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s{sup -1}) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22{sup +10}{sub -6%} of SNe Ia exhibit spectroscopic C II signatures as late as -5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II {lambda}6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a 'carbon blobs' hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

Thomas, R. C.; Nugent, P. [Computational Cosmology Center, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road MS 50B-4206, Berkeley, CA 94611 (United States); Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Hsiao, E. Y.; Loken, S. [Physics Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Antilogus, P.; Bongard, S.; Canto, A. [Laboratoire de Physique Nucleaire et des Hautes Energies, Universite Pierre et Marie Curie Paris 6, Universite Paris Diderot Paris 7, CNRS-IN2P3, 4 place Jussieu, 75252 Paris Cedex 05 (France); Baltay, C. [Department of Physics, Yale University, New Haven, CT 06250-8121 (United States); Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K. [Physikalisches Institut, Universitaet Bonn, Nussallee 12, 53115 Bonn (Germany); Chotard, N.; Copin, Y.; Gangler, E. [Universite de Lyon, F-69622 Lyon (France); and others

2011-12-10

487

Type Ia Supernova Carbon Footprints  

NASA Astrophysics Data System (ADS)

We present convincing evidence of unburned carbon at photospheric velocities in new observations of five Type Ia supernovae (SNe Ia) obtained by the Nearby Supernova Factory. These SNe are identified by examining 346 spectra from 124 SNe obtained before +2.5 days relative to maximum. Detections are based on the presence of relatively strong C II ?6580 absorption "notches" in multiple spectra of each SN, aided by automated fitting with the SYNAPPS code. Four of the five SNe in question are otherwise spectroscopically unremarkable, with ions and ejection velocities typical of SNe Ia, but spectra of the fifth exhibit high-velocity (v > 20, 000 km s-1) Si II and Ca II features. On the other hand, the light curve properties are preferentially grouped, strongly suggesting a connection between carbon-positivity and broadband light curve/color behavior: three of the five have relatively narrow light curves but also blue colors and a fourth may be a dust-reddened member of this family. Accounting for signal to noise and phase, we estimate that 22+10 - 6% of SNe Ia exhibit spectroscopic C II signatures as late as -5 days with respect to maximum. We place these new objects in the context of previously recognized carbon-positive SNe Ia and consider reasonable scenarios seeking to explain a physical connection between light curve properties and the presence of photospheric carbon. We also examine the detailed evolution of the detected carbon signatures and the surrounding wavelength regions to shed light on the distribution of carbon in the ejecta. Our ability to reconstruct the C II ?6580 feature in detail under the assumption of purely spherical symmetry casts doubt on a "carbon blobs" hypothesis, but does not rule out all asymmetric models. A low volume filling factor for carbon, combined with line-of-sight effects, seems unlikely to explain the scarcity of detected carbon in SNe Ia by itself.

Thomas, R. C.; Aldering, G.; Antilogus, P.; Aragon, C.; Bailey, S.; Baltay, C.; Bongard, S.; Buton, C.; Canto, A.; Childress, M.; Chotard, N.; Copin, Y.; Fakhouri, H. K.; Gangler, E.; Hsiao, E. Y.; Kerschhaggl, M.; Kowalski, M.; Loken, S.; Nugent, P.; Paech, K.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigault, M.; Rubin, D.; Runge, K.; Scalzo, R.; Smadja, G.; Tao, C.; Weaver, B. A.; Wu, C.; Brown, P. J.; Milne, P. A.; Nearby Supernova Factory

2011-12-01

488

Carbon dioxide adsorption on nanomaterials  

NASA Astrophysics Data System (ADS)

In this study, CO2 adsorption in the presence and absence of co-adsorbed H2O was investigated on different nanomaterials including nanocrystalline NaY zeolite (nano NaY), ZnO, MgO and gamma-Al 2O3 nanoparticles as well as mixed phase aluminum nanowhiskers. In the case of nano NaY, FTIR spectra show that a majority of CO2 adsorbs in the pores of these zeolites in a linear complex with the exchangeable cation. Most interesting is the formation of carbonate and bicarbonate on the external surface of nano NaY zeolites, suggesting unique sites for CO 2 adsorption on the surface of these small nanomaterials. Adsorption of 18O-labeled carbon dioxide and theoretical quantum chemical calculations confirms the assignment of these different species. For aluminum oxyhydroxide nanowhiskers and gamma alumina in the absence of co-adsorbed water, CO2 reacts with surface hydroxyl groups to yield adsorbed bicarbonate as well as some carbonate. C18O2 adsorption confirms these assignments. In the case of nanoparticulate ZnO, CO2 adsorption under dry conditions results in formation of carbonate, bicarbonates as well as carboxylates. However, in the presence of co-adsorbed water, only carbonate species is formed. 18O-labeled carbon dioxide adsorption and theoretical quantum chemical calculations confirm the vibrational assignment for these different species. Mixed isotope studies with H2 16O + C18O2 and H2 18O + C16O2 suggest that there is extensive exchange between oxygen in adsorbed water and oxygen atoms in gas-phase carbon dioxide. CO2 adsorption on MgO surfaces, under dry conditions results in formation of carbonate and bicarbonates. Implications for the use of these nanomaterials in carbon dioxide uptake and storage are discussed.

Galhotra, Pragati

489

Current and relic carbon using natural abundance carbon-13  

SciTech Connect

The role of agricultural practices on soil carbon (C) dynamics is critical to improved soil management. The main objective was to examine the C interactions resulting from crop changes under different tillage and residue treatments.

layse,MF; Clapp,CE; Allmaras,RR; Linden,D.R; Molina, JAE.; Copeland,SM; Dowdy,RH

2002-05-01

490

Inhibition of catalytic oxidation of carbon/carbon composite materials  

NASA Astrophysics Data System (ADS)

An investigation coupling experimental efforts with computational chemistry analysis was conducted to study the inhibition effects of phosphorous or boron on the oxidation of carbon/carbon composite materials catalyzed by potassium or calcium acetate (KAC or CaAC). Commercial aircraft brakes were used, which are exposed during use to K- or Ca-containing runway deicing agents. The reactivity of inhibitor-doped carbon materials was determined by temperature programmed oxidation (TPO) and isothermal oxidation in 1 atm O2. The structure and surface chemistry of inhibitor-doped samples were characterized, and the inhibition mechanisms were explored with the help of ab initio molecular orbital calculations. The catalytic effects of KAC or CaAC were found to be dependent on catalyst loading, pretreatment procedure, temperature and O2 partial pressure. Experimental observations showed that K is a more effective catalyst for carbon composite oxidation than Ca as expected from prior studies of catalyzed carbon gasification. This was attributed to its ability to form and maintain good interfacial contact with carbon, as well as to its insensitivity to carbon structure because of its excellent wetting ability and mobility. The experimental results suggested that the interfacial catalyst/carbon contact is the critical factor determining the catalytic effectiveness. Thermally deposited phosphorus, upon heat treatment of P-containing compounds such as CH3OP(OH)2 and POCl3 at around 600C in the presence of inert gas, exhibited a good inhibition effect in the oxidation of C/C composites used in aircraft brake systems. These P compounds were also effective inhibitors for Ca- or K-catalyzed oxidation. The P loading up to a certain amount (ca. 4.0 wt%) was found to suppress Ca-catalyzed oxidation completely. It also improved the resistance of carbon to K-catalyzed oxidation, but the effect was much less significant than in the case of Ca-catalyzed reaction. The characterization of P-doped carbon samples by XPS, XRD, SEM and TPD and the theoretical explorations by ab initio molecular orbital calculations showed that P doping had no effect on the carbon structure and that oxygen-containing P groups preferentially block the active sites on the carbon surface, thus being responsible for the inhibition effect. Boron doping of the composites at 2500C was found to have a strong inhibition effect in Ca-catalyzed carbon oxidation and a weak effect in K-catalyzed oxidation. Boron as a dopant was confirmed, by XRD, to enhance the graphitization of the composites. The XPS results supported that the chemical state of doped boron is substitutional, that it is oxidized during carbon oxidation, and that it remains on the carbon surface as boron oxide. The substitutional boron and its oxide appear to have a strong effect on the interfacial contact between the carbon substrate and the catalysts. Accordingly, the catalytic effect of Ca can be almost completely suppressed. (Abstract shortened by UMI.)

Wu, Xianxian

491

Molecular Structure of Carbon tetrachloride  

NSDL National Science Digital Library

Carbon tetrachloride was first prepared in 1839. It was discovered by German-born French scientist Henri Victor Regnault during his work with ether/chlorine reactions. Carbon tetrachloride is a clear, heavy, poisonous, nonflammable liquid with a strong ethereal odor. It is also fairly common as a colorless gas. Carbon tetrachloride is used for dry cleaning, degreasing metals, fumigating, manufacturing refrigerants and aerosol propellants, and is also used in fire extinguishers. CCl4 is a possible carcinogen; inhalation or ingestion can cause damage to the brain, liver, kidneys, and can even cause death. CCl4 also contributes to ozone layer depletion.

2002-08-15

492

Photoinduced oxidation of carbon nanotubes  

NASA Astrophysics Data System (ADS)

Photoinduced phenomena are of general interest for new materials. Recently, photoinduced molecular desorption of oxygen has been reported in carbon nanotubes. Here we present, using thermopower measurements, that carbon nanotubes when exposed simultaneously to UV light and oxygen exhibit photoinduced oxidation of the nanotubes. At least two plausible mechanisms for the experimentally observed photoinduced oxidation are proposed: (i) a lower energy barrier for the adsorption of photo-generated singlet oxygen, or (ii) due to the presence of defects in carbon nanotubes that may facilitate the formation of locally electron-deficient and electron-rich regions on the nanotubes which facilitate the adsorption of oxygen molecules on the nanotubes.

Savage, T.; Bhattacharya, S.; Sadanadan, B.; Gaillard, J.; Tritt, T. M.; Sun, Y.-P.; Wu, Y.; Nayak, S.; Car, R.; Marzari, N.; Ajayan, P. M.; Rao, A. M.

2003-09-01

493

Recalcitrant dissolved organic carbon fractions.  

PubMed

Marine dissolved organic carbon (DOC) exhibits a spectrum of reactivity, from very fast turnover of the most bioavailable forms in the surface ocean to long-lived materials circulating within the ocean abyss. These disparate reactivities group DOC by fractions with distinctive functions in the cycling of carbon, ranging from support of the microbial loop to involvement in the biological pump to a hypothesized major source/sink of atmospheric CO(2) driving paleoclimate variability. Here, the major fractions constituting the global ocean's recalcitrant DOC pool are quantitatively and qualitatively characterized with reference to their roles in carbon biogeochemistry. A nomenclature for the fractions is proposed based on those roles. PMID:22881353

Hansell, Dennis A

2012-07-16

494

Thermoelectric power in carbon nanotubes  

SciTech Connect

The theoretical results for the temperature dependence of the thermoelectric power of graphite and semimetal carbon nanotubes are reported. In the calculations, the cylindrical superatomic range structure of nanotubes is taken into account. The Boltzmann equation and the {pi}-electron model of semimetal carbon nanotubes are used. The basic parameters of the calculation are the concentration of electrons, the Fermi energy, and the energy of the local level associated with the cylindrical structure of carbon nanotubes. The theoretical results are compared with the available experimental data.

Mavrinskiy, A. V., E-mail: mavrinsky@gmail.com; Baitinger, E. M. [Chelyabinsk State Pedagogical University (Russian Federation)

2009-04-15

495

Nanomachines based on carbon nanotubes  

NASA Astrophysics Data System (ADS)

The possibility for double-wall carbon nanotube to operate as the bolt and nut pair is studied. The barriers for relative motions of walls along the helical ``thread'' line and for jumps on neighbor helical lines are calculated as functions of wall lengths for the set of double-wall carbon nanotubes. The dynamics of relative motion of carbon nanotube walls along the helical line under the action of external forces is considered. Perforated nanodrill, variable nanoresistor and other nanotube based mechanical nanodevices using these motion are proposed. Possible operation modes of proposed nanodevices are discussed.

Lozovik, Yu. E.; Minogin, A. V.; Popov, A. M.

2003-06-01

496

The fate of carbon in grasslands under carbon dioxide enrichment  

Microsoft Academic Search

The concentration of carbon dioxide (CO2) in the Earth's atmosphere is rising rapidly, with the potential to alter many ecosystem processes. Elevated CO2 often stimulates photosynthesis, creating the possibility that the terrestrial biosphere will sequester carbon in response to rising atmospheric CO2 concentration, partly offsetting emissions from fossil-fuel combustion, cement manufacture, and deforestation,. However, the responses of intact ecosystems to

Bruce A. Hungate; Elisabeth A. Holland; Robert B. Jackson; F. Stuart Chapin; Harold A. Mooney; Christopher B. Field

1997-01-01

497

Thermal decomposition kinetics of amorphous carbon nitride and carbon films  

Microsoft Academic Search

Kinetic thermal degradation of amorphous carbon and carbon nitride films is studied. Significantly improved thermal stability was observed for films intensified with C-N, C=N, and C?N bonds. When the N2% (percentage of nitrogen) in Ar\\/N2 during film deposition was varied from 0 to 30 at pressures of 310-3 and 1610-3 Torr, the onset decomposition temperatures increased from 396 to 538

Li Hong Zhang; Hao Gong; Jian Ping Wang

2002-01-01

498

Carbon emission trading and carbon taxes under uncertainties  

Microsoft Academic Search

The idea of market-based carbon emission trading and carbon taxes is gaining in popularity as a global climate change policy\\u000a instrument. However, these mechanisms might not necessarily have a positive outcome unless their value reflects socioeconomic\\u000a and environmental impacts and regulations. Moreover, the fact that they have various inherent exogenous and endogenous uncertainties\\u000a raises serious concerns about their ability to

Tatiana Ermolieva; Yuri Ermoliev; Gnther Fischer; Matthias Jonas; Marek Makowski; Fabian Wagner

2010-01-01

499

Carbon emission trading and carbon taxes under uncertainties  

Microsoft Academic Search

\\u000a The idea of market-based carbon emission trading and carbon taxes is gaining in popularity as a global climate change policy\\u000a instrument. However, these mechanisms might not necessarily have a positive outcome unless their value reflects socioeconomic\\u000a and environmental impacts and regulations. Moreover, the fact that they have various inherent exogenous and endogenous uncertainties\\u000a raises serious concerns about their ability to

Tatiana Ermolieva; Yuri Ermoliev; Gnther Fischer; Matthias Jonas; Marek Makowski; Fabian Wagner

500

Adsorption of tetrachloride carbon on microporous APB carbon sorbent  

Microsoft Academic Search

The adsorption isotherms of tetrachloride carbon on microporous AP-B carbon adsorbent are measured and the differential isosteric\\u000a heats of adsorption over the pressure range of 114 000 Pa at temperatures of 255.5352.8 K are calculated. The adsorption\\u000a isotherms with increasing temperature almost symbatically shift toward higher pressures and have an adsorption hysteresis\\u000a loop in the range of high adsorption values

V. V. Nabiulin; A. A. Fomkin; A. V. Tvardovskiy

2011-01-01