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Sample records for carbon gac enhanced

  1. Practical experiences with granular activated carbon (GAC) at the ...

    African Journals Online (AJOL)

    driniev

    2004-01-01

    Jan 1, 2004 ... to measure the GAC performance at full-scale. After verification that the GAC ... The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that ... carbon (GAC) and ozone possibilities were investigated. His results indicated that an ...

  2. GAC

    CERN Multimedia

    GAC

    2014-01-01

          GAC-EPA Groupement des Anciens CERN-ESO Pensioners’ Association Association du Personnel du CERN CH-1211 GENEVE 23 e-mail : http://gac-epa@gac-epa.org web : http://www.gac-epa.org Nous vous annonçons que l’Assemblée générale ordinaire 2014 du GAC aura lieu le mercredi 26 mars 2014 à 14h00 à l’Amphithéâtre principal du CERN, bâtiment 60.

  3. Practical experiences with granular activated carbon (GAC) at the ...

    African Journals Online (AJOL)

    Practical experiences with granular activated carbon (GAC) at the Rietvlei Water Treatment Plant. ... Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of ...

  4. GAC

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 8 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. * * * * * Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  5. GAC

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 7 septembre de 13h30 à 16h00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   * * * * * Nous avons appris avec tristesse les décès de : M. Gianfalco POZZO (1926), décédé le 30.06.10. Il avait pris sa retraite en 1991 (ex-division PPE). Il laisse une veuve : ...

  6. Granular Activated Carbon (GAC) System Performance Capabilities and Optimization

    Science.gov (United States)

    1987-02-27

    adsorbent for organics. Adsorption theory is that organic molecules are attracted to a carbon surface by Van der Waals (non- bonded) forces. The...8217.€. . @ .’j :£ .’.’ 2 ’ .’ : 2 5 Fran Drop 4010 a GAC Men Size TOWVh WITCARI 90 13.x40 200C gFILTWUASS 200 12.x40 186C ILTUASOIS 400 12.40 *C // //YD.’,ODAMCO

  7. Fractional Factorial Design Study on the Performance of GAC-Enhanced Electrocoagulation Process Involved in Color Removal from Dye Solutions

    Directory of Open Access Journals (Sweden)

    Iuliana Gabriela Breaban

    2013-07-01

    Full Text Available The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC. In this study, a mathematical approach was conducted using a two-level fractional factorial design (FFD for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m2, initial pH of aqueous dye solution (3 or 9, electrocoagulation time (20 or 180 min, GAC dose (0.1 or 0.5 g/L, support electrolyte (2 or 50 mM, initial dye concentration (0.05 or 0.25 g/L and current type (Direct Current—DC or Alternative Pulsed Current—APC. GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method.

  8. Removing 17β-estradiol from drinking water in a biologically active carbon (BAC) reactor modified from a granular activated carbon (GAC) reactor.

    Science.gov (United States)

    Li, Zhongtian; Dvorak, Bruce; Li, Xu

    2012-06-01

    Estrogenic compounds in drinking water sources pose potential threats to human health. Treatment technologies are needed to effectively remove these compounds for the production of safe drinking water. In this study, GAC adsorption was first tested for its ability to remove a model estrogenic compound, 17β-estradiol (E2). Although GAC showed a relatively high adsorption capacity for E2 in isotherm experiments, it appeared to have a long mass transfer zone in a GAC column reactor, causing an early leakage of E2 in the effluent. With an influent E2 concentration of 20 μg/L, the GAC reactor was able to bring down effluent E2 to ≈ 200 ng/L. To further enhance E2 removal, the GAC reactor was converted to a biologically active carbon (BAC) reactor by promoting biofilm growth in the reactor. Under optimal operating conditions, the BAC reactor had an effluent E2 concentration of ≈ 50 ng/L. With the empty bed contact times tested, the reactor exhibited more robust E2 removal performance under the BAC operation than under the GAC operation. It is noted that estrone (E1), an E2 biodegradation intermediate, was frequently detected in reactor effluent during the BAC operation. Results from this study suggested that BAC could be an effective drinking water treatment process for E2 removal and in the meantime E1 accumulation needs to be addressed. Published by Elsevier Ltd.

  9. Development of biomass in a drinking water granular active carbon (GAC) filter.

    Science.gov (United States)

    Velten, Silvana; Boller, Markus; Köster, Oliver; Helbing, Jakob; Weilenmann, Hans-Ulrich; Hammes, Frederik

    2011-12-01

    Indigenous bacteria are essential for the performance of drinking water biofilters, yet this biological component remains poorly characterized. In the present study we followed biofilm formation and development in a granular activated carbon (GAC) filter on pilot-scale during the first six months of operation. GAC particles were sampled from four different depths (10, 45, 80 and 115 cm) and attached biomass was measured with adenosine tri-phosphate (ATP) analysis. The attached biomass accumulated rapidly on the GAC particles throughout all levels in the filter during the first 90 days of operation and maintained a steady state afterward. Vertical gradients of biomass density and growth rates were observed during start-up and also in steady state. During steady state, biomass concentrations ranged between 0.8-1.83 x 10(-6) g ATP/g GAC in the filter, and 22% of the influent dissolved organic carbon (DOC) was removed. Concomitant biomass production was about 1.8 × 10(12) cells/m(2)h, which represents a yield of 1.26 × 10(6) cells/μg. The bacteria assimilated only about 3% of the removed carbon as biomass. At one point during the operational period, a natural 5-fold increase in the influent phytoplankton concentration occurred. As a result, influent assimilable organic carbon concentrations increased and suspended bacteria in the filter effluent increased 3-fold as the direct consequence of increased growth in the biofilter. This study shows that the combination of different analytical methods allows detailed quantification of the microbiological activity in drinking water biofilters. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. The Sensor Kinase GacS Negatively Regulates Flagellar Formation and Motility in a Biocontrol Bacterium, Pseudomonas chlororaphis O6

    Directory of Open Access Journals (Sweden)

    Ji Soo Kim

    2014-06-01

    Full Text Available The GacS/GacA two component system regulates various traits related to the biocontrol potential of plant-associated pseudomonads. The role of the sensor kinase, GacS, differs between strains in regulation of motility. In this study, we determined how a gacS mutation changed cell morphology and motility in Pseudomonas chlororaphis O6. The gacS mutant cells were elongated in stationary-phase compared to the wild type and the complemented gacS mutant, but cells did not differ in length in logarithmic phase. The gacS mutant had a two-fold increase in the number of flagella compared with the wild type strain; flagella number was restored to that of the wild type in the complemented gacS mutant. The more highly flagellated gacS mutant cells had greater swimming motilities than that of the wild type strain. Enhanced flagella formation in the gacS mutant correlated with increased expression of three genes, fleQ, fliQ and flhF, involved in flagellar formation. Expression of these genes in the complemented gacS mutant was similar to that of the wild type. These findings show that this root-colonizing pseudomonad adjusts flagella formation and cell morphology in stationary-phase using GacS as a major regulator.

  11. Enhanced activation of periodate by iodine-doped granular activated carbon for organic contaminant degradation.

    Science.gov (United States)

    Li, Xiaowan; Liu, Xitao; Lin, Chunye; Qi, Chengdu; Zhang, Huijuan; Ma, Jun

    2017-08-01

    In this study, iodine-doped granular activated carbon (I-GAC) was prepared and subsequently applied to activate periodate (IO4(-)) to degrade organic contaminants at ambient temperature. The physicochemical properties of GAC and I-GAC were examined using scanning electron microscopy, N2 adsorption/desorption, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. No significant difference was observed between the two except for the existence of triiodide (I3(-)) and pentaiodide (I5(-)) on I-GAC. The catalytic activity of I-GAC towards IO4(-) was evaluated by the degradation of acid orange 7 (AO7), and superior catalytic performance was achieved compared with GAC. The effects of some influential parameters (preparation conditions, initial solution pH, and coexisting anions) on the catalytic ability were also investigated. Based on radical scavenging experiments, it appeared that IO3 was the predominant reactive species in the I-GAC/IO4(-) system. The mechanism underlying the enhanced catalytic performance of I-GAC could be explained by the introduction of negatively charged I3(-) and I5(-) into I-GAC, which induced positive charge density on the surface of I-GAC. This accelerated the interaction between I-GAC and IO4(-), and subsequently mediated the increasing generation of iodyl radicals (IO3). Furthermore, a possible degradation pathway of AO7 was proposed according to the intermediate products identified by gas chromatography-mass spectrometry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Degradation of 3,3'-iminobis-propanenitrile in aqueous solution by Fe(0)/GAC micro-electrolysis system.

    Science.gov (United States)

    Lai, Bo; Zhou, Yuexi; Yang, Ping; Yang, Jinghui; Wang, Juling

    2013-01-01

    The degradation of 3,3'-iminobis-propanenitrile was investigated using the Fe(0)/GAC micro-electrolysis system. Effects of influent pH value, Fe(0)/GAC ratio and granular activated carbon (GAC) adsorption on the removal efficiency of the pollutant were studied in the Fe(0)/GAC micro-electrolysis system. The degradation of 3,3'-iminobis-propanenitrile was affected by influent pH, and a decrease of the influent pH values from 8.0 to 4.0 led to the increase of degradation efficiency. Granular activated carbon was added as cathode to form macroscopic galvanic cells between Fe(0) and GAC and enhance the current efficiency of the Fe(0)/GAC micro-electrolysis system. The GAC could only adsorb the pollutant and provide buffer capacity for the Fe(0)/GAC micro-electrolysis system, and the macroscopic galvanic cells of the Fe(0)/GAC micro-electrolysis system played a leading role in degradation of 3,3'-iminobis-propanenitrile. With the analysis of the degradation products with GC-MS, possible reaction pathway for the degradation of 3,3'-iminobis-propanenitrile by the Fe(0)/GAC micro-electrolysis system was suggested. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Treatability studies with granular activated carbon (GAC) and sequencing batch reactor (SBR) system for textile wastewater containing direct dyes

    Energy Technology Data Exchange (ETDEWEB)

    Sirianuntapiboon, Suntud [Department of Environmental Technology, School of Energy Environment and Materials, King Mongkut' s University of Technology, Thonburi, Bangmod, Thung-kru, Bangkok 10140 (Thailand)], E-mail: suntud.sir@kmutt.ac.th; Sansak, Jutarat [Department of Environmental Technology, School of Energy Environment and Materials, King Mongkut' s University of Technology, Thonburi, Bangmod, Thung-kru, Bangkok 10140 (Thailand)

    2008-11-30

    The GAC-SBR efficiency was decreased with the increase of dyestuff concentration or the decrease of bio-sludge concentration. The system showed the highest removal efficiency with synthetic textile wastewater (STWW) containing 40 mg/L direct red 23 or direct blue 201 under MLSS of 3000 mg/L and hydraulic retention time (HRT) of 7.5 days. But, the effluent NO{sub 3}{sup -} was higher than that of the influent. Direct red 23 was more effective than direct blue 201 to repress the GAC-SBR system efficiency. The dyes removal efficiency of the system with STWW containing direct red 23 was reduced by 30% with the increase of direct red 23 from 40 mg/L to 160 mg/L. The system with raw textile wastewater (TWW) showed quite low BOD{sub 5} TKN and dye removal efficiencies of only 64.7 {+-} 4.9% and 50.2 {+-} 6.9%, respectively. But its' efficiencies could be increased by adding carbon sources (BOD{sub 5}). The dye removal efficiency with TWW was increased by 30% and 20% by adding glucose (TWW + glucose) or Thai rice noodle wastewater (TWW + TRNWW), respectively. SRT of the systems were 28 {+-} 1 days and 31 {+-} 2 days with TWW + glucose and TWW + TRNWW, respectively.

  14. Graphene-modified Pd/C cathode and Pd/GAC particles for enhanced electrocatalytic removal of bromate in a continuous three-dimensional electrochemical reactor.

    Science.gov (United States)

    Mao, Ran; Zhao, Xu; Lan, Huachun; Liu, Huijuan; Qu, Jiuhui

    2015-06-15

    Bromate (BrO3(-)) is a carcinogenic and genotoxic contaminant commonly generated during ozonation of bromide-containing water. In this work, the reductive removal of BrO3(-) in a continuous three-dimensional electrochemical reactor with palladium-reduced graphene oxide modified carbon paper (Pd-rGO/C) cathode and Pd-rGO modified granular activated carbon (Pd-rGO/GAC) particles was investigated. The results indicated that the rGO sheets significantly promoted the electrochemical reduction of BrO3(-). With the enhanced electron transfer by rGO sheets, the electroreduction of H2O to atomic H* on the polarized Pd particles could be significantly accelerated, leading to a faster reaction rate of BrO3(-) with atomic H*. The synergistic effect of the Pd-rGO/C cathode and Pd-rGO/GAC particles were also exhibited. The atomic H* involved in various electroreduction processes was detected by electron spin resonance spectroscopy and its role for BrO3(-) reduction was determined. The performance of the reactor was evaluated in terms of the removal of BrO3(-) and the yield of Br(-) as a function of the GO concentration, Pd loading amount, current density, hydraulic residence time (HRT), and initial BrO3(-) concentration. Under the current density of 0.9 mA/cm(2), BrO3(-) with the initial concentration of 20 μg/L was reduced to be less than 6.6 μg/L at the HRT of 20 min. The BrO3(-) reduction was inhibited in the presence of dissolved organic matter. Although the precipitates generated from Ca(2+) and Mg(2+) in the tap water would cover the Pd catalysts, a long-lasting electrocatalytic activity could be maintained for the 30 d treatment. SEM and XPS analysis demonstrated that the precipitates were predominantly deposited onto the Pd-rGO/C cathode rather than the Pd-rGO/GAC particles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    It saddens us deeply to learn of the passing away of Jean-Paul Diss who died suddenly on 7 June 2012 at his home.  A tribute can be read on the GAC-EPA site. * * * * * Information: http://gac-epa.org/ e-mail: gac-epa@gac-epa.org

  16. Sustainable Regeneration of Nanoparticle Enhanced Activated Carbon in Water

    Science.gov (United States)

    The regeneration and reuse of exhausted granular activated carbon (GAC) is an appropriate method for lowering operational and environmental costs. Advanced oxidation is a promising environmental friendly technique for GAC regeneration. The main objective of this research was to ...

  17. Adsorption / reduction of bromate from drinking water using GAC ...

    African Journals Online (AJOL)

    This study investigated the feasibility of using granular activated carbon (GAC) to remove bromate (BrO3-) from drinking water through batch experiments, rapid small-scale column tests (RSSCT) and a pilot-scale study. The results indicated that the GAC capacity for BrO3- removal was dependent on the GAC surface ...

  18. EFFECTS OF PRETREATMENTS ON CALCIUM ACCUMULATION ONTO GAC

    OpenAIRE

    Miño, Esteban R.; Okuda, Tetsuji; NISHIJIMA, Wataru; OKADA, Mitsumasa

    2007-01-01

    The effect of coagulation and ozonation as pretreatments for granular activated carbon (GAC) filtration on calcium accumulation onto GAC was studied. Three kinds of FA solutions extracted from commercial leaf mold for horticulture were used: FA itself, FA after coagulation (FA-c) and FA after ozonation (FA-oz). Coagulation used as pretreatment before GAC filtration significantly decreased calcium accumulation onto GAC while ozonation caused a small increase on calcium accumulation onto GA...

  19. Removal efficiency of multiple poly- and perfluoroalkyl substances (PFASs) in drinking water using granular activated carbon (GAC) and anion exchange (AE) column tests.

    Science.gov (United States)

    McCleaf, Philip; Englund, Sophie; Östlund, Anna; Lindegren, Klara; Wiberg, Karin; Ahrens, Lutz

    2017-09-01

    Poly- and perfluoroalkyl substances (PFASs) have been detected in drinking water at relatively high concentrations throughout the world which has led to implementation of regulatory guidelines for specific PFASs in drinking water in several European countries and in the U.S. The Swedish National Food Agency has determined that the drinking water of over one third of the country's municipal consumers is at risk or already affected by PFAS contamination. The present study investigated the effects of perfluorocarbon chain length, functional group and isomer structure (branched or linear) on removal of multiple PFASs using granular activated carbon (GAC, Filtrasorb ® 400) and anion exchange (AE, Purolite ® A600) column experiments. The removal of 14 different PFASs, i.e. the C 3 C 11 , C 14 perfluoroalkyl carboxylic acids (PFCAs) (PFBA, PFPeA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnDA, PFDoDA, PFTeDA), perfluorooctane sulfonamide (FOSA), and the C 4 , C 6 , C 8 perfluoroalkyl sulfonic acids (PFSAs) (PFBS, PFHxS, PFOS), was monitored for a 217 day period. The results indicate the selective nature of PFAS removal as the absorbents are loaded with PFASs and dissolved organic carbon (DOC). A clear relationship between perfluorocarbon chain length and removal efficiency of PFASs using GAC and AE was found while PFASs with sulfonate functional groups displayed greater removal efficiency than those with carboxylate groups. Similarly, time to column breakthrough increased with increasing perfluorocarbon chain length and was greater for the PFSAs than the PFCAs for both GAC and AE. Shorter carbon chained PFASs such as PFBA, PFPeA, PFHxA showed desorption behavior and long-chained PFASs showed increased removal towards the end of the experiment indicating agglomeration or micelle development. Linear isomers of PFOS, PFHxS, and perfluorooctane sulfonamide (FOSA) had greater column removal efficiencies using GAC (and also for AE at greater bed volume throughput) than the branched

  20. Promoting direct interspecies electron transfer with activated carbon

    DEFF Research Database (Denmark)

    Liu, Fanghua; Rotaru, Amelia-Elena; Shrestha, Pravin M.

    2012-01-01

    Granular activated carbon (GAC) is added to methanogenic digesters to enhance conversion of wastes to methane, but the mechanism(s) for GAC’s stimulatory effect are poorly understood. GAC has high electrical conductivity and thus it was hypothesized that one mechanism for GAC stimulation...

  1. Iron Amendment and Fenton Oxidation of MTBE-Spent Granular Activated Carbon

    Science.gov (United States)

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves Fe amendment to the GAC to catalyze H2O2 reactions and to enhance the rate of MTBE oxidation and GAC regeneration. Four forms of iron (ferric sulfate, ferric chloride, fer...

  2. Enhanced desalination performance of membrane capacitive deionization cells by packing the flow chamber with granular activated carbon.

    Science.gov (United States)

    Bian, Yanhong; Yang, Xufei; Liang, Peng; Jiang, Yong; Zhang, Changyong; Huang, Xia

    2015-11-15

    A new design of membrane capacitive deionization (MCDI) cell was constructed by packing the cell's flow chamber with granular activated carbon (GAC). The GAC packed-MCDI (GAC-MCDI) delivered higher (1.2-2.5 times) desalination rates than the regular MCDI at all test NaCl concentrations (∼ 100-1000 mg/L). The greatest performance enhancement by packed GAC was observed when treating saline water with an initial NaCl concentration of 100 mg/L. Several different GAC materials were tested and they all exhibited similar enhancement effects. Comparatively, packing the MCDI's flow chamber with glass beads (GB; non-conductive) and graphite granules (GG; conductive but with lower specific surface area than GAC) resulted in inferior desalination performance. Electrochemical impedance spectroscopy (EIS) analysis showed that the GAC-MCDI had considerably smaller internal resistance than the regular MCDI (∼ 19.2 ± 1.2 Ω versus ∼ 1222 ± 15 Ω at 100 mg/L NaCl). The packed GAC also decreased the ionic resistance across the flow chamber (∼ 1.49 ± 0.05 Ω versus ∼ 1130 ± 12 Ω at 100 mg/L NaCl). The electric double layer (EDL) formed on the GAC surface was considered to store salt ions during electrosorption, and facilitate the ion transport in the flow chamber because of the higher ion conductivity in the EDLs than in the bulk solution, thereby enhancing the MCDI's desalination rate. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Bacterial community in the biofilm of granular activated carbon (GAC) PreBiofilter in bench-scale pilot plants for surface water pretreatment.

    Science.gov (United States)

    Wu, Tiehang; Fu, George Yuzhu; Sabula, Michael; Brown, Tommy

    2014-12-01

    Biofilters of granular activated carbon (GAC) are responsible for the removal of organic matters in drinking water treatments. PreBiofilters, which operate as the first unit in a surface water treatment train, are a cost-effective pretreatment for conventional surface water treatment and provide more consistent downstream water quality. This study investigated bacterial communities from the samples of raw surface water, biofilm on the PreBiofilter, and filtrates for surface water pretreatment. A bench-scale pilot plant of PreBiofilter was constructed to pretreat surface water from the Canoochee River, GA, USA. PreBiofilter exhibited a significant reduction of total organic carbon and dissolved organic carbon. The evenness and Shannon diversity of bacterial operational taxonomic units (OTUs) were significantly higher on the biofilm of PreBiofilter than in raw water and filtrates. Similar bacteria communities were observed in the raw water and filtrates using relative abundance of bacterial OTUs. However, the bacterial communities in the filtrates became relatively similar to those in the biofilm using presence/absence of bacterial OTUs. GAC biofilm or raw water and filtrates greatly contributed to the abundance of bacteria; whereas, bacteria sheared from colonized biofilm and entered filtrates. Evenly distributed, diverse and unique bacteria in the biofilm played an important role to remove organic matters from surface water for conventional surface water pretreatment.

  4. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 7 avril, 5 mai, 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2013. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  5. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 1er octobre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 novembre et 3 décembre 2013. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  6. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel La permanence suivante aura lieu le mardi 3 décembre 2013. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  7. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 décembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  8. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 7 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ e-mail : gac-epa@gac-epa.org

  9. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 7 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 mai, 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2013. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  10. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  11. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 3 mai, 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre décembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  12. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 1er mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 avril, 3 mai, 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  13. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : le mardi 29 novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  14. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er mars, 5 avril, 3 mai, 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  15. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 1er décembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  16. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre décembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  17. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 juin de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  18. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 4 octobre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  19. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 3 mai, 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  20. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : le mardi 1er novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. La permanence suivante aura lieu le mardi 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  1. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel La permanence suivante aura lieu le mardi 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  2. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 8 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. * * * * * Informations : http://gac-epa.org/ e-mail : gac-epa@gac-epa.org

  3. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2014-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 4 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org. * * * * * Carte de membre de l'Association du personnel du CERN Les membres GAC-EPA qui souhaitent recevoir une carte de membre AP en 2014 doivent  en faire la demande par email à secretariat@gac-epa.org, ou par lettre au secrétaire ...

  4. Enhancing zero valent iron based natural organic matter removal by mixing with dispersed carbon cathodes.

    Science.gov (United States)

    Liu, Peng; Keller, Jurg; Gernjak, Wolfgang

    2016-04-15

    Former studies have shown that adding granular activated carbon (GAC) cathodes could enhance the overall performance of the zero valent iron (ZVI) process for organics removal. The present study evaluates for the first time the performance of such an enhanced ZVI process to remove natural organic matter (NOM), an important water quality parameter in drinking water. Lab-scale batch tests were conducted with surface reservoir feed water from a drinking water plant. In the GAC enhanced ZVI process dissolved organic carbon (DOC) and UV254 were reduced by 61±3% and 70±2%, respectively, during 24h treatment corresponding to 1.8min empty bed contact time. The process was superior to ZVI alone, particularly during the earlier stages of the process due to the synergistically increased iron dissolution rate. Besides GAC, graphite and anthracite also prove to be suitable and potentially more cost-effective options as cathode materials for the enhanced ZVI process, whereby electrically conductive graphite clearly outperformed anthracite. The dominant mechanisms in terms of NOM removal from surface water were found to be coagulation following iron dissolution and adsorption in the case of employing GAC. Oxidation was also occurring to a lesser degree, converting some non-biodegradable into biodegradable DOC. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 1er novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel La permanence suivante aura lieu le mardi 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php  

  6. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 31 octobre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel La permanence suivante aura lieu le mardi 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  7. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 26 septembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  8. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 28 novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  9. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 30 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  10. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 29 août de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/ Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php  

  11. GAC-EPA

    CERN Multimedia

    GAC-EPA

    GROUPEMENT DES ANCIENS DU CERN ESO PENSIONERS’S ASSOCIATION Le GAC-EPA organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 1er décembre de 13 h 30 à 16 h 00 Salle de conférence de l’Association du personnel Les permanences du GAC-EPA sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. http://www.gac-epa.org

  12. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    Carte de membre de l'Association du personnel du CERN Comme cela a été précisé dans le bulletin d'automne n° 43, les membres GAC-EPA qui souhaitent recevoir une carte de membre AP en 2013 devront en faire la demande, avant le 31 janvier, par email à secretariat@gac-epa.org, ou par lettre au secrétaire du GAC-EPA, p/a Association du personnel CERN, CH-1211 GENEVE 23. Il n'y a pas de tacite reconduction de ces cartes et par conséquent une demande doit être faite chaque année par l'intéressé(e).

  13. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 31 janvier de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 28 février, 28 mars, 25 avril, 30 mai, 29 août, 26 septembre, 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. e-mail : gac-epa@gac-epa.org.

  14. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 30 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 29 août, 26 septembre, 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  15. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 28 mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 25 avril, 30 mai, 29 août, 26 septembre, 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  16. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 28 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 28 mars, 25 avril, 30 mai, 29 août, 26 septembre, 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  17. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2017-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 25 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 30 mai, 29 août, 26 septembre, 31 octobre et 28 novembre 2017. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Informations : http://gac-epa.org/. Formulaire de contact : http://gac-epa.org/Organization/ContactForm/ContactForm-fr.php

  18. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.     René Oberli 1930 – 2011 Nous avons le regret  de vous annoncer le décès de notre collègue et ami René Oberli survenu le 24 décembre 2011. Vous trouverez un hommage sur le site web du GAC-EPA sous http://www.gac-epa.org/History/Tributes/2011/Ren...

  19. Developing and Validating a Rapid Small-Scale Column Test Procedure for GAC Selection using Reconstituted Lyophilized NOM

    Science.gov (United States)

    Cost effective design and operation of Granular Activated Carbon (GAC) facilities requires the selection of GAC that is optimal for a specific site. Rapid small-scale column tests (RSSCTs) are widely used for GAC assessment due to several advantages, including the ability to simu...

  20. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2014-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 décembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  1. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 4 décembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  2. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 5 juin de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  3. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC-EPA organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 5 juin de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  4. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 6 mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  5. GAC-EPA

    CERN Document Server

    GAC-EPA

    2013-01-01

    Dear GAC-EPA members, This year, owing to works in the main Auditorium, we have to hold our General assembly in the auditorium of the Globe on 27 March 2013 and we really hope that you can be present. We wish to give you some preliminary practical recommendations: Do not forget your CERN access card, the guards may carry out checks. As far as possible, use public transport because there is very limited parking. If you come by car, park your vehicle on the car parks inside CERN because the outside car park cannot be used by visitors. Refreshments cannot be organized in the Globe; they will be held in cafeteria n°1, which will force us to move by using CERN entrances A or B or via building 33 (access cards required here too). We thank you for your attention and hope to see you soon. Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 avril de 13 h 30 à 16 h 00 Salle de réunion de l&rsquo...

  6. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

        Le GAC organise chaque mois des permanences avec entretiens individuels.     La prochaine permanence se tiendra le : Mardi 6 novembre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel La  permanence suivante aura lieu le mardi 4 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  7. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

        Le GAC organise chaque mois des permanences avec entretiens individuels.     La prochaine permanence se tiendra le : Mardi 5 mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les  permanences suivantes auront lieu les mardis 2 avril, 7 mai, 4 juin, 3 septembre, 1er octobre,  5 novembre  et 3 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  8. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  9. GAC-EPA

    CERN Multimedia

    Staff Association

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 7 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 mai, 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  10. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence, initialement prévue le 7 juin est avancée au mardi 31 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences suivantes auront lieu les mardis 6 septembre, 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  11. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences suivantes auront lieu les mardis 7 juin, 6 septembre, 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  12. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence, initialement prévue le 6 septembre est avancée au mardi 30 août de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences suivantes auront lieu les mardis 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires  

  13. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : mardi 4 octobre de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences suivantes auront lieu les mardis 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  14. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 juin de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  15. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2016-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence, initialement prévue le 6 septembre est avancée au mardi 30 août de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel. Les permanences suivantes auront lieu les mardis 4 octobre, 1er et 29 novembre 2016. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  16. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 6 avril de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 4 mai, 1er juin, 7 septembre, 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  17. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 7 septembre de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  18. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO   Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 2 mars de 13h30 à 16h30 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 6 avril, 4 mai, 1er juin, 7 septembre, 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  19. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 4 mai de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er juin, 7 septembre, 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  20. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 13 avril de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 4 mai, 1er juin, 7 septembre, 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  1. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 3 avril de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. CARTE DE MEMBRE Notre Groupement étant créé, selon nos Statuts, dans le cadre de l'Association du personnel du CERN (AP), chaque membre de notre Groupement est automatiquement membre de l'AP (statut 'membre pensionné'). En conséquence chacun d'entre nous p...

  2. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le :   Mardi 7 septembre de 13h30 à 16h00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   * * * * * Nous avons appris avec tristesse les décès de : M. Bronislaw JUSZCZAK (1947), survenu le 24.06.10. Il avait été mis en pension d’invalidité à 100...

  3. Removal of Pb2+ and Ni2+ by bio-sludge in sequencing batch reactor (SBR) and granular activated carbon-SBR (GAC-SBR) systems.

    Science.gov (United States)

    Sirianuntapiboon, Suntud; Ungkaprasatcha, Ongorn

    2007-10-01

    Living bio-sludge from domestic wastewater treatment plant was used as adsorbent of heavy metals (Pb(2+), Ni(2+)) and its adsorption capacity was about 10-30% reduced by autoclaving at 110 degrees C for 10 min. The living bio-sludge acclimatized in synthetic industrial estate wastewater (SIEWW) without heavy metals showed the highest Pb(2+) and Ni(2+) adsorption capacities at 840+/-20 and 720+/-10 mg/g bio-sludge, respectively. The adsorbed Pb(2+) and Ni(2+) were easily eluted (70-77%) from bio-sludge by washing with 0.1 mol/l HNO(3) solution. The heavy metals (Pb(2+), Ni(2+)) removal efficiency of both SBR and GAC-SBR systems were increased with the increase of hydraulic retention time (HRT), or the decrease of organic loading. The SBR system showed higher heavy metals removal efficiency than GAC-SBR system at the same organic loading or HRT. The Pb(2+), Ni(2+), BOD(5), COD and TKN removal efficiencies of GAC-SBR system were 88.6+/-0.9%, 94.6+/-0.1%, 91.3+/-1.0%, 81.9+/-1.0% and 62.9+/-0.5%, respectively with industrial estate wastewater (IEWW) with 410 mg/l glucose, 5 mg/l Pb(2+) and 5 mg/l Ni(2+) under organic loading of 1.25 kg BOD(5)/m(3) d (HRT of 3 days). The bio-sludge quality (sludge volume index: SVI) of the system was less than 80 ml/g. The excess sludge from both SBR and GAC-SBR systems with SIEWW under the organic loading of 1.25-2.50 kg BOD(5)/m(3) d contained Pb(2+) and Ni(2+) at concentrations of 240-250 mg Pb(2+)/g bio-sludge and 180-210 mg Ni(2+)/g bio-sludge, respectively.

  4. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le :   Mardi 7 décembre de 13h30 à 16h00   Salle de réunion de l’Association du personnel Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   * * * * *   Nous avons appris avec tristesse les décès de : M. Frank BLYTHE décédé le 22 octobre 2010. Né en 1924. Entré au CERN en 1956, il avait pris sa retraite en 1980 (ex-EP). Il laisse une veuve : Mrs Patricia BLYTHE. M. ...

  5. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2013-01-01

    En tant que Président du GAC-EPA, je porte à votre connaissance ce communiqué émanant de la Direction du CERN. Le 2 juin 2013, le CERN inaugure le projet Passeport Big Bang, un parcours touristique et scientifique formé de dix plates-formes d'exposition devant dix sites du CERN dans le Pays de Gex et le Canton de Genève. Les plateformes sont reliées par des itinéraires balisés et par un jeu de piste. C'est un projet est mené en collaboration avec les communes du Pays de Gex, Meyrin et Genève Tourisme dans un souci de renforcer notre dialogue avec nos voisins : http://passeport-big-bang.web.cern.ch/fr. A l’occasion de cette inauguration, nous organisons un événement populaire et festif : le matin, les familles pourront participer à des randonnées à vélo tandis que les sportifs pourront tester les 5...

  6. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2018-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juillet et décembre. La prochaine permanence se tiendra le : Mardi 27 mars de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 24 avril, 29 mai, 26 juin, 28 août, 25 septembre, 30 octobre et 27 novembre 2018. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l&am...

  7. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2018-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juillet et décembre. La prochaine permanence se tiendra le : Mardi 27 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 27 mars, 24 avril, 29 mai, 26 juin, 28 août, 25 septembre, 30 octobre et 27 novembre 2018. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, au...

  8. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2018-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juin, juillet et décembre. La prochaine permanence se tiendra le : Mardi 30 janvier de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 27 février, 27 mars, 24 avril, 29 mai, 26 juin, 28 août, 25 septembre, 30 octobre et 27 novembre 2018. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Nous invitons vivement ces derniers à s’associer à notre groupement en...

  9. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 7 septembre de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   Nous avons appris avec tristesse les décès de : M. Helmut Rottstock (1928), décédé le 14 juillet 2010. Il avait pris sa ret...

  10. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    INFORMATION Le service des maladies osseuses des Hôpitaux Universitaires de Genève (HUG) vous propose de participer à une étude visant à identifier les facteurs de risque de l'ostéoporose. Il est toujours encore à la recherche de personnes intéressées. Si vous êtes une femme entre 63 et 67 ans, un homme entre 63 et 67 ans, vous pouvez contacter Madame le Docteur Claire Durosier au 022 372 71 83 (lundi au vendredi, 9h - 18h). Dr. Jean-Paul DISS   *****   GROUPEMENT DES ANCIENS DU CERN ET DE L’ESO Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le Mardi 4 mai de 13h30 à 16h00 Salle de conférence de l’Association du personnel Les permanences suivantes auront lieu les mardis 1er juin, 7 septembre, 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement...

  11. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 8 février de 13h30 à 16h00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 8 mars, 5 avril, 4 mai, 7 juin, 6 septembre, 4 octobre, 8 novembre, 6 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   * * * * * Nous avons appris avec tristesse les décès de : M. Ferdinand SCHENK (1923), décédé le 26 novembre 2010. Il avait pris sa retraite e...

  12. GAC-EPA

    CERN Document Server

    GAC-EPA

    2011-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 8 février de 13h30 à 16h00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 8 mars, 5 avril, 4 mai, 7 juin, 6 septembre, 4 octobre, 8 novembre, 6 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.   * * * * * Nous avons appris avec tristesse les décès de : Mme Lyda GAECHTER (1927) survenu le 27 novembre 2010. Elle avait été mise en pension d&rsq...

  13. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 7 septembre de 13h30 à 16h00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 5 octobre, 2 novembre et 7 décembre. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. * * * * * Nous avons appris avec tristesse le décès de : M. Ugo Ubaldi (1927), décédé le 9 août 2010. Il avait été mis en pension d'invalidité &agrav...

  14. GAC-EPA

    CERN Multimedia

    GAC-EPA

    2010-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 2 novembre de 13h30 à 16h00 Salle de réunion de l’Association du personnel La permanence suivante aura lieu le mardi 7 décembre.   Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants !) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. * * * * * Nous avons appris avec tristesse les décès de : M. Charles E. HILL, décédé le 4 octobre 2010. Né en 1942. Entré au CERN en 1969, il avait pris sa retraite en 2007 (ex-AB). Il laisse une veuve : Mrs...

  15. Carbon-enhanced VRLA batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Enos, David George; Hund, Thomas D.; Shane, Rod (East Penn Manufacturing, Lyon Station, PA)

    2010-10-01

    The addition of certain forms of carbon to the negative plate in valve regulated lead acid (VRLA) batteries has been demonstrated to increase the cycle life of such batteries by an order of magnitude or more under high-rate, partial-state-of-charge operation. Such performance will provide a significant impact, and in some cases it will be an enabling feature for applications including hybrid electric vehicles, utility ancillary regulation services, wind farm energy smoothing, and solar photovoltaic energy smoothing. There is a critical need to understnd how the carbon interacts with the negative plate and achieves the aforementioned benefits at a fundamental level. Such an understanding will not only enable the performance of such batteries to be optimzied, but also to explore the feasibility of applying this technology to other battery chemistries. In partnership with the East Penn Manufacturing, Sandia will investigate the electrochemical function of the carbon and possibly identify improvements to its anti-sulfation properties. Shiomi, et al. (1997) discovered that the addition of carbon to the negative active material (NAM) substantially reduced PbSO{sub 4} accumulation in high rate, partial state of charge (HRPSoC) cycling applications. This improved performance with a minimal cost. Cycling applications that were uneconomical for traditional VRLA batteries are viable for the carbon enhanced VRLA. The overall goal of this work is to quantitatively define the role that carbon plays in the electrochemistry of a VRLA battery.

  16. GAC adsorption filters as barriers for viruses, bacteria and protozoan (oo)cysts in water treatment.

    Science.gov (United States)

    Hijnen, W A M; Suylen, G M H; Bahlman, J A; Brouwer-Hanzens, A; Medema, G J

    2010-02-01

    Granular Activated Carbon (GAC) adsorption filtration is commonly used in drinking water treatment to remove NOM and micro-pollutants and on base of the process conditions a certain capacity to eliminate pathogenic micro-organisms was expected. The experiences with the mandatory quantitative microbial risk assessment of Dutch drinking water revealed a lack of knowledge on the elimination capacity of this process for pathogens. The objective of the current study was to determine the capacity of GAC filtration to remove MS2, Escherichia coli and spores of Clostridium bifermentans as process indicators for pathogens and more directly of (oo)cysts of Cryptosporidium parvum and Giardia lamblia. Challenge tests with fresh and loaded GAC were performed in pilot plant GAC filters supplied with pre-treated surface water at a contact time which was half of the contact time of the full-scale GAC filters. MS2 phages were not removed and the removal of E. coli and the anaerobic spores was limited ranging from bacteria and (oo)cysts was largely attributed to attachment. The model of the Colloid Filtration Theory was used to describe the removal of the dosed biocolloids in the GAC filters, but the results demonstrated that there is a lack of quantitative knowledge about the influence of collector characteristics on the two major CFT parameters, the single collector and the sticking efficiency. Copyright 2009 Elsevier Ltd. All rights reserved.

  17. Use of chlorination, ozonization and GAC adsorption to eliminate triazine pesticides in water supplies; Eliminacion de plaguicidas en aguas de abastecimiento mediante cloracion, ozonizacion y adsorcion con GAC

    Energy Technology Data Exchange (ETDEWEB)

    Ormad Melero, M. P.; Garcia Castillo, F. J.; Munarriz Cid, B.

    2009-07-01

    This study is focused on the research made between Facsa and Universidad de Zaragoza (Spain) related to the oxidation techniques application by chlorination and ozonization, and their combination with granular activated carbon (GAC) adsorption of mineral origin, in order to control triazine pesticides in water supplies. Experiments are carried out is a pilot plant. Although the chlorination or ozonization can partially degrade pesticides under study (atrazine, simazine, terbutilazine and bromacil), their passing through an adsorption column with GAC mineral, achieves their total removal when their initial concentrations are about 500 ng/l. These concentrations are obtained by fortification of studied sample. (Author) 9 refs.

  18. Magnetic correlations in the magnetocaloric materials Mn3GaC and Mn3GaC0.85N0.15 studied by neutron polarization analysis and neutron depolarization

    Science.gov (United States)

    Çakr, Ö.; Acet, M.; Farle, M.; Wildes, A.

    2016-04-01

    Partially substituting carbon by nitrogen in the antiperovskite compound Mn3GaC increases the first order antiferromagnetic/ferromagnetic transition temperature and at the same time causes the high-temperature long-range ferromagnetism to weaken. To show that the weakening is related to the diminishing of ferromagnetic domain formation, we undertake neutron depolarization and neutron polarization analysis experiments on Mn3GaC and Mn3GaC0.85N0.15. Polarization analysis experiments show that strong ferromagnetic correlations are present at high temperatures in the paramagnetic states of both Mn3GaC and Mn3GaC0.85N0.15 and that these correlations vanish in the antiferromagnetic state. Neutron depolarization studies show that above the first order transition temperature, ferromagnetic domain formation is present in Mn3GaC but is absent in Mn3GaC0.85N0.15. The relationship between ferromagnetic domain formation and transitional hysteresis is brought forward for these two important magnetocaloric materials.

  19. Arsenic adsorption and speciation in drinking water by GAC-based iron-containing adsorbents

    Science.gov (United States)

    Gim, Yewon; Terry, Jeff; Gu, Zhimang; Hua, B.; Deng, Baolin

    2008-04-01

    Granular Activated Carbon (GAC) with Iron adsorbents were developed for effective removal of arsenic from drinking water. The structure and proposed mechanism for As removal was studied using X-ray absorption spectroscopy. The oxidation state of As(III)GAC sample was calculated using XANES spectra and verified to be predominantly As(V). The structure was determined using EXAFS spectra of As(V) and Fe. The Fe spectra suggested thin layer of Fe oxide formation on GAC surface. As data showed As oxide formed bond on the Fe oxide surface. The spectra were calculated using multiple geometrically optimized models calculated using density functional theory. Further calculations were done to verify the structure, and further examine the structure.

  20. Effects of granular activated carbon on methane removal performance and methanotrophic community of a lab-scale bioreactor.

    Science.gov (United States)

    Lee, Eun-Hee; Choi, Sun-Ah; Yi, Taewoo; Kim, Tae Gwan; Lee, Sang-Don; Cho, Kyung-Suk

    2015-01-01

    Two identical lab-scale bioreactor systems were operated to examine the effects of granular activated carbon (GAC) on methane removal performance and methanotrophic community. Both bioreactor systems removed methane completely at a CH4 loading rate of 71.2 g-CH4·d(-1) for 17 days. However, the methane removal efficiency declined to 88% in the bioreactor without GAC, while the bioreactor amended with GAC showed greater methane removal efficiency of 97% at a CH4 loading rate of 107.5 g-CH4·d(-1). Although quantitative real-time PCR showed that methanotrophic populations were similar levels of 5-10 × 10(8) pmoA gene copy number·VSS(-1) in both systems, GAC addition changed the methanotrophic community composition of the bioreactor systems. Microarray assay revealed that GAC enhanced the type I methanotrophic genera including Methylobacter, Methylomicrobium, and Methylomonas of the system, which suggests that GAC probably provided a favorable environment for type I methanotrophs. These results indicated that GAC is a promising support material in bioreactor systems for CH4 mitigation.

  1. A microbial fluidized electrode electrolysis cell (MFEEC) for enhanced hydrogen production

    KAUST Repository

    Liu, Jia

    2014-12-01

    A microbial fluidized electrode electrolysis cell (MFEEC) was used to enhance hydrogen gas production from dissolved organic matter. Flowable granular activated carbon (GAC) particles were used to provide additional surface area for growth of exoelectrogenic bacteria. The use of this exoelectrogenic biofilm on the GAC particles with fluidization produced higher current densities and hydrogen gas recoveries than controls (no recirculation or no GAC), due to intermittent contact of the capacitive particles with the anode. The total cumulative charge of 1688C m-2 with the MFEEC reactor (a recirculation flow rate of 19 mL min-1) was 20% higher than that of the control reactor (no GAC). The highest hydrogen gas yield of 0.82 ± 0.01 mol-H2/mol-acetate (17 mL min-1) was 39% higher than that obtained without recirculation (0.59 ± 0.01 mol-H 2/mol-acetate), and 116% higher than that of the control (no GAC, without recirculation). These results show that flowable GAC particles provide a useful approach for enhancing hydrogen gas production in bioelectrochemical systems. © 2014 Elsevier B.V. All rights reserved.

  2. A gacS deletion in Pseudomonas aeruginosa cystic fibrosis isolate CHA shapes its virulence.

    Directory of Open Access Journals (Sweden)

    Khady Mayebine Sall

    Full Text Available Pseudomonas aeruginosa, a human opportunistic pathogen, is capable of provoking acute and chronic infections that are associated with defined sets of virulence factors. During chronic infections, the bacterium accumulates mutations that silence some and activate other genes. Here we show that the cystic fibrosis isolate CHA exhibits a unique virulence phenotype featuring a mucoid morphology, an active Type III Secretion System (T3SS, hallmark of acute infections, and no Type VI Secretion System (H1-T6SS. This virulence profile is due to a 426 bp deletion in the 3' end of the gacS gene encoding an essential regulatory protein. The absence of GacS disturbs the Gac/Rsm pathway leading to depletion of the small regulatory RNAs RsmY/RsmZ and, in consequence, to expression of T3SS, while switching off the expression of H1-T6SS and Pel polysaccharides. The CHA isolate also exhibits full ability to swim and twitch, due to active flagellum and Type IVa pili. Thus, unlike the classical scheme of balance between virulence factors, clinical strains may adapt to a local niche by expressing both alginate exopolysaccharide, a hallmark of membrane stress that protects from antibiotic action, host defences and phagocytosis, and efficient T3S machinery that is considered as an aggressive virulence factor.

  3. Enhanced Carbon Nanotube Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  4. Carbon Nanotube-Enhanced Carbon-Phenenolic Ablator Material

    Science.gov (United States)

    Kikolaev, P.; Stackpoole, M.; Fan, W.; Cruden, B. A.; Waid, M.; Moloney, P.; Arepalli, S.; Arnold, J.; Partridge, H.; Yowell, L.

    2006-01-01

    This viewgraph presentation reviews the use of PICA (phenolic impregnated carbon ablator) as the selected material for heat shielding for future earth return vehicles. It briefly reviews the manufacturing of PICA and the advantages for the use of heat shielding, and then explains the reason for using Carbon Nanotubes to improve strength of phenolic resin that binds carbon fibers together. It reviews the work being done to create a carbon nanotube enhanced PICA. Also shown are various micrographic images of the various PICA materials.

  5. Performance Enhancement of Carbon Nanomaterials for Supercapacitors

    Directory of Open Access Journals (Sweden)

    Amin M. Saleem

    2016-01-01

    Full Text Available Carbon nanomaterials such as carbon nanotubes, carbon nanofibers, and graphene are exploited extensively due to their unique electrical, mechanical, and thermal properties and recently investigated for energy storage application (supercapacitor due to additional high specific surface area and chemical inertness properties. The supercapacitor is an energy storage device which, in addition to long cycle life (one million, can give energy density higher than parallel plate capacitor and power density higher than battery. In this paper, carbon nanomaterials and their composites are reviewed for prospective use as electrodes for supercapacitor. Moreover, different physical and chemical treatments on these nanomaterials which can potentially enhance the capacitance are also reviewed.

  6. Bright luminescence of Vibrio fischeri aconitase mutants reveals a connection between citrate and the Gac/Csr regulatory system.

    Science.gov (United States)

    Septer, Alecia N; Bose, Jeffrey L; Lipzen, Anna; Martin, Joel; Whistler, Cheryl; Stabb, Eric V

    2015-01-01

    The Gac/Csr regulatory system is conserved throughout the γ-proteobacteria and controls key pathways in central carbon metabolism, quorum sensing, biofilm formation and virulence in important plant and animal pathogens. Here we show that elevated intracellular citrate levels in a Vibrio fischeri aconitase mutant correlate with activation of the Gac/Csr cascade and induction of bright luminescence. Spontaneous or directed mutations in the gene that encodes citrate synthase reversed the bright luminescence of aconitase mutants, eliminated their citrate accumulation and reversed their elevated expression of CsrB. Our data elucidate a correlative link between central metabolic and regulatory pathways, and they suggest that the Gac system senses a blockage at the aconitase step of the tricarboxylic acid cycle, either through elevated citrate levels or a secondary metabolic effect of citrate accumulation, and responds by modulating carbon flow and various functions associated with host colonization, including bioluminescence. © 2014 John Wiley & Sons Ltd.

  7. Computational investigation of the flow field contribution to improve electricity generation in granular activated carbon-assisted microbial fuel cells

    Science.gov (United States)

    Zhao, Lei; Li, Jian; Battaglia, Francine; He, Zhen

    2016-11-01

    Microbial fuel cells (MFCs) offer an alternative approach to treat wastewater with less energy input and direct electricity generation. To optimize MFC anodic performance, adding granular activated carbon (GAC) has been proved to be an effective way, most likely due to the enlarged electrode surface for biomass attachment and improved mixing of the flow field. The impact of a flow field on the current enhancement within a porous anode medium (e.g., GAC) has not been well understood before, and thus is investigated in this study by using mathematical modeling of the multi-order Butler-Volmer equation with computational fluid dynamics (CFD) techniques. By comparing three different CFD cases (without GAC, with GAC as a nonreactive porous medium, and with GAC as a reactive porous medium), it is demonstrated that adding GAC contributes to a uniform flow field and a total current enhancement of 17%, a factor that cannot be neglected in MFC design. However, in an actual MFC operation, this percentage could be even higher because of the microbial competition and energy loss issues within a porous medium. The results of the present study are expected to help with formulating strategies to optimize MFC with a better flow pattern design.

  8. Microtiter plate based colorimetric assay for characterization of dehalogenation activity of GAC/Fe0 composite

    OpenAIRE

    Hwang, Yuhoon; Salatas, Apostolos; Mines, Paul D.; Jakobsen, Mogens Havsteen; Andersen, Henrik Rasmus

    2015-01-01

    Even though nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, a quantification of nZVIreactivity has not been standardized. Here, we developed series of colorimetric assays for determining reductive activity of nZVI and its composite with granular activated carbon(GAC). The assay focused on analysis of reaction products rather than its mother compounds, which gives more accurate quantification of reductive ...

  9. Feasibility of treating emulsified oily and salty wastewaters through coagulation and bio-regenerated GAC filtration.

    Science.gov (United States)

    Mancini, Giuseppe; Panzica, Michele; Fino, Debora; Cappello, Simone; Yakimov, Michail M; Luciano, Antonella

    2017-12-01

    In the present study, chemical oxygen demand (COD) removal by coagulation and packed-columns of both fresh and bioregenerated granular activated carbon (GAC) is reported as a feasible treatment for saline and oily wastewaters (slops) generated from marine oil tankers cleaning. The use of Ferric chloride (FeCl3), Aluminium sulphate (Al2(SO4)3) and Polyaluminum chloride (Al2(OH3)Cl3) was evaluated in the pre-treatment by coagulation of a real slop, after a de-oiling phase in a tank skimmer Comparison of coagulation process indicated that Polyaluminum chloride and Aluminium sulphate operate equally well (20-30% of COD removal) when applied at their optimal dose (40 and 90 mg/l respectively) but the latter should be preferred in order to significantly control the sludge production. The results from the column filtration tests indicated the feasibility of using the selected GAC (Filtrasorb 400 -Calgon Carbon Corporation) to achieve the respect of the discharge limits in the slops treatment with a carbon usage rate in the range 0.1-0.3 kg/m3 of treated effluent. Moreover, biological regeneration through Alcalinovorax borkumensis SK2 was proved to be a cost-effective procedure since the reuse of spent GAC through such regeneration process for further treatment could still achieve approximately 90% of the initial sorption capacity, reducing then costs for the use of new sorbents and also the need for waste disposal. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Ammonium removal of drinking water at low temperature by activated carbon filter biologically enhanced with heterotrophic nitrifying bacteria.

    Science.gov (United States)

    Qin, Wen; Li, Wei-Guang; Zhang, Duo-Ying; Huang, Xiao-Fei; Song, Yang

    2016-03-01

    We sought to confirm whether use of Acinetobacter strains Y7 and Y16, both strains of heterotrophic nitrifying bacteria, was practical for removing ammonium (NH4 (+)-N) from drinking water at low temperatures. To test this, ammonium-containing drinking water was treated with strains Y7 and Y16 at 8 and 2 °C. Continuous ammonium treatment was conducted in order to evaluate the performance of three biologically enhanced activated carbon (BEAC) filters in removing ammonium. The three BEAC filters were inoculated with strain Y7, strain Y16, and a mixture of strains Y7 and Y16, respectively. A granular activated carbon (GAC) filter, without inoculation by any strains, was tested in parallel with the BEAC filters as control. The results indicated that NH4 (+)-N removal was significant when a BEAC filter was inoculated with the mixture of strains Y7 and Y16 (BEAC-III filter). Amounts of 0.44 ± 0.05 and 0.25 ± 0.05 mg L(-1) NH4 (+)-N were removed using the BEAC-III filter at 8 and 2 °C, respectively. These values were 2.8-4.0-fold higher than the values of ammonium removal acquired using the GAC filter. The synergistic effect of using strains Y7 and Y16 in concert was the cause of the high-ammonium removal efficiency achieved by using the BEAC-III filter at low temperatures. In addition, a high C/N ratio may promote NH4 (+)-N removal efficiency by improving biomass and microbial activity. This study provides new insight into the use of biofilters to achieve biological removal of ammonium at low temperature.

  11. Proteomic Analysis of a Global Regulator GacS Sensor Kinase in the Rhizobacterium, Pseudomonas chlororaphis O6

    Directory of Open Access Journals (Sweden)

    Chul Hong Kim

    2014-06-01

    Full Text Available The GacS/GacA system in the root colonizer Pseudomonas chlororaphis O6 is a key regulator of many traits relevant to the biocontrol function of this bacterium. Proteomic analysis revealed 12 proteins were down-regulated in a gacS mutant of P. chlororaphis O6. These GacS-regulated proteins functioned in combating oxidative stress, cell signaling, biosynthesis of secondary metabolism, and secretion. The extent of regulation was shown by real-time RT-PCR to vary between the genes. Mutants of P. chlororaphis O6 were generated in two GacS-regulated genes, trpE, encoding a protein involved in tryptophan synthesis, and prnA, required for conversion of tryptophan to the antimicrobial compound, pyrrolitrin. Failure of the trpE mutant to induce systemic resistance in tobacco against a foliar pathogen causing soft rot, Pectobacterium carotovorum SCCI, correlated with reduced colonization of root surfaces implying an inadequate supply of tryptophan to support growth. Although colonization was not affected by mutation in the prnA gene, induction of systemic resistance was reduced, suggesting that pyrrolnitrin was an activator of plant resistance as well as an antifungal agent. Study of mutants in the other GacS-regulated proteins will indicate further the features required for biocontrol-activity in this rhizobacterium.

  12. Removal of Chloroform (CHCl3 from Tehran Drinking Water by GAC and Air Stripping Columns

    Directory of Open Access Journals (Sweden)

    M T Samadi, S Nasseri, A Mesdaghinia, M R Alizadefard

    2004-07-01

    Full Text Available The harmful substances, defined as trihalomethanes (THMs, were found to be formed during the disinfection of drinking water when chlorine was used as the disinfectant. In this research, the effectiveness of granular activated carbon (GAC and air stripping (AS packed column for the removal of chloroform (CHCl3 (as THMs basic indicator compound in many resources in range of 50 to300µg/L, from drinking water was studied. Pilots of GAC and air stripping columns were designed and set up. The study was carried out for the two cases of deionized and chlorinated Tehran tap water. Also the effects of flow rate, chloroform and TDS concentrations were considered in both treatment systems. Gas chromatography (GC with electron capture detector (ECD was used for determination of chloroform concentration in inlet and outlet samples. The obtained data were analyzed by SPSS and non-parametric Kruskal–Wallis method. Results showed a positive correlation between the flow rate and chloroform concentration, and removal efficiencies. The average of variations of removal efficiencies for AS and GAC columns with deionized water samples were, 89.9%, 71.2% and for chlorinated Tehran tap water were 91.2% and 76.4%, respectively. The removal of feed residual chlorine in these columns with 0.5, 0.8 ppm was 100%, respectively and re-chlorination for finishing water was recommended. Results showed AS to be considered more effective in chloroform removal for conventional water treatment plants as a finishing process.

  13. Titania carbon nanotube composites for enhanced photocatalysis

    Science.gov (United States)

    Pyrgiotakis, Georgios

    Photocatalytic composites have been used for the past few decades in a wide range of applications. The most common application is the purification of air and water by removing toxic compounds. There is limited use however towards biocidal applications. Despite their high efficiency, photocatalytic materials are not comparable to the effectiveness of conventional biocidal compounds such as chlorine and alcoholic disinfectants. On the other hand, nearly a decade ago with the discovery of the carbon nanotubes a new vibrant scientific field emerged. Nanotubes are unique structures of carbon that posse amazing electrical, mechanical and thermal properties. In this research carbon nanotubes are used as photocatalytic enhancers. They were coated with anatase titania to form a composite material. Two different types of nanotubes (metallic versus non-metallic) were used and the photocatalytic activity was measured. The metallic tubes demonstrated exceptional photocatalytic properties, while non-metallic tubes had low photocatalytic efficiency. The reason for that difference was investigated and was the major focus of this research. The research concluded that the reasons for the high efficiency of the carbon nanotubes were (i) the metallic nature of the tubes and (ii) the possible bond between the titania coating and the underlying graphite layers (C-O-Ti). Since both composites had the same indications regarding the C-O-Ti bond, the metallic nature of the carbon nanotubes is believed to be the most dominant factor contributing to the enhancement of the photocatalysis. The composite material may have other potential applications such as for sensing and photovoltaic uses.

  14. Catalytic Sorption of (Chloro)Benzene and Napthalene in Aqueous Solutions by Granular Activated Carbon Supported Bimetallic Iron and Palladium Nanoparticles

    Science.gov (United States)

    Adsorption of benzene, chlorobenzene, and naphthalene on commercially available granular activated carbon (GAC) and bimetallic nanoparticle (Fe/Pd) loaded GAC was investigated for the potential use in active capping of contaminated sediments. Freundlich and Langmuir linearizatio...

  15. Passivation process and the mechanism of packing particles in the Fe0/GAC system during the treatment of ABS resin wastewater.

    Science.gov (United States)

    Lai, Bo; Zhou, Yuexi; Wang, Juling; Zhang, Yunhong; Chen, Zhiqiang

    2014-01-01

    This study provides mechanistic insights into the passivation of the packing particles during the treatment of acrylonitrile-butadiene-styrene (ABS) resin wastewater by the Fe0/GAC system. The granular-activated carbon (GAC) and iron chippings (Fe0) were mixed together with a volumetric ratio of 1:1. GAC has a mean particle size of approximately 3-5 mm, a specific surface of 748 m2 g(-1), a total pore volume of 0.48 mL g(-1) and a bulk density of 0.49 g cm(-3). The iron chippings have a compact and non-porous surface morphology. The results show that the packing particles in the Fe0/GAC system would lose their activity because the removal of TOC and PO4(3-) for ABS resin wastewater could not carried out by the Fe0/GAC system after 40 days continuous running. Meanwhile, the availability of O2 and intrinsic reactivity of Fe0 play a key role on the form of passive film with different iron oxidation states. The passive film on the surface of iron chippings was formed by two phases: (a) local corrosion phase (0-20 d) and (b) co-precipitation phase (20-40 d), while that of GAC was mainly formed by the co-precipitation of corrosion products with SO4(2-) and PO4(3-) because SO4(2-) and PO4(3-) would not easily reach the Fe0 surface. Therefore, in order to avoid the occurrence of filler passivation, high concentrations of SO4(2-) and PO4(3-) in wastewater should be removed before the treatment process of the Fe/GAC system.

  16. PtrA Is Functionally Intertwined with GacS in Regulating the Biocontrol Activity of Pseudomonas chlororaphis PA23

    Science.gov (United States)

    Shah, Nidhi; Klaponski, Natasha; Selin, Carrie; Rudney, Rachel; Fernando, W. G. Dilantha; Belmonte, Mark F.; de Kievit, Teresa R.

    2016-01-01

    In vitro inhibition of the fungal pathogen Sclerotinia sclerotiorum by Pseudomonas chlororaphis PA23 is reliant upon a LysR-type transcriptional regulator (LTTR) called PtrA. In the current study, we show that Sclerotinia stem rot and leaf infection are significantly increased in canola plants inoculated with the ptrA-mutant compared to the wild type, establishing PtrA as an essential regulator of PA23 biocontrol. LTTRs typically regulate targets that are upstream of and divergently transcribed from the LTTR locus. We identified a short chain dehydrogenase (scd) gene immediately upstream of ptrA. Characterization of a scd mutant revealed that it is phenotypically identical to the wild type. Moreover, scd transcript abundance was unchanged in the ptrA mutant. These findings indicate that PtrA regulation does not involve scd, rather this LTTR controls genes located elsewhere on the chromosome. Employing a combination of complementation and transcriptional analysis we investigated whether connections exist between PtrA and other regulators of biocontrol. Besides ptrA, gacS was the only gene able to partially rescue the wild-type phenotype, establishing a connection between PtrA and the sensor kinase GacS. Transcriptomic analysis revealed decreased expression of biosynthetic (phzA, prnA) and regulatory genes (phzI, phzR, rpoS, gacA, rsmX, rsmZ, retS) in the ptrA mutant; conversely, rsmE, and rsmY were markedly upregulated. The transcript abundance of ptrA was nine-fold higher in the mutant background indicating that this LTTR negatively autoregulates itself. In summary, PtrA is an essential regulator of genes required for PA23 biocontrol that is functionally intertwined with GacS. PMID:27713742

  17. The evaluation of empty bed contact time on the biodegradation of pentachlorophenol using an anaerobic GAC fluidized bed

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, G.J.; Khodadoust, A.P.; Suidan, M.T. [Univ. of Cincinnati, OH (United States); Wagner, J.A. [CH2M Hill, Milwaukee, WI (United States); Brenner, R.C. [Environmental Protection Agency, Cincinnati, OH (United States)

    1994-12-31

    The objective of this research is to evaluate the effects of decreasing the empty-bed contact time (EBCT) on pentachlorophenol and its intermediates utilizing an anaerobic granular activated carbon (GAC) fluidized bed. The bioreactor A was fed an 100 mg/l influent concentration of PCP. EBCTs of 1.167 to 0.292 days for reactor A resulted in a PCP reduction greater than 99%. In addition, an equimolar conversion of PCP to monochlorophenol was observed.

  18. Conservation of the response regulator gene gacA in Pseudomonas species

    NARCIS (Netherlands)

    Souza, J.T.; Mazzola, M.; Raaijmakers, J.M.

    2003-01-01

    The response regulator gene gacA influences the production of several secondary metabolites in both pathogenic and beneficial Pseudomonas spp. In this study, we developed primers and a probe for the gacA gene of Pseudomonas species and sequenced a 425 bp fragment of gacA from ten Pseudomonas strains

  19. Rerouting Carbon Flux To Enhance Photosynthetic Productivity

    Energy Technology Data Exchange (ETDEWEB)

    Ducat, DC; Avelar-Rivas, JA; Way, JC; Silver, PA

    2012-03-23

    The bioindustrial production of fuels, chemicals, and therapeutics typically relies upon carbohydrate inputs derived from agricultural plants, resulting in the entanglement of food and chemical commodity markets. We demonstrate the efficient production of sucrose from a cyanobacterial species, Synechococcus elongatus, heterologously expressing a symporter of protons and sucrose (cscB). cscB-expressing cyanobacteria export sucrose irreversibly to concentrations of >10 mM without culture toxicity. Moreover, sucrose-exporting cyanobacteria exhibit increased biomass production rates relative to wild-type strains, accompanied by enhanced photosystem II activity, carbon fixation, and chlorophyll content. The genetic modification of sucrose biosynthesis pathways to minimize competing glucose-or sucrose-consuming reactions can further improve sucrose production, allowing the export of sucrose at rates of up to 36.1 mg liter(-1) h illumination(-1). This rate of production exceeds that of previous reports of targeted, photobiological production from microbes. Engineered S. elongatus produces sucrose in sufficient quantities (up to similar to 80% of total biomass) such that it may be a viable alternative to sugar synthesis from terrestrial plants, including sugarcane.

  20. Growth enhancement by soil derived carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Grodzinski, B.; Wallis, M.; O' Sullivan, J. (Univ. of Guelph, Ontario (Canada))

    1989-04-01

    The objective of this study was to investigate the role which naturally evolved CO{sub 2} from the soil can play in the early growth and establishment of vegetable transplants in the field. Two planting dates were utilized to examine the effects of the time of tunnel placement on development of a crop of bell peppers, Capsicum annuum L. Ambient CO{sub 2} levels were 340 {plus minus} 4 ppm. In the first 3 weeks of spring (May) CO levels 2 to 3 cm above the soil surface were 420 to 480 ppm. Inside plastic tunnels the upward flux of CO{sub 2} evolved from the soil was restricted effectively raising the tunnel atmosphere to over 3000 ppm even at midday. Data from parallel field and controlled environment chamber experiments support the view that 25-40% of the increase in seedling growth in the field tunnels in the spring was due to enhanced photosynthesis and carbon partitioning into both sugars and starch not merely the elevated temperatures associated with protected structures.

  1. Synthesis of iron/GAC catalyst for wastewater treatment using ...

    Indian Academy of Sciences (India)

    38, No. 4, August 2015, pp. 1039–1042. c Indian Academy of Sciences. Synthesis of iron/GAC catalyst for wastewater treatment using heterogeneous Fenton reaction. STTLE1,2, T T NGO3, W KHANITCHAIDECHA1,2 and A NAKARUK4,5,∗. 1Department of Civil Engineering, Faculty of Engineering, Naresuan University, ...

  2. Spontaneous phenotypic suppression of GacA-defective Vibrio fischeri is achieved via mutation of csrA and ihfA.

    Science.gov (United States)

    Foxall, Randi L; Ballok, Alicia E; Avitabile, Ashley; Whistler, Cheryl A

    2015-09-16

    Symbiosis defective GacA-mutant derivatives of Vibrio fischeri are growth impaired thereby creating a selective advantage for growth-enhanced spontaneous suppressors. Suppressors were isolated and characterized for effects of the mutations on gacA-mutant defects of growth, siderophore activity and luminescence. The mutations were identified by targeted and whole genome sequencing. Most mutations that restored multiple phenotypes were non-null mutations that mapped to conserved domains in or altered expression of CsrA, a post-transcriptional regulator that mediates GacA effects in a number of bacterial species. These represent an array of unique mutations compared to those that have been described previously. Different substitutions at the same amino acid residue were identified allowing comparisons of effects such as at the R6 residue, which conferred relative differences in luminescence and siderophore levels. The screen revealed residues not previously identified as critical for function including a single native alanine. Most csrA mutations enhanced luminescence more than siderophore activity, which was especially evident for mutations predicted to reduce the amount of CsrA. Although CsrA mutations compensate for many known GacA mutant defects, not all CsrA suppressors restore symbiotic colonization. Phenotypes of a suppressor allele of ihfA that encodes one subunit of the integration host factor (IHF) heteroduplex indicated the protein represses siderophore and activates luminescence in a GacA-independent manner. In addition to its established role in regulation of central metabolism, the CsrA regulator represses luminescence and siderophore as an intermediate of the GacA regulatory hierachy. Siderophore regulation was less sensitive to stoichiometry of CsrA consistent with higher affinity for the targets of this trait. The lack of CsrA null-mutant recovery implied these mutations do not enhance fitness of gacA mutants and alluded to this gene being

  3. Studies on Enhancing Transverse Thermal Conductivity Carbon/Carbon Composites

    National Research Council Canada - National Science Library

    Manocha, Lalit M; Manocha, Satish M; Roy, Ajit

    2007-01-01

    The structure derived potential properties of Graphite such as high stiffness coupled with high thermal conductivity and low coefficient of thermal expansion have been better achieved in Carbon fibers...

  4. Using organoclays to enhance carbon filtration.

    Science.gov (United States)

    Alther, George

    2002-01-01

    Organoclays have found increased acceptance as pre-treatment for activated carbon adsorption systems in both groundwater and wastewater cleanup. The reason is that activated carbon tends to become quickly blinded by large organic molecules of low solubility, particularly oils. However, it is also well established that activated carbon is more efficient at low concentrations of organic contaminants than at higher ones, i.e. at less than 1 ppm. With organoclays it is exactly the opposite, they are better at removing organics at higher concentrations, above 3 ppm. Therefore it is cost effective in these applications to use two or more vessels in series, the first one filled with organoclay, the remainder with activated carbon. The economics make sense, even though the organoclay is not regenerated, because of the reduction in down time every time a carbon vessel has to be changed out. Use of organoclays increases the volume treated by carbon in many applications seven to nine fold. In the case of other organic contaminants, as the aqueous solubility increases, the efficiency decreases, except in the case of methylene chloride, which it removes at far higher efficiency then carbon. This article presents the results of a series of tests, including Kd determinations, jar tests, and mini-column tests. These tests determined the adsorption capacity and efficiency of organoclay and activated carbon for the removal of benzene, toluene, xylene and naphtalene from water. These tests were followed by adding the four compounds into one container to see if the combination of organoclay, followed by carbon, would be more efficient then each sorbent alone. The tests also compared the efficiency of organoclay versus carbon for the removal of various oils from water.

  5. Natural Biowaste-Cocoon-Derived Granular Activated Carbon-Coated ZnO Nanorods: A Simple Route To Synthesizing a Core-Shell Structure and Its Highly Enhanced UV and Hydrogen Sensing Properties.

    Science.gov (United States)

    Saravanan, Adhimoorthy; Huang, Bohr-Ran; Kathiravan, Deepa; Prasannan, Adhimoorthy

    2017-11-15

    Granular activated carbon (GAC) materials were prepared via simple gas activation of silkworm cocoons and were coated on ZnO nanorods (ZNRs) by the facile hydrothermal method. The present combination of GAC and ZNRs shows a core-shell structure (where the GAC is coated on the surface of ZNRs) and is exposed by systematic material analysis. The as-prepared samples were then fabricated as dual-functional sensors and, most fascinatingly, the as-fabricated core-shell structure exhibits better UV and H2 sensing properties than those of as-fabricated ZNRs and GAC. Thus, the present core-shell structure-based H2 sensor exhibits fast responses of 11% (10 ppm) and 23.2% (200 ppm) with ultrafast response and recovery. However, the UV sensor offers an ultrahigh photoresponsivity of 57.9 A W-1, which is superior to that of as-grown ZNRs (0.6 A W-1). Besides this, switching photoresponse of GAC/ZNR core-shell structures exhibits a higher switching ratio (between dark and photocurrent) of 1585, with ultrafast response and recovery, than that of as-grown ZNRs (40). Because of the fast adsorption ability of GAC, it was observed that the finest distribution of GAC on ZNRs results in rapid electron transportation between the conduction bands of GAC and ZNRs while sensing H2 and UV. Furthermore, the present core-shell structure-based UV and H2 sensors also well-retained excellent sensitivity, repeatability, and long-term stability. Thus, the salient feature of this combination is that it provides a dual-functional sensor with biowaste cocoon and ZnO, which is ecological and inexpensive.

  6. Carbon-enhanced metal-poor stars and thermohaline mixing

    NARCIS (Netherlands)

    Stancliffe, R.J.; Glebbeek, E.|info:eu-repo/dai/nl/30483324X; Izzard, R.G.|info:eu-repo/dai/nl/304836052; Pols, O.R.|info:eu-repo/dai/nl/111811155

    2007-01-01

    One possible scenario for the formation of carbon-enhanced metal-poor stars is the accretion of carbon-rich material from a binary companion which may no longer visible. It is generally assumed that the accreted material remains on the surface of the star and does not mix with the interior until

  7. Self Assembled Carbon Nanotube Enhanced Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this NASA STTR program is to develop single wall carbon nanotube (SWCNT) based ultracapacitors for energy storage devices (ESD) application, using...

  8. Pretreatment of old-age landfill leachate by microwave-assisted catalytic oxidation in the presence of activated carbon.

    Science.gov (United States)

    Xu, Xiao-Chun; Zhang, Hong-Tao; Dong, Zhi-Yong; Fan, Yu-Feng

    2013-01-01

    Landfill leachate is posing an ever-greater environmental hazard. Recently, a process for purification combining activated carbon, microwave (MW) and Fenton oxidation has drawn much attention. In this study, the effectiveness of this process for the pretreatment of an old-age landfill leachate was tested. The effects of various parameters were investigated and the optimal condition included as follows: MW energy density, 6 W/mL; MW power, 300 W; radiation time, 8 min; H2O2 dosage, 0.1 mol/L; Fe(2+)-EDTA dosage, 0.02 mol/L; granular activated carbon (GAC) dosage, 6 g/L. Within the present experimental condition applied, the chemical oxygen demand (COD) removal reached 56.5%, and the ratio of 5-day biochemical oxygen demand to chemical oxygen demand (BOD5/COD) was enhanced from 0.122 to 0.462. Comparing with GAC, MW and Fenton alone or the combinations of any two of them, MW/Fenton/GAC displayed superior treatment efficiency. The MW/Fenton/GAC process is believed to be a promising pretreatment technology for biorefractory old-age landfill leachate.

  9. Impact of UV-H2O2 Advanced Oxidation and Aging Processes on GAC Capacity for the Removal of Cyanobacterial Taste and Odor Compounds.

    Science.gov (United States)

    Zamyadi, Arash; Sawade, Emma; Ho, Lionel; Newcombe, Gayle; Hofmann, Ron

    2015-01-01

    Cyanobacteria and their taste and odor (T&O) compounds are a growing concern in water sources globally. Geosmin and 2-methylisoborneol (MIB) are the most commonly detected T&O compounds associated with cyanobacterial presence in drinking water sources. The use of ultraviolet and hydrogen peroxide (H2O2) as an advanced oxidation treatment for T&O control is an emerging technology. However, residual H2O2 (>80% of the initial dose) has to be removed from water prior final disinfection. Recently, granular activated carbon (GAC) is used to remove H2O2 residual. The objective of this study is to assess the impact of H2O2 quenching and aging processes on GAC capacity for the removal of geosmin and MIB. Pilot columns with different types of GAC and presence/absence of H2O2 have been used for this study. H2O2 removal for the operational period of 6 months has no significant impact on GAC capacity to remove the geosmin and MIB from water.

  10. Impact of UV–H2O2 Advanced Oxidation and Aging Processes on GAC Capacity for the Removal of Cyanobacterial Taste and Odor Compounds

    Science.gov (United States)

    Zamyadi, Arash; Sawade, Emma; Ho, Lionel; Newcombe, Gayle; Hofmann, Ron

    2015-01-01

    Cyanobacteria and their taste and odor (T&O) compounds are a growing concern in water sources globally. Geosmin and 2-methylisoborneol (MIB) are the most commonly detected T&O compounds associated with cyanobacterial presence in drinking water sources. The use of ultraviolet and hydrogen peroxide (H2O2) as an advanced oxidation treatment for T&O control is an emerging technology. However, residual H2O2 (>80% of the initial dose) has to be removed from water prior final disinfection. Recently, granular activated carbon (GAC) is used to remove H2O2 residual. The objective of this study is to assess the impact of H2O2 quenching and aging processes on GAC capacity for the removal of geosmin and MIB. Pilot columns with different types of GAC and presence/absence of H2O2 have been used for this study. H2O2 removal for the operational period of 6 months has no significant impact on GAC capacity to remove the geosmin and MIB from water. PMID:26462247

  11. Decolorization and chemical regeneration of granular activated carbon used in citric acid refining

    Directory of Open Access Journals (Sweden)

    Kang Sun

    2009-04-01

    Full Text Available Citric acid fermentation (CAF liquor decolorization by granular activated carbon (GAC was studied and an improved chemical regeneration method of the exhausted GAC by the color of CAF liquor was investigated. The effects of the GAC dosage, time and temperature on the decoloring efficiency (DE % were studied. The DE % of the original GAC was 91 %. The regeneration efficiency (RE % using chemical regents was 104 % of the original GAC. Hot water as cheap reagent was found to be much helpful to the regeneration efficiency. Using oxidant and surfactant in addition to just using NaOH solution can recover 10 % more adsorption capacity of renewed GAC. The adding dosage of oxidant is good at 3 % of exhausted GAC weight; that of surfactant is good at 0.1 %. Comparing with steam regeneration method, high regeneration yield (> 95 % of chemical method was an attractive economic factor. The results of this investigation can be as helpful reference for citric acid manufacturer expanding profits.

  12. Biologically Enhanced Carbon Sequestration: Research Needs and Opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, Curtis; Oldenburg, Curtis M.; Torn, Margaret S.

    2008-03-21

    Fossil fuel combustion, deforestation, and biomass burning are the dominant contributors to increasing atmospheric carbon dioxide (CO{sub 2}) concentrations and global warming. Many approaches to mitigating CO{sub 2} emissions are being pursued, and among the most promising are terrestrial and geologic carbon sequestration. Recent advances in ecology and microbial biology offer promising new possibilities for enhancing terrestrial and geologic carbon sequestration. A workshop was held October 29, 2007, at Lawrence Berkeley National Laboratory (LBNL) on Biologically Enhanced Carbon Sequestration (BECS). The workshop participants (approximately 30 scientists from California, Illinois, Oregon, Montana, and New Mexico) developed a prioritized list of research needed to make progress in the development of biological enhancements to improve terrestrial and geologic carbon sequestration. The workshop participants also identified a number of areas of supporting science that are critical to making progress in the fundamental research areas. The purpose of this position paper is to summarize and elaborate upon the findings of the workshop. The paper considers terrestrial and geologic carbon sequestration separately. First, we present a summary in outline form of the research roadmaps for terrestrial and geologic BECS. This outline is elaborated upon in the narrative sections that follow. The narrative sections start with the focused research priorities in each area followed by critical supporting science for biological enhancements as prioritized during the workshop. Finally, Table 1 summarizes the potential significance or 'materiality' of advances in these areas for reducing net greenhouse gas emissions.

  13. Enhanced biological phosphorus removal with different carbon sources.

    Science.gov (United States)

    Shen, Nan; Zhou, Yan

    2016-06-01

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

  14. The role of mesopores in MTBE removal with granular activated carbon.

    Science.gov (United States)

    Redding, Adam M; Cannon, Fred S

    2014-06-01

    This activated carbon research appraised how pore size and empty-bed contact time influenced the removal of methyl tert-butyl ether (MTBE) at part-per-billion (ppb) concentrations when MTBE was the sole organic impurity. The study compared six granular activated carbons (GACs) from three parent sources; these GACs contained a range of pore volume distributions and had uniform slurry pHs of 9.7-10.4 (i.e. the carbons' bulk surface chemistries were basic). Several of these activated carbons had been specifically tailored for enhanced sorption of trace organic compounds. In these tests, MTBE was spiked into deionized-distilled water (∼pH 7); MTBE loading was measured by isotherms and by rapid small-scale column tests (RSSCTs) that simulated full-scale empty-bed contact times of 7, 14, and 28 min. The results showed that both ultra-fine micropores and small-diameter mesopores were important for MTBE adsorption. Specifically, full MTBE loading during RSSCTs bore a strong correlation (R(2) = 0.94) to the product (mL/g × mL/g) of pore volume ≤4.06 Å wide and pore volume between ∼22 Å and ∼59 Å wide. This correlation was greater than for the product of any other pore volume combinations. Also, this product exhibited a stronger correlation than for just one or the other of these two pore ranges. This multiplicative relationship implied that both of these pore sizes were important for the optimum GAC performance of these six carbons (i.e. favorable mass transfer coupled with favorable sorption). The authors also compared MTBE mass loading during RSSCTs (μg MTBE/g GAC) to isotherm capacity (μg MTBE/g GAC). This RSSCT loading "efficiency" ranged from 28% to 96% for the six GACs; this efficiency correlated most strongly to pores that were 14-200 Å wide (R(2) = 0.94). This correlation indicated that only those carbons with a sufficient volume of 14-200 Å pores could adsorb MTBE to the extent that would be predicted from isotherm data. Copyright

  15. Carbon nanostructured surfaces for enhanced heat transport

    NARCIS (Netherlands)

    Taha, T.J.

    2015-01-01

    The advancement of high performance thermal systems has stimulated interest in methods to improve heat transfer rates. Considerable efforts have been made to increase heat transfer rates by implementing passive convective heat transfer enhancement methods that require no direct consumption of

  16. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    Energy Technology Data Exchange (ETDEWEB)

    Li Jiangling; Su Shi; Kundrat, Vojtech; Abbot, Andrew M.; Ye, Haitao [School of Engineering and Applied Science, Aston University, Birmingham B4 7ET (United Kingdom); Zhou Lei [Department of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT (United Kingdom); Mushtaq, Fajer [Department of Mechanical Engineering, ETH Zurich, Zurich 8092 (Switzerland); Ouyang Defang [School of Life and Health Science, Aston University, Birmingham B4 7ET (United Kingdom); James, David; Roberts, Darren [Thermo Fisher Scientific, Stafford House, Hemel Hempstead HP2 7GE (United Kingdom)

    2013-01-14

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  17. Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

    Science.gov (United States)

    Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

    2016-11-15

    The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  19. Effects of ozonation and temperature on biodegradation of natural organic matter in biological granular activated carbon filters

    NARCIS (Netherlands)

    Van der Aa, L.T.J.; Rietveld, L.C.; Van Dijk, J.C.

    2010-01-01

    Four pilot (biological) granular activated carbon ((B)GAC) filters were operated to quantify the effects of ozonation and water temperature on the biodegradation of natural organic matter (NOM) in (B)GAC filters. Removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and oxygen

  20. Effects of ozonation and temperature on the biodegradation of natural organic matter in biological granular activated carbon filters

    NARCIS (Netherlands)

    Van der Aa, L.T.J.; Rietveld, L.C.; Van Dijk, J.C.

    2011-01-01

    Four pilot (biological) granular activated carbon ((B)GAC) filters were operated to quantify the effects of ozonation and water temperature on the biodegradation of natural organic matter (NOM) in (B)GAC filters. The removal of dissolved organic carbon (DOC), assimilable organic carbon (AOC) and

  1. Cellulosic carbon fibers with branching carbon nanotubes for enhanced electrochemical activities for bioprocessing applications.

    Science.gov (United States)

    Zhao, Xueyan; Lu, Xin; Tze, William Tai Yin; Kim, Jungbae; Wang, Ping

    2013-09-25

    Renewable biobased carbon fibers are promising materials for large-scale electrochemical applications including chemical processing, energy storage, and biofuel cells. Their performance is, however, often limited by low activity. Herein we report that branching carbon nanotubes can enhance the activity of carbonized cellulosic fibers, such that the oxidation potential of NAD(H) was reduced to 0.55 V from 0.9 V when applied for bioprocessing. Coordinating with enzyme catalysts, such hierarchical carbon materials effectively facilitated the biotransformation of glycerol, with the total turnover number of NAD(H) over 3500 within 5 h of reaction.

  2. Open Letter from the GAC-EPA to the Chairman of the PFGB EPA

    CERN Multimedia

    GAC-EPA

    2012-01-01

    Following the publication by the Chairman of the Pension Fund Governing Board of  the Spring report of the Pension Fund in the CERN Bulletin issue dated 25 July 2012 (Nos 30 & 31), the GAC-EPA has reacted through an open letter. See www.gac-epa.org under Announcement.

  3. Carbon-enhanced metal-poor stars in different environments

    NARCIS (Netherlands)

    Salvadori, S.; Skúladóttir, Á.; de Bennassuti, M.

    2016-01-01

    The origin of carbon-enhanced metal-poor (CEMP) stars and their possible connections with the chemical elements produced by the first stellar generations is still highly debated. We briefly review observations of CEMP stars in different environments (Galactic stellar halo, ultra-faint, and classical

  4. Carbon-enhanced metal-poor stars in dwarf galaxies

    NARCIS (Netherlands)

    Salvadori, Stefania; Skúladóttir, Ása; Tolstoy, Eline

    2015-01-01

    We investigate the frequency and origin of carbon-enhanced metal-poor (CEMP) stars in Local Group dwarf galaxies by means of a statistical, data-calibrated cosmological model for the hierarchical build-up of the Milky Way and its dwarf satellites. The model self-consistently explains the variation

  5. Carbon Nanotube Bonding Strength Enhancement Using Metal "Wicking" Process

    Science.gov (United States)

    Lamb, James L.; Dickie, Matthew R.; Kowalczyk, Robert S.; Liao, Anna; Bronikowski, Michael J.

    2012-01-01

    Carbon nanotubes grown from a surface typically have poor bonding strength at the interface. A process has been developed for adding a metal coat to the surface of carbon nano tubes (CNTs) through a wicking process, which could lead to an enhanced bonding strength at the interface. This process involves merging CNTs with indium as a bump-bonding enhancement. Classical capillary theory would not normally allow materials that do not wet carbon or graphite to be drawn into the spacings by capillary action because the contact angle is greater than 90 degrees. However, capillary action can be induced through JPL's ability to fabricate oriented CNT bundles to desired spacings, and through the use of deposition techniques and temperature to control the size and mobility of the liquid metal streams and associated reservoirs. A reflow and plasma cleaning process has also been developed and demonstrated to remove indium oxide, and to obtain smooth coatings on the CNT bundles.

  6. Fenton-Driven Regeneration of MTBE-spent Granular Activated Carbon

    Science.gov (United States)

    Fenton-driven regeneration of Methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) involves the combined, synergistic use of two treatment technologies: adsorption of organic chemicals onto activated carbon and Fenton-driven oxidation regeneration of the spent-GAC...

  7. Carbon dioxide flooding as an enhanced oil recovery process

    Energy Technology Data Exchange (ETDEWEB)

    Mungan, N. (Alberta Energy Co. Ltd., AB (Canada))

    1992-11-01

    A description is presented of the state-of-the-art on carbon dioxide flooding and how it relates to recovery of heavy oils. Carbon dioxide flooding enhances recovery due to a number of mechanisms: reduction of oil viscosity, swelling of oil, vaporization of oil, miscibility effects, reduction of interfacial tension, solution gas drive, and increases in injectivity. Three types of reservoir are particularly well suited to carbon dioxide flooding: carbonate formations which may not have a high enough injectivity to make waterflooding successful; reservoirs containing undersaturated crude oils; and certain heavy oil reservoirs. A detailed description is presented of preparation for a field test, pressure-volume-temperature data for light and heavy crude oils, and a pilot testing of CO[sub 2] flooding. To the extent that it is possible, the pilot should closely represent the formation and fluid properties and the pressures that exist in the reservoir. 7 refs., 4 figs.

  8. Regulation of GacA in Pseudomonas chlororaphis Strains Shows a Niche Specificity.

    Directory of Open Access Journals (Sweden)

    Jun Li

    Full Text Available The GacS/GacA two-component system plays a central role in the regulation of a broad range of biological functions in many bacteria. In the biocontrol organism Pseudomonas chlororaphis, the Gac system has been shown to positively control quorum sensing, biofilm formation, and phenazine production, but has an overall negative impact on motility. These studies have been performed with strains originated from the rhizosphere predominantly. To investigate the level of conservation between the GacA regulation of biocontrol-related traits in P. chlororaphis isolates from different habitats, the studies presented here focused on the endophytic isolate G5 of P. chlororaphis subsp. aurantiaca. A gacA mutant deficient in the production of N-acylhomoserine lactones (AHLs and phenazine was isolated through transposon mutagenesis. Further phenotypic characterization revealed that in strain G5, similar to other P. chlororaphis strains, a gacA mutation caused inability to produce biocontrol factors such as phenazine, HCN and proteases responsible for antifungal activity, but overproduced siderophores. LC-MS/MS analysis revealed that AHL production was also practically abolished in this mutant. However, the wild type exhibited an extremely diverse AHL pattern which has never been identified in P. chlororaphis. In contrast to other isolates of this organism, GacA in strain G5 was shown to negatively regulate biofilm formation and oxidative stress response whilst positively regulating cell motility and biosynthesis of indole-3-acetic acid (IAA. To gain a better understanding of the overall impact of GacA in G5, a comparative proteomic analysis was performed revealing that, in addition to some of the traits like phenazine mentioned above, GacA also negatively regulated lipopolysaccharide (LPS and trehalose biosynthesis whilst having a positive impact on energy metabolism, an effect not previously described in P. chlororaphis. Consequently, GacA regulation shows a

  9. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    Science.gov (United States)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  10. A NOVEL APPROACH TO MINERAL CARBONATION: ENHANCING CARBONATION WHILE AVOIDING MINERAL PRETREATMENT PROCESS COST

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. McKelvy; Andrew V.G. Chizmeshya; Kyle Squires; Ray W. Carpenter; Hamadallah Bearat

    2005-10-01

    Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. Herein, we report our first year progress in exploring a novel approach that offers the potential to substantially enhance carbonation reactivity while bypassing pretreatment activation. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly-stirred/circulating carbonation. We are exploring the mechanisms that govern carbonation reactivity and the impact that (1) modeling/controlling the slurry fluid-flow conditions, (2) varying the

  11. A Novel Approach To Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost

    Energy Technology Data Exchange (ETDEWEB)

    Michael J. McKelvy; Andrew V. G. Chizmeshya; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

    2006-06-21

    Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. Herein, we report our second year progress in exploring a novel approach that offers the potential to substantially enhance carbonation reactivity while bypassing pretreatment activation. As our second year progress is intimately related to our earlier work, the report is presented in that context to provide better overall understanding of the progress made. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly

  12. A Novel Approach to Mineral Carbonation: Enhancing Carbonation While Avoiding Mineral Pretreatment Process Cost

    Energy Technology Data Exchange (ETDEWEB)

    Andrew V. G. Chizmeshya; Michael J. McKelvy; Kyle Squires; Ray W. Carpenter; Hamdallah Bearat

    2007-06-21

    Known fossil fuel reserves, especially coal, can support global energy demands for centuries to come, if the environmental problems associated with CO{sub 2} emissions can be overcome. Unlike other CO{sub 2} sequestration candidate technologies that propose long-term storage, mineral sequestration provides permanent disposal by forming geologically stable mineral carbonates. Carbonation of the widely occurring mineral olivine (e.g., forsterite, Mg{sub 2}SiO{sub 4}) is a large-scale sequestration process candidate for regional implementation, which converts CO{sub 2} into the environmentally benign mineral magnesite (MgCO{sub 3}). The primary goal is cost-competitive process development. As the process is exothermic, it inherently offers low-cost potential. Enhancing carbonation reactivity is key to economic viability. Recent studies at the U.S. DOE Albany Research Center have established that aqueous-solution carbonation using supercritical CO{sub 2} is a promising process; even without olivine activation, 30-50% carbonation has been achieved in an hour. Mechanical activation (e.g., attrition) has accelerated the carbonation process to an industrial timescale (i.e., near completion in less than an hour), at reduced pressure and temperature. However, the activation cost is too high to be economical and lower cost pretreatment options are needed. We have discovered that robust silica-rich passivating layers form on the olivine surface during carbonation. As carbonation proceeds, these passivating layers thicken, fracture and eventually exfoliate, exposing fresh olivine surfaces during rapidly-stirred/circulating carbonation. We are exploring the mechanisms that govern carbonation reactivity and the impact that (1) modeling/controlling the slurry fluid-flow conditions, (2) varying the aqueous ion species/size and concentration (e.g., Li+, Na+, K+, Rb+, Cl-, HCO{sub 3}{sup -}), and (3) incorporating select sonication offer to enhance exfoliation and carbonation. Thus

  13. Plasmonic enhancement of SERS measured on molecules in carbon nanotubes.

    Science.gov (United States)

    Mueller, Niclas S; Heeg, Sebastian; Kusch, Patryk; Gaufrès, Etienne; Tang, Nathalie Y-W; Hübner, Uwe; Martel, Richard; Vijayaraghavan, Aravind; Reich, Stephanie

    2017-12-04

    We isolated the plasmonic contribution to surface-enhanced Raman scattering (SERS) and found it to be much stronger than expected. Organic dyes encapsulated in single-walled carbon nanotubes are ideal probes for quantifying plasmonic enhancement in a Raman experiment. The molecules are chemically protected through the nanotube wall and spatially isolated from the metal, which prevents enhancement by chemical means and through surface roughness. The tubes carry molecules into SERS hotspots, thereby defining molecular position and making it accessible for structural characterization with atomic-force and electron microscopy. We measured a SERS enhancement factor of 106 on α-sexithiophene (6T) molecules in the gap of a plasmonic nanodimer. This is two orders of magnitude stronger than predicted by the electromagnetic enhancement theory (104). We discuss various phenomena that may explain the discrepancy (including hybridization, static and dynamic charge transfer, surface roughness, uncertainties in molecular position and orientation), but found all of them lacking in enhancement for our probe system. We suggest that plasmonic enhancement in SERS is, in fact, much stronger than currently anticipated. We discuss novel approaches for treating SERS quantum mechanically that appear promising for predicting correct enhancement factors. Our findings have important consequences on the understanding of SERS as well as for designing and optimizing plasmonic substrates.

  14. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  15. Operating considerations of ultrafiltration in enzyme enhanced carbon capture

    DEFF Research Database (Denmark)

    Deslauriers, Maria Gundersen; Gladis, Arne; Fosbøl, Philip Loldrup

    2017-01-01

    could be used. It was found that with enzyme retention of 99.9%, with instant deactivation, after 1 month 50% of the activity is lost. Thus the use of membranes in enzyme enhanced CCS might be restricted to temperatures below 100 °C, or temperatures the enzyme can withstand for shorter time periods.......Today, enzyme enhanced carbon capture and storage (CCS) is gaining interest, since it can enable the use of energy efficient solvents, and thus potentially reduce the carbon footprint of CCS. However, a limitation of this technology is the high temperatures encountered in the stripper column, which...... can deactivate the enzymes. One solution to this challenge is the use of ultrafiltration to retain the enzyme in the absorber unit. In this report, a base case of a CCS facility is used to model the impact of such membranes for use in a full scale CCS commercial plant. The base case has an approximate...

  16. Enhanced electrochemical activity using vertically aligned carbon nanotube electrodes grown on carbon fiber

    Directory of Open Access Journals (Sweden)

    Evandro Augusto de Morais

    2011-09-01

    Full Text Available Vertically aligned carbon nanotubes were successfully grown on flexible carbon fibers by plasma enhanced chemical vapor deposition. The diameter of the CNT is controllable by adjusting the thickness of the catalyst Ni layer deposited on the fiber. Vertically aligned nanotubes were grown in a Plasma Enhanced Chemical Deposition system (PECVD at a temperature of 630 ºC, d.c. bias of -600 V and 160 and 68 sccm flow of ammonia and acetylene, respectively. Using cyclic voltammetry measurements, an increase of the surface area of our electrodes, up to 50 times higher, was observed in our samples with CNT. The combination of VACNTs with flexible carbon fibers can have a significant impact on applications ranging from sensors to electrodes for fuel cells.

  17. Photochemical defluorination of aqueous perfluorooctanoic acid (PFOA) by Fe(0)/GAC micro-electrolysis and VUV-Fenton photolysis.

    Science.gov (United States)

    Zhang, Li-Hong; Cheng, Jian-Hua; You, Xia; Liang, Xiao-Yan; Hu, Yong-You

    2016-07-01

    Perfluorooctanoic acid (PFOA) is extremely persistent and bioaccumulative in the environment; thus, it is very urgent to investigate an effective and moderate technology to treat the pollution of PFOA. In this study, a process combined iron and granular activated carbon (Fe(0)/GAC) micro-electrolysis with VUV-Fenton system is employed for the remediation of PFOA. Approximately 50 % PFOA (10 mg L(-1)) could be efficiently defluorinated under the following conditions: pH 3.0, dosage of Fe 7.5 g L(-1), dosage of GAC 12.5 g L(-1), and concentration of H2O2 22.8 mmol L(-1). Meanwhile, during the process, evident defluorination was observed and the concentration of fluoride ion was eventually 3.23 mg L(-1). The intermediates including five shorter-chain perfluorinated carboxylic acids (PFCAs), i.e., C7, C6, C5, C4, and C3, were also analyzed by high-performance liquid chromatography tandem mass spectrometry (HPLC/MS/MS) and defluorination mechanisms of PFOA was proposed, which involved photochemical of OH·, direct photolysis (185-nm VUV), and photocatalytic degradation of PFOA in the presence of Fe(3+) (254-nm UV).

  18. Alignment enhanced photoconductivity in single wall carbon nanotube films

    Science.gov (United States)

    Liu, Ye; Lu, Shaoxin; Panchapakesan, Balaji

    2009-01-01

    In this paper we report, for the first time, the alignment enhanced photoconductivity of single wall carbon nanotube films upon laser illumination. The photoconductivity exhibited an increase, decrease or even 'negative' values when the laser spot was on different positions between contact electrodes, showing a 'position' dependent photoconductivity of partially aligned films of carbon nanotubes. Photon induced charge carrier generation in single wall carbon nanotubes and subsequent charge separation across the metal-carbon nanotube contacts is believed to cause the photoconductivity changes. A net photovoltage of ~4 mV and a photocurrent of ~10 µA were produced under the laser intensity of ~273 mW with a quantum efficiency of ~7.8% in vacuum. The photocurrent was observed to be in the direction of nanotube alignment. Finally, there was a strong dependence of the polarization of the incident light on the photocurrent and the orientation of the films influenced the dynamics of the rise and fall of the photocurrent. All of these phenomena clearly have significance in the area of design and fabrication of solar cells, micro-opto-mechanical systems and photodetectors based on carbon nanotubes.

  19. Enhancement of field emission characteristics of carbon nanotubes on oxidation.

    Science.gov (United States)

    Mathur, Ashish; Roy, Susanta Sinha; Ray, Sekhar Chandra; Hazra, Kiran Shankar; Hamilton, Jeremy; Dickinson, Calum; McLaughlin, James; Misra, Devi Shankar

    2011-08-01

    Vertically aligned multi-walled carbon nanotubes (CNTs) were grown on p-type silicon wafer using thermal chemical vapor deposition process and subsequently treated with oxygen plasma for oxidation. It was observed that the electron field emission (EFE) characteristics are enhanced. It showed that the turn-on electric field (E(TOE)) of CNTs decreased from 0.67 (untreated) to 0.26 V/microm (oxygen treated). Raman spectra showed that the numbers of defects are increased, which are generated by oxygen-treatment, and absorbed molecules on the CNTs are responsible for the enhancement of EFE. Scanning electron microscopy and Transmission electron microscopy images were used to identify the quality and physical changes of the nanotube morphology and surfaces; revealing the evidence of enhancement in the field emission properties after oxygen-plasma treatment.

  20. Reuse performance of granular-activated carbon and activated carbon fiber in catalyzed peroxymonosulfate oxidation.

    Science.gov (United States)

    Yang, Shiying; Li, Lei; Xiao, Tuo; Zhang, Jun; Shao, Xueting

    2017-03-01

    Recently, activated carbon was investigated as an efficient heterogeneous metal-free catalyst to directly activate peroxymonosulfate (PMS) for degradation of organic compounds. In this paper, the reuse performance and the possible deactivation reasons of granular-activated carbon (GAC) and activated carbon fiber (ACF) in PMS activation were investigated. As results indicated, the reusability of GAC, especially in the presence of high PMS dosage, was relatively superior to ACF in catalyzed PMS oxidation of Acid Orange 7 (AO7), which is much more easily adsorbed by ACF than by GAC. Pre-oxidation experiments were studied and it was demonstrated that PMS oxidation on ACF would retard ACF's deactivation to a big extent. After pre-adsorption with AO7, the catalytic ability of both GAC and ACF evidently diminished. However, when methanol was employed to extract the AO7-spent ACF, the catalytic ability could recover quite a bit. GAC and ACF could also effectively catalyze PMS to degrade Reactive Black 5 (RB5), which is very difficult to be adsorbed even by ACF, but both GAC and ACF have poor reuse performance for RB5 degradation. The original organic compounds or intermediate products adsorbed by GAC or ACF would be possibly responsible for the deactivation.

  1. Enhancing anaerobic digestion of poultry blood using activated carbon

    Directory of Open Access Journals (Sweden)

    Maria José Cuetos

    2017-05-01

    Full Text Available The potential of using anaerobic digestion for the treatment of poultry blood has been evaluated in batch assays at the laboratory scale and in a mesophilic semi-continuous reactor. The biodegradability test performed on residual poultry blood was carried out in spite of high inhibitory levels of acid intermediaries. The use of activated carbon as a way to prevent inhibitory conditions demonstrated the feasibility of attaining anaerobic digestion under extreme ammonium and acid conditions. Batch assays with higher carbon content presented higher methane production rates, although the difference in the final cumulative biogas production was not as sharp. The digestion of residual blood was also studied under semi-continuous operation using granular and powdered activated carbon. The average specific methane production was 216 ± 12 mL CH4/g VS. This result was obtained in spite of a strong volatile fatty acid (VFA accumulation, reaching values around 6 g/L, along with high ammonium concentrations (in the range of 6–8 g/L. The use of powdered activated carbon resulted in a better assimilation of C3-C5 acid forms, indicating that an enhancement in syntrophic metabolism may have taken place. Thermal analysis and scanning electron microscopy (SEM were applied as analytical tools for measuring the presence of organic material in the final digestate and evidencing modifications on the carbon surface. The addition of activated carbon for the digestion of residual blood highly improved the digestion process. The adsorption capacity of ammonium, the protection this carrier may offer by limiting mass transfer of toxic compounds, and its capacity to act as a conductive material may explain the successful digestion of residual blood as the sole substrate.

  2. Effect of pre-acclimation of granular activated carbon on microbial electrolysis cell startup and performance.

    Science.gov (United States)

    LaBarge, Nicole; Yilmazel, Yasemin Dilsad; Hong, Pei-Ying; Logan, Bruce E

    2017-02-01

    Microbial electrolysis cells (MECs) can generate methane by fixing carbon dioxide without using expensive catalysts, but the impact of acclimation procedures on subsequent performance has not been investigated. Granular activated carbon (GAC) was used to pre-enrich electrotrophic methanogenic communities, as GAC has been shown to stimulate direct transfer of electrons between different microbial species. MEC startup times using pre-acclimated GAC were improved compared to controls (without pre-acclimation or without GAC), and after three fed batch cycles methane generation rates were similar (P>0.4) for GAC acclimated to hydrogen (22±9.3nmolcm -3 d -1 ), methanol (25±9.7nmolcm -3 d -1 ), and a volatile fatty acid (VFA) mix (22±11nmolcm -3 d -1 ). However, MECs started with GAC but no pre-acclimation had lower methane generation rates (13±4.1nmolcm -3 d -1 ), and MECs without GAC had the lowest rates (0.7±0.8nmolcm -3 d -1 after cycle 2). Microbes previously found in methanogenic MECs, or previously shown to be capable of exocellular electron transfer, were enriched on the GAC. Pre-acclimation using GAC is therefore a simple approach to enrich electroactive communities, improve methane generation rates, and decrease startup times in MECs. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Iron optimization for Fenton-driven oxidation of MTBE-spent granular activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Scott G. Huling; Patrick K. Jones; Tony R. Lee [U.S. Environmental Protection Agency, Ada, OK (United States). Office of Research and Development, National Risk Management Research Laboratory

    2007-06-01

    Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was accomplished through the addition of iron (Fe) and hydrogen peroxide (H{sub 2}O{sub 2}) (15.9 g/L; pH 3). The GAC used was URV, a bituminous-coal based carbon. The Fe concentration in GAC was incrementally varied (1020-25 660 mg/kg) by the addition of increasing concentrations of Fe solution (FeSO4{center_dot}7H{sub 2}O). MTBE degradation in Fe-amended GAC increased by an order of magnitude over Fe-unamended GAC and H{sub 2}O{sub 2} reaction was predominantly (99%) attributed to GAC-bound Fe within the porous structure of the GAC. Imaging and microanalysis of GAC particles indicated limited penetration of Fe into GAC. The optimal Fe concentration was 6710 mg/kg (1020 mg/kg background; 5690 mg/kg amended Fe) and resulted in the greatest MTBE removal and maximum Fe loading oxidation efficiency (MTBE oxidized (g)/Fe loaded to GAC(mg/Kg)). At lower Fe concentrations, the H{sub 2}O{sub 2} reaction was Fe limited. At higher Fe concentrations, the H{sub 2}O{sub 2} reaction was not entirely Fe limited, and reductions in GAC surface area, GAC pore volume, MTBE adsorption, and Fe loading oxidation efficiency were measured. Results are consistent with nonuniform distribution of Fe, pore blockage in H{sub 2}O{sub 2} transport, unavailable Fe, and limitations in H{sub 2}O{sub 2} diffusive transport, and emphasize the importance of optimal Fe loading. 22 refs., 6 figs., 2 tabs.

  4. Toluene removal from waste air stream by the catalytic ozonation process with MgO/GAC composite as catalyst.

    Science.gov (United States)

    Rezaei, Fatemeh; Moussavi, Gholamreza; Bakhtiari, Alireza Riyahi; Yamini, Yadollah

    2016-04-05

    This paper investigates the catalytic potential of MgO/GAC composite for toluene elimination from waste air in the catalytic ozonation process (COP). The MgO/GAC composite was a micro-porous material with the BET surface area of 1082m(2)/g. Different functional groups including aromatic CC, saturated CO of anhydrates, hydroxyl groups and SH bond of thiols were identified on the surface of MgO/GAC. Effects of residence time (0.5-4s), inlet toluene concentration (100-400ppmv) and bed temperature (25-100°C) were investigated on degradation of toluene in COP. Impregnation of GAC with MgO increased the breakthrough time and removal capacity by 73.9% and 64.6%, respectively, at the optimal conditions. The catalytic potential of the GAC and MgO/GAC for toluene degradation was 11.1% and 90.6%, respectively, at the optimum condition. The highest removal capacity using MgO/GAC (297.9gtoulene/gMgO/GAC) was attained at 100°C, whereas the highest removal capacity of GAC (128.5mgtoulene/gGAC) was obtained at 25°C. Major by-products of the toluene removal in COP with GAC were Formic acid, benzaldehyde, O-nitro-p-cresol and methyl di-phenyl-methane. MgO/GAC could greatly catalyze the decomposition of toluene in COPand formic acid was the main compound desorbed from the catalyst. Accordingly, the MgO/GAC is an efficient material to catalyze the ozonation of hydrocarbon vapors. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Bioaugmented membrane bioreactor (MBR) with a GAC-packed zone for high rate textile wastewater treatment.

    Science.gov (United States)

    Hai, Faisal Ibney; Yamamoto, Kazuo; Nakajima, Fumiyuki; Fukushi, Kensuke

    2011-03-01

    The long-term performance of a bioaugmented membrane bioreactor (MBR) containing a GAC-packed anaerobic zone for treatment of textile wastewater containing structurally different azo dyes was observed. A unique feeding strategy, consistent with the mode of evolution of separate waste streams in textile plants, was adopted to make the best use of the GAC-zone for dye removal. Dye was introduced through the GAC-zone while the rest of the colorless media was simultaneously fed through the aerobic zone. Preliminary experiments confirmed the importance of coupling the GAC-amended anaerobic zone to the aerobic MBR and also evidenced the efficacy of the adopted feeding strategy. Following this, the robustness of the process under gradually increasing dye-loading was tested. The respective average dye concentrations (mg/L) in the sample from GAC-zone and the membrane-permeate under dye-loadings of 0.1 and 1 g/L.d were as follows: GAC-zone (3, 105), permeate (0, 5). TOC concentration in membrane-permeate for the aforementioned loadings were 3 and 54 mg/L, respectively. Stable decoloration along with significant TOC removal during a period of over 7 months under extremely high dye-loadings demonstrated the superiority of the proposed hybrid process. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Enhanced graphitization of carbon around carbon nanotubes during the formation of carbon nanotube/graphite composites by pyrolysis of carbon nanotube/polyaniline composites.

    Science.gov (United States)

    Nam, Dong Hoon; Cha, Seung Il; Jeong, Yong Jin; Hong, Soon Hyung

    2013-11-01

    The carbon nanotubes (CNTs) are actively applied to the reinforcements for composite materials during last decade. One of the attempts is development of CNT/Carbon composites. Although there are some reports on the enhancement of mechanical properties by addition of CNTs in carbon or carbon fiber, it is far below the expectation. Considering the microstructure of carbon materials such as carbon fiber, the properties of them can be modified and enhanced by control of graphitization and alignment of graphene planes. In this study, enhanced graphitization of carbon has been observed the vicinity of CNTs during the pyrolysis of CNT/Polyaniline composites. As a result, novel types of composite, consisting of treading CNTs and coated graphite, can be fabricated. High-resolution transmission electron microscopy revealed a specific orientation relationship between the graphene layers and the CNTs, with an angle of 110 degrees between the layers and the CNT axis. The possibility of graphene alignment control in the carbon by the addition of CNTs is demonstrated.

  7. Kinetics of hydrophobic organic contaminant extraction from sediment by granular activated carbon

    NARCIS (Netherlands)

    Rakowska, M.I.; Kupryianchyk, D.; Smit, M.; Koelmans, A.A.; Meent, van de D.

    2014-01-01

    Ex situ solid phase extraction with granular activated carbon (GAC) is a promising technique to remediate contaminated sediments. The methods' efficiency depends on the rate by which contaminants are transferred from the sediment to the surface of GAC. Here, we derive kinetic parameters for

  8. In-Situ Regeneration of Saturated Granular Activated Carbon by an Iron Oxide Nanocatalyst

    Science.gov (United States)

    Granular activated carbon (GAC) can remove trace organic pollutants and natural organic matter (NOM) from industrial and municipal waters. This paper evaluates an iron nanocatalyst approach, based on Fenton-like oxidation reactions, to regenerate spent GAC within a packed bed con...

  9. Persulfate Oxidation Regeneration of Granular Activated Carbon: Reversible Impacts on Sorption Behavior

    Science.gov (United States)

    Chemical oxidation regeneration of granular activated carbon (GAC) is a developing technology that can be carried out utilizing thermally-activated persulfate. During chemical regeneration of GAC, aggressive oxidative conditions lead to high acidity (pH < 2) and the accumulation ...

  10. Hierarchical Nafion enhanced carbon aerogels for sensing applications.

    Science.gov (United States)

    Weng, Bo; Ding, Ailing; Liu, Yuqing; Diao, Jianglin; Razal, Joselito; Lau, King Tong; Shepherd, Roderick; Li, Changming; Chen, Jun

    2016-02-14

    This work describes the fabrication of hierarchical 3D Nafion enhanced carbon aerogels (NECAGs) for sensing applications via a fast freeze drying method. Graphene oxide, multiwalled carbon nanotubes and Nafion were mixed and extruded into liquid nitrogen followed by the removal of ice crystals by freeze drying. The addition of Nafion enhanced the mechanical strength of NECAGs and effective control of the cellular morphology and pore size was achieved. The resultant NECAGs demonstrated high strength, low density, and high specific surface area and can achieve a modulus of 20 kPa, an electrical conductivity of 140 S m(-1), and a specific capacity of 136.8 F g(-1) after reduction. Therefore, NECAG monoliths performed well as a gas sensor and as a biosensor with high sensitivity and selectivity. The remarkable sensitivity of 8.52 × 10(3)μA mM(-1) cm(-2) was obtained in dopamine (DA) detection, which is two orders of magnitude better than the literature reported values using graphene aerogel electrodes made from a porous Ni template. These outstanding properties make the NECAG a promising electrode candidate for a wide range of applications. Further in-depth investigations are being undertaken to probe the structure-property relationship of NECAG monoliths prepared under various conditions.

  11. Enhancing the Ocean's Role in Carbon Dioxide Mitigation

    Science.gov (United States)

    Rau, G. H.

    2007-12-01

    Fossil fuels will likely remain the world's primary energy source for the foreseeable future. Practical, cost- effective, and safe means of significantly reducing fossil energy's CO2 footprint are therefore needed in order to avoid potentially catastrophic climate and environmental impacts. While considerable R&D effort is being invested in fossil fuel CO2 capture and storage above and below ground, the use of Earth's biggest single CO2 absorber and reservoir, the ocean, remains largely unexplored. For example, the US Department of Energy, lead agency in carbon management, has abandoned all ocean carbon research. This is risky and unwise because it forces global CO2 mitigation efforts to focus on only 30% of the earth's surface, ignoring most of the CO2 storage capacity of the planet. In addition to ocean storage of molecular CO2 that is captured from point sources on land, a variety of enhancements to natural marine biotic or abiotic CO2 uptake and sequestration have been proposed. These include increasing the chemical CO2 absorption of the ocean though the addition of alkalinity, or the addition of micro- or macro-nutrients to enhance photosynthetic CO2 uptake and storage. Potentially less impactful schemes include reacting CO2 with wet limestone to form calcium bicarbonate for subsequent ocean storage, or harvesting agricultural residue for long-term sequestration in anoxic ocean sediments. In many instances the cost/benefit of these approaches appear to be quite favorable, but further evaluation is needed, while additional ideas for ocean-based mitigation should be solicited. It is becoming clear that no one mitigation strategy will single-handedly stabilize atmospheric CO2, and the best strategies may ultimately bear little resemblance to those currently favored. Therefore, at this early stage we should not a priori ignore 70% of the earth's surface and a major component of the planet's carbon cycle in addressing the CO2 problem.

  12. The Regeneration of Granular Activated Carbon Using Hydrothermal Technology

    National Research Council Canada - National Science Library

    Sufnarski, Michael

    1999-01-01

    The economic feasibility of using granular activated carbon (GAC) to remove organic contaminants from industrial and municipal wastewater is contingent upon its reuse during multiple adsorption-regeneration cycles (Van Vliet, 1991...

  13. Design of Low Cost, Highly Adsorbent Activated Carbon Fibers

    National Research Council Canada - National Science Library

    Mangun, Christian

    2003-01-01

    .... EKOS has developed a novel activated carbon fiber - (ACF) that combines the low cost and durability of GAC with tailored pore size and pore surface chemistry for improved defense against chemical agents...

  14. Modification of granular activated carbon surface by chitosan coating for geosmin removal: sorption performances.

    Science.gov (United States)

    Vinitnantharat, S; Rattanasirisophon, W; Ishibashi, Y

    2007-01-01

    This study presents the results of the sorption performances for geosmin removal by sorption onto granular activated carbons (GAC) manufactured from different raw materials of coconut shell and bituminous coal. The surface of GAC was modified by chitosan coating. The 90% deacetylated chitosan flakes were used for coating on GAC with the GAC: chitosan ratio of 5:1. The surface of GAC was characterised by scanning electron microscope (SEM) analysis, Fourier transform infrared spectroscopy and measurement of the pH solution of GAC samples. The sorption of geosmin onto the chitosan for both uncoated and coated GACs could be described by the Freundlich adsorption model. Data revealed that the sequence of Freundlich constant (K(F)) was chitosan coated bitominous coal (CB) > uncoated bituminous coal (UB) > chitos approximately equal to an coated coconut shell (CC) approximately equal to uncoated coconut shell (UC). The bituminous coal based GAC with chitosan coating had a maximum capacity of 23.57 microg/g which was approximately two-fold of uncoated bituminous coal based GAC. Two simplified kinetic models, pseudo-first order and pseudo-second order, were tested to investigate the sorption mechanisms. It was found that the intraparticle diffusion was a rate controlling step for the sorption and followed the pseudo-second order equation.

  15. How conservation agriculture can mitigate greenhouse gas emissions and enhance soil carbon storage in croplands

    Science.gov (United States)

    Conservation agriculture can mitigate greenhouse gas (GHG) emissions from agriculture by enhancing soil carbon sequestration, improving soil quality, N-use efficiency and water use efficiencies, and reducing fuel consumption. Management practices that increase carbon inputs and while reducing carbo...

  16. Enhancing the Global Carbon Sink: A Key Mitigation Strategy

    Science.gov (United States)

    Torn, M. S.

    2016-12-01

    Earth's terrestrial ecosystems absorb about one-third of all anthropogenic CO2 emissions from the atmosphere each year, greatly reducing the climate forcing those emissions would otherwise cause. This puts the size of the terrestrial carbon sink on par with the most aggressive climate mitigation measures proposed. Moreover, the land sink has been keeping pace with rising emissions and has roughly doubled over the past 40 years. But there is a fundamental lack of understanding of why the sink has been increasing and what its future trajectory could be. In developing climate mitigation strategies, governments have a very limited scientific basis for projecting the contributions of their domestic sinks, and yet at least 117 of the 160 COP21 signatories stated they will use the land sink in their Nationally Defined Contribution (NDC). Given its potentially critical role in reducing net emissions and the importance of UNFCCC land sinks in future mitigation scenarios, a first-principles understanding of the dynamics of the land sink is needed. For expansion of the sink, new approaches and ecologically-sound technologies are needed. Carefully conceived terrestrial carbon sequestration could have multiple environmental benefits, but a massive expansion of land carbon sinks using conventional approaches could place excessive demands on the world's land, water, and fertilizer nutrients. Meanwhile, rapid climatic change threatens to undermine or reverse the sink in many ecosystems. We need approaches to protect the large sinks that are currently assumed useful for climate mitigation. Thus we highlight the need for a new research agenda aimed at predicting, protecting, and enhancing the global carbon sink. Key aspects of this agenda include building a predictive capability founded on observations, theory and models, and developing ecological approaches and technologies that are sustainable and scalable, and potentially provide co-benefits such as healthier soils, more

  17. Enhancement of Ultrahigh Performance Concrete Material Properties with Carbon Nanofiber

    Directory of Open Access Journals (Sweden)

    Libya Ahmed Sbia

    2014-01-01

    Full Text Available Ultrahigh performance concrete (UHPC realized distinctly high mechanical, impermeability, and durability characteristics by reducing the size and content of capillary pore, refining the microstructure of cement hydrates, and effectively using fiber reinforcement. The dense and fine microstructure of UHPC favor its potential to effectively disperse and interact with nanomaterials, which could complement the reinforcing action of fibers in UHPC. An optimization experimental program was implemented in order to identify the optimum combination of steel fiber and relatively low-cost carbon nanofiber in UHPC. The optimum volume fractions of steel fiber and carbon nanofiber identified for balanced improvement of flexural strength, ductility, energy sorption capacity, impact, and abrasion resistance of UHPC were 1.1% and 0.04%, respectively. Desired complementary/synergistic actions of nanofibers and steel fibers in UHPC were detected, which were attributed to their reinforcing effects at different scales, and the potential benefits of nanofibers to interfacial bonding and pull-out behavior of fibers in UHPC. Modification techniques which enhanced the hydrophilicity and bonding potential of nanofibers to cement hydrates benefited their reinforcement efficiency in UHPC.

  18. Carbon Nanotube-based microelectrodes for enhanced detection of neurotransmitters

    Science.gov (United States)

    Jacobs, Christopher B.

    Fast-scan cyclic voltammetry (FSCV) is one of the common techniques used for rapid measurement of neurotransmitters in vivo. Carbon-fiber microelectrodes (CFMEs) are typically used for neurotransmitter detection because of sub-second measurement capabilities, ability to measure changes in neurotransmitter concentration during neurotransmission, and the small size electrode diameter, which limits the amount of damage caused to tissue. Cylinder CFMEs, typically 50 -- 100 microm long, are commonly used for in vivo experiments because the electrode sensitivity is directly related to the electrode surface area. However the length of the electrode can limit the spatial resolution of neurotransmitter detection, which can restrict experiments in Drosophila and other small model systems. In addition, the electrode sensitivity toward dopamine and serotonin detection drops significantly for measurements at rates faster than 10 Hz, limiting the temporal resolution of CFMEs. While the use of FSCV at carbon-fiber microelectrodes has led to substantial strides in our understanding of neurotransmission, techniques that expand the capabilities of CFMEs are crucial to fully maximize the potential uses of FSCV. This dissertation introduces new methods to integrate carbon nanotubes (CNT) into microelectrodes and discusses the electrochemical enhancements of these CNT-microelectrodes. The electrodes are specifically designed with simple fabrication procedures so that highly specialized equipment is not necessary, and they utilize commercially available materials so that the electrodes could be easily integrated into existing systems. The electrochemical properties of CNT modified CFMEs are characterized using FSCV and the effect of CNT functionalization on these properties is explored in Chapter 2. For example, CFME modification using carboxylic acid functionalized CNTs yield about a 6-fold increase in dopamine oxidation current, but modification with octadecylamine CNTs results in a

  19. Patrones fenologico de la provincia de Mendoza, Argentina : Mediante serie temporal de imágenes NOAA - AVHRR NDI GAC

    NARCIS (Netherlands)

    González Loyarte, M.M.; Menenti, M.; Roig, F.A.

    2010-01-01

    Phenological patterns of the province of Mendoza, Argentina, through a temporal series of NOAA-AVHRR NDVI GAC images. The temporal dynamics of vegetation in Mendoza is described through analysis of regional foliar phenology using a series of 108 monthly NOAA-AVHRR NDVI GAC images. A Fast Fourier

  20. Effect of humic acid on pyrene removal from water by polycation-clay mineral composites and activated carbon.

    Science.gov (United States)

    Radian, Adi; Mishael, Yael

    2012-06-05

    Pyrene removal by polycation-montmorillonite (MMT) composites and granulated activated carbon (GAC) in the presence of humic acid (HA) was examined. Pyrene, HA, and sorbent interactions were characterized by FTIR, fluorescence and zeta measurements, adsorption, and column filtration experiments. Pyrene binding coefficients to the macromolecules were in the order of PVPcoS (poly-4-vinylpiridine-co-styrene) > HA > PDADMAC (poly diallyl-dimethyl-ammonium-chloride), correlating to pyrene-macromolecules compatibility. Electrostatic interactions explained the high adsorption of HA to both composites (∼100%), whereas HA adsorption by GAC was low. Pyrene removal by the composites, unlike GAC, was enhanced in the presence of HA; removal by PDADMAC-MMT increased from ∼50 (k(d) = 2.2 × 10(3) kg/L) to ∼70% (k(d) = 2.4 × 10(3) kg/L) in the presence of HA. This improvement was attributed to the adsorption of pyrene-HA complexes. PVPcoS-MMT was most efficient in removing pyrene (k(d) = 1.1 × 10(4) kg/L, >95% removal) which was explained in terms of specific π donor-π acceptor interactions. Pyrene uptake by column filters of GAC reached ∼50% and decreased to ∼30% in the presence of HA. Pyrene removal by the PVPcoS-MMT filter was significantly higher (100-85% removal), exhibiting only a small decrease in the presence of HA. The utilization of HA as an enhancing agent in pollutant removal is novel and of major importance in water treatment.

  1. Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene.

    Science.gov (United States)

    Tseng, Hui-Hsin; Su, Jhih-Gang; Liang, Chenju

    2011-08-30

    The coupling adsorption and degradation of trichloroethylene (TCE) through dechlorination using synthetic granular activated carbon and zerovalent iron (GAC-ZVI) composites was studied. The GAC-ZVI composites were prepared from aqueous Fe(2+) solutions by impregnation with and without the use of a PEG dispersant and then heated at 105°C or 700°C under a stream of N(2). Pseudo-first-order rate constant data on the removal of TCE demonstrates that the adsorption kinetics of GAC is similar to those of GAC-ZVI composites. However, the usage of GAC-ZVI composites liberated a greater amount of Cl than when ZVI was used alone. The highest degree of reductive dechlorination of TCE was achieved using a GAC-ZVI700P composite (synthesized using PEG under 700°C). A modified Langmuir-Hinshelwood rate law was employed to depict the behavior of Cl liberation. As a result, a zero-order Cl liberation reaction was observed and the desorption limited TCE degradation rate constant decreased as the composite dosage was increased. The GAC-ZVI composites can be employed as a reactive GAC that is not subject to the limitations of using GAC and ZVI separately. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. AVHRR GAC SST Reanalysis Version 1 (RAN1

    Directory of Open Access Journals (Sweden)

    Alexander Ignatov

    2016-04-01

    Full Text Available In response to its users’ needs, the National Oceanic and Atmospheric Administration (NOAA initiated reanalysis (RAN of the Advanced Very High Resolution Radiometer (AVHRR Global Area Coverage (GAC; 4 km sea surface temperature (SST data employing its Advanced Clear Sky Processor for Oceans (ACSPO retrieval system. Initially, AVHRR/3 data from five NOAA and two Metop satellites from 2002 to 2015 have been reprocessed. The derived SSTs have been matched up with two reference SSTs—the quality controlled in situ SSTs from the NOAA in situ Quality Monitor (iQuam and the Canadian Meteorological Centre (CMC L4 SST analysis—and analyzed in the NOAA SST Quality Monitor (SQUAM online system. The corresponding clear-sky ocean brightness temperatures (BT in AVHRR bands 3b, 4 and 5 (centered at 3.7, 11, and 12 µm, respectively have been compared with the Community Radiative Transfer Model simulations in another NOAA online system, Monitoring of Infrared Clear-sky Radiances over Ocean for SST (MICROS. For some AVHRRs, the time series of “AVHRR minus reference” SSTs and “observed minus model” BTs are unstable and inconsistent, with artifacts in the SSTs and BTs strongly correlated. In the official “Reanalysis version 1” (RAN1, data from only five platforms—two midmorning (NOAA-17 and Metop-A and three afternoon (NOAA-16, -18 and -19—were included during the most stable periods of their operations. The stability of the SST time series was further improved using variable regression SST coefficients, similarly to how it was done in the NOAA/NASA Pathfinder version 5.2 (PFV5.2 dataset. For data assimilation applications, especially those blending satellite and in situ SSTs, we recommend bias-correcting the RAN1 SSTs using the newly developed sensor-specific error statistics (SSES, which are reported in the product files. Relative performance of RAN1 and PFV5.2 SSTs is discussed. Work is underway to improve the calibration of AVHRR/3s and

  3. Carbon Dioxide-Water Emulsions for Enhanced Oil Recovery and Permanent Sequestration of Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, David; Golomb, Dan; Shi, Guang; Shih, Cherry; Lewczuk, Rob; Miksch, Joshua; Manmode, Rahul; Mulagapati, Srihariraju; Malepati, Chetankurmar

    2011-09-30

    This project involves the use of an innovative new invention Particle Stabilized Emulsions (PSEs) of Carbon Dioxide-in-Water and Water-in-Carbon Dioxide for Enhanced Oil Recovery (EOR) and Permanent Sequestration of Carbon Dioxide. The EOR emulsion would be injected into a semi-depleted oil reservoir such as Dover 33 in Otsego County, Michigan. It is expected that the emulsion would dislocate the stranded heavy crude oil from the rock granule surfaces, reduce its viscosity, and increase its mobility. The advancing emulsion front should provide viscosity control which drives the reduced-viscosity oil toward the production wells. The make-up of the emulsion would be subsequently changed so it interacts with the surrounding rock minerals in order to enhance mineralization, thereby providing permanent sequestration of the injected CO{sub 2}. In Phase 1 of the project, the following tasks were accomplished: 1. Perform laboratory scale (mL/min) refinements on existing procedures for producing liquid carbon dioxide-in-water (C/W) and water-in-liquid carbon dioxide (W/C) emulsion stabilized by hydrophilic and hydrophobic fine particles, respectively, using a Kenics-type static mixer. 2. Design and cost evaluate scaled up (gal/min) C/W and W/C emulsification systems to be deployed in Phase 2 at the Otsego County semi-depleted oil field. 3. Design the modifications necessary to the present CO{sub 2} flooding system at Otsego County for emulsion injection. 4. Design monitoring and verification systems to be deployed in Phase 2 for measuring potential leakage of CO{sub 2} after emulsion injection. 5. Design production protocol to assess enhanced oil recovery with emulsion injection compared to present recovery with neat CO{sub 2} flooding. 6. Obtain Federal and State permits for emulsion injection. Initial research focused on creating particle stabilized emulsions with the smallest possible globule size so that the emulsion can penetrate even low-permeability crude

  4. Enhanced decomposition offsets enhanced productivity and soil carbon accumulation in coastal wetlands responding to climate change

    Directory of Open Access Journals (Sweden)

    M. L. Kirwan

    2011-04-01

    Full Text Available Coastal wetlands are responsible for about half of all carbon burial in oceans, and their persistence as a valuable ecosystem depends largely on the ability to accumulate organic material at rates equivalent to relative sea level rise. Recent work suggests that elevated CO2 and temperature warming will increase organic matter productivity and the ability of marshes to survive sea level rise. However, we find in a series of preliminary experiments that organic decomposition rates increase by about 20% per degree of warming. Our measured temperature sensitivity is similar to studies from terrestrial systems, three times as high as the response of salt marsh productivity to temperature warming, and greater than the productivity response associated with elevated CO2 in C3 marsh plants. Although the experiments were simple and of short duration, they suggest that enhanced CO2 and warmer temperatures could actually make marshes less resilient to sea level rise, and tend to promote a release of soil carbon. Simple projections indicate that elevated temperatures will increase rates of sea level rise more than any acceleration in organic matter accumulation, suggesting the possibility of a positive feedback between climate, sea level rise, and carbon emissions in coastal environments.

  5. Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor

    NARCIS (Netherlands)

    Racyte, J.; Langenhoff, A.A.M.; Ribeiro, A.F.M.M.R.; Paulitsch-Fuchs, A.H.; Bruning, H.; Rijnaarts, H.

    2014-01-01

    Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency

  6. Effects of temperature on adsorption and oxidative degradation of bisphenol A in an acid-treated iron-amended granular activated carbon

    Science.gov (United States)

    The present study suggests a combined adsorption and Fenton oxidation using an acid treated Fe-amended granular activated carbon (Fe-GAC) for effective removal of bisphenol A in water. When the Fe-GAC adsorbs and is saturated with BPA in water, Fenton oxidation of BPA occurs in ...

  7. Enhancing thermal conductivity of fluids with graphite nanoparticles and carbon nanotube

    Science.gov (United States)

    Zhang, Zhiqiang [Lexington, KY; Lockwood, Frances E [Georgetown, KY

    2008-03-25

    A fluid media such as oil or water, and a selected effective amount of carbon nanomaterials necessary to enhance the thermal conductivity of the fluid. One of the preferred carbon nanomaterials is a high thermal conductivity graphite, exceeding that of the neat fluid to be dispersed therein in thermal conductivity, and ground, milled, or naturally prepared with mean particle size less than 500 nm, and preferably less than 200 nm, and most preferably less than 100 nm. The graphite is dispersed in the fluid by one or more of various methods, including ultrasonication, milling, and chemical dispersion. Carbon nanotubes with graphitic structure is another preferred source of carbon nanomaterial, although other carbon nanomaterials are acceptable. To confer long term stability, the use of one or more chemical dispersants is preferred. The thermal conductivity enhancement, compared to the fluid without carbon nanomaterial, is proportional to the amount of carbon nanomaterials (carbon nanotubes and/or graphite) added.

  8. Host-Guest Carbon Dots for Enhanced Optical Properties and Beyond

    OpenAIRE

    Ya-Ping Sun; Ping Wang; Zhuomin Lu; Fan Yang; Meziani, Mohammed J.; Gregory E. LeCroy; Yun Liu; Haijun Qian

    2015-01-01

    Carbon dots, generally small carbon nanoparticles with various forms of surface passivation, have achieved the performance level of semiconductor quantum dots in the green spectral region, but their absorption and fluorescence in red/near-IR are relatively weaker. Conceptually similar to endofullerenes, host-guest carbon dots were designed and prepared with red/near-IR dyes encapsulated as guest in the carbon nanoparticle core. Beyond the desired enhancement in optical properties, the host-gu...

  9. Origins of carbon-enhanced metal-poor stars

    Science.gov (United States)

    Sharma, Mahavir; Theuns, Tom; Frenk, Carlos S.; Cooke, Ryan J.

    2018-01-01

    We investigate the nature of carbon-enhanced metal-poor (CEMP) stars in Milky Way (MW) analogues selected from the EAGLE cosmological hydrodynamical simulation. The stellar evolution model in EAGLE includes the physics of enrichment by asymptotic giant branch (AGB) stars, winds from massive stars, and Type Ia and Type II supernovae (SNe). In the simulation, star formation in young MW progenitors is bursty due to efficient stellar feedback, which enables poor metal mixing leading to the formation of CEMP stars with extreme abundance patterns. Two classes of CEMP stars emerge: those mostly enriched by low-metallicity Type II SNe with low Fe yields that drive galactic outflows, and those mostly enriched by AGB stars when a gas-poor galaxy accretes pristine gas. The first class resembles CEMP-no stars with high [C/Fe] and low [C/O], the second class resembles CEMP-s stars overabundant in s-process elements and high values of [C/O]. These two enrichment channels explain several trends seen in data: (i) the increase in the scatter and median of [C/O] at low and decreasing [O/H], (ii) the trend of stars with very low [Fe/H] or [C/H] to be of type CEMP-no and (iii) the reduction in the scatter of [α/Fe] with atomic number in metal-poor stars. In this interpretation, CEMP-no stars were enriched by the stars that enabled galaxies to reionize the Universe.

  10. Carbon nanotubes enhance cytotoxicity mediated by human lymphocytes in vitro.

    Directory of Open Access Journals (Sweden)

    Zhao Sun

    Full Text Available With the expansion of the potential applications of carbon nanotubes (CNT in biomedical fields, the toxicity and biocompatibility of CNT have become issues of growing concern. Since the immune system often mediates tissue damage during pathogenesis, it is important to explore whether CNT can trigger cytotoxicity through affecting the immune functions. In the current study, we evaluated the influence of CNT on the cytotoxicity mediated by human lymphocytes in vitro. The results showed that while CNT at low concentrations (0.001 to 0.1 µg/ml did not cause obvious cell death or apoptosis directly, it enhanced lymphocyte-mediated cytotoxicity against multiple human cell lines. In addition, CNT increased the secretion of IFN-γ and TNF-α by the lymphocytes. CNT also upregulated the NF-κB expression in lymphocytes, and the blockage of the NF-κB pathway reduced the lymphocyte-mediated cytotoxicity triggered by CNT. These results suggest that CNT at lower concentrations may prospectively initiate an indirect cytotoxicity through affecting the function of lymphocytes.

  11. Studies on Enhancing Transverse Thermal Conductivity in Carbon/Carbon Composites

    National Research Council Canada - National Science Library

    Manocha, Lalit M

    2008-01-01

    ...) on a large scale in the form of aligned carbon nanotubes as arrays. Arrays of these carbon nanotubes were densified, like in carbon felt densification process by filling the space within the nanotube...

  12. Removal of nitrate from water by adsorption onto zinc chloride treated activated carbon

    DEFF Research Database (Denmark)

    Bhatnagar, A.; Ji, M.; Choi, Y.H.

    2008-01-01

    Adsorption study with untreated and zinc chloride (ZnCl2) treated coconut granular activated carbon (GAC) for nitrate removal from water has been carried out. Untreated coconut GAC was treated with ZnCl2 and carbonized. The optimal conditions were selected by studying the influence of process...... variables such as chemical ratio and activation temperature. Experimental results reveal that chemical weight ratio of 200% and temperature of 500 degrees C was found to be optimum for the maximum removal of nitrate from water. Both untreated and ZnCl2 treated coconut GACs were characterized by scanning...

  13. Enhanced Activated Carbon Cathode Performance for Microbial Fuel Cell by Blending Carbon Black

    KAUST Repository

    Zhang, Xiaoyuan

    2014-02-04

    Activated carbon (AC) is a useful and environmentally sustainable catalyst for oxygen reduction in air-cathode microbial fuel cells (MFCs), but there is great interest in improving its performance and longevity. To enhance the performance of AC cathodes, carbon black (CB) was added into AC at CB:AC ratios of 0, 2, 5, 10, and 15 wt % to increase electrical conductivity and facilitate electron transfer. AC cathodes were then evaluated in both MFCs and electrochemical cells and compared to reactors with cathodes made with Pt. Maximum power densities of MFCs were increased by 9-16% with CB compared to the plain AC in the first week. The optimal CB:AC ratio was 10% based on both MFC polarization tests and three electrode electrochemical tests. The maximum power density of the 10% CB cathode was initially 1560 ± 40 mW/m2 and decreased by only 7% after 5 months of operation compared to a 61% decrease for the control (Pt catalyst, 570 ± 30 mW/m2 after 5 months). The catalytic activities of Pt and AC (plain or with 10% CB) were further examined in rotating disk electrode (RDE) tests that minimized mass transfer limitations. The RDE tests showed that the limiting current of the AC with 10% CB was improved by up to 21% primarily due to a decrease in charge transfer resistance (25%). These results show that blending CB in AC is a simple and effective strategy to enhance AC cathode performance in MFCs and that further improvement in performance could be obtained by reducing mass transfer limitations. © 2014 American Chemical Society.

  14. Design of Low Cost, Highly Adsorbent Activated Carbon Fibers for Air/Water Purification

    National Research Council Canada - National Science Library

    Mangun, Christian

    1999-01-01

    .... proposes a novel activated carbon fiber (ACF) that will combine the low cost and durability of GAC with tailored pore size and pore surface chemistry for improved defense against chemical weapons...

  15. Utilization of turkey manure as granular activated carbon: physical, chemical and adsorptive properties.

    Science.gov (United States)

    Lima, Isabel; Marshall, Wayne E

    2005-01-01

    The high availability of large quantities of turkey manure generated from turkey production makes it an attractive feedstock for carbon production. Pelletized samples of turkey litter and cake were converted to granular activated carbons (GACs) by steam activation. Water flow rate and activation time were changed to produce a range of activation conditions. The GACs were characterized for select physical (yield, surface area, bulk density, attrition), chemical (pH, surface charge) and adsorptive properties (copper ion uptake). Carbon physical and adsorptive properties were dependent on activation time and quantity of steam used as activant. Yields varied from 23% to 37%, surface area varied from 248 to 472 m(2)/g and copper ion adsorption varied from 0.72 to 1.86 mmol Cu(2+)/g carbon. Copper ion adsorption greatly exceeded the values for two commercial GACs. GACs from turkey litter and cake show considerable potential to remove metal ions from water.

  16. Comparison Between Dielectric Barrier Discharge Plasma and Ozone Regenerations of Activated Carbon Exhausted with Pentachlorophenol

    Science.gov (United States)

    Qu, Guangzhou; Liang, Dongli; Qu, Dong; Huang, Yimei; Li, Jie

    2014-06-01

    In this study, two regeneration methods (dielectric barrier discharge (DBD) plasma and ozone (O3) regeneration) of saturated granular activated carbon (GAC) with pentachlorophenol (PCP) were compared. The results show that the two regeneration methods can eliminate contaminants from GAC and recover its adsorption properties to some extent. Comparing the DBD plasma with O3 regeneration, the adsorption rate and the capacity of the GAC samples after DBD plasma regeneration are greater than those after O3 regeneration. O3 regeneration decreases the specific surface area of GAC and increases the acidic surface oxygen groups on the surface of GAC, which causes a decrease in PCP on GAC uptake. With increasing regeneration cycles, the regeneration efficiencies of the two methods decrease, but the decrease in the regeneration efficiencies of GAC after O3 regeneration is very obvious compared with that after DBD plasma regeneration. Furthermore, the equilibrium data were fitted by the Freundlich and Langmuir models using the non-linear regression technique, and all the adsorption equilibrium isotherms fit the Langmuir model fairly well, which demonstrates that the DBD plasma and ozone regeneration processes do not appear to modify the adsorption process, but to shift the equilibrium towards lower adsorption concentrations. Analyses of the weight loss of GAC show that O3 regeneration has a lower weight loss than DBD plasma regeneration.

  17. Preparation of iron-impregnated granular activated carbon for arsenic removal from drinking water.

    Science.gov (United States)

    Chang, Qigang; Lin, Wei; Ying, Wei-chi

    2010-12-15

    Granular activated carbon (GAC) was impregnated with iron through a new multi-step procedure using ferrous chloride as the precursor for removing arsenic from drinking water. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis demonstrated that the impregnated iron was distributed evenly on the internal surface of the GAC. Impregnated iron formed nano-size particles, and existed in both crystalline (akaganeite) and amorphous iron forms. Iron-impregnated GACs (Fe-GACs) were treated with sodium hydroxide to stabilize iron in GAC and impregnated iron was found very stable at the common pH range in water treatments. Synthetic arsenate-contaminated drinking water was used in isotherm tests to evaluate arsenic adsorption capacities and iron use efficiencies of Fe-GACs with iron contents ranging from 1.64% to 12.13% (by weight). Nonlinear regression was used to obtain unbiased estimates of Langmuir model parameters. The arsenic adsorption capacity of Fe-GAC increased significantly with impregnated iron up to 4.22% and then decreased with more impregnated iron. Fe-GACs synthesized in this study exhibited higher affinity for arsenate as compared with references in literature and shows great potential for real implementations. Copyright © 2010 Elsevier B.V. All rights reserved.

  18. Redox-controlled carbon and phosphorus burial: A mechanism for enhanced organic carbon sequestration during the PETM

    Science.gov (United States)

    Komar, Nemanja; Zeebe, Richard E.

    2017-12-01

    Geological records reveal a major perturbation in carbon cycling during the Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma), marked by global warming of more than 5 °C and a prominent negative carbon isotope excursion of at least 2.5‰ within the marine realm. The entire event lasted about 200,000 yr and was associated with a massive release of light carbon into the ocean-atmosphere system over several thousands of years. Here we focus on the terminal stage of the PETM, during which the ocean-atmosphere system rapidly recovered from the carbon cycle perturbation. We employ a carbon-cycle box model to examine the feedbacks between surface ocean biological production, carbon, oxygen, phosphorus, and carbonate chemistry during massive CO2 release events, such as the PETM. The model results indicate that the redox-controlled carbon-phosphorus feedback is capable of producing enhanced organic carbon sequestration during large carbon emission events. The locale of carbon oxidation (ocean vs. atmosphere) does not affect the amount of carbon sequestered. However, even though the model produces trends consistent with oxygen, excess accumulation rates of organic carbon (∼1700 Pg C during the recovery stage), export production and δ13 C data, it fails to reproduce the magnitude of change of sediment carbonate content and the CCD over-deepening during the recovery stage. The CCD and sediment carbonate content overshoot during the recovery stage is muted by a predicted increase in CaCO3 rain. Nonetheless, there are indications that the CaCO3 export remained relatively constant during the PETM. If this was indeed true, then an initial pulse of 3,000 Pg C followed by an additional, slow leak of 2,500 Pg C could have triggered an accelerated nutrient supply to the surface ocean instigating enhanced organic carbon export, consequently increasing organic carbon sequestration, resulting in an accelerated restoration of ocean-atmosphere biogeochemistry during the termination

  19. Adsorption of selected emerging contaminants onto PAC and GAC: Equilibrium isotherms, kinetics, and effect of the water matrix.

    Science.gov (United States)

    Real, Francisco J; Benitez, F Javier; Acero, Juan L; Casas, Francisco

    2017-07-03

    The removal of three emerging contaminants (ECs) (amitriptyline hydrochloride (AH), methyl salicylate (MS) and 2-phenoxyethanol (PE)) dissolved in several water matrices by means of their adsorption onto powdered activated carbon (PAC) and granular activated carbon (GAC) has been investigated. When dissolved in ultrapure water, adsorption of the ECs followed the trend of AH > MS > PE, with a positive effect of the adsorbent dose. According to the analysis of the adsorption isotherms and adsorption kinetics, PAC showed strongly higher adsorption efficiency in both capacity and velocity of the adsorption, in agreement with its higher mesoporosity. Equilibrium isotherm data were fitted by Langmuir and Freundlich models. Pseudo-second order kinetics modeled very successfully the adsorption process. Finally, the effect of the presence of dissolved organic matter (DOM) in the water matrices (ultrapure water, surface water and two effluents from wastewater treatment plants) on the adsorption of the selected ECs onto PAC was established, as well as its performance on the removal of water quality parameters. Results show a negative effect of the DOM content on the adsorption efficiency. Over 50% of organic matter was removed with high PAC doses, revealing that adsorption onto PAC is an effective technology to remove both micro-pollutants and DOM from water matrices.

  20. Comparison of toluene adsorption among granular activated carbon and different types of activated carbon fibers (ACFs).

    Science.gov (United States)

    Balanay, Jo Anne G; Crawford, Shaun A; Lungu, Claudiu T

    2011-10-01

    Activated carbon fiber (ACF) has been demonstrated to be a good adsorbent for the removal of organic vapors in air. Some ACF has a comparable or larger surface area and higher adsorption capacity when compared with granular activated carbon (GAC) commonly used in respiratory protection devices. ACF is an attractive alternative adsorbent to GAC because of its ease of handling, light weight, and decreasing cost. ACF may offer the potential for short-term respiratory protection for first responders and emergency personnel. This study compares the critical bed depths and adsorption capacities for toluene among GAC and ACF of different forms and surface areas. GAC and ACF in cloth (ACFC) and felt (ACFF) forms were challenged in stainless steel chambers with a constant concentration of 500 ppm toluene via conditioned air at 25°C, 50% RH, and constant airflow (7 L/min). Breakthrough data were obtained for each adsorbent using gas chromatography with flame ionization detector. Surface areas of each adsorbent were determined using a physisorption analyzer. Results showed that the critical bed depth of GAC is 275% higher than the average of ACFC but is 55% lower than the average of ACFF. Adsorption capacity of GAC (with a nominal surface area of 1800 m(2)/g) at 50% breakthrough is 25% higher than the average of ACF with surface area of 1000 m(2)/g, while the rest of ACF with surface area of 1500 m(2)/g and higher have 40% higher adsorption capacities than GAC. ACFC with higher surface area has the smallest critical bed depth and highest adsorption capacity, which makes it a good adsorbent for thinner and lighter respirators. We concluded that ACF has great potential for application in respiratory protection considering its higher adsorption capacity and lower critical bed depth in addition to its advantages over GAC, particularly for ACF with higher surface area.

  1. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)(2)CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell type full-cell are tested for their electrochemical performance between 700 and 800 degrees C. Performance...... was investigated using current-potential-power density curves. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4) and dopedceria (CeO2, Ce1-xGdxO2-x/2, Ce1-xRExO2-delta (RE = Pr, Sm)), the effectiveness...

  2. The Implications of Fe2O3 and TiO2 Nanoparticles on the Removal of Trichloroethylene by Activated Carbon in the Presence and Absence of Humic Acid

    Science.gov (United States)

    The implications of Fe2O3 and TiO2 nanoparticles (NPs) on a granular activated carbon (GAC) adsorber and their impact on the removal of Trichloroethylene (TCE) were investigated in the presence of humic acid (HA). The surface charge of the GAC and NPs was obtained in the presence...

  3. Application of multi-walled carbon nanotubes to enhance anodic ...

    African Journals Online (AJOL)

    The effect of multi-walled carbon nanotube (MWCNT) modification of anodes and the optimisation of relevant parameters thereof for application in an Enterobacter cloacae microbial fuel cell were examined. The H – type microbial fuel cells were used for the fundamental studies, with a carbon sheet as a control anode and ...

  4. Pilot absorption experiments with carbonic anhydrase enhanced MDEA

    DEFF Research Database (Denmark)

    Gladis, Arne; F. Lomholdt, Niels; Fosbøl, Philip Loldrup

    2017-01-01

    -methyl-diethanolamine (MDEA) solvent, with and without the enzyme carbonic anhydrase (CA). The absorption experiments were performed at atmospheric pressure and agas phase carbon dioxide mole fraction of 0.13. During experiments liquid samples were withdrawn at each meter of column height and the solvent loading...

  5. Catalytic Enhancement of Solid Carbon Oxidation in HDCFCs

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62-38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell (SOFC)-type full-cell (NiO-yttria-stablized zirconia (YSZ)|YSZ|lanthanum strontium manganite (LSM...... data as a function of temperature, anode and cathode atmospheres, and their flow rates are discussed. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, and Mn3O4, Fig. 1) and doped-ceria (CeO2, Ce1-xGdxO2, Ce1-x...... in the carbon-carbonate mixture in the anode chamber of an HDCFC. 96-4 vol% N2-CO2 (anode), air (cathode), 755°C, 0-600 mA, 50 mA/step. Power density corrected to cathode geometric surface area. [Formula]...

  6. Carbon Nanotube Electrode Arrays For Enhanced Chemical and Biological Sensing

    Science.gov (United States)

    Han, Jie

    2003-01-01

    Applications of carbon nanotubes for ultra-sensitive electrical sensing of chemical and biological species have been a major focus in NASA Ames Center for Nanotechnology. Great progress has been made toward controlled growth and chemical functionalization of vertically aligned carbon nanotube arrays and integration into micro-fabricated chip devices. Carbon nanotube electrode arrays devices have been used for sub-attomole detection of DNA molecules. Interdigitated carbon nanotubes arrays devices have been applied to sub ppb (part per billion) level chemical sensing for many molecules at room temperature. Stability and reliability have also been addressed in our device development. These results show order of magnitude improvement in device performance, size and power consumption as compared to micro devices, promising applications of carbon nanotube electrode arrays for clinical molecular diagnostics, personal medical testing and monitoring, and environmental monitoring.

  7. Effects of coconut granular activated carbon pretreatment on membrane filtration in a gravitational driven process to improve drinking water quality.

    Science.gov (United States)

    da Silva, Flávia Vieira; Yamaguchi, Natália Ueda; Lovato, Gilselaine Afonso; da Silva, Fernando Alves; Reis, Miria Hespanhol Miranda; de Amorim, Maria Teresa Pessoa Sousa; Tavares, Célia Regina Granhen; Bergamasco, Rosângela

    2012-01-01

    This study evaluates the performance of a polymeric microfiltration membrane, as well as its combination with a coconut granular activated carbon (GAC) pretreatment, in a gravitational filtration module, to improve the quality of water destined to human consumption. The proposed membrane and adsorbent were thoroughly characterized using instrumental techniques, such as contact angle, Brunauer-Emmett-Teller) and Fourier transform infrared spectroscopy analyses. The applied processes (membrane and GAC + membrane) were evaluated regarding permeate flux, fouling percentage, pH and removal of Escherichia coli, colour, turbidity and free chlorine. The obtained results for filtrations with and without GAC pretreatment were similar in terms of water quality. GAC pretreatment ensured higher chlorine removals, as well as higher initial permeate fluxes. This system, applying GAC as a pretreatment and a gravitational driven membrane filtration, could be considered as an alternative point-of-use treatment for water destined for human consumption.

  8. A Colorimetric Method for the Determination of the Exhaustion Level of Granular Activated Carbons Used in Rum Production

    Directory of Open Access Journals (Sweden)

    Harold Crespo Sariol

    2016-09-01

    Full Text Available Spectrophotometric measurement applied on saturated granular activated carbon (GAC is not yet explored. A colorimetric method in the visible range has been developed in order to determine the exhaustion level of GAC used in rum production. Aqueous ammonia solution has been used as an indicative agent to determine the extraction rate of taste compounds within the rum production process and the exhaustion degree of the GAC. The colorimetric results showed excellent correlation with the iodine number and the contact pH. The proposed colorimetric method opens possibilities for rum producers to improve the management and economical use of the activated carbon at the industrial scale.

  9. Carbon dioxide enhanced oil recovery performance according to the literature

    Science.gov (United States)

    Olea, Ricardo A.

    2017-07-17

    IntroductionThe need to increase the efficiency of oil recovery and environmental concerns are bringing to prominence the use of carbon dioxide (CO2) as a tertiary recovery agent. Assessment of the impact of flooding with CO2 all eligible reservoirs in the United States not yet undergoing enhanced oil recovery (EOR) requires making the best possible use of the experience gained in 40 years of applications. Review of the publicly available literature has located relevant CO2-EOR information for 53 units (fields, reservoirs, pilot areas) in the United States and 17 abroad.As the world simultaneously faces an increasing concentration of CO2 in the atmosphere and a higher demand for fossil fuels, the CO2-EOR process continues to gain popularity for its efficiency as a tertiary recovery agent and for the potential for having some CO2 trapped in the subsurface as an unintended consequence of the enhanced production (Advanced Resources International and Melzer Consulting, 2009). More extensive application of CO2-EOR worldwide, however, is not making it significantly easier to predict the exact outcome of the CO2 flooding in new reservoirs. The standard approach to examine and manage risks is to analyze the intended target by conducting laboratory work, running simulation models, and, finally, gaining field experience with a pilot test. This approach, though, is not always possible. For example, assessment of the potential of CO2-EOR at the national level in a vast country such as the United States requires making forecasts based on information already available.Although many studies are proprietary, the published literature has provided reviews of CO2-EOR projects. Yet, there is always interest in updating reports and analyzing the information under new perspectives. Brock and Bryan (1989) described results obtained during the earlier days of CO2-EOR from 1972 to 1987. Most of the recovery predictions, however, were based on intended injections of 30 percent the size of

  10. The absorption of gases in aqueous activated carbon slurries enhanced by adsorbing or catalytic particles

    NARCIS (Netherlands)

    Holstvoogd, R.D.; van Swaaij, Willibrordus Petrus Maria; van Dierendonck, L.L.

    1988-01-01

    The enhanced absorption of gases in aqueous activated carbon slurries of fine particles is studied with an instationary absorption model taking into account the finite adsorption capacity of the carbon particles, and with a stationary geometrical model, which describes the absorption into a highly

  11. The influence of adsorption capacity on enhanced gas absorption in activated carbon slurries

    NARCIS (Netherlands)

    Holstvoogd, R.D.; van Swaaij, Willibrordus Petrus Maria

    1990-01-01

    The enhanced absorption of gases in aqueous activated carbbon slurries of fine particles is studied with a non-steady-state absorption model, taking into account the finite adsorption capacity of the carbon particles. It has been found that, for the different gas/activated carbon slurry systems

  12. Thermohaline mixing and gravitational settling in carbon-enhanced metal-poor stars

    NARCIS (Netherlands)

    Stancliffe, R.J.; Glebbeek, E.|info:eu-repo/dai/nl/30483324X

    2008-01-01

    We investigate the formation of carbon-enhanced metal-poor (CEMP) stars via the scenario of mass transfer from a carbon-rich asymptotic giant branch primary to a low-mass companion in a binary system. We explore the extent to which material accreted from a companion star mixes with that of the

  13. Indirect involvement of armorphous carbon layer on convective heat transfer enhancement using carbon nanofibers

    NARCIS (Netherlands)

    Taha, T.J.; Lefferts, Leonardus; van der Meer, Theodorus H.

    2015-01-01

    In this work, an experimental heat transfer investigation was carried out to investigate the combined influence of both amorphous carbon (a-C) layer thickness and carbon nanofibers (CNFs) on the convective heat transfer behavior. Synthesis of these carbon nanostructures was achieved using catalytic

  14. Characteristic numbers of granular activated carbon for the elimination of micropollutants from effluents of municipal wastewater treatment plants.

    Science.gov (United States)

    Benstoem, F; Pinnekamp, J

    2017-07-01

    Adsorption on granular activated carbon (GAC) is a promising step to extend existing treatment trains in municipal wastewater treatment plants (WWTPs) and, thus, to reduce the concentration of micropollutants (MPs) (e.g. pharmaceuticals) in wastewater. It is common practice to use characteristic numbers when choosing GAC for a specific application. In this study, characteristic numbers were correlated for five different GACs, with measured adsorption capacities of these carbons for three pharmaceutical MPs (carbamazepine, diclofenac and sulfamethoxazole) and dissolved organic carbon of a WWTP effluent. The adsorption capacities were measured using rapid small scale column tests. Density of GAC showed the highest correlation to adsorption of MP. All other characteristic numbers (iodine number, Brunauer-Emmett-Teller (BET) surface and methylene blue titre) are not suitable markers for choosing an appropriate activated carbon product for the elimination of MPs from municipal wastewater.

  15. Studies to Enhance Superconductivity in Thin Film Carbon

    Science.gov (United States)

    Pierce, Benjamin; Brunke, Lyle; Burke, Jack; Vier, David; Steckl, Andrew; Haugan, Timothy

    2012-02-01

    With research in the area of superconductivity growing, it is no surprise that new efforts are being made to induce superconductivity or increase transition temperatures (Tc) in carbon given its many allotropic forms. Promising results have been published for boron doping in diamond films, and phosphorus doping in highly oriented pyrolytic graphite (HOPG) films show hints of superconductivity.. Following these examples in the literature, we have begun studies to explore superconductivity in thin film carbon samples doped with different elements. Carbon thin films are prepared by pulsed laser deposition (PLD) on amorphous SiO2/Si and single-crystal substrates. Doping is achieved by depositing from (C1-xMx) single-targets with M = B4C and BN, and also by ion implantation into pure-carbon films. Previous research had indicated that Boron in HOPG did not elicit superconducting properties, but we aim to explore that also in thin film carbon and see if there needs to be a higher doping in the sample if trends were able to be seen in diamond films. Higher onset temperatures, Tc , and current densities, Jc, are hoped to be achieved with doping of the thin film carbon with different elements.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Tseh-Jen; Colvin, Neil; Kondratenko, Serguei [Axcelis Technologies, Inc. 108 Cherry Hill Drive, Beverly, MA 01915 (United States)

    2012-11-06

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

  17. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Supply of carbon dioxide for enhanced oil recovery. Final report, October 15, 1976--September 1, 1977

    Energy Technology Data Exchange (ETDEWEB)

    Rump, W.M.; Hare, M.; Porter, R.E.

    1977-09-01

    Results are presented from a study of the carbon dioxide supply situation for miscible flooding operations to enhance oil recovery. Candidate oil reservoirs were identified, and the carbon dioxide requirements and the potential recoverable oil for some of these were estimated. A survey of carbon dioxide sources has been conducted within the geographic areas where candidate oil reservoirs exist. Sources considered were both high and low quality gases from combustion vents, chemical process stacks, and naturally occurring gas deposits. The survey shows more than enough carbon dioxide is available from above-ground sources alone to meet expected demands. Systems to purify and deliver the carbon dioxide were designed and the costs of the delivered carbon dioxide estimated. Lowest cost is carbon dioxide from natural source with credit for by-product methane. A more comprehensive survey of above-ground and natural sources is recommended.

  19. Graphene-analogue carbon nitride: novel exfoliation synthesis and its application in photocatalysis and photoelectrochemical selective detection of trace amount of Cu2+

    Science.gov (United States)

    Xu, Hui; Yan, Jia; She, Xiaojie; Xu, Li; Xia, Jiexiang; Xu, Yuanguo; Song, Yanhua; Huang, Liying; Li, Huaming

    2014-01-01

    Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene-analogue carbon nitride had a new features that could make it suitable as a sensor for Cu2+ determination. So GA-C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu2+ were also discussed.Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C3N4) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C3N4-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene

  20. Characterizing Adsorption Performance of Granular Activated Carbon with Permittivity.

    Science.gov (United States)

    Yang, Yang; Shi, Chao; Zhang, Yi; Ye, Jinghua; Zhu, Huacheng; Huang, Kama

    2017-03-07

    A number of studies have achieved the consensus that microwave thermal technology can regenerate the granular activated carbon (GAC) more efficiently and energy-conservatively than other technologies. In particular, in the microwave heating industry, permittivity is a crucial parameter. This paper developed two equivalent models to establish the relationship between effective complex permittivity and pore volume of the GAC. It is generally based on Maxwell-Garnett approximation (MGA) theory. With two different assumptions in the model, two quantificational expressions were derived, respectively. Permittivity measurements and Brunauer-Emmett-Teller (BET) testing had been introduced in the experiments. Results confirmed the two expressions, which were extremely similar. Theoretical and experimental graphs were matched. This paper set up a bridge which links effective complex permittivity and pore volume of the GAC. Furthermore, it provides a potential and convenient method for the rapid assisted characterization of the GAC in its adsorption performance.

  1. Effects of four different drying methods on the carotenoid composition and antioxidant capacity of dried Gac peel.

    Science.gov (United States)

    Chuyen, Hoang V; Roach, Paul D; Golding, John B; Parks, Sophie E; Nguyen, Minh H

    2017-03-01

    Gac fruit (Momordica cochinchinensis Spreng.) is a rich source of carotenoids for the manufacture of powder, oil and capsules for food, cosmetic and pharmaceutical uses. Currently, only the aril of the Gac fruit is processed and the peel, similar to the other components, is discarded, although it contains high level of carotenoids, which could be extracted for commercial use. In the present study, four different drying methods (hot-air, vacuum, heat pump and freeze drying), different temperatures and drying times were investigated for producing dried Gac peel suitable for carotenoid extraction. The drying methods and drying temperatures significantly affected the drying time, carotenoid content and antioxidant capacity of the dried Gac peel. Among the investigated drying methods, hot-air drying at 80  o C and vacuum drying at 50  o C produced dried Gac peel that exhibited the highest retention of carotenoids and the strongest antioxidant capacity. Hot-air drying at 80  o C and vacuum drying at 50  o C are recommended for the drying of Gac peel. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  2. Skeletal myotube formation enhanced by electrospun polyurethane carbon nanotube scaffolds

    Science.gov (United States)

    Sirivisoot, Sirinrath; Harrison, Benjamin S

    2011-01-01

    Background This study examined the effects of electrically conductive materials made from electrospun single- or multiwalled carbon nanotubes with polyurethane to promote myoblast differentiation into myotubes in the presence and absence of electrical stimulation. Methods and results After electrical stimulation, the number of multinucleated myotubes on the electrospun polyurethane carbon nanotube scaffolds was significantly larger than that on nonconductive electrospun polyurethane scaffolds (5% and 10% w/v polyurethane). In the absence of electrical stimulation, myoblasts also differentiated on the electrospun polyurethane carbon nanotube scaffolds, as evidenced by expression of Myf-5 and myosin heavy chains. The myotube number and length were significantly greater on the electrospun carbon nanotubes with 10% w/v polyurethane than on those with 5% w/v polyurethane. The results suggest that, in the absence of electrical stimulation, skeletal myotube formation is dependent on the morphology of the electrospun scaffolds, while with electrical stimulation it is dependent on the electrical conductivity of the scaffolds. Conclusion This study indicates that electrospun polyurethane carbon nanotubes can be used to modulate skeletal myotube formation with or without application of electrical stimulation. PMID:22072883

  3. Carbon nanotubes enhanced the lead toxicity on the freshwater fish

    Science.gov (United States)

    Martinez, D. S. T.; Alves, O. L.; Barbieri, E.

    2013-04-01

    Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO3-MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO3-treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ζ-potential and Raman spectroscopy]. HNO3-MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO3-MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications.

  4. High Interlaminar Shear Strength Enhancement of Carbon Fiber/Epoxy Composite through Fiber- and Matrix-Anchored Carbon Nanotube Networks.

    Science.gov (United States)

    Wang, Yilei; Raman Pillai, Suresh Kumar; Che, Jianfei; Chan-Park, Mary B

    2017-03-15

    To improve the interlaminar shear strength (ILSS) of carbon fiber reinforced epoxy composite, networks of multiwalled carbon nanotubes (MWNTs) were grown on micron-sized carbon fibers and single-walled carbon nanotubes (SWNTs) were dispersed into the epoxy matrix so that these two types of carbon nanotubes entangle at the carbon fiber (CF)/epoxy matrix interface. The MWNTs on the CF fiber (CF-MWNTs) were grown by chemical vapor deposition (CVD), while the single-walled carbon nanotubes (SWNTs) were finely dispersed in the epoxy matrix precursor with the aid of a dispersing agent polyimide-graft-bisphenol A diglyceryl acrylate (PI-BDA) copolymer. Using vacuum assisted resin transfer molding, the SWNT-laden epoxy matrix precursor was forced into intimate contact with the "hairy" surface of the CF-MWNT fiber. The tube density and the average tube length of the MWNT layer on CF was controlled by the CVD growth time. The ILSS of the CF-MWNT/epoxy resin composite was examined using the short beam shear test. With addition of MWNTs onto the CF surface as well as SWNTs into the epoxy matrix, the ILSS of CF/epoxy resin composite was 47.59 ± 2.26 MPa, which represented a ∼103% increase compared with the composite made with pristine CF and pristine epoxy matrix (without any SWNT filler). FESEM established that the enhanced composite did not fail at the CF/epoxy matrix interface.

  5. Enhancement of semiconducting single-wall carbon nanotubes photoluminescence

    OpenAIRE

    Gaufrès, Etienne; Izard, Nicolas; Vivien, Laurent; Kazaoui, Saïd; Marris-Morini, Delphine; Cassan, Eric

    2009-01-01

    International audience; Photoluminescence properties of semiconducting single wall carbon nanotubes (s-SWNT) thin films with different metallic single wall carbon nanotubes (m-SWNT) concentrations are reported. s-SWNT purified samples are obtained by polymer assisted selective extraction. We show that a few m-SWNT in the sample generates a drastic quenching of the emission. Therefore, highly purified s-SWNT films are a strongly luminescent material and a good candidate for future applications in p...

  6. Nitrite sensing based on the carbon dots-enhanced chemiluminescence from peroxynitrous acid and carbonate.

    Science.gov (United States)

    Lin, Zhen; Dou, Xiangnan; Li, Haifang; Ma, Yuan; Lin, Jin-Ming

    2015-01-01

    In this work, chemiluminescence (CL) from peroxynitrous acid (ONOOH)-carbonate system greatly amplified by carbon dots was observed. The CL mechanism of the ONOOH-carbonate-carbon dots system has been investigated and the results reveal that the carbon dots could serve as the energy acceptor, which gives us new insight into the optical properties of the new emerging carbon nanomaterial. There is a good linear relationship between the CL signal and the concentration of the nitrite using for ONOOH formation, which provides us a nitrite sensing method with sensitivity as high as 5.0×10(-9) M (S/N=3). The method has been successfully applied to the determination of nitrite in tap water with the recovery of 98%. The standard deviations are within 2.5%. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. THE ENHANCEMENT OF THE PHYSICAL ABSORPTION OF GASES IN AQUEOUS ACTIVATED CARBON SLURRIES

    NARCIS (Netherlands)

    TINGE, JT; DRINKENBURG, AAH

    The enhancement of the gas-liquid mass transfer rates in aqueous slurries containing small activated carbon particles was studied in a semi-batchwise operated stirred cell absorber with a plane interface. The maximum observed enhancement factors for absorption of propane, ethene and hydrogen in the

  8. Enhanced photoluminescence and characterization of multicolor carbon dots using plant soot as a carbon source.

    Science.gov (United States)

    Tan, Mingqian; Zhang, Lingxin; Tang, Rong; Song, Xiaojie; Li, Yimin; Wu, Hao; Wang, Yanfang; Lv, Guojun; Liu, Wanfa; Ma, Xiaojun

    2013-10-15

    Carbon dots (C-dots) are a class of novel fluorescent nanomaterials, which have drawn great attention for their potential applications in bio-nanotechnology. Multicolor C-dots have been synthesized by chemical nitric acid oxidation using the reproducible plant soot as raw material. TEM analysis reveals that the prepared C-dots have an average size of 3.1 nm. The C-dots are well dispersed in aqueous solution and are strongly fluorescent under the irradiation of ultra-violet light. X-ray photoelectron spectroscopy characterization demonstrates that the O/C atomic ratio for C-dots change to from 0.207 to 0.436 due to the chemical oxidation process. The photo bleaching experiment reveals that the C-dots show excellent photostability as compared with the conventional organic dyes, fluorescein and rhodamine B. The fluorescence intensity of the C-dots did not change significantly in the pH range of 3-10. To further enhance the fluorescence quantum yield, the C-dots were surface modified with four types of passivation ligands, 4,7,10-trioxa-1,13-tridecanediamine (TTDDA), poly-L-lysine (PLL), cysteine and chitosan and the fluorescence quantum yields of the TTDDA, PLL, cysteine and chitosan passivated C-dots were improved 1.53-, 5.94-, 2.00- and 3.68-fold, respectively. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The bio-application of the C-dots as fluorescent bio-probes was evaluated in cell imaging and ex vivo fish imaging, which suggests that the C-dots may have potential applications in biolabeling and bioimaging. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Application of multi-walled carbon nanotubes to enhance anodic ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-12-15

    Dec 15, 2009 ... A 252.6% increase in power output of the fuel cell was observed at an anode modified with 10 mg MWCNTs/ml dispersed in ... Key words: Multi-walled carbon nanotubes, microbial fuel cell, Enterobacter cloacae, functionalise, anode. INTRODUCTION ..... performance of direct methanol fuel cells. J. Power ...

  10. Identification of promoters and enhancers induced by carbon nanotube exposure

    DEFF Research Database (Denmark)

    Bornholdt, Jette; Lilje, Berit; Saber, Anne Thoustrup

    Usage of carbon nanotubes (CNTs) is increasing in industry due to their mechanical and electrical properties. However, pulmonary exposure to CNTs induces, an asbestos-like toxicological response characterized by persistent inflammation, granuloma formation and fibrosis with low no-effect levels...

  11. Surface enhanced Raman spectroscopic substrate utilizing gold nanoparticles on carbon nanotubes

    Science.gov (United States)

    Basu, Srismrita; Maulik, Subhodip; Hou, Hsuan-Chao; Daniels-Race, Theda; Feldman, Martin

    2017-11-01

    This paper reports a new low cost technique for fabricating Surface Enhanced Raman Spectroscopy substrates. A Gold (Au) nano-metallic structure for surface enhancement is created by depositing Au nanoparticles on a Multi-wall Carbon Nanotube layer previously deposited on the etched Aluminum foil. A low cost, simple method is used to deposit the nanotubes. Huge enhancements have been observed in both in vitro and in vivo measurements.

  12. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  13. Catalytic Enhancement of Carbon Black and Coal-Fueled Hybrid Direct Carbon Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Ippolito, Davide; Kammer Hansen, Kent

    2015-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62–38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell type full-cell are tested for their electrochemical performance between 700 and 800°C. Performance......, Ce1-xREExO2-δ (REE = Pr, Sm)) and metal oxides (LiMn2O4, Ag2O). Materials showing the highest activity in carbon black (Mn2O3, CeO2, Ce0.6Pr0.4O2-δ, Ag2O) were subsequently tested for catalytic activity toward bituminous coal, as revealed by both I-V-P curves and electrochemical impedance...... was investigated using current-voltage-power density curves. In the anode chamber, catalysts are mixed with the carbon-carbonate mixture. These catalysts include various manganese oxides (MnO2, Mn2O3, Mn3O4, MnO), metal carbonates (Ag2CO3, MnCO3, Ce2(CO3)3), metals (Ag, Ce, Ni), doped-ceria (CeO2, Ce1-xGdxO2-x/2...

  14. Effect of pre-acclimation of granular activated carbon on microbial electrolysis cell startup and performance

    KAUST Repository

    LaBarge, Nicole

    2016-09-09

    Microbial electrolysis cells (MECs) can generate methane by fixing carbon dioxide without using expensive catalysts, but the impact of acclimation procedures on subsequent performance has not been investigated. Granular activated carbon (GAC) was used to pre-enrich electrotrophic methanogenic communities, as GAC has been shown to stimulate direct transfer of electrons between different microbial species. MEC startup times using pre-acclimated GAC were improved compared to controls (without pre-acclimation or without GAC), and after three fed batch cycles methane generation rates were similar (P > 0.4) for GAC acclimated to hydrogen (22 ± 9.3 nmol cm− 3 d− 1), methanol (25 ± 9.7 nmol cm− 3 d− 1), and a volatile fatty acid (VFA) mix (22 ± 11 nmol cm− 3 d− 1). However, MECs started with GAC but no pre-acclimation had lower methane generation rates (13 ± 4.1 nmol cm− 3 d− 1), and MECs without GAC had the lowest rates (0.7 ± 0.8 nmol cm− 3 d− 1 after cycle 2). Microbes previously found in methanogenic MECs, or previously shown to be capable of exocellular electron transfer, were enriched on the GAC. Pre-acclimation using GAC is therefore a simple approach to enrich electroactive communities, improve methane generation rates, and decrease startup times in MECs. © 2016 Elsevier B.V.

  15. Enhancement of the in-plane shear properties of carbon fiber composites containing carbon nanotube mats

    Science.gov (United States)

    Kim, Hansang

    2015-01-01

    The in-plane shear property of carbon fiber laminates is one of the most important structural features of aerospace and marine structures. Fiber-matrix debonding caused by in-plane shear loading is the major failure mode of carbon fiber composites because of the stress concentration at the interfaces. In this study, carbon nanotube mats (CNT mat) were incorporated in two different types of carbon fiber composites. For the case of woven fabric composites, mechanical interlocking between the CNTs and the carbon fibers increased resistance to shear failure. However, not much improvement was observed for the prepreg composites as a result of incorporation of the CNT mats. The reinforcement mechanism of the CNT mat layer was investigated by a fractographic study using scanning electron microscopy. In addition, the CNT mat was functionalized by three different methods and the effectiveness of the functionalization methods was determined and the most appropriate functionalization method for the CNT mat was air oxidation.

  16. Surface modification of activated carbon for enhanced adsorption of perfluoroalkyl acids from aqueous solutions.

    Science.gov (United States)

    Zhi, Yue; Liu, Jinxia

    2016-02-01

    The objective of the research was to examine the effect of increasing carbon surface basicity on uptake of perfluorooctane sulfonic (PFOS) and carboxylic acids (PFOA) by activated carbon. Granular activated carbons made from coal, coconut shell, wood, and phenolic-polymer-based activated carbon fibers were modified through high-temperature and ammonia gas treatments to facilitate systematical evaluation of the impact of basicity of different origins. Comparison of adsorption isotherms and adsorption distribution coefficients showed that the ammonia gas treatment was more effective than the high-temperature treatment in enhancing surface basicity. The resultant higher point of zero charges and total basicity (measured by total HCl uptake) correlated with improved adsorption affinity for PFOS and PFOA. The effectiveness of surface modification to enhance adsorption varied with carbon raw material. Wood-based carbons and activated carbon fibers showed enhancement by one to three orders of magnitudes while other materials could experience reduction in adsorption towards either PFOS or PFOA. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Carbon Nanotube Chopped Fiber for Enhanced Properties in Additive Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Menchhofer, Paul A [ORNL; Lindahl, John M [ORNL; JohnsonPhD, DR Joseph E. [Nanocomp Technologies, Inc.

    2016-06-06

    Nanocomp Technologies, Inc. is working with Oak Ridge National Laboratory to develop carbon nanotube (CNT) composite materials and evaluate their use in additive manufacturing (3D printing). The first phase demonstrated feasibility and improvements for carbon nanotube (CNT)- acrylonitrile butadiene styrene (ABS) composite filaments use in additive manufacturing, with potential future work centering on further improvements. By focusing the initial phase on standard processing methods (developed mainly for the incorporation of carbon fibers in ABS) and characterization techniques, a basis of knowledge for the incorporation of CNTs in ABS was learned. The ability to understand the various processing variables is critical to the successful development of these composites. From the degradation effects on ABS (caused by excessive temperatures), to the length of time the ABS is in the melt state, to the order of addition of constituents, and also to the many possible mixing approaches, a workable flow sequence that addresses each processing step is critical to the final material properties. Although this initial phase could not deal with each of these variables in-depth, a future study is recommended that will build on the lessons learned for this effort.

  18. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    Science.gov (United States)

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  19. Enhanced performance in electrochemical energy storage and conversion via carbon-integrated nanostructures

    Science.gov (United States)

    Sheehan, Margaret K.

    Electrochemical energy storage and conversion applications benefit from the integration of nanostructures into the devices, as they have many more active sites per gram which enables excellent mass utilization of the active species. By controlling the surface of fuel cell catalysts, higher activity and efficiency can be achieved as compared to the bulk counterpart, with multiple catalyst facets of varying activity and efficiency. Nanostructured electrochemical capacitors have enhanced electrolyte diffusion over the surface of the electrode, facilitating high rate capability. Nanostructured materials for energy storage and conversion devices, such as electrochemical capacitors and proton exchange membrane fuel cells, can perform even better with the incorporation of carbon. High surface area carbon can enhance the activity of electrochemical capacitors by improving the conductivity of the electrode and/or enhancing the double layer capacitance. Carbon supports for fuel cell catalysts enable proper dispersion of active material without sacrificing conductivity. The work reported in this thesis is aimed toward improving the performance of electrochemical energy storage and conversion devices through novel incorporation of carbon. Carbon was first used to enhance the performance of electrocatalysts. By wrapping fuel cell catalysts in a porous carbon shell, the activity was increased over its bare and CNT-supported counterparts. The carbon shell synthetic method reported here is a good route to the production of a conductive host for Pd electrocatalysts with good contact and in one step with the formation of the Pd nanoparticles. Carbon was also used to enhance the performance of pseudocapacitors, first by incorporating it into the precursor spray solution in the generation of mesoporous metal oxides and then as a metal-organic framework-derived carbon host with dispersed electrochemically active metal oxides. A carbon network was generated from the pyrolysis of pore

  20. Iron and carbon monoxide enhance coagulation and attenuate fibrinolysis by different mechanisms.

    Science.gov (United States)

    Nielsen, Vance G; Pretorius, Etheresia

    2014-10-01

    Two parallel lines of investigation elucidating novel mechanisms by which iron (scanning electron microscopy-based) and carbon monoxide (viscoelastic-based) enhance coagulation and diminish fibrinolysis have emerged over the past few years. However, a multimodal approach to ascertain the effects of iron and carbon monoxide remained to be performed. Such investigation could be important, as iron and carbon monoxide are two of the products of heme catabolism via heme oxygenase-1, an enzyme upregulated in a variety of disease states associated with thrombophilia. Human plasma was exposed to ferric chloride, carbon monoxide derived from carbon monoxide-releasing molecule-2, or their combination. Viscoelastic studies demonstrated ferric chloride and carbon monoxide mediated enhancement of velocity of growth, and final clot strength, with the combination of the two molecules noted to have all the prothrombotic kinetic effects of either separately. Parallel ultrastructural studies demonstrated separate types of fibrin polymer cross-linking and matting in plasma exposed to ferric chloride and carbon monoxide, with the combination sharing features of each molecule. In conclusion, we present the first evidence that iron and carbon monoxide interact with key coagulation and fibrinolytic processes, resulting in thrombi that begin to form more quickly, grow faster, become stronger, and are more resistant to lysis.

  1. Performance evaluation of granular activated carbon system at Pantex: Rapid small-scale column tests to simulate removal of high explosives from contaminated groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Henke, J.L.; Speitel, G.E. [Univ. of Texas, Austin, TX (United States). Dept. of Civil Engineering

    1998-08-01

    A granular activated carbon (GAC) system is now in operation at Pantex to treat groundwater from the perched aquifer that is contaminated with high explosives. The main chemicals of concern are RDX and HMX. The system consists of two GAC columns in series. Each column is charged with 10,000 pounds of Northwestern LB-830 GAC. At the design flow rate of 325 gpm, the hydraulic loading is 6.47 gpm/ft{sup 2}, and the empty bed contact time is 8.2 minutes per column. Currently, the system is operating at less than 10% of its design flow rate, although flow rate increases are expected in the relatively near future. This study had several objectives: Estimate the service life of the GAC now in use at Pantex; Screen several GACs to provide a recommendation on the best GAC for use at Pantex when the current GAC is exhausted and is replaced; Determine the extent to which natural organic matter in the Pantex groundwater fouls GAC adsorption sites, thereby decreasing the adsorption capacity for high explosives; and Determine if computer simulation models could match the experimental results, thereby providing another tool to follow system performance.

  2. Unraveling the Mechanism for the Sharp-Tip Enhanced Electrocatalytic Carbon Dioxide Reduction: The Kinetics Decide.

    Science.gov (United States)

    Jiang, Huijun; Hou, Zhonghuai; Luo, Yi

    2017-12-04

    The electrocatalytic reduction reaction of carbon dioxide can be significantly enhanced by the use of a sharp-tip electrode. However, the experimentally observed rate enhancement is many orders of magnitudes smaller than what would be expected from an energetic point of view. The kinetics of this tip-enhanced reaction are shown to play a decisive role, and a novel reaction-diffusion kinetic model is proposed. The experimentally observed sharp-tip enhanced reaction and the maximal producing rate of carbon monoxide under different electrode potentials are well-reproduced. Moreover, the optimal performance shows a strong dependence on the interaction between CO2 and the local electric field, on the adsorption rate of CO2 , but not on the reaction barrier. Two new strategies to further enhance the reaction rate have also been proposed. The findings highlight the importance of kinetics in modeling electrocatalytic reactions. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. UV-activated persulfate oxidation and regeneration of NOM-Saturated granular activated carbon.

    Science.gov (United States)

    An, Dong; Westerhoff, Paul; Zheng, Mengxin; Wu, Mengyuan; Yang, Yu; Chiu, Chao-An

    2015-04-15

    A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 10(4) mJ/cm(2). The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. The ultrasonic-enhanced factor of mass-transfer coefficient in the supercritical carbon dioxide extraction

    Science.gov (United States)

    Luo, Benyi; Lu, Yigang

    2008-10-01

    Based on several hypotheses about the process of supercritical carbon dioxide extraction, the onflow around the solute granule is figured out by the Navier-Stocks equation. In combination with the Higbie’s solute infiltration model, the link between the mass-transfer coefficient and the velocity of flow is found. The mass-transfer coefficient with the ultrasonical effect is compared with that without the ultrasonical effect, and then a new parameter named the ultrasonic-enhanced factor of mass-transfer coefficient is brought forward, which describes the mathematical model of the supercritical carbon dioxide extraction process enhanced by ultrasonic. The model gives out the relationships among the ultrasonical power, the ultrasonical frequency, the radius of solute granule and the ultrasonic-enhanced factor of mass-transfer coefficient. The results calculated by this model fit well with the experimental data, including the extraction of Coix Lacryma-jobi Seed Oil (CLSO) and Coix Lacryma-jobi Seed Ester (CLSE) from coix seeds and the extraction of Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) from the alga by means of the ultrasonic-enhanced supercritical carbon dioxide extraction (USFE) and the supercritical carbon dioxide extraction (SFE) respectively. This proves the rationality of the ultrasonic-enhanced factor model. The model provides a theoretical basis for the application of ultrasonic-enhanced supercritical fluid extraction technique.

  5. Ferric oxide nanoparticles decorated carbon nanotubes and carbon nanofibers: From synthesis to enhanced removal of phenol

    OpenAIRE

    Asmaly, Hamza A.; Abussaud, Basim; Ihsanullah; Saleh, Tawfik A.; Gupta, Vinod Kumar; Atieh, Muataz Ali

    2015-01-01

    In this work, ferric oxide nanoparticle decorated carbon fibers and carbon nanotubes (CNF/Fe2O3 and CNT/Fe2O3) were synthesized and characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), zeta potential and BET surface area analyzer. The prepared nanocomposites were evaluated or the removal of phenol ions from aqueous solution. The effects of experimental...

  6. Enhanced top soil carbon stocks under organic farming

    Science.gov (United States)

    Gattinger, Andreas; Muller, Adrian; Haeni, Matthias; Skinner, Colin; Fliessbach, Andreas; Buchmann, Nina; Mäder, Paul; Stolze, Matthias; Smith, Pete; Scialabba, Nadia El-Hage; Niggli, Urs

    2012-01-01

    It has been suggested that conversion to organic farming contributes to soil carbon sequestration, but until now a comprehensive quantitative assessment has been lacking. Therefore, datasets from 74 studies from pairwise comparisons of organic vs. nonorganic farming systems were subjected to metaanalysis to identify differences in soil organic carbon (SOC). We found significant differences and higher values for organically farmed soils of 0.18 ± 0.06% points (mean ± 95% confidence interval) for SOC concentrations, 3.50 ± 1.08 Mg C ha−1 for stocks, and 0.45 ± 0.21 Mg C ha−1 y−1 for sequestration rates compared with nonorganic management. Metaregression did not deliver clear results on drivers, but differences in external C inputs and crop rotations seemed important. Restricting the analysis to zero net input organic systems and retaining only the datasets with highest data quality (measured soil bulk densities and external C and N inputs), the mean difference in SOC stocks between the farming systems was still significant (1.98 ± 1.50 Mg C ha−1), whereas the difference in sequestration rates became insignificant (0.07 ± 0.08 Mg C ha−1 y−1). Analyzing zero net input systems for all data without this quality requirement revealed significant, positive differences in SOC concentrations and stocks (0.13 ± 0.09% points and 2.16 ± 1.65 Mg C ha−1, respectively) and insignificant differences for sequestration rates (0.27 ± 0.37 Mg C ha−1 y−1). The data mainly cover top soil and temperate zones, whereas only few data from tropical regions and subsoil horizons exist. Summarizing, this study shows that organic farming has the potential to accumulate soil carbon. PMID:23071312

  7. Enhanced top soil carbon stocks under organic farming.

    Science.gov (United States)

    Gattinger, Andreas; Muller, Adrian; Haeni, Matthias; Skinner, Colin; Fliessbach, Andreas; Buchmann, Nina; Mäder, Paul; Stolze, Matthias; Smith, Pete; Scialabba, Nadia El-Hage; Niggli, Urs

    2012-10-30

    It has been suggested that conversion to organic farming contributes to soil carbon sequestration, but until now a comprehensive quantitative assessment has been lacking. Therefore, datasets from 74 studies from pairwise comparisons of organic vs. nonorganic farming systems were subjected to metaanalysis to identify differences in soil organic carbon (SOC). We found significant differences and higher values for organically farmed soils of 0.18 ± 0.06% points (mean ± 95% confidence interval) for SOC concentrations, 3.50 ± 1.08 Mg C ha(-1) for stocks, and 0.45 ± 0.21 Mg C ha(-1) y(-1) for sequestration rates compared with nonorganic management. Metaregression did not deliver clear results on drivers, but differences in external C inputs and crop rotations seemed important. Restricting the analysis to zero net input organic systems and retaining only the datasets with highest data quality (measured soil bulk densities and external C and N inputs), the mean difference in SOC stocks between the farming systems was still significant (1.98 ± 1.50 Mg C ha(-1)), whereas the difference in sequestration rates became insignificant (0.07 ± 0.08 Mg C ha(-1) y(-1)). Analyzing zero net input systems for all data without this quality requirement revealed significant, positive differences in SOC concentrations and stocks (0.13 ± 0.09% points and 2.16 ± 1.65 Mg C ha(-1), respectively) and insignificant differences for sequestration rates (0.27 ± 0.37 Mg C ha(-1) y(-1)). The data mainly cover top soil and temperate zones, whereas only few data from tropical regions and subsoil horizons exist. Summarizing, this study shows that organic farming has the potential to accumulate soil carbon.

  8. Enhanced electrochemical performance of carbon quantum dots-polyaniline hybrid

    Science.gov (United States)

    Zhao, Zhichao; Xie, Yibing

    2017-01-01

    Carbon quantum dots-polyaniline (CQDs-PANI) hybrid was developed as supercapacitor electorde material by incorporating CQDs into PANI. PANI nanowires were grown vertically on carbon fiber substrate to form an interconnected network structure. Meanwhile, CQDs were uniformly distributed in the interior and on the surface of well-established net-like PANI nanowires. High specific capacitance of 738.3 F g-1 at 1.0 A g-1 was obtained for CQDs-PANI compared to that of 432.5 F g-1 for pure PANI. The capacitance retention after 1000 cycles of CQDs-PANI and PANI is 78.0% and 68.0% at 5.0 A g-1, respectively. The high capacitance and reasonable cycle stability were ascribed to the incorporation of CQDs into PANI, which improved the conductivity and alleviated the volume change of the CQDs-PANI electrode during the charge/discharge process. In addition, a flexible solid-state CQDs-PANI supercapacitor was constructed using carbon paper as current collector and polyvinyl alcohol gel electrolyte, exhibiting the stable capacitive performance at planar and bending state. The specific capacitance, energy and power density were determined to be 169.2 mF cm-2, 33.8 μWh cm-2 and 0.3 mW cm-2 at a potential window of 1.2 V and a current density of 1.0 mA cm-2. CQDs-PANI presented the promising application in flexible energy-related device.

  9. Enhancing the stability of silicon nanosheets electrodes by fluoroethylene carbonate

    Science.gov (United States)

    Park, Jeong Min; Kim, Sujin; Ha, Jung Hoon; Kim, Sung Wook; Lee, Jaejun; Park, Sangwon; Cho, Byung-Won; Choi, Heon-Jin

    2017-09-01

    Stabilization of the SEI layer that is formed by consuming active lithium in electrolytes is a critical issue for improving the cyclability of lithium ion batteries. We used SiNSs as anodes and investigated the effect of fluoroethylene carbonate (FEC) additives on the SEI layer. Our XPS, EIS and TEM analysis of Csbnd O and Cdbnd O bonds, interfacial resistance and thickness of SEl layer, respectively, shows that the FEC produces electrochemically and mechanically stable SEI layer. The SiNSs with FEC showed the capacity of over 1500 mA h g-1 with 95% efficiency after 200 cycles.

  10. Cavity induced fluorescence enhancement of graphitic carbon nitride submicron flakes

    Science.gov (United States)

    Veluthandath, Aneesh Vincent; Reddy Bongu, Sudhakara; Ramaprabhu, Sundara; Ballabh Bisht, Prem

    2017-01-01

    Graphitic carbon nitride (g-C3N4), which is structurally analogous to graphene, shows excellent fluorescent yield. Sharp ripple structure is observed in the fluorescence spectra of g-C3N4 flakes grafted on the surface of single polymethyl methacrylate (PMMA) microspheres. The intensities and the number of modes of these structures nonlinearly vary with the size of micro-cavity and the coupled power. Theoretical simulations carried out with the help of Mie theory show that the ripple structure is due to modulation of the fluorescence by the whispering gallery modes (WGMs) of the spherical microcavity.

  11. Development of an Activated Carbon-Based Electrode for the Capture and Rapid Electrolytic Reductive Debromination of Methyl Bromide from Postharvest Fumigations.

    Science.gov (United States)

    Li, Yuanqing; Liu, Chong; Cui, Yi; Walse, Spencer S; Olver, Ryan; Zilberman, David; Mitch, William A

    2016-10-18

    Due to concerns surrounding its ozone depletion potential, there is a need for technologies to capture and destroy methyl bromide (CH 3 Br) emissions from postharvest fumigations applied to control agricultural pests. Previously, we described a system in which CH 3 Br fumes vented from fumigation chambers could be captured by granular activated carbon (GAC). The GAC was converted to a cathode by submergence in a high ionic strength solution and connection to the electrical grid, resulting in reductive debromination of the sorbed CH 3 Br. The GAC bed was drained and dried for reuse to capture and destroy CH 3 Br fumes from the next fumigation. However, the loose GAC particles and slow kinetics of this primitive electrode necessitated improvements. Here, we report the development of a cathode containing a thin layer of small GAC particles coating carbon cloth as a current distributor. Combining the high sorption potential of GAC for CH 3 Br with the conductivity of the carbon cloth current distributor, the cathode significantly lowered the total cell resistance and achieved 96% reductive debromination of CH 3 Br sorbed at 30% by weight to the GAC within 15 h at -1 V applied potential vs standard hydrogen electrode, a time scale and efficiency suitable for postharvest fumigations. The cathode exhibited stable performance over 50 CH 3 Br capture and destruction cycles. Initial cost estimates indicate that this technique could treat CH 3 Br fumes at ∼$5/kg, roughly one-third of the cost of current alternatives.

  12. Analysis of the vhoGAC and vhtGAC operons from Methanosarcina mazei strain Gö1, both encoding a membrane-bound hydrogenase and a cytochrome b.

    Science.gov (United States)

    Deppenmeier, U; Blaut, M; Lentes, S; Herzberg, C; Gottschalk, G

    1995-01-15

    DNA encompassing the structural genes of two membrane-bound hydrogenases from Methanosarcina mazei Gö1 was cloned and sequenced. The genes, arranged in the order vhoG and vhoA as well as vhtG and vhtA, were identified as those encoding the small and the large subunits of the NiFe hydrogenases [Deppenmeier, U., Blaut, M., Schmidt, B. & Gottschalk, G. (1992) Arch. Microbiol. 157, 505-511]. Northern-blot analysis revealed that the structural genes formed part of two operons, both containing one additional open reading frame (vhoC and vhtC) which codes for a cytochrome b. This conclusion was drawn from the homology of the deduced N-terminal amino acid sequences of vhoC and vhtC and the N-terminus of a 27-kDa cytochrome isolated from Ms. mazei C16. VhoC and VhtC contain four tentative hydrophobic segments which might span the cytoplasmic membrane. Hydropathy plots suggest that His23 and His50 are involved in heme coordination. The comparison of the sequencing data of vhoG and vhtG with the experimentally determined N-terminus of the small subunit indicate the presence of a 48-amino-acid leader peptide in front of the polypeptides. VhoA and VhtA contained the conserved sequence DPCXXC in the C-terminal region, which excludes the presence of a selenocysteine residue in these hydrogenases. Promoter sequences were found upstream of vhoG and vhtG, respectively. Downstream of vhoC, a putative terminator sequence was identified. Alignments of the deduced amino acid sequences of the gene clusters vhoGAC and vhtGAC showed 92-97% identity. Only the C-termini of VhoC and VhtC were not similar.

  13. Enhanced production of green tide algal biomass through additional carbon supply.

    Science.gov (United States)

    de Paula Silva, Pedro H; Paul, Nicholas A; de Nys, Rocky; Mata, Leonardo

    2013-01-01

    Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci) to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2) enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO3 (-)) as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO3 (-) affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7-9.9), and grew at similar rates up to pH 9, demonstrating HCO3 (-) utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%), Chaetomorpha linum (24%) and to a lesser extent for Cladophora patentiramea (11%), compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO3 (-).

  14. Hydrogen storage in nanostructured carbons by spillover: bridge-building enhancement.

    Science.gov (United States)

    Lachawiec, Anthony J; Qi, Gongshin; Yang, Ralph T

    2005-11-22

    The hydrogen storage capacity in nanostructured carbon materials can be increased by atomic hydrogen spillover from a supported catalyst. A simple and effective technique was developed to build carbon bridges that serve to improve contact between a spillover source and a secondary receptor. In this work, a supported catalyst (Pd-C) served as the source of hydrogen atoms via dissociation and primary spillover and AX-21 or single-walled carbon nanotubes (SWNTs) were secondary spillover receptors. By carbonizing a bridge-forming precursor in the presence of the components, the hydrogen adsorption amount was increased by a factor of 2.9 for the AX-21 receptor and 1.6 for the SWNT receptor at 298 K and 100 kPa. Similar results were obtained at 10 MPa, indicating that the enhancement factor is a weak function of pressure. The AX-21 receptor with carbon bridges had the highest absolute capacity of 1.8 wt % at 298 K and 10 MPa. Reversibility was demonstrated through desorption and readsorption at 298 K. The bridge-building process appears to be receptor specific, and optimization may yield even greater enhancement. Using this technique, enhancements in storage of up to 17-fold on other carbon-based materials have been observed and will be reported elsewhere shortly.

  15. Enhanced production of green tide algal biomass through additional carbon supply.

    Directory of Open Access Journals (Sweden)

    Pedro H de Paula Silva

    Full Text Available Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2 enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO3 (- as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO3 (- affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7-9.9, and grew at similar rates up to pH 9, demonstrating HCO3 (- utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%, Chaetomorpha linum (24% and to a lesser extent for Cladophora patentiramea (11%, compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO3 (-.

  16. Carbon Nanoparticle Enhance Photoacoustic Imaging and Therapy for Bone Tissue Engineering

    Science.gov (United States)

    Talukdar, Yahfi

    Healing critical sized bone defects has been a challenge that led to innovations in tissue engineering scaffolds and biomechanical stimulations that enhance tissue regeneration. Carbon nanocomposite scaffolds have gained interest due to their enhanced mechanical properties. However, these scaffolds are only osteoconductive and not osteoinductive. Stimulating regeneration of bone tissue, osteoinductivity, has therefore been a subject of intense research. We propose the use of carbon nanoparticle enhanced photoacoustic (PA) stimulation to promote and enhance tissue regeneration in bone tissue-engineering scaffolds. In this study we test the feasibility of using carbon nanoparticles and PA for in vivo tissue engineering applications. To this end, we investigate 1) the effect of carbon nanoparticles, such as graphene oxide nanoplatelets (GONP), graphene oxide nano ribbons (GONR) and graphene nano onions (GNO), in vitro on mesenchymal stem cells (MSC), which are crucial for bone regeneration; 2) the use of PA imaging to detect and monitor tissue engineering scaffolds in vivo; and 3) we demonstrate the potential of carbon nanoparticle enhanced PA stimulation to promote tissue regeneration and healing in an in vivo rat fracture model. The results from these studies demonstrate that carbon nanoparticles such as GNOP, GONR and GNO do not affect viability or differentiation of MSCs and could potentially be used in vivo for tissue engineering applications. Furthermore, PA imaging can be used to detect and longitudinally monitor subcutaneously implanted carbon nanotubes incorporated polymeric nanocomposites in vivo. Oxygen saturation data from PA imaging could also be used as an indicator for tissue regeneration within the scaffolds. Lastly, we demonstrate that daily stimulation with carbon nanoparticle enhanced PA increases bone fracture healing. Rats stimulated for 10 minutes daily for two weeks showed 3 times higher new cortical bone BV/TV and 1.8 times bone mineral density

  17. Dynamics of Intracellular Polymers in Enhanced Biological Phosphorus Removal Processes under Different Organic Carbon Concentrations

    Directory of Open Access Journals (Sweden)

    Lizhen Xing

    2013-01-01

    Full Text Available Enhanced biological phosphorus removal (EBPR may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

  18. Dynamics of intracellular polymers in enhanced biological phosphorus removal processes under different organic carbon concentrations.

    Science.gov (United States)

    Xing, Lizhen; Ren, Li; Tang, Bo; Wu, Guangxue; Guan, Yuntao

    2013-01-01

    Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs. A low influent organic carbon concentration induced a high production of extracellular carbohydrate. During both anaerobic and aerobic endogenous respirations, when glycogen decreased to around 80 ± 10 mg C per gram of volatile suspended solids, PAOs began to utilize polyphosphate significantly. Regressed by the first-order reaction model, glycogen possessed the highest degradation rate and then was followed by polyphosphate, while biomass decay had the lowest degradation rate.

  19. Enhanced carbon tolerance on Ni-based reforming catalyst with Ir alloying: A DFT study

    Science.gov (United States)

    Ahn, Kiyong; Choi, Sungjun; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Jedo; Kim, Hyoungchul

    2017-10-01

    Carbon deposition is a major cause of performance degradation for the Ni-based catalyst used in steam reforming of hydrocarbons. In this work, we perform first principle calculations to show that carbon tolerance behavior can be significantly enhanced by alloying Ni with Ir. The most stable atomic structure predicted by the surface phased diagram shows that Ir atoms prefer to stay on the surface of the alloy ensuring their exposure to the incoming gas. We find that the presence of Ir atoms suppress the surface migration of carbon atoms and weaken the stability of the adsorbed carbon agglomerates. Finally, we elucidate that the local reactivity change caused by the shift in the d-band structure is responsible for such good carbon tolerance behavior.

  20. Tuning the carbon nanotube photoluminescence enhancement at addition of cysteine through the change of external conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kurnosov, N.V.; Karachevtsev, M.V.; Leontiev, V.S.; Karachevtsev, V.A., E-mail: karachevtsev@ilt.kharkov.ua

    2017-01-15

    The enhancement of the photoluminescence (PL) from the semiconducting single-walled carbon nanotubes suspended with single-stranded DNA (ssDNA) in water observed after amino acids doping is the largest at cysteine addition. The PL intensity increased through the passivation of p-defects on the carbon nanotube sidewall by the cysteine molecules due to thiol group. The effect of several external factors on the cysteine-induced enhancement of PL from carbon nanotubes covered with ssDNA was studied: UV irradiation, tip or bath sonication treatment of the suspension, the ionic strength and pH of aqueous suspension. It turned out that all these factors have an essential influence on the dependence of the PL enhancement on the cysteine concentration through inducing of additional defects on nanotube as well as a change of the nanotube surface coverage with polymer. The obtained experimental results demonstrated that PL from carbon nanotubes can be exploited successfully for the monitoring of cysteine concentration in aqueous solution. - Highlights: • Cysteine doping enhances carbon nanotube emission more than other amino acids do. • SWNT emission dependence on cysteine concentration is tuned by UV irradiation and pH. • Type of sonication treatment influences SWNT PL dependence on cysteine concentration. • Polymer coverage and defectiveness of nanotubes effect on nanotube emission. • Graphic abstract.

  1. Carbon nanodots-based nanocomposites with enhanced photocatalytic performance and photothermal effects

    Science.gov (United States)

    Zhang, J.; Tang, Y. L.; Hu, G.; Gao, B. L.; Gan, Z. X.; Chu, P. K.

    2017-07-01

    Carbon nanomaterials with variable bandgaps exhibit wide spectral absorption, and photoluminescent nanodots have attracted much interest. In this work, carbon nanodots (CNDs) are grafted onto the surface of TiO2 nanotubes to enhance the photocatalytic properties. The CNDs increase light absorption, trap and shuttle photo-generated electrons, and enhance the pollutant adsorptivity. In addition, the synergistic photothermal effect of the CNDs-based nanocomposite facilitates photocatalysis. The CNDs-based nanocomposites with improved photothermal performance and efficient photocatalytic characteristics have large potential in environment and energy applications.

  2. Enhanced actuation in functionalized carbon nanotube–Nafion composites

    KAUST Repository

    Lian, Huiqin

    2011-08-01

    The fabrication and electromechanical performance of functionalized carbon nanotube (FCNT)-Nafion composite actuators were studied. The CNTs were modified successfully with polyethylene glycol (PEG), as verified by thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. Scanning electron microscopy (SEM) images show that the FCNTs are homogeneously dispersed in the Nafion matrix. The properties of FCNT-Nafion composites in terms of water uptake, ion exchange capacity, proton conductivity, dynamic mechanical properties, and actuation behavior were evaluated. The results show that the sample with 0.5 wt% FCNT exhibits the best overall behavior. Its storage modulus is 2.4 times higher than that of Nafion. In addition, the maximum generated strain and the blocking force for the same sample are 2 and 2.4 times higher compared to the neat Nafion actuator, respectively. © 2011 Elsevier B.V.

  3. Thermal conductive epoxy enhanced by nanodiamond-coated carbon nanotubes

    Science.gov (United States)

    Zhao, Bo; Jiang, Guohua

    2017-11-01

    Nanodiamond (ND) particles were coated on the surface of carbon nanotubes (CNTs) by chemical reactions. Reliable bonding was formed by the combination of acyl chloride on NDs and amine group on CNTs. ND coated CNTs (CNT-ND) were dispersed into epoxy to fabricate thermal conductive resins. The results show that the surface energy of CNTs is decreased by the coated NDs, which is contributed to the excellent dispersion of CNT-NDs in the epoxy matrix. The heat-transfer channels were built by the venous CNTs cooperating with the coated NDs, which not only plays an effective role of heat conduction for CNTs and NDs, but also avoids the electrical leakage by the protection of NDs surrounding outside of CNTs. Electrical and thermal conductance measurements demonstrate that the influence of the CNT-ND incorporation on the electrical conductance is minor, however, the thermal conductivity is improved significantly for the epoxy filled with CNT-ND.[Figure not available: see fulltext.

  4. Tip-enhanced nano-Raman analytical imaging of locally induced strain distribution in carbon nanotubes.

    Science.gov (United States)

    Yano, Taka-Aki; Ichimura, Taro; Kuwahara, Shota; H'dhili, Fekhra; Uetsuki, Kazumasa; Okuno, Yoshito; Verma, Prabhat; Kawata, Satoshi

    2013-01-01

    Tip-enhanced Raman scattering microscopy is a powerful technique for analysing nanomaterials at high spatial resolution far beyond the diffraction limit of light. However, imaging of intrinsic properties of materials such as individual molecules or local structures has not yet been achieved even with a tip-enhanced Raman scattering microscope. Here we demonstrate colour-coded tip-enhanced Raman scattering imaging of strain distribution along the length of a carbon nanotube. The strain is induced by dragging the nanotube with an atomic force microscope tip. A silver-coated nanotip is employed to enhance and detect Raman scattering from specific locations of the nanotube directly under the tip apex, representing deformation of its molecular alignment because of the existence of local strain. Our technique remarkably provides an insight into localized variations of structural properties in nanomaterials, which could prove useful for a variety of applications of carbon nanotubes and other nanomaterials as functional devices and materials.

  5. Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project - Part 1: calibration, urban enhancements, and uncertainty estimates

    Science.gov (United States)

    Verhulst, Kristal R.; Karion, Anna; Kim, Jooil; Salameh, Peter K.; Keeling, Ralph F.; Newman, Sally; Miller, John; Sloop, Christopher; Pongetti, Thomas; Rao, Preeti; Wong, Clare; Hopkins, Francesca M.; Yadav, Vineet; Weiss, Ray F.; Duren, Riley M.; Miller, Charles E.

    2017-07-01

    We report continuous surface observations of carbon dioxide (CO2) and methane (CH4) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO2 and CH4 measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally. We estimate background mole fractions entering LA using observations from four extra-urban sites including two marine sites located south of LA in La Jolla (LJO) and offshore on San Clemente Island (SCI), one continental site located in Victorville (VIC), in the high desert northeast of LA, and one continental/mid-troposphere site located on Mount Wilson (MWO) in the San Gabriel Mountains. We find that a local marine background can be established to within ˜ 1 ppm CO2 and ˜ 10 ppb CH4 using these local measurement sites. Overall, atmospheric carbon dioxide and methane levels are highly variable across Los Angeles. Urban and suburban sites show moderate to large CO2 and CH4 enhancements relative to a marine background estimate. The USC (University of Southern California) site near downtown LA exhibits median hourly enhancements of ˜ 20 ppm CO2 and ˜ 150 ppb CH4 during 2015 as well as ˜ 15 ppm CO2 and ˜ 80 ppb CH4 during mid-afternoon hours (12:00-16:00 LT, local time), which is the typical period of focus for flux inversions. The estimated measurement uncertainty is typically better than 0.1 ppm CO2 and 1 ppb CH4 based on the repeated standard gas measurements from the LA sites during the last 2 years, similar to Andrews et al. (2014). The largest component of the measurement uncertainty is due to the single-point calibration method; however, the uncertainty in the background mole fraction is much larger than the measurement uncertainty. The background uncertainty for the marine

  6. Carbon materials for enhancing charge transport in the advancements of perovskite solar cells

    Science.gov (United States)

    Hu, Ruiyuan; Chu, Liang; Zhang, Jian; Li, Xing'ao; Huang, Wei

    2017-09-01

    Organic-inorganic halide perovskite solar cells (PSCs) have become a new favorite in the photovoltaic field, due to the boosted efficiency up to 22.1%. Despite a flow of achievements, there are certain challenges to simultaneously meet high efficiency, large scale, low cost and high stability. Due to the low cost, extensive sources, high electrical conductivity and chemical stability, carbon materials have made undeniable contributions to play positive roles in developing PSCs. Carbon materials not only have the favorable conductivity but also bipolar advantage, which can transfer both electrons and holes. In this review, we will discuss how the carbon materials transfer charge or accelerate charge transport by incorporation in PSCs. Carbon materials can replace transparent conductive oxide layers, and enhance electron transport in electron transport layers. Moreover, carbon materials with continuous structure, especially carbon nanotubes and graphene, can provide direct charge transport channel that make them suitable additives or even substitutes in hole transport layers. Especially, the successful application of carbon materials as counter electrodes makes the devices full-printable, low temperature and high stability. Finally, a brief outlook is provided on the future development of carbon materials for PSCs, which are expected to devote more contributions in the future photovoltaic market.

  7. Carbon storage in the Mississippi River delta enhanced by environmental engineering

    Science.gov (United States)

    Shields, Michael R.; Bianchi, Thomas S.; Mohrig, David; Hutchings, Jack A.; Kenney, William F.; Kolker, Alexander S.; Curtis, Jason H.

    2017-11-01

    River deltas have contributed to atmospheric carbon regulation throughout Earth history, but functioning in the modern era has been impaired by reduced sediment loads, altered hydrologic regimes, increased global sea-level rise and accelerated subsidence. Delta restoration involves environmental engineering via river diversions, which utilize self-organizing processes to create prograding deltas. Here we analyse sediment cores from Wax Lake delta, a product of environmental engineering, to quantify the burial of organic carbon. We find that, despite relatively low concentrations of organic carbon measured in the cores (about 0.4%), the accumulation of about 3 T m-2 of sediment over the approximate 60 years of delta building resulted in the burial of a significant amount of organic carbon (16 kg m-2). This equates to an apparent organic carbon accumulation rate of 250 +/- 23 g m-2 yr-1, which implicitly includes losses by carbon emissions and erosion. Our estimated accumulation rate for Wax Lake delta is substantially greater than previous estimates based on the top metre of delta sediments and comparable to those of coastal mangrove and marsh habitats. The sedimentation of carbon at the Wax Lake delta demonstrates the capacity of engineered river diversions to enhance both coastal accretion and carbon burial.

  8. Engineered carbon nanotubes reinforced polymer composites for enhanced thermoelectric performance

    Science.gov (United States)

    Kiran, Raj; Kumar, Anuruddh; Chauhan, Vishal S.; Kumar, Rajeev; Vaish, Rahul

    2017-10-01

    Thermoelectric materials have attracted great attention from researchers because of their unique ability to convert thermal energy to electrical energy and vice versa. Based on the coupled theory of transport between heat and electricity in metals, we have carried out finite element simulations on carbon nanotube (CNT)/polyaniline (PANI) composites to compute effective Seebeck coefficients and figures of merit (FOMs). The present study focuses on the effect of interfacial electrical and thermal conductivities, the volume fraction of CNTs and their inclination on the effective electrical and thermal conductivities and thermoelectric performance. It is interesting to report that effective conductivities strongly depend on interfacial conductance in composites where CNTs are transverse to electrical current and heat flow. Interfaces with electrical and thermal conductance less than 103 S m‑2 and 107 W m‑2 K‑1 respectively isolate CNTs from the matrix. This reduces the effective properties, while the conductivities increase with the CNT content if interfacial conductance is more than these specified values. It was also established that the effective Seebeck coefficient and FOM increase with interfacial electrical conductance, while decreasing with an increase in interfacial thermal conductance. Additionally, the effect of inclination on the electrical and thermal conductivities of composites, the effective Seebeck coefficient and the FOM were analysed. It can be concluded from the study that the Seebeck coefficient and FOM of thermoelectric composites are increased if the CNTs are lying perpendicular to the heat and electrical current flow.

  9. Southern Ocean deep-water carbon export enhanced by natural iron fertilization.

    Science.gov (United States)

    Pollard, Raymond T; Salter, Ian; Sanders, Richard J; Lucas, Mike I; Moore, C Mark; Mills, Rachel A; Statham, Peter J; Allen, John T; Baker, Alex R; Bakker, Dorothee C E; Charette, Matthew A; Fielding, Sophie; Fones, Gary R; French, Megan; Hickman, Anna E; Holland, Ross J; Hughes, J Alan; Jickells, Timothy D; Lampitt, Richard S; Morris, Paul J; Nédélec, Florence H; Nielsdóttir, Maria; Planquette, Hélène; Popova, Ekaterina E; Poulton, Alex J; Read, Jane F; Seeyave, Sophie; Smith, Tania; Stinchcombe, Mark; Taylor, Sarah; Thomalla, Sandy; Venables, Hugh J; Williamson, Robert; Zubkov, Mike V

    2009-01-29

    The addition of iron to high-nutrient, low-chlorophyll regions induces phytoplankton blooms that take up carbon. Carbon export from the surface layer and, in particular, the ability of the ocean and sediments to sequester carbon for many years remains, however, poorly quantified. Here we report data from the CROZEX experiment in the Southern Ocean, which was conducted to test the hypothesis that the observed north-south gradient in phytoplankton concentrations in the vicinity of the Crozet Islands is induced by natural iron fertilization that results in enhanced organic carbon flux to the deep ocean. We report annual particulate carbon fluxes out of the surface layer, at three kilometres below the ocean surface and to the ocean floor. We find that carbon fluxes from a highly productive, naturally iron-fertilized region of the sub-Antarctic Southern Ocean are two to three times larger than the carbon fluxes from an adjacent high-nutrient, low-chlorophyll area not fertilized by iron. Our findings support the hypothesis that increased iron supply to the glacial sub-Antarctic may have directly enhanced carbon export to the deep ocean. The CROZEX sequestration efficiency (the amount of carbon sequestered below the depth of winter mixing for a given iron supply) of 8,600 mol mol(-1) was 18 times greater than that of a phytoplankton bloom induced artificially by adding iron, but 77 times smaller than that of another bloom initiated, like CROZEX, by a natural supply of iron. Large losses of purposefully added iron can explain the lower efficiency of the induced bloom(6). The discrepancy between the blooms naturally supplied with iron may result in part from an underestimate of horizontal iron supply.

  10. Edge effects enhance carbon uptake and its vulnerability to climate change in temperate broadleaf forests.

    Science.gov (United States)

    Reinmann, Andrew B; Hutyra, Lucy R

    2017-01-03

    Forest fragmentation is a ubiquitous, ongoing global phenomenon with profound impacts on the growing conditions of the world's remaining forest. The temperate broadleaf forest makes a large contribution to the global terrestrial carbon sink but is also the most heavily fragmented forest biome in the world. We use field measurements and geospatial analyses to characterize carbon dynamics in temperate broadleaf forest fragments. We show that forest growth and biomass increase by 89 ± 17% and 64 ± 12%, respectively, from the forest interior to edge, but ecosystem edge enhancements are not currently captured by models or approaches to quantifying regional C balance. To the extent that the findings from our research represent the forest of southern New England in the United States, we provide a preliminary estimate that edge growth enhancement could increase estimates of the region's carbon uptake and storage by 13 ± 3% and 10 ± 1%, respectively. However, we also find that forest growth near the edge declines three times faster than that in the interior in response to heat stress during the growing season. Using climate projections, we show that future heat stress could reduce the forest edge growth enhancement by one-third by the end of the century. These findings contrast studies of edge effects in the world's other major forest biomes and indicate that the strength of the temperate broadleaf forest carbon sink and its capacity to mitigate anthropogenic carbon emissions may be stronger, but also more sensitive to climate change than previous estimates suggest.

  11. Enhanced Wettability Modification and CO2 Solubility Effect by Carbonated Low Salinity Water Injection in Carbonate Reservoirs

    Directory of Open Access Journals (Sweden)

    Ji Ho Lee

    2017-01-01

    Full Text Available Carbonated water injection (CWI induces oil swelling and viscosity reduction. Another advantage of this technique is that CO2 can be stored via solubility trapping. The CO2 solubility of brine is a key factor that determines the extent of these effects. The solubility is sensitive to pressure, temperature, and salinity. The salting-out phenomenon makes low saline brine a favorable condition for solubilizing CO2 into brine, thus enabling the brine to deliver more CO2 into reservoirs. In addition, low saline water injection (LSWI can modify wettability and enhance oil recovery in carbonate reservoirs. The high CO2 solubility potential and wettability modification effect motivate the deployment of hybrid carbonated low salinity water injection (CLSWI. Reliable evaluation should consider geochemical reactions, which determine CO2 solubility and wettability modification, in brine/oil/rock systems. In this study, CLSWI was modeled with geochemical reactions, and oil production and CO2 storage were evaluated. In core and pilot systems, CLSWI increased oil recovery by up to 9% and 15%, respectively, and CO2 storage until oil recovery by up to 24% and 45%, respectively, compared to CWI. The CLSWI also improved injectivity by up to 31% in a pilot system. This study demonstrates that CLSWI is a promising water-based hybrid EOR (enhanced oil recovery.

  12. Polyamine is a critical determinant of Pseudomonas chlororaphis O6 for GacS-dependent bacterial cell growth and biocontrol capacity.

    Science.gov (United States)

    Park, Ju Yeon; Kang, Beom Ryong; Ryu, Choong-Min; Anderson, Anne J; Kim, Young Cheol

    2017-09-01

    The Gac/Rsm network regulates, at the transcriptional level, many beneficial traits in biocontrol-active pseudomonads. In this study, we used Phenotype MicroArrays, followed by specific growth studies and mutational analysis, to understand how catabolism is regulated by this sensor kinase system in the biocontrol isolate Pseudomonas chlororaphis O6. The growth of a gacS mutant was decreased significantly relative to that of the wild-type on ornithine and arginine, and on the precursor of these amino acids, N-acetyl-l-glutamic acid. The gacS mutant also showed reduced production of polyamines. Expression of the genes encoding arginine decarboxylase (speA) and ornithine decarboxylases (speC) was controlled at the transcriptional level by the GacS sensor of P. chlororaphis O6. Polyamine production was reduced in the speC mutant, and was eliminated in the speAspeC mutant. The addition of exogenous polyamines to the speAspeC mutant restored the in vitro growth inhibition of two fungal pathogens, as well as the secretion of three biological control-related factors: pyrrolnitrin, protease and siderophore. These results extend our knowledge of the regulation by the Gac/Rsm network in a biocontrol pseudomonad to include polyamine synthesis. Collectively, our studies demonstrate that bacterial polyamines act as important regulators of bacterial cell growth and biocontrol potential. © 2017 BSPP AND JOHN WILEY & SONS LTD.

  13. Enhancing Carbon Stocks and Reducing CO2 Emissions in Agriculture and Natural Resource Management Projects : Toolkit

    OpenAIRE

    World Bank

    2012-01-01

    There is global interest in promoting mitigation and adaptation in agriculture, forest, and other land-use (AFOLU) sectors to address the twin goals of climate change and sustainable development. This guideline deals with how to enhance carbon stocks in general in all land-based projects and its specific relationship with agriculture productivity. It outlines specific steps and procedures ...

  14. Forbs enhance productivity of unfertilised grass-clover leys and support low-carbon bioenergy

    DEFF Research Database (Denmark)

    Cong, Wen-Feng; Jing, Jingying; Rasmussen, Jim

    2017-01-01

    achieved the 60% reduction in GHG emissions compared to fossil fuel, whereas all fertilised mixtures did not meet the 60% reduction target. These findings suggest that including competitive forbs such as plantain in grass-clover mixtures enhances productivity, supporting low-carbon footprint bioenergy...

  15. Enhanced sensing of NH3 gas by decorated multiwalled carbon nanotube

    Science.gov (United States)

    Hasnahena, S. T.; Satpati, Biswarup; Roy, Madhusudan

    2016-05-01

    The present study describes synthesis of Barium Oxide Nanoparticles decorated Multiwalled Carbon Nanotubes and its gas sensing behavior towards NH3 and CO gases. The decorated MWCNT sensor has an enhanced sensing towards NH3 gas compare to pure MWCNT sensor and also has much reduced response and recovery time. The prepared sensing material is characterized by TEM, XRD and Thermal Gravimetric analysis.

  16. Large scale boron carbon nitride nanosheets with enhanced lithium storage capabilities.

    Science.gov (United States)

    Lei, Weiwei; Qin, Si; Liu, Dan; Portehault, David; Liu, Zongwen; Chen, Ying

    2013-01-14

    Few-layered boron carbon nitride nanosheets are synthesized by a simple and environmentally friendly process. The BCN nanosheets have 2-6 atomic layers with high surface area and show enhanced storage performance in lithium batteries, as well as a stable capacity of ~100 mA h g(-1) at 2 A g(-1) for 5000 cycles.

  17. The first carbon-enhanced metal-poor star found in the Sculptor dwarf spheroidal

    NARCIS (Netherlands)

    Skúladóttir, Á.; Tolstoy, E.; Salvadori, S.; Hill, V.; Pettini, M.; Shetrone, M. D.; Starkenburg, E.

    The origin of carbon-enhanced metal-poor (CEMP) stars and their possible connection with the chemical elements produced by the first stellar generation is still highly debated. In contrast to the Galactic halo, not many CEMP stars have been found in the dwarf spheroidal galaxies around the Milky

  18. CO2 Mass transfer model for carbonic anhydrase-enhanced aqueous MDEA solutions

    DEFF Research Database (Denmark)

    Gladis, Arne Berthold; Deslauriers, Maria Gundersen; Neerup, Randi

    2018-01-01

    In this study a CO2 mass transfer model was developed for carbonic anhydrase-enhanced MDEA solutions based on a mechanistic kinetic enzyme model. Four different enzyme models were compared in their ability to predict the liquid side mass transfer coefficient at temperatures in the range of 298...

  19. Carbon-enhanced metal-poor stars: effects of binary evolution at low metallicity

    NARCIS (Netherlands)

    Pols, O.R.; Izzard, R.G.

    2006-01-01

    Recent spectroscopic surveys have revealed a large number of extremely metal-poor stars in the Galactic halo. Many of these stars are being subjected to detailed spectroscopic analysis, and a surprisingly large fraction, about 25 %, turn out to be carbon-rich stars with enhancements of C by as much

  20. Evaluation and Enhancement of Carbon Dioxide Flooding Through Sweep Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Richard

    2009-09-30

    Carbon dioxide displacement is a common improved recovery method applied to light oil reservoirs (30-45{degrees}API). The economic and technical success of CO{sub 2} floods is often limited by poor sweep efficiency or large CO{sub 2} utilization rates. Projected incremental recoveries for CO{sub 2} floods range from 7% to 20% of the original oil in place; however, actual incremental recoveries range from 9% to 15% of the original oil in place, indicating the potential for significant additional recoveries with improved sweep efficiency. This research program was designed to study the effectiveness of carbon dioxide flooding in a mature reservoir to identify and develop methods and strategies to improve oil recovery in carbon dioxide floods. Specifically, the project has focused on relating laboratory, theoretical and simulation studies to actual field performance in a CO{sub 2} flood in an attempt to understand and mitigate problems of areal and vertical sweep efficiency. In this work the focus has been on evaluating the status of existing swept regions of a mature CO{sub 2} flood and developing procedures to improve the design of proposed floods. The Little Creek Field, Mississippi has been studied through laboratory, theoretical, numerical and simulation studies in an attempt to relate performance predictions to historical reservoir performance to determine sweep efficiency, improve the understanding of the reservoir response to CO{sub 2} injection, and develop scaling methodologies to relate laboratory data and simulation results to predicted reservoir behavior. Existing laboratory information from Little Creek was analyzed and an extensive amount of field data was collected. This was merged with an understanding of previous work at Little Creek to generate a detailed simulation study of two portions of the field – the original pilot area and a currently active part of the field. This work was done to try to relate all of this information to an understanding

  1. Treatment of Reactive Black 5 by combined electrocoagulation-granular activated carbon adsorption-microwave regeneration process

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Shih-Hsien, E-mail: shchang@csmu.edu.tw [Department of Public Health, Chung-Shan Medical University, 110 Chen-Kuo N. Road, Taichung 402, Taiwan (China); Wang, Kai-Sung; Liang, Hsiu-Hao; Chen, Hsueh-Yu; Li, Heng-Ching; Peng, Tzu-Huan [Department of Public Health, Chung-Shan Medical University, 110 Chen-Kuo N. Road, Taichung 402, Taiwan (China); Su, Yu-Chun; Chang, Chih-Yuan [Institute of Environmental Engineering, National Chiao-Tung University, Hsinchu, 300, Taiwan (China)

    2010-03-15

    Treatment of an azo dye, Reactive Black 5 (RB5) by combined electrocoagulation-activated carbon adsorption-microwave regeneration process was evaluated. The toxicity was also monitored by the Vibrio fischeri light inhibition test. GAC of 100 g L{sup -1} sorbed 82% of RB5 (100 mg L{sup -1}) within 4 h. RB5-loaded GAC was not effectively regenerated by microwave irradiation (800 W, 30 s). Electrocoagulation showed high decolorization of RB5 within 8 min at pH{sub 0} of 7, current density of 277 A m{sup -2}, and NaCl of 1 g L{sup -1}. However, 61% COD residue remained after treatment and toxicity was high (100% light inhibition). GAC of 20 g L{sup -1} effectively removed COD and toxicity of electrocoagulation-treated solution within 4 h. Microwave irradiation effectively regenerated intermediate-loaded GAC within 30 s at power of 800 W, GAC/water ratio of 20 g L{sup -1}, and pH of 7.8. The adsorption capacity of GAC for COD removal from the electrocoagulation-treated solution did not significantly decrease at the first 7 cycles of adsorption/regeneration. The adsorption capacity of GAC for removal of both A{sub 265} (benzene-related groups) and toxicity slightly decreased after the 6th cycle.

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

    Science.gov (United States)

    Zhang, Chao; Chen, Yin-Guang

    2013-07-01

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

  3. Enhanced water repellency of surfaces coated with multiscale carbon structures

    Science.gov (United States)

    Marchalot, Julien; Ramos, Stella. M. M.; Pirat, Christophe; Journet, Catherine

    2018-01-01

    Low cost and well characterized superhydrophobic surfaces are frequently required for industrial applications. Materials are commonly structured at the micro or nano scale. Surfaces decorated with nanotube derivatives synthesized by plasma enhanced chemical vapor deposition (PECVD) are of particular interest, since suitable modifications in the growth parameters can lead to numerous designs. In this article, we present surfaces that are selected for their specific wetting features with patterns ranging from dense forests to jungles with concave (re-entrant) surface such as flake-like multiscale roughness. Once these surfaces are functionalized adequately, their wetting properties are investigated. Their ability to sustain a superhydrophobic state for sessile water drops is examined. Finally, we propose a design to achieve a robust so-called ;Fakir; state, even for micrometer-sized drops, whereas with classic nanotubes forests it is not achievable. Thus, the drop remains on the apex of the protrusions with a high contact angle and a low contact angle hysteresis, while the surface features demonstrate good mechanical resistance against capillary forces.

  4. Enhanced oil recovery & carbon sequestration building on successful experience

    Energy Technology Data Exchange (ETDEWEB)

    Stern, Fred [BEPC (United States)

    2008-07-15

    In this paper it is spoken of the experiences in the capture and sequestration of CO{sub 2} in the companies Basin Electric Power Cooperative (BEPC) and Dakota Gasification Company (DGC); their by-products are mentioned and what these companies are making to control the CO{sub 2} emissions. Their challenges to compress CO{sub 2} are presented and how they have reduced the CO{sub 2} emissions in the DGC of the 2000 to the 2008; how they use CO{sub 2} to enhance the oil recovery and which are their challenges in the CO{sub 2} transport. [Spanish] En esta ponencia se habla de las experiencias en la captura y secuestro de CO{sub 2} en las empresas Basin Electic Power Cooperative (BEPC) y Dakota Gasification Campany (DGC); se mencionan sus subproductos y que estan haciendo estas empresas para controlar las emisiones de CO{sub 2}. Se presentan sus retos para comprimir CO{sub 2} y como han reducido las emisiones de CO{sub 2} en la DGC del 2000 al 2008; como utilizan el CO{sub 2} para mejorar la recuperacion de petroleo y sus cuales son retos en el transporte de CO{sub 2}.

  5. Enhanced adsorption of perfluorooctane sulfonate and perfluorooctanoate by bamboo-derived granular activated carbon.

    Science.gov (United States)

    Deng, Shubo; Nie, Yao; Du, Ziwen; Huang, Qian; Meng, Pingping; Wang, Bin; Huang, Jun; Yu, Gang

    2015-01-23

    A bamboo-derived granular activated carbon with large pores was successfully prepared by KOH activation, and used to remove perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from aqueous solution. The granular activated carbon prepared at the KOH/C mass ratio of 4 and activation temperature of 900°C had fast and high adsorption for PFOS and PFOA. Their adsorption equilibrium was achieved within 24h, which was attributed to their fast diffusion in the micron-sized pores of activated carbon. This granular activated carbon exhibited the maximum adsorbed amount of 2.32mmol/g for PFOS and 1.15mmol/g for PFOA at pH 5.0, much higher than other granular and powdered activated carbons reported. The activated carbon prepared under the severe activation condition contained many enlarged pores, favorable for the adsorption of PFOS and PFOA. In addition, the spent activated carbon was hardly regenerated in NaOH/NaCl solution, while the regeneration efficiency was significantly enhanced in hot water and methanol/ethanol solution, indicating that hydrophobic interaction was mainly responsible for the adsorption. The regeneration percent was up to 98% using 50% ethanol solution at 45°C. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Carbon Coated Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Dielectric Performance.

    Science.gov (United States)

    Yang, Minhao; Zhao, Hang; He, Delong; Hu, Chaohe; Chen, Haowei; Bai, Jinbo

    2017-07-03

    Carbon coated boron nitride nanosheets (BNNSs@C) hybrids with different carbon contents were synthesized by a chemical vapor deposition (CVD) method. The content of carbon in as-obtained BNNSs@C hybrids could be precisely adjusted from 2.50% to 22.62% by controlling the carbon deposition time during the CVD procedure. Afterward, the BNNSs@C hybrids were subsequently incorporated into the polyvinylidene fluoride (PVDF) matrix to fabricate the BNNSs@C/PVDF nanocomposites through a combination of solution and melting blending methods. The dielectric properties of the as-obtained BNNSs@C/PVDF nanocomposites could be accurately tuned by adjusting the carbon content. The resultant nanocomposites could afford a high dielectric constant about 39 (10³ Hz) at BNNSs@C hybrids loading of 30 vol %, which is 4.8 times larger than that of pristine BNNSs-filled ones at the same filler loading, and 3.5 times higher than that of pure PVDF matrix. The largely enhanced dielectric performance could be ascribed to the improved interfacial polarizations of BNNSs/carbon and carbon/PVDF interfaces. The approach reported here offers an effective and alternative method to fabricate high-performance dielectric nanocomposites, which could be potentially applied to the embedded capacitors with high dielectric performance.

  7. Morphological changes during enhanced carbonation of asbestos containing material and its comparison to magnesium silicate minerals

    Energy Technology Data Exchange (ETDEWEB)

    Gadikota, Greeshma [Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, NY 10027 (United States); Natali, Claudio; Boschi, Chiara [Institute of Geosciences and Earth Resources – National Research Council, Pisa (Italy); Park, Ah-Hyung Alissa, E-mail: ap2622@columbia.edu [Department of Earth and Environmental Engineering, Columbia University, 500 West 120th Street, New York, NY 10027 (United States); Department of Chemical Engineering, Columbia University, 500 West 120th Street, New York, NY 10027 (United States); Lenfest Center for Sustainable Energy, Columbia University, 500 West 120th Street, New York, NY 10027 (United States)

    2014-01-15

    The disintegration of asbestos containing materials (ACM) over time can result in the mobilization of toxic chrysotile ((Mg, Fe){sub 3}Si{sub 2}O{sub 5}(OH){sub 4})) fibers. Therefore, carbonation of these materials can be used to alter the fibrous morphology of asbestos and help mitigate anthropogenic CO{sub 2} emissions, depending on the amount of available alkaline metal in the materials. A series of high pressure carbonation experiments were performed in a batch reactor at P{sub CO2} of 139 atm using solvents containing different ligands (i.e., oxalate and acetate). The results of ACM carbonation were compared to those of magnesium silicate minerals which have been proposed to permanently store CO{sub 2} via mineral carbonation. The study revealed that oxalate even at a low concentration of 0.1 M was effective in enhancing the extent of ACM carbonation and higher reaction temperatures also resulted in increased ACM carbonation. Formation of phases such as dolomite ((Ca, Mg)(CO{sub 3}){sub 2}), whewellite (CaC{sub 2}O{sub 4}·H{sub 2}O) and glushinskite (MgC{sub 2}O{sub 4}·2H{sub 2}O) and a reduction in the chrysotile content was noted. Significant changes in the particle size and surface morphologies of ACM and magnesium silicate minerals toward non-fibrous structures were observed after their carbonation.

  8. Facile synthesis of ultrahigh-surface-area hollow carbon nanospheres for enhanced adsorption and energy storage

    Science.gov (United States)

    Xu, Fei; Tang, Zhiwei; Huang, Siqi; Chen, Luyi; Liang, Yeru; Mai, Weicong; Zhong, Hui; Fu, Ruowen; Wu, Dingcai

    2015-01-01

    Exceptionally large surface area and well-defined nanostructure are both critical in the field of nanoporous carbons for challenging energy and environmental issues. The pursuit of ultrahigh surface area while maintaining definite nanostructure remains a formidable challenge because extensive creation of pores will undoubtedly give rise to the damage of nanostructures, especially below 100 nm. Here we report that high surface area of up to 3,022 m2 g−1 can be achieved for hollow carbon nanospheres with an outer diameter of 69 nm by a simple carbonization procedure with carefully selected carbon precursors and carbonization conditions. The tailor-made pore structure of hollow carbon nanospheres enables target-oriented applications, as exemplified by their enhanced adsorption capability towards organic vapours, and electrochemical performances as electrodes for supercapacitors and sulphur host materials for lithium–sulphur batteries. The facile approach may open the doors for preparation of highly porous carbons with desired nanostructure for numerous applications. PMID:26072734

  9. Enhancing the Properties of Carbon and Gold Substrates by Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Harnisch, Jennifer Anne [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The properties of both carbon and gold substrates are easily affected by the judicious choice of a surface modification protocol. Several such processes for altering surface composition have been published in literature. The research presented in this thesis primarily focuses on the development of on-column methods to modify carbon stationary phases used in electrochemically modulated liquid chromatography (EMLC). To this end, both porous graphitic carbon (PGC) and glassy carbon (GC) particles have been modified on-column by the electroreduction of arenediazonium salts and the oxidation of arylacetate anions (the Kolbe reaction). Once modified, the carbon stationary phases show enhanced chromatographic performance both in conventional liquid chromatographic columns and EMLC columns. Additionally, one may also exploit the creation of aryl films to by electroreduction of arenediazonium salts in the creation of nanostructured materials. The formation of mercaptobenzene film on the surface of a GC electrode provides a linking platform for the chemisorption of gold nanoparticles. After deposition of nanoparticles, the surface chemistry of the gold can be further altered by self-assembled monolayer (SAM) formation via the chemisorption of a second thiol species. Finally, the properties of gold films can be altered such that they display carbon-like behavior through the formation of benzenehexathiol (BHT) SAMs. BHT chemisorbs to the gold surface in a previously unprecedented planar fashion. Carbon and gold substrates can be chemically altered by several methodologies resulting in new surface properties. The development of modification protocols and their application in the analytical arena is considered herein.

  10. Enhanced electron field emission from carbon nanotubes irradiated by energetic C ions.

    Science.gov (United States)

    Sun, Peng-Cheng; Deng, Jian-Hua; Cheng, Guo-An; Zheng, Rui-Ting; Ping, Zhao-Xia

    2012-08-01

    The field emission performance and structure of the vertically aligned multi-walled carbon nanotube arrays irradiated by energetic C ion with average energy of 40 keV have been investigated. During energetic C ion irradiation, the curves of emission current density versus the applied field of samples shift firstly to low applied fields when the irradiation doses are less than 9.6 x 10(16) cm(-2), and further increase of dose makes the curves reversing to a high applied field, which shows that high dose irradiation in carbon nanotube arrays makes their field emission performance worse. After energetic ion irradiation with a dose of 9.6 x 1016 cm(-2), the turn-on electric field and the threshold electric field of samples decreased from 0.80 and 1.13 V/microm to 0.67 and 0.98 V/microm respectively. Structural analysis of scanning electron microscopy, transmission electron microscopy and Raman spectroscopy indicates that the amorphous carbon nanowire/carbon nanotube hetero nano-structures have been fabricated in the C ion irradiated carbon nanotubes. The enhancement of electron field emission is due to the formation of amorphous carbon nanowires at the tip of carbon nanotube arrays, which is an electron emitting material with low work function.

  11. Momentum angular mapping of enhanced Raman scattering of single-walled carbon nanotube

    Science.gov (United States)

    Rai, Padmnabh; Singh, Tapender; Brulé, Thibault; Bouhelier, Alexandre; Finot, Eric

    2017-07-01

    We perform momentum mapping of the Raman scattering of individual single-walled carbon nanotubes (SWNTs) or thin ropes of SWNTs enhanced by surface plasmons sustained by either a linear chain of nanoantennas or flower-shaped nanoparticles. The momentum spectroscopy of Raman scattering of the carbon nanotube (CNT) demonstrates the direct verification of momentum selection rules and identifies the characteristic bands of the molecules or the nanomaterials under scrutiny. The characteristic vibrational signatures of the D, G-, and G bands provide an isotropic response in k-space irrespective of the arrangement of the enhancing platform. However, other dispersive or double resonance bands, such as D-, D+, D', M, and iTOLA bands appear as a dipolar emission oriented towards the long axis of the CNT regardless of the CNT orientation but strongly depend on the patterning of enhancement of the electromagnetic field.

  12. Bacterial Community Structure Shifted by Geosmin in Granular Activated Carbon System of Water Treatment Plants.

    Science.gov (United States)

    Pham, Ngoc Dung; Lee, Eun-Hee; Chae, Seon-Ha; Cho, Yongdeok; Shin, Hyejin; Son, Ahjeong

    2016-01-01

    We investigated the relation between the presence of geosmin in water and the bacterial community structure within the granular activated carbon (GAC) system of water treatment plants in South Korea. GAC samples were collected in May and August of 2014 at three water treatment plants (Sungnam, Koyang, and Yeoncho in Korea). Dissolved organic carbon and geosmin were analyzed before and after GAC treatment. Geosmin was found in raw water from Sungnam and Koyang water treatment plants but not in that from Yeoncho water treatment plant. Interestingly, but not surprisingly, the 16S rRNA clone library indicated that the bacterial communities from the Sungnam and Koyang GAC systems were closely related to geosmin-degrading bacteria. Based on the phylogenetic tree and multidimensional scaling plot, bacterial clones from GAC under the influence of geosmin were clustered with Variovorax paradoxus strain DB 9b and Comamonas sp. DB mg. In other words, the presence of geosmin in water might have inevitably contributed to the growth of geosmin degraders within the respective GAC system.

  13. Surface modified PLGA/carbon nanofiber composite enhances articular chondrocyte functions

    Science.gov (United States)

    Park, Grace Eunseung

    Since articular cartilage has a limited self regeneration capability, alternative methods are needed for repairing cartilage defects. The purpose of the present in vitro study was to explore the effects of material surface properties and external stimulation on chondrocyte (cartilage-synthesizing cell) functions. Based on this information, a goal of this research was to propose a scaffold composite material for enhancing articular chondrocyte function. To improve functions of chondrocytes, material (namely, poly(lactic-co-glycolic acid); PLGA) surfaces were modified via chemical (NaOH) etching techniques. Chondrocytes were cultured on surface-modified 2-D PLGA films and 3-D PLGA tissue engineering scaffolds, which were created by a salt-leaching method. Carbon nanofibers were imprinted on PLGA matrices in an aligned pattern for controlled electrically-active surface features. Electrical stimulation was applied to expedite and enhance chondrocyte functions. Results demonstrated that both NaOH-treated 2-D and 3-D substrates enhanced chondrocyte functions (cell numbers as well as extracellular matrix production) compared to non-treated PLGA substrates. Furthermore, chondrocytes preferred to attach along the carbon nanofiber patterns imprinted on PLGA. Electrical stimulation also enhanced chondrocyte functions on carbon nanofiber/PLGA composites. Underlying material properties that may have enhanced chondrocyte functions include a more hydrophilic surface, surface energy differences due to the presence of carbon nanofibers, increased surface area, altered porosity, and a greater degree of nanometer roughness. Moreover, these altered surface properties positively influenced select protein adsorption that controlled subsequent chondrocyte adhesion. Collectively, this study provided a scaffold model for osteochondral defects that can be synthesized using the above techniques and a layer by layer approach to accommodate the property differences in each layer of natural

  14. Enhancement of Field Emission Properties of Carbon Nanotubes by ECR-Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Javid Ali

    2014-01-01

    Full Text Available We report a significant improvement in electron field emission property of carbon nanotubes film by using an electron cyclotron resonance plasma treatment. Our research results reveal that plasma treatment can modify the surface morphology and enhance the field emission characteristics of carbon nanotubes. Raman spectra indicate that plasma treated CNTs sample has lesser defects. Before plasma treatment, low current density of 6.5 mA/cm2 at 3.0 V/μm and at a high turn-on field Eto of 2.4 V/μm was observed. ECR plasma treated CNTs showed a high current density of 20.0 mA/cm2 at 3.0 V/μm and at a low Eto of 1.6 V/μm. The calculated enhancement factors are 694 and 8721 for ECR-plasma untreated and treated carbon nanotubes, respectively. We found an increase in the enhancement factor and emission current after the ECR-plasma treatment. This may be attributed to creation of geometrical features through the removal of amorphous carbon and catalyst particles.

  15. Selective enhancement and verification of woody biomass digestibility as a denitrification carbon source.

    Science.gov (United States)

    Hu, Rongting; Zheng, Xilai; Xin, Jia; Sun, Zhaoyue; Zheng, Tianyuan

    2017-11-01

    The denitrification efficiency of woody biomass as carbon source is low because of its poor carbon availability. In this study, representative poplar sawdust was pretreated with lime and peracetic acid to enhance the biomass digestibility to different degrees; sawdust was then mixed with soil to investigate its denitrification efficiency. Under controllable conditions (25-95°C, 12-24h, varying dosages), sawdust digestibility (characterized by reducing sugar yield) was selectively enhanced 1.0-21.8 times over that of the raw sawdust (28.8mgeq.glucoseg-1 dry biomass). This increase was mainly attributed to the removal of lignin from the biomass. As a carbon source, the sawdust (digestibility enhanced by 5.4 times) increased the nitrate removal rate by 4.7 times, without N2O emission. However, the sawdust with high digestibility (12.6 or 18.0 times), despite releasing more dissolved organic carbon (DOC), did not exhibit further increase in denitrification efficiency, and emitted N2O. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Apparent Enhanced Solubility of Single-Wall Carbon Nanotubes in a Deuterated Acid Mixture

    Directory of Open Access Journals (Sweden)

    T. Ramanathan

    2008-01-01

    Full Text Available An apparent enhanced solubility of single-wall carbon nanotubes (SWNTs in the deuterated form of the standard 3 : 1 sulfuric (H2SO4 to nitric (HNO3 acid mixture treatment is reported and attributed to the stronger interaction of deuterium bonds with the single-wall carbon nanotube surface. UV-Visible spectroscopy was used to characterize the apparent enhanced solubility of the SWNTs treated in deuterated forms of the acid mixture in comparison to the standard acid mix, while FTIR was used to analyze the nature of the functional groups generated on the SWNTs as a result of the different acid treatments. The apparent enhanced solubility reported here is consistent with the limited number of computational and experimental results published in the literature regarding the interaction of carbon nanotubes with deuterated solvents; however, a detailed understanding of the underlying mechanism responsible for this observation is currently lacking. The apparent increased solubility observed here could potentially be utilized in many applications where carbon nanotube dispersion is required.

  17. Enhancement in ballistic performance of composite hard armor through carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Jason Gibson

    2013-12-01

    Full Text Available The use of carbon nanotubes in composite hard armor is discussed in this study. The processing techniques to make various armor composite panels consisting of Kevlar®29 woven fabric in an epoxy matrix and the subsequent V50 test results for both 44 caliber soft-point rounds and 30 caliber FSP (fragment simulated projectile threats are presented. A 6.5% improvement in the V50 test results was found for a combination of 1.65 wt% loading of carbon nanotubes and 1.65 wt% loading of milled fibers. The failure mechanism of carbon nanotubes during the ballistic event is discussed through scanning electron microscope images of the panels after the failure. Raman Spectroscopy was also utilized to evaluate the residual strain in the Kevlar®29 fibers post shoot. The Raman Spectroscopy shows a Raman shift of 25 cm−1 for the Kevlar®29 fiber utilized in the composite panel that had an enhancement in the V50 performance by using milled fiber and multi-walled carbon nanotubes. Evaluating both scenarios where an improvement was made and other panels without any improvement allows for understanding of how loading levels and synergistic effects between carbon nanotubes and milled fibers can further enhance ballistic performance.

  18. Integrated Mid-Continent Carbon Capture, Sequestration & Enhanced Oil Recovery Project

    Energy Technology Data Exchange (ETDEWEB)

    Brian McPherson

    2010-08-31

    A consortium of research partners led by the Southwest Regional Partnership on Carbon Sequestration and industry partners, including CAP CO2 LLC, Blue Source LLC, Coffeyville Resources, Nitrogen Fertilizers LLC, Ash Grove Cement Company, Kansas Ethanol LLC, Headwaters Clean Carbon Services, Black & Veatch, and Schlumberger Carbon Services, conducted a feasibility study of a large-scale CCS commercialization project that included large-scale CO{sub 2} sources. The overall objective of this project, entitled the 'Integrated Mid-Continent Carbon Capture, Sequestration and Enhanced Oil Recovery Project' was to design an integrated system of US mid-continent industrial CO{sub 2} sources with CO{sub 2} capture, and geologic sequestration in deep saline formations and in oil field reservoirs with concomitant EOR. Findings of this project suggest that deep saline sequestration in the mid-continent region is not feasible without major financial incentives, such as tax credits or otherwise, that do not exist at this time. However, results of the analysis suggest that enhanced oil recovery with carbon sequestration is indeed feasible and practical for specific types of geologic settings in the Midwestern U.S.

  19. Enhanced CO2 Adsorption on Activated Carbon Fibers Grafted with Nitrogen-Doped Carbon Nanotubes

    Science.gov (United States)

    Chiang, Yu-Chun; Hsu, Wei-Lien; Lin, Shih-Yu; Juang, Ruey-Shin

    2017-01-01

    In this paper, multiscale composites formed by grafting N-doped carbon nanotubes (CNs) on the surface of polyamide (PAN)-based activated carbon fibers (ACFs) were investigated and their adsorption performance for CO2 was determined. The spaghetti-like and randomly oriented CNs were homogeneously grown onto ACFs. The pre-immersion of cobalt(II) ions for ACFs made the CNs grow above with a large pore size distribution, decreased the oxidation resistance, and exhibited different predominant N-functionalities after chemical vapor deposition processes. Specifically, the CNs grafted on ACFs with or without pre-immersion of cobalt(II) ions were characterized by the pyridine-like structures of six-member rings or pyrrolic/amine moieties, respectively. In addition, the loss of microporosity on the specific surface area and pore volume exceeded the gain from the generation of the defects from CNs. The adsorption capacity of CO2 decreased gradually with increasing temperature, implying that CO2 adsorption was exothermic. The adsorption capacities of CO2 at 25 °C and 1 atm were between 1.53 and 1.92 mmol/g and the Freundlich equation fit the adsorption data well. The isosteric enthalpy of adsorption, implying physical adsorption, indicated that the growth of CNTs on the ACFs benefit CO2 adsorption. PMID:28772870

  20. Enhanced CO2 Adsorption on Activated Carbon Fibers Grafted with Nitrogen-Doped Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yu-Chun Chiang

    2017-05-01

    Full Text Available In this paper, multiscale composites formed by grafting N-doped carbon nanotubes (CNs on the surface of polyamide (PAN-based activated carbon fibers (ACFs were investigated and their adsorption performance for CO2 was determined. The spaghetti-like and randomly oriented CNs were homogeneously grown onto ACFs. The pre-immersion of cobalt(II ions for ACFs made the CNs grow above with a large pore size distribution, decreased the oxidation resistance, and exhibited different predominant N-functionalities after chemical vapor deposition processes. Specifically, the CNs grafted on ACFs with or without pre-immersion of cobalt(II ions were characterized by the pyridine-like structures of six-member rings or pyrrolic/amine moieties, respectively. In addition, the loss of microporosity on the specific surface area and pore volume exceeded the gain from the generation of the defects from CNs. The adsorption capacity of CO2 decreased gradually with increasing temperature, implying that CO2 adsorption was exothermic. The adsorption capacities of CO2 at 25 °C and 1 atm were between 1.53 and 1.92 mmol/g and the Freundlich equation fit the adsorption data well. The isosteric enthalpy of adsorption, implying physical adsorption, indicated that the growth of CNTs on the ACFs benefit CO2 adsorption.

  1. Ferric oxide nanoparticles decorated carbon nanotubes and carbon nanofibers: From synthesis to enhanced removal of phenol

    Directory of Open Access Journals (Sweden)

    Hamza A. Asmaly

    2015-09-01

    Full Text Available In this work, ferric oxide nanoparticle decorated carbon fibers and carbon nanotubes (CNF/Fe2O3 and CNT/Fe2O3 were synthesized and characterized by scanning electron microscopy (SEM, thermogravimetric analysis (TGA, energy dispersive X-ray spectroscopy (EDS, transmission electron microscopy (TEM, X-ray diffraction (XRD, zeta potential and BET surface area analyzer. The prepared nanocomposites were evaluated or the removal of phenol ions from aqueous solution. The effects of experimental parameters, such as shaking speed, pH, contact time, adsorbent dosage and initial concentration, were evaluated for the phenol removal efficiency. The adsorption experimental data were represented by both the Langmuir and Freundlich isotherm models. The Langmuir isotherm model best fitted the data on the adsorption of phenol, with a high correlation coefficient. The adsorption capacities, as determined by the Langmuir isotherm model were 0.842, 1.098, 1.684 and 2.778 mg/g for raw CNFs, raw CNTs, CNF–Fe2O3 and CNT–Fe2O3, respectively.

  2. Carbon Ion Implantation: A Good Method to Enhance the Biocompatibility of Silicone Rubber.

    Science.gov (United States)

    Zhou, Xin; Chen, Xing; Mao, Tong-cun; Li, Xiang; Shi, Xiao-hua; Fan, Dong-li; Zhang, Yi-ming

    2016-04-01

    Silicone rubber and silicone rubber-based materials have been used as medical tissue implants in the field of plastic surgery for many years, but there are still some reports of adverse reactions to long-term implants. Earlier studies have shown that ion implantation could enhance the biocompatibility of biomaterials. However, whether ion implantation has a good effect on silicone rubber is unknown. Three types of carbon ion silicone rubber were obtained by implanting three doses of carbon ions. Then, the antibacterial adhesion properties and the in vivo host responses were evaluated. The antibacterial adhesion properties were examined by plate colony counting, fluorescence staining, and scanning electron microscopic observation. The host responses were evaluated by surveying inflammation and fiber capsule formation that developed after subcutaneous implantation in Sprague-Dawley rats for 7, 30, 90, and 180 days. In addition, the possible mechanism by which ion implantation enhanced the biocompatibility of the biomaterial was investigated and discussed. Carbon ion silicone rubber exhibits less bacterial adhesion, less collagen deposition, and thinner and weaker tissue capsules. Immunohistochemical staining results for CD4, tumor necrosis factor-α, α-smooth muscle actin, and elastin showed the possible mechanism enhancing the biocompatibility of silicone rubber. These data indicate that carbon ion silicone rubber exhibits good antibacterial adhesion properties and triggers thinner and weaker tissue capsules. In addition, high surface roughness and high zeta potential may be the main factors that induce the unique biocompatibility of carbon ion silicone rubber. Ion implantation should be considered for further investigation and application, and carbon ion silicone rubber could be a better biomaterial to decrease silicone rubber-initiated complications.

  3. Enhancing the Porosity of Mesoporous Carbon-Templated ZSM-5 by Desilication

    DEFF Research Database (Denmark)

    Holm, Martin Spangsberg; Egeblad, Kresten; Vennestrøm, Peter Nicolai Ravnborg

    2008-01-01

    A tunable desilication protocol applied on a mesoporous ZSM-5 zeolite synthesized by carbon-templating is reported. The strategy enables a systematic manufacture of zeolite catalysts with moderate to very high mesoporosities. Coupling carbon-templating and desilication thus allow for more than...... a doubling of the original mesopore volume and mesopore surface area. The porosity effect arising from various treatment times and base amounts in the media has been thoroughly mapped. Initially, small mesopores are created, and as desilication strength increases the average mesopore size enhances...

  4. Yield Strength Enhancement by Carbon Trapping in Ferrite of the Quenching and Partitioning Steel

    Science.gov (United States)

    Chen, P.; Wang, G. D.; Ceguerra, A. V.; Breen, A. J.; Ringer, S. P.; Xiong, X. C.; Lu, Q.; Wang, J. F.; Yi, H. L.

    2018-01-01

    The split quenching and partitioning (S-QP) process allows researchers to investigate microstructure and properties separately, i.e., before and after partitioning. After the partitioning process, the yield strength increases by approximately 300 MPa in the ferrite-bearing δ-quenching and partitioning ( δ-QP) steel. We propose that carbon trapping in dislocations at the ferrite grain boundaries during partitioning process is responsible for the yield strength enhancement of ferrite. Combined transmission electron microscopy and 3D atom probe tomography observations demonstrate carbon atoms segregating in dislocations. The mechanisms for the high yield strength of ferrite presented QP steels are clarified for the first time in this research.

  5. Modelling the nucleosynthetic properties of carbon-enhanced metal-poor RR Lyrae stars

    OpenAIRE

    Stancliffe, Richard J.; Kennedy, Catherine R.; Lau, Herbert H. B.; Beers, Timothy C.

    2013-01-01

    Certain carbon-enhanced metal-poor stars likely obtained their composition via pollution from some of the earliest generations of asymptotic giant branch stars and as such provide important clues to early Universe nucleosynthesis. Recently, Kinman et al. discovered that the highly carbon- and barium-enriched metal-poor star SDSS J1707+58 is in fact an RR Lyrae pulsator. This gives us an object in a definite evolutionary state where the effects of dilution of material during the Main Sequence ...

  6. Enhancement of oxygen reduction activity of nanoshell carbons by introducing nitrogen atoms from metal phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Ozaki, Jun-ichi, E-mail: jozaki@cee.gunma-u.ac.j [Department of Chemical and Environmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Tanifuji, Shin-ichi; Furuichi, Atsuya; Yabutsuka, Katsutoshi [Department of Chemical and Environmental Engineering, Graduate School of Engineering, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515 (Japan)

    2010-02-15

    Nanoshell carbon is a type of catalytically grown nanocarbon with a hollow, round, shell-like structure, with a diameter in the range of approximately 20-50 nm. It has been shown to possess the electrocatalytic activity for oxygen reduction reaction (ORR) and is also expected to be a non-Pt catalyst for polymer electrolyte fuel cells. This paper reports the synergetic enhancement of the ORR activity of nanoshell carbons caused by the coexistence of nitrogen atoms. The nanoshell carbons were prepared by the carbonization of furan resin in the presence of acetylacetonates (AAs) and of phthalocyanines (Pcs), which contained Fe, Co, and Ni. The Pc-derived nanoshells (MP-T series; M = Co or Fe, T = carbonization temperature) showed higher ORR activities than the AA-derived nanoshells (MA-T series; M = Co or Fe, T = carbonization temperature) when the same metal elements were employed. An XPS study revealed that nitrogen species were introduced to the surface of the nanoshells when Pcs were used as the nanoshell-forming catalysts, and that no metal species remained on the nanoshells. Principally, the ORR activity of the carbons was governed by the presence of the nanoshells and further enhancement could be achieved by the introduction of nitrogen atoms. 0.78 V of OCV and 0.21 W cm{sup -2} of the maximum power density were observed for a fuel cell whose MEA consisted of 3CoP1000 cathode and a commercial Pt/C anode, when it was operated at 80 deg. C under a pressurized condition of 0.35 MPa.

  7. Enhancement of minority carrier injection in ambipolar carbon nanotube transistors using double-gate structures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bongjun; Liang, Kelly; Dodabalapur, Ananth, E-mail: ananth.dodabalapur@engr.utexas.edu [Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758 (United States); Geier, Michael L.; Hersam, Mark C. [Department of Materials Science and Engineering and Department of Chemistry, Northwestern University, Evanston, Illinois 60208 (United States)

    2016-07-11

    We show that double-gate ambipolar thin-film transistors can be operated to enhance minority carrier injection. The two gate potentials need to be significantly different for enhanced injection to be observed. This enhancement is highly beneficial in devices such as light-emitting transistors where balanced electron and hole injections lead to optimal performance. With ambipolar single-walled carbon nanotube semiconductors, we demonstrate that higher ambipolar currents are attained at lower source-drain voltages, which is desired for portable electronic applications, by employing double-gate structures. In addition, when the two gates are held at the same potential, the expected advantages of the double-gate transistors such as enhanced on-current are also observed.

  8. Sources and delivery of carbon dioxide for enhanced oil recovery. Final report, October 1977--December 1978

    Energy Technology Data Exchange (ETDEWEB)

    Hare, M.; Perlich, H.; Robinson, R.; Shah, M.; Zimmerman, F.

    1978-12-01

    Results are presented from a comprehensive study by Pullman Kellogg, with assistance from Gulf Universities Research Consortium (GURC) and National Cryo-Chemics Incorporated (NCI), of the carbon dioxide supply situation for miscible flooding operations to enhance oil recovery. A survey of carbon dioxide sources within the geographic areas of potential EOR are shown on four regional maps with the tabular data for each region to describe the sources in terms of quantity and quality. Evaluation of all the costs, such as purchase, production, processing, and transportation, associated with delivering the carbon dioxide from its source to its destination are presented. Specific cases to illustrate the use of the maps and cost charts generated in this study have been examined.

  9. Observation of large enhancements of charge exchange cross sections with neutron-rich carbon isotopes

    Science.gov (United States)

    Tanihata, I.; Terashima, S.; Kanungo, R.; Ameil, F.; Atkinson, J.; Ayyad, Y.; Cortina-Gil, D.; Dillmann, I.; Estradé, A.; Evdokimov, A.; Farinon, F.; Geissel, H.; Guastalla, G.; Janik, R.; Knoebel, R.; Kurcewicz, J.; Litvinov, Yu. A.; Marta, M.; Mostazo, M.; Mukha, I.; Nociforo, C.; Ong, H. J.; Pietri, S.; Prochazka, A.; Scheidenberger, C.; Sitar, B.; Strmen, P.; Takechi, M.; Tanaka, J.; Toki, H.; Vargas, J.; Winfield, J. S.; Weick, H.

    2016-04-01

    Production cross sections of nitrogen isotopes from high-energy (˜ 950 MeV per nucleon) carbon isotopes on hydrogen and carbon targets have been measured for the first time for a wide range of isotopes (A = 12 to 19). The fragment separator FRS at GSI was used to deliver C-isotope beams. The cross sections of the production of N-isotopes were determined by charge measurements of forward-going fragments. The cross sections show a rapid increase with the number of neutrons in the projectile. Since the production of nitrogen is mostly due to charge-exchange (Cex) reactions below the proton separation energies, the present data suggests a concentration of Gamow-Teller and/or Fermi transition strength at low excitation energies for neutron-rich carbon isotopes. It was also observed that the Cex cross sections were enhanced much more strongly for neutron-rich isotopes in the C-target data.

  10. Defect-enhanced Rashba spin-polarized currents in carbon nanotubes

    Science.gov (United States)

    Santos, Hernán; Chico, Leonor; Alvarellos, J. E.; Latgé, A.

    2017-10-01

    The production of spin-polarized currents in pristine carbon nanotubes with Rashba spin-orbit interactions has been shown to be very sensitive to the symmetry of the tubes and the geometry of the setup. Here we analyze the role of defects on the spin quantum conductances of metallic carbon nanotubes due to an external electric field. We show that localized defects, such as adsorbed hydrogen atoms or pentagon-heptagon pairs, increase the Rashba spin-polarized current. Moreover, this enhancement takes place for energies closer to the Fermi energy as compared to the response of pristine tubes. Such increments can be even larger when several equally spaced defects are introduced into the system. We explore different arrangements of defects, showing that for certain geometries there are flips of the spin-polarized current and even transport suppression. Our results indicate that spin valve devices at the nanoscale may be achieved via defect engineering in carbon nanotubes.

  11. Erection of duct-like graphitic carbon nitride with enhanced photocatalytic activity for ACB photodegradation

    Science.gov (United States)

    Muhmood, Tahir; Xia, Mingzhu; Lei, Wu; Wang, Fengyun

    2018-02-01

    Novel duct graphitic carbon nitride (DCN) was successfully prepared using the temperature control method in a quartz tube furnace from commercially available melamine and evaluated against the photo-degradation of latent organic pollutants, acarbose (ACB). These prepared materials were characterized by UV–Vis spectroscopy, Fourier transform infrared spectra, x-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy and scanning electron microscopy. The characterization results indicated that the synthesized material was in the form of a duct-like structure and has greater adsorption capacity and photocatalytic ability as compared to traditionally synthesized graphitic carbon nitride materials. The DCN split theACB completely into many intermediates, which were depicted in the HPLC-MS spectrum for knowing the acarbose photo-degrdation pathway. The duct-like morphology of graphitic carbon nitride has improved properties, such as increasing the surface area and decelerating the e ‑/h + recombination, which increase the light absorbance ability with enhanced photoactivity.

  12. Percolation of Carbon Nanoparticles in Poly(3-Hexylthiophene Enhancing Carrier Mobility in Organic Thin Film Transistors

    Directory of Open Access Journals (Sweden)

    Chang-Hung Lee

    2014-01-01

    Full Text Available To improve the field-effect mobility of all-inkjet-printed organic thin film transistors (OTFTs, a composite material consisted of carbon nanoparticles (CNPs and poly(3-hexylthiophene (P3HT was reported by using homemade inkjet-printing system. These all-inkjet-printed composite OTFTs represented superior characteristics compared to the all-inkjet-printed pristine P3HT OTFTs. To investigate the enhancement mechanism of the blended materials, the percolation model was established and experimentally verified to illustrate the enhancement of the electrical properties with different blending concentrations. In addition, experimental results of OTFT contact resistances showed that both contact resistance and channel resistance were halved. At the same time, X-ray diffraction measurements, Fourier transform infrared spectra, ultraviolet-visible light, and photoluminescence spectra were also accomplished to clarify the material blending effects. Therefore, this study demonstrates the potential and guideline of carbon-based nanocomposite materials in all-inkjet-printed organic electronics.

  13. Microwave-assisted extraction and ultrasound-assisted extraction for recovering carotenoids from Gac peel and their effects on antioxidant capacity of the extracts.

    Science.gov (United States)

    Chuyen, Hoang V; Nguyen, Minh H; Roach, Paul D; Golding, John B; Parks, Sophie E

    2018-01-01

    The peel of Gac fruit ( Momordica cochinchinensis Spreng.) contains high levels of bioactive compounds, especially carotenoids which possess significant antioxidant capacities. However, the peel of Gac is regarded as a waste from the production of carotenoid-rich oil from Gac fruit. In this study, carotenoids of Gac peel were extracted by microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) using ethyl acetate as extraction solvent. The effect of extraction time and different levels of microwave and ultrasonic powers on the yield of total carotenoid and antioxidant capacity of the extracts were investigated. The results showed that an extraction at 120 W for 25 min and an extraction at 200 W for 80 min were the most effective for MAE and UAE of the Gac peel samples, respectively. The maximum carotenoid and antioxidant capacity yields of UAE were significantly higher than those of the MAE. The antioxidant capacity of extract obtained by the UAE was also significantly higher that of the conventional extraction using the same ratio of solvent to material. The results showed that both MAE and UAE could be used to reduce the extraction time significantly in comparison with conventional extraction of Gac peel while still obtained good extraction efficiencies. Thus, MAE and UAE are recommended for the improvement of carotenoid and antioxidant capacity extraction from Gac peel.

  14. Pyrrolidone Modifying Gold Nanocatalysts for Enhanced Catalytic Activities in Aerobic Oxidation of Alcohols and Carbon Monoxide

    Directory of Open Access Journals (Sweden)

    Yingji Song

    2017-01-01

    Full Text Available Enhancing the catalytic activity of supported metal nanoparticle is a great demand but extremely challenging to make. We reported a simple strategy for enhancing the activities by employing the polyvinylpyrrolidone (PVP additive, where a series of supported Au nanoparticle catalysts including Au/C, Au/BN, Au/TiO2, and Au/SBA-15 exhibited significantly higher activities in the oxidation of various alcohols and carbon monoxide by molecular oxygen after adding PVP to the reaction system. The XPS study indicates that PVP could electronically interact with Au to form high active Au sites for molecular oxygen, thus causing improved activities for the various oxidation reactions.

  15. Index assignment of a carbon nanotube rope using tip-enhanced Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Goss, Karin; Schneider, Claus M.; Meyer, Carola [Peter Gruenberg Institut, Forschungszentrum Juelich and JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany); Peica, Niculina; Thomsen, Christian; Maultzsch, Janina [Institut fuer Festkoerperphysik, Technische Universitaet Berlin, Hardenberg Str. 36, 10623 Berlin (Germany)

    2011-11-15

    We used tip-enhanced Raman spectroscopy to study the diameter-dependent Raman modes in a contacted carbon nanotube (CNT) rope. We show that with the near-field tip enhancement a large number of nanotubes within a rope can be identified, even if the nanotube modes cannot be distinguished in the far-field signal. Several metallic and semiconducting nanotubes can be identified and assigned to nanotube families. Additionally, we provide a tentative chiral index assignment. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Carbonic Anhydrase Enhanced Carbon Capture: Kinetic Measurements and Pilot Plant Trials

    DEFF Research Database (Denmark)

    Gladis, Arne; Deslauriers, Maria Gundersen; Fosbøl, Philip Loldrup

    in concentrations from 5 to 50 wt%. Necessary mass transfer parameters such as liquid side mass transfer coefficient and solvent and enzyme reaction rates were determined in a temperature range from 298 to 328 K and benchmarked to a 30 wt% MEA solution. The study reveals that the addition of the enzyme carbonic...... the impact of temperature in relation to CA. A temperature increase resulted in lower liquid side mass transfer rate for 30 wt% MDEA and 15 wt% K2CO3 but in higher rate for 30 wt% AMP. The overall first order enzyme reaction rate (s-1) was linearly dependent on enzyme concentration for 30 wt% MDEA and 15 wt......% K2CO3 at 313 K. The derived enzymatic reaction rate constant kenz (m3 kg-1 s-1) for 15 wt% K2CO3 at 313 K was about 9 times higher than for 30 wt% MDEA and 10 times higher than for 30 wt% AMP. Temperature and concentration did not observably influence the enzymatic rate constant in the concentration...

  17. Fluoride enhances transfection activity of carbonate apatite by increasing cytoplasmic stability of plasmid DNA

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, E.H., E-mail: md.ezharul.hoque@med.monash.edu.my [Jeffrey Cheah School of Medicine and Health Sciences, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, Selangor Darul Ehsan (Malaysia)

    2011-06-17

    Highlights: {yields} Cytoplasmic stability of plasmid DNA is enhanced by fluoride incorporation into carbonate apatite carrier. {yields} Fluoridated carbonate apatite promotes a robust increase in transgene expression. {yields} Controlled dissolution of fluoridated carbonate apatite in endosomal acidic environment might buffer the endosomes and prevent degradation of the released DNA. -- Abstract: Intracellular delivery of a functional gene or a nucleic acid sequence to specifically knockdown a harmful gene is a potential approach to precisely treat a critical human disease. The intensive efforts in the last few decades led to the development of a number of viral and non-viral synthetic vectors. However, an ideal delivery tool in terms of the safety and efficacy has yet to be established. Recently, we have developed pH-sensing inorganic nanocrystals of carbonate apatite for efficient and cell-targeted delivery of gene and gene-silencing RNA. Here we show that addition of very low level of fluoride to the particle-forming medium facilitates a robust increase in transgene expression following post-incubation of the particles with HeLa cells. Confocal microscopic observation and Southern blotting prove the cytoplasmic existence of plasmid DNA delivered by likely formed fluoridated carbonate apatite particles while degradation of plasmid DNA presumably by cytoplasmic nucleases was noticed following delivery with apatite particles alone. The beneficial role of fluoride in enhancing carbonate apatite-mediated gene expression might be due to the buffering potential of generated fluoridated apatite in endosomal acidic environment, thereby increasing the half-life of delivered plasmid DNA.

  18. Polypyrrole-Grafted Coconut Shell Biological Carbon as a Potential Adsorbent for Methyl Tert-Butyl Ether Removal: Characterization and Adsorption Capability

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2017-01-01

    Full Text Available Methyl tert-butyl ether (MTBE has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC. A polypyrrole (PPy-modified GAC composite (PPy/GAC was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR and Brunauer-Emmett-Teller (BET surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation, the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration <20 μg/L. Pseudomonas aeruginosa and Acinetobacter pittii may be the predominant bacteria responsible for MTBE degradation in these biofilm reactors.

  19. Polypyrrole-Grafted Coconut Shell Biological Carbon as a Potential Adsorbent for Methyl Tert-Butyl Ether Removal: Characterization and Adsorption Capability.

    Science.gov (United States)

    Li, Shanshan; Qian, Keke; Wang, Shan; Liang, Kaiqiang; Yan, Wei

    2017-01-24

    Methyl tert-butyl ether (MTBE) has been used as a common gasoline additive worldwide since the late twentieth century, and it has become the most frequently detected groundwater pollutant in many countries. This study aimed to synthesize a novel microbial carrier to improve its adsorptive capacity for MTBE and biofilm formation, compared to the traditional granular activated carbon (GAC). A polypyrrole (PPy)-modified GAC composite (PPy/GAC) was synthesized, and characterized by Fourier transform infrared spectroscopy (FT-IR) and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption behaviors of MTBE were well described by the pseudo-second-order and Langmuir isotherm models. Furthermore, three biofilm reactors were established with PPy/GAC, PPy, and GAC as the carriers, respectively, and the degradation of MTBE under continuous flow was investigated. Compared to the biofilm reactors with PPy or GAC (which both broke after a period of operation), the PPy/GAC biofilm column produced stable effluents under variable treatment conditions with a long-term effluent MTBE concentration MTBE degradation in these biofilm reactors.

  20. REMOVAL OF AN ACID DYE FROM AQUEOUS SOLUTIONS BY ADSORPTION ON A COMMERCIAL GRANULAR ACTIVATED CARBON: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDY

    Directory of Open Access Journals (Sweden)

    Marius Sebastian Secula

    2011-12-01

    Full Text Available The present paper approaches the study of the adsorption of an acid dye on a commercial granular activated carbon (GAC. Batch experiments were conducted to study the equilibrium isotherms and kinetics of Indigo Carmine on GAC. The kinetic data were analyzed using the Lagargren, Ho, Elovich, Weber-Morris and Bangham models in order to establish the most adequate model that describes this process, and to investigate the rate of IC adsorption. Equilibrium data were fitted to Langmuir and Freundlich isotherms. Langmuir isotherm equilibrium model and Ho kinetic model fitted best the experimental data.The effects of temperature (25 – 45 °C, initial concentration of dye (7.5 – 150 mg•L−1, GAC dose (0.02 – 1 g•L-1, particle size (2 – 7 mm in diameter, solution pH (3 – 11 on GAC adsorption capacity were established. The adsorption process is found to be favored by a neutral pH, high values of temperature and small particle sizes. The highest adsorption capacity (133.8 mg•g-1 of the GAC is obtained at 45 °C. The removal efficiency increases with GAC dose at relatively low initial concentrations of dye. Thermodynamic parameters such as standard enthalpy (H, standard entropy (S and standard free energy (G were evaluated. The adsorption of Indigo Carmine onto GAC is an endothermic process.

  1. Differential shrinkage induced formation of yolk-shell carbon microspheres toward enhanced microwave absorption

    Science.gov (United States)

    Tian, Chunhua; Du, Yunchen; Xu, Haiyan; Xue, Jianlei; Chu, Wenlei; Qiang, Rong; Han, Xijiang; Xu, Ping

    2017-09-01

    Rational design of the microstructure paves new ways for microwave absorbing materials because it can create more facilities for the attenuation of incident electromagnetic waves. In this study, a simple method is proposed to prepare yolk-shell carbon microspheres through differential shrinkage in the internal cores and external shells of polypyrrole microspheres with the assistance of outermost SiO2 coating. This method simplifies the preparation procedures and avoids strictly controlled conditions. The electromagnetic parameters, such as relative complex permittivity and permeability, of the as-prepared yolk-shell carbon microspheres, are investigated in the frequency range of 2.0-18.0 GHz. Compared with solid carbon microspheres, yolk-shell carbon microspheres exhibit significantly enhanced microwave absorption properties in terms of both the reflection loss intensity and absorption bandwidth. The minimum reflection loss value can reach up to -27.5 dB at 8.32 GHz with an absorber thickness of 2.96 mm. The absorption bandwidth over -10.0 dB is in the range of 11.3-16.2 GHz at the typical thickness of 2.0 mm. The enhanced microwave absorption properties may be attributed to the good attenuation ability and well matched characteristic impedance. This work not only provides a promising candidate for microwave absorption, but also provides an attractive strategy to prepare various yolk-shell composites.

  2. Karat, pulque, and gac: three shining stars in the traditional food galaxy.

    Science.gov (United States)

    Kuhnlein, Harriet V

    2004-11-01

    Karat banana, pulque prepared from Agave species, and gac fruit are three traditional local food items recently studied intensively for their nutrition potential among traditional and indigenous peoples, and are examples of how local food-based strategies can be used to ensure micronutrient nutrition. Successful health promotion and intervention programs emphasizing traditional food systems are few in the international literature, but offer promise in understanding the potential of food-based strategies. Traditional food strategies could be used not only for alleviating malnutrition, but also for developing locally relevant programs for stemming the nutrition transition and preventing chronic disease, particularly among indigenous and traditional peoples who retain knowledge of using food species in their local ecosystems.

  3. Neutron diffraction study of the magnetic-field-induced transition in Mn3GaC

    Science.gov (United States)

    Ćakιr, Ö.; Acet, M.; Farle, M.; Senyshyn, A.

    2014-01-01

    The antiperovskite Mn3GaC undergoes an isostructural cubic-cubic first order transition from a low-temperature, large-cell-volume antiferromagnetic state to a high-temperature, small-cell-volume ferromagnetic state at around 160 K. The transition can also be induced by applying a magnetic field. We study here the isothermal magnetic-field-evolution of the transition as ferromagnetism is stabilized at the expense of antiferromagnetism. We make use of the presence of the two distinct cell volumes of the two magnetic states as a probe to observe by neutron diffraction the evolution of the transition, as the external magnetic field carries the system from the antiferromagnetic to the ferromagnetic state. We show that the large-volume antiferromagnetic and the small-volume ferromagnetic states coexist in the temperature range of the transition. The ferromagnetic state is progressively stabilized as the field increases.

  4. Simulation study of dose enhancement in a cell due to nearby carbon and oxygen in particle radiotherapy

    Science.gov (United States)

    Shin, Jae Ik; Cho, Ilsung; Cho, Sungho; Kim, Eun Ho; Song, Yongkeun; Jung, Won-Gyun; Yoo, SeungHoon; Shin, Dongho; Lee, Se Byeong; Yoon, Myonggeun; Incerti, S.´ebastian; Geso, Moshi; Rosenfeld, Anatoly B.

    2015-07-01

    The aim of this study is to investigate the dose-deposition enhancement due to alpha-particle irradiation in a cellular model by using the carbon and the oxygen chemical compositions. A simulation study was performed to study dose enhancement due to carbon and oxygen for a human cell where the Geant4 code used for alpha-particle irradiation of a cellular phantom. The characteristics of the dose enhancements based on the concentrations of carbon and oxygen in the nucleus and cytoplasm by the alpha-particle radiation was investigated and was compared with those obtained by gold and gadolinium. The results showed that both the carbon- and the oxygen-induced dose enhancements were more effective than those of gold and gadolinium. We found that the dose enhancement effect was more dominant in the nucleus than in the cytoplasm if the carbon or the oxygen were uniformly distributed in the whole cell. For the condition that the added chemical composition was inserted only into the cytoplasm, the effect of the dose enhancement in the nucleus was weak. We showed that high-stopping-power materials offer a more effective dose enhancement efficacy and suggest that carbon nanotubes and oxygenation are promising candidates for dose enhancement tools in particle therapy.

  5. Progress Towards a Global Understanding of Plankton Dynamics: The Global Alliance of CPR Surveys (GACS)

    Science.gov (United States)

    Batten, S.; Richardson, A.; Melrose, C.; Muxagata, E.; Hosie, G.; Verheye, H.; Hall, J.; Edwards, M.; Koubbi, P.; Abu-Alhaija, R.; Chiba, S.; Wilson, W.; Nagappa, R.; Takahashi, K.

    2016-02-01

    The Continuous Plankton Recorder (CPR) was first used in 1931 to routinely sample plankton and its continued deployment now sustains the longest-running, and spatially most extensive marine biological sampling programme in the world. Towed behind, for the most part commercial, ships it collects plankton samples from the surface waters that are subsequently analysed to provide taxonomically-resolved abundance data on a broad range of planktonic organisms from the size of coccolithophores to euphausiids. Plankton appear to integrate changes in the physical environment and by underpinning most marine food-webs, pass on this variability to higher trophic levels which have societal value. CPRs are deployed increasingly around the globe in discrete regional surveys that until recently interacted in an informal way. In 2011 the Global Alliance of CPR Surveys (GACS) was launched to bring these surveys together to collaborate more productively and address issues such as: methodological standardization, data integration, capacity building, and data analysis. Early products include a combined global database and regularly-released global marine ecological status reports. There are, of course, limitations to the exploitation of CPR data as well as the current geographic coverage. A current focus of GACS is integration of the data with models to meaningfully extrapolate across time and space. In this way the output could be used to provide more robust synoptic representations of key plankton variables. Recent years have also seen the CPR used as a platform in itself with the inclusion of additional sensors and water samplers that can sample the microplankton. The archive of samples has already been used for some molecular investigations and curation of samples is maintained for future studies. Thus the CPR is a key element of any regional to global ocean observing system of biodiversity.

  6. Enhancing forest carbon sequestration in China: toward an integration of scientific and socio-economic perspectives.

    Science.gov (United States)

    Chen, J M; Thomas, S C; Yin, Y; Maclaren, V; Liu, J; Pan, J; Liu, G; Tian, Q; Zhu, Q; Pan, J-J; Shi, X; Xue, J; Kang, E

    2007-11-01

    This article serves as an introduction to this special issue, "China's Forest Carbon Sequestration", representing major results of a project sponsored by the Canadian International Development Agency and the Chinese Academy of Sciences. China occupies a pivotal position globally as a principle emitter of carbon dioxide, as host to some of the world's largest reforestation efforts, and as a key player in international negotiations aimed at reducing global greenhouse gas emission. The goals of this project are to develop remote sensing approaches for quantifying forest carbon balance in China in a transparent manner, and information and tools to support land-use decisions for enhanced carbon sequestration (CS) that are science based and economically and socially viable. The project consists of three components: (i) remote sensing and carbon modeling, (ii) forest and soil assessment, and (iii) integrated assessment of the socio-economic implications of CS via forest management. Articles included in this special issue are highlights of the results of each of these components.

  7. Fine Milling and Mechanochemical Activation of Mine Wastes for Enhanced CO2 Mineral Carbonation

    Science.gov (United States)

    Hitch, M.; Li, J.; Dipple, G. M.

    2013-12-01

    Mechanical activation is an effective method to enhancing the physical architecture of mineral grains for mineral carbonation and CO2 sequestration. The advantage of this level of comminution is the disruption of the mineral structure and increase its reactivity. This paper discusses mechanochemical activation of whole rock tailings and compares three grinding methods (stirred, planetary and vibratory mills). Physical characteristics influencing CO2 mineral carbonation were measured using gas adsorption, infrared spectroscopy (FTIR) scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravity analysis (TGA). Results to date have indicated that indeed the mechanochemical activation leads to microstructure, structural and chemical changes of mixtures during high-energy milling. Direct aqueous mineral carbonation helped guide the author to the most effective mineral preparation method. Finally, Reitvelt analysis was used for quantitative analysis of the carbonate product. It was found that the activation mode controls the physio-chemical efficacy of the mine waste particle and was responsible for the differences in carbonate conversion.

  8. Application of enhanced membrane bioreactor (eMBR) to treat dye wastewater.

    Science.gov (United States)

    Rondon, Hector; El-Cheikh, William; Boluarte, Ida Alicia Rodriguez; Chang, Chia-Yuan; Bagshaw, Steve; Farago, Leanne; Jegatheesan, Veeriah; Shu, Li

    2015-05-01

    An enhanced membrane bioreactor (eMBR) consisting of two anoxic bioreactors (ARs) followed by an aerated membrane bioreactor (AMBR), UV-unit and a granular activated carbon (GAC) filter was employed to treat 50-100 mg/L of remazol blue BR dye. The COD of the feed was 2334 mg/L and COD:TN:TP in the feed was 119:1.87:1. A feed flow rate of 5 L/d was maintained when the dye concentration was 50 mg/L; 10 L/d of return activated sludge was recirculated to each AR from the AMBR. Once the biological system is acclimatised, 95% of dye, 99% of COD, 97% of nitrogen and 73% of phosphorus were removed at a retention time of 74.4 h. When the effluent from the AMBR was drawn at a flux rate of 6.5 L/m(2)h, the trans-membrane pressure reached 40 kPa in every 10 days. AMBR effluent was passed through the UV-unit and GAC filter to remove the dye completely. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Enhanced carbon overconsumption in response to increasing temperatures during a mesocosm experiment

    Directory of Open Access Journals (Sweden)

    J. Taucher

    2012-09-01

    Full Text Available Increasing concentrations of atmospheric carbon dioxide are projected to lead to an increase in sea surface temperatures, potentially impacting marine ecosystems and biogeochemical cycling. Here we conducted an indoor mesocosm experiment with a natural plankton community taken from the Baltic Sea in summer. We induced a plankton bloom via nutrient addition and followed the dynamics of the different carbon and nitrogen pools for a period of one month at temperatures ranging from 9.5 °C to 17.5 °C, representing a range of ±4 °C relative to ambient temperature. The uptake of dissolved inorganic carbon (DIC and the net build-up of both particulate (POC and dissolved organic carbon (DOC were all enhanced at higher temperatures and almost doubled over a temperature gradient of 8 °C. Furthermore, elemental ratios of carbon and nitrogen (C : N in both particulate and dissolved organic matter increased in response to higher temperatures, both reaching very high C : N ratios of > 30 at +4 °C. Altogether, these observations suggest a pronounced increase in excess carbon fixation in response to elevated temperatures. Most of these findings are contrary to results from similar experiments conducted with plankton populations sampled in spring, revealing large uncertainties in our knowledge of temperature sensitivities of key processes in marine carbon cycling. Since a major difference to previous mesocosm experiments was the dominant phytoplankton species, we hypothesize that species composition might play an important role in the response of biogeochemical cycling to increasing temperatures.

  10. Micro-milling of spent granular activated carbon for its possible reuse as an adsorbent: Remaining capacity and characteristics.

    Science.gov (United States)

    Pan, Long; Takagi, Yuichi; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

    2017-05-01

    We milled granular activated carbons (GACs) that had been used for 0-9 years in water treatment plants and produced carbon particles with different sizes and ages: powdered activated carbons (PAC, median diameter 12-42 μm), superfine PAC (SPAC, 0.9-3.5 μm), and submicron-sized SPAC (SSPAC, 220-290 nm). The fact that SPAC produced from 1-year-old GAC and SSPAC from 2-year-old GAC removed 2-methylisoborneol (MIB) from water with an efficiency similar to that of virgin PAC after a carbon contact time of 30 min suggests that spent GAC could be reused for water treatment after being milled. This potential for reuse was created by increasing the equilibrium adsorption capacity via reduction of the carbon particle size and improving the adsorption kinetics. During long-term (>1 year) use in GAC beds, the volume of pores in the carbon, particularly pores with widths of 0.6-0.9 nm, was greatly reduced. The equilibrium adsorption capacities of the carbon for compounds with molecular sizes in this range could therefore decrease with increasing carbon age. Among these compounds, the decreases of capacities were prominent for hydrophobic compounds, including MIB. For hydrophobic compounds, however, the equilibrium adsorption capacities could be increased with decreasing carbon particle size. The iodine number, among other indices, was best correlated with the equilibrium adsorption capacity of the MIB and would be a good index to assess the remaining MIB adsorption capacity of spent carbon. Spent GAC can possibly be reused as SPAC or SSPAC if its iodine number is ≥ 600 mg/g. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Optimization of low energy sonication treatment for granular activated carbon colonizing biomass assessment.

    Science.gov (United States)

    Saccani, G; Bernasconi, M; Antonelli, M

    2014-01-01

    This study is aimed at optimizing a low energy sonication (LES) treatment for granular activated carbon (GAC)-colonizing biomass detachment and determination, evaluating detachment efficiency and the effects of ultrasound exposure on bacterial cell viability. GAC samples were collected from two filters fed with groundwater. Conventional heterotrophic plate count (HPC) and fluorescence microscopy with a double staining method were used to evaluate cell viability, comparing two LES procedures, without and with periodical bulk substitution. A 20 min LES treatment, with bulk substitution after cycles of 5 min as maximum treatment time, allowed to recover 87%/100% of attached biomass, protecting detached bacteria from ultrasound damaging effects. Observed viable cell inactivation rate was 6.5/7.9% cell/min, with membrane-compromised cell damage appearing to be even higher (11.5%/13.1% cell/min). Assessing bacterial detachment and damaging ultrasound effects, fluorescence microscopy turned out to be more sensitive compared to conventional HPC. The optimized method revealed a GAC-colonizing biomass of 9.9 x 10(7) cell/gGAC for plant 1 and 8.8 x 10(7) cell/gGAC for plant 2, 2 log lower than reported in literature. The difference between the two GAC-colonizing biomasses is higher in terms of viable cells (46.3% of total cells in plant 1 GAC-colonizing biomass compared to the 33.3% in plant 2). Studying influent water contamination through multivariate statistical analyses, apossible combined toxic and genotoxic effect of chromium VI and trichloroethylene was suggested as a reason for the lower viable cell fraction observed in plant 2 GAC-colonizing population.

  12. Enhancement of Carbon Nanotube Particle Distribution in PPS/PEEK/Carbon Nanotube Ternary Composites with Sausage-Like Structure

    Directory of Open Access Journals (Sweden)

    Lin Cao

    2016-02-01

    Full Text Available Carbon nanomaterial particles were selectively distributed in an incompatible and high-melting-temperature polymer blend interface, or in a particular phase, to obtain conductive composites. The composite products revealed poor morphology stability and mechanical performance due to processing several times. Poly(phenylene sulfide (PPS and poly(ether ether ketone (PEEK polymers with large differences of processing temperatures were selected as blend components to obtain a compatible blend. PPS/PEEK/multi-walled carbon nanotube (MWCNT ternary nanocomposites were prepared using a controlled melt blending process. The composite samples with similar sausage-like structures of PEEK, as a dispersed phase, promote MWCNT to maximize concentration distribution in the PPS continuous phase. As a result, the theoretical percolation threshold of the composite reduced to 0.347 wt %. Moreover, the conductivity of the composite remained stable even after processing several times. CNTs revealed a particular effect when distributed selectively in this kind of system: it can enhance the dispersion of phases and also provide conductivity to the blend at small CNT contents, which can provide more useful ideas for the development of high-melting-temperature and antistatic or conductive plastic materials.

  13. Thermodynamic Approach to Enhanced Dispersion and Physical Properties in a Carbon Nanotube/Polypeptide Nanocomposite

    Science.gov (United States)

    Lovell, Conrad S.; Wise, Kristopher E.; Kim, Jae-Woo; Lillehei, Peter T.; Harrison, Joycelyn S.; Park, Cheol

    2009-01-01

    A high molecular weight synthetic polypeptide has been designed which exhibits favorable interactions with single wall carbon nanotubes (SWCNTs). The enthalpic and entropic penalties of mixing between these two molecules are reduced due to the polypeptide's aromatic sidechains and helical secondary structure, respectively. These enhanced interactions result in a well dispersed SWCNT/Poly (L-Leucine-ran-L-Phenylalanine) nanocomposite with enhanced mechanical and electrical properties using only shear mixing and sonication. At 0.5 wt% loading of SWCNT filler, the nanocomposite exhibits simultaneous increases in the Young's modulus, failure strain, and toughness of 8%, 120%, and 144%, respectively. At one kHz, the same nanotube loading level also enhances the dielectric constant from 2.95 to 22.81, while increasing the conductivity by four orders of magnitude.

  14. Metformin enhances the radiosensitivity of human liver cancer cells to γ-rays and carbon ion beams.

    Science.gov (United States)

    Kim, Eun Ho; Kim, Mi-Sook; Furusawa, Yoshiya; Uzawa, Akiko; Han, Soorim; Jung, Won-Gyun; Sai, Sei

    2016-12-06

    The purpose of this study was to investigate the effect of metformin on the responses of hepatocellular carcinoma (HCC) cells to γ-rays (low-linear energy transfer (LET) radiation) and carbon-ion beams (high-LET radiation). HCC cells were pretreated with metformin and exposed to a single dose of γ-rays or carbon ion beams. Metformin treatment increased radiation-induced clonogenic cell death, DNA damage, and apoptosis. Carbon ion beams combined with metformin were more effective than carbon ion beams or γ-rays alone at inducing subG1 and decreasing G2/M arrest, reducing the expression of vimentin, enhancing phospho-AMPK expression, and suppressing phospho-mTOR and phospho-Akt. Thus, metformin effectively enhanced the therapeutic effect of radiation with a wide range of LET, in particular carbon ion beams and it may be useful for increasing the clinical efficacy of carbon ion beams.

  15. Metformin enhances the radiosensitivity of human liver cancer cells to γ–rays and carbon ion beams

    Science.gov (United States)

    Kim, Eun Ho; Kim, Mi-Sook; Furusawa, Yoshiya; Uzawa, Akiko; Han, Soorim; Jung, Won-Gyun; Sai, Sei

    2016-01-01

    The purpose of this study was to investigate the effect of metformin on the responses of hepatocellular carcinoma (HCC) cells to γ–rays (low-linear energy transfer (LET) radiation) and carbon-ion beams (high-LET radiation). HCC cells were pretreated with metformin and exposed to a single dose of γ–rays or carbon ion beams. Metformin treatment increased radiation-induced clonogenic cell death, DNA damage, and apoptosis. Carbon ion beams combined with metformin were more effective than carbon ion beams or γ-rays alone at inducing subG1 and decreasing G2/M arrest, reducing the expression of vimentin, enhancing phospho-AMPK expression, and suppressing phospho-mTOR and phospho-Akt. Thus, metformin effectively enhanced the therapeutic effect of radiation with a wide range of LET, in particular carbon ion beams and it may be useful for increasing the clinical efficacy of carbon ion beams. PMID:27802188

  16. Enhancement of photoluminescence from ZnO film by single wall carbon nanotubes.

    Science.gov (United States)

    Suh, Jooyoung; Song, Hooyoung; Kim, Eun Kyu

    2011-07-01

    Optical emissions from ZnO films were enhanced by a formation of hybrid structures with single wall carbon-nanotubes (SWCNTs). The SWCNTs were characterized by the presence of the associated fibers and islands together with many carbon nanotube structures and their average height was about ZnO films with SWCNTs were increased up to about 30 and 60% in the region of 3.3 eV (near band edge) and 2.3 eV (deep-level) bands, respectively. It was considered that the enhancement of optical emissions from ZnO might be resulted from the effects of an excitation light scattering by SWCNTs and a surface plasmon resonance between bandgap of ZnO and SWCNTs. The surface plasmon resonance mode in the ultra-violet regions is smaller than the deep-level region relatively. This result showed that the commercial ZnO/carbon nanotubes have a feasibility of application to optoelectronic device.

  17. Enhancement of nitrate removal at the sediment-water interface by carbon addition plus vertical mixing.

    Science.gov (United States)

    Chen, Xuechu; He, Shengbing; Zhang, Yueping; Huang, Xiaobo; Huang, Yingying; Chen, Danyue; Huang, Xiaochen; Tang, Jianwu

    2015-10-01

    Wetlands and ponds are frequently used to remove nitrate from effluents or runoffs. However, the efficiency of this approach is limited. Based on the assumption that introducing vertical mixing to water column plus carbon addition would benefit the diffusion across the sediment-water interface, we conducted simulation experiments to identify a method for enhancing nitrate removal. The results suggested that the sediment-water interface has a great potential for nitrate removal, and the potential can be activated after several days of acclimation. Adding additional carbon plus mixing significantly increases the nitrate removal capacity, and the removal of total nitrogen (TN) and nitrate-nitrogen (NO3(-)-N) is well fitted to a first-order reaction model. Adding Hydrilla verticillata debris as a carbon source increased nitrate removal, whereas adding Eichhornia crassipe decreased it. Adding ethanol plus mixing greatly improved the removal performance, with the removal rate of NO3(-)-N and TN reaching 15.0-16.5 g m(-2) d(-1). The feasibility of this enhancement method was further confirmed with a wetland microcosm, and the NO3(-)-N removal rate maintained at 10.0-12.0 g m(-2) d(-1) at a hydraulic loading rate of 0.5 m d(-1). Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Carbon capture and biogas enhancement by carbon dioxide enrichment of anaerobic digesters treating sewage sludge or food waste.

    Science.gov (United States)

    Bajón Fernández, Y; Soares, A; Villa, R; Vale, P; Cartmell, E

    2014-05-01

    The increasing concentration of carbon dioxide (CO2) in the atmosphere and the stringent greenhouse gases (GHG) reduction targets, require the development of CO2 sequestration technologies applicable for the waste and wastewater sector. This study addressed the reduction of CO2 emissions and enhancement of biogas production associated with CO2 enrichment of anaerobic digesters (ADs). The benefits of CO2 enrichment were examined by injecting CO2 at 0, 0.3, 0.6 and 0.9 M fractions into batch ADs treating food waste or sewage sludge. Daily specific methane (CH4) production increased 11-16% for food waste and 96-138% for sewage sludge over the first 24h. Potential CO2 reductions of 8-34% for sewage sludge and 3-11% for food waste were estimated. The capacity of ADs to utilise additional CO2 was demonstrated, which could provide a potential solution for onsite sequestration of CO2 streams while enhancing renewable energy production. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Enhanced terrestrial carbon uptake: global drivers and implications for the growth rate of atmospheric CO2.

    Science.gov (United States)

    Keenan, Trevor F.; Prentice, Colin; Canadell, Josep; Williams, Christopher; Han, Wang; Riley, William; Zhu, Qing; Koven, Charlie; Chambers, Jeff

    2017-04-01

    In this presentation we will focus on using decadal changes in the global carbon cycle to better understand how ecosystems respond to changes in CO2 concentration, temperature, and water and nutrient availability. Using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple process-based global vegetation models, we examine the causes and consequences of the long-term changes in the terrestrial carbon sink. We show that over the past century the sink has been greatly enhanced, largely due to the effect of elevated CO2 on photosynthesis dominating over warming induced increases in respiration. We also examine the relative roles of greening, water and nutrients, along with individual events such as El Nino. We show that a slowdown in the rate of warming over land since the start of the 21st century likely led to a large increase in the sink, and that this increase was sufficient to lead to a pause in the growth rate of atmospheric CO2. We also show that the recent El Nino resulted in the highest growth rate of atmospheric CO2 ever recorded. Our results provide evidence of the relative roles of CO2 fertilization and warming induced respiration in the global carbon cycle, along with an examination of the impact of climate extremes.

  20. Enhanced mitigation of para-chlorophenol using stratified activated carbon adsorption columns.

    Science.gov (United States)

    Sze, Michael Fan Fu; McKay, Gordon

    2012-03-01

    The adsorptive removal of toxic para-chlorophenol using activated carbon adsorption columns is a proven effective engineering process. This paper examined the possibility to stratify an adsorbent bed into layers, in order to enhance the adsorption process performance in terms of increased column service time and adsorbent bed saturation. Four different types of fixed-bed adsorption columns are used and compared under the same operating conditions, but with the variation of column geometry and activated carbon particle size stratification. The Type 3 column - a cylindrical column with particle stratification packing, is found to be the most efficient choice, as the extent of column service time and adsorbent bed saturation are the largest. This could eventually decrease the frequency of adsorbent replacement/regeneration and hence reduce the operating cost of the fixed-bed adsorption process. The Homogeneous Surface Diffusion Model (HSDM) was applied successfully to describe the dynamic adsorption of para-chlorophenol onto Filtrasorb 400 (F400) activated carbon in different types of columns. The Redlich-Peterson isotherm model equation, an experimentally derived external mass transfer correlation and a constant surface diffusivity are used in the HSDM. The optimised surface diffusivity of para-chlorophenol is found to be 1.20E-8 cm(2)/s, which is in good agreement with other phenolics/F400 carbon diffusing systems in literature. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Modelling the nucleosynthetic properties of carbon-enhanced metal-poor RR Lyrae stars

    Science.gov (United States)

    Stancliffe, Richard J.; Kennedy, Catherine R.; Lau, Herbert H. B.; Beers, Timothy C.

    2013-10-01

    Certain carbon-enhanced metal-poor stars likely obtained their composition via pollution from some of the earliest generations of asymptotic giant branch stars and as such provide important clues to early Universe nucleosynthesis. Recently, Kinman et al. discovered that the highly carbon- and barium-enriched metal-poor star SDSS J1707+58 is in fact an RR Lyrae pulsator. This gives us an object in a definite evolutionary state where the effects of dilution of material during the main sequence are minimized owing to the object having passed through first dredge-up. We perform detailed stellar modelling of putative progenitor systems in which we accreted material from asymptotic giant branch stars in the mass range 1-2 M⊙. We investigate how the surface abundances are affected by the inclusion of mechanisms like thermohaline mixing and gravitational settling. While we are able to find a reasonable fit to the carbon and sodium abundances of SDSS J1707+58, suggesting accretion of around 0.1 M⊙ from a 2 M⊙ companion, the strontium and barium abundances remain problematic and this object may have experienced something other than a standard s-process. We have more success in fitting the abundances of the mildly carbon-enriched, metal-poor RR Lyrae pulsator TY Gru (CS 22881-071), which we suggest received 0.1 M⊙ of material from a companion of around 1 M⊙.

  2. Enhanced Lithium-ion intercalation properties of coherent hydrous vanadium pentoxide-carbon cryogels nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Anqiang; Liu, Dawei; Zhou, Xiaoyuan; Garcia, Betzaita Betalla; Liang, Shu-quan; Liu, Jun; Cao, Guozhong

    2010-06-01

    Coherent hydrous vanadium pentoxide (V2O5•nH2O) - carbon cryogels (CCs) nanocomposites were synthesized by electrodeposition of vanadium pentoxide onto the porous carbon scaffold which was derived from resorcinol (R) and formaldehyde (F) organic hydrogels. As-fabricated nanocomposites were characterized by scanning electron microscopy (SEM), along with EDAX and nitrogen sorption isotherms which suggested vanadium pentoxide incorporated in the pores of carbon cryogels. The nanocomposites showed much improved discharge capacity and better cyclic stability as compared to hydrous vanadium pentoxide films deposited on platinum foil. The discharge capacity of the nanocomposites reached 280 mAh/g based on the mass of the vandium pentoxide at a current density of 100mA/g and it possessed good cycle stability at different discharge rate. The results demonstrated that electrochemical performances, such as specific discharge capacitance and reversibility of the composite electrode, could be greatly enhanced by the introduction of carbon cryogels (CCs) scaffold with three-dimensionally interconnected porous structure in which V2O5•nH2O homogeneously dispersed.

  3. Enhanced lithium-ion intercalation properties of coherent hydrous vanadium pentoxide-carbon cryogel nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Anqiang [Department of Materials Science and Engineering, University of Washington in Seattle, 302 Roberts Hall, Box 352120, Seattle, WA 352120 (United States); Department of Materials Science and Engineering, Central South University, Hunan 410083 (China); Liu, Dawei; Zhou, Xiaoyuan; Garcia, Betzaita Betalla.; Cao, Guozhong [Department of Materials Science and Engineering, University of Washington in Seattle, 302 Roberts Hall, Box 352120, Seattle, WA 352120 (United States); Liang, Shuquan [Department of Materials Science and Engineering, Central South University, Hunan 410083 (China); Liu, Jun [Pacific Northwest National Laboratory Richland, Washington 99352 (United States)

    2010-06-15

    Coherent hydrous vanadium pentoxide (V{sub 2}O{sub 5}.nH{sub 2}O)-carbon cryogel (CC) nanocomposites were synthesized by electrodeposition of vanadium pentoxide onto the porous carbon scaffold which was derived from resorcinol (R) and formaldehyde (F) organic hydrogels. As-fabricated nanocomposites were characterized by scanning electron microscopy (SEM), along with EDAX and nitrogen sorption isotherms which suggested vanadium pentoxide incorporated in the pores of carbon cryogels. The nanocomposites showed much improved discharge capacity and better cyclic stability as compared to hydrous vanadium pentoxide films deposited on platinum foil. The discharge capacity of the nanocomposites reached 280 mAh g{sup -1} based on the mass of the vandium pentoxide at a current density of 100 mA g{sup -1} and it possessed good cycle stability at different discharge rates. The results demonstrated that electrochemical performances, such as specific discharge capacitance and reversibility of the composite electrode, could be greatly enhanced by the introduction of carbon cryogels (CCs) scaffold with three-dimensionally interconnected porous structure in which V{sub 2}O{sub 5}.nH{sub 2}O homogeneously dispersed. (author)

  4. Reducing the chlorine dioxide demand in final disinfection of drinking water treatment plants using activated carbon.

    Science.gov (United States)

    Sorlini, Sabrina; Biasibetti, Michela; Collivignarelli, Maria Cristina; Crotti, Barbara Marianna

    2015-01-01

    Chlorine dioxide is one of the most widely employed chemicals in the disinfection process of a drinking water treatment plant (DWTP). The aim of this work was to evaluate the influence of the adsorption process with granular activated carbon (GAC) on the chlorine dioxide consumption in final oxidation/disinfection. A first series of tests was performed at the laboratory scale employing water samples collected at the outlet of the DWTP sand filter of Cremona (Italy). The adsorption process in batch conditions with seven different types of GAC was studied. A second series of tests was performed on water samples collected at the outlet of four GAC columns installed at the outlet of the DWTP sand filter. The results showed that the best chlorine dioxide demand (ClO2-D) reduction yields are equal to 60-80% and are achieved in the first 30 min after ClO2 addition, during the first 16 days of the column operation using a mineral, coal-based, mesoporous GAC. Therefore, this carbon removes organic compounds that are more rapidly reactive with ClO2. Moreover, a good correlation was found between the ClO2-D and UV absorbance at wavelength 254 nm using mineral carbons; therefore, the use of a mineral mesoporous GAC is an effective solution to control the high ClO2-D in the disinfection stage of a DWTP.

  5. Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 2. Model prediction

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.; Peldszus, S.; Huck, P.M. [University of Waterloo, Waterloo, ON (Canada). NSERC Chair in Water Treatment

    2009-03-01

    The adsorption of two representative pharmaceutically active compounds (PhACs) naproxen and carbamazepine and one endocrine disrupting compound (EDC) nonylphenol was studied in pilot-scale granular activated carbon (GAC) adsorbers using post-sedimentation (PS) water from a full-scale drinking water treatment plant. The GAC adsorbents were coal-based Calgon Filtrasorb 400 and coconut shell-based PICA CTIF TE. Acidic naproxen broke through fastest while nonylphenol was removed best, which was consistent with the degree to which fouling affected compound removals. Model predictions and experimental data were generally in good agreement for all three compounds, which demonstrated the effectiveness and robustness of the pore and surface diffusion model (PSDM) used in combination with the time-variable parameter approach for predicting removals at environmentally relevant concentrations (i.e., ng/L range). Sensitivity analyses suggested that accurate determination of film diffusion coefficients was critical for predicting breakthrough for naproxen and carbamazepine, in particular when high removals are targeted. Model simulations demonstrated that GAC carbon usage rates (CURs) for naproxen were substantially influenced by the empty bed contact time (EBCT) at the investigated conditions. Model-based comparisons between GAC CURs and minimum CURs for powdered activated carbon (PAC) applications suggested that PAC would be most appropriate for achieving 90% removal of naproxen, whereas GAC would be more suitable for nonylphenol. 25 refs., 4 figs., 1 tab.

  6. Plasmonic Enhanced Performance of an Infrared Detector Based on Carbon Nanotube Films.

    Science.gov (United States)

    Huang, Huixin; Wang, Fanglin; Liu, Yang; Wang, Sheng; Peng, Lian-Mao

    2017-04-12

    The carbon nanotube (CNT) has been proved to be a promising material in infrared detection, due to its many advantages of high mobility, strong infrared light absorption, and carrier collection efficiency. However, the absorption restriction from the single layer limits its effective utilization of incident light. In this paper, we introduce a plasmonic electrode structure in a CNT thin-film photodetector based on random deposited high-purity semiconducting CNTs, which can collect photoinduced carriers effectively and enhance light absorption at the same time. The largest enhancement of photocurrents can be achieved at 1650 nm wavelength with suitable plasmonic structure size. Especially, we further discuss the influence of plasmonic structures on the performance of devices. We demonstrate that the best performance improvement of the carbon nanotube detector with plasmonic structure can be enhanced by 13.7 times for photocurrent mode and 5.62 times for photovoltage mode compared to those devices without structure at 1650 nm resonant wavelength. At last, the plasmonic structures are applied on tandem photodetectors with nine virtual contacts, and both the photocurrent and photovoltage are increased. The application of plasmonic electrodes can improve detector performance and retain compact device structures, which shows great potential for optimizing infrared detectors based on nanomaterials.

  7. Conductivity enhancement of multiwalled carbon nanotube thin film via thermal compression method

    Science.gov (United States)

    Tsai, Wan-Lin; Wang, Kuang-Yu; Chang, Yao-Jen; Li, Yu-Ren; Yang, Po-Yu; Chen, Kuan-Neng; Cheng, Huang-Chung

    2014-08-01

    For the first time, the thermal compression method is applied to effectively enhance the electrical conductivity of carbon nanotube thin films (CNTFs). With the assistance of heat and pressure on the CNTFs, the neighbor multiwalled carbon nanotubes (CNTs) start to link with each other, and then these separated CNTs are twined into a continuous film while the compression force, duration, and temperature are quite enough for the reaction. Under the compression temperature of 400°C and the compression force of 100 N for 50 min, the sheet resistance can be reduced from 17 to 0.9 k Ω/sq for the CNTFs with a thickness of 230 nm. Moreover, the effects of compression temperature and the duration of thermal compression on the conductivity of CNTF are also discussed in this work.

  8. Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

    DEFF Research Database (Denmark)

    Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru

    2014-01-01

    The effect of carbon ion radiotherapy on hypoxic tumors has recently been questioned because of low linear energy transfer (LET) values in the spread-out Bragg peak (SOBP). The aim of this study was to investigate the role of hypoxia and local oxygenation changes (LOCs) in fractionated carbon ion...... radiotherapy. Three-dimensional tumors with hypoxic subvolumes were simulated assuming interfraction LOCs. Different fractionations were applied using a clinically relevant treatment plan with a known LET distribution. The surviving fraction was calculated, taking oxygen tension, dose and LET into account......, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER...

  9. Enhanced metal recovery through oxidation in liquid and/or supercritical carbon dioxide

    KAUST Repository

    Blanco, Mario

    2017-08-24

    Process for enhanced metal recovery from, for example, metal-containing feedstock using liquid and/or supercritical fluid carbon dioxide and a source of oxidation. The oxidation agent can be free of complexing agent. The metal-containing feedstock can be a mineral such as a refractory mineral. The mineral can be an ore with high sulfide content or an ore rich in carbonaceous material. Waste can also be used as the metal-containing feedstock. The metal-containing feedstock can be used which is not subjected to ultrafine grinding. Relatively low temperatures and pressures can be used. The metal-containing feedstock can be fed into the reactor at a temperature below the critical temperature of the carbon dioxide, and an exotherm from the oxidation reaction can provide the supercritical temperature. The oxidant can be added to the reactor at a rate to maintain isothermal conditions in the reactor. Minimal amounts of water can be used as an extractive medium.

  10. Power generation enhancement in novel microbial carbon capture cells with immobilized Chlorella vulgaris

    Science.gov (United States)

    Zhou, Minghua; He, Huanhuan; Jin, Tao; Wang, Hongyu

    2012-09-01

    With the increasing concerns for global climate change, a sustainable, efficient and renewable energy production from wastewater is imperative. In this study, a novel microbial carbon capture cell (MCC), is constructed for the first time by the introduction of immobilized microalgae (Chlorella vulgaris) into the cathode chamber of microbial fuel cells (MFCs) to fulfill the zero discharge of carbon dioxide. This process can achieve an 84.8% COD removal, and simultaneously the maximum power density can reach 2485.35 mW m-3 at a current density of 7.9 A m-3 and the Coulombic efficiency is 9.40%, which are 88% and 57.7% greater than that with suspended C. vulgaris, respectively. These enhancements in performance demonstrate the feasibility of an economical and effective approach for the simultaneous wastewater treatment, electricity generation and biodiesel production from microalgae.

  11. Low Evapotranspiration Enhances the Resilience of Peatland Carbon Stocks to Fire

    Science.gov (United States)

    Kettridge, N.; Lukenbach, M. C.; Hokanson, K. J.; Hopkinson, C.; Devito, K. J.; Petrone, R. M.; Mendoza, C. A.; Waddington, J. M.

    2017-09-01

    Boreal peatlands may be vulnerable to projected changes in the wildfire regime under future climates. Extreme drying during the sensitive postfire period may exceed peatland ecohydrological resilience, triggering long-term degradation of these globally significant carbon stocks. Despite these concerns, we show low peatland evapotranspiration at both the plot- and landscape-scale postfire, in water-limited peatlands dominated by feather moss that are ubiquitous across continental western Canada. Low postfire evapotranspiration enhances the resilience of carbon stocks in such peatlands to wildfire disturbance and reinforces their function as a regional source of water. Near-surface water repellency may provide an important, previously unexplored, regulator of peatland evapotranspiration that can induce low evapotranspiration in the initial postfire years by restricting the supply of water to the peat surface.

  12. Pesticide Removal by Combined Ozonation and Granular Activated Carbon Filtration

    NARCIS (Netherlands)

    Orlandini, E.

    1999-01-01

    This research aimed to idendfy and understand mechanisms that underlie the beneficial effect of ozonation on removal of pesdcides and other micropoUutants by Granular Activated Carbon (GAC) filtradon. This allows optimization of the combination of these two processes, termed Biological Activated

  13. Easy synthesis of porous carbon mesospheres and its functionalization with titania nanoparticles for enhanced field emission and photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Dheeraj [Thin Film and NanoScience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India); Banerjee, Diptonil [School of Material Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India); Sarkar, Sourav [Thin Film and NanoScience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India); Das, Nirmalya S. [School of Material Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India); Chattopadhyay, Kalyan K., E-mail: kalyan_chattopadhyay@yahoo.com [Thin Film and NanoScience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India); School of Material Science and Nanotechnology, Jadavpur University, Kolkata 700032 (India)

    2016-06-01

    A simple low temperature chemical approach for synthesizing porous carbon microspheres and its hybrid structure with titanium dioxide (TiO{sub 2}) nanoparticle is reported. The carbon spheres and related hybrid structures were characterized by X-ray diffraction, scanning and transmission electron microscopy, Raman and UV–Vis–NIR spectroscopy. The microscopic studies confirm the successful synthesis of hybrid structure of carbon spheres with TiO{sub 2} nanoparticles. Also it reveals that the porous carbon spheres were actually composed of few layers thick carbon flakes. The performance of these as-synthesized pure and hybrid materials on removal of poisonous dyes from water under photon irradiation was studied. It is found that the hybrid sample shows better photocatalytic activity. It is also shown that TiO{sub 2} nanoparticle functionalization enhances the electron field emission properties of carbon sample with reduction of turn-on field from 5.1 to 3.4 V/μm. The enhancement in the photocatalytic activity is due to the combined effect of higher surface area and the injection of electrons from carbon to TiO{sub 2} nanoparticles whereas in case of field emission TiO{sub 2} particles act as additional sites with lower work function and increase the roughness helping enhancement of field strength giving enhanced emission. - Highlights: • Carbon microspheres made of carbon sheet were synthesized by chemical route. • The as synthesized carbon structure has been functionalized with TiO{sub 2} particles. • Hybrid samples show enhanced photocatalytic activity compared to pure sample. • Hybrid sample shows better field emission for an optimized amount of TiO{sub 2} particle.

  14. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    Science.gov (United States)

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Comparative Study between Acoustic Emission Analysis and Immersion Bubble-Metric Technique, TGA and TD-GC/MS in View of the Characterization of Granular Activated Carbons Used in Rum Production

    Directory of Open Access Journals (Sweden)

    Harold Crespo Sariol

    2017-02-01

    Full Text Available Microscopic and acoustic emission analysis and sound patterns recognition techniques were applied for the characterization of granular activated carbon (GAC. A new and improved methodology has been developed to characterize the exhaustion degree of GAC used in rum production: (1 based on the acoustic emission analysis of the sound produced by water flooded on GAC; and (2 based on the microscopic analysis of bubbles formed by immersion into glycerol. Acoustic measurements are made in a specific set-up, bubble detection and analysis is performed using dedicated software developed in MATLAB® for circular shape pattern detection based on the Hough transform. Both have been correlated with data of GAC characteristics based on thermogravimetric analysis (TGA and Thermal Desorption-Gas Chromatography Mass Spectrometry (TD-GC/MS. Eight samples of GAC used in the rum production, obtained at different depths within the fixed-bed filter, have been evaluated. Good correlations are found between the immersion “bubble-metric” technique and the acoustic measurement data from the original signal processed by Band-Pass (BP filtering at 1.3 kHz and weight loss amounts of adsorbed compounds on the GAC. The found relationship gives the possibility to determine the exhaustion degree of GAC applying these methods and to evaluate high-porosity materials.

  16. Plasmon mediated enhancement and tuning of optical emission properties of two dimensional graphitic carbon nitride nanosheets

    Science.gov (United States)

    Bayan, Sayan; Gogurla, Narendar; Midya, Anupam; Singha, Achintya; Ray, Samit K.

    2017-12-01

    We demonstrate surface plasmon induced enhancement and tunablilty in optical emission properties of two dimensional graphitic carbon nitride (g-C3N4) nanosheets through the attachment of gold (Au) nanoparticles. Raman spectroscopy has revealed surface enhanced Raman scattering that arises due to the combined effect of the charge transfer process and localized surface plasmon induced enhancement in electromagnetic field, both occurring at the nanoparticle–nanosheet interface. Photoluminescence studies suggest that at an optimal concentration of nanoparticles, the emission intensity can be enhanced, which is maximum within the 500–525 nm region. Further, the fabricated electroluminescent devices reveal that the emission feature can be tuned from bluish-green to red (∼160 nm shift) upon attaching Au nanoparticles. We propose that the π*→π transition in g-C3N4 can trigger surface plasmon oscillation in Au, which subsequently increases the excitation process in the nanosheets and results in enhanced emission in the green region of the photoluminescence spectrum. On the other hand, electroluminescence of g-C3N4 can induce plasmon oscillation more efficiently and thus can lead to red emission from Au nanoparticles through the radiative damping of particle plasmons. The influence of nanoparticle size and coverage on the emission properties of two dimensional g-C3N4, nanosheets has also been studied in detail.

  17. Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon

    Directory of Open Access Journals (Sweden)

    D. A. Lack

    2010-05-01

    Full Text Available The presence of clear coatings on atmospheric black carbon (BC particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate that the enhancement of light absorption (EAbs by atmospheric black carbon (BC when it is coated in mildly absorbing material (CBrown is reduced relative to the enhancement induced by non-absorbing coatings (CClear. This reduction, sensitive to both the CBrown coating thickness and imaginary refractive index (RI, can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of CClear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with CBrown is shown to be important to the calculated single scatter albedo only when models treat BC as large spherical cores (>50 nm. For smaller BC cores (or fractal agglomerates consideration of the BC and CBrown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It has often been assumed that observation of an absorption Angström exponent (AAE>1 indicates absorption by a non-BC aerosol. Here, it is shown that BC cores coated in CClear can reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to CBrown within ambient particles. However, an AAE<1.6 does not exclude the possibility of CBrown; rather CBrown cannot be confidently assigned unless AAE>1.6. Comparison of these model

  18. New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-Doped Carbon Nanospaces

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Peter [University of Missouri; Wexler, Carlos [University of Missouri; Hawthorne, M. Frederick [University of Missouri; Lee, Mark W. [University of Missouri; Jalistegi, Satish S. [University of Missouri

    2014-08-14

    This project, since its start in 2007—entitled “Networks of boron-doped carbon nanopores for low-pressure reversible hydrogen storage” (2007-10) and “New pathways and metrics for enhanced, reversible hydrogen storage in boron-doped carbon nanospaces” (2010-13)—is in support of the DOE's National Hydrogen Storage Project, as part of the DOE Hydrogen and Fuel Cells Program’s comprehensive efforts to enable the widespread commercialization of hydrogen and fuel cell technologies in diverse sectors of the economy. Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on board a wide range of vehicle platforms, at energy densities comparable to gasoline, without compromising passenger or cargo space, remains an outstanding technical challenge. Of the main three thrust areas in 2007—metal hydrides, chemical hydrogen storage, and sorption-based hydrogen storage—sorption-based storage, i.e., storage of molecular hydrogen by adsorption on high-surface-area materials (carbons, metal-organic frameworks, and other porous organic networks), has emerged as the most promising path toward achieving the 2017 DOE storage targets of 0.055 kg H2/kg system (“5.5 wt%”) and 0.040 kg H2/liter system. The objective of the project is to develop high-surface-area carbon materials that are boron-doped by incorporation of boron into the carbon lattice at the outset, i.e., during the synthesis of the material. The rationale for boron-doping is the prediction that boron atoms in carbon will raise the binding energy of hydro- gen from 4-5 kJ/mol on the undoped surface to 10-14 kJ/mol on a doped surface, and accordingly the hydro- gen storage capacity of the material. The mechanism for the increase in binding energy is electron donation from H2 to electron-deficient B atoms, in the form of sp2 boron-carbon bonds. Our team is proud to have

  19. Carbon dots with aggregation induced emission enhancement for visual permittivity detection.

    Science.gov (United States)

    Liu, Ze Xi; Wu, Zhu Lian; Gao, Ming Xuan; Liu, Hui; Huang, Cheng Zhi

    2016-02-04

    Photoluminescent carbon dots (CDs), hydrothermally prepared using tannic acid (TA), show visual aggregation induced emission enhancement (AIEE) properties at 455 nm when excited at 350 nm owing to the rotational hindering of the surface groups on CDs such as aromatic rings and phenolic hydroxyl ones, causing exponential decay between the ratio of the photoluminescence intensity in organic solvents to that in water and the permittivity of the solvent, and thus dazzling emissions of the CDs in the presence of solvents with small permittivity, tetrahydrofuran (THF), for instance, could be visually observed.

  20. Carbon nanotube dry adhesives with temperature-enhanced adhesion over a large temperature range

    OpenAIRE

    Xu, Ming; Du, Feng; Ganguli, Sabyasachi; Roy, Ajit; Dai, Liming

    2016-01-01

    Conventional adhesives show a decrease in the adhesion force with increasing temperature due to thermally induced viscoelastic thinning and/or structural decomposition. Here, we report the counter-intuitive behaviour of carbon nanotube (CNT) dry adhesives that show a temperature-enhanced adhesion strength by over six-fold up to 143?N?cm?2 (4?mm ? 4?mm), among the strongest pure CNT dry adhesives, over a temperature range from ?196 to 1,000??C. This unusual adhesion behaviour leads to temperat...

  1. Polarized surface-enhanced Raman spectroscopy of suspended carbon nanotubes by Pt-Re nanoantennas

    Science.gov (United States)

    Bäuml, Christian; Korn, Tobias; Lange, Christoph; Schüller, Christian; Strunk, Christoph; Paradiso, Nicola

    2017-07-01

    We present optical nanoantennas designed for applications that require processing temperatures larger than 800 ∘C . The antennas consist of arrays of Re/Pt bilayer strips fabricated with a lift-off-free technique on top of etched trenches. Reflectance measurements show a clear plasmonic resonance at approximately 670 nm for light polarized orthogonal to the strip axis. The functionality of the antennas is demonstrated by growing single-walled carbon nanotubes (CNTs) on top of the antenna arrays and measuring the corresponding Raman signal enhancement of selected CNTs. The results of the measurements are quantitatively discussed in light of numerical simulations which highlight the impact of the substrate.

  2. Light absorption enhancement of black carbon from urban haze in Northern China winter.

    Science.gov (United States)

    Chen, Bing; Bai, Zhe; Cui, Xinjuan; Chen, Jianmin; Andersson, August; Gustafsson, Örjan

    2017-02-01

    Atmospheric black carbon (BC) is an important pollutant for both air quality and Earth's energy balance. Estimates of BC climate forcing remain highly uncertain, e.g., due to the mixing with non-absorbing components. Non-absorbing aerosols create a coating on BC and may thereby act as a lens which may enhance the light absorption. However, this absorption enhancement is poorly constrained. To this end a two-step solvent dissolution protocol was employed to remove both organic and inorganic coatings, and then investigate their effects on BC light absorption. Samples were collected at a severely polluted urban area, Jinan, in the North China Plain (NCP) during February 2014. The BC mass absorption cross-section (MAC) was measured for the aerosol samples before and after the solvent-decoating treatment, and the enhancement of MAC (EMAC) from the coating effect was defined as the ratio. A distinct diurnal pattern for the enhancement was observed, with EMAC 1.3 ± 0.3 (1 S.D.) in the morning, increasing to 2.2 ± 1.0 in the afternoon, after that dropping to 1.5 ± 0.8 in the evening-night. The BC absorption enhancement primarily was associated with urban-scale photochemical production of nitrate and sulfate aerosols. In addition to that, regional-scale haze plume with increasing sulfate levels strengthened the absorption enhancement. These observations offer direct evidence for an increased absorption enhancement of BC due to severe air pollution in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. [Diversity and bacteria community structure of activated carbon used in advanced drinking water treatment].

    Science.gov (United States)

    Wang, Min; Shang, Hai-tao; Hao, Chun-bo; Luo, Peng; Gu, Jun-nong

    2011-05-01

    Two granular activated carbon (GAC) samples with 1.5 a and 5 a age were collected, Bacterial genome DNA was extracted for the 16S rDNA gene amplification, and then a bacterial 16S rDNA gene clone library was constructed. After the phylogenetic analysis of 16S rDNA sequences, bacterial diversity and community structure of two activated carbon biofilm sample were studied. The results showed the bacteria in GAC with 5 a age could be divided into 11 groups, which were as follows alpha-Proteobacteria (26.5%), beta-Proteobacteria (16.3%), delta-Proteobacteria (16.3%), Planctomycetes (12.2%), Gemmatimonadetes (6.1%), Acidobacteria (4.1%), Nitrospira (2.0%), gamma-Proteobacteria (2.0%), Bacteroidetes (2.0%), Actinobacteria (2.0%), Unclassified Bacteria (10.2%). The bacteria in GAC with 1.5 a age could be divided into 10 groups, which were as follows alpha-Proteobacteria (21.6%), Planctomycetes( 10.8%), Bacteroidetes (10.8%), beta-Proteobacteria (9.0%), Acidobacteria (9.0%), Nitrospira (7.2%), detla-Proteobacteria (7.2%), Unclassified Proteobacteria (5.4%), Gemmatimonadetes (3.6%), Unclassified Bacteria (14.4%). The results revealed a variety of bacterial divisions on the studied GAC biofilm. Proteobacteria had the highest share in the two total clones, and alpha- and beta-Proteobacteria were on a dominant position. A relatively high proportion of delta-Proteobacteria was observed in the biofilm of GAC with 5 a age, and Nitrospira was in a minor proportion. However, a totally converse condition appeared in GAC with 1.5 a age. Two pathogenic bacteria, Afipia and Chryseobacterium, were detected in analyzed GACs, which implies a potential microbial risk in water supply.

  4. Enhanced Carbon Concentration in Camelina: Development of a Dedicated, High-value Biofuels Crop

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-01-01

    PETRO Project: UMass is developing an enhanced, biofuels-producing variant of Camelina, a drought-resistant, cold-tolerant oilseed crop that can be grown in many places other plants cannot. The team is working to incorporate several genetic traits into Camelina that increases its natural ability to produce oils and add the production of energy-dense terpene molecules that can be easily converted into liquid fuels. UMass is also experimenting with translating a component common in algae to Camelina that should allow the plants to absorb higher levels of carbon dioxide (CO2), which aids in enhancing photosynthesis and fuel conversion. The process will first be demonstrated in tobacco before being applied in Camelina.

  5. Radiative absorption enhancements due to the mixing state of atmospheric black carbon.

    Science.gov (United States)

    Cappa, Christopher D; Onasch, Timothy B; Massoli, Paola; Worsnop, Douglas R; Bates, Timothy S; Cross, Eben S; Davidovits, Paul; Hakala, Jani; Hayden, Katherine L; Jobson, B Tom; Kolesar, Katheryn R; Lack, Daniel A; Lerner, Brian M; Li, Shao-Meng; Mellon, Daniel; Nuaaman, Ibraheem; Olfert, Jason S; Petäjä, Tuukka; Quinn, Patricia K; Song, Chen; Subramanian, R; Williams, Eric J; Zaveri, Rahul A

    2012-08-31

    Atmospheric black carbon (BC) warms Earth's climate, and its reduction has been targeted for near-term climate change mitigation. Models that include forcing by BC assume internal mixing with non-BC aerosol components that enhance BC absorption, often by a factor of ~2; such model estimates have yet to be clearly validated through atmospheric observations. Here, direct in situ measurements of BC absorption enhancements (E(abs)) and mixing state are reported for two California regions. The observed E(abs) is small-6% on average at 532 nm-and increases weakly with photochemical aging. The E(abs) is less than predicted from observationally constrained theoretical calculations, suggesting that many climate models may overestimate warming by BC. These ambient observations stand in contrast to laboratory measurements that show substantial E(abs) for BC are possible.

  6. PH-NEUTRAL CONCRETE FOR ATTACHED MICROALGAE AND ENHANCED CARBON DIOXIDE FIXATION - PHASE I

    Energy Technology Data Exchange (ETDEWEB)

    Kerry M. Dooley; F. Carl Knopf; Robert P. Gambrell

    1999-05-31

    The novelty/innovation of the proposed work is as follows. Supercritical carbon dioxide (SC-CO {sub 2})-based extrusion and molding technology can be used to produce significantly improved (in terms of strength/unit weight, durability, hardness and chemical resistance) cement-based products. SC-CO{sub 2} can rapidly convert the calcium hydroxide in cured cement to calcium carbonate, which increases the density and unconfined compressive strength in the treated region. In cured concrete, this treated region is typically a several-mm thick layer (generally <{approx}5mm, unless treatment time is excessive). However, we have found that by treating the entire cement matrix with SC-CO{sub 2} as part of the curing process, we can carbonate it rapidly, regardless of the thickness. By ''rapidly'' we mean simultaneous carbonation/curing in < 5 ks even for large cement forms, compared to typical carbonation times of several days or even years at low pressures. Carbonation changes the pH in the treated region from {approx}13 to {approx}8, almost exactly compatible with seawater. Therefore the leaching rates from these cements is reduced. These cement improvements are directed to the development of strong but thin artificial reefs, to which can be attached microalgae used for the enhanced fixation of CO{sub 2}. It is shown below that attached microalgae, as algal beds or reefs, are more efficient for CO{sub 2} fixation by a factor of 20, compared to the open ocean on an area basis. We have performed preliminary tests of the pH-neutral cements of our invention for attachment of microalgae populations. We have found pH-neutral materials which attach microalgae readily. These include silica-enriched (pozzolanic) cements, blast-furnace slags and fly ash, which are also silica-rich. We have already developed technology to simultaneously foam, carbonate and cure the cements; this foaming process further increases cement surface areas for microalgae attachment, in

  7. CHEMICAL ANALYSIS OF A CARBON-ENHANCED VERY METAL-POOR STAR: CD-27 14351

    Energy Technology Data Exchange (ETDEWEB)

    Karinkuzhi, Drisya; Goswami, Aruna [Indian Institute of Astrophysics, Koramangala, Bangalore 560034 (India); Masseron, Thomas [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2017-01-01

    We present, for the first time, an abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high-resolution ( R  ∼ 48,000) FEROS spectrum. Our abundance analysis performed using local thermodynamic equilibrium model atmospheres shows that the object is a cool star with stellar atmospheric parameters, effective temperature T {sub eff} = 4335 K, surface gravity log g  = 0.5, microturbulence ξ  = 2.42 km s{sup −1}, and metallicity [Fe/H] = −2.6. The star exhibits high carbon and nitrogen abundances with [C/Fe] = 2.89 and [N/Fe] = 1.89. Overabundances of neutron-capture elements are evident in Ba, La, Ce, and Nd, with estimated [X/Fe] > 1, the largest enhancement being seen in Ce with [Ce/Fe] = 2.63. While the first peak s -process elements Sr and Y are found to be enhanced with respect to Fe, ([Sr/Fe] = 1.73 and [Y/Fe] = 1.91), the third peak s -process element Pb could not be detected in our spectrum at the given resolution. Europium, primarily an r -process element also shows an enhancement with [Eu/Fe] = 1.65. With [Ba/Eu] = 0.12, the object CD-27 14351 satisfies the classification criterion for a CEMP-r/s star. The elemental abundance distributions observed in this star are discussed in light of the chemical abundances observed in other CEMP stars in the literature.

  8. Enhanced photocatalytic activity of graphitic carbon nitride/carbon nanotube/Bi2WO6 ternary Z-scheme heterojunction with carbon nanotube as efficient electron mediator.

    Science.gov (United States)

    Jiang, Deli; Ma, Wanxia; Xiao, Peng; Shao, Leqiang; Li, Di; Chen, Min

    2017-10-20

    All-solid-state Z-scheme heterojunction has attracted much attention in photocatalytic field because of its strong ability in charge separation and transfer. In the present study, all-solid-state ternary Z-scheme heterojunction constructed by graphitic carbon nitride (CN) nanosheet, carbon nanotube (CNT), and Bi2WO6 (BWO) nanosheet, in which CNT was employed as the electron mediator. The CN/CNT/BWO ternary Z-scheme heterojunction shows the enhanced photocatalytic activity towards the degradation of tetracycline hydrochloride (TC) as compared to the pristine g-C3N4, Bi2WO6, CNT/BWO, CNT/CN, and CN/BWO. The significantly improved photocatalytic activity can be mainly ascribed to the formed CNT-mediated Z-scheme heterojunction, which facilitates the separation and transfer of photogenerated electron-hole pairs. Our work provides a rational design of all-solid-state Z-scheme heterojunction with CNT as the electron mediator for highly efficient photocatalysis. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. A novel electrospun nerve conduit enhanced by carbon nanotubes for peripheral nerve regeneration

    Science.gov (United States)

    Yu, Wenwen; Jiang, Xinquan; Cai, Ming; Zhao, Wen; Ye, Dongxia; Zhou, Yong; Zhu, Chao; Zhang, Xiuli; Lu, Xiaofeng; Zhang, Zhiyuan

    2014-04-01

    For artificial nerve conduits, great improvements have been achieved in mimicking the structures and components of autologous nerves. However, there are still some problems in conduit construction, especially in terms of mechanical properties, biomimetic surface tomography, electrical conductivity and sustained release of neurotrophic factors or cells. In this study, we designed and fabricated a novel electrospun nerve conduit enhanced by multi-walled carbon nanotubes (MWNTs) on the basis of a collagen/poly(ɛ-caprolactone) (collagen/PCL) fibrous scaffold. Our aim was to provide further knowledge about the mechanical effects and efficacy of MWNTs on nerve conduits as well as the biocompatibility and toxicology of MWNTs when applied in vivo. The results showed that as one component, carboxyl MWNTs could greatly alter the composite scaffold’s hydrophilicity, mechanical properties and degradability. The electrospun fibers enhanced by MWNTs could support Schwann cell adhesion and elongation as a substrate in vitro. In vivo animal studies demonstrated that the MWNT-enhanced collagen/PCL conduit could effectively promote nerve regeneration of sciatic nerve defect in rats and prevent muscle atrophy without invoking body rejection or serious chronic inflammation. All of these results showed that this MWNT-enhanced scaffold possesses good biocompatibility and MWNTs might be excellent candidates as engineered nanocarriers for further neurotrophic factor delivery research.

  10. GAC-EPA : Permanence le mardi 27 février

    CERN Multimedia

    GAC-EPA

    2018-01-01

    Le GAC organise des permanences avec entretiens individuels qui se tiennent le dernier mardi de chaque mois, sauf en juillet et décembre. La prochaine permanence se tiendra le : Mardi 27 février de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 27 mars, 24 avril, 29 mai, 26 juin, 28 août, 25 septembre, 30 octobre et 27 novembre 2018. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, au...

  11. Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction

    Science.gov (United States)

    Liu, Hui; Zhao, Qingshan; Liu, Jingyan; Ma, Xiao; Rao, Yuan; Shao, Xiaodong; Li, Zhongtao; Wu, Wenting; Ning, Hui; Wu, Mingbo

    2017-11-01

    With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm-2 at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications.

  12. Quantifying black carbon light absorption enhancement with a novel statistical approach

    Directory of Open Access Journals (Sweden)

    C. Wu

    2018-01-01

    Full Text Available Black carbon (BC particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using a 1-year measurement of mass absorption efficiency (MAE in the Pearl River Delta region (PRD. A new approach for calculating primary MAE (MAEp, the key for Eabs estimation, is demonstrated using the minimum R squared (MRS method, exploring the inherent source independency between BC and its coating materials. A unique feature of Eabs estimation with the MRS approach is its insensitivity to systematic biases in elemental carbon (EC and σabs measurements. The annual average Eabs550 is found to be 1.50 ± 0.48 (±1 SD in the PRD region, exhibiting a clear seasonal pattern with higher values in summer and lower in winter. Elevated Eabs in the summertime is likely associated with aged air masses, predominantly of marine origin, along with long-range transport of biomass-burning-influenced air masses from Southeast Asia. Core–shell Mie simulations along with measured Eabs and absorption Ångström exponent (AAE constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than in the dry season.

  13. Boron-doped, carbon-coated SnO2/graphene nanosheets for enhanced lithium storage.

    Science.gov (United States)

    Liu, Yuxin; Liu, Ping; Wu, Dongqing; Huang, Yanshan; Tang, Yanping; Su, Yuezeng; Zhang, Fan; Feng, Xinliang

    2015-03-27

    Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron-doped, carbon-coated SnO2 /graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO2/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core-shell architecture and B-doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium-ion batteries with a highly stable capacity of 1165 mA h g(-1) at 0.1 A g(-1) after 360 cycles and an excellent rate capability of 600 mA h g(-1) at 3.2 A g(-1), and thus outperforms most of the previously reported SnO2-based anode materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Polyaniline/carbon nanotube/CdS quantum dot composites with enhanced optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Mrinmoy [Department of Physics, National Institute of Technology, Durgapur, 713209 (India); Ghosh, Ranajit, E-mail: ghosh.ranajit@gmail.com [CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 (India); Maruyama, Takahiro [Department of Applied Chemistry, Meijo University, Nagoya, 4688502 (Japan); Meikap, Ajit Kumar [Department of Physics, National Institute of Technology, Durgapur, 713209 (India)

    2016-02-28

    Graphical abstract: - Highlights: • A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been synthesized via in-situ polymerization of aniline monomer. • A degree of increase in conductivity. • Size-dependent optical properties of CdS quantum dots have been observed. - Abstract: A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been developed via in-situ polymerization of aniline monomer in the presence of dispersed CdS quantum dots (size: 2.7–4.8 nm) and multi-walled carbon nanotubes (CNT), which exhibits enhanced optical and electrical properties. The existences of 1st order, 2nd order, and 3rd order longitudinal optical phonon modes, strongly indicate the high quality of synthesized CdS quantum dots. The occurrence of red shift of free exciton energy in photoluminescence is due to size dependent quantum confinement effect of CdS. The conductivity of the composites (for example PANI/CNT/CdS (2 wt.% CdS)) is increased by about 7 of magnitude compared to that of pure PANI indicating a charge transfer between CNT and polymer via CdS quantum dots. This advanced material has a great potential for high-performance of electro-optical applications.

  15. Enhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event

    Science.gov (United States)

    Bianchi, Thomas S.; Garcia-Tigreros, Fenix; Yvon-Lewis, Shari A.; Shields, Michael; Mills, Heath J.; Butman, David; Osburn, Christopher; Raymond, Peter A.; Shank, G. Christopher; DiMarco, Steven F.; Walker, Nan; Kiel Reese, Brandi; Mullins-Perry, Ruth; Quigg, Antonietta; Aiken, George R.; Grossman, Ethan L.

    2013-01-01

    Rising CO2 concentration in the atmosphere, global climate change, and the sustainability of the Earth's biosphere are great societal concerns for the 21st century. Global climate change has, in part, resulted in a higher frequency of flooding events, which allow for greater exchange between soil/plant litter and aquatic carbon pools. Here we demonstrate that the summer 2011 flood in the Mississippi River basin, caused by extreme precipitation events, resulted in a “flushing” of terrestrially derived dissolved organic carbon (TDOC) to the northern Gulf of Mexico. Data from the lower Atchafalaya and Mississippi rivers showed that the DOC flux to the northern Gulf of Mexico during this flood was significantly higher than in previous years. We also show that consumption of radiocarbon-modern TDOC by bacteria in floodwaters in the lower Atchafalaya River and along the adjacent shelf contributed to northern Gulf shelf waters changing from a net sink to a net source of CO2 to the atmosphere in June and August 2011. This work shows that enhanced flooding, which may or may not be caused by climate change, can result in rapid losses of stored carbon in soils to the atmosphere via processes in aquatic ecosystems.

  16. Enhanced Oil Recovery from Oil-wet Carbonate Rock by Spontaneous Imbibition of Aqueous Surfactant Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Standnes, Dag Chun

    2001-09-01

    The main theme of this thesis is an experimental investigation of spontaneous imbibition (SI) of aqueous cationic surfactant solution into oil-wet carbonate (chalk- and dolomite cores). The static imbibition process is believed to represent the matrix flow of oil and water in a fractured reservoir. It was known that aqueous solution of C{sub 12}-N(CH{sub 3}){sub 3}Br (C12TAB) was able to imbibe spontaneously into nearly oil-wet chalk material, but the underlying mechanism was not understood. The present work was therefore initiated, with the following objectives: (1) Put forward a hypothesis for the chemical mechanism underlying the SI of C12TAB solutions into oil-wet chalk material based on experimental data and (2) Perform screening tests of low-cost commercially available surfactants for their ability to displace oil by SI of water into oil-wet carbonate rock material. It is essential for optimal use of the surfactant in field application to have detailed knowledge about the mechanism underlying the SI process. The thesis also discusses some preliminary experimental results and suggests mechanisms for enhanced oil recovery from oil-wet carbonate rock induced by supply of thermal energy.

  17. Density control and wettability enhancement by functionalizing carbon nanotubes with nickel oxide in aluminum-carbon nanotube system.

    Science.gov (United States)

    Kim, Tae-Hoon; Park, Min-Ho; Song, Kwan-Woo; Bae, Jee-Hwan; Lee, Jae-Wook; Lee, Choong Do; Yang, Cheol-Woong

    2013-11-01

    Excellent mechanical properties of carbon nanotubes (CNTs) make them ideal reinforcements for synthesizing light weight, high strength metal matrix composite. Aluminum is attractive matrix due to its light weight and Al/CNT composites are promising materials for various industrial applications. Powder metallurgy and casting techniques are normally used for bulk fabrications of composites. Casting process which can mass-produce delicate product is more suitable than existing powder metallurgy in view point of application in industries. In CNT-metal matrix composites, however, composite bulk fabrication has been limited because of the large density gap and poor wettability between the metal and CNTs. This study suggests a method for alleviating such problems. It was found that the wettability between aluminum and CNT could be enhanced by functionalizing the CNTs with nickel oxide. This functionalization of CNTs with heavier element also reduces the density gap between the matrix and reinforcements. It is suggested that this method could possibly be used in a casting process to enable mass fabrication of CNT-metal matrix composites.

  18. Enhanced acute anti-inflammatory effects of CORM-2-loaded nanoparticles via sustained carbon monoxide delivery.

    Science.gov (United States)

    Qureshi, Omer Salman; Zeb, Alam; Akram, Muhammad; Kim, Myung-Sic; Kang, Jong-Ho; Kim, Hoo-Seong; Majid, Arshad; Han, Inbo; Chang, Sun-Young; Bae, Ok-Nam; Kim, Jin-Ki

    2016-11-01

    The aim of this study was to enhance the anti-inflammatory effects of carbon monoxide (CO) via sustained release of CO from carbon monoxide-releasing molecule-2-loaded lipid nanoparticles (CORM-2-NPs). CORM-2-NPs were prepared by hot high pressure homogenization method using trilaurin as a solid lipid core and Tween 20/Span 20/Myrj S40 as surfactant mixture. The physicochemical properties of CORM-2-NPs were characterized and CO release from CORM-2-NPs was assessed by myoglobin assay. In vitro anti-inflammatory effects were evaluated by nitric oxide assay in lipopolysaccharide-stimulated RAW 264.7 macrophages. In vivo anti-inflammatory activity was investigated by measuring paw volumes and histological examination in carrageenan-induced rat paw edema. Spherical CORM-2-NPs were around 100nm with narrow particle size distribution. The sustained CO release from CORM-2-NPs was observed and the half-life of CO release increased up to 10 times compared with CORM-2 solution. CORM-2-NPs showed enhanced in vitro anti-inflammatory effects by inhibition of nitric oxide production. Edema volume in rat paw was significantly reduced after treatment with CORM-2-NPs. Taken together, CORM-2-NPs have a great potential for CO therapeutics against inflammation via sustained release of CO. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Multiwalled carbon nanotubes enter broccoli cells enhancing growth and water uptake of plants exposed to salinity.

    Science.gov (United States)

    Martínez-Ballesta, M Carmen; Zapata, Lavinia; Chalbi, Najla; Carvajal, Micaela

    2016-06-08

    Carbon nanotubes have been shown to improve the germination and growth of some plant species, extending the applicability of the emerging nano-biotechnology field to crop science. In this work, exploitation of commercial multiwalled carbon nanotubes (MWCNTs) in control and 100 mM NaCl-treated broccoli was performed. Transmission electron microscopy demonstrated that MWCNTs can enter the cells in adult plants with higher accumulation under salt stress. Positive effect of MWCNTs on growth in NaCl-treated plants was consequence of increased water uptake, promoted by more-favourable energetic forces driving this process, and enhanced net assimilation of CO2. MWCNTs induced changes in the lipid composition, rigidity and permeability of the root plasma membranes relative to salt-stressed plants. Also, enhanced aquaporin transduction occurred, which improved water uptake and transport, alleviating the negative effects of salt stress. Our work provides new evidences about the effect of MWCNTs on plasma membrane properties of the plant cell. The positive response to MWCNTs in broccoli plants opens novel perspectives for their technological uses in new agricultural practices, especially when 1plants are exposed to saline environments.

  20. Enhancement of osteogenesis on micro/nano-topographical carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite biocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Anxiu [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Liu, Xiaochen [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Gao, Xiang; Deng, Feng [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Deng, Yi, E-mail: 18210357357@163.com [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China); Wei, Shicheng, E-mail: weishicheng99@163.com [College of Stomatology, Chongqing Medical University, Chongqing 401147 (China); Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing 401147 (China)

    2015-03-01

    As an FDA-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses excellent mechanical properties similar to those of human cortical bone and is a prime candidate to replace conventional metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. The present work aimed at developing a novel carbon fiber-reinforced polyetheretherketone–nanohydroxyapatite (PEEK/CF/n-HA) ternary biocomposite with micro/nano-topographical surface for the enhancement of the osteogenesis as a potential bioactive material for bone grafting and bone tissue-engineering applications. The combined modification of oxygen plasma and sand-blasting could improve the hydrophily and generate micro/nano-topographical structures on the surface of the CFRPEEK-based ternary biocomposite. The results clearly showcased that the micro-/nano-topographical PEEK/n-HA/CF ternary biocomposite demonstrated the outstanding ability to promote the proliferation and differentiation of MG-63 cells in vitro as well as to boost the osseointegration between implant and bone in vivo, thereby boding well application to bone tissue engineering. - Highlights: • A novel micro/nano-topographical PEEK/n-HA/CF ternary biocomposite was developed. • The modified PEEK biocomposite promotes proliferation and differentiation of cells. • In vivo osseointegration of the micro/nano-topographical PEEK/n-HA/CF was enhanced.

  1. Carbon fiber cloth supported interwoven WS{sub 2} nanosplates with highly enhanced performances for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Xiao; Chi, Jing-Qi [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Lu, Shan-Shan [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Gou, Jian-Xia [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Dong, Bin, E-mail: dongbin@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); College of Science, China University of Petroleum (East China), Qingdao 266580 (China); Li, Xiao; Liu, Yan-Ru; Yan, Kai-Li; Chai, Yong-Ming [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China); Liu, Chen-Guang, E-mail: cgliu@upc.edu.cn [State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580 (China)

    2017-01-15

    Highlights: • WS{sub 2} nanoplates supported on carbon fiber cloth (WS{sub 2}/CFC) have been synthesized. • WS{sub 2}/CFC has the good dispersion and interwoven structure of WS{sub 2}. • CFC as substrate contributes to enhanced conductivity and close combination. • WS{sub 2}/CFC exhibits ultra-high activity and stability owing to CFC as support. - Abstract: The interwoven WS{sub 2} nanoplates supported on carbon fiber cloth (WS{sub 2}/CFC) have been successfully synthesized by a facile solvothermal process. XRD and XPS confirm the formation of WS{sub 2}/CFC. SEM images show the good dispersion of WS{sub 2} nanoplates with interwoven structures on the surface of CFC. Thanks to the 3D framework of CFC, WS{sub 2} nanoplates realize overall excellent-dispersion interwoven on the surface of CFC compared with pristine bulk WS{sub 2} with severe aggregation. Moreover, CFC not only serves as excellent conductive substrate to accelerate electron transport rate, but also contributes to the close combination between WS{sub 2} and CFC for long-term stability. The electrochemical measurements show that WS{sub 2}/CFC exhibit a high specific capacitance of 399 F g{sup −1} at 1.0 A g{sup −1}, demonstrating the obviously enhanced capability compared with pristine bulk WS{sub 2}. Furthermore, WS{sub 2}/CFC realizes ultra-stable cycling stability with 99% of retention of capacitance after 500 charge-discharge cycles. It may provide novel access of designing carbon-based transition metal disulfides composites for excellent super capacitive properties.

  2. In Situ Expanding Pores of Dodecahedron-like Carbon Frameworks Derived from MOFs for Enhanced Capacitive Deionization.

    Science.gov (United States)

    Wang, Zhuo; Yan, Tingting; Shi, Liyi; Zhang, Dengsong

    2017-05-03

    The pores of dodecahedron-like carbon frameworks derived from metal-organic frameworks (MOFs) were in situ expanded via a surfactant-template strategy, which were originally demonstrated to enhance capacitive deionization (CDI). The dodecahedron-like carbon frameworks were obtained through carbonization of zeolitic imidazolate framework-8 (ZIF-8) using the cetyltrimethylammonium bromide as a supramolecular template. It is found that the dodecahedron-like carbon frameworks derived from ZIF-8 possess efficiently expanded pores while retaining the original morphology and high nitrogen contents. Compared to those of the normal ZIF-8-derived carbon, the obtained materials exhibit a hierarchically porous structure with a higher specific surface area and an improved pore volume. Electrochemical studies of the obtained electrode demonstrate that this material has a high specific capacitance and lower inner resistance. More importantly, the obtained material shows a higher salt adsorption capacity (20.05 mg/g) than the normal ZIF-8-derived carbon (13.01 mg/g). Furthermore, the obtained electrode presents a rapid salt removal rate and excellent cycling stability. The significantly enhanced deionization behavior of the obtained materials is due to the combination effect of its large accessible surface area, large pore volume, and rich nitrogen doping. The results reveal that in situ expanding pores of carbon frameworks derived from MOFs is an ideal way for constructing electrode materials with enhanced CDI performance. The present work may pave a path for the design and development of highly efficient MOF-derived electrode materials.

  3. Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control

    Science.gov (United States)

    Hagopian, John; Getty, Stephanie; Quijada, Manuel

    2012-01-01

    Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced

  4. Stimulation of the anaerobic digestion of the dry organic fraction of municipal solid waste (OFMSW) with carbon-based conductive materials.

    Science.gov (United States)

    Dang, Yan; Sun, Dezhi; Woodard, Trevor L; Wang, Li-Ying; Nevin, Kelly P; Holmes, Dawn E

    2017-08-01

    Growth of bacterial and archaeal species capable of interspecies electron exchange was stimulated by addition of conductive materials (carbon cloth or granular activated carbon (GAC)) to anaerobic digesters treating dog food (a substitute for the dry-organic fraction of municipal solid waste (OFMSW)). Methane production (772-1428mmol vs <80mmol), volatile solids removal (78%-81% vs 54%-64%) and COD removal efficiencies (∼80% vs 20%-30%) were all significantly higher in reactors amended with GAC or carbon cloth than controls. OFMSW degradation was also significantly accelerated and VFA concentrations were substantially lower in reactors amended with conductive materials. These results suggest that both conductive materials (carbon cloth and GAC) can promote conversion of OFMSW to methane even in the presence of extremely high VFA concentrations (∼500mM). Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    Science.gov (United States)

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-02-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

  6. Carbon-enhanced Metal-poor Stars in SDSS/SEGUE. I. Carbon Abundance Estimation and Frequency of CEMP Stars

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Sun [NMSU, Las Cruces; Beers, Timothy C. [Michigan State U., JINA; Masseron, Thomas [Brussels U.; Plez, Bertrand [U. Montpellier 2, LUPM; Rockosi, Constance M. [Lick Observ.; Sobeck, Jennifer [Chicago U.; Yanny, Brian [Fermilab; Lucatello, Sara [Padua Observ.; Sivarani, Thirupathi [Bangalore, Indian Inst. Astrophys.; Placco, Vinicius M. [Sao Paulo U., IAG; Carollo, Daniela [Macquarie U.

    2013-10-17

    We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the SDSS and SEGUE. By means of a star-by-star comparison with a set of SDSS/SEGUE spectra with available estimates of [C/Fe] based on published high-resolution analyses, we demonstrate that we can measure [C/Fe] from SDSS/SEGUE spectra with S/N > 15 to a precision better than 0.35 dex. Using the measured carbon-to-iron abundance ratios obtained by this technique, we derive the frequency of carbon-enhanced stars ([C/Fe] > +0.7) as a function of [Fe/H], for both the SDSS/SEGUE stars and other samples from the literature. We find that the differential frequency slowly rises from almost zero to about 14% at [Fe/H] ~ -2.4, followed by a sudden increase, by about a factor of three, to 39% from [Fe/H] ~ -2.4 to [Fe/H] ~ -3.7. We also examine how the cumulative frequency of CEMP stars varies across different luminosity classes. The giant sample exhibits a cumulative CEMP frequency of 32% for [Fe/H] < -2.5, 31% for [Fe/H] < -3.0, and 33% for [Fe/H] < -3.5. For the main-sequence turnoff stars, we obtain a lower cumulative CEMP frequency, around 10% for [Fe/H] < -2.5. The dwarf population displays a large change in the cumulative frequency for CEMP stars below [Fe/H] = -2.5, jumping from 15% for [Fe/H] < -2.5 to about 75% for [Fe/H] < -3.0. When we impose a restriction with respect to distance from the Galactic mid-plane (|Z| < 5 kpc), the frequency of the CEMP giants does not increase at low metallicity ([Fe/H] < -2.5), but rather, decreases, due to the dilution of C-rich material in stars that have undergone mixing with CNO-processed material from their interiors. The frequency of CEMP stars near the main-sequence turnoff, which are not expected to have experienced mixing, increases for [Fe/H] < -3.0. [abridged

  7. Absorption enhancement of aged black carbon aerosols affected by their microphysics: A numerical investigation

    Science.gov (United States)

    Zhang, Xiaolin; Mao, Mao; Yin, Yan; Wang, Bin

    2017-11-01

    An idealized spherical model with black carbon (BC) aggregates fully coated by sulfate is developed to study the absorption enhancement (Eab) of polydisperse BC aerosols, which is numerically calculated by the multiple-sphere T-matrix method (MSTM). The aim of this study is to evaluate the effects of aerosol microphysics on the absorption enhancement of fully coated BC particles. The Eab values of accumulation concentric coated BC aggregates with different BC fractal dimensions vary within 2%, while those of coarse coated BC aggregates can alter up to 20% depending on shell-core ratio Dp/Dc (spherical equivalent particle diameter divided by BC core diameter). The BC position inside coating can result in an Eab decrease of fully coated BC aggregates up to approximately 15% and 20% in the accumulation and coarse modes, respectively. Compared with the concentric spherical structure, the off-center coated BC aggregates shows similar Eab with a difference less than 9% in the accumulation mode, whereas it can lead to up to 31% reductions in Eab in the coarse mode. The absorption enhancement of aged BC is sensitive to particle size distribution, and it decreases as particles becomes larger in accumulation mode, whereas the reverse is true in coarse mode. For BC aggregates fully coated with a very thin layer sulfate at different size distributions, Eab values are generally in ranges of 1.5-1.8 and 1.3-1.4 in accumulation and coarse modes, respectively, while with coating reaching Dp/Dc = 2.7, their values range from 1.7-2.4 and 2.0-2.1 in accumulation and coarse modes, respectively. Our study indicates that, larger Dp/Dc with BC aggregates not close to the coating boundary, or BC position closer to particle geometric center enhance BC lensing effect, whereas BC aggregates near the boundary of heavy coating may not further enhance lensing effect significantly with increased coating fraction.

  8. Enhanced cycle stability of micro-sized Si/C anode material with low carbon content fabricated via spray drying and in situ carbonization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dingsheng; Gao, Mingxia, E-mail: gaomx@zju.edu.cn; Pan, Hongge; Liu, Yongfeng; Wang, Junhua; Li, Shouquan; Ge, Hongwei

    2014-08-01

    Highlights: • Micro-sized Si/C composites were fabricated via. spray drying and carbonization. • Multi-morphology carbon was formed in the Si/C composites. • Si/C composite with 5.6 wt.% C provides significant improved cycling stability. • Multi-morphology carbon plays effective role in improving the electrochemical property. • The method provides potential for mass production of superior Si-based anode materials. - Abstract: Micro-sized Si/C composites with in situ introduced carbon of multi-morphology were fabricated via spray drying a suspension of commercial micro-sized Si and citric acid followed by a carbonization. Different ratios of Si to citric acid were used to optimize the composition and structure of the composites and thus the electrochemical performance. Carbon flakes including crooked and flat ones were well dispersed in between the Si particles, forming Si/C composites. Floc-like carbon layers and carbon fragments were also found to cover partially the Si particles. The Si/C composite with a low carbon content of 5.6 wt.% provides an initial reversible capacity of 2700 mA h/g and a capacity of 1860 mA h/g after 60 cycles at a current density of 100 mA/g as anode material for lithium-ion batteries (LIBs), which are much higher than those of pristine Si and the Si/C composites with higher carbon content. The mechanism of the enhancement of electrochemical performance of the micro-sized Si/C composite is discussed. The fabrication method and the structure design of the composites offer valuable potential in developing adaptable Si-based anode materials for industrial applications.

  9. Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

    Directory of Open Access Journals (Sweden)

    Meng Song

    2015-09-01

    Full Text Available Integrating carbon nanotubes (CNTs and graphene into hybrid structures provides a novel approach to three dimensional (3D materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm2, and field enhancement factor of ∼1.3 × 104. The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport.

  10. Enhanced coagulation for turbidity and Total Organic Carbon (TOC) removal from river Kansawati water.

    Science.gov (United States)

    Narayan, Sumit; Goel, Sudha

    2011-01-01

    The objective of this study was to determine optimum coagulant doses for turbidity and Total Organic Carbon (TOC) removal and evaluate the extent to which TOC can be removed by enhanced coagulation. Jar tests were conducted in the laboratory to determine optimum doses of alum for the removal of turbidity and Natural Organic Matter (NOM) from river water. Various other water quality parameters were measured before and after thejar tests and included: UV Absorbance (UVA) at 254 nm, microbial concentrations, TDS, conductivity, hardness, alkalinity, and pH. The optimum alum dose for removal of turbidity and TOC was 20 mg/L for the sample collected in November 2009 and 100 mg/L for the sample collected in March 2010. In both cases, the dose for enhanced coagulation was significantly higher than that for conventional coagulation. The gain in TOC removal was insignificant compared to the increase in coagulant dose required. This is usual for low TOC (TOC need to be tested to demonstrate the effectiveness of enhanced coagulation.

  11. Carbon Nanotubes Enhance CpG Uptake and Potentiate Anti-Glioma Immunity

    Science.gov (United States)

    Zhao, Dongchang; Alizadeh, Darya; Zhang, Leying; Liu, Wei; Farrukh, Omar; Manuel, Edwin; Diamond, Don J.; Badie, Behnam

    2010-01-01

    Purpose Stimulation of toll-like receptor-9 (TLR9) by CpG oligodeoxynucleotides (CpG) has been shown to counteract the immunosuppressive microenvironment and to inhibit tumor growth in glioma models. Since TLR9 is located intracellularly, we hypothesized that methods that enhance its internalization may also potentiate its immunostimulatory response. The goal of this study was to evaluate carbon nanotubes (CNTs) as a CpG delivery vehicle in brain tumor models. Experimental Design Functionalized single-walled CNTs were conjugated with CpG (CNT-CpG) and evaluated in vitro and in mice bearing intracranial GL261 gliomas. Flow cytometry was used to assess CNT-CpG uptake and anti-glioma immune response. Tumor growth was measured by bioluminescent imaging, histology, and animal survival. Results CNT-CpG was nontoxic and enhanced CpG uptake both in vitro and intracranial gliomas. CNT-mediated CpG delivery also potentiated pro-inflammatory cytokine production by primary monocytes. Interestingly, a single intracranial injection of low-dose CNT-CpG (but not free CpG or blank CNT) eradicated intracranial GL261 gliomas in half of tumor-bearing mice. Moreover, surviving animals exhibited durable tumor-free remission (> 3 months), and were protected from intracranial tumor rechallenge, demonstrating induction of long-term anti-tumor immunity. Conclusions These findings suggest that CNTs can potentiate CpG immunopotency by enhancing its delivery into tumor-associated inflammatory cells. PMID:21088258

  12. Carbon nanotubes enhance CpG uptake and potentiate antiglioma immunity.

    Science.gov (United States)

    Zhao, Dongchang; Alizadeh, Darya; Zhang, Leying; Liu, Wei; Farrukh, Omar; Manuel, Edwin; Diamond, Don J; Badie, Behnam

    2011-02-15

    Stimulation of toll-like receptor-9 (TLR9) by CpG oligodeoxynucleotides (CpG) has been shown to counteract the immunosuppressive microenvironment and to inhibit tumor growth in glioma models. Because TLR9 is located intracellularly, we hypothesized that methods that enhance its internalization may also potentiate its immunostimulatory response. The goal of this study was to evaluate carbon nanotubes (CNT) as a CpG delivery vehicle in brain tumor models. Functionalized single-walled CNTs were conjugated with CpG (CNT-CpG) and evaluated in vitro and in mice bearing intracranial GL261 gliomas. Flow cytometry was used to assess CNT-CpG uptake and antiglioma immune response. Tumor growth was measured by bioluminescent imaging, histology, and animal survival. CNT-CpG was nontoxic and enhanced CpG uptake both in vitro and intracranial gliomas. CNT-mediated CpG delivery also potentiated proinflammatory cytokine production by primary monocytes. Interestingly, a single intracranial injection of low-dose CNT-CpG (but not free CpG or blank CNT) eradicated intracranial GL261 gliomas in half of tumor-bearing mice. Moreover, surviving animals exhibited durable tumor-free remission (>3 months), and were protected from intracranial tumor rechallenge, demonstrating induction of long-term antitumor immunity. These findings suggest that CNTs can potentiate CpG immunopotency by enhancing its delivery into tumor-associated inflammatory cells. ©2010 AACR.

  13. Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

    Science.gov (United States)

    Song, Meng; Xu, Peng; Song, Yenan; Wang, Xu; Li, Zhenhua; Shang, Xuefu; Wu, Huizhen; Zhao, Pei; Wang, Miao

    2015-09-01

    Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm2, and field enhancement factor of ˜1.3 × 104. The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport.

  14. Combined Pressure, Temperature Contrast and Surface-Enhanced Separation of Carbon Dioxide for Post-Combustion Carbon Capture

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen [Rice University; Wong, Michael [Rice University; Gupta, Mayank [Rice University; Hirasaki, George [Rice University; Cox, Kenneth [Rice University

    2016-05-01

    The Rice University research team developed a hybrid carbon dioxide (CO2) absorption process combining absorber and stripper columns using a high surface area ceramic foam gas-liquid contactor for enhanced mass transfer and utilizing waste heat for regeneration. This integrated absorber/desorber arrangement will reduce space requirements, an important factor for retrofitting existing coal-fired power plants with CO2 capture technology. Described in this report, we performed an initial analysis to estimate the technical and economic feasibility of the process. A one-dimensional (1D) CO2 absorption column was fabricated to measure the hydrodynamic and mass transfer characteristics of the ceramic foam. A bench-scale prototype was constructed to implement the complete CO2 separation process and tested to study various aspects of fluid flow in the process. A model was developed to simulate the two-dimensional (2D) fluid flow and optimize the CO2 capture process. Test results were used to develop a final technoeconomic analysis and identify the most appropriate absorbent as well as optimum operating conditions to minimize capital and operating costs. Finally, a technoeconomic study was performed to assess the feasibility of integrating the process into a 600 megawatt electric (MWe) coal-fired power plant. With process optimization, $82/MWh of COE can be achieved using our integrated absorber/desorber CO2 capture technology, which is very close to DOE's target that no more than a 35% increase in COE with CCS. An environmental, health, and safety (EH&S) assessment of the capture process indicated no significant concern in terms of EH&S effects or legislative compliance.

  15. Production of Metal-Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances.

    Science.gov (United States)

    Kim, Seung Yeon; Oh, Junghoon; Park, Sunghee; Shim, Yeonjun; Park, Sungjin

    2016-04-04

    A novel metal-free composite (GN) composed of two types of carbon-based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well-dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Microbial and Chemical Enhancement of In-Situ Carbon Mineralization in Geological Formation

    Energy Technology Data Exchange (ETDEWEB)

    Matter, J.; Chandran, K.

    2013-05-31

    Predictions of global energy usage suggest a continued increase in carbon emissions and rising concentrations of CO{sub 2} in the atmosphere unless major changes are made to the way energy is produced and used. Various carbon capture and storage (CCS) technologies are currently being developed, but unfortunately little is known regarding the fundamental characteristics of CO{sub 2}-mineral reactions to allow a viable in-situ carbon mineralization that would provide the most permanent and safe storage of geologically-injected CO{sub 2}. The ultimate goal of this research project was to develop a microbial and chemical enhancement scheme for in-situ carbon mineralization in geologic formations in order to achieve long-term stability of injected CO{sub 2}. Thermodynamic and kinetic studies of CO{sub 2}-mineral-brine systems were systematically performed to develop the in-situ mineral carbonation process that utilizes organic acids produced by a microbial reactor. The major participants in the project are three faculty members and their graduate and undergraduate students at the School of Engineering and Applied Science and at the Lamont-Doherty Earth Observatory at Columbia University: Alissa Park in Earth and Environmental Engineering & Chemical Engineering (PI), Juerg Matter in Earth and Environmental Science (Co-PI), and Kartik Chandran in Earth and Environmental Engineering (Co-PI). Two graduate students, Huangjing Zhao and Edris Taher, were trained as a part of this project as well as a number of graduate students and undergraduate students who participated part-time. Edris Taher received his MS degree in 2012 and Huangjing Zhao will defend his PhD on Jan. 15th, 2014. The interdisciplinary training provided by this project was valuable to those students who are entering into the workforce in the United States. Furthermore, the findings from this study were and will be published in referred journals to disseminate the results. The list of the papers is given at

  17. Sedimentary evidence for enhanced hydrological cycling in response to rapid carbon release during the early Toarcian oceanic anoxic event

    Science.gov (United States)

    Izumi, Kentaro; Kemp, David B.; Itamiya, Shoma; Inui, Mutsuko

    2018-01-01

    A pronounced excursion in the carbon-isotope composition of biospheric carbon and coeval seawater warming during the early Toarcian (∼183 Ma) has been linked to the large-scale transfer of 12C-enriched carbon to the oceans and atmosphere. A European bias in the distribution of available data means that the precise pattern, tempo and global expression of this carbon cycle perturbation, and the associated environmental responses, remain uncertain. Here, we present a new cm-scale terrestrial-dominated carbon-isotope record through an expanded lower Toarcian section from Japan that displays a negative excursion pattern similar to marine and terrestrial carbon-isotope records documented from Europe. These new data suggest that 12C-enriched carbon was added to the biosphere in at least one rapid, millennial-scale pulse. Sedimentological analysis indicates a close association between the carbon-isotope excursion and high-energy sediment transport and enhanced fluvial discharge. Together, these data support the hypothesis that a sudden strengthening of the global hydrological cycle occurred in direct and immediate response to rapid carbon release and atmospheric warming.

  18. Understanding the fate of organic micropollutants in sand and granular activated carbon biofiltration systems

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, L., E-mail: lidia.paredes@usc.es; Fernandez-Fontaina, E., E-mail: eduardo.fernandez.fontaina@usc.es; Lema, J.M., E-mail: juan.lema@usc.es; Omil, F., E-mail: francisco.omil@usc.es; Carballa, M., E-mail: marta.carballa@usc.es

    2016-05-01

    In this study, sand and granular activated carbon (GAC) biofilters were comparatively assessed as post-treatment technologies of secondary effluents, including the fate of 18 organic micropollutants (OMPs). To determine the contribution of adsorption and biotransformation in OMP removal, four reactors were operated (two biofilters (with biological activity) and two filters (without biological activity)). In addition, the influence of empty bed contact time (EBCT), ranging from 0.012 to 3.2 d, and type of secondary effluent (anaerobic and aerobic) were evaluated. Organic matter, ammonium and nitrate were removed in both biofilters, being their adsorption higher on GAC than on sand. According to the behaviour exhibited, OMPs were classified in three different categories: I) biotransformation and high adsorption on GAC and sand (galaxolide, tonalide, celestolide and triclosan), II) biotransformation, high adsorption on GAC but low or null adsorption on sand (ibuprofen, naproxen, fluoxetine, erythromycin, roxythromycim, sulfamethoxazole, trimethoprim, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol), and, III) only adsorption on GAC (carbamazepine, diazepam and diclofenac). No influence of EBCT (in the range tested) and type of secondary effluent was observed in GAC reactors, whereas saturation and kinetic limitation of biotransformation were observed in sand reactors. Taking into account that most of the organic micropollutants studied (around 60%) fell into category II, biotransformation is crucial for the elimination of OMPs in sand biofilters. - Highlights: • OMP removal was comparatively assessed in sand and GAC biofilters. • The contribution of adsorption and biotransformation in OMP removal was identified. • The filtering material did not affect the biological activities in biofilters. • There is no direct correlation between EBCT and OMP removal in biofilters. • The type of secondary effluent determines the lifespan of filtering

  19. Effects of activated carbon on reductive dechlorination of PCBs by organohalide respiring bacteria indigenous to sediments.

    Science.gov (United States)

    Kjellerup, B V; Naff, C; Edwards, S J; Ghosh, U; Baker, J E; Sowers, K R

    2014-04-01

    Polychlorinated biphenyls (PCBs) have accumulated in aquatic sediments due to their inherent chemical stability and their presence poses a risk due to their potential toxicity in humans and animals. Granular activated carbon (GAC) has been applied to PCB contaminated sediment sites to reduce the aqueous concentration by sequestration thus reducing the PCB exposure and toxicity to both benthic and aquatic organisms. However, it is not known how the reduction of PCB bioavailability by adsorption to GAC affects bacterial transformation of PCBs by indigenous organohalide respiring bacteria. In this study, the impact of GAC on anaerobic dechlorination by putative organohalide respiring bacteria indigenous to sediment from Baltimore Harbor was examined. It was shown that the average Cl/biphenyl after dehalogenation of Aroclor 1260 was similar between treatments with and without GAC amendment. However, GAC caused a substantial shift in the congener distribution whereby a smaller fraction of highly chlorinated congeners was more extensively dechlorinated to mono- through tri-chlorinated congeners compared to the formation of tri- through penta-chlorinated congeners in unamended sediment. The results combined with comparative sequence analysis of 16S rRNA gene sequences suggest that GAC caused a community shift to putative organohalide respiring phylotypes that coincided with more extensive dechlorination of ortho and unflanked chlorines. This shift in activity by GAC shown here for the first time has the potential to promote greater degradation in situ by promoting accumulation of less chlorinated congeners that are generally more susceptible to complete mineralization by aerobic PCB degrading bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. SST algorithms in ACSPO reanalysis of AVHRR GAC data from 2002-2013

    Science.gov (United States)

    Petrenko, B.; Ignatov, A.; Kihai, Y.; Zhou, X.; Stroup, J.

    2014-05-01

    In response to a request from the NOAA Coral Reef Watch Program, NOAA SST Team initiated reprocessing of 4 km resolution GAC data from AVHRRs flown onboard NOAA and MetOp satellites. The objective is to create a longterm Level 2 Advanced Clear-Sky Processor for Oceans (ACSPO) SST product, consistent with NOAA operations. ACSPO-Reanalysis (RAN) is used as input in the NOAA geo-polar blended Level 4 SST and potentially other Level 4 SST products. In the first stage of reprocessing (reanalysis 1, or RAN1), data from NOAA-15, -16, -17, -18, -19, and Metop-A and -B, from 2002-present have been processed with ACSPO v2.20, and matched up with quality controlled in situ data from in situ Quality Monitor (iQuam) version 1. The ~12 years time series of matchups were used to develop and explore the SST retrieval algorithms, with emphasis on minimizing spatial biases in retrieved SSTs, close reproduction of the magnitudes of true SST variations, and maximizing temporal, spatial and inter-platform stability of retrieval metrics. Two types of SST algorithms were considered: conventional SST regressions, and recently developed incremental regressions. The conventional equations were adopted in the EUMETSAT OSI-SAF formulation, which, according to our previous analyses, provide relatively small regional biases and well-balanced combination of precision and sensitivity, in its class. Incremental regression equations were specifically elaborated to automatically correct for model minus observation biases, always present when RTM simulations are employed. Improved temporal stability was achieved by recalculation of SST coefficients from matchups on a daily basis, with a +/-45 day window around the current date. This presentation describes the candidate SST algorithms considered for the next round of ACSPO reanalysis, RAN2.

  1. Enhanced performance in capacitive force sensors using carbon nanotube/polydimethylsiloxane nanocomposites with high dielectric properties

    Science.gov (United States)

    Jang, Hyeyoung; Yoon, Hyungsuk; Ko, Youngpyo; Choi, Jaeyoo; Lee, Sang-Soo; Jeon, Insu; Kim, Jong-Ho; Kim, Heesuk

    2016-03-01

    Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased dielectric properties of elastomers and simple sensor structure. We rationally design dielectric elastomers based on alkylamine modified-multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS) composites, which have a higher dielectric constant than pure PDMS. The alkylamine-MWCNTs show excellent dispersion in a PDMS matrix, thus leading to enhanced and reliable dielectric properties of the composites. A force sensor array fabricated with alkylamine-MWCNT/PDMS composites presents an enhanced response due to the higher dielectric constant of the composites than that of pure PDMS. This study is the first to report enhanced performance of capacitive force sensors by modulating the dielectric properties of elastomers. We believe that the disclosed strategy to improve the sensor performance by increasing the dielectric properties of elastomers has great potential in the development of capacitive force sensor arrays that respond to various input forces.Force sensors have attracted tremendous attention owing to their applications in various fields such as touch screens, robots, smart scales, and wearable devices. The force sensors reported so far have been mainly focused on high sensitivity based on delicate microstructured materials, resulting in low reproducibility and high fabrication cost that are limitations for wide applications. As an alternative, we demonstrate a novel capacitive-type force sensor with enhanced performance owing to the increased

  2. Enhanced terrestrial carbon uptake linked to a recent pause in the growth rate of atmospheric CO2

    Science.gov (United States)

    Keenan, T. F.; Prentice, I. C. C.; Canadell, J.; Williams, C. A.; Wang, H.; Collatz, G. J.

    2016-12-01

    The terrestrial carbon sink is increasing, yet the mechanisms responsible for its long-term enhancement, and implications for the growth rate of atmospheric CO2, remain unclear. Here, using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple process-based global vegetation models, we examine the causes and consequences of the enhancement of the terrestrial carbon sink. We show that over the past century the enhanced sink is largely due to the effect of elevated CO2 on photosynthesis dominating over warming induced increases in respiration. The slowdown in global warming since the start of the 21st century is shown to have increased the sink, leading to a pause in the growth rate of atmospheric CO2, and providing further evidence of the relative roles of CO2 fertilization and warming induced respiration. The effect of enhanced terrestrial carbon uptake on the atmospheric CO2 growth rate highlights the need to protect both existing carbon stocks and those areas where the sink is growing most rapidly.

  3. Carbon-Nanotube-Enhanced Thermal Contactor in Low Contact Pressure Region

    Science.gov (United States)

    Tsukamoto, Takashiro; Esashi, Masayoshi; Tanaka, Shuji

    2010-07-01

    We first demonstrated considerable reduction of thermal contact resistance (TCR) of a bending thermal contactor in microscale using carbon nanotubes (CNTs). TCR reduction using CNTs were previously reported with flat contact surface, but the thermal contact surfaces of actual microdevices often bend because of their residual and thermal stress. We evaluated both flat and bending contact surfaces to apply this method for a variety of applications. The TCR reduction is observed not only with a flat contact surface but also a bending surface. A bending micro thermal contactor with a plasma-enhanced chemical vapor deposition (PECVD)-grown 10 µm long “CNT carpet” shows a TCR of ca. 600 mm2 K/W at a contact pressure of 20 kPa, which is about 1/10 to the TCR of the reference contactor without “CNT carpet”. This technique is useful for micro thermal devices such as micro thermal switch.

  4. Electrochemical detection of amaranth in food based on the enhancement effect of carbon nanotube film.

    Science.gov (United States)

    Wang, Peng; Hu, Xiaozhong; Cheng, Qin; Zhao, Xiaoya; Fu, Xiaofang; Wu, Kangbing

    2010-12-08

    Amaranth is widely added to food and can cause many adverse health effects when it is excessively consumed. Therefore, the monitoring of amaranth is quite important. Herein, an electrochemical sensor for the sensitive and rapid detection of amaranth was reported using multiwall carbon nanotube (MWNT) as the sensing film. Due to the large surface area and high accumulation efficiency, the MWNT sensor showed a strong enhancement effect on the oxidation of amaranth, and greatly increased the current signal. The detection conditions such as pH value, amount of MWNT, accumulation potential and time were optimized. The linear range is from 40 nM to 0.8 μM, and the limit of detection is 35 nM. Finally, the new sensor was successfully employed to detect amaranth in soft drinks, and the results were tested by high-performance liquid chromatography.

  5. Sulfur (VI) modified graphite carbon nitride nanosheets with chrysanthemum-like structure and enhanced photocatalytic activity

    Science.gov (United States)

    Xie, Lili; Dai, Yunrong; Zhou, Yijing; Chang, Xin; Yin, Lifeng

    2018-02-01

    Chrysanthemum-like sulfur (VI) modified graphite carbon nitride (s/g-C3N4) was synthesized by sulfuring and sonicating bulk g-C3N4 at 800 kHz. The sulfuring relaxed the interlayer force of g-C3N4, and the sonication constructed its chrysanthemum-like structure which enhances the separation of photo-generated carriers and photochemical response. Density functional calculation and diffusion reflection spectra (DRS) verified that sulfur (VI) modification shifted down the valence band edge of g-C3N4 and improved the redox potentials of g-C3N4. The photocatalytic degradation efficiency of 4-nitrophenol (10 mg L-1) by s/g-C3N4 was 49.3 times higher than that by bulk g-C3N4 under visible light irradiation (>400 nm).

  6. Multiwalled carbon nanotubes-sulfur composites with enhanced electrochemical performance for lithium/sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xin Zhou; Jin, Bo, E-mail: jinbo@jlu.edu.cn; Xin, Pei Ming; Wang, Huan Huan

    2014-07-01

    Multiwalled carbon nanotubes-sulfur (MWCNTs-S) composites were synthesized by chemical activation of MWCNTs and capillarity between sulfur and MWCNTs. The MWCNTs activated by potassium hydroxide (denoted as K-MWCNTs) were used as conductive additive. The as-prepared K-MWCNTs-S composites can display excellent cycle stability and rate capability with the initial discharge capacity of 741 mAh g⁻¹ and capacity retention of 80% after 50 cycles compared to pure S. The improvement in the electrochemical performance for K-MWCNTs-S composites is attributed to the interstitial structure of the MWCNTs resulted from the strong chemical etching, which can facilitate the insertion and extraction of Li ions and more better percolation of the electrolyte, and also ascribed to enhanced electronic conductivity of K-MWCNTs-S composites. It is indicated that the K-MWCNTs-S composites can be used as the cathode materials for lithium–sulfur batteries.

  7. Retracted-Enhanced X-Ray Absorption Property of Gold-Doped Single Wall Carbon Nanotube

    Directory of Open Access Journals (Sweden)

    Alimin Alimin

    2015-11-01

    Full Text Available Enhanced X-ray absorption property of single wall carbon nanotube (SWCNT through gold (Au doping (Au@SWCNT has been studied. Mass attenuation coefficient of SWCNT increased 5.2-fold after Au doping treatment. The use of ethanol in the liquid phase adsorption could produce Au nanoparticles as confirmed by the X-ray Diffraction (XRD patterns. The possibility of gold nanoparticles encapsulated in the internal tube space of SWCNT was observed by transmission electron microscope technique. A significant decrease of nitrogen uptakes and upshifts of Radial Breathing Mode (RBM of Au@SWCNT specimen suggest that the nanoparticles might be encapsulated in the internal tube spaces of the nanotube. In addition, a decrease intensity of XRD pattern of Au@SWCNT at around 2θ ≈ 2.6° supports the suggestion that Au nanoparticles are really encapsulated into SWCNT.

  8. Mechanism of wiggling enhancement due to HBr gas addition during amorphous carbon etching

    Science.gov (United States)

    Kofuji, Naoyuki; Ishimura, Hiroaki; Kobayashi, Hitoshi; Une, Satoshi

    2015-06-01

    The effect of gas chemistry during etching of an amorphous carbon layer (ACL) on wiggling has been investigated, focusing especially on the changes in residual stress. Although the HBr gas addition reduces critical dimension loss, it enhances the surface stress and therefore increases wiggling. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the increase in surface stress was caused by hydrogenation of the ACL surface with hydrogen radicals. Three-dimensional (3D) nonlinear finite element method analysis confirmed that the increase in surface stress is large enough to cause the wiggling. These results also suggest that etching with hydrogen compound gases using an ACL mask has high potential to cause the wiggling.

  9. Enhanced Catalytic Activity of Cobalt Porphyrin in CO2 Electroreduction upon Immobilization on Carbon Materials.

    Science.gov (United States)

    Hu, Xin-Ming; Rønne, Magnus H; Pedersen, Steen U; Skrydstrup, Troels; Daasbjerg, Kim

    2017-06-01

    In a comparative study of the electrocatalytic CO2 reduction, cobalt meso-tetraphenylporphyrin (CoTPP) is used as a model molecular catalyst under both homogeneous and heterogeneous conditions. In the former case, employing N,N-dimethylformamide as solvent, CoTPP performs poorly as an electrocatalyst giving low product selectivity in a slow reaction at a high overpotential. However, upon straightforward immobilization of CoTPP onto carbon nanotubes, a remarkable enhancement of the electrocatalytic abilities is seen with CO2 becoming selectively reduced to CO (>90 %) at a low overpotential in aqueous medium. This effect is ascribed to the particular environment created by the aqueous medium at the catalytic site of the immobilized catalyst that facilitates the adsorption and further reaction of CO2 . This work highlights the significance of assessing an immobilized molecular catalyst from more than homogeneous measurements alone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Enhanced enzymatic cellulose hydrolysis by subcritical carbon dioxide pretreatment of sugarcane bagasse.

    Science.gov (United States)

    Zhang, Hongdan; Wu, Shubin

    2014-04-01

    Most biomass pretreatment processes for sugar production are run at low-solid concentration (carbon dioxide (CO2) could provide a more sustainable pretreatment medium while using relative high-solid contents (15 wt.%). The effects of subcritical CO2 pretreatment of sugarcane bagasse to the solid and glucan recoveries at different pretreatment conditions were investigated. Subsequently, enzymatic hydrolysis at different hydrolysis time was applied to obtain maximal glucose yield, which can be used for ethanol fermentation. The maximum glucose yield in enzyme hydrolyzate reached 38.5 g based on 100g raw material after 72 h of enzymatic hydrolysis, representing 93.0% glucose in sugarcane bagasse. The enhanced digestibilities of subcritical CO2 pretreated sugarcane bagasse were due to the removal of hemicellulose, which were confirmed by XRD, FTIR, SEM, and TGA analyses. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Nanosized graphene sheets enhanced photoelectric behavior of carbon film on p-silicon substrate

    Science.gov (United States)

    Yang, Lei; Hu, Gaijuan; Zhang, Dongqing; Diao, Dongfeng

    2016-07-01

    We found that nanosized graphene sheets enhanced the photoelectric behavior of graphene sheets embedded carbon (GSEC) film on p-silicon substrate, which was deposited under low energy electron irradiation in electron cyclotron resonance plasma. The GSEC/p-Si photodiode exhibited good photoelectric performance with photoresponsivity of 206 mA/W, rise and fall time of 2.2, and 4.3 μs for near-infrared (850 nm) light. The origin of the strong photoelectric behavior of GSEC film was ascribed to the appearance of graphene nanosheets, which led to higher barrier height and photoexcited electron-collection efficiency. This finding indicates that GSEC film has the potential for photoelectric applications.

  12. Carbon quantum dots coated BiVO{sub 4} inverse opals for enhanced photoelectrochemical hydrogen generation

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Feng; Shen, Mingrong; Fang, Liang, E-mail: zhkang@suda.edu.cn, E-mail: lfang@suda.edu.cn [College of Physics, Optoelectronics and Energy and Jiangsu Key Laboratory of Thin Films, Soochow University, Suzhou 215006 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn, E-mail: lfang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices, and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Wang, Junling [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2015-04-13

    Carbon quantum dots (CQDs) coated BiVO{sub 4} inverse opal (io-BiVO{sub 4}) structure that shows dramatic improvement of photoelectrochemical hydrogen generation has been fabricated using electrodeposition with a template. The io-BiVO{sub 4} maximizes photon trapping through slow light effect, while maintaining adequate surface area for effective redox reactions. CQDs are then incorporated to the io-BiVO{sub 4} to further improve the photoconversion efficiency. Due to the strong visible light absorption property of CQDs and enhanced separation of the photoexcited electrons, the CQDs coated io-BiVO{sub 4} exhibit a maximum photo-to-hydrogen conversion efficiency of 0.35%, which is 6 times higher than that of the pure BiVO{sub 4} thin films. This work is a good example of designing composite photoelectrode by combining quantum dots and photonic crystal.

  13. Green synthesis of carbon quantum dots embedded onto titanium dioxide nanowires for enhancing photocurrent

    Science.gov (United States)

    Yen, Yin-Cheng; Lin, Chia-Chi; Chen, Ping-Yu; Ko, Wen-Yin; Tien, Tzu-Rung; Lin, Kuan-Jiuh

    2017-05-01

    The green synthesis of nanowired photocatalyst composed of carbon quantum dots-titanium hybrid-semiconductors, CQDs/TiO2, are reported. Where graphite-based CQDs with a size less than 5 nm are directly synthesized in pure water electrolyte by a one-step electrochemistry approach and subsequently electrodeposited onto as-prepared TiO2 nanowires through a voltage-driven reduction process. Electron paramagnetic resonance studies show that the CQDs can generate singlet oxygen and/or oxygen radicals to decompose the kinetic H2O2 intermediate species upon UV light illumination. With the effect of peroxidase-like CQDs, photocurrent density of CQDs/TiO2 is remarkably enhanced by a 6.4 factor when compared with that of as-prepared TiO2.

  14. Carbon Nanotube Enhanced Aerospace Composite Materials A New Generation of Multifunctional Hybrid Structural Composites

    CERN Document Server

    Kostopoulos, V

    2013-01-01

    The well documented increase in the use of high performance composites as structural materials in aerospace components is continuously raising the demands in terms of dynamic performance, structural integrity, reliable life monitoring systems and adaptive actuating abilities. Current technologies address the above issues separately; material property tailoring and custom design practices aim to the enhancement of dynamic and damage tolerance characteristics, whereas life monitoring and actuation is performed with embedded sensors that may be detrimental to the structural integrity of the component. This publication explores the unique properties of carbon nanotubes (CNT) as an additive in the matrix of Fibre Reinforced Plastics (FRP), for producing structural composites with improved mechanical performance as well as sensing/actuating capabilities. The successful combination of the CNT properties and existing sensing actuating technologies leads to the realization of a multifunctional FRP structure. The curre...

  15. Grassland to shrubland state transitions enhance carbon sequestration in the northern Chihuahuan Desert.

    Science.gov (United States)

    Petrie, M D; Collins, S L; Swann, A M; Ford, P L; Litvak, M E

    2015-03-01

    The replacement of native C4 -dominated grassland by C3 -dominated shrubland is considered an ecological state transition where different ecological communities can exist under similar environmental conditions. These state transitions are occurring globally, and may be exacerbated by climate change. One consequence of the global increase in woody vegetation may be enhanced ecosystem carbon sequestration, although the responses of arid and semiarid ecosystems may be highly variable. During a drier than average period from 2007 to 2011 in the northern Chihuahuan Desert, we found established shrubland to sequester 49 g C m(-2) yr(-1) on average, while nearby native C4 grassland was a net source of 31 g C m(-2) yr(-1) over this same period. Differences in C exchange between these ecosystems were pronounced--grassland had similar productivity compared to shrubland but experienced higher C efflux via ecosystem respiration, while shrubland was a consistent C sink because of a longer growing season and lower ecosystem respiration. At daily timescales, rates of carbon exchange were more sensitive to soil moisture variation in grassland than shrubland, such that grassland had a net uptake of C when wet but lost C when dry. Thus, even under unfavorable, drier than average climate conditions, the state transition from grassland to shrubland resulted in a substantial increase in terrestrial C sequestration. These results illustrate the inherent tradeoffs in quantifying ecosystem services that result from ecological state transitions, such as shrub encroachment. In this case, the deleterious changes to ecosystem services often linked to grassland to shrubland state transitions may at least be partially offset by increased ecosystem carbon sequestration. © 2014 John Wiley & Sons Ltd.

  16. Systematic Tuning and Multifunctionalization of Covalent Organic Polymers for Enhanced Carbon Capture

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Zhonghua; Mercado, Rocio; Huck, Johanna M.; Wang, Hui; Guo, Zhanhu; Wang, Wenchuan; Cao, Dapeng; Haranczyk, Maciej; Smit, Berend

    2015-10-21

    Porous covalent polymers are attracting increasing interest in the fields of gas adsorption, gas separation, and catalysis due to their fertile synthetic polymer chemistry, large internal surface areas, and ultrahigh hydrothermal stabilities. While precisely manipulating the porosities of porous organic materials for targeted applications remains challenging, we show how a large degree of diversity can be achieved in covalent organic polymers by incorporating multiple functionalities into a single framework, as is done for crystalline porous materials. Here, we synthesized 17 novel porous covalent organic polymers (COPs) with finely tuned porosities, a wide range of Brunauer–Emmett–Teller (BET) specific surface areas of 430–3624 m2 g–1, and a broad range of pore volumes of 0.24–3.50 cm3 g–1, all achieved by tailoring the length and geometry of building blocks. Furthermore, we are the first to successfully incorporate more than three distinct functional groups into one phase for porous organic materials, which has been previously demonstrated in crystalline metal–organic frameworks (MOFs). COPs decorated with multiple functional groups in one phase can lead to enhanced properties that are not simply linear combinations of the pure component properties. For instance, in the dibromobenzene-lined frameworks, the bi- and multifunctionalized COPs exhibit selectivities for carbon dioxide over nitrogen twice as large as any of the singly functionalized COPs. These multifunctionalized frameworks also exhibit a lower parasitic energy cost for carbon capture at typical flue gas conditions than any of the singly functionalized frameworks. Despite the significant improvement, these frameworks do not yet outperform the current state-of-art technology for carbon capture. Nonetheless, the tuning strategy presented here opens up avenues for the design of novel catalysts, the synthesis of functional sensors from these materials, and the improvement in the performance

  17. Damage Tolerance Enhancement of Carbon Fiber Reinforced Polymer Composites by Nanoreinforcement of Matrix

    Science.gov (United States)

    Fenner, Joel Stewart

    and fracture morphology between the two materials, related to the differences in properties. Altogether these results provided a means for proposing an explanation of the mechanism of reinforcement (and damage tolerance enhancement) provided by carbon nanotubes in hybrid composite materials.

  18. Voids padding induced further enhancement in photocatalytic performance of porous graphene-like carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guohui [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Chen, Dong [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Luo, Jianmin [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); The Graduate School of Chinese Academy of Science, Beijing, 100049 (China); Zhu, Yunqing [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China); Zeng, Yubin, E-mail: zengyubin@whu.edu.cn [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Wang, Chuanyi, E-mail: cywang@ms.xjb.ac.cn [Hubei Key Laboratory of Accoutrement Technique in Fluid Machinery and Power Engineering, Wuhan university, Hubei 430072 (China); Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011 (China)

    2017-08-05

    Highlights: • We synthesized an NH{sub 4}Cl padded C{sub 6}N{sub 9}H{sub 3} by calcining melamine hydrochloride in a vertical pit furnace. • The padded Cl{sup −} serves as a conjugate center to increase the conjugation fidelity of C{sub 6}N{sub 9}H{sub 3}. • Interface electric field can be constructed between Cl{sup −} and NH{sub 4}{sup +} to inhibit the surface recombination of carriers. • NH{sub 4}Cl padded C{sub 6}N{sub 9}H{sub 3} exhibits enhanced photocatalytic activity in terms of NO removal and water splitting. - Abstract: Design of 2-Dimensional nanostructured photocatalyst is an effective way to improve the photocatalytic activity of its bulk counterpart. However, the remaining (or newborn) drawbacks, such as enlarged band gap and the surface recombination of photogenerated charge carries, extremely limited the practical application of nanosheeted photocatalysts in solar energy conversion. In this study, we demonstrated that the voids padding with NH{sub 4}Cl can eliminate part of quantum size effect to reduce the band gap of nanosheeted carbon nitride. In addition, the padded NH{sub 4}Cl can create conjugate center and interface electric field in nanosheeted carbon nitride, and therefore to inhibit the surface recombination of photogenerated charge carries. This work not only provides a facile strategy to eliminate the drawbacks of nanosheeted carbon nitride, but also paves a new way to further improve the photocatalytic activity of other nano-sheeted materials.

  19. Enhanced Radio Frequency Biosensor for Food Quality Detection Using Functionalized Carbon Nanofillers.

    Science.gov (United States)

    Tanguy, Nicolas R; Fiddes, Lindsey K; Yan, Ning

    2015-06-10

    This paper outlines an improved design of inexpensive, wireless and battery free biosensors for in situ monitoring of food quality. This type of device has an additional advantage of being operated remotely. To make the device, a portion of an antenna of a passive 13.56 MHz radio frequency identification (RFID) tag was altered with a sensing element composed of conductive nanofillers/particles, a binding agent, and a polymer matrix. These novel RFID tags were exposed to biogenic amine putrescine, commonly used as a marker for food spoilage, and their response was monitored over time using a general-purpose network analyzer. The effect of conductive filler properties, including conductivity and morphology, and filler functionalization was investigated by preparing sensing composites containing carbon particles (CPs), multiwall carbon nanotubes (MWCNTs), and binding agent grafted-multiwall carbon nanotubes (g-MWCNTs), respectively. During exposure to putrescine, the amount of reflected waves, frequency at resonance, and quality factor of the novel RFID tags decreased in response. The use of MWCNTs reduced tag cutoff time (i.e., faster response time) as compared with the use of CPs, which highlighted the effectiveness of the conductive nanofiller morphology, while the addition of g-MWCNTs further accelerated the sensor response time as a result of localized binding on the conductive nanofiller surface. Microstructural investigation of the film morphology indicated a better dispersion of g-MWCNTs in the sensing composite as compared to MWCNTs and CPs, as well as a smoother texture of the surface of the resulting coating. These results demonstrated that grafting of the binding agent onto the conductive particles in the sensing composite is an effective way to further enhance the detection sensitivity of the RFID tag based sensor.

  20. Abundance and diversity of ammonia-oxidizing archaea and bacteria on granular activated carbon and their fates during drinking water purification process.

    Science.gov (United States)

    Niu, Jia; Kasuga, Ikuro; Kurisu, Futoshi; Furumai, Hiroaki; Shigeeda, Takaaki; Takahashi, Kazuhiko

    2016-01-01

    Ammonia is a precursor to trichloramine, which causes an undesirable chlorinous odor. Granular activated carbon (GAC) filtration is used to biologically oxidize ammonia during drinking water purification; however, little information is available regarding the abundance and diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) associated with GAC. In addition, their sources and fates in water purification process remain unknown. In this study, six GAC samples were collected from five full-scale drinking water purification plants in Tokyo during summer and winter, and the abundance and community structure of AOA and AOB associated with GAC were studied in these two seasons. In summer, archaeal and bacterial amoA genes on GACs were present at 3.7 × 10(5)-3.9 × 10(8) gene copies/g-dry and 4.5 × 10(6)-4.2 × 10(8) gene copies/g-dry, respectively. In winter, archaeal amoA genes remained at the same level, while bacterial amoA genes decreased significantly for all GACs. No differences were observed in the community diversity of AOA and AOB from summer to winter. Phylogenetic analysis revealed high AOA diversity in group I.1a and group I.1b in raw water. Terminal-restriction fragment length polymorphism analysis of processed water samples revealed that AOA diversity decreased dramatically to only two OTUs in group I.1a after ozonation, which were identical to those detected on GAC. It suggests that ozonation plays an important role in determining AOA diversity on GAC. Further study on the cell-specific activity of AOA and AOB is necessary to understand their contributions to in situ nitrification performance.

  1. Three approaches for estimating recovery factors in carbon dioxide enhanced oil recovery

    Science.gov (United States)

    Verma, Mahendra K.

    2017-07-17

    PrefaceThe Energy Independence and Security Act of 2007 authorized the U.S. Geological Survey (USGS) to conduct a national assessment of geologic storage resources for carbon dioxide (CO2) and requested the USGS to estimate the “potential volumes of oil and gas recoverable by injection and sequestration of industrial carbon dioxide in potential sequestration formations” (42 U.S.C. 17271(b)(4)). Geologic CO2 sequestration associated with enhanced oil recovery (EOR) using CO2 in existing hydrocarbon reservoirs has the potential to increase the U.S. hydrocarbon recoverable resource. The objective of this report is to provide detailed information on three approaches that can be used to calculate the incremental recovery factors for CO2-EOR. Therefore, the contents of this report could form an integral part of an assessment methodology that can be used to assess the sedimentary basins of the United States for the hydrocarbon recovery potential using CO2-EOR methods in conventional oil reservoirs.

  2. Carbon nanomaterials enhance survival of Agapanthus praecox callus after cryopreservation by vitrification.

    Science.gov (United States)

    Chen, S M; Ren, L; Zhang, D; Zhang, Y F; Shen, X H

    Adding exogenous compounds is an effective way to improve cell survival after cryopreservation. Carbon nanomaterials (CNMs) are novel exogenous substances with small particle size and good biocompatibility. In this work, four types of CNMs were used for the cryopreservation of Agapanthus praecox callus and their possible effects and mechanism of action were analyzed. The thermal properties of the vitrification solutions tested were detected by differential scanning calorimetry. Raman spectroscopy and transmission electron microscopy analyses were used to study the distribution of CNMs inside cells. The MDA/H2O2 contents were measured to evaluate the toxicity of CNMs to cells. Supplementation of PVS2 with various CNMs at different concentrations could enhance survival. The most effective concentration was 0.3 g/L C60, which increased survival by 159% compared to untreated controls and decreased the MDA and H2O2 contents. Single-walled carbon nanotubes (SWCNTs) and C60 entered callus cells. C60 was found only in mitochondria, whereas SWCNTs were located only around the cell walls.

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

    Science.gov (United States)

    Wang, Zhihua; Teng, Xu; Lu, Chao

    2012-04-21

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

  4. Graphite Nanoplatelet Modified Epoxy Resin for Carbon Fibre Reinforced Plastics with Enhanced Properties

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-01-01

    Full Text Available A simple approach to deliver graphene or graphite nanoplatelets (GNPs into carbon fibre reinforced plastic (CFRPs to enhance the multifunctional properties of carbon/epoxy laminates was demonstrated. GNPs improved the typically low interlaminar mechanical, thermal, and electrical properties of CFRPs after direct vacuum infusion of GNP doped resin obtained via in situ exfoliation by three-roll milling (TRM. Compared to high shear mixing or probe ultrasonication, TRM produces higher shear rates and stresses to exfoliate and finely disperse GNP particles within an epoxy matrix. This environmentally friendly and industrial scalable process does not require the use of solvents, additives, or chemical treatments. The flexural modulus and interlaminar shear strength (ILSS of CFRPs was increased by 15% and by 18%, respectively, with the addition of 5 wt.% in situ exfoliated GNP in the doped epoxy resin. Out-of-plane electrical and thermal conductivity, at the same filler content, were, respectively, improved by nearly two orders of magnitude and 50%.

  5. Mesoscale ocean fronts enhance carbon export due to gravitational sinking and subduction.

    Science.gov (United States)

    Stukel, Michael R; Aluwihare, Lihini I; Barbeau, Katherine A; Chekalyuk, Alexander M; Goericke, Ralf; Miller, Arthur J; Ohman, Mark D; Ruacho, Angel; Song, Hajoon; Stephens, Brandon M; Landry, Michael R

    2017-02-07

    Enhanced vertical carbon transport (gravitational sinking and subduction) at mesoscale ocean fronts may explain the demonstrated imbalance of new production and sinking particle export in coastal upwelling ecosystems. Based on flux assessments from (238)U:(234)Th disequilibrium and sediment traps, we found 2 to 3 times higher rates of gravitational particle export near a deep-water front (305 mg C⋅m(-2)⋅d(-1)) compared with adjacent water or to mean (nonfrontal) regional conditions. Elevated particle flux at the front was mechanistically linked to Fe-stressed diatoms and high mesozooplankton fecal pellet production. Using a data assimilative regional ocean model fit to measured conditions, we estimate that an additional ∼225 mg C⋅m(-2)⋅d(-1) was exported as subduction of particle-rich water at the front, highlighting a transport mechanism that is not captured by sediment traps and is poorly quantified by most models and in situ measurements. Mesoscale fronts may be responsible for over a quarter of total organic carbon sequestration in the California Current and other coastal upwelling ecosystems.

  6. Enhanced photocurrent density of HTM-free perovskite solar cells by carbon quantum dots

    Science.gov (United States)

    Zou, Haiyuan; Guo, Daipeng; He, Bowen; Yu, Jiaguo; Fan, Ke

    2018-02-01

    Full-printable and hole transport material (HTM)-free perovskite solar cells (PSCs) with carbon counter electrodes feature high stability and low cost. However, the perovskite film prepared by conventional one-step solution-coating method always shows a relatively poor coverage on the substrate, leading to the limit of the photocurrent density. In this study, we incorporated carbon quantum dots (CQDs) in the perovskite films, and investigated their effects on the performance of TiO2 nanosheet-based and HTM-free PSCs. It was found that the addition of CQDs to the perovskite film can enhance the photocurrent density of PSCs, and the optimal PSC with 0.1% CQDs evolved 60% higher photocurrent density than the pristine one. The improved photocurrent density was attributed to the heterogeneous nuclei derived from CQDs during perovskite crystallization, which would increase amount of perovskite nuclei and form a fine perovskite grain, leading to a better coverage on the substrate. Moreover, due to the excellent conductivity, CQDs in perovskite films could efficiently transport the photo-excited electrons, accelerating the separation and mobilization of charge carriers. This study presents the incorporation of CQDs in perovskite as an efficient approach to promote the performance of HTM-free PSCs.

  7. Enhanced priming of old, not new soil carbon at elevated atmospheric CO2

    DEFF Research Database (Denmark)

    Vestergard, Mette; Reinsch, Sabine; Bengtson, Per

    2016-01-01

    Rising atmospheric CO2 concentrations accompanied by global warming and altered precipitation patterns calls for assessment of long-term effects of these global changes on carbon (C) dynamics in terrestrial ecosystems, as changes in net C exchange between soil and atmosphere will impact the atmos......Rising atmospheric CO2 concentrations accompanied by global warming and altered precipitation patterns calls for assessment of long-term effects of these global changes on carbon (C) dynamics in terrestrial ecosystems, as changes in net C exchange between soil and atmosphere will impact...... the atmospheric CO2 concentration profoundly. In many ecosystems, including the heath/grassland system studied here, increased plant production at elevated CO2 increase fresh C input from litter and root exudates to the soil and concurrently decrease soil N availability. Supply of labile C to the soil may...... CO2 exposure. Further, we hypothesized that long-term warming would enhance SOC priming rates, whereas drought would decrease the priming response.We incubated soil from a long-term, full-factorial climate change field experiment, with the factors elevated atmospheric CO2 concentration, warming...

  8. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    Science.gov (United States)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  9. Enhanced Electrical Networks of Stretchable Conductors with Small Fraction of Carbon Nanotube/Graphene Hybrid Fillers.

    Science.gov (United States)

    Oh, Jae Young; Jun, Gwang Hoon; Jin, Sunghwan; Ryu, Ho Jin; Hong, Soon Hyung

    2016-02-10

    Carbon nanotubes (CNTs) and graphene are known to be good conductive fillers due to their favorable electrical properties and high aspect ratios and have been investigated for application as stretchable composite conductors. A stretchable conducting nanocomposite should have a small fraction of conductive filler material to maintain stretchability. Here we demonstrate enhanced electrical networks of nanocomposites via the use of a CNT-graphene hybrid system using a small mass fraction of conductive filler. The CNT-graphene hybrid system exhibits synergistic effects that prevent agglomeration of CNTs and graphene restacking and reduce contact resistance by formation of 1D(CNT)-2D(graphene) interconnection. These effects resulted in nanocomposite materials formed of multiwalled carbon nanotubes (MWCNTs), thermally reduced graphene (TRG), and polydimethylsiloxane (PDMS), which had a higher electrical conductivity compared with MWCNT/PDMS or TRG/PDMS nanocomposites until specific fraction that is sufficient to form electrical network among conductive fillers. These nanocomposite materials maintained their electrical conductivity when 60% strained.

  10. Enhancement of osteogenesis on micro/nano-topographical carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite biocomposite.

    Science.gov (United States)

    Xu, Anxiu; Liu, Xiaochen; Gao, Xiang; Deng, Feng; Deng, Yi; Wei, Shicheng

    2015-03-01

    As an FDA-approved implantable material, carbon fiber-reinforced polyetheretherketone (CFRPEEK) possesses excellent mechanical properties similar to those of human cortical bone and is a prime candidate to replace conventional metallic implants. The bioinertness and inferior osteogenic properties of CFRPEEK, however, limit its clinical application as orthopedic/dental implants. The present work aimed at developing a novel carbon fiber-reinforced polyetheretherketone-nanohydroxyapatite (PEEK/CF/n-HA) ternary biocomposite with micro/nano-topographical surface for the enhancement of the osteogenesis as a potential bioactive material for bone grafting and bone tissue-engineering applications. The combined modification of oxygen plasma and sand-blasting could improve the hydrophily and generate micro/nano-topographical structures on the surface of the CFRPEEK-based ternary biocomposite. The results clearly showcased that the micro-/nano-topographical PEEK/n-HA/CF ternary biocomposite demonstrated the outstanding ability to promote the proliferation and differentiation of MG-63 cells in vitro as well as to boost the osseointegration between implant and bone in vivo, thereby boding well application to bone tissue engineering. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Carbon-tuned bonding method significantly enhanced the hydrogen storage of BN-Li complexes.

    Science.gov (United States)

    Deng, Qing-ming; Zhao, Lina; Luo, You-hua; Zhang, Meng; Zhao, Li-xia; Zhao, Yuliang

    2011-11-01

    Through first-principles calculations, we found doping carbon atoms onto BN monolayers (BNC) could significantly strengthen the Li bond on this material. Unlike the weak bond strength between Li atoms and the pristine BN layer, it is observed that Li atoms are strongly hybridized and donate their electrons to the doped substrate, which is responsible for the enhanced binding energy. Li adsorbed on the BNC layer can serve as a high-capacity hydrogen storage medium, without forming clusters, which can be recycled at room temperature. Eight polarized H(2) molecules are attached to two Li atoms with an optimal binding energy of 0.16-0.28 eV/H(2), which results from the electrostatic interaction of the polarized charge of hydrogen molecules with the electric field induced by positive Li atoms. This practical carbon-tuned BN-Li complex can work as a very high-capacity hydrogen storage medium with a gravimetric density of hydrogen of 12.2 wt%, which is much higher than the gravimetric goal of 5.5 wt % hydrogen set by the U.S. Department of Energy for 2015.

  12. Enhanced dispersion of multiwall carbon nanotubes in natural rubber latex nanocomposites by surfactants bearing phenyl groups.

    Science.gov (United States)

    Mohamed, Azmi; Anas, Argo Khoirul; Bakar, Suriani Abu; Ardyani, Tretya; Zin, Wan Manshol W; Ibrahim, Sofian; Sagisaka, Masanobu; Brown, Paul; Eastoe, Julian

    2015-10-01

    Here is presented a systematic study of the dispersibility of multiwall carbon nanotubes (MWCNTs) in natural rubber latex (NR-latex) assisted by a series of single-, double-, and triple-sulfosuccinate anionic surfactants containing phenyl ring moieties. Optical polarising microscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy have been performed to obtain the dispersion-level profiles of the MWCNTs in the nanocomposites. Interestingly, a triple-chain, phenyl-containing surfactant, namely sodium 1,5-dioxo-1,5-bis(3-phenylpropoxy)-3-((3-phenylpropoxy)carbonyl) pentane-2-sulfonate (TCPh), has a greater capacity the stabilisation of MWCNTs than a commercially available single-chain sodium dodecylbenzenesulfonate (SDBS) surfactant. TCPh provides significant enhancements in the electrical conductivity of nanocomposites, up to ∼10(-2) S cm(-1), as measured by a four-point probe instrument. These results have allowed compilation of a road map for the design of surfactant architectures capable of providing the homogeneous dispersion of MWCNTs required for the next generation of polymer-carbon-nanotube materials, specifically those used in aerospace technology. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Iron-impregnated granular activated carbon for arsenic removal from drinking water

    Science.gov (United States)

    Chang, Qigang

    conducted to investigate the performance of Fe-GACs in real implementations using groundwater taken from a former superfund site in North Dakota. Fe-GACs can remove arsenic below 10 microg/L and the performance of Fe-GACs was significantly enhanced with increasing empty bed contact time.

  14. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments.

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R; Collins, Donald R; Molina, Mario J; Zhang, Renyi

    2016-04-19

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  15. Carbon nanotube dry adhesives with temperature-enhanced adhesion over a large temperature range

    Science.gov (United States)

    Xu, Ming; Du, Feng; Ganguli, Sabyasachi; Roy, Ajit; Dai, Liming

    2016-11-01

    Conventional adhesives show a decrease in the adhesion force with increasing temperature due to thermally induced viscoelastic thinning and/or structural decomposition. Here, we report the counter-intuitive behaviour of carbon nanotube (CNT) dry adhesives that show a temperature-enhanced adhesion strength by over six-fold up to 143 N cm-2 (4 mm × 4 mm), among the strongest pure CNT dry adhesives, over a temperature range from -196 to 1,000 °C. This unusual adhesion behaviour leads to temperature-enhanced electrical and thermal transports, enabling the CNT dry adhesive for efficient electrical and thermal management when being used as a conductive double-sided sticky tape. With its intrinsic thermal stability, our CNT adhesive sustains many temperature transition cycles over a wide operation temperature range. We discover that a `nano-interlock' adhesion mechanism is responsible for the adhesion behaviour, which could be applied to the development of various dry CNT adhesives with novel features.

  16. Gas enhanced magnetic resonance angiography of the cerebrum using carbon dioxide and oxygen - preliminary results

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Hansen, Kristoffer Lindskov; Ohlhues, Anders

    and the meninges may obscure the signal from the arteries of interest. It is known that oxygen enhances the T1-weighted signal and that carbon dioxide increases the arterial blood flow. This paper presents preliminary results of gas enhanced MRA using combinations of atmospheric air, O2 and CO2. Subjects...... and Methods Two healthy volunteers were scanned during inhalation of three different gas mixtures: Gas I (air), Gas II (5% CO2, 21 % O2, 74 % N2), Gas III (5% CO2, 95% O2). For each gas mixture a time of flight (TOF) series on the cerebral arteries was performed. Following each TOF series an ECG-gated phase...... compared. Results The TOF series showed an increase in MRA signal and vessel conspicuousness, when adding CO2 to air (gas I vs. gas II) and an additional increase was seen on MRA when adding O2 to CO2 (gas II vs. gas III). The increase in MRA signal was present on both volunteers. The volume flow increased...

  17. Growing and Etching MoS2 on Carbon Nanotube Film for Enhanced Electrochemical Performance

    Directory of Open Access Journals (Sweden)

    Weiyu Xu

    2016-09-01

    Full Text Available In this work we directly synthesized molybdenum disulfide (MoS2 nanosheets on carbon nanotube film (MoS2@CNT via a two-step chemical vapor deposition method (CVD. By etching the obtained MoS2@CNT into 10% wt HNO3, the morphology of MoS2 decorated on CNT bundles was modulated, resulting in more catalytic active MoS2 edges being exposed for significantly enhanced electrochemical performance. Our results revealed that an 8 h acid etching sample exhibited the best performance for the oxygen evolution reaction, i.e., the current density reached 10 mA/cm2 under 375 mV over-potential, and the tafel slope was as low as 94 mV/dec. The enhanced behavior was mainly originated from the more catalytic sites in MoS2 induced by the acid etching treatment and the higher conductivity from the supporting CNT films. Our study provides a new route to produce two-dimensional layers on CNT films with tunable morphology, and thus may open a window for exploring its promising applications in the fields of catalytic-, electronic-, and electrochemical-related fields.

  18. Enhanced performance of microbial fuel cell with a bacteria/multi-walled carbon nanotube hybrid biofilm

    Science.gov (United States)

    Zhang, Peng; Liu, Jia; Qu, Youpeng; Zhang, Jian; Zhong, Yingjuan; Feng, Yujie

    2017-09-01

    The biofilm on the anode of a microbial fuel cell (MFC) is a vital component in system, and its formation and characteristic determines the performance of the system. In this study, a bacteria/Multi-Walled Carbon Nanotube (MWCNT) hybrid biofilm is fabricated by effectively inserting the MWCNTs into the anode biofilm via an adsorption-filtration method. This hybrid biofilm has been demonstrated to be an efficient structure for improving an anode biofilm performance. Electrochemical impedance spectroscopy (EIS) results show that the hybrid biofilm takes advantage of the conductivity and structure of MWCNT to enhance the electron transfer and substrate diffusion of the biofilm. With this hybrid biofilm, the current density, power density and coulombic efficiency are increased by 46.2%, 58.8% and 84.6%, respectively, relative to naturally grown biofilm. Furthermore, the start-up time is reduced by 53.8% compared with naturally grown biofilm. The perturbation test demonstrates that this type of hybrid biofilm exhibits strong adsorption ability and enhances the biofilm's resistance to a sudden change of substrate concentration. The superior performance of the hybrid biofilm with MWCNT ;nanowire; matrix compared with naturally grown biofilm demonstrates its great potential for boosting the performance of MFCs.

  19. Tomato Seed Coat Permeability to Selected Carbon Nanomaterials and Enhancement of Germination and Seedling Growth.

    Science.gov (United States)

    Ratnikova, Tatsiana A; Podila, Ramakrishna; Rao, Apparao M; Taylor, Alan G

    2015-01-01

    Seed coat permeability was examined using a model that tested the effects of soaking tomato (Solanum lycopersicon) seeds in combination with carbon-based nanomaterials (CBNMs) and ultrasonic irradiation (US). Penetration of seed coats to the embryo by CBNMs, as well as CBNMs effects on seed germination and seedling growth, was examined. Two CBNMs, C60(OH)20 (fullerol) and multiwalled nanotubes (MWNTs), were applied at 50 mg/L, and treatment exposure ranged from 0 to 60 minutes. Bright field, fluorescence, and electron microscopy and micro-Raman spectroscopy provided corroborating evidence that neither CBNM was able to penetrate the seed coat. The restriction of nanomaterial (NM) uptake was attributed to the semipermeable layer located at the innermost layer of the seed coat adjacent to the endosperm. Seed treatments using US at 30 or 60 minutes in the presence of MWNTs physically disrupted the seed coat; however, the integrity of the semipermeable layer was not impaired. The germination percentage and seedling length and weight were enhanced in the presence of MWNTs but were not altered by C60(OH)20. The combined exposure of seeds to NMs and US provided insight into the nanoparticle-seed interaction and may serve as a delivery system for enhancing seed germination and early seedling growth.

  20. Structural insight into activity enhancement and inhibition of H64A carbonic anhydrase II by imidazoles.

    Science.gov (United States)

    Aggarwal, Mayank; Kondeti, Bhargav; Tu, Chingkuang; Maupin, C Mark; Silverman, David N; McKenna, Robert

    2014-03-01

    Human carbonic anhydrases (CAs) are zinc metalloenzymes that catalyze the hydration and dehydration of CO2 and HCO3 (-), respectively. The reaction follows a ping-pong mechanism, in which the rate-limiting step is the transfer of a proton from the zinc-bound solvent (OH(-)/H2O) in/out of the active site via His64, which is widely believed to be the proton-shuttling residue. The decreased catalytic activity (∼20-fold lower with respect to the wild type) of a variant of CA II in which His64 is replaced with Ala (H64A CA II) can be enhanced by exogenous proton donors/acceptors, usually derivatives of imidazoles and pyridines, to almost the wild-type level. X-ray crystal structures of H64A CA II in complex with four imidazole derivatives (imidazole, 1--methylimidazole, 2--methylimidazole and 4-methylimidazole) have been determined and reveal multiple binding sites. Two of these imidazole binding sites have been identified that mimic the positions of the 'in' and 'out' rotamers of His64 in wild-type CA II, while another directly inhibits catalysis by displacing the zinc-bound solvent. The data presented here not only corroborate the importance of the imidazole side chain of His64 in proton transfer during CA catalysis, but also provide a complete structural understanding of the mechanism by which imidazoles enhance (and inhibit when used at higher concentrations) the activity of H64A CA II.

  1. Carbon dots/BiOCl films with enhanced visible light photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weitian; Yu, Xiang; Shen, Yinghua; Chen, Hongbin; Zhu, Yi, E-mail: tzhury@jnu.edu.cn; Zhang, Yuanming [Jinan University, Department of Chemistry (China); Meng, Hui [Jinan University, Siyuan laboratory, Guangzhou Key Laboratory of Vacuum Coating Technologies and New Energy Materials, Department of Physics (China)

    2017-02-15

    Novel carbon dots with a diameter of 6 nm modified BiOCl (CDs/BiOCl) photocatalyst on FTO was synthesized via a facile immobilization method at room temperature. The crystalline structures, morphologies, optical properties, and photocatalytic properties were studied. The results showed that the CDs/BiOCl films exhibited higher photocatalytic activity than pure BiOCl. The 4 wt% CDs/BiOCl film showed the best photocatalytic activity, which was about eight times than that of pure BiOCl and excellent recyclability even after four recycles. Compared with other film photocatalysts, the photocatalytic activity of 4 wt% CDs/BiOCl was also higher than that of many other photocatalysts. The enhanced activity was ascribed to the enhanced light adsorption and the improvement of charge separation. Holes and superoxide radicals ·O{sub 2}{sup −} were revealed as the dominant reactive species. The photocatalytic mechanism was proposed based on the results.

  2. Greener corona discharge for enhanced wind generation with a simple dip-coated carbon nanotube decoration

    Science.gov (United States)

    Wu, Yishan; Li, Jun; Ye, Jianchun; Chen, Xiaohong; Li, Huili; Huang, Sumei; Zhao, Ran; Ou-Yang, Wei

    2017-10-01

    Corona discharge-induced wind (CDIW) has been widely utilized in production lines in the food and semiconductor industries and in indoor devices such as electrostatic precipitators. Some ozone is inevitably emitted, posing serious health risks to respiratory system and lung function of a human being. In this work, a greener corona discharge with enhanced wind generation for a needle-to-cylinder discharge structure is demonstrated using a simple dip-coating method to attach carbon nanotubes (CNTs) to the discharge electrode of a stainless steel needle. Compared with a conventional discharge electrode without CNT decoration, the velocity of the CDIW is greatly enhanced, the onset voltage is lowered, the energy conversion efficiency is greatly improved and the concentration of generated ozone is much reduced, making this easy method of CNT decoration a promising candidate for greener corona discharge systems. In addition, several impact factors for improved performance are discussed mathematically and phenomenologically, providing an insight into the corona discharge and wind generation.

  3. Fe Core–Carbon Shell Nanoparticles as Advanced MRI Contrast Enhancer

    Directory of Open Access Journals (Sweden)

    Rakesh P. Chaudhary

    2017-10-01

    Full Text Available The aim of this study is to fabricate a hybrid composite of iron (Fe core–carbon (C shell nanoparticles with enhanced magnetic properties for contrast enhancement in magnetic resonance imaging (MRI. These new classes of magnetic core–shell nanoparticles are synthesized using a one-step top–down approach through the electric plasma discharge generated in the cavitation field in organic solvents by an ultrasonic horn. Transmission electron microscopy (TEM observations revealed the core–shell nanoparticles with 10–85 nm in diameter with excellent dispersibility in water without any agglomeration. TEM showed the structural confirmation of Fe nanoparticles with body centered cubic (bcc crystal structure. Magnetic multi-functional hybrid composites of Fe core–C shell nanoparticles were then evaluated as negative MRI contrast agents, displaying remarkably high transverse relaxivity (r2 of 70 mM−1·S−1 at 7 T. This simple one-step synthesis procedure is highly versatile and produces desired nanoparticles with high efficacy as MRI contrast agents and potential utility in other biomedical applications.

  4. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R.; Collins, Donald R.; Molina, Mario J.

    2016-04-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  5. Enhanced Structural, Thermal, and Electrical Properties of Multiwalled Carbon Nanotubes Hybridized with Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Yusliza Yusof

    2016-01-01

    Full Text Available The objective of this study is to evaluate the structural, thermal, and electrical properties of multiwalled carbon nanotubes (MWNT hybridized with silver nanoparticles (AgNP obtained via chemical reduction of aqueous silver salt assisted with sodium dodecyl sulphate (SDS as stabilizing agent. Transmission electron microscopy (TEM reveals microstructural analysis of the MWNT-Ag hybrids. The Fourier transform infrared (FTIR spectra prove the interactions between the AgNP and carboxyl groups of the MWNT. Raman spectra reveal that the D- to G-band intensity ratios ID/IG and ID′/IG increase upon the deposition of AgNP onto the surface of the MWNT. Thermogravimetric analysis (TGA shows that the MWNT-Ag hybrids decompose at a much faster rate and the weight loss decreased considerably due to the presence of AgNP. Nonlinearity of current-voltage (I-V curves indicates that electrical transport of pristine MWNT is enhanced when AgNP is induced as charge carriers in the MWNT-Ag hybrids. The threshold voltage Vth value for the MWNT doped with a maximum of 70 vol% of AgNP was substantially reduced by 65% relative to the pristine MWNT. The MWNT-Ag hybrids have a favourable electrical characteristic with a low threshold voltage that shows enhancement mode for field-effect transistor (FET applications.

  6. Mineral-Based Coating of Plasma-Treated Carbon Fibre Rovings for Carbon Concrete Composites with Enhanced Mechanical Performance

    Science.gov (United States)

    Schneider, Kai; Lieboldt, Matthias; Liebscher, Marco; Fröhlich, Maik; Hempel, Simone; Butler, Marko; Schröfl, Christof; Mechtcherine, Viktor

    2017-01-01

    Surfaces of carbon fibre roving were modified by means of a low temperature plasma treatment to improve their bonding with mineral fines; the latter serving as an inorganic fibre coating for the improved mechanical performance of carbon reinforcement in concrete matrices. Variation of the plasma conditions, such as gas composition and treatment time, was accomplished to establish polar groups on the carbon fibres prior to contact with the suspension of mineral particles in water. Subsequently, the rovings were implemented in a fine concrete matrix and their pull-out performance was assessed. Every plasma treatment resulted in increased pull-out forces in comparison to the reference samples without plasma treatment, indicating a better bonding between the mineral coating material and the carbon fibres. Significant differences were found, depending on gas composition and treatment time. Microscopic investigations showed that the samples with the highest pull-out force exhibited carbon fibre surfaces with the largest areas of hydration products grown on them. Additionally, the coating material ingresses into the multifilament roving in these specimens, leading to better force transfer between individual carbon filaments and between the entire roving and surrounding matrix, thus explaining the superior mechanical performance of the specimens containing appropriately plasma-treated carbon roving. PMID:28772719

  7. Removal of microcystin-LR from spiked water using either activated carbon or anthracite as filter material.

    Science.gov (United States)

    Drogui, Patrick; Daghrir, Rimeh; Simard, Marie-Christine; Sauvageau, Christine; Blais, Jean François

    2012-01-01

    The occurrence of cyanobacterial toxins (blue-green algae) in drinking water sources is a big concern for human health. Removal of microcystin-LR (MC-LR) from drinking water was evaluated at the laboratory pilot scale using either granular activated carbon (GAC) or powdered activated carbon (PAC) and compared with the treatment using anthracite as filter material. Virgin GAC was more effective at removing MC-LR (initial concentration ranging from 9 to 47 microg L(-1)) to reach the World Health Organization recommended level (1.0 microg L(-1)). When the GAC filter was colonized by bacteria, the filter became less effective at removing MC-LR owing to competitive reactions occurring between protein adsorption (released by bacteria) and MC-LR adsorption. Using PAC, the concentration of MC-LR decreased from 22 to 3 microg L(-1) (removal of 86% of MC-LR) by the addition of 100 mg PAC L(-1).

  8. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    Science.gov (United States)

    Li, Jian; Shashurin, Alexey; Kundrapu, Madhusudhan; Keidar, Michael

    2012-02-02

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

  9. Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

    Science.gov (United States)

    Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

    2017-08-01

    Continuous flow experiments (450 mL min -1 ) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 5  UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

  10. Identification of Gene Transcription Start Sites and Enhancers Responding to Pulmonary Carbon Nanotube Exposure in Vivo.

    Science.gov (United States)

    Bornholdt, Jette; Saber, Anne Thoustrup; Lilje, Berit; Boyd, Mette; Jørgensen, Mette; Chen, Yun; Vitezic, Morana; Jacobsen, Nicklas Raun; Poulsen, Sarah Søs; Berthing, Trine; Bressendorff, Simon; Vitting-Seerup, Kristoffer; Andersson, Robin; Hougaard, Karin Sørig; Yauk, Carole L; Halappanavar, Sabina; Wallin, Håkan; Vogel, Ulla; Sandelin, Albin

    2017-04-25

    Increased use of nanomaterials in industry, medicine, and consumer products has raised concerns over their toxicity. To ensure safe use of nanomaterials, understanding their biological effects at the molecular level is crucial. In particular, the regulatory mechanisms responsible for the cascade of genes activated by nanomaterial exposure are not well-characterized. To this end, we profiled the genome-wide usage of gene transcription start sites and linked active enhancer regions in lungs of C57BL/6 mice 24 h after intratracheal instillation of a single dose of the multiwalled carbon nanotube (MWCNT) Mitsui-7. Our results revealed a massive gene regulatory response, where expression of key inflammatory genes (e.g., Csf3, Il24, and Fgf23) was increased >100-fold 24 h after Mitsui-7 exposure. Many of the Mitsui-7-responsive transcription start sites were alternative transcription start sites for known genes, and the number of alternative transcription start sites used in a given gene was correlated with overall Mitsui-7 response. Strikingly, genes that were up-regulated after Mitsui-7 exposure only through their main annotated transcription start site were linked to inflammatory and defense responses, while genes up-regulated only through alternative transcription start sites were functionally heterogeneous and not inflammation-associated. Furthermore, we identified almost 12 000 active enhancers, many of which were Mitsui-7-responsive, and we identified similarly responding putative target genes. Overall, our study provides the location and activity of Mitsui-7-induced enhancers and transcription start sites, providing a useful resource for targeted experiments elucidating the biological effects of nanomaterials and the identification of biomarkers for early detection of MWCNT-induced inflammation.

  11. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon

    Science.gov (United States)

    Lewis, Ariel S.; Huntington, Thomas G.; Marvin-DiPasquale, Mark C.; Amirbahman, Aria

    2016-01-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment.

  12. Mercury remediation in wetland sediment using zero-valent iron and granular activated carbon.

    Science.gov (United States)

    Lewis, Ariel S; Huntington, Thomas G; Marvin-DiPasquale, Mark C; Amirbahman, Aria

    2016-05-01

    Wetlands are hotspots for production of toxic methylmercury (MeHg) that can bioaccumulate in the food web. The objective of this study was to determine whether the application of zero-valent iron (ZVI) or granular activated carbon (GAC) to wetland sediment could reduce MeHg production and bioavailability to benthic organisms. Field mesocosms were installed in a wetland fringing Hodgdon Pond (Maine, USA), and ZVI and GAC were applied. Pore-water MeHg concentrations were lower in treated compared with untreated mesocosms; however, sediment MeHg, as well as total Hg (THg), concentrations were not significantly different between treated and untreated mesocosms, suggesting that smaller pore-water MeHg concentrations in treated sediment were likely due to adsorption to ZVI and GAC, rather than inhibition of MeHg production. In laboratory experiments with intact vegetated sediment clumps, amendments did not significantly change sediment THg and MeHg concentrations; however, the mean pore-water MeHg and MeHg:THg ratios were lower in the amended sediment than the control. In the laboratory microcosms, snails (Lymnaea stagnalis) accumulated less MeHg in sediment treated with ZVI or GAC. The study results suggest that both GAC and ZVI have potential for reducing MeHg bioaccumulation in wetland sediment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Carbon-coated boron using low-cost naphthalene for substantial enhancement of Jc in MgB2 superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Ranot, Mahipal; Shinde, K. P.; Oh, Y. S.; Kang, S. H.; Jang, S. H.; Hwang, D. Y.; Chung, K. C. [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2017-09-15

    Carbon coating approach is used to prepare carbon-doped MgB{sub 2} bulk samples using low-cost naphthalene (C{sub 10}H{sub 8}) as a carbon source. The coating of carbon (C) on boron (B) powders was achieved by direct pyrolysis of naphthalene at 120 degrees C and then the C-coated B powders were mixed well with appropriate amount of Mg by solid state reaction method. X-ray diffraction analysis revealed that there is a noticeable shift in (100) and (110) Bragg reflections towards higher angles, while no shift was observed in (002) reflections for MgB2 doped with carbon. As compared to un-doped MgB{sub 2}, a systematic enhancement in Jc(H) properties with increasing carbon doping level was observed for naphthalene-derived C-doped MgB{sub 2} samples. The substantial enhancement in Jc is most likely due to the incorporation of C into MgB{sub 2} lattice and the reduction in crystallite size, as evidenced by the increase in the FWHM values for doped samples.

  14. Carbon-enhanced inductively coupled plasma mass spectrometric detection of arsenic and selenium and its application to arsenic speciation

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Sturup, Stefan

    1994-01-01

    Addition of carbon as methanol or ammonium carbonate to the aqueous analyte solutions in combination with increased plasma power input enhanced the inductively coupled plasma mass spectrometry (ICP-MS) signal intensities of arsenic and selenium. In the presence of the optimum 3% v/v methanol...... concentration the signal intensities achieved were about 4500-5000 counts s-1 per ng ml-1 of arsenic and about 700-1100 counts s-1 per ng ml-1 of selenium (Se-82), corresponding to enhancement factors of 3.5-4.5 compared with aqueous solution for the two elements. Differences in sensitivity (calculated...... on the basis of analyte atom) were observed between the individual arsenic species and between the selenium species in aqueous as well as in carbon-added solutions. The presence of 3% v/v methanol in the analyte solutions doubled the level of the background signal for arsenic and selenium, but its fluctuation...

  15. Microbial activity in granular activated carbon filters in drinking water treatment

    NARCIS (Netherlands)

    Knezev, A.

    2015-01-01

    The investigations described are carried out to analyse the microbiological processes in relation to the GAC characteristics and the removal of natural organic matter (NOM) in Granular Activated Carbon filters (GACFs) in water treatment. The main goal of the study was to obtain a qualitative

  16. Optimization of Synthesis Condition for Nanoscale Zero Valent Iron Immobilization on Granular Activated Carbon

    DEFF Research Database (Denmark)

    Mines, Paul D.; Andersen, Henrik Rasmus; Hwang, Yuhoon

    2016-01-01

    economical loss, but also potential risk to human health and environment. Thus, the immobilization onto coarse or structured support is essential. In this study, two representative processes for nZVI immobilization on granular activated carbon (GAC) were evaluated, and optimized conditions for synthesizing...

  17. Fenton-Driven Chemical Regeneration of MTBE-Spent Granular Activated Carbon -- A Pilot Study

    Science.gov (United States)

    MTBE-spent granular activated carbon (GAC) underwent 3 adsorption/oxidation cycles. Pilot-scale columns were intermittently placed on-line at a ground water pump and treat facility, saturated with MTBE, and regenerated with H2O2 under different chemical, physical, and operational...

  18. Enhanced biological phosphorus removal. Carbon sources, nitrate as electron acceptor, and characterization of the sludge community

    Energy Technology Data Exchange (ETDEWEB)

    Christensson, M.

    1997-10-01

    Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-{beta}-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g of glycogen (COD) was consumed per g of acetic acid (COD) taken up. Microscopic investigations revealed a high amount of polyphosphate accumulating organisms (PAO) in the sludge. Isolation and characterisation of bacteria indicated Acinetobacter spp. to be abundant in the sludge, while sequencing of clones obtained in a 16S rDNA clone library showed a large part of the bacteria to be related to the high mole % G+C Gram-positive bacteria and only a minor fraction to be related to the gamma-subclass of proteobacteria to which Acinetobacter belongs. Operation of a similar anaerobic/aerobic laboratory system with ethanol as sole carbon source showed that a high EBPR can be achieved with this compound as carbon source. However, a prolonged detention time in the anaerobic reactor was required. PHA were produced in the anaerobic reactor in an amount of 1.24 g COD per g of soluble DOC taken up, phosphate was released in an amount of 0.4-0.6 g P per g PHA (COD) produced and 0.46 g glycogen (COD) was consumed per g of soluble COD taken up. Studies of the EBPR in the UCT process at the sewage treatment plant in Helsingborg, Sweden, showed the amount of volatile fatty acids (VFA) available to the PAO in the anaerobic stage to be

  19. Surface-Enhanced and Normal Stokes and Anti-Stokes Raman Spectroscopy of Single-Walled Carbon Nanotubes

    Science.gov (United States)

    Kneipp, K.; Kneipp, H.; Corio, P.; Brown, S. D. M.; Shafer, K.; Motz, J.; Perelman, L. T.; Hanlon, E. B.; Marucci, A.; Dresselhaus, G.; Dresselhaus, M. S.

    2000-04-01

    Surface enhancement factors of at least 1012 for the Raman scattering of single-walled carbon nanotubes in contact with fractal silver colloidal clusters result in measuring very narrow Raman bands corresponding to the homogeneous linewidth of the tangential C-C stretching mode in semiconducting nanotubes. Normal and surface-enhanced Stokes and anti-Stokes Raman spectra are discussed in the framework of selective resonant Raman contributions of semiconducting or metallic nanotubes to the Stokes or anti-Stokes spectra, respectively, of the population of vibrational levels due to the extremely strong surface-enhanced Raman process, and of phonon-phonon interactions.

  20. Effects of different carbon sources on enhanced biological phosphorus removal and "Candidatus Accumulibacter" community composition under continuous aerobic condition.

    Science.gov (United States)

    Nittami, Tadashi; Mukai, Masayuki; Uematsu, Keisuke; Yoon, Li Wan; Schroeder, Sarah; Chua, Adeline Seak May; Fukuda, Junji; Fujita, Masafumi; Seviour, Robert J

    2017-12-01

    Previous studies have shown that enhanced biological phosphorus removal (EBPR) performance under continuous aerobic conditions always eventually deteriorates; however, the speed at which this happens depends on the carbon source supplied. The published data suggest that propionate is a better carbon source than acetate is for maintaining operational stability, although it is not clear why. A lab-scale sequencing batch reactor was run initially under conventional anaerobic/aerobic conditions with either acetate or propionate as the carbon source. Chemical and microbiological analyses revealed that both sources performed as expected for such systems. When continuous aerobic conditions were imposed on both these established communities, marked shifts of the "Candidatus Accumulibacter" clades were recorded for both carbon sources. Here, we discuss whether this shift could explain the prolonged EBPR stability observed with propionate.

  1. The influence of N-doped carbon materials on supported Pd: enhanced hydrogen storage and oxygen reduction performance.

    Science.gov (United States)

    Kong, Xiang-Kai; Chen, Qian-Wang; Lun, Zheng-Yan

    2014-02-03

    N-doped graphene has become an important support for Pd in both hydrogen storage and catalytic reactions. The molecular orbitals of carbon materials (including graphene, fullerene, and small carbon clusters) and those of the supported Pd species will hybrid much stronger as N dopants are introduced, owing to the increased electrostatic attraction at the interface. This enhances the carbon substrates' catching force for the supported Pd, preventing its leaching and aggregation in many practical applications. The better dispersion and stabilization of Pd nanoparticles, which are induced by various carbon supports with N-doping, are pleasing to us and could increase their efficiency and facilitate their recycling during various reaction processes in several fields. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Enhanced solar energy absorption by internally-mixed black carbon in snow grains

    Directory of Open Access Journals (Sweden)

    M. G. Flanner

    2012-05-01

    Full Text Available Here we explore light absorption by snowpack containing black carbon (BC particles residing within ice grains. Basic considerations of particle volumes and BC/snow mass concentrations show that there are generally 0.05–109 BC particles for each ice grain. This suggests that internal BC is likely distributed as multiple inclusions within ice grains, and thus the dynamic effective medium approximation (DEMA (Chýlek and Srivastava, 1983 is a more appropriate optical representation for BC/ice composites than coated-sphere or standard mixing approximations. DEMA calculations show that the 460 nm absorption cross-section of BC/ice composites, normalized to the mass of BC, is typically enhanced by factors of 1.8–2.1 relative to interstitial BC. BC effective radius is the dominant cause of variation in this enhancement, compared with ice grain size and BC volume fraction. We apply two atmospheric aerosol models that simulate interstitial and within-hydrometeor BC lifecycles. Although only ~2% of the atmospheric BC burden is cloud-borne, 71–83% of the BC deposited to global snow and sea-ice surfaces occurs within hydrometeors. Key processes responsible for within-snow BC deposition are development of hydrophilic coatings on BC, activation of liquid droplets, and subsequent snow formation through riming or ice nucleation by other species and aggregation/accretion of ice particles. Applying deposition fields from these aerosol models in offline snow and sea-ice simulations, we calculate that 32–73% of BC in global surface snow resides within ice grains. This fraction is smaller than the within-hydrometeor deposition fraction because meltwater flux preferentially removes internal BC, while sublimation and freezing within snowpack expose internal BC. Incorporating the DEMA into a global climate model, we simulate increases in BC/snow radiative forcing of 43–86%, relative to scenarios that apply external optical properties to all BC. We

  3. Predation and transport of persistent pathogens in GAC and slow sand filters: a threat to drinking water safety?

    Science.gov (United States)

    Bichai, Françoise; Dullemont, Yolanda; Hijnen, Wim; Barbeau, Benoit

    2014-11-01

    Zooplankton has been shown to transport internalized pathogens throughout engineered drinking water systems. In this study, experimental measurements from GAC and SSF filtration tests using high influent concentrations of Cryptosporidium (1.3 × 10(6) and 3.3 × 10(4) oocysts L(-1)) and Giardia (4.8 × 10(4) cysts L(-1)) are presented and compared. A predation and transport conceptual model was developed to extrapolate these results to environmental conditions of typical (oo)cyst concentrations in surface water in order to predict concentrations of internalized (oo)cysts in filtered water. Pilot test results were used to estimate transport and survival ratios of internalized (oo)cysts following predation by rotifers in the filter beds. Preliminary indications of lower transport and survival ratios in SSF were found as compared with GAC filters. A probability of infection due to internalized (oo)cysts in filtered water was calculated under likeliest environmental conditions and under a worst-case scenario. Estimated risks under the likeliest environmental scenario were found to fall below the tolerable risk target of 10(-4) infections per person per year. A discussion is presented on the health significance of persistent pathogens that are internalized by zooplankton during granular filtration processes and released into treated water. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. [Treating of algae-laden raw water with GAC-sand dual media deep bed dissolved air flotation/filtration].

    Science.gov (United States)

    Zhang, Sheng; Liu, Yang; Zhang, Xiao-jian; Xie, Shu-guang

    2004-09-01

    GAC-sand dual media deep bed dissolved air flotation/filtration (GSDDB-DAFF) is a new integrated process, its characteristics include: integration of dissolved air flotation and filtration, GAC-sand dual media deep bed filtration, integration of general treatment and advanced treatment. When algae-laden raw water was treated with the new process. The result showed that removal percentage of algae was 95.1%, outlet algae-count was 4.30 x 10(5) cell/L. Removal percentage of chlorophyll-a was 92.2%, outlet chlorophyll-a was 0.88 microg/L. Outlet turbidity was 0.18 NTU, removal percentage of UV254 was 54.3%, outlet UV254 was 0.016 cm(-1), Removal percentage of OC was 63.6%, outlet OC was 0.78 mg/L; outlet had no odor; removal percentage of color was 86.4%, outlet color was 3; outlet Al-residual was 0.011 mg/L which accorded with the quality standard of drinking water. Run time of filter was 36 h, UFRV (Unit Filter Run Volume) was 504 m3/m2.

  5. Ammonium removal pathways and microbial community in GAC-sand dual media filter in drinking water treatment.

    Science.gov (United States)

    Feng, Shuo; Xie, Shuguang; Zhang, Xiaojian; Yang, Zhiyu; Ding, Wei; Liao, Xiaobin; Liu, Yuanyuan; Chen, Chao

    2012-01-01

    A GAC-sand dual media filter (GSF) was devised as an alternative solution for drinking water treatment plant to tackle the raw water polluted by ammonium in place of expensive ozone-GAC processes or bio-pretreatments. The ammonium removal pathways and microbial community in the GSFs were investigated. The concentrations of ammonium, nitrite and nitrate nitrogen were monitored along the filter. Total inorganic nitrogen (TIN) loss occurred during the filtration. For 1 mg ammonium removal, the TIN loss was as high as 0.35 mg, DO consumption was 3.06 mg, and alkalinity consumption was 5.55 mg. It was assumed that both nitrification and denitrification processes occur in the filters to fit the TIN loss and low DO consumption. During the filtration, nitritation, nitrification and nitritation-anaerobic ammonium oxidation processes probably occur, while traditional nitrification and denitrification and simultaneous nitrification and denitrification processes may occur. In the GSFs, Nitrosomonas and Nitrospira are likely to be involved in nitrification processes, while Novosphingobium, Comamonadaceae and Oxalobacteraceae may be involved in denitrification processes.

  6. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Bo, E-mail: willycb@163.com; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Highlights: • The phosphorus doped g-C{sub 3}N{sub 4} photocatalysts are synthesized by a co-pyrolysis procedure. • The crystal phase, morphology, and optical property of P doped g-C{sub 3}N{sub 4} are characterized. • The P doped g-C{sub 3}N{sub 4} photocatalysts show the improved photocatalytic activity. • The possible mechanism for enhanced photocatalytic activity is proposed. - Abstract: Phosphorus doped graphitic carbon nitride (g-C{sub 3}N{sub 4}) was easily synthesized using ammonium hexafluorophosphate (NH{sub 4}PF{sub 6}) as phosphorus source, and ammonium thiocyanate (NH{sub 4}SCN) as g-C{sub 3}N{sub 4} precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C{sub 3}N{sub 4} was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV–vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C{sub 3}N{sub 4} samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C{sub 3}N{sub 4} had a superior photocatalytic activity than that of pristine g-C{sub 3}N{sub 4}, attributing to the phosphorus atoms substituting carbon atoms of g-C{sub 3}N{sub 4} frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C{sub 3}N{sub 4}. Moreover, the tests of radical scavengers demonstrated that the holes (h{sup +}) and superoxide radicals (·O{sub 2}{sup −}) were the main active species for the

  7. Aircraft observations of enhancement and depletion of black carbon mass in the springtime Arctic

    Directory of Open Access Journals (Sweden)

    J. R. Spackman

    2010-10-01

    Full Text Available Understanding the processes controlling black carbon (BC in the Arctic is crucial for evaluating the impact of anthropogenic and natural sources of BC on Arctic climate. Vertical profiles of BC mass loadings were observed from the surface to near 7-km altitude in April 2008 using a Single-Particle Soot Photometer (SP2 during flights on the NOAA WP-3D research aircraft from Fairbanks, Alaska. These measurements were conducted during the NOAA-sponsored Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC project. In the free troposphere, the Arctic air mass was influenced by long-range transport from biomass-burning and anthropogenic source regions at lower latitudes especially during the latter part of the campaign. Average BC mass mixing ratios peaked at about 150 ng BC (kg dry air −1 near 5.5 km altitude in the aged Arctic air mass and 250 ng kg−1 at 4.5 km in biomass-burning influenced air. BC mass loadings were enhanced by up to a factor of 5 in biomass-burning influenced air compared to the aged Arctic air mass. At the bottom of some of the profiles, positive vertical gradients in BC were observed over the sea-ice. The vertical profiles generally occurred in the vicinity of open leads in the sea-ice. In the aged Arctic air mass, BC mass loadings more than doubled with increasing altitude within the ABL and across the boundary layer transition while carbon monoxide (CO remained constant. This is evidence for depletion of BC mass in the ABL. BC mass loadings were positively correlated with O3 in ozone depletion events (ODEs for all the observations in the ABL. Since bromine catalytically destroys ozone in the ABL after being released as molecular bromine in regions of new sea-ice formation at the surface, the BC–O3 correlation suggests that BC particles were removed by a surface process such as dry deposition. We develop a box model to estimate the dry deposition flux of BC

  8. Laser Carbonization of PAN-Nanofiber Mats with Enhanced Surface Area and Porosity.

    Science.gov (United States)

    Go, Dennis; Lott, Philipp; Stollenwerk, Jochen; Thomas, Helga; Möller, Martin; Kuehne, Alexander J C

    2016-10-26

    Here we present a novel laser process to generate carbon nanofiber nonwovens from polyacrylonitrile. We produce carbon nanofabrics via electrospinning followed by infrared laser-induced carbonization, facilitating high surface area and well-controlled hierarchical porosity. The process allows precise control of the carbonization conditions and provides high nanoscale porosity. In comparison with classical thermal carbonization, the laser process produces much higher surface areas and smaller pores. Furthermore, we investigate the carbonization performance and the morphology of polyacrylonitrile nanofibers compounded with graphene nanoplatelet fillers.

  9. Interfacial Microstructure and Enhanced Mechanical Properties of Carbon Fiber Composites Caused by Growing Generation 1-4 Dendritic Poly(amidoamine) on a Fiber Surface.

    Science.gov (United States)

    Gao, Bo; Zhang, Ruliang; Gao, Fucheng; He, Maoshuai; Wang, Chengguo; Liu, Lei; Zhao, Lifen; Cui, Hongzhi

    2016-08-23

    In an attempt to improve the mechanical properties of carbon fiber composites, propagation of poly(amidoamine) (PAMAM) dendrimers by in situ polymerization on a carbon fiber surface was performed. During polymerization processes, PAMAM was grafted on carbon fiber by repeated Michael addition and amidation reactions. The changes in surface microstructure and the chemical composition of carbon fibers before and after modification were investigated by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. All the results indicated that PAMAM was successfully grown on the carbon fiber surface. Such propagation could significantly increase the surface roughness and introduce sufficient polar groups onto the carbon fiber surface, enhancing the surface wettability of carbon fiber. The fractured surface of carbon fiber-reinforced composites showed a great enhancement of interfacial adhesion. Compared with those of desized fiber composites, the interlaminar shear strength and interfacial shear strength of PAMAM/fiber-reinforced composites showed increases of 55.49 and 110.94%, respectively.

  10. Structural insight into activity enhancement and inhibition of H64A carbonic anhydrase II by imidazoles

    Directory of Open Access Journals (Sweden)

    Mayank Aggarwal

    2014-03-01

    Full Text Available Human carbonic anhydrases (CAs are zinc metalloenzymes that catalyze the hydration and dehydration of CO2 and HCO3−, respectively. The reaction follows a ping-pong mechanism, in which the rate-limiting step is the transfer of a proton from the zinc-bound solvent (OH−/H2O in/out of the active site via His64, which is widely believed to be the proton-shuttling residue. The decreased catalytic activity (∼20-fold lower with respect to the wild type of a variant of CA II in which His64 is replaced with Ala (H64A CA II can be enhanced by exogenous proton donors/acceptors, usually derivatives of imidazoles and pyridines, to almost the wild-type level. X-ray crystal structures of H64A CA II in complex with four imidazole derivatives (imidazole, 1-methylimidazole, 2-methylimidazole and 4-methylimidazole have been determined and reveal multiple binding sites. Two of these imidazole binding sites have been identified that mimic the positions of the `in' and `out' rotamers of His64 in wild-type CA II, while another directly inhibits catalysis by displacing the zinc-bound solvent. The data presented here not only corroborate the importance of the imidazole side chain of His64 in proton transfer during CA catalysis, but also provide a complete structural understanding of the mechanism by which imidazoles enhance (and inhibit when used at higher concentrations the activity of H64A CA II.

  11. Enhanced visible-light-driven photocatalytic performance of porous graphitic carbon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Fei, E-mail: feichang@usst.edu.cn [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Li, Chenlu; Luo, Jieru; Xie, Yunchao; Deng, Baoqing [School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Hu, Xuefeng, E-mail: xfhu@yic.ac.cn [Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, Shandong 264003 (China)

    2015-12-15

    Graphical abstract: - Highlights: • Porous g-C{sub 3}N{sub 4} samples were fabricated by a facile pyrolysis method. • As-prepared porous g-C{sub 3}N{sub 4} samples showed remarkably enhanced photocatalytic performance. • Holes and radicals ·O{sub 2}{sup −} exerted dominant roles on the photocatalytic process. - Abstract: In this study, a series of porous graphitic carbon nitride (g-C{sub 3}N{sub 4}) materials were fabricated through a direct pyrolysis of protonated melamine by nitric acid solution. These as-prepared porous samples were characterized by a collection of analytical techniques. It was found that a proper concentration of nitric acid solution involved facilitated to generate samples in tube-like morphology with numerous pores, identified with X-ray diffraction patterns, FT-IR spectra, SEM, TEM, and BET measurements. These g-C{sub 3}N{sub 4} samples were subjected to photocatalytic degradation of dye Rhodamine B (RhB) in aqueous under visible-light irradiation. Under identical conditions, those porous g-C{sub 3}N{sub 4} samples showed significantly improved catalytic performance in comparison with the sample prepared without the introduction of nitric acid. In particularly, the best candidate, sample M1:1, showed an apparent reaction rate nearly 6.2 times that of the unmodified counterpart. The enhancement of photocatalytic performance could be attributed to the favorable porous structure with the enlarged specific surface area and the suitable electronic structure as well. In addition, ESR measurements were conducted for the sake of proposing a photocatalytic degradation mechanism.

  12. Markedly enhanced direct radiative forcing of black carbon particles under polluted urban environments

    Science.gov (United States)

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti; Zeng, Liming; Shao, Min; Wu, Yusheng; Zheng, Jun; Wang, Yuan; Collins, Don; Zhang, Renyi

    2016-04-01

    Black carbon (BC) particles, produced from incomplete fossil fuel combustion and biomass burning, are ubiquitous in the atmosphere and have profound impacts on air quality, human health, weather, and climate. For example, in areas identified as aerosol hotspots, which include many urban centers and megacities worldwide, solar heating by BC particles has been shown to be comparable to warming due to the greenhouse gases2. Although BC represents a key short-lived climate forcer, its direct radiative forcing remains highly uncertain. In particular, the available results of absorption enhancement of BC particles during atmospheric aging are conflicting from the previous studies, leading to a large uncertainty in global radiative transfer calculation. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China and Houston, US, using a novel chamber approach. BC aging exhibits two distinct stages - initial transformation from a fractal to spherical morphology with little absorption variation and the subsequent growth of fully compact particles with a maximum absorption enhancement factor of 2.4. The variation in BC direct radiative forcing is highly dependent of the rate and timescale of aging, with an estimated increase of 0.45 (0.21 - 0.80) W m-2 from fresh to fully aged particles. Our results reveal a high climatic impact in polluted environments due to rapid aging and a clear distinction between urban cities in developed and developing countries for BC particles, highlighting a larger than recognized co-benefit in air quality improvement and climate protection by BC mediation.

  13. Expression of proteins encoded by the Escherichia coli cyn operon: carbon dioxide-enhanced degradation of carbonic anhydrase.

    Science.gov (United States)

    Kozliak, E I; Guilloton, M B; Gerami-Nejad, M; Fuchs, J A; Anderson, P M

    1994-09-01

    Cyanase catalyzes the reaction of cyanate with bicarbonate to give 2CO2. The cynS gene encoding cyanase, together with the cynT gene for carbonic anhydrase, is part of the cyn operon, the expression of which is induced in Escherichia coli by cyanate. The physiological role of carbonic anhydrase is to prevent depletion of cellular bicarbonate during cyanate decomposition due to loss of CO2 (M.B. Guilloton, A.F. Lamblin, E. I. Kozliak, M. Gerami-Nejad, C. Tu, D. Silverman, P.M. Anderson, and J.A. Fuchs, J. Bacteriol. 175:1443-1451, 1993). A delta cynT mutant strain was extremely sensitive to inhibition of growth by cyanate and did not catalyze decomposition of cyanate (even though an active cyanase was expressed) when grown at a low pCO2 (in air) but had a Cyn+ phenotype at a high pCO2. Here the expression of these two enzymes in this unusual system for cyanate degradation was characterized in more detail. Both enzymes were found to be located in the cytosol and to be present at approximately equal levels in the presence of cyanate. A delta cynT mutant strain could be complemented with high levels of expressed human carbonic anhydrase II; however, the mutant defect was not completely abolished, perhaps because the E. coli carbonic anhydrase is significantly less susceptible to inhibition by cyanate than mammalian carbonic anhydrases. The induced E. coli carbonic anhydrase appears to be particularly adapted to its function in cyanate degradation. Active cyanase remained in cells grown in the presence of either low or high pCO2 after the inducer cyanate was depleted; in contrast, carbonic anhydrase protein was degraded very rapidly (minutes) at a high pCO2 but much more slowly (hours) at a low pCO2. A physiological significance of these observations is suggested by the observation that expression of carbonic anhydrase at a high pCO2 decreased the growth rate.

  14. Degradation-by-design: Surface modification with functional substrates that enhance the enzymatic degradation of carbon nanotubes.

    Science.gov (United States)

    Sureshbabu, Adukamparai Rajukrishnan; Kurapati, Rajendra; Russier, Julie; Ménard-Moyon, Cécilia; Bartolini, Isacco; Meneghetti, Moreno; Kostarelos, Kostas; Bianco, Alberto

    2015-12-01

    Biodegradation of carbon-based nanomaterials has been pursued intensively in the last few years, as one of the most crucial issues for the design of safe, clinically relevant conjugates for biomedical applications. In this paper it is demonstrated that specific functional molecules can enhance the catalytic activity of horseradish peroxidase (HRP) and xanthine oxidase (XO) for the degradation of carbon nanotubes. Two different azido coumarins and one cathecol derivative are linked to multi-walled carbon nanotubes (MWCNTs). These molecules are good reducing substrates and strong redox mediators to enhance the catalytic activity of HRP. XO, known to metabolize various molecules mainly in the mammalian liver, including human, was instead used to test the biodegradability of MWCNTs modified with an azido purine. The products of the biodegradation process are characterized by transmission electron microscopy and Raman spectroscopy. The results indicate that coumarin and catechol moieties have enhanced the biodegradation of MWCNTs compared to oxidized nanotubes, likely due to the capacity of these substrates to better interact with and activate HRP. Although azido purine-MWCNTs are degraded less effectively by XO than oxidized nanotubes, the data uncover the importance of XO in the biodegradation of carbon-nanomaterials leading to their better surface engineering for biomedical applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Enhancement of p-nitrophenol adsorption capacity through N2-thermal-based treatment of activated carbons

    Science.gov (United States)

    Álvarez-Torrellas, S.; Martin-Martinez, M.; Gomes, H. T.; Ovejero, G.; García, J.

    2017-08-01

    In this work several activated carbons showing different textural and chemical properties were obtained by chemical and physical activation methods, using a lignocellulosic material (peach stones) as precursor. The activated carbon resulting from the chemical activation, namely as CAC, revealed the best textural properties (SBET = 1521 m2 g-1, pore volume = 0.90 cm3 g-1) and an acidic character. It was found that the activated carbon obtained at 300 °C (under air atmosphere, PAC_air), and those synthesized at 750 °C in presence of N2 flow with bubbling of water/12 M H3PO4 solution (PAC_N2(H2O)/PAC_N2(H3PO4)), respectively, revealed worse textural properties, compared to CAC. Two functionalization treatments, by using sulphuric acid at boiling temperature (PACS) and nitric acid-urea-N2 heating at 800 °C (PAC-NUT), were applied to PAC_air, in order to enhance the adsorption ability of the carbon material. Several techniques were carried out to characterize the physical and chemical properties of the obtained carbon materials. The modification treatments had influence on the carbon surface properties, since the nitric acid-urea-N2 heating treatment led to a carbon material with highly-improved properties (SBET = 679 m2 g-1, pHIEP = 5.3). Accordingly, the original and modified-carbon materials were tested as adsorbents to remove 4-nitrophenol (4-NP), assessing batch and fixed-bed column adsorption tests. PAC-NUT carbon offered the best adsorption behavior (qe = 234 mg g-1), showing a high ability for the removal of 4-NP from water.

  16. Chemosensitizing effects of carbon-based nanomaterials in cancer cells: enhanced apoptosis and inhibition of proliferation as underlying mechanisms.

    Science.gov (United States)

    Erdmann, Kati; Ringel, Jessica; Hampel, Silke; Rieger, Christiane; Huebner, Doreen; Wirth, Manfred P; Fuessel, Susanne

    2014-10-10

    Recent studies have shown that carbon nanomaterials such as carbon nanofibres (CNFs) and multi-walled carbon nanotubes (CNTs) can exert antitumor activities themselves and sensitize cancer cells to conventional chemotherapeutics such as carboplatin and cisplatin. In the present study, the chemosensitizing effect of CNFs and CNTs on cancer cells of urological origin was investigated regarding the underlying mechanisms. Prostate cancer (DU-145, PC-3) and bladder cancer (EJ28) cells were treated with carbon nanomaterials (CNFs, CNTs) and chemotherapeutics (carboplatin, cisplatin) alone as well as in combination for 24 h. Forty-eight(EJ28) or 72 h (DU-145, PC-3) after the end of treatment the effects on cellular proliferation,clonogenic survival, cell death rate and cell cycle distribution were evaluated. Depending on the cell line, simultaneous administration of chemotherapeutics and carbon nanomaterials produced an additional inhibition of cellular proliferation and clonogenic survival of up to 77% and 98%, respectively, compared to the inhibitory effects of the chemotherapeutics alone. These strongly enhanced antiproliferative effects were accompanied by an elevated cell death rate, which was predominantly mediated via apoptosis and not by necrosis. The antitumor effects of combinations with CNTs were less pronounced than those with CNFs. The enhanced effects of the combinatory treatments on cellular function were mostly of additive to partly synergistic nature. Furthermore, cell cycle analysis demonstrated an arrest at the G2/M phase mediated by a monotreatment with chemotherapeutics. Following combinatory treatments, mostly less than or nearly additive increases of cell fractions in the G2/M phase could be observed. In conclusion,the pronounced chemosensitizing effects of CNFs and CNTs were mediated by an enhanced apoptosis and inhibition of proliferation. The combination of carbon-based nanomaterials and conventional chemotherapeutics represents a novel approach

  17. Diatom resting spore ecology drives enhanced carbon export from a naturally iron-fertilized bloom in the Southern Ocean

    Science.gov (United States)

    Salter, Ian; Kemp, Alan E. S.; Moore, C. Mark; Lampitt, Richard S.; Wolff, George A.; Holtvoeth, Jens

    2012-03-01

    Southern Ocean Island systems sustain phytoplankton blooms induced by natural iron fertilization that are important for the uptake of atmospheric carbon dioxide and serve as analogues for past and future climate change. We present data on diatom flux assemblages and the biogeochemical properties of sinking particles to explain the enhanced particulate organic carbon (POC) export fluxes observed in response to natural iron supply in the Crozet Islands region (CROZeX). Moored deep-ocean sediment traps (>2000 m) were located beneath a naturally fertilized island bloom and beneath an adjacent High Nutrient Low Chlorophyll (HNLC) control site. Deep-ocean carbon flux from the naturally-fertilized bloom area was tightly correlated (R = 0.83, n = 12, P fertilized bloom enhanced carbon flux and the resulting Si/C and Si/N ratios were 2.0-3.4-fold and 2.2-3.5-fold lower than those measured in the adjacent HNLC control area. The enhanced carbon export and distinctive stoichiometry observed in naturally fertilized systems is therefore largely not attributable to iron relief of open ocean diatoms, but rather to the advection and growth of diatom species characteristic of island systems and the subsequent flux of resting spores. Carbon export estimates from current natural iron fertilization studies therefore represent a highly specific response of the island systems chosen as natural laboratories and may not be appropriate analogues for the larger Southern Ocean response. The broader implications of our results emphasize the role of phytoplankton diversity and ecology and highlight the need for a species-centered approach in order to understand the regulation of biogeochemical fluxes.

  18. Performance enhancement with powdered activated carbon (PAC) addition in a membrane bioreactor (MBR) treating distillery effluent

    Energy Technology Data Exchange (ETDEWEB)

    Satyawali, Yamini [TERI University, 10, Institutional Area, Vasant Kunj, New Delhi 110070 (India); Balakrishnan, Malini, E-mail: malinib@teri.res.in [TERI University, 10, Institutional Area, Vasant Kunj, New Delhi 110070 (India); Energy and Resources Institute (TERI), Darbari Seth Block, India Habitat Center, Lodhi Road, New Delhi 110003 (India)

    2009-10-15

    This work investigated the effect of powdered activated carbon (PAC) addition on the operation of a membrane bioreactor (MBR) treating sugarcane molasses based distillery wastewater (spentwash). The 8 L reactor was equipped with a submerged 30 {mu}m nylon mesh filter with 0.05 m{sup 2} filtration area. Detailed characterization of the commercial wood charcoal based PAC was performed before using it in the MBR. The MBR was operated over 200 days at organic loading rates (OLRs) varying from 4.2 to 6.9 kg m{sup -3} d{sup -1}. PAC addition controlled the reactor foaming during start up and enhanced the critical flux by around 23%; it also prolonged the duration between filter cleaning. Operation at higher loading rates was possible and for a given OLR, the chemical oxygen demand (COD) removal was higher with PAC addition. However, biodegradation in the reactor was limited and the high molecular weight compounds were not affected by PAC supplementation. The functional groups on PAC appear to interact with the polysaccharide portion of the sludge, which may reduce its propensity to interact with the nylon mesh.

  19. Functionalization of Aligned Carbon Nanotubes to Enhance the Performance of Fuel Cell

    Directory of Open Access Journals (Sweden)

    Jingbo Liu

    2013-12-01

    Full Text Available The focus of this research lies on fundamental research to provide guidelines for the design of new nanocatalyst toward improvement of the performance of proton exchange membrane fuel cells (PEMFCs. To achieve this overarching goal, several specific steps were taken with aims to: (1 provide guidelines for the design of new catalysts; (2 promote nanocatalyst applications towards alternative energy applications; and (3 integrate advanced instrumentation into nanocharacterization and fuel cell (FC electrochemical behavior. In tandem with these goals, the cathode catalysts were extensively refined to improve the performance of PEMFCs and minimize noble metal usage. In this study, the major accomplishment was producing aligned carbon nanotubes (ACNTs, which were then modified by platinum (Pt nanoparticles via a post-functionalization colloidal chemistry approach. The Pt-ACNTs demonstrated improved cathodic catalycity, by building better device endurance and decreased Pt loading. It was also determined that surface mechanical properties, such as elastic modulus and hardness were increased. Collectively, these enhancements provided an improved FC device. The electrochemical analyses indicated that the power density of the PEMFCs was increased to 900 mW/cm2 and current density to 3000 mA/cm2, respectively. The Pt loading was controlled at lower than 0.2 mg/cm2 to decrease the manufacturing expenses.

  20. Uniquely confining Cu2S nanoparticles in graphitized carbon fibers for enhanced oxygen evolution reaction

    Science.gov (United States)

    Zhao, Xiaoqian; Liu, Li; Zhang, Yan; Zhang, Huijuan; Wang, Yu

    2017-08-01

    Up to now, the literature on Cu2S with specific morphology applied to oxygen evolution reaction (OER) in the electrocatalytic field has been limited. In this work, unique peapod-like Cu2S/C exhibiting superb electrocatalytic performance toward OER is successfully synthesized, by employing Cu(OH)2 nanorods as the template and nontoxic glucose as the carbon source and then annealing with sublimed sulfur. It can be seen that this work explores a new application area for Cu2S. More precisely, the novel morphology contributes to increasing the electrochemical active surface area effectively and promoting contact between the Cu2S nanoparticles and the electrolyte. During electrochemical measurements, the peapod-like Cu2S/C shows enhanced electrocatalytic activity with a low overpotential of 401 mV at the current density of 10 mA cm-2 and a Tafel slope of 52 mV dec-1. More importantly, our material is able to maintain stability for at least 8 h at constant potential and the current loss is negligible after 2000 cycles. Obviously, these striking properties fully demonstrate that the peapod-like Cu2S/C as an efficient catalyst shows great promise for OER.

  1. Co-composting solid biowastes with alkaline materials to enhance carbon stabilization and revegetation potential.

    Science.gov (United States)

    Chowdhury, Saikat; Bolan, Nanthi S; Seshadri, Balaji; Kunhikrishnan, Anitha; Wijesekara, Hasintha; Xu, Yilu; Yang, Jianjun; Kim, Geon-Ha; Sparks, Donald; Rumpel, Cornelia

    2016-04-01

    Co-composting biowastes such as manures and biosolids can be used to stabilize carbon (C) without impacting the quality of these biowastes. This study investigated the effect of co-composting biowastes with alkaline materials on C stabilization and monitored the fertilization and revegetation values of these co-composts. The stabilization of C in biowastes (poultry manure and biosolids) was examined by their composting in the presence of various alkaline amendments (lime, fluidized bed boiler ash, flue gas desulphurization gypsum, and red mud) for 6 months in a controlled environment. The effects of co-composting on the biowastes' properties were assessed for different physical C fractions, microbial biomass C, priming effect, potentially mineralizable nitrogen, bioavailable phosphorus, and revegetation of an urban landfill soil. Co-composting biowastes with alkaline materials increased C stabilization, attributed to interaction with alkaline materials, thereby protecting it from microbial decomposition. The co-composted biowastes also increased the fertility of the landfill soil, thereby enhancing its revegetation potential. Stabilization of biowastes using alkaline materials through co-composting maintains their fertilization value in terms of improving plant growth. The co-composted biowastes also contribute to long-term soil C sequestration and reduction of bioavailability of heavy metals.

  2. Enhanced field-dependent conductivity of magnetorheological gels with low-doped carbon nanotubes

    Science.gov (United States)

    Qu, Hang; Yu, Miao; Fu, Jie; Yang, Pingan; Liu, Yuxuan

    2017-10-01

    Magnetorheological gels (MRG) exhibit field-dependent conductivity and controllable mechanical properties. In order to extend their application field, filling a large number of traditional conductive materials is the most common means to enhance the poor conductivity of MRG. In this study, the conductivity of MRG is improved by low-doped carbon nanotubes (CNTs). The influence of CNTs on the magnetoresistance of MRG is discussed from two aspects—the improvement in electrical conductivity and the magnetic sensitivity of conductivity variation. The percolation threshold of CNTs in MRG should be between 1 wt% and 2 wt%. The conductivity of a 4 wt% CNT-doped sample increases more than 28 000 times compared with pure MRG. However, there is a cliff-like drop for the range and rate of conductivity variation when the doping amount of CNTs is between 3 wt% and 4 wt%. Therefore, it is concluded that the optimal mass fraction of CNTs is 3%, which can maintain a suitable variation range and a strong conductivity. Compared with pure MRG, its conductivity increases by at least two orders of magnitude. Finally, a sketch of particle motion simulation is developed to understand the improving mechanism and the effect of CNTs.

  3. Use of carbon dots to enhance UV-blocking of transparent nanocellulose films.

    Science.gov (United States)

    Feng, Xin; Zhao, Yafei; Jiang, Yaoquan; Miao, Miao; Cao, Shaomei; Fang, Jianhui

    2017-04-01

    High-efficient transparent UV-blocking nanocellulose (NC) films were successfully assembled by pressured-extrusion of the composites of carbon dots (CDs), 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical mediated oxidized nanocellulose (ONC) and ZnO nanostructures. ONC nanofibrils were firstly extracted from bamboo fibers and subsequently prepared by applying TEMPO oxidation. The as-obtained CDs-ONC-ZnO films exhibited high visible light transparency, excellent thermal stability and enhanced UV-blocking properties. Compared to the previously designed NC-ZnO films, CDs-ONC-ZnO films presented significant increase of UV-blocking ratio (UVR) with the same amounts of ZnO. Moreover, the UVR of CDs-ONC-s-ZnO film with 4wt% sheet-like ZnO (s-ZnO) at 300nm and 225nm is 92.74% and 98.99%, better than the same condition of CDs-ONC-b-ZnO film added with belt-like ZnO (b-ZnO) and CDs-ONC-p-ZnO film added with commercial particulate ZnO (p-ZnO). An interesting discovery is that when adding 4wt% p-ZnO, the UVR of CDs-ONC-p-ZnO film is very close to the value of NC-s-ZnO film with the same amount of s-ZnO. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. The Enhanced Photo-Electrochemical Detection of Uric Acid on Au Nanoparticles Modified Glassy Carbon Electrode

    Science.gov (United States)

    Shi, Yuting; Wang, Jin; Li, Shumin; Yan, Bo; Xu, Hui; Zhang, Ke; Du, Yukou

    2017-07-01

    In this work, a sensitive and novel method for determining uric acid (UA) has been developed, in which the glassy carbon electrode (GCE) was modified with electrodeposition Au nanoparticles and used to monitor the concentration of UA with the assistant of visible light illumination. The morphology of the Au nanoparticles deposited on GCE surface were characterized by scanning electron microscope (SEM) and the nanoparticles were found to be well-dispersed spheres with the average diameter approaching 26.1 nm. A series of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements have revealed that the introduction of visible light can greatly enhance both the strength and stability of response current due to the surface plasmon resonance (SPR). Specifically, the DPV showed a linear relationship between peak current and UA concentration in the range of 2.8 to 57.5 μM with the equation of I pa (μA) = 0.0121 c UA (μM) + 0.3122 ( R 2 = 0.9987). Herein, the visible light illuminated Au/GCE possesses a potential to be a sensitive electrochemical sensor in the future.

  5. Enhanced electrical conductivities of N-doped carbon nanotubes by controlled heat treatment.

    Science.gov (United States)

    Fujisawa, Kazunori; Tojo, Tomohiro; Muramatsu, Hiroyuki; Elías, Ana L; Vega-Díaz, Sofía M; Tristán-López, Ferdinando; Kim, Jin Hee; Hayashi, Takuya; Kim, Yoong Ahm; Endo, Morinobu; Terrones, Mauricio

    2011-10-05

    The thermal stability of nitrogen (N) functionalities on the sidewalls of N-doped multi-walled carbon nanotubes was investigated at temperatures ranging between 1000 °C and 2000 °C. The structural stability of the doped tubes was then correlated with the electrical conductivity both at the bulk and at the individual tube levels. When as-grown tubes were thermally treated at 1000 °C, we observed a very significant decrease in the electrical resistance of the individual nanotubes, from 54 kΩ to 0.5 kΩ, which is attributed to a low N doping level (e.g. 0.78 at% N). We noted that pyridine-type N was first decomposed whereas the substitutional N was stable up to 1500 °C. For nanotubes heat treated to 1800 °C and 2000 °C, the tubes exhibited an improved degree of crystallinity which was confirmed by both the low R value (I(D)/I(G)) in the Raman spectra and the presence of straight graphitic planes observed in TEM images. However, N atoms were not detected in these tubes and caused an increase in their electrical resistivity and resistance. These partially annealed doped tubes with enhanced electrical conductivities could be used in the fabrication of robust and electrically conducting composites, and these results could be extrapolated to N-doped graphene and other nanocarbons.

  6. Enhanced electrochemical performance of amorphous carbon nanotube-manganese-di-oxide-poly-pyrrole ternary nanohybrid

    Science.gov (United States)

    Pahari, D.; Das, N. S.; Das, B.; Howli, P.; Chattopadhyay, K. K.; Banerjee, D.

    2017-12-01

    Amorphous carbon nanotubes (a-CNTs) manganese di oxide (MnO2)-poly pyrrole (PPy) ternary nanocomposites have been synthesized by a simple chemical route. The as prepared samples have been characterized with different characterization tools that include field emission scanning and high resolution transmission electron microscopy, Raman, Fourier transformed infrared as well as UV-Vis spectroscopy. The electrochemical performance of all the as prepared pure and hybrid samples have been studied in detail. It has been seen that the ternary hybrid shows efficient electrochemical performance with high value of specific capacitance with good stability even up to 2000 cycles. The superior performance of the hybrid samples can be attributed to the strong synergistic effect between the components resulting electron shuttling along PPy main chains and inter-chain raising built-in continuous conductive network. The ternary composite approach offers an effective solution to enhance the device performance of metal-oxide based supercapacitors for long cycling applications. These studies can well speculate the existence of another supercapacitor hybrid for the use in environment friendly electrode and thus a pollution free nature.

  7. Carbon-enhanced metal-poor stars in the SDSS-APOGEE data base

    Science.gov (United States)

    Kielty, C. L.; Venn, K. A.; Loewen, N. B.; Shetrone, M. D.; Placco, V. M.; Jahandar, F.; Mészáros, Sz.; Martell, S. L.

    2017-10-01

    We identify six new carbon-enhanced metal-poor (CEMP) stars ([C/Fe]>+0.7 and [Fe/H] data base following Data Release 12. These stars have chemical compositions typical of metal-poor halo stars, e.g. mean [α/Fe] = +0.24 ± 0.24, based on the APOGEE Stellar Parameters and Chemical Abundances Pipeline results. A lack of heavy-element spectral lines impedes further sub-classification of these CEMP stars, however, based on radial velocity (RV) scatter, we predict most are not CEMP-s stars which are typically found in binary systems. Only one object, 2M15312547+4220551, may be in a binary since it exhibits a scatter in its RV of 1.7 ± 0.6 km s-1 based on three visits over a 25.98 d baseline. Optical observations are now necessary to confirm the stellar parameters and low metallicities of these stars, to determine the heavy-element abundance ratios and improve the precision in the derived abundances, and to examine their CEMP sub-classifications.

  8. Enhanced durability of carbon nanotube grafted hierarchical ceramic microfiber-reinforced epoxy composites.

    Science.gov (United States)

    Krishnamurthy, Ajay; Hunston, Donald L; Forster, Amanda L; Natarajan, Bharath; Liotta, Andrew H; Wicks, Sunny S; Stutzman, Paul E; Wardle, Brian L; Liddle, J Alexander; Forster, Aaron M

    2017-12-01

    As carbon nanotube (CNT) infused hybrid composites are increasingly identified as next-generation aerospace materials, it is vital to evaluate their long-term structural performance under aging environments. In this work, the durability of hierarchical, aligned CNT grafted aluminoborosilicate microfiber-epoxy composites (CNT composites) are compared against baseline aluminoborosilicate composites (baseline composites), before and after immersion in water at 25 °C (hydro) and 60 °C (hydrothermal), for extended durations (90 d and 180 d). The addition of CNTs is found to reduce water diffusivities by approximately 1.5 times. The mechanical properties (bending strength and modulus) and the damage sensing capabilities (DC conductivity) of CNT composites remain intact regardless of exposure conditions. The baseline composites show significant loss of strength (44 %) after only 15 d of hydrothermal aging. This loss of mechanical strength is attributed to fiber-polymer interfacial debonding caused by accumulation of water at high temperatures. In situ acoustic and DC electrical measurements of hydrothermally aged CNT composites identify extensive stress-relieving micro-cracking and crack deflections that are absent in the aged baseline composites. These observations are supported by SEM images of the failed composite cross-sections that highlight secondary matrix toughening mechanisms in the form of CNT pullouts and fractures which enhance the service life of composites and maintain their properties under accelerated aging environments.

  9. Fabrication and test of adhesion enhanced flexible carbon nanotube transparent conducting films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hu; Geng, Hong-Zhang, E-mail: genghz@tjpu.edu.cn; Meng, Yan; Wang, Yan; Xu, Xiao-Bing; Ding, Er-Xiong; Gao, Jing; Chen, Li-Ting; Ma, Shuai

    2014-09-15

    Graphical abstract: Flexible TCFs were fabricated by a two-step spraying method using SWCNTs on pre-treated PET substrates and the adhesion was tested by ultrasonication resonance. - Highlights: • TCFs were fabricated using SWCNTs by a two-step spraying method. • PET substrates were pretreated with nitric acid to improve surface hydrophilicity. • Ultrasonication resonance method was introduced to test the adhesion of TCFs. • High adhesion SWCNT-TCFs with relatively low sheet resistance were obtained. - Abstract: This study introduced an innovative method to fabricate flexible transparent conducting films (TCFs) by spraying single-walled carbon nanotubes (SWCNTs) solution, dispersed by sodium dodecyl benzene sulfonate (SDBS), on polyethylene terephthalate (PET) substrate. The PET substrates were pretreated with nitric acid to improve the surface hydrophilicity. The films were spray deposited on the pretreated PET substrates in a two-step spray coating method. The film conductivity was further improved by nitric acid. As a convenient process, ultrasonication resonance method was applied to test the adhesion of TCFs. Comparing with the traditional preparation method, the adhesion of TCFs was enhanced and the mechanism was analyzed. The morphologies and thicknesses of TCFs were characterized by scanning electron microscopy and atomic force microscopy, while the Raman spectroscopy confirmed the structures of SWCNTs and the thickness changes of TCFs treated with different ultrasonication time.

  10. Excellent Field Emission Properties of Short Conical Carbon Nanotubes Prepared by Microwave Plasma Enhanced CVD Process

    Directory of Open Access Journals (Sweden)

    Vankar Vasant

    2007-01-01

    Full Text Available AbstractRandomly oriented short and low density conical carbon nanotubes (CNTs were prepared on Si substrates by tubular microwave plasma enhanced chemical vapor deposition process at relatively low temperature (350–550 °C by judiciously controlling the microwave power and growth time in C2H2 + NH3gas composition and Fe catalyst. Both length as well as density of the CNTs increased with increasing microwave power. CNTs consisted of regular conical compartments stacked in such a way that their outer diameter remained constant. Majority of the nanotubes had a sharp conical tip (5–20 nm while its other side was either open or had a cone/pear-shaped catalyst particle. The CNTs were highly crystalline and had many open edges on the outer surface, particularly near the joints of the two compartments. These films showed excellent field emission characteristics. The best emission was observed for a medium density film with the lowest turn-on and threshold fields of 1.0 and 2.10 V/μm, respectively. It is suggested that not only CNT tip but open edges on the body also act as active emission sites in the randomly oriented geometry of such periodic structures.

  11. Arbuscular Mycorrhizal Fungi and Glomalin Enhance Carbon Sequestration in Organic Farming Systems

    Science.gov (United States)

    Atmospheric carbon dioxide concentrations have increased nearly 100 ppm in the last 250 years. Soils may be able to mitigate this by sequestering carbon, but agricultural soils are often a source rather than a sink for carbon. The Rodale Institute’s Farming Systems Trial® (FST), initiated in 1981 ...

  12. Carbon Stable Isotope Values in Plankton and Mussels Reflect Changes in Carbonate Chemistry Associated with Nutrient Enhanced Net Production

    Science.gov (United States)

    Coastal ecosystems are inherently complex and potentially adaptive as they respond to changes in nutrient loads and climate. We documented the role that carbon stable isotope (δ13C) measurements could play in understanding that adaptation with a series of three Ecostat (i.e...

  13. Enhancing Carbon Reactivity in Mercury Control in Lignite-Fired Systems

    Energy Technology Data Exchange (ETDEWEB)

    Chad Wocken; Michael Holmes; John Pavlish; Jeffrey Thompson; Katie Brandt; Brandon Pavlish; Dennis Laudal; Kevin Galbreath; Michelle Olderbak

    2008-06-30

    This project was awarded through the U.S. Department of Energy (DOE) National Energy Technology Laboratory Program Solicitation DE-PS26-03NT41718-01. The Energy & Environmental Research Center (EERC) led a consortium-based effort to resolve mercury (Hg) control issues facing the lignite industry. The EERC team-the Electric Power Research Institute (EPRI); the URS Corporation; the Babcock & Wilcox Company; ADA-ES; Apogee; Basin Electric Power Cooperative; Otter Tail Power Company; Great River Energy; Texas Utilities; Montana-Dakota Utilities Co.; Minnkota Power Cooperative, Inc.; BNI Coal Ltd.; Dakota Westmoreland Corporation; the North American Coal Corporation; SaskPower; and the North Dakota Industrial Commission-demonstrated technologies that substantially enhanced the effectiveness of carbon sorbents to remove Hg from western fuel combustion gases and achieve a high level ({ge} 55% Hg removal) of cost-effective control. The results of this effort are applicable to virtually all utilities burning lignite and subbituminous coals in the United States and Canada. The enhancement processes were previously proven in pilot-scale and limited full-scale tests. Additional optimization testing continues on these enhancements. These four units included three lignite-fired units: Leland Olds Station Unit 1 (LOS1) and Stanton Station Unit 10 (SS10) near Stanton and Antelope Valley Station Unit 1 (AVS1) near Beulah and a subbituminous Powder River Basin (PRB)-fired unit: Stanton Station Unit 1 (SS1). This project was one of three conducted by the consortium under the DOE mercury program to systematically test Hg control technologies available for utilities burning lignite. The overall objective of the three projects was to field-test and verify options that may be applied cost-effectively by the lignite industry to reduce Hg emissions. The EERC, URS, and other team members tested sorbent injection technologies for plants equipped with electrostatic precipitators (ESPs) and

  14. Rate-based modelling and validation of a pilot absorber using MDEA enhanced with carbonic anhydrase (CA)

    DEFF Research Database (Denmark)

    Gaspar, Jozsef; Gladis, Arne; Woodley, John

    2017-01-01

    development. Post-combustion capture is a mature capture technology, however, to make it economically attractive, design of innovative solvents and process optimization is of crucial importance. An example for promising solvent is MDEA enhanced with carbonic anhydrase (CA), due to its fast kinetics and low......The great paradox of the 21st century is that we must meet the increasing global demand for energy and products while simultaneously mitigating the climate change. If both these criteria are to be met, carbon capture and storage is an imperative technology for sustainable energy infrastructure...

  15. MoS{sub 2}/cotton-derived carbon fibers with enhanced cyclic performance for sodium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiang [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Yang, Yan [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Liu, Jiangwen; Ouyang, Liuzhang; Liu, Jun; Hu, Renzong [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Yang, Lichun, E-mail: mslcyang@scut.edu.cn [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Zhu, Min [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China)

    2017-08-15

    Highlights: • MoS{sub 2} nanosheets vertically grow on cotton-derived carbon microfibers. • The carbon fibers facilitate charge transfer and structure stabilization. • The MoS{sub 2}/CDCFs exhibit enhanced cyclic performance for reversible Na{sup +} storage. - Abstract: Carbon fibers derived from bio-template are low cost and environmental benign, therefore have attracted much attention in energy storage materials. In this work, we successfully fabricated MoS{sub 2}/cotton-derived carbon fibers (MoS{sub 2}/CDCFs) via hydrothermal route followed by carbonization process. In the composite of MoS{sub 2}/CDCFs, MoS{sub 2} nanosheets vertically grow on the carbon fibers which offer fast ways for electron transfer and at the same time act as robust support to buffer the volume changes of MoS{sub 2} nanosheets during discharge/charge cycles. As anode materials for sodium-ion batteries, MoS{sub 2}/CDCFs exhibit good rate performance and markedly enhanced cyclic stability due to the conductive support of CDCFs. At a current density of 0.1 A g{sup −1}, the MoS{sub 2}/CDCFs-1 shows an initial reversible capacity of 504.9 mAh g{sup −1}, and maintains 444.5 mAh g{sup −1} after 50 cycles. Even when the current density increases to 0.5 A g{sup −1}, it maintains 323.1 mAh g{sup −1} after 150 cycles, which is much higher than the capacity retention of 149.6 mAh g{sup −1} for the bare MoS{sub 2} nanosheets. The improved electrochemical performance verifies the effective strategy of using cotton as carbon source to construct hierarchical composites for sodium-ion batteries.

  16. Microwave pyrolysis of oily sludge with activated carbon.

    Science.gov (United States)

    Chen, Yi-Rong

    2016-12-01

    The aim of this study is to explore catalytic microwave pyrolysis of crude oil storage tank sludge for fuels using granular activated carbon (GAC) as a catalyst. The effect of GAC loading on the yield of pyrolysis products was also investigated. Heating rate of oily sludge and yield of microwave pyrolysis products such as oil and fuel gas was found to depend on the ratio of GAC to oily sludge. The optimal GAC loading was found to be 10%, while much smaller and larger feed sizes adversely influenced production. During oily sludge pyrolysis, a maximum oil yield of 77.5% was achieved. Pyrolytic oils with high concentrations of diesel oil and gasoline (about 70 wt% in the pyrolytic oil) were obtained. The leaching of heavy metals, such as Cr, As and Pb, was also suppressed in the solid residue after pyrolysis. This technique provides advantages such as harmless treatment of oily sludge and substantial reduction in the consumption of energy, time and cost.

  17. Enhanced microwave absorption properties and mechanism of core/shell structured magnetic nanoparticles/carbon-based nanohybrids

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Xiaosi, E-mail: sci.xsqi@gzu.edu.cn [Physics Department, Guizhou University, Guiyang 550025 (China); Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Hu, Qi; Xu, Jianle; Xie, Ren; Bai, Zhongchen; Jiang, Yang; Qin, Shuijie [Physics Department, Guizhou University, Guiyang 550025 (China); Zhong, Wei, E-mail: wzhong@nju.edu.cn [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China); Du, Youwei [Nanjing National Laboratory of Microstructures and Jiangsu Provincial Laboratory for NanoTechnology, Nanjing University, Nanjing 210093 (China)

    2016-09-15

    Graphical abstract: In the article, core/shell Fe{sub 3}O{sub 4}/C, Fe/helical carbon nanotubes were synthesized selectively. The results indicated that the optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possibly enhanced microwave absorption mechanisms were also discussed in detail. - Highlights: • An efficient scheme was designed to synthesize core/shell magnetic nanoparticles/carbon-based hybrids. • By controlling the temperature, different categories of core/shell nanohybrids were synthesized. • The obtained Fe/CNT hybrid exhibits enhanced microwave absorption property. • Enhanced microwave absorbing mechanism was discussed in detail. - Abstract: An efficient scheme was designed to selectively synthesize different categories of core/shell structured magnetic nanoparticles/carbon-based nanohybrids such as Fe{sub 3}O{sub 4}/C and Fe/helical carbon nanotubes (HCNTs) through the decomposition of acetylene directly over Fe{sub 2}O{sub 3} nanotubes by controlling the pyrolysis temperature. The measured electromagnetic parameters indicated that the Fe/HCNT nanohybrids exhibited enhanced microwave absorption properties, which may be related to their special structures. The optimum reflection loss (RL) could reach −47.1 dB at 17.39 GHz with a matching thickness of 1.39 mm. The absorption bandwidth with the RL values below −20 dB was up to 11.59 GHz. Moreover, based on the obtained results, the possible enhanced EM absorption mechanisms were also discussed in detail. The results show excellent microwave absorption materials that are lightweight, have strong absorption and a wide absorption frequency band may be realized in these nanohybrids.

  18. Effects of feed gas composition and catalyst thickness on carbon nanotube and nanofiber synthesis by plasma enhanced chemical vapor deposition.

    Science.gov (United States)

    Garg, R K; Kim, S S; Hash, D B; Gore, J P; Fisher, T S

    2008-06-01

    Many engineering applications require carbon nanotubes with specific characteristics such as wall structure, chirality and alignment. However, precise control of nanotube properties grown to application specifications remains a significant challenge. Plasma-enhanced chemical vapor deposition (PECVD) offers a variety of advantages in the synthesis of carbon nanotubes in that several important synthesis parameters can be controlled independently. This paper reports an experimental study of the effects of reacting gas composition (percentage methane in hydrogen) and catalyst film thickness on carbon nanotube (CNT) growth and a computational study of gas-phase composition for the inlet conditions of experimentally observed carbon nanotube growth using different chemical reaction mechanisms. The simulations seek to explain the observed effects of reacting gas composition and to identify the precursors for CNT formation. The experimental results indicate that gas-phase composition significantly affects the synthesized material, which is shown to be randomly aligned nanotube and nanofiber mats for relatively methane-rich inlet gas mixtures and non-tubular carbon for methane-lean incoming mixtures. The simulation results suggest that inlet methane-hydrogen mixture coverts to an acetylene-methane-hydrogen mixture with minor amounts of ethylene, hydrogen atom, and methyl radical. Acetylene appears to be the indicator species for solid carbon formation. The simulations also show that inlet methane-hydrogen mixture does not produce enough gas-phase precursors needed to form quality CNTs below 5% CH4 concentrations in the inlet stream.

  19. Hybrid membrane using polyethersulfone-modification of multiwalled carbon nanotubes with silane agent to enhance high performance oxygen separation

    Directory of Open Access Journals (Sweden)

    Tutuk Djoko Kusworo

    2014-04-01

    Full Text Available Mixed matrix membrane comprising carbon nanotubes embedded in polymer matrix have become one of the emerging technologies. This study was investigated in order to study the effect of silane agent modification towards carbon nanotubes (CNT surface at different concentration on oxygen enrichment performances of asymmetric mixed matrix membrane. The modified carbon nanotubes were prepared by treating the carbon nanotubes with chemical modification using Dynasylan Ameo (DA silane agent to allow PES chains to be grafted on carbon nanotubes surface. The results from the FESEM, DSC and FTIR analysis confirmed that chemical modification on carbon nanotubes surface had taken place. Sieve-in-a-cage’ morphology observed shows the poor adhesion between polymer and unmodified CNT. The gas separation performance of the asymmetric flat sheet mixed matrix membranes with modified CNT were relatively higher compared to the unmodified CNT. Hence, coated hollow fiber mixed matrix membrane with chemical modification on CNT surface using (3-aminopropyl-triethoxy methyl silane agent can potentially enhance the gas separation performance of O2 and N2.

  20. Enhanced sputtering yields of carbon due to accumulation of low-energy Xe ions

    Science.gov (United States)

    Kenmotsu, T.; Wada, M.; Hyakutake, T.; Muramoto, T.; Nishida, M.

    2009-05-01

    We have calculated the sputtering yields of carbon and molybdenum under xenon ion bombardment by a Monte Carlo code ACAT which simulates binary collision events in solids. The yields of carbon calculated with ACAT differ from the experimental data below the threshold energy predicted from the semi-empirical formula proposed by Yamamura and Tawara. Meanwhile, the results of ACAT with 14% xenon atoms retained in graphite are in good agreement with the experimental data and the xenon retention in carbon plays an important role in reducing the threshold energy for carbon sputtering. In order to estimate the experimental sputtering yields of carbon, a simplified formula is proposed in the frame of the semi-empirical formula. The formula predicts the yield curve close to the reported sputtering yields of carbon for the condition that carbon target retains 14% xenon atoms.