The effect of double steps heat treatment on the microstructure of nanostructure bainitic medium carbon steels

Science.gov (United States)

Foughani, Milad; Kolahi, Alireza; Palizdar, Yahya

2018-01-01

Nowadays, Nano structure bainitic steel have attracted attention mostly because of its special mechanical properties such as high tensile strength, hardness, appropriate toughness and low manufacturing cost. The main concern for the mass production of this type of steels is prolong austempering process which increases the production costs as well as time. In this research, in order to accelerate the bainitic transformation and decrease the production time, a medium carbon steel has been prepared and two steps austempering process was employed to prevent the bainite laths thickening. The Samples were austenetized at 1000°C for 15 min and were kept in the salt bath between 1 - 12 hours at 290°C in one step and between 1 - 12 hours at the temperature range of 250°C - 300°C in two steps bainite transformation. The obtained micro structures were studied by the optical and scanning electron microscopy (FESEM) and the mechanical properties were investigated by using tensile and hardness tests. The results show that the two steps austempering process and lower carbon concentration lead to lower austempering time as well as the formation of more stable retained austenite and nanostructured bainite lath which results in higher mechanical properties.

High-performance all-solid-state flexible supercapacitors based on two-step activated carbon cloth

Science.gov (United States)

Jiang, Shulan; Shi, Tielin; Zhan, Xiaobin; Long, Hu; Xi, Shuang; Hu, Hao; Tang, Zirong

2014-12-01

A simple and effective strategy is proposed to activate carbon cloth for the fabrication of flexible and high-performance supercapacitors. Firstly, the carbon cloth surface is exfoliated as nanotextures through wet chemical treatment, then an annealing process is applied at H2/N2 atmosphere to reduce the surface oxygen functional groups which are mainly introduced from the first step. The activated carbon cloth electrode shows excellent wettablity, large surface area and delivers remarkable electrochemical performance. A maximum areal capacitance of 485.64 mF cm-2 at the current density of 2 mA cm-2 is achieved for the activated carbon cloth electrode, which is considerably larger than the resported results for carbon cloth. Furthermore, the flexible all-solid-state supercapacitor, which is fabricated based on the activated carbon cloth electrodes, shows high areal capacitance, superior cycling stability as well as stable electrochemical performance even under constant bending or twisting conditions. An areal capacitance of 161.28 mF cm-2 is achieved at the current density of 12.5 mA cm-2, and 104% of its initial capacitance is retained after 30,000 charging/discharging cycles. This study would also provide an effective way to boost devices' electrochemical performance by accommodating other active materials on the activated carbon cloth.

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

International Nuclear Information System (INIS)

1992-01-01

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

Lipids Reprogram Metabolism to Become a Major Carbon Source for Histone Acetylation

DEFF Research Database (Denmark)

McDonnell, Eoin; Crown, Scott B; Fox, Douglas B

2016-01-01

Cells integrate nutrient sensing and metabolism to coordinate proper cellular responses to a particular nutrient source. For example, glucose drives a gene expression program characterized by activating genes involved in its metabolism, in part by increasing glucose-derived histone acetylation....... Here, we find that lipid-derived acetyl-CoA is a major source of carbon for histone acetylation. Using (13)C-carbon tracing combined with acetyl-proteomics, we show that up to 90% of acetylation on certain histone lysines can be derived from fatty acid carbon, even in the presence of excess glucose...

Organic carbon degradation in arctic marine sediments, Svalbard: A comparison of initial and terminal steps

DEFF Research Database (Denmark)

Arnosti, C.; Jørgensen, BB

2006-01-01

carbohydrate concentrations were comparable to those measured in more temperate sediments, and likely comprise a considerable fraction of porewater dissolved organic carbon. A comparison of dissolved carbohydrate inventories with hydrolysis and sulfate reduction rates suggests that the turnover of carbon......Degradation of marine organic matter under anoxic conditions involves microbial communities working in concert to remineralize complex substrates to CO2. In order to investigate the coupling between the initial and terminal steps of this sequence in permanently cold sediments, rates...... of extracellular enzymatic hydrolysis and sulfate reduction were measured in parallel cores collected from 5 fjords on the west and northwest coast of Svalbard, in the high Arctic. Inventories of total dissolved carbohydrates were also measured in order to evaluate their potential role in carbon turnover...

Production and characterization of carbon nano colloid via one-step electrochemical method

Energy Technology Data Exchange (ETDEWEB)

Kim, Doohyun; Hwang, Yujin; Cheong, Seong Ir; Lee, Jae Keun [Pusan National University, Department of Mechanical Engineering (Korea, Republic of); Hong, Daeseung; Moon, Seongyong [N-BARO TECH CO., LTD, Institute of SamchangTsinghua Nano Application (Korea, Republic of); Lee, Jung Eun [Pusan National University, Industrial Liaison Innovation Cluster (Korea, Republic of); Kim, Soo H., E-mail: sookim@pusan.ac.k [Pusan National University, Department of Nanosystem and Nanoprocess Engineering (Korea, Republic of)

2008-10-15

We present a one-step electrochemical method to produce water-based stable carbon nano colloid (CNC) without adding any surfactants at the room temperature. The physical, chemical, and thermal properties of CNC prepared were characterized by using various techniques, such as particle size analyzer, zeta potential meter, TEM, XRD, FT-IR, turbidity meter, viscometer, and transient hot-wire method. The average primary size of the suspended spherical-shaped nanoparticles in the CNC was found to be {approx}15 nm in diameter. The thermal conductivity of CNC compared with that of water was observed to increase up to {approx}14% with the CNC concentration of {approx}4.2 wt%. The CNC prepared in this study was considerably stable over the period of 600 h. With the assistance of FT-IR spectroscopy analysis, we confirmed the presence of carboxyl group (i.e., O-H stretching (3,458 cm{sup -1}) and C=O stretching (1,712 cm{sup -1})) formed in the outer atomic layer of carbon nanoparticles, which (i) made the carbon particles hydrophilic and (ii) prevented the aggregation among primary nanoparticles by increasing the magnitude of zeta potential over the long period.

Production and characterization of carbon nano colloid via one-step electrochemical method

International Nuclear Information System (INIS)

Kim, Doohyun; Hwang, Yujin; Cheong, Seong Ir; Lee, Jae Keun; Hong, Daeseung; Moon, Seongyong; Lee, Jung Eun; Kim, Soo H.

2008-01-01

We present a one-step electrochemical method to produce water-based stable carbon nano colloid (CNC) without adding any surfactants at the room temperature. The physical, chemical, and thermal properties of CNC prepared were characterized by using various techniques, such as particle size analyzer, zeta potential meter, TEM, XRD, FT-IR, turbidity meter, viscometer, and transient hot-wire method. The average primary size of the suspended spherical-shaped nanoparticles in the CNC was found to be ∼15 nm in diameter. The thermal conductivity of CNC compared with that of water was observed to increase up to ∼14% with the CNC concentration of ∼4.2 wt%. The CNC prepared in this study was considerably stable over the period of 600 h. With the assistance of FT-IR spectroscopy analysis, we confirmed the presence of carboxyl group (i.e., O-H stretching (3,458 cm -1 ) and C=O stretching (1,712 cm -1 )) formed in the outer atomic layer of carbon nanoparticles, which (i) made the carbon particles hydrophilic and (ii) prevented the aggregation among primary nanoparticles by increasing the magnitude of zeta potential over the long period.

Synthesis of highly aligned carbon nanotubes by one-step liquid-phase process: Effects of carbon sources on morphology of carbon nanotubes

Science.gov (United States)

Yamagiwa, Kiyofumi; Kuwano, Jun

2017-06-01

This paper describes a unique and innovative synthesis technique for carbon nanotubes (CNTs) by a one-step liquid-phase process under ambient pressure. Vertically aligned multi-walled CNT arrays with a maximum height of 100 µm are prepared on stainless steel substrates, which are submerged and electrically heated in straight-chain primary alcohols with n C = 1-4 (n C: number of C atoms in the molecule) containing an appropriate amount of cobalt-based organometallic complex as a catalyst precursor. Structural isomers of butanol were also used for the synthesis to examine the effects of structural factors on the morphology of the deposited products. Notably, 2-methyl-2-propanol, which is a tertiary alcohol, produced only a small amount of low-crystallinity carbonaceous deposits, whereas vertically aligned CNTs were grown from the other isomers of butanol. These results suggest that the presence or absence of β-hydrogen in the molecular structure is a key factor for understanding the dissociation behavior of the carbon source molecules on the catalyst.

Amperometric sensor for ethanol based on one-step electropolymerization of thionine-carbon nanofiber nanocomposite containing alcohol oxidase.

Science.gov (United States)

Wu, Lina; McIntosh, Mike; Zhang, Xueji; Ju, Huangxian

2007-12-15

Thionine had strong interaction with carbon nanofiber (CNF) and was used in the non-covalent functionalization of carbon nanofiber for the preparation of stable thionine-CNF nanocomposite with good dispersion. With a simple one-step electrochemical polymerization of thionine-CNF nanocomposite and alcohol oxidase (AOD), a stable poly(thionine)-CNF/AOD biocomposite film was formed on electrode surface. Based on the excellent catalytic activity of the biocomposite film toward reduction of dissolved oxygen, a sensitive ethanol biosensor was proposed. The ethanol biosensor could monitor ethanol ranging from 2.0 to 252 microM with a detection limit of 1.7 microM. It displayed a rapid response, an expanded linear response range as well as excellent reproducibility and stability. The combination of catalytic activity of CNF and the promising feature of the biocomposite with one-step non-manual technique favored the sensitive determination of ethanol with improved analytical capabilities.

Highly efficient one-step synthesis of carbon encapsulated nanocrystals by the oxidation of metal π-complexes

Science.gov (United States)

Liu, Boyang; Shao, Yingfeng; Xiang, Xin; Zhang, Fuhua; Yan, Shengchang; Li, Wenge

2017-08-01

Various carbon encapsulated nanocrystals, including MnS and MnO, Cr2O3, MoO2, Fe7S8 and Fe3O4, and ZrO2, are prepared in one step and in situ by a simple and highly efficient synthesis approach. The nanocrystals have an equiaxed morphology and a median size smaller than 30 nm. Tens and hundreds of these nanocrystals are entirely encapsulated by a wormlike amorphous carbon shell. The formation of a core-shell structure depends on the strongly exothermic reaction of metal π-complexes with ammonium persulfate in an autoclave at below 200 °C. During the oxidation process, the generated significant amounts of heat will destroy the molecular structure of the metal π-complex and cleave the ligands into small carbon fragments, which further transform into an amorphous carbon shell. The central metal atoms are oxidized to metal oxide/sulfide nanocrystals. The formation of a core-shell structure is independent of the numbers of ligands and carbon atoms as well as the metal types, implying that any metal π-complex can serve as a precursor and that various carbon encapsulated nanocrystals can be synthesized by this method.

One-step sub-10 μm patterning of carbon-nanotube thin films for transparent conductor applications.

Science.gov (United States)

Fukaya, Norihiro; Kim, Dong Young; Kishimoto, Shigeru; Noda, Suguru; Ohno, Yutaka

2014-04-22

We propose a technique for one-step micropatterning of as-grown carbon-nanotube films on a plastic substrate with sub-10 μm resolution on the basis of the dry transfer process. By utilizing this technique, we demonstrated the novel high-performance flexible carbon-nanotube transparent conductive film with a microgrid structure, which enabled improvement of the performance over the trade-off between the sheet resistance and transmittance of a conventional uniform carbon-nanotube film. The sheet resistance was reduced by 46% at its maximum by adding the microgrid, leading to a value of 53 Ω/sq at a transmittance of 80%. We also demonstrated easy fabrication of multitouch projected capacitive sensors with 12 × 12 electrodes. The technique is quite promising for energy-saving production of transparent conductor devices with 100% material utilization.

Variation in carbon stocks on different slope aspects in seven major ...

Indian Academy of Sciences (India)

The present study was undertaken in seven major forest types of temperate zone (1500 m a.s.l. to 3100 m a.s.l.) of Garhwal Himalaya to understand the effect of slope aspects on carbon (C) density and make recommendations for forest management based on priorities for C conservation/sequestration. We assessed soil ...

Two Step Wittig/Dihydroxylation Synthetic Route to Higher Sugars

DEFF Research Database (Denmark)

Jørgensen, Morten; Madsen, Robert

1999-01-01

Higher carbon sugars are obtained by a two carbon, two step chain elongation of aldoses involving first a Wittig reaction and then an osmium tetroxide catalyzed dihydroxylation......Higher carbon sugars are obtained by a two carbon, two step chain elongation of aldoses involving first a Wittig reaction and then an osmium tetroxide catalyzed dihydroxylation...

One-step synthesis of 2D-layered carbon wrapped transition metal nitrides from transition metal carbides (MXenes) for supercapacitors with ultrahigh cycling stability.

Science.gov (United States)

Yuan, Wenyu; Cheng, Laifei; Wu, Heng; Zhang, Yani; Lv, Shilin; Guo, Xiaohui

2018-03-13

A novel one-step method to synthesize 2D carbon wrapped TiN (C@TiN) was proposed via using 2D metal carbides (MXenes) as precursors. This study provides a novel approach to synthesize carbon wrapped metal nitrides.

THE DISTRIBUTION OF ORGANIC CARBON IN MAJOR COMPONENTS OF FORESTS LOCATED IN FIVE LIFE ZONES OF VENEZUELA

Science.gov (United States)

One of the major uncertainties concerning the role of tropical forests in the global carbon cycle is the lack of adequate data on the carbon content of all their components. The goal of this study was to contribute to filling this data gap by estimating the quantity of carbon in ...

A two-step process of nitrous oxide before carbon dioxide for humanely euthanizing piglets: on-farm trials

Science.gov (United States)

The current methods of euthanizing neonatal piglets are raising concerns from the public and scientists. Our experiment tests the use of a two-step euthanasia method using nitrous oxide (N2O) for six minutes and then carbon dioxide (CO2) as a more humane way to euthanize piglets compared to just usi...

Evaluation of single-step steam pyrolysis-activated carbons

African Journals Online (AJOL)

Mgina

Activated carbon has been widely used worldwide as an effective filtration or adsorption ... of producing activated carbon (AC) from local agroforestry residues by ..... impurities from waste water. .... Production of granular activated carbon.

Seven steps to curb global warming

International Nuclear Information System (INIS)

Mathews, John

2007-01-01

Based on best current estimates that the world needs to reduce global carbon dioxide emissions by 70% by 2050, and that there is at best a 10-year window of opportunity available to initiate the enormous changes needed, this paper proposes a set of seven self-contained steps that can be taken at a global level to tackle the problem with some prospect of success. The steps are self-financing and practicable, in that they are based on existing technologies. They involve agreement to create a new international agency charged with formulating and policing a global carbon pricing regime; a complementary step involving global monitoring of greenhouse gas emissions utilizing satellite resources; taking steps to compensate developing countries for preserving rainforest as carbon sinks; the dismantling of newly created trade barriers holding back global trade in biofuels; global promotion of a transition to renewable sources of electricity through facilitation of grid interconnections with independent power producers; a global moratorium on the building of new coal-fired power stations; and recycling of carbon revenues to promote uptake of renewable energy sources in developing countries, particularly Brazil, India and China. Taken as a group, it is argued that these steps are both necessary and sufficient. They call for institutional innovations at a global level that are politically difficult but feasible, given the magnitude of the problems addressed

One-step synthesis of solid state luminescent carbon-based silica nanohybrids for imaging of latent fingerprints

Science.gov (United States)

Li, Feng; Li, Hongren; Cui, Tianfang

2017-11-01

Fluorescent carbon-based nanomaterials(CNs) with tunable visible emission are biocompatible, environment friendly and most suitable for various biomedical applications. Despite the successes in preparing strongly fluorescent CNs, preserving the luminescence in solid materials is still challenging because of the serious emission quenching of CNs in solid state materials. In this work, fluorescent carbon and silica nanohybrids (SiCNHs) were synthesized via a simple one-step hydrothermal approach by carbonizing sodium citrate and (3-aminopropyl)triethoxysilane(APTES), and hydrolysis of tetraethyl orthosilicate(TEOS). The resultant SiCNs were characterized through X-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The SiCNs exhibited strong fluorescence in both aqueous and solid states. The luminescent solid state SiCNs power were successfully used as a fluorescent labeling material for enhanced imaging of latent fingerprints(LFPs) on single background colour and multi-coloured surfaces substrates in forensic science for individual identification.

A Nanopore-Structured Nitrogen-Doped Biocarbon Electrocatalyst for Oxygen Reduction from Two-Step Carbonization of Lemna minor Biomass

Science.gov (United States)

Guo, Chaozhong; Li, Zhongbin; Niu, Lidan; Liao, Wenli; Sun, Lingtao; Wen, Bixia; Nie, Yunqing; Cheng, Jing; Chen, Changguo

2016-05-01

So far, the development of highly active and stable carbon-based electrocatalysts for oxygen reduction reaction (ORR) to replace commercial Pt/C catalyst is a hot topic. In this study, a new nanoporous nitrogen-doped carbon material was facilely designed by two-step pyrolysis of the renewable Lemna minor enriched in crude protein under a nitrogen atmosphere. Electrochemical measurements show that the onset potential for ORR on this carbon material is around 0.93 V (versus reversible hydrogen electrode), slightly lower than that on the Pt/C catalyst, but its cycling stability is higher compared to the Pt/C catalyst in an alkaline medium. Besides, the ORR at this catalyst approaches to a four-electron transfer pathway. The obtained ORR performance can be basically attributed to the formation of high contents of pyridinic and graphitic nitrogen atoms inside this catalyst. Thus, this work opens up the path in the ORR catalysis for the design of nitrogen-doped carbon materials utilizing aquatic plants as starting precursors.

A carbon in molten carbonate anode model for a direct carbon fuel cell

Energy Technology Data Exchange (ETDEWEB)

Li Hongjiao; Liu Qinghua [Tianjin Key Laboratory of Catalysis Science and Technology, School of Chemical Engineering, Tianjin University, Weijing Road 92, Tianjin 300072 (China); State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Weijing Road 92, Tianjin 300072 (China); Li Yongdan, E-mail: ydli@tju.edu.c [Tianjin Key Laboratory of Catalysis Science and Technology, School of Chemical Engineering, Tianjin University, Weijing Road 92, Tianjin 300072 (China); State Key Laboratory for Chemical Engineering (Tianjin University), School of Chemical Engineering, Tianjin University, Weijing Road 92, Tianjin 300072 (China)

2010-02-15

The electrochemical oxidation of carbon at the anode of a direct carbon fuel cell (DCFC) includes charge transfer steps and chemical steps. A microstructural model of carbon particle is built, in which perfect graphene stacks are taken as the basic building blocks of carbon. A modified mechanism taking account of the irreversibility of the process and supposing that the electrochemical oxidation of carbon takes place only at the edges of the graphene sheets is proposed. A Tafel type overall rate equation is deduced along with expressions of exchange current density (j{sub 0}) and activation polarization (eta{sub act}). The performance of carbon black and graphite as the fuel of DCFC is examined. It has been found that j{sub 0} is in the range of 0.10-6.12 mA cm{sup -2} at 923-1123 K and eta{sub act} is in the range of 0.024-0.28 V at 923-1123 K with current density in 10-120 mA cm{sup -2}. Analysis of the j{sub 0}, eta{sub act} values and the product composition reveals that the charge transfer steps as well as the oxygen ion absorption steps are both important for the reaction rate. The activity of the carbon material with respect to atom location is introduced to the open circuit potential difference (OCP) calculation with Nernst equation.

Effects of carbon source and carbon content on electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C prepared by one-step solid-state reaction

Energy Technology Data Exchange (ETDEWEB)

Hu Xuebu [College of Chemistry and Materials Science, Sichuan Normal University, Chengdu, Sichuan 610066 (China); Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China); Lin Ziji [China National Quality Supervision and Inspection Center for Alcoholic Beverage Products and Processed Food, Luzhou, Sichuan 646100 (China); Yang Kerun [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China); Hua, Yongjian [China Aviation Lithium Battery Co. Ltd., Luoyang, Henan 471009 (China); Deng Zhenghua, E-mail: zhdeng@cioc.ac.cn [Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, Sichuan 610041 (China)

2011-05-30

Highlights: > A simple route to prepare the Li{sub 4}Ti{sub 5}O{sub 12}/C by one-step solid-state reaction. > Carbon source and carbon content are two important factors on the electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C. > As-prepared Li{sub 4}Ti{sub 5}O{sub 12}/C under optimized conditions shows excellent electrochemical performances. - Abstract: Li{sub 4}Ti{sub 5}O{sub 12}/C composites were synthesized by one-step solid-state reaction method using four commonly used organic compounds or organic polymers as carbon source, i.e., polyacrylate acid (PAA), citric acid (CA), maleic acid (MA) and polyvinyl alcohol (PVA). The physical characteristics of Li{sub 4}Ti{sub 5}O{sub 12}/C composites were investigated by X-ray diffraction, electron microscopy, Raman spectroscopy, particle size distribution and thermogravimetry-derivative thermogravimetry techniques. Their electrochemical properties were characterized by cyclic voltammograms, electrochemical impedance spectra, constant current charge-discharge and rate charge-discharge. These analyses indicated that the carbon source and carbon content have a great effect on the physical and electrochemical performances of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. An ideal carbon source and appropriate carbon content effectively improved the electrical contact between the Li{sub 4}Ti{sub 5}O{sub 12} particles, which enhanced the discharge capacity and rate capability of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. PAA was the best carbon source for the synthesis of Li{sub 4}Ti{sub 5}O{sub 12}/C composites. When the carbon content was 3.49 wt.% (LiOH.H{sub 2}O/PAA molar ratio of 1), as-prepared Li{sub 4}Ti{sub 5}O{sub 12}/C showed the maximum discharge capacity. At 0.2 C, initial capacity of the optimized sample was 168.6 mAh g{sup -1} with capacity loss of 2.8% after 50 cycles. At 8 and 10 C, it showed discharge capacities of 143.5 and 132.7 mAh g{sup -1}, with capacity loss of 8.7 and 9.9% after 50 cycles

One-Step Synthesis of Microporous Carbon Monoliths Derived from Biomass with High Nitrogen Doping Content for Highly Selective CO2 Capture

OpenAIRE

Geng, Zhen; Xiao, Qiangfeng; Lv, Hong; Li, Bing; Wu, Haobin; Lu, Yunfeng; Zhang, Cunman

2016-01-01

The one-step synthesis method of nitrogen doped microporous carbon monoliths derived from biomass with high-efficiency is developed using a novel ammonia (NH3)-assisted activation process, where NH3 serves as both activating agent and nitrogen source. Both pore forming and nitrogen doping simultaneously proceed during the process, obviously superior to conventional chemical activation. The as-prepared nitrogen-doped active carbons exhibit rich micropores with high surface area and high nitrog...

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

International Nuclear Information System (INIS)

Zhang Chengyu; Qiao Shengru; Yang Zhimao; Ding Bingjun

2007-01-01

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

Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

Energy Technology Data Exchange (ETDEWEB)

Li, H.Y.; Lu, X.W. [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, X.C.; Min, Y.A. [School of Materials Science and Engineering, Shanghai University, Shanghai 200240 (China); Jin, X.J., E-mail: jin@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-09-15

Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus {epsilon}-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

Bainitic transformation during the two-step quenching and partitioning process in a medium carbon steel containing silicon

International Nuclear Information System (INIS)

Li, H.Y.; Lu, X.W.; Wu, X.C.; Min, Y.A.; Jin, X.J.

2010-01-01

Research highlights: In this paper, SEM and TEM were used to characterize microstructure of Q and P steels with different partitioning time at 300 deg. C. The interesting phenomena were discovered and discussed: 1.Lower bainite (bainitic ferrite plus ε-carbide) rather than carbide-free bainite was observed during partitioning process. 2.The mechanical properties of Q and P steels can be tailored and adjusted through balance volume fraction of retained austenite and lower bainite during partitioning process. 3.The final amount of austenite was influenced by the transformation kinetics of lower bainite during partitioning process. According to the analysis, it can be concluded that associated with carbon partitioning from martensite to austenite, lower bainite transformation inevitably occurred. More importantly, lower bainite transformation seriously affected the mechanical properties of Q and P steels and final amount of austenite. - Abstract: A study of 40SiMnNiCr steel subjected to a two-step quenching and partitioning process (Q and P) is presented. The result suggests that strength variation of Q and P steels during the two-step Q and P process was a cumulative effect of increase of retained austenite fraction, decrease of carbon supersaturation of virgin martensite, and particularly much of lower bainite formation. A trade-off between high strength and good ductility of two-step Q and P steels can be tailored and adjusted by controlling lower bainite fraction. The final amount of austenite was influenced by the transformation kinetics of lower bainite during the partitioning process.

Computational Prediction of Excited-State Carbon Tunneling in the Two Steps of Triplet Zimmerman Di-π-Methane Rearrangement.

Science.gov (United States)

Li, Xin; Liao, Tao; Chung, Lung Wa

2017-11-22

The photoinduced Zimmerman di-π-methane (DPM) rearrangement of polycyclic molecules to form synthetically useful cyclopropane derivatives was found experimentally to proceed in a triplet excited state. We have applied state-of-the-art quantum mechanical methods, including M06-2X, DLPNO-CCSD(T) and variational transition-state theory with multidimensional tunneling corrections, to an investigation of the reaction rates of the two steps in the triplet DPM rearrangement of dibenzobarrelene, benzobarrelene and barrelene. This study predicts a high probability of carbon tunneling in regions around the two consecutive transition states at 200-300 K, and an enhancement in the rates by 104-276/35-67% with carbon tunneling at 200/300 K. The Arrhenius plots of the rate constants were found to be curved at low temperatures. Moreover, the computed 12 C/ 13 C kinetic isotope effects were affected significantly by carbon tunneling and temperature. Our predictions of electronically excited-state carbon tunneling and two consecutive carbon tunneling are unprecedented. Heavy-atom tunneling in some photoinduced reactions with reactive intermediates and narrow barriers can be potentially observed at relatively low temperature in experiments.

Sintering uranium oxide using a preheating step

International Nuclear Information System (INIS)

Jensen, N.J.; Nivas, Y.; Packard, D.R.

1977-01-01

Compacted pellets of uranium oxide or uranium oxide with one or more additives are heated in a kiln in a process having a preheating step, a sintering step, a reduction step, and a cooling step in a controlled atmosphere. The process is practiced to give a range of temperature and atmosphere conditions for obtaining optimum fluoride removal from the compacted pellets along with optimum sintering in a single process. The preheating step of this process is conducted in a temperature range of about 600 0 to about 900 0 C and the pellets are held for at least twenty min, and preferably about 60 min, in an atmosphere having a composition in the range of about 10 to about 75 vol % hydrogen with the balance being carbon dioxide. The sintering step is conducted at a temperature in the range of about 900 0 C to 1500 0 C in the presence of an atmosphere having a composition in the range of about 0.5 to about 90 vol % hydrogen with the balance being carbon dioxide. The reduction step reduces the oxygen to metal ratio of the pellets to a range of about 1.98 to 2.10:1 and this is accomplished by gradually cooling the pellets for about 30 to about 120 min from the temperature of the sintering step to about 1100 0 C in an atmosphere of about 10 to 90 vol % hydrogen with the balance being carbon dioxide. Thereafter the pellets are cooled to about 100 0 C under a protective atmosphere, and in one preferred practice the same atmosphere used in the reduction step is used in the cooling step. The preheating, sintering and reduction steps may also be conducted with their respective atmospheres having an initial additional component of water vapor and the water vapor can comprise up to about 20 vol %

The carbon market: major operational carbon funds and financed projects

International Nuclear Information System (INIS)

Markandya, A.; Nobili, V.

2008-01-01

The flexible mechanisms envisaged by the Kyoto Protocol have led gradually to a global carbon market that has become very appetizing for companies operating in the sector. Financial instruments such as carbon funds, and investments in greenhouse-gas-reduction projects, now operate at the international level, counting on the development of new technologies and energy efficiency, and contributing to sustainable development in the countries that host the projects [it

Major role of microbes in carbon fluxes during Austral winter in the Southern Drake Passage.

Directory of Open Access Journals (Sweden)

Maura Manganelli

Full Text Available Carbon cycling in Southern Ocean is a major issue in climate change, hence the need to understand the role of biota in the regulation of carbon fixation and cycling. Southern Ocean is a heterogeneous system, characterized by a strong seasonality, due to long dark winter. Yet, currently little is known about biogeochemical dynamics during this season, particularly in the deeper part of the ocean. We studied bacterial communities and processes in summer and winter cruises in the southern Drake Passage. Here we show that in winter, when the primary production is greatly reduced, Bacteria and Archaea become the major producers of biogenic particles, at the expense of dissolved organic carbon drawdown. Heterotrophic production and chemoautotrophic CO(2 fixation rates were substantial, also in deep water, and bacterial populations were controlled by protists and viruses. A dynamic food web is also consistent with the observed temporal and spatial variations in archaeal and bacterial communities that might exploit various niches. Thus, Southern Ocean microbial loop may substantially maintain a wintertime food web and system respiration at the expense of summer produced DOC as well as regenerate nutrients and iron. Our findings have important implications for Southern Ocean ecosystem functioning and carbon cycle and its manipulation by iron enrichment to achieve net sequestration of atmospheric CO(2.

The Electrochemical Behavior of Carbon Fiber Microelectrodes Modified with Carbon Nanotubes Using a Two-Step Electroless Plating/Chemical Vapor Deposition Process

Directory of Open Access Journals (Sweden)

Longsheng Lu

2017-03-01

Full Text Available Carbon fiber microelectrode (CFME has been extensively applied in the biosensor and chemical sensor domains. In order to improve the electrochemical activity and sensitivity of the CFME, a new CFME modified with carbon nanotubes (CNTs, denoted as CNTs/CFME, was fabricated and investigated. First, carbon fiber (CF monofilaments grafted with CNTs (simplified as CNTs/CFs were fabricated in two key steps: (i nickel electroless plating, followed by (ii chemical vapor deposition (CVD. Second, a single CNTs/CF monofilament was selected and encapsulated into a CNTs/CFME with a simple packaging method. The morphologies of as-prepared CNTs/CFs were characterized by scanning electron microscopy. The electrochemical properties of CNTs/CFMEs were measured in potassium ferrocyanide solution (K4Fe(CN6, by using a cyclic voltammetry (CV and a chronoamperometry method. Compared with a bare CFME, a CNTs/CFME showed better CV curves with a higher distinguishable redox peak and response current; the higher the CNT content was, the better the CV curves were. Because the as-grown CNTs significantly enhanced the effective electrode area of CNTs/CFME, the contact area between the electrode and reactant was enlarged, further increasing the electrocatalytic active site density. Furthermore, the modified microelectrode displayed almost the same electrochemical behavior after 104 days, exhibiting remarkable stability and outstanding reproducibility.

Tracing carbon flow from microphytobenthos to major bacterial groups in an intertidal marine sediment by using an in situ

NARCIS (Netherlands)

Miyatake, T.; Moerdijk-Poortvliet, T.C.W.; Stal, L.J.; Boschker, H.T.S.

2014-01-01

Carbon flow from benthic diatoms to heterotrophic bacterial was traced in an intertidal sediment for 5consecutive days. 13C-labeled bicarbonate was sprayed onto the sediment surface during low tide and 13C-labelincorporation in major carbon pools, intermediate metabolites, and biomarkers were

Identification and Selection of Major Carbon Dioxide Stream Compositions

Energy Technology Data Exchange (ETDEWEB)

Last, George V.; Schmick, Mary T.

2011-06-30

A critical component in the assessment of long-term risk from geologic sequestration of CO2 is the ability to predict mineralogical and geochemical changes within storage reservoirs due to rock-brine-CO2 reactions. Impurities and/or other constituents selected for co-sequestration can affect both the chemical and physical (e.g. density, viscosity, interfacial tension) behavior of CO2 in the deep subsurface. These impurities and concentrations are a function of both the industrial source(s) of the CO2, as well as the carbon capture technology used to extract the CO2 and produce a concentrated stream for geologic sequestration. This report summarizes the relative concentrations of CO2 and other constituents in exhaust gases from major non-energy related industrial sources of CO2. Assuming that carbon-capture technology would remove most of the incondensable gases N2, O2, and Ar, leaving SO2 and NOx as the main impurities, we selected four test fluid compositions for use in geochemical experiments. These included: 1) a pure CO2 stream representative of food grade CO2 used in most enhanced oil recovery projects: 2) a test fluid composition containing low concentrations (0.5 mole %) SO2 and NOx (representative of that generated from cement production), 3) a test fluid composition with higher concentrations (2.5 mole %) of SO2, and 4) and test fluid composition containing 3 mole % H2S.

Carbide induced reconstruction of monatomic steps on Ni(111) - A density functional study

DEFF Research Database (Denmark)

Andersson, Martin; Abild-Pedersen, Frank

2007-01-01

We present density functional calculations for carbon adsorption at the two types of monatomic steps on a Ni(111) surface. We show that it is thermodynamically favourable to make a carbon induced clock-type reconstruction at the close-packed step with a [111] step geometry, which creates fourfold...

Carbon dioxide utilization via carbonate-promoted C-H carboxylation.

Science.gov (United States)

Banerjee, Aanindeeta; Dick, Graham R; Yoshino, Tatsuhiko; Kanan, Matthew W

2016-03-10

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO3(2-)) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)--a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO3(2-)-promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres with enhanced photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Qu, Lingling [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Luo, Zhijun, E-mail: lzj@ujs.edu.cn [School of the Environment, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Tang, Chao [Maple Leaf International High School, Zhenjiang 212013 (China)

2013-11-15

Graphical abstract: Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core–shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs). Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation. - Highlights: • One step synthesis of Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon spheres. • Functional groups of sodium gluconate play synergetic roles in the formation of Bi@Bi{sub 2}O{sub 3}@CRCSs. • Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits enhanced photocatalytic activity under visible light irradiation. - Abstract: Bi@Bi{sub 2}O{sub 3}@carboxylate-rich carbon core-shell nanosturctures (Bi@Bi{sub 2}O{sub 3}@CRCSs) have been synthesized via a one-step method. The core–shell nanosturctures of the as-prepared samples were confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Raman spectroscopy. The formation of Bi@Bi{sub 2}O{sub 3}@CRCSs core–shell nanosturctures should attribute to the synergetic roles of different functional groups of sodium gluconate. Bi@Bi{sub 2}O{sub 3}@CRCSs exhibits significant enhanced photocatalytic activity under visible light irradiation (λ > 420 nm) and shows an O{sub 2}-dependent feature. According to trapping experiments of radicals and holes, hydroxyl radicals were not the main active oxidative species in the photocatalytic degradation of MB, but O{sub 2}·{sup −} are the main active oxidative species.

One-step electrochemical composite polymerization of polypyrrole integrated with functionalized graphene/carbon nanotubes nanostructured composite film for electrochemical capacitors

International Nuclear Information System (INIS)

Ding Bing; Lu Xiangjun; Yuan Changzhou; Yang Sudong; Han Yongqin; Zhang Xiaogang; Che Qian

2012-01-01

Graphical abstract: A novel one-step electrochemical co-deposition strategy was first proposed to prepare unique polypyrrole/reduced graphene oxide/carbon nanotubes (PPy/F-RGO/CNTs) ternary composites, where F-RGO, CNTs, and PPy were electrodeposited simultaneously to construct a three-dimensional (3-D) highly porous film electrode. Highlights: ► Isolated, water-soluble graphene was obtained through benzenesulfonic functionalization. ► PPy/F-RGO/CNTs ternary composite film was prepared via one-step electrochemical co-deposition route. ► PPy/F-RGO/CNTs film shows 3-D highly porous nanostructure and high electrical conductivity. ► PPy/F-RGO/CNTs film exhibits high capacitance, good high-rate performance with a remarkable cycling stability. - Abstract: A novel one-step electrochemical composite polymerization strategy was first proposed to prepare unique polypyrrole/reduced graphene oxide/carbon nanotubes (PPy/F-RGO/CNTs) ternary composites, where F-RGO, CNTs, and PPy were electrodeposited simultaneously to construct a three-dimensional (3-D) highly porous film electrode. Such ternary composite film electrode exhibits a high specific capacitance of 300 F g −1 at 1 A g −1 as well as a remarkable cycling stability at high rates, which is related to its unique nanostructure and high electrical conductivity. F-RGO and CNTs act as an electron-transporting backbone of a 3-D porous nanostructure, leaving adequate working space for facile electrolyte penetration and better faradaic utilization of the electro-active PPy. Furthermore, the straightforward approach proposed here can be readily extended to prepare other composite film electrodes with good electrochemical performance for energy storage.

Magneto-carbonization method for production of carbon fiber, and high performance carbon fibers made thereby

Science.gov (United States)

Naskar, Amit K.; Ozcan, Soydan; Eberle, Claude C.; Abdallah, Mohamed Gabr; Mackiewicz, Ludtka Gail; Ludtka, Gerard Michael; Paulauskas, Felix Leonard; Rivard, John Daniel Kennedy

2017-08-08

Method for the preparation of carbon fiber from fiber precursor, wherein the fiber precursor is subjected to a magnetic field of at least 3 Tesla during a carbonization process. The carbonization process is generally conducted at a temperature of at least 400.degree. C. and less than 2200.degree. C., wherein, in particular embodiments, the carbonization process includes a low temperature carbonization step conducted at a temperature of at least or above 400.degree. C. or 500.degree. C. and less than or up to 1000.degree. C., 1100.degree. C., or 1200.degree. C., followed by a high temperature carbonization step conducted at a temperature of at least or above 1200.degree. C. In particular embodiments, particularly in the case of a polyacrylonitrile (PAN) fiber precursor, the resulting carbon fiber may possess a minimum tensile strength of at least 600 ksi, a tensile modulus of at least 30 Msi, and an ultimate elongation of at least 1.5%.

Tritium Removal from Carbon Plasma Facing Components

International Nuclear Information System (INIS)

Skinner, C.H.; Coad, J.P.; Federici, G.

2003-01-01

Tritium removal is a major unsolved development task for next-step devices with carbon plasma-facing components. The 2-3 order of magnitude increase in duty cycle and associated tritium accumulation rate in a next-step tokamak will place unprecedented demands on tritium removal technology. The associated technical risk can be mitigated only if suitable removal techniques are demonstrated on tokamaks before the construction of a next-step device. This article reviews the history of codeposition, the tritium experience of TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) and the tritium removal rate required to support ITER's planned operational schedule. The merits and shortcomings of various tritium removal techniques are discussed with particular emphasis on oxidation and laser surface heating

Tritium Issues in Next Step Devices

Energy Technology Data Exchange (ETDEWEB)

C.H. Skinner; G. Federici

2001-09-05

Tritium issues will play a central role in the performance and operation of next-step deuterium-tritium (DT) burning plasma tokamaks and the safety aspects associated with tritium will attract intense public scrutiny. The orders-of-magnitude increase in duty cycle and stored energy will be a much larger change than the increase in plasma performance necessary to achieve high fusion gain and ignition. Erosion of plasma-facing components will scale up with the pulse length from being barely measurable on existing machines to centimeter scale. Magnetic Fusion Energy (MFE) devices with carbon plasma-facing components will accumulate tritium by co-deposition with the eroded carbon and this will strongly constrain plasma operations. We report on a novel laser-based method to remove co-deposited tritium from carbon plasma-facing components in tokamaks. A major fraction of the tritium trapped in a co-deposited layer during the deuterium-tritium (DT) campaign on the Tokamak Fusion Test Reactor (TFTR) was released by heating with a scanning laser beam. This technique offers the potential for tritium removal in a next-step DT device without the use of oxidation and the associated deconditioning of the plasma-facing surfaces and expense of processing large quantities of tritium oxide. The operational lifetime of alternative materials such as tungsten has significant uncertainties due to melt layer loss during disruptions. Production of dust and flakes will need careful monitoring and minimization, and control and accountancy of the tritium inventory will be critical issues. Many of the tritium issues in Inertial Fusion Energy (IFE) are similar to MFE, but some, for example those associated with the target factory, are unique to IFE. The plasma-edge region in a tokamak has greater complexity than the core due to lack of poloidal symmetry and nonlinear feedback between the plasma and wall. Sparse diagnostic coverage and low dedicated experimental run time has hampered the

Tritium Issues in Next Step Devices

International Nuclear Information System (INIS)

C.H. Skinner; G. Federici

2001-01-01

Tritium issues will play a central role in the performance and operation of next-step deuterium-tritium (DT) burning plasma tokamaks and the safety aspects associated with tritium will attract intense public scrutiny. The orders-of-magnitude increase in duty cycle and stored energy will be a much larger change than the increase in plasma performance necessary to achieve high fusion gain and ignition. Erosion of plasma-facing components will scale up with the pulse length from being barely measurable on existing machines to centimeter scale. Magnetic Fusion Energy (MFE) devices with carbon plasma-facing components will accumulate tritium by co-deposition with the eroded carbon and this will strongly constrain plasma operations. We report on a novel laser-based method to remove co-deposited tritium from carbon plasma-facing components in tokamaks. A major fraction of the tritium trapped in a co-deposited layer during the deuterium-tritium (DT) campaign on the Tokamak Fusion Test Reactor (TFTR) was released by heating with a scanning laser beam. This technique offers the potential for tritium removal in a next-step DT device without the use of oxidation and the associated deconditioning of the plasma-facing surfaces and expense of processing large quantities of tritium oxide. The operational lifetime of alternative materials such as tungsten has significant uncertainties due to melt layer loss during disruptions. Production of dust and flakes will need careful monitoring and minimization, and control and accountancy of the tritium inventory will be critical issues. Many of the tritium issues in Inertial Fusion Energy (IFE) are similar to MFE, but some, for example those associated with the target factory, are unique to IFE. The plasma-edge region in a tokamak has greater complexity than the core due to lack of poloidal symmetry and nonlinear feedback between the plasma and wall. Sparse diagnostic coverage and low dedicated experimental run time has hampered the

One-step oxidation preparation of unfolded and good soluble graphene nanoribbons by longitudinal unzipping of carbon nanotubes

Science.gov (United States)

Hu, Xiaolin; Hu, Yizhen; Huang, Jindan; Zhou, Ning; Liu, Yuhan; Wei, Lin; Chen, Xin; Zhuang, Naifeng

2018-04-01

A simple one-step method to prepare graphene nanoribbon (GNR) is reported in this paper. Compared with water steam etching, the oxidation and co-etching of dilute sulfuric acid can result in the more complete longitudinal unzipping of carbon nanotube, although there is no other strong oxidant. As-prepared GNRs are more flat and have more oxygenated functional groups along the edge. Moreover, they can steadily disperse in a water system. These make them suitable as a carrier for supporting palladium (Pd) nanoparticles. The Pd/GNR composite exhibits a superior electrocatalytic activity for ethanol oxidation.

One-step liquid phase chemical method to prepare carbon-based amorphous molybdenum sulfides: As the effective hydrogen evolution reaction catalysts

International Nuclear Information System (INIS)

Guo, Mengmeng; Wu, Qikang; Yu, Miaomiao; Wang, Yinling; Li, Maoguo

2017-01-01

Two different kinds of carbon-based amorphous molybdenum sulfide composite catalysts (activated carbon supported amorphous molybdenum sulfide and acetylene black supported amorphous molybdenum sulfide) had been prepared in a facile and scalable one-step liquid phase chemical method. The morphological and structural information of catalysts was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and it’s electro-catalytic HER activity were evaluated by linear sweep voltammetry(LSV), amperometric i-t technology and AC impedance technology. The as-prepared carbon-based amorphous molybdenum sulfides showed greatly enhanced electro-catalytic activity for HER compared with pure amorphous molybdenum sulfides. Especially, the nano-sized acetylene black supported molybdenum sulfide exhibited excellent electro-catalytic HER performances with a low onset potential of −116 mV versus reverse hydrogen electrode (RHE) and a small Tafel slope of 51 mV per decade.

Thermodynamic approach and comparison of two-step and single step DME (dimethyl ether) syntheses with carbon dioxide utilization

International Nuclear Information System (INIS)

Chen, Wei-Hsin; Hsu, Chih-Liang; Wang, Xiao-Dong

2016-01-01

DME (Dimethyl ether) synthesis from syngas with CO_2 utilization through two-step and single step processes is analyzed thermodynamically. The influences of reaction temperature, H_2/CO molar ratio, and CO_2/CO molar ratio on CO and CO_2 conversions, DME selectivity and yield, and thermal behavior are evaluated. Particular attention is paid to the comparison of the performance of DME synthesis between the two different methods. In the two-step method, the addition of CO_2 suppresses the CO conversion during methanol synthesis. An increase in CO_2/CO ratio decreases the CO_2 conversion (negative effect), but increases the total consumption amount of CO_2 (positive effect). At a given reaction temperature with H_2/CO = 4, the maximum DME yield develops at CO_2/CO = 1. In the single step method, over 98% of CO can be converted and the DME yield can be as high as 0.52 mol (mol CO)"−"1 at CO_2/CO = 2. The comparison of the single step and two-step processes indicates that the maximum CO conversion, DME selectivity, and DME yield in the former are higher than those in the latter, whereas an opposite result in the maximum CO_2 conversion is observed. These results reveal that the single step process has lower thermodynamic limitation and is a better option for DME synthesis. From CO_2 utilization point of view, the operation with low temperature, high H_2/CO ratio, and low CO_2/CO ratio results in higher CO_2 conversion, irrespective of two-step or single step DME synthesis. - Highlights: • DME (Dimethyl ether) synthesis with CO_2 utilization is analyzed thermodynamically. • Single step and two-step DME syntheses are studied and compared with each other. • CO_2 addition suppresses CO conversion in MeOH synthesis but increases MeOH yield. • The performance of the single step DME synthesis is better than that of the two-step one. • Increase CO_2/CO ratio decreases CO_2 conversion but increases CO_2 consumption amount.

One-step synthesis of multi-emission carbon nanodots for ratiometric temperature sensing

Science.gov (United States)

Nguyen, Vanthan; Yan, Lihe; Xu, Huanhuan; Yue, Mengmeng

2018-01-01

Measuring temperature with greater precision at localized small length scales or in a nonperturbative manner is a necessity in widespread applications, such as integrated photonic devices, micro/nano electronics, biology, and medical diagnostics. To this context, use of nanoscale fluorescent temperature probes is regarded as the most promising method for temperature sensing because they are noninvasive, accurate, and enable remote micro/nanoscale imaging. Here, we propose a novel ratiometric fluorescent sensor for nanothermometry using carbon nanodots (C-dots). The C-dots were synthesized by one-step method using femtosecond laser ablation and exhibit unique multi-emission property due to emissions from abundant functional groups on its surface. The as-prepared C-dots demonstrate excellent ratiometric temperature sensing under single wavelength excitation that achieves high temperature sensitivity with a 1.48% change per °C ratiometric response over wide-ranging temperature (5-85 °C) in aqueous buffer. The ratiometric sensor shows excellent reversibility and stability, holding great promise for the accurate measurement of temperature in many practical applications.

Synthesis of carbon nanoparticles using one step green approach and their application as mercuric ion sensor

Energy Technology Data Exchange (ETDEWEB)

Roshni, V.; Ottoor, Divya, E-mail: divya@chem.unipune.ac.in

2015-05-15

Carbon nanoparticles (CNPs) have been evolved as a promising candidate for the metal sensing applications due to their synthesis from naturally occurring and easily available non-toxic molecular precursors by green chemistry. A simple and one step procedure is reported here for the synthesis of CNPs from coconut milk by thermal pyrolysis at a temperature of 120–150 °C for 2–5 min without using any carbonizing or passivating agent. On pyrolysis the coconut oil is separated from the carbon rich residue and the residue when dissolved in water showed blue fluorescence under UV light. The CNPs produced are found to show an emission maximum at 440 nm when excited at 360 nm. Synthesis by green approach makes CNPs a promising substitute for the metal sensing applications. Series of metal ions which have a hazardous impact on the ecological system have been taken for the analysis and it is observed that the fluorescence of CNPs gets remarkably quenched by mercuric ions. Fluorescence quenching was studied using standard Stern–Volmer quenching model. Limit of detection was found to be 16.5 nM Hg{sup 2+} concentration. - Highlights: • Green and economical synthesis of carbon nanoparticles (CNPs) from naturally abundant material. • Coconut milk is used as molecular precursor, which on thermal pyrolysis at 120 °C yielded CNPs. • Highly fluorescent CNPs show an emission maxima of 440 nm when excited at 360 nm. • Application of CNPs for metal ion sensing using fluorescence quenching phenomena. • Hg{sup 2+} is most effectively sensed with a detection limit of 16.5 nM.

Synthesis of carbon nanoparticles using one step green approach and their application as mercuric ion sensor

International Nuclear Information System (INIS)

Roshni, V.; Ottoor, Divya

2015-01-01

Carbon nanoparticles (CNPs) have been evolved as a promising candidate for the metal sensing applications due to their synthesis from naturally occurring and easily available non-toxic molecular precursors by green chemistry. A simple and one step procedure is reported here for the synthesis of CNPs from coconut milk by thermal pyrolysis at a temperature of 120–150 °C for 2–5 min without using any carbonizing or passivating agent. On pyrolysis the coconut oil is separated from the carbon rich residue and the residue when dissolved in water showed blue fluorescence under UV light. The CNPs produced are found to show an emission maximum at 440 nm when excited at 360 nm. Synthesis by green approach makes CNPs a promising substitute for the metal sensing applications. Series of metal ions which have a hazardous impact on the ecological system have been taken for the analysis and it is observed that the fluorescence of CNPs gets remarkably quenched by mercuric ions. Fluorescence quenching was studied using standard Stern–Volmer quenching model. Limit of detection was found to be 16.5 nM Hg 2+ concentration. - Highlights: • Green and economical synthesis of carbon nanoparticles (CNPs) from naturally abundant material. • Coconut milk is used as molecular precursor, which on thermal pyrolysis at 120 °C yielded CNPs. • Highly fluorescent CNPs show an emission maxima of 440 nm when excited at 360 nm. • Application of CNPs for metal ion sensing using fluorescence quenching phenomena. • Hg 2+ is most effectively sensed with a detection limit of 16.5 nM

Step sites in syngas catalysis

DEFF Research Database (Denmark)

Rostrup-Nielsen, J.; Nørskov, Jens Kehlet

2006-01-01

Step sites play an important role in many catalytic reactions. This paper reviews recent results on metal catalysts for syngas reactions with emphasis on steam reforming. Modern characterization techniques (STEM, HREM...) and theoretical calculations (DFT) has allowed a more quantitative explanat......Step sites play an important role in many catalytic reactions. This paper reviews recent results on metal catalysts for syngas reactions with emphasis on steam reforming. Modern characterization techniques (STEM, HREM...) and theoretical calculations (DFT) has allowed a more quantitative...... explanation of the impact of step sites on catalyst activity and side reactions such as carbon formation. This leads to a discussion of principles for catalyst promotion....

A review on soil carbon accumulation due to the management change of major Brazilian agricultural activities

Directory of Open Access Journals (Sweden)

N. La Scala Júnior

Full Text Available Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha-1 year-1. The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha-1 year-1. The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.

A review on soil carbon accumulation due to the management change of major Brazilian agricultural activities.

Science.gov (United States)

La Scala, N; De Figueiredo, E B; Panosso, A R

2012-08-01

Agricultural areas deal with enormous CO2 intake fluxes offering an opportunity for greenhouse effect mitigation. In this work we studied the potential of soil carbon sequestration due to the management conversion in major agricultural activities in Brazil. Data from several studies indicate that in soybean/maize, and related rotation systems, a significant soil carbon sequestration was observed over the year of conversion from conventional to no-till practices, with a mean rate of 0.41 Mg C ha(-1) year(-1). The same effect was observed in sugarcane fields, but with a much higher accumulation of carbon in soil stocks, when sugarcane fields are converted from burned to mechanised based harvest, where large amounts of sugarcane residues remain on the soil surface (1.8 Mg C ha(-1) year(-1)). The higher sequestration potential of sugarcane crops, when compared to the others, has a direct relation to the primary production of this crop. Nevertheless, much of this mitigation potential of soil carbon accumulation in sugarcane fields is lost once areas are reformed, or intensive tillage is applied. Pasture lands have shown soil carbon depletion once natural areas are converted to livestock use, while integration of those areas with agriculture use has shown an improvement in soil carbon stocks. Those works have shown that the main crop systems of Brazil have a huge mitigation potential, especially in soil carbon form, being an opportunity for future mitigation strategies.

Effect of one step KOH activation and CaO modified carbon in transesterification reaction

Science.gov (United States)

Yacob, Abd Rahim; Zaki, Muhammad Azam Muhammad

2017-11-01

In this work, one step activation was introduced using potassium hydroxide (KOH) and calcium oxide (CaO) modified palm kernel shells. Various concentration of calcium oxide was used as catalyst while maintaining the same concentration of potassium hydroxide to activate and impregnate the palm kernel shell before calcined at 500°C for 5 hours. All the prepared samples were characterized using Fourier Transform Infrared (FTIR) and Field Emission Scanning Electron Microscope (FESEM). FTIR analysis of raw palm kernel shell showed the presence of various functional groups. However, after activation, most of the functional groups were eliminated. The basic strength of the prepared samples were determined using back titration method. The samples were then used as base heterogeneous catalyst for the transesterification reaction of rice bran oil with methanol. Analysis of the products were performed using Gas Chromatography Flame Ionization Detector (GC-FID) to calculate the percentage conversion of the biodiesel products. This study shows, as the percentage of one step activation potassium and calcium oxide doped carbon increases thus, the basic strength also increases followed by the increase in biodiesel production. Optimization study shows that the optimum biodiesel production was at 8 wt% catalyst loading, 9:1 methanol: oil molar ratio at 65°C and 6 hours which gives a conversion up to 95%.

Carbon Capture and Storage: Progress and Next Steps

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

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

Chemical recycling of carbon dioxide emissions from a cement plant into dimethyl ether, a case study of an integrated process in France using a Reverse Water Gas Shift (RWGS) step

International Nuclear Information System (INIS)

Vibhatavata, Phuangphet; Borgard, Jean-Marc; Tabarant, Michel; Bianchi, Daniel; Mansilla, Christine

2013-01-01

Recycling of carbon dioxide (CO 2 ) and hydrogen (H 2 ) into liquid fuel technology has recently gained wide public interest since it is a potential pathway to increase the liquid fuel supply and to mitigate CO 2 emissions simultaneously. In France, the majority of the electricity production is derived from nuclear and renewable energy which have a low CO 2 footprint. This electricity power enables a potential for massive hydrogen production with low carbon emissions. We studied the possibility to develop this technology at an industrial scale in the French context on a typical industrial example of a cement manufacture in the south of France. An integrated process is proposed, which enables the use of the heat released by the CO 2 to fuel process to help to capture the CO 2 released by the cement manufacture. Some technological issues are discussed, and a potential solution is proposed for the catalyst used in the critical step of the Reverse Water Gas-Shift reaction (RWGS) of the process. (authors)

Carbon outcomes of major land-cover transitions in SE Asia

DEFF Research Database (Denmark)

Ziegler, Alan D.; Phelps, Jacob; Yuen, Jia Qi

2012-01-01

Policy makers across the tropics propose that carbon finance could provide incentives for forest frontier communities to transition away from swidden agriculture (slash-and-burn or shifting cultivation) to other systems that potentially reduce emissions and/or increase carbon sequestration. However......-use regimes optimize or increase carbon sequestration. As some transitions may negatively impact other ecosystem services, food security, and local livelihoods, the entire carbon and noncarbon benefit stream should also be taken into account before prescribing transitions with ambiguous carbon benefits...

Major role of marine vegetation on the oceanic carbon cycle

Directory of Open Access Journals (Sweden)

C. M. Duarte

2005-01-01

Full Text Available The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove forests to the global level and a top-down approach derived from considerations of global sediment balance and a compilation of the organic carbon content of vegeatated sediments. Up-scaling of individual burial estimates values yielded a total carbon burial in vegetated habitats of 111 Tmol C y-1. The total burial in unvegetated sediments was estimated to be 126 Tg C y-1, resulting in a bottom-up estimate of total burial in the ocean of about 244 Tg C y-1, two-fold higher than estimates of oceanic carbon burial that presently enter global carbon budgets. The organic carbon concentrations in vegetated marine sediments exceeds by 2 to 10-fold those in shelf/deltaic sediments. Top-down recalculation of ocean sediment budgets to account for these, previously neglected, organic-rich sediments, yields a top-down carbon burial estimate of 216 Tg C y-1, with vegetated coastal habitats contributing about 50%. Even though vegetated carbon burial contributes about half of the total carbon burial in the ocean, burial represents a small fraction of the net production of these ecosystems, estimated at about 3388 Tg C y-1, suggesting that bulk of the benthic net ecosystem production must support excess respiration in other compartments, such as unvegetated sediments and the coastal pelagic compartment. The total excess organic carbon available to be exported to the ocean is estimated at between 1126 to 3534 Tg C y-1, the bulk of which must be respired in the open ocean. Widespread loss of vegetated coastal habitats must have reduced carbon burial in the ocean by about 30 Tg C y-1, identifying the destruction of these ecosystems as an important loss of CO

One-step synthesis of SnCo nanoconfined in hierarchical carbon nanostructures for lithium ion battery anode.

Science.gov (United States)

Qin, Jian; Liu, Dongye; Zhang, Xiang; Zhao, Naiqin; Shi, Chunsheng; Liu, En-Zuo; He, Fang; Ma, Liying; Li, Qunying; Li, Jiajun; He, Chunnian

2017-10-26

A new strategy for the one-step synthesis of a 0D SnCo nanoparticles-1D carbon nanotubes-3D hollow carbon submicrocube cluster (denoted as SnCo@CNT-3DC) hierarchical nanostructured material was developed via a simple chemical vapor deposition (CVD) process with the assistance of a water-soluble salt (NaCl). The adopted NaCl not only acted as a cubic template for inducing the formation of the 3D hollow carbon submicrocube cluster but also provides a substrate for the SnCo catalysts impregnation and CNT growth, ultimately leading to the successful construction of the unique 0D-1D-3D structured SnCo@CNT-3DC during the CVD of C 2 H 2 . When utilized as a lithium-ion battery anode, the SnCo@CNT-3DC composite electrode demonstrated an excellent rate performance and cycling stability for Li-ion storage. Specifically, an impressive reversible capacity of 826 mA h g -1 after 100 cycles at 0.1 A g -1 and a high rate capacity of 278 mA h g -1 even after 1000 cycles at 5 A g -1 were achieved. This remarkable electrochemical performance could be ascribed to the unique hierarchical nanostructure of SnCo@CNT-3DC, which guarantees a deep permeation of electrolytes and a shortened lithium salt diffusion pathway in the solid phase as well as numerous hyperchannels for electron transfer.

Reducing carbon dioxide to products

Science.gov (United States)

Cole, Emily Barton; Sivasankar, Narayanappa; Parajuli, Rishi; Keets, Kate A

2014-09-30

A method reducing carbon dioxide to one or more products may include steps (A) to (C). Step (A) may bubble said carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode may reduce said carbon dioxide into said products. Step (B) may adjust one or more of (a) a cathode material, (b) a surface morphology of said cathode, (c) said electrolyte, (d) a manner in which said carbon dioxide is bubbled, (e), a pH level of said solution, and (f) an electrical potential of said divided electrochemical cell, to vary at least one of (i) which of said products is produced and (ii) a faradaic yield of said products. Step (C) may separate said products from said solution.

Semiconductor-Based Photoelectrochemical Conversion of Carbon Dioxide: Stepping Towards Artificial Photosynthesis.

Science.gov (United States)

Pang, Hong; Masuda, Takuya; Ye, Jinhua

2018-01-18

The photoelectrochemical (PEC) carbon dioxide reduction process stands out as a promising avenue for the conversion of solar energy into chemical feedstocks, among various methods available for carbon dioxide mitigation. Semiconductors derived from cheap and abundant elements are interesting candidates for catalysis. Whether employed as intrinsic semiconductors or hybridized with metallic cocatalysts, biocatalysts, and metal molecular complexes, semiconductor photocathodes exhibit good performance and low overpotential during carbon dioxide reduction. Apart from focusing on carbon dioxide reduction materials and chemistry, PEC cells towards standalone devices that use photohybrid electrodes or solar cells have also been a hot topic in recent research. An overview of the state-of-the-art progress in PEC carbon dioxide reduction is presented and a deep understanding of the catalysts of carbon dioxide reduction is also given. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

One-step synthesis of nitrogen-doped carbon nanodots for ratiometric pH sensing by femtosecond laser ablation method

International Nuclear Information System (INIS)

Xu, Huanhuan; Yan, Lihe; Nguyen, Vanthan; Yu, Yang; Xu, Yanmin

2017-01-01

Highlights: • Nitrogen-containing carbon nanodots (CDs) are synthesize using pulsed laser ablation in liquid. • The CDs show a strong fluorescence consisting of a dual-band luminescence peak. • The as prepared CDs can offer a ratiometric sensing platform for the detection the pH values. - Abstract: Nitrogen-doped carbon nanodots (CDs) are synthesized by one-step femtosecond laser ablation of graphite powder in aminotoluene at room temperature. The as-prepared CDs have the average diameter of 2.87 nm and possess an excitation-independent emission covering nearly the whole visible light region at a single excitation wavelength. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis indicate that there are a huge number of multiple oxygen groups and amine groups on the surface of the CDs. As their different fluorescence peaks originated from different emission surface groups on the nanodots show different pH dependence, these CDs can be used for ratiometric pH sensing.

One-step synthesis of nitrogen-doped carbon nanodots for ratiometric pH sensing by femtosecond laser ablation method

Energy Technology Data Exchange (ETDEWEB)

Xu, Huanhuan [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab. of Information Photonic Technique, School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Lihe, E-mail: liheyan@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab. of Information Photonic Technique, School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Nguyen, Vanthan [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab. of Information Photonic Technique, School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Le Quy Don Technical University, Hanoi 122314 (Viet Nam); Yu, Yang; Xu, Yanmin [Key Laboratory for Physical Electronics and Devices of the Ministry of Education and Shaanxi Key Lab. of Information Photonic Technique, School of Electronics and Information Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

2017-08-31

Highlights: • Nitrogen-containing carbon nanodots (CDs) are synthesize using pulsed laser ablation in liquid. • The CDs show a strong fluorescence consisting of a dual-band luminescence peak. • The as prepared CDs can offer a ratiometric sensing platform for the detection the pH values. - Abstract: Nitrogen-doped carbon nanodots (CDs) are synthesized by one-step femtosecond laser ablation of graphite powder in aminotoluene at room temperature. The as-prepared CDs have the average diameter of 2.87 nm and possess an excitation-independent emission covering nearly the whole visible light region at a single excitation wavelength. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis indicate that there are a huge number of multiple oxygen groups and amine groups on the surface of the CDs. As their different fluorescence peaks originated from different emission surface groups on the nanodots show different pH dependence, these CDs can be used for ratiometric pH sensing.

Strategic Planning Information Online: A Step-by-Step Guide through Major Checkpoints. . . What Database to Use When.

Science.gov (United States)

Marsh, Sharon G.

1984-01-01

This article concentrates on the use of online searching to provide information needed by business for strategy formulation. The following steps are explained: environment analysis (structural analysis, trend analysis); business analysis; strategy formulation; strategic anticipation; strategic plan formalization; and implementation and control.…

Allochthonous Carbon--a Major Driver of Bacterioplankton Production in the Subarctic Northern Baltic Sea.

Science.gov (United States)

Figueroa, D; Rowe, O F; Paczkowska, J; Legrand, C; Andersson, A

2016-05-01

Heterotrophic bacteria are, in many aquatic systems, reliant on autochthonous organic carbon as their energy source. One exception is low-productive humic lakes, where allochthonous dissolved organic matter (ADOM) is the major driver. We hypothesized that bacterial production (BP) is similarly regulated in subarctic estuaries that receive large amounts of riverine material. BP and potential explanatory factors were measured during May-August 2011 in the subarctic Råne Estuary, northern Sweden. The highest BP was observed in spring, concomitant with the spring river-flush and the lowest rates occurred during summer when primary production (PP) peaked. PLS correlations showed that ∼60% of the BP variation was explained by different ADOM components, measured as humic substances, dissolved organic carbon (DOC) and coloured dissolved organic matter (CDOM). On average, BP was threefold higher than PP. The bioavailability of allochthonous dissolved organic carbon (ADOC) exhibited large spatial and temporal variation; however, the average value was low, ∼2%. Bioassay analysis showed that BP in the near-shore area was potentially carbon limited early in the season, while BP at seaward stations was more commonly limited by nitrogen-phosphorus. Nevertheless, the bioassay indicated that ADOC could contribute significantly to the in situ BP, ∼60%. We conclude that ADOM is a regulator of BP in the studied estuary. Thus, projected climate-induced increases in river discharge suggest that BP will increase in subarctic coastal areas during the coming century.

Promotion of the oxidation of carbon monoxide at stepped platinum single-crystal electrodes in alkaline media by lithium and beryllium cations.

Science.gov (United States)

Stoffelsma, Chantal; Rodriguez, Paramaconi; Garcia, Gonzalo; Garcia-Araez, Nuria; Strmcnik, Dusan; Marković, Nenad M; Koper, Marc T M

2010-11-17

The role of alkali cations (Li(+), Na(+), K(+), Cs(+), and Be(2+)) on the blank voltammetric response and the oxidative stripping of carbon monoxide from stepped Pt single-crystal electrodes in alkaline media has been investigated by cyclic voltammetry. A strong influence of the nature of the cation on both the blank voltammetric profile and the CO oxidation is observed and related to the influence of the cation on the specific adsorption of OH on the platinum surface. Especially Li(+) and Be(2+) cations markedly affect the adsorption of OH and thereby have a significant promoting effect on CO(ads) oxidation. The voltammetric experiments suggest that, on Pt(111), the influence of Li(+) (and Be(2+)) is primarily through a weakening of the repulsive interactions between the OH in the OH adlayer, whereas in the presence of steps also, the onset of OH adsorption is at a lower potential, both on steps and on terraces.

Major role of marine vegetation on the oceanic carbon cycle

NARCIS (Netherlands)

Duarte, C.M.; Middelburg, J.J.; Caraco, N.

2005-01-01

The carbon burial in vegetated sediments, ignored in past assessments of carbon burial in the ocean, was evaluated using a bottom-up approach derived from upscaling a compilation of published individual estimates of carbon burial in vegetated habitats (seagrass meadows, salt marshes and mangrove

Application of probabilistic event attribution in the summer heat extremes in the western US to emissions traced to major industrial carbon producers

Science.gov (United States)

Mera, R. J.; Allen, M. R.; Mote, P.; Ekwurzel, B.; Frumhoff, P. C.; Rupp, D. E.

2015-12-01

Heat waves in the western US have become progressively more severe due to increasing relative humidity and nighttime temperatures, increasing the health risks of vulnerable portions of the population, including Latino farmworkers in California's Central Valley and other socioeconomically disadvantaged communities. Recent research has shown greenhouse gas emissions doubled the risk of the hottest summer days during the 2000's in the Central Valley, increasing public health risks and costs, and raising the question of which parties are responsible for paying these costs. It has been argued that these costs should not be taken up solely by the general public through taxation, but that additional parties can be considered, including multinational corporations who have extracted and marketed a large proportion of carbon-based fuels. Here, we apply probabilistic event attribution (PEA) to assess the contribution of emissions traced to the world's 90 largest major industrial carbon producers to the severity and frequency of these extreme heat events. Our research uses very large ensembles of regional climate model simulations to calculate fractional attribution of policy-relevant extreme heat variables. We compare a full forcings world with observed greenhouse gases, sea surface temperatures and sea ice extent to a counter-factual world devoid of carbon pollution from major industrial carbon producers. The results show a discernable fraction of record-setting summer temperatures in the western US during the 2000's can be attributed to emissions sourced from major carbon producers.

Microwave-assisted one-step synthesis of white light-emitting carbon dot suspensions

Science.gov (United States)

Vanessa, Hinterberger; Wenshuo, Wang; Cornelia, Damm; Simon, Wawra; Martin, Thoma; Wolfgang, Peukert

2018-06-01

In this contribution, we demonstrate that an aqueous solution with adjustable fluorescent color, including white light emission, can be achieved by a rapid one-step microwave synthesis method resulting in a mixture of blue-emitting carbon dots (CDs) and the yellow-emitting 2,3-diaminophenazine (DAP). Aqueous mixtures of o-phenylene-diamine (oPD) and citric acid (CA) are used as precursors. The resulting product structures are analyzed by FT-IR and NMR spectroscopy and the size of the resulting CDs is determined by atomic force microscopy to be 1.1 ± 0.3 nm. The synthesized solution exhibits two fluorescence emission peaks at 430 and 560 nm, which were found to originate from the CDs and DAP, respectively. The intensity ratio of both fluorescence peaks depends on pH, which is driven by the protonation state of DAP. In consequence, the fluorescence emission color of the CD solution can be tuned precisely and reproducibly from blue to white to yellow by careful control of the pH. Finally, at a pH level of 5.4, at which there is equal blue and yellow emission intensity, a white light emitting solution can be successfully produced in a very fast and simple synthesis procedure.

Majorization arrow in quantum-algorithm design

International Nuclear Information System (INIS)

Latorre, J.I.; Martin-Delgado, M.A.

2002-01-01

We apply majorization theory to study the quantum algorithms known so far and find that there is a majorization principle underlying the way they operate. Grover's algorithm is a neat instance of this principle where majorization works step by step until the optimal target state is found. Extensions of this situation are also found in algorithms based in quantum adiabatic evolution and the family of quantum phase-estimation algorithms, including Shor's algorithm. We state that in quantum algorithms the time arrow is a majorization arrow

Scanning Tunneling Microscopy Evidence for the Dissociation of Carbon Monoxide on Ruthenium Steps

DEFF Research Database (Denmark)

Tison, Yann; Nielsen, Kenneth; Mowbray, Duncan J.

2012-01-01

–Tropsch processes under certain conditions, has been debated for years. Here, scanning tunneling microscopy (STM) and density functional theory (DFT) are used to clarify the role of monatomic steps in the splitting of CO on a stepped Ru(0 1 54) crystal, which displays alternating steps with either 4-fold or 3-fold...... symmetry. After CO doses at elevated temperatures, the STM images reveal step decorations characteristic of atomic oxygen resulting from CO dissociation on every second step. The comparison of the STM images with the results of DFT calculations shows that the step decoration occurs on the steps displaying...

Tracing carbon flow from microphytobenthos to major bacterial groups in an intertidal marine sediment by using an in situ 13C pulse-chase method

NARCIS (Netherlands)

Miyatake, T.; Moerdijk-Poortvliet, T.C.W.; Stal, L.J.; Boschker, H.T.S.

2014-01-01

Carbon flow from benthic diatoms to heterotrophic bacterial was traced in an intertidal sediment for 5 consecutive days. 13C-labeled bicarbonate was sprayed onto the sediment surface during low tide and 13C-label incorporation in major carbon pools, intermediate metabolites, and biomarkers were

Carbonation of metal silicates for long-term CO2 sequestration

Science.gov (United States)

Blencoe, James G; Palmer, Donald A; Anovitz, Lawrence M; Beard, James S

2014-03-18

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Carboxysomal carbonic anhydrases: Structure and role in microbial CO2 fixation

Energy Technology Data Exchange (ETDEWEB)

Cannon, Gordon C.; Heinhorst, Sabine; Kerfeld, Cheryl A.

2010-06-23

Cyanobacteria and some chemoautotrophic bacteria are able to grow in environments with limiting CO2 concentrations by employing a CO2-concentrating mechanism (CCM) that allows them to accumulate inorganic carbon in their cytoplasm to concentrations several orders of magnitude higher than that on the outside. The final step of this process takes place in polyhedral protein microcompartments known as carboxysomes, which contain the majority of the CO2-fixing enzyme, RubisCO. The efficiency of CO2 fixation by the sequestered RubisCO is enhanced by co-localization with a specialized carbonic anhydrase that catalyzes dehydration of the cytoplasmic bicarbonate and ensures saturation of RubisCO with its substrate, CO2. There are two genetically distinct carboxysome types that differ in their protein composition and in the carbonic anhydrase(s) they employ. Here we review the existing information concerning the genomics, structure and enzymology of these uniquely adapted carbonic anhydrases, which are of fundamental importance in the global carbon cycle.

One-step synthesis of continuous free-standing Carbon Nanotubes-Titanium oxide composite films as anodes for lithium-ion batteries

International Nuclear Information System (INIS)

Gao, Hongxu; Hou, Feng; Wan, Zhipeng; Zhao, Sha; Yang, Deming; Liu, Jiachen; Guo, Anran; Gong, Yuxuan

2015-01-01

Highlights: • CNTs/TiO 2 compoiste films synthesized are continuous and free-standing. • The film can be directly used as flexible, binder-free Lithium-Ion Battery electrode. • The CNTs/TiO 2 electrodes exhibit excellent rate capacity and cyclic stability. • Our strategy is readily applicable to fabricate other CNTs-based composite films. - Abstract: Continuous free-standing Carbon Nanotubes (CNTs)/Titanium oxide (TiO 2 ) composite films were fabricated in a vertical CVD gas flow reactor with water sealing by the One-Step Chemical Vapor Deposition (CVD) approach. The composite films consist of multiple layers of conductive carbon nanotube networks with titanium oxide nanoparticles decorating on carbon nanotube surface. The as-synthesized flexible and transferrable composite films show excellent electrochemical properties, when the content of tetrabutyl titanate is 19.0 wt.%, which can be promising as binder-free anodes for Lithium-Ion Battery (LIB) applications. It demonstrates remarkably high rate capacity of 150 mAh g −1 , as well as excellent high rate cyclic stability over 500 cycles (current density of 3000 mA g −1 ). Such observations can be attributed to the relatively larger surface area and pore volume comparing with pristine CNT films. Great potentials of CNTs/TiO 2 composite films for large-scale production and application in energy devices were shown

Minimizing Freshwater Consumption in the Wash-Off Step in Textile Reactive Dyeing by Catalytic Ozonation with Carbon Aerogel Hosted Bimetallic Catalyst

Directory of Open Access Journals (Sweden)

Enling Hu

2018-02-01

Full Text Available In textile reactive dyeing, dyed fabrics have to be rinsed in the wash-off step several times to improve colorfastness. Thus, the multiple rinsing processes drastically increase the freshwater consumption and meanwhile generate massive waste rinsing effluents. This paper addresses an innovative alternative to recycle the waste effluents to minimize freshwater consumption in the wash-off step. Accordingly, catalytic ozonation with a highly effective catalyst has been applied to remedy the waste rinsing effluents for recycling. The carbon aerogel (CA hosted bimetallic hybrid material (Ag–Fe2O3@CA was fabricated and used as the catalyst in the degradation of residual dyes in the waste rinsing effluents by ozonation treatments. The results indicate the participation of Ag–Fe2O3@CA had strikingly enhanced the removal percentage of chemical oxidation demand by 30%. In addition, it has been validated that waste effluents had been successfully reclaimed after catalytic ozonation with Ag–Fe2O3@CA. They could be additionally reused to reduce freshwater consumption in the wash-off step, but without sacrificing the color quality of corresponding fabrics in terms of color difference and colorfastness. This study may be the first to report the feasibility of catalytic ozonation in minimization of freshwater consumption in the wash-off step in textile reactive dyeing.

Focused-electron-beam-induced processing (FEBIP) for emerging applications in carbon nanoelectronics

International Nuclear Information System (INIS)

Fedorov, Andrei G.; Kim, Songkil; Henry, Mathias; Kulkarni, Dhaval; Tsukruk, Vladimir V.

2014-01-01

Focused-electron-beam-induced processing (FEBIP), a resist-free additive nanomanufacturing technique, is an actively researched method for ''direct-write'' processing of a wide range of structural and functional nanomaterials, with high degree of spatial and time-domain control. This article attempts to critically assess the FEBIP capabilities and unique value proposition in the context of processing of electronics materials, with a particular emphasis on emerging carbon (i.e., based on graphene and carbon nanotubes) devices and interconnect structures. One of the major hurdles in advancing the carbon-based electronic materials and device fabrication is a disjoint nature of various processing steps involved in making a functional device from the precursor graphene/CNT materials. Not only this multi-step sequence severely limits the throughput and increases the cost, but also dramatically reduces the processing reproducibility and negatively impacts the quality because of possible between-the-step contamination, especially for impurity-susceptible materials such as graphene. The FEBIP provides a unique opportunity to address many challenges of carbon nanoelectronics, especially when it is employed as part of an integrated processing environment based on multiple ''beams'' of energetic particles, including electrons, photons, and molecules. This avenue is promising from the applications' prospective, as such a multi-functional (electron/photon/molecule beam) enables one to define shapes (patterning), form structures (deposition/etching), and modify (cleaning/doping/annealing) properties with locally resolved control on nanoscale using the same tool without ever changing the processing environment. It thus will have a direct positive impact on enhancing functionality, improving quality and reducing fabrication costs for electronic devices, based on both conventional CMOS and emerging carbon (CNT/graphene) materials. (orig.)

Formation of oxygen related donors in step-annealed CZ–silicon

Indian Academy of Sciences (India)

The effect of step-annealing necessitated by the difficulties being faced in the long duration annealing treatments to be given to CZ–silicon has been studied. One pre-anneal of 10 h followed by annealing of 10 h causes a decrease in the absorption coefficient for carbon (c). Oxygen and carbon both accelerate thermal ...

Microwave pyrolysis using self-generated pyrolysis gas as activating agent: An innovative single-step approach to convert waste palm shell into activated carbon

Science.gov (United States)

Yek, Peter Nai Yuh; Keey Liew, Rock; Shahril Osman, Mohammad; Chung Wong, Chee; Lam, Su Shiung

2017-11-01

Waste palm shell (WPS) is a biomass residue largely available from palm oil industries. An innovative microwave pyrolysis method was developed to produce biochar from WPS while the pyrolysis gas generated as another product is simultaneously used as activating agent to transform the biochar into waste palm shell activated carbon (WPSAC), thus allowing carbonization and activation to be performed simultaneously in a single-step approach. The pyrolysis method was investigated over a range of process temperature and feedstock amount with emphasis on the yield and composition of the WPSAC obtained. The WPSAC was tested as dye adsorbent in removing methylene blue. This pyrolysis approach provided a fast heating rate (37.5°/min) and short process time (20 min) in transforming WPS into WPSAC, recording a product yield of 40 wt%. The WPSAC was detected with high BET surface area (≥ 1200 m2/g), low ash content (< 5 wt%), and high pore volume (≥ 0.54 cm3/g), thus recording high adsorption efficiency of 440 mg of dye/g. The desirable process features (fast heating rate, short process time) and the recovery of WPSAC suggest the exceptional promise of the single-step microwave pyrolysis approach to produce high-grade WPSAC from WPS.

Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal.

Science.gov (United States)

Altmann, Johannes; Rehfeld, Daniel; Träder, Kai; Sperlich, Alexander; Jekel, Martin

2016-04-01

Adsorption onto granular activated carbon (GAC) is an established technology in water and advanced wastewater treatment for the removal of organic substances from the liquid phase. Besides adsorption, the removal of particulate matter by filtration and biodegradation of organic substances in GAC contactors has frequently been reported. The application of GAC as both adsorbent for organic micropollutant (OMP) removal and filter medium for solids retention in tertiary wastewater filtration represents an energy- and space saving option, but has rarely been considered because high dissolved organic carbon (DOC) and suspended solids concentrations in the influent of the GAC adsorber put a significant burden on this integrated treatment step and might result in frequent backwashing and unsatisfactory filtration efficiency. This pilot-scale study investigates the combination of GAC adsorption and deep-bed filtration with coagulation as a single advanced treatment step for simultaneous removal of OMPs and phosphorus from secondary effluent. GAC was assessed as upper filter layer in dual-media downflow filtration and as mono-media upflow filter with regard to filtration performance and OMP removal. Both filtration concepts effectively removed suspended solids and phosphorus, achieving effluent concentrations of 0.1 mg/L TP and 1 mg/L TSS, respectively. Analysis of grain size distribution and head loss within the filter bed showed that considerable head loss occurred in the topmost filter layer in downflow filtration, indicating that most particles do not penetrate deeply into the filter bed. Upflow filtration exhibited substantially lower head loss and effective utilization of the whole filter bed. Well-adsorbing OMPs (e.g. benzotriazole, carbamazepine) were removed by >80% up to throughputs of 8000-10,000 bed volumes (BV), whereas weakly to medium adsorbing OMPs (e.g. primidone, sulfamethoxazole) showed removals activated carbon (PAC) to deep-bed filtration as a direct

Optimization of process parameters during carbonization for improved carbon fibre strength

Science.gov (United States)

Köhler, T.; Pursche, F.; Burscheidt, P.; Seide, G.; Gries, T.

2017-10-01

Based on their extraordinary properties, carbon fibres nowadays play a significant role in modern industries. In the last years carbon fibres are increasingly used for lightweight constructions in the energy or the transportation industry. However, a bigger market penetration of carbon fibres is still hindered by high prices (~ 22 /kg) [3]. One crucial step in carbon fibre production is the process of carbonization of stabilized fibres. However, the cause effect relationships of carbonization are nowadays not fully understood. Therefore, the main goal of this research work is the quantification of the cause-effect relationships of process parameters like temperature and residence time on carbon fibre strength.

Carbonation of metal silicates for long-term CO.sub.2 sequestration

Energy Technology Data Exchange (ETDEWEB)

Blencoe, James G.; Palmer, Donald A.; Anovitz, Lawrence M.; Beard, James S.

2017-08-01

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Carbonation of metal silicates for long-term CO.sub.2 sequestration

Science.gov (United States)

Blencoe, James G [Harriman, TN; Palmer, Donald A [Oliver Springs, TN; Anovitz, Lawrence M [Knoxville, TN; Beard, James S [Martinsville, VA

2012-02-14

In a preferred embodiment, the invention relates to a process of sequestering carbon dioxide. The process comprises the steps of: (a) reacting a metal silicate with a caustic alkali-metal hydroxide to produce a hydroxide of the metal formerly contained in the silicate; (b) reacting carbon dioxide with at least one of a caustic alkali-metal hydroxide and an alkali-metal silicate to produce at least one of an alkali-metal carbonate and an alkali-metal bicarbonate; and (c) reacting the metal hydroxide product of step (a) with at least one of the alkali-metal carbonate and the alkali-metal bicarbonate produced in step (b) to produce a carbonate of the metal formerly contained in the metal silicate of step (a).

Carbon Micronymphaea: Graphene on Vertically Aligned Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Jong Won Choi

2013-01-01

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

Activated carbon fibers and engineered forms from renewable resources

Science.gov (United States)

Baker, Frederick S

2013-02-19

A method of producing activated carbon fibers (ACFs) includes the steps of providing a natural carbonaceous precursor fiber material, blending the carbonaceous precursor material with a chemical activation agent to form chemical agent-impregnated precursor fibers, spinning the chemical agent-impregnated precursor material into fibers, and thermally treating the chemical agent-impregnated precursor fibers. The carbonaceous precursor material is both carbonized and activated to form ACFs in a single step. The method produces ACFs exclusive of a step to isolate an intermediate carbon fiber.

Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk

International Nuclear Information System (INIS)

Katsuki, Hiroaki; Komarneni, Sridhar

2009-01-01

Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO 2 and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 deg. C for 2-6 h by changing the SiO 2 /Al 2 O 3 , H 2 O/Na 2 O and Na 2 O/SiO 2 molar ratios of precursors in the two-step process. The surface area and NH 4 + -cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m 2 /g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m 2 /g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of ∼3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously. - Graphical Abstract: Novel Na-X zeolite/porous carbon composite.

Steps toward Gaining Knowledge of World Music Pedagogy

Science.gov (United States)

Carlisle, Katie

2013-01-01

This article presents steps toward gaining knowledge of world music pedagogy for K-12 general music educators. The majority of the article details steps that invite engagement within everyday contexts with accessible resources within local and online communities. The steps demonstrate ways general music teachers can diversify and self-direct their…

One-step formation of lipid-polyacrylic acid-calcium carbonate nanoparticles for co-delivery of doxorubicin and curcumin.

Science.gov (United States)

Peng, Jianqing; Fumoto, Shintaro; Miyamoto, Hirotaka; Chen, Yi; Kuroda, Naotaka; Nishida, Koyo

2017-09-01

A doxorubicin (Dox) and curcumin (Cur) combination treatment regimen has been widely studied in pre-clinical research. However, the nanoparticles developed for this combination therapy require a consecutive drug loading process because of the different water-solubility of these drugs. This study provides a strategy for the "one-step" formation of nanoparticles encapsulating both Dox and Cur. We took advantage of polyacrylic acid (PAA) and calcium carbonate (CaCO 3 ) to realise a high drug entrapment efficiency (EE) and pH-sensitive drug release using a simplified preparation method. Optimisation of lipid ratios and concentrations of CaCO 3 was conducted. Under optimal conditions, the mean diameter of PEGylated lipid/PAA/CaCO 3 nanoparticles with encapsulated Cur and Dox (LPCCD) was less than 100 nm. An obvious pH-sensitive release of both drugs was observed, with different Dox and Cur release rates. Successful co-delivery of Cur and Dox was achieved via LPCCD on HepG2 cells. LPCCD altered the bio-distribution of Dox and Cur in vivo and decreased Dox-induced cardiotoxicity. The current investigation has developed an efficient ternary system for co-delivery of Dox and Cur to tumours, using a "one-step" formation resulting in nanoparticles possessing remarkable pH-sensitive drug release behaviour, which may be valuable for further clinical studies and eventual clinical application.

Microstructural evolution and mechanical properties of low-carbon steel treated by a two-step quenching and partitioning process

Energy Technology Data Exchange (ETDEWEB)

Yan, Shu [The State Key Laboratory of Rolling & Automation, Northeastern University, Shenyang 110819 (China); Liu, Xianghua, E-mail: liuxh@mail.neu.edu.cn [The State Key Laboratory of Rolling & Automation, Northeastern University, Shenyang 110819 (China); Research Academy, Northeastern University, Shenyang 110819 (China); Liu, Wayne J [Research Academy, Northeastern University, Shenyang 110819 (China); Lan, Huifang; Wu, Hongyan [The State Key Laboratory of Rolling & Automation, Northeastern University, Shenyang 110819 (China)

2015-07-29

The quenching and partitioning (Q&P) process is studied in Ti-bearing low-carbon steel. Detailed characterization of the microstructural evolution is performed by means of optical microscopy, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results indicate that the investigated steel subjected to the Q&P process forms a multiphase microstructure of primarily lath martensite, with small amounts of plate-type martensite and retained austenite. The distribution and morphology of the retained austenite are observed; moreover the relationship between the phase fraction of the retained austenite, its carbon concentration, and the partitioning conditions is established. Carbides preferentially precipitate within the plate-type martensite at first, and gradually form in the martensitic laths over time during the partitioning step. Additionally, titanium precipitations contribute to both the refinement of prior austenite grains and the improvement of strength by precipitation strengthening. The results of mechanical properties testing indicate that the samples partitioned at 400 °C exhibit a superior combination of strength and elongation, with products of the two properties ranging between 19.6 and 20.9 GPa%. Based on analysis of work hardening behavior it is determined that the higher ductility is closely related to the higher phase fraction and/or stability of retained austenite.

Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

Energy Technology Data Exchange (ETDEWEB)

Jin, Yongzhong [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Chen, Jian, E-mail: wuhangzs@163.com [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Fu, Qingshan [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China); Li, Binghong [China Rubber Group Carbon Black Industry Research and Design Institute, 643000 Zigong, Sichuan (China); Zhang, Huazhi; Gong, Yong [Department of Materials and Chemistry Engineering, Sichuan University of Science and Engineering, 643000 Zigong, Sichuan (China)

2015-01-01

Graphical abstract: - Highlights: • HCNFs were synthesized by one-step CVD using cupric tartrate as a catalyst at temperature below 500 °C. • The synthesis of HCNFs is highly temperature-dependent at the synthesis temperature of 280–480 °C. • The addition of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system. - Abstract: Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry–differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C{sub 4}H{sub 4}CuO{sub 6} → Cu reaction occurs at ∼250–310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100–400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5–1 μm and fiber diameter of 100–200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system.

Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

International Nuclear Information System (INIS)

Jin, Yongzhong; Chen, Jian; Fu, Qingshan; Li, Binghong; Zhang, Huazhi; Gong, Yong

2015-01-01

Graphical abstract: - Highlights: • HCNFs were synthesized by one-step CVD using cupric tartrate as a catalyst at temperature below 500 °C. • The synthesis of HCNFs is highly temperature-dependent at the synthesis temperature of 280–480 °C. • The addition of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system. - Abstract: Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry–differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C 4 H 4 CuO 6 → Cu reaction occurs at ∼250–310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100–400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5–1 μm and fiber diameter of 100–200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system

Stochastic Lot-Sizing under Carbon Emission Control for Profit Optimisation in MTO Manufacturing

Directory of Open Access Journals (Sweden)

Qiao A.

2017-01-01

Full Text Available Aggravating global warming has heightened the imminent need by the world to step up forceful efforts on curbing emission of greenhouse gases. Although manufacturing is a major resource of carbon emission, few research works have studied the impacts of carbon constraints on manufacturing, leading to environmentally unsustainable production strategies and operations. This paper incorporates carbon emission management into production planning for make-to-order (MTO manufacturing. This paper proposes a model that solves lot-sizing problems to maximise profits under carbon emission caps. The model adopts stochastic interarrival times for customer orders to enhance the practicality of the results for real-world manufacturing. Numerical experiments show that reducing carbon emission undercuts short-term profits of a company. However, it is conducive to the company’s market image as being socially responsible which would attract more customers who concern about environmental protection. Hence, reducing carbon emission in manufacturing is beneficial to long-term profitability and sustainability. The results provide managerial insights into manufacture operations for balancing profitability and carbon control.

[Collaborative application of BEPS at different time steps.

Science.gov (United States)

Lu, Wei; Fan, Wen Yi; Tian, Tian

2016-09-01

BEPSHourly is committed to simulate the ecological and physiological process of vegetation at hourly time steps, and is often applied to analyze the diurnal change of gross primary productivity (GPP), net primary productivity (NPP) at site scale because of its more complex model structure and time-consuming solving process. However, daily photosynthetic rate calculation in BEPSDaily model is simpler and less time-consuming, not involving many iterative processes. It is suitable for simulating the regional primary productivity and analyzing the spatial distribution of regional carbon sources and sinks. According to the characteristics and applicability of BEPSDaily and BEPSHourly models, this paper proposed a method of collaborative application of BEPS at daily and hourly time steps. Firstly, BEPSHourly was used to optimize the main photosynthetic parameters: the maximum rate of carboxylation (V c max ) and the maximum rate of photosynthetic electron transport (J max ) at site scale, and then the two optimized parameters were introduced into BEPSDaily model to estimate regional NPP at regional scale. The results showed that optimization of the main photosynthesis parameters based on the flux data could improve the simulate ability of the model. The primary productivity of different forest types in descending order was deciduous broad-leaved forest, mixed forest, coniferous forest in 2011. The collaborative application of carbon cycle models at different steps proposed in this study could effectively optimize the main photosynthesis parameters V c max and J max , simulate the monthly averaged diurnal GPP, NPP, calculate the regional NPP, and analyze the spatial distribution of regional carbon sources and sinks.

Multiyear high-resolution carbon exchange over European croplands from the integration of observed crop yields into CarbonTracker Europe

Science.gov (United States)

Combe, Marie; Vilà-Guerau de Arellano, Jordi; de Wit, Allard; Peters, Wouter

2016-04-01

Carbon exchange over croplands plays an important role in the European carbon cycle over daily-to-seasonal time scales. Not only do crops occupy one fourth of the European land area, but their photosynthesis and respiration are large and affect CO2 mole fractions at nearly every atmospheric CO2 monitoring site. A better description of this crop carbon exchange in our CarbonTracker Europe data assimilation system - which currently treats crops as unmanaged grasslands - could strongly improve its ability to constrain terrestrial carbon fluxes. Available long-term observations of crop yield, harvest, and cultivated area allow such improvements, when combined with the new crop-modeling framework we present. This framework can model the carbon fluxes of 10 major European crops at high spatial and temporal resolution, on a 12x12 km grid and 3-hourly time-step. The development of this framework is threefold: firstly, we optimize crop growth using the process-based WOrld FOod STudies (WOFOST) agricultural crop growth model. Simulated yields are downscaled to match regional crop yield observations from the Statistical Office of the European Union (EUROSTAT) by estimating a yearly regional parameter for each crop species: the yield gap factor. This step allows us to better represent crop phenology, to reproduce the observed multiannual European crop yields, and to construct realistic time series of the crop carbon fluxes (gross primary production, GPP, and autotrophic respiration, Raut) on a fine spatial and temporal resolution. Secondly, we combine these GPP and Raut fluxes with a simple soil respiration model to obtain the total ecosystem respiration (TER) and net ecosystem exchange (NEE). And thirdly, we represent the horizontal transport of carbon that follows crop harvest and its back-respiration into the atmosphere during harvest consumption. We distribute this carbon using observations of the density of human and ruminant populations from EUROSTAT. We assess the model

The construction of geological model using an iterative approach (Step 1 and Step 2)

International Nuclear Information System (INIS)

Matsuoka, Toshiyuki; Kumazaki, Naoki; Saegusa, Hiromitsu; Sasaki, Keiichi; Endo, Yoshinobu; Amano, Kenji

2005-03-01

One of the main goals of the Mizunami Underground Research Laboratory (MIU) Project is to establish appropriate methodologies for reliably investigating and assessing the deep subsurface. This report documents the results of geological modeling of Step 1 and Step 2 using the iterative investigation approach at the site-scale (several 100m to several km in area). For the Step 1 model, existing information (e.g. literature), and results from geological mapping and reflection seismic survey were used. For the Step 2 model, additional information obtained from the geological investigation using existing borehole and the shallow borehole investigation were incorporated. As a result of this study, geological elements that should be represented in the model were defined, and several major faults with trends of NNW, EW and NE trend were identified (or inferred) in the vicinity of the MIU-site. (author)

A one-step single source route to carbon nanotubes

Indian Academy of Sciences (India)

Carbon nanotubes (CNTs) have been synthesized via directly pyrolyzing ferrocene in the autoclave. The nanotubes with several micrometers in length have outer and inner diameters in the range of 40–100 nm and 20–40 nm, respectively. An yield of ∼70% of CNTs can be obtained without any accessorial solvents and ...

Use of seeds to control precipitation of calcium carbonate and determination of seed nature.

Science.gov (United States)

Donnet, Marcel; Bowen, Paul; Jongen, Nathalie; Lemaître, Jacques; Hofmann, Heinrich

2005-01-04

Understanding and controlling precipitation reactions is a major challenge for industrial crystallization. Calcium carbonate is a widely studied system: more than 3000 papers have been devoted to the subject over the past 10 years. The first step of the precipitation of calcium carbonate, from relatively concentrated solutions (0.01 mol/L), involves the formation of an initial gel phase which later transforms into calcite, vaterite, or a mixture of both phases. Our work aimed at controlling this first step. Nanosized seeds (8 nm), formed in situ, were used in order to control the often chaotic nucleation step which normally leads to poor phase selection and broad particle size distributions. Seeding has often been used to avoid spontaneous nucleation in metastable solutions for growth mechanism investigations of single-crystal calcium carbonate. Here the ability of a seeding method to control the precipitation reaction evolution even in the case of high supersaturation is demonstrated. The seeds and the presence of a polymeric additive (poly(acrylic acid)) allow the control of the precipitated polymorph and the specific surface area, while maintaining a narrow particle size distribution in the submicron range. Direct characterization methods did not succeed in identifying these nanoseeds; indirect methods using solubility calculations are used to demonstrate their existence and quantify size and number density of the nanosized seeds.

Mangroves, a major source of dissolved organic carbon to the oceans

Science.gov (United States)

Dittmar, Thorsten; Hertkorn, Norbert; Kattner, Gerhard; Lara, RubéN. J.

2006-03-01

Organic matter, which is dissolved in low concentrations in the vast waters of the oceans, contains a total amount of carbon similar to atmospheric carbon dioxide. To understand global biogeochemical cycles, it is crucial to quantify the sources of marine dissolved organic carbon (DOC). We investigated the impact of mangroves, the dominant intertidal vegetation of the tropics, on marine DOC inventories. Stable carbon isotopes and proton nuclear magnetic resonance spectroscopy showed that mangroves are the main source of terrigenous DOC in the open ocean off northern Brazil. Sunlight efficiently destroyed aromatic molecules during transport offshore, removing about one third of mangrove-derived DOC. The remainder was refractory and may thus be distributed over the oceans. On a global scale, we estimate that mangroves account for >10% of the terrestrially derived, refractory DOC transported to the ocean, while they cover only <0.1% of the continents' surface.

Removal of uranium(VI) from aqueous solutions by new phosphorus-containing carbon spheres synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid

International Nuclear Information System (INIS)

Zhi-bin Zhang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan; Zhi-wei Zhou; Xiao-hong Cao; Yun-hai Liu; Guo-xuan Xiong; East China Institute of Technology, Fuzhou; Ping Liang; East China Institute of Technology, Fuzhou; China University of Geosciences, Wuhan

2014-01-01

The novel phosphorus-rich hydrothermal carbon spheres (HCSs-PO 4 ) have been synthesized via one-step hydrothermal carbonization of glucose in the presence of phosphoric acid. The textural and surface chemistry properties were characterized using Boehm titrations, scanning electron microscopy and Fourier transform infrared spectrometer. The content of oxygen-containing functional groups on the surface of HCSs increased from 0.053 to 1.009 mmol g -1 by phosphate group modification. The adsorption ability of HCSsPO 4 has been explored for the removal of uranium from aqueous solutions. The adsorption kinetic data were best described by the pseudo-second-order equation. Adsorption process could be well defined by the Langmuir isotherm, the adsorption capacity of HCSs increased from 80.00 to 285.70 mg g -1 after phosphate group modification. And thermodynamic parameters indicated the adsorption process was feasible,endothermic and spontaneous. Selective adsorption studies showed that the HCSs-PO 4 could selectively remove U(VI), and the selectivity coefficients had been improved in the presence of co-existing ions, Na(I), Ni(II), Sr(II), Mn(II), Mg(II) and Zn(II). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 12.0 g HCSs-PO 4 . (author)

Improving the actinides recycling in closed fuel cycles, a major step towards nuclear energy sustainability

International Nuclear Information System (INIS)

Poinssot, C.; Grandjean, S.; Masson, M.; Bouillis, B.; Warin, D.

2013-01-01

Increasing the sustainability of nuclear energy is a longstanding road that requires a stepwise approach to successively tackle the following 3 objectives. First of all, optimize the consumption of natural resource to preserve them for future generations and hence guarantee the energetic independence of the countries (no uranium ore is needed anymore). The current twice-through cycle of Pu implemented by France, UK, Japan and soon China is a first step in this direction and already allows the development and optimization of the relevant industrial processes. It also allows a major improvement regarding the conditioning of the ultimate waste in a durable and robust nuclear glass. Secondly, the recycling of americium could be an interesting option for the future with the deployment of FR fleet to save the repository resource and optimize its use by allowing a denser disposal. It would limit the burden towards the future generations and the need for additional repositories before several centuries. Thirdly, the recycling of the whole minor actinides inventory could be an interesting option for the far-future for strongly decreasing the waste long-term toxicity, down to a few centuries. It would bring the waste issue back within the human history, which should promote its acceptance by the social opinion

Analyses of one-step liquid hydrogen production from methane and landfill gas

Energy Technology Data Exchange (ETDEWEB)

Huang, Cunping; T-Raissi, Ali [University of Central Florida, Florida Solar Energy Center, 1679 Clearlake Road, Cocoa, FL 32922-5703 (United States)

2007-11-15

Conventional liquid hydrogen (LH{sub 2}) production consists of two basic steps: (1) gaseous hydrogen (GH{sub 2}) production via steam methane reformation followed by purification by means of pressure swing adsorption (PSA), and (2) GH{sub 2} liquefaction. LH{sub 2} produced by the conventional processes is not carbon neutral because of the carbon dioxide (CO{sub 2}) emission from PSA operation. A novel concept is herein presented and flowsheeted for LH{sub 2} production with zero carbon emission using methane (CH{sub 4}) or landfill gas as feedstock. A cryogenic process is used for both H{sub 2} separation/purification and liquefaction. This one-step process can substantially increase the efficiency and reduce costs because no PSA step is required. Furthermore, the integrated process results in no CO{sub 2} emissions and minimal H{sub 2} losses. Of the five flowsheets presented, one that combines low and high temperature CO/CH{sub 4} reforming reactions in a single reactor shows the highest overall efficiency with the first and second law efficiencies of 85% and 56%, respectively. The latter figure assumes 10% overall energy loss and 30% efficiency for the cryogenic process. (author)

Value of a step-up diagnosis plan: CRP and CT-scan to diagnose and manage postoperative complications after major abdominal surgery

Directory of Open Access Journals (Sweden)

Jennifer Straatman

2014-12-01

Full Text Available Postoperative complications frequently follow major abdominal surgery and are associated with increased morbidity and mortality. Early diagnosis and treatment of complications is associated with improved patient outcome. In this study we assessed the value of a step-up diagnosis plan by C-reactive protein and CT-scan (computed tomography-scan imaging for detection of postoperative complications following major abdominal surgery. An observational cohort study was conducted of 399 consecutive patients undergoing major abdominal surgery between January 2009 and January 2011. Indication for operation, type of surgery, postoperative morbidity, complications according to the Clavien-Dindo classification and mortality were recorded. Clinical parameters were recorded until 14 days postoperatively or until discharge. Regular C-reactive protein (CPR measurements in peripheral blood and on indication -enhanced CT-scans were performed. Eighty-three out of 399 (20.6 % patients developed a major complication in the postoperative course after a median of seven days (IQR 4-9 days. One hundred and thirty two patients received additional examination consisting of enhanced CT-scan imaging, and treatment by surgical reintervention or intensive care observation. CRP levels were significantly higher in patients with postoperative complications. On the second postoperative day CRP levels were on average 197.4 mg/L in the uncomplicated group, 220.9 mg/L in patients with a minor complication and 280.1 mg/L in patients with major complications (p < 0,001. CT-scan imaging showed a sensitivity of 91.7 % and specificity of 100 % in diagnosis of major complications. Based on clinical deterioration and the increase of CRP, an additional enhanced CT-scan offered clear discrimination between patients with major abdominal complications and uncomplicated patients. Adequate treatment could then be accomplished.

One-Step Self-Assembly Synthesis α-Fe2O3 with Carbon-Coated Nanoparticles for Stabilized and Enhanced Supercapacitors Electrode

Directory of Open Access Journals (Sweden)

Yizhi Yan

2017-08-01

Full Text Available A cocoon-like α-Fe2O3 nanocomposite with a novel carbon-coated structure was synthesized via a simple one-step hydrothermal self-assembly method and employed as supercapacitor electrode material. It was observed from electrochemical measurements that the obtained α-Fe2O3@C electrode showed a good specific capacitance (406.9 Fg−1 at 0.5 Ag−1 and excellent cycling stability, with 90.7% specific capacitance retained after 2000 cycles at high current density of 10 Ag−1. These impressive results, presented here, demonstrated that α-Fe2O3@C could be a promising alternative material for application in high energy density storage.

Variation in carbon stocks on different slope aspects in seven major ...

Indian Academy of Sciences (India)

forest types of temperate region of Garhwal Himalaya, India ... density, tree density, biomass and soil organic carbon (SOC) on four aspects, ..... soil by metal cylinder of 30 cm length and 3 cm internal .... high inflammability of igniting material due to a low water .... carbon emission to the atmosphere by forest management.

Densities of carbon foils

International Nuclear Information System (INIS)

Stoner, J.O. Jr.

1991-01-01

The densities of arc-evaporated carbon target foils have been measured by several methods. The density depends upon the method used to measure it; for the same surface density, values obtained by different measurement techniques may differ by fifty percent or more. The most reliable density measurements are by flotation, yielding a density of 2.01±0.03 g cm -3 , and interferometric step height with the surface density known from auxiliary measurements, yielding a density of 2.61±0.4 g cm -3 . The difference between these density values mayy be due in part to the compressive stresses that carbon films have while still on their substrates, uncertainties in the optical calibration of surface densities of carbon foils, and systematic errors in step-height measurements. Mechanical thickness measurements by micrometer caliper are unreliable due to nonplanarity of these foils. (orig.)

Two-step sulfonation process for the conversion of polymer fibers to carbon fibers

Science.gov (United States)

Barton, Bryan E.; Patton, Jasson T.; Hukkanen, Eric J.; Bernius, Mark T.

2017-11-14

Disclosed herein are processes for preparing carbon fibers, comprising: sulfonating a polymer fiber with a sulfonating agent that is fuming sulfuric acid, sulfuric acid, chlorosulfonic acid, or a combination thereof; treating the sulfonated polymer with a heated solvent, wherein the temperature of the heated solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 501-3000.degree. C. Carbon fibers prepared according to these methods are also disclosed herein.

Arbuscular mycorrhizal fungi increase organic carbon decomposition under elevated carbon dioxide

Science.gov (United States)

A major goal of climate change research is to understand whether and how terrestrial ecosystems can sequester more carbon to mitigate rising atmospheric carbon dioxide (CO2) levels. The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric CO2 has been assumed to be a major mecha...

Plasma-material interactions in current tokamaks and their implications for next step fusion reactors

International Nuclear Information System (INIS)

Federici, G.; Skinner, C.H.; Brooks, J.N.

2001-01-01

The major increase in discharge duration and plasma energy in a next step DT fusion reactor will give rise to important plasma-material effects that will critically in influence its operation, safety and performance. Erosion will increase to a scale of several centimetres from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma facing components. Controlling plasma-wall interactions is critical to achieving high performance in present day tokamaks, and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena stimulated an internationally co-ordinated effort in the part of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor project (ITER), and significant progress has been made in better understanding these issues. The paper reviews the underlying physical processes and the existing experimental database of plasma-material inter actions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next step fusion reactors. Two main topical groups of interaction are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation and (ii) tritium retention and removal. The use of modelling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D avenues for their resolution are presented. (author)

Plasma-material interactions in current tokamaks and their implications for next-step fusion reactors

International Nuclear Information System (INIS)

Federici, G.; Skinner, C.H.; Brooks, J.N.

2001-01-01

The major increase in discharge duration and plasma energy in a next-step DT fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety and performance. Erosion will increase to a scale of several cm from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma-facing components. Controlling plasma wall interactions is critical to achieving high performance in present-day tokamaks and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena has stimulated an internationally co-ordinated effort in the field of plasma-surface interactions supporting the engineering design activities of the international thermonuclear experimental reactor project (ITER) and significant progress has been made in better understanding these issues. This paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next-step fusion reactors. Two main topical groups of interactions are considered: (i) erosion/re-deposition from plasma sputtering and disruptions, including dust and flake generation, (ii) tritium retention and removal. The use of modelling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D avenues for their resolution are presented. (orig.)

Cyclic process for producing methane from carbon monoxide with heat removal

Science.gov (United States)

Frost, Albert C.; Yang, Chang-lee

1982-01-01

Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

Tracing carbon flow from microphytobenthos to major bacterial groups in an intertidal marine sediment by using an in situ 13C pulse-chase method

OpenAIRE

Miyatake, T.; Moerdijk-Poortvliet, T.C.W.; Stal, L.J.; Boschker, H.T.S.

2014-01-01

Carbon flow from benthic diatoms to heterotrophic bacterial was traced in an intertidal sediment for 5 consecutive days. 13C-labeled bicarbonate was sprayed onto the sediment surface during low tide and 13C-label incorporation in major carbon pools, intermediate metabolites, and biomarkers were monitored. Phospholipid-derived fatty acid (PLFA) and ribosomal ribonucleic acid (rRNA) were used to identify the responsible members of the microbial community at class and family phylogenetic resolut...

Study of lithium insertion in hard carbon made from cotton wool

Science.gov (United States)

Peled, Emanuel; Eshkenazi, Victor; Rosenberg, Yuri

Hard-carbon materials were made either by one-step or multi-step pyrolysis of cotton cloth between 700 and 1100°C. All carbons have been characterized by gas sorption, X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) techniques. Two types of carbons have been obtained. One, made by multi-step pyrolysis, has the highest lithium reversible capacity [about 600 (mA h)/g] and two distinct voltage regions: a sloping one between 1.5 and about 0.1 V, called the high-voltage region (HVR), and a horizontal one between 0.1 and 0 V, called the low-voltage plateau (LVP). The other carbons made by the one-step process have only the HVR and less capacity [up to 470 (mA h)/g]. The influence of the current density and temperature on the capacity and degradation rate in both LVP and HVR was checked. We suggest that there are two different modes of lithium insertion: intercalation-like (on both sides of single graphene sheets) at lower potentials and chemical binding to edge carbon atoms at higher potentials vs. lithium reference electrode. A schematic model for lithiated carbon is proposed.

Stepwise hydrogeological modeling and groundwater flow analysis on site scale (Step 0 and Step 1)

International Nuclear Information System (INIS)

Ohyama, Takuya; Saegusa, Hiromitsu; Onoe, Hironori

2005-05-01

One of the main goals of the Mizunami Underground Research Laboratory Project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. To achieve this goal, a variety of investigations, analysis, and evaluations have been conducted using an iterative approach. In this study, hydrogeological modeling and ground water flow analyses have been carried out using the data from surface-based investigations at Step 0 and Step 1, in order to synthesize the investigation results, to evaluate the uncertainty of the hydrogeological model, and to specify items for further investigation. The results of this study are summarized as follows: 1) As the investigation progresses Step 0 to Step 1, the understanding of groundwater flow was enhanced from Step 0 to Step 1, and the hydrogeological model could be revised, 2) The importance of faults as major groundwater flow pathways was demonstrated, 3) Geological and hydrogeological characteristics of faults with orientation of NNW and NE were shown to be especially significant. The main item specified for further investigations is summarized as follows: geological and hydrogeological characteristics of NNW and NE trending faults are important. (author)

Carbon Footprint Calculator | Climate Change | US EPA

Science.gov (United States)

2016-12-12

An interactive calculator to estimate your household's carbon footprint. This tool will estimate carbon pollution emissions from your daily activities and show how to reduce your emissions and save money through simple steps.

Surface treated carbon catalysts produced from waste tires for fatty acids to biofuel conversion

Science.gov (United States)

Hood, Zachary D.; Adhikari, Shiba P.; Wright, Marcus W.; Lachgar, Abdessadek; Li, Yunchao; Naskar, Amit K.; Paranthaman, Mariappan Parans

2018-02-06

A method of making solid acid catalysts includes the step of sulfonating waste tire pieces in a first sulfonation step. The sulfonated waste tire pieces are pyrolyzed to produce carbon composite pieces having a pore size less than 10 nm. The carbon composite pieces are then ground to produce carbon composite powders having a size less than 50 .mu.m. The carbon composite particles are sulfonated in a second sulfonation step to produce sulfonated solid acid catalysts. A method of making biofuels and solid acid catalysts are also disclosed.

Nanoscale Electrochemistry of sp(2) Carbon Materials: From Graphite and Graphene to Carbon Nanotubes.

Science.gov (United States)

Unwin, Patrick R; Güell, Aleix G; Zhang, Guohui

2016-09-20

Carbon materials have a long history of use as electrodes in electrochemistry, from (bio)electroanalysis to applications in energy technologies, such as batteries and fuel cells. With the advent of new forms of nanocarbon, particularly, carbon nanotubes and graphene, carbon electrode materials have taken on even greater significance for electrochemical studies, both in their own right and as components and supports in an array of functional composites. With the increasing prominence of carbon nanomaterials in electrochemistry comes a need to critically evaluate the experimental framework from which a microscopic understanding of electrochemical processes is best developed. This Account advocates the use of emerging electrochemical imaging techniques and confined electrochemical cell formats that have considerable potential to reveal major new perspectives on the intrinsic electrochemical activity of carbon materials, with unprecedented detail and spatial resolution. These techniques allow particular features on a surface to be targeted and models of structure-activity to be developed and tested on a wide range of length scales and time scales. When high resolution electrochemical imaging data are combined with information from other microscopy and spectroscopy techniques applied to the same area of an electrode surface, in a correlative-electrochemical microscopy approach, highly resolved and unambiguous pictures of electrode activity are revealed that provide new views of the electrochemical properties of carbon materials. With a focus on major sp(2) carbon materials, graphite, graphene, and single walled carbon nanotubes (SWNTs), this Account summarizes recent advances that have changed understanding of interfacial electrochemistry at carbon electrodes including: (i) Unequivocal evidence for the high activity of the basal surface of highly oriented pyrolytic graphite (HOPG), which is at least as active as noble metal electrodes (e.g., platinum) for outer

One-step fabrication of heterogeneous conducting polymers-coated graphene oxide/carbon nanotubes composite films for high-performance supercapacitors

International Nuclear Information System (INIS)

Zhou, Haihan; Han, Gaoyi

2016-01-01

Highlights: • CPs-GO/CNTs ternary composites have been prepared via one-step electrodeposition. • The composites show a GO supported CPs-coated CNTs ternary hybrid microstructure. • The capacitive nature of CPs-GO is promoted significantly by introducing CNTs. • CPs-GO/CNTs electrodes show high areal capacitance and excellent cycle stability. - Abstract: Composite films of heterogeneous conducting polymers-coated graphene oxide/carbon nanotubes (CPs-GO/CNTs; CPs, PPy and PEDOT) have been fabricated via one-step electrochemical co-deposition. Scanning electron microscope and transmission electron microscopy characterizations indicate that the as-prepared CPs-GO/CNTs composites show a GO supported CPs-coated CNTs ternary hybrid microstructure. The electrochemical measurements including cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy tests manifest that the capacitive performances of CPs-GO electrodes are obviously promoted as the introduction of CNTs, and the PEDOT-GO/CNTs electrodes exhibit the more significantly improved electrochemical performances as the more CNTs introduced. Furthermore, the as-prepared PPy-GO/CNTs and PEDOT-GO/CNTs ternary composites achieve a high areal specific capacitance (142.2 mF cm −2 and 99.0 mF cm −2 at 1.0 mA cm −2 , respectively), together with superior rate capability, and excellent cycle stability (maintain 97.3% and 99.2% of initial capacitance for 5000 cycles, respectively), which are essential for their applications in high-performance supercapacitor electrodes.

Organic carbon source and salinity shape sediment bacterial composition in two China marginal seas and their major tributaries.

Science.gov (United States)

Wang, Kai; Zou, Li; Lu, Xinxin; Mou, Xiaozhen

2018-08-15

Marginal sea sediments receive organic substrates of different origins, but whether and to what extent sediment microbial communities are reflective of the different sources of organic substrates remain unclear. To address these questions, sediment samples were collected in two connected China marginal seas, i.e., Bohai Sea and Yellow Sea, and their two major tributaries (Yellow River and Liao River). Sediment bacterial community composition (BCC) was examined using 16S rRNA gene pyrosequencing. In addition, physicochemical variables that describe environmental conditions and sediment features were measured. Our results revealed that BCCs changed with salinity and organic carbon (OC) content. Members of Gaiellaceae and Comamonadaceae showed a rapid decrease as salinity and phytoplankton-derived OC increased, while Piscirickettsiaceae and Desulfobulbaceae exhibited an opposite distribution pattern. Differences of riverine vs. marginal sea sediment BCCs could be mostly explained by salinity. However, within the marginal seas, sediment BCC variations were mainly explained by OC-related variables, including terrestrial-derived fatty acids (Terr_FA), phytoplankton-derived polyunsaturated fatty acids (Phyto_PUFA), stable carbon isotopes (δ 13 C), and carbon to nitrogen ratio (C/N). In addition to environmental variables, network analysis suggested that interactions among individual bacterial taxa might be important in shaping sediment BCCs in the studied areas. Copyright © 2018 Elsevier B.V. All rights reserved.

Carbon activation process for increased surface accessibility in electrochemical capacitors

Science.gov (United States)

Doughty, Daniel H.; Eisenmann, Erhard T.

2001-01-01

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

Structure in nascent carbon nanotubes revealed by spatially resolved Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Landois, Périne [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Pinault, Mathieu [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Huard, Mickaël [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Reita, Valérie [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Rouzière, Stéphan; Launois, Pascale [Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris Sud 11, 91405 Orsay (France); Mayne-L' Hermite, Martine [CEA, IRAMIS, SPAM, Laboratoire Francis Perrin (CNRS URA 2453), 91191 Gif-sur-Yvette (France); Bendiab, Nedjma, E-mail: nedjma.bendiab@grenoble.cnrs.fr [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France)

2014-10-01

The understanding of carbon nanotube (CNT) growth is crucial for the control of their production. In particular, the identification of structural changes of carbon possibly occurring near the catalyst particle in the very early stages of their formation is of high interest. In this study, samples of nascent CNT obtained during nucleation step and samples of vertically aligned CNT obtained during growth step are analysed by combined spatially resolved Raman spectroscopy and X-ray diffraction measurements. Spatially resolved Raman spectroscopy reveals that iron-based phases and carbon phases are co-localized at the same position, and indicates that sp{sup 2} carbon nucleates preferentially on iron-based particles during this nucleation step. Depth scan Raman spectroscopy analysis, performed on nascent CNT, highlights that carbon structural organisation is significantly changing from defective graphene layers surrounding the iron-based particles at their base up to multi-walled nanotube structures in the upper part of iron-based particles. - Highlights: • Spatial co-localization of iron and carbon structures in nascent carbon nanotubes • Imaging local carbon structure changes along catalyst particles by Raman spectroscopy. • In nascent nanotubes, significant structural changes occur along catalyst particle.

Low-temperature synthesis and characterization of helical carbon fibers by one-step chemical vapour deposition

Science.gov (United States)

Jin, Yongzhong; Chen, Jian; Fu, Qingshan; Li, Binghong; Zhang, Huazhi; Gong, Yong

2015-01-01

Helical carbon fibers (HCNFs) were synthesized by one-step chemical vapour deposition using cupric tartrate as a catalyst at temperature below 500 °C. The bound rubber of natural rubber (NR)/HCNFs were also prepared in this study. The results of thermogravimetry-differential scanning calorimetry (TG/DSC) for cupric tartrate nanoparticles show that the transformation of C4H4CuO6 → Cu reaction occurs at ∼250-310 °C. The characterization of scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and Raman spectrum for the synthesized products confirms that the synthesis of HCNFs is highly temperature-dependent. The straight fibers with the fiber diameter of 100-400 nm are obtained at 280 °C and HCNFs can be synthesized at higher temperature, with the coil diameter of 0.5-1 μm and fiber diameter of 100-200 nm at 380 °C, and the coil diameter of ∼100 nm and fiber diameter of ∼80 nm at 480 °C. The maximum of the bound-rubber content (37%) can be obtained with the addition of 100 wt.% HCNFs in NR, which indicates that the coiled configuration of HCNFs makes a noticeable contribution to the reinforcement of NR/CB system.

A mechanism for leader stepping

Science.gov (United States)

Ebert, U.; Carlson, B. E.; Koehn, C.

2013-12-01

The stepping of negative leaders is well observed, but not well understood. A major problem consists of the fact that the streamer corona is typically invisible within a thunderstorm, but determines the evolution of a leader. Motivated by recent observations of streamer and leader formation in the laboratory by T.M.P. Briels, S. Nijdam, P. Kochkin, A.P.J. van Deursen et al., by recent simulations of these processes by J. Teunissen, A. Sun et al., and by our theoretical understanding of the process, we suggest how laboratory phenomena can be extrapolated to lightning leaders to explain the stepping mechanism.

Acidification, not carbonation, is the major regulator of carbon fluxes in the coccolithophore Emiliania huxleyi.

Science.gov (United States)

Kottmeier, Dorothee M; Rokitta, Sebastian D; Rost, Björn

2016-07-01

A combined increase in seawater [CO2 ] and [H(+) ] was recently shown to induce a shift from photosynthetic HCO3 (-) to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source. To identify the driver of this shift, we exposed low- and high-light acclimated E. huxleyi to a matrix of two levels of dissolved inorganic carbon (1400, 2800 μmol kg(-1) ) and pH (8.15, 7.85) and directly measured cellular O2 , CO2 and HCO3 (-) fluxes under these conditions. Exposure to increased [CO2 ] had little effect on the photosynthetic fluxes, whereas increased [H(+) ] led to a significant decline in HCO3 (-) uptake. Low-light acclimated cells overcompensated for the inhibition of HCO3 (-) uptake by increasing CO2 uptake. High-light acclimated cells, relying on higher proportions of HCO3 (-) uptake, could not increase CO2 uptake and photosynthetic O2 evolution consequently became carbon-limited. These regulations indicate that OA responses in photosynthesis are caused by [H(+) ] rather than by [CO2 ]. The impaired HCO3 (-) uptake also provides a mechanistic explanation for lowered calcification under OA. Moreover, it explains the OA-dependent decrease in photosynthesis observed in high-light grown phytoplankton. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Sources and transport of carbon and nitrogen in the River Sava watershed, a major tributary of the River Danube

Energy Technology Data Exchange (ETDEWEB)

Ogrinc, Nives [Department of Environmental Science, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)], E-mail: nives.ogrinc@ijs.si; Markovics, Roland; Kanduc, Tjasa [Department of Environmental Science, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Walter, Lynn M. [Department of Geological Science, University of Michigan, 1018 C. C. Little Building, Ann Arbor, MI 48109-1063 (United States); Hamilton, Stephen K. [Kellogg Biological Station, Michigan State University, 3700 E. Gull Lake Drive, Hickory Corners, MI 49060-9516 (United States)

2008-12-15

Carbon and nitrogen dynamics were examined throughout the River Sava watershed, a major tributary of the River Danube, in 2005 and 2006. The River Sava exported 2.1 x 10{sup 11} mol C/yr as dissolved inorganic carbon (DIC), and emitted 2.5 x 10{sup 10} mol C/yr as CO{sub 2} to the atmosphere. Stable carbon isotope ratios indicate that up to 42% of DIC originated from carbonate weathering and {approx}23% from degradation of organic matter. Loads of dissolved and particulate organic carbon increased with discharge and export rates were calculated to be 2.1 x 10{sup 10} mol C/yr and up to 4.1 x 10{sup 9} mol C/yr, respectively. Isotopic compositions ({delta}{sup 13}C and {delta}{sup 15}N) and C/N ratios indicated that soil organic matter was the dominant source of particulate organic matter for 59% of the samples. Eighteen percent of the samples were dominated by plankton, 12% by periodic inputs of fresh terrestrial plant detritus with C/N > 15, and about 11% of the samples were dominated by the contribution of aquatic vascular plants. Nitrate inputs were controlled by land use in the River Sava watershed. {delta}{sup 15}N{sub NO{sub 3}} values <6 per mille were found in predominantly forested watersheds, while values >6 per mille typically represented watersheds with a higher percentage of agricultural and/or urban land use. Elevated {delta}{sup 15}N{sub NO{sub 3}} values (up to +25.5 per mille) at some sites were probably due to the combined effects of low-flow and inputs from sewage and/or animal waste.

Plasma-material Interactions in Current Tokamaks and their Implications for Next-step Fusion Reactors

International Nuclear Information System (INIS)

Federici, G.; Skinner, C.H.; Brooks, J.N.; Coad, J.P.; Grisolia, C.

2001-01-01

The major increase in discharge duration and plasma energy in a next-step DT (deuterium-tritium) fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety, and performance. Erosion will increase to a scale of several centimeters from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma-facing components. Controlling plasma wall interactions is critical to achieving high performance in present-day tokamaks and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena has stimulated an internationally coordinated effort in the field of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) project and significant progress has been made in better under standing these issues. This paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next-step fusion reactors. Two main topical groups of interactions are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation, (ii) tritium retention and removal. The use of modeling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D (Research and Development) avenues for their resolution are presented

Plasma-material Interactions in Current Tokamaks and their Implications for Next-step Fusion Reactors

Energy Technology Data Exchange (ETDEWEB)

Federici, G.; Skinner, C.H.; Brooks, J.N.; Coad, J.P.; Grisolia, C. [and others

2001-01-10

The major increase in discharge duration and plasma energy in a next-step DT [deuterium-tritium] fusion reactor will give rise to important plasma-material effects that will critically influence its operation, safety, and performance. Erosion will increase to a scale of several centimeters from being barely measurable at a micron scale in today's tokamaks. Tritium co-deposited with carbon will strongly affect the operation of machines with carbon plasma-facing components. Controlling plasma wall interactions is critical to achieving high performance in present-day tokamaks and this is likely to continue to be the case in the approach to practical fusion reactors. Recognition of the important consequences of these phenomena has stimulated an internationally coordinated effort in the field of plasma-surface interactions supporting the Engineering Design Activities of the International Thermonuclear Experimental Reactor (ITER) project and significant progress has been made in better under standing these issues. This paper reviews the underlying physical processes and the existing experimental database of plasma-material interactions both in tokamaks and laboratory simulation facilities for conditions of direct relevance to next-step fusion reactors. Two main topical groups of interactions are considered: (i) erosion/redeposition from plasma sputtering and disruptions, including dust and flake generation, (ii) tritium retention and removal. The use of modeling tools to interpret the experimental results and make projections for conditions expected in future devices is explained. Outstanding technical issues and specific recommendations on potential R and D [Research and Development] avenues for their resolution are presented.

Hidden Hydride Transfer as a Decisive Mechanistic Step in the Reactions of the Unligated Gold Carbide [AuC]+ with Methane under Ambient Conditions.

Science.gov (United States)

Li, Jilai; Zhou, Shaodong; Schlangen, Maria; Weiske, Thomas; Schwarz, Helmut

2016-10-10

The reactivity of the cationic gold carbide [AuC] + (bearing an electrophilic carbon atom) towards methane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The product pairs generated, that is, Au + /C 2 H 4 , [Au(C 2 H 2 )] + /H 2 , and [C 2 H 3 ] + /AuH, point to the breaking and making of C-H, C-C, and H-H bonds under single-collision conditions. The mechanisms of these rather efficient reactions have been elucidated by high-level quantum-chemical calculations. As a major result, based on molecular orbital and NBO-based charge analysis, an unprecedented hydride transfer from methane to the carbon atom of [AuC] + has been identified as a key step. Also, the origin of this novel mechanistic scenario has been addressed. The mechanistic insights derived from this study may provide guidance for the rational design of carbon-based catalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SPAR-H Step-by-Step Guidance

Energy Technology Data Exchange (ETDEWEB)

W. J. Galyean; A. M. Whaley; D. L. Kelly; R. L. Boring

2011-05-01

This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

SPAR-H Step-by-Step Guidance

International Nuclear Information System (INIS)

Galyean, W.J.; Whaley, A.M.; Kelly, D.L.; Boring, R.L.

2011-01-01

This guide provides step-by-step guidance on the use of the SPAR-H method for quantifying Human Failure Events (HFEs). This guide is intended to be used with the worksheets provided in: 'The SPAR-H Human Reliability Analysis Method,' NUREG/CR-6883, dated August 2005. Each step in the process of producing a Human Error Probability (HEP) is discussed. These steps are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff. The discussions on dependence are extensive and include an appendix that describes insights obtained from the psychology literature.

SPAR-H Step-by-Step Guidance

Energy Technology Data Exchange (ETDEWEB)

April M. Whaley; Dana L. Kelly; Ronald L. Boring; William J. Galyean

2012-06-01

Step-by-step guidance was developed recently at Idaho National Laboratory for the US Nuclear Regulatory Commission on the use of the Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method for quantifying Human Failure Events (HFEs). This work was done to address SPAR-H user needs, specifically requests for additional guidance on the proper application of various aspects of the methodology. This paper overviews the steps of the SPAR-H analysis process and highlights some of the most important insights gained during the development of the step-by-step directions. This supplemental guidance for analysts is applicable when plant-specific information is available, and goes beyond the general guidance provided in existing SPAR-H documentation. The steps highlighted in this paper are: Step-1, Categorizing the HFE as Diagnosis and/or Action; Step-2, Rate the Performance Shaping Factors; Step-3, Calculate PSF-Modified HEP; Step-4, Accounting for Dependence, and; Step-5, Minimum Value Cutoff.

Step-grandparenthood in the United States.

Science.gov (United States)

Yahirun, Jenjira J; Park, Sung S; Seltzer, Judith A

2018-01-18

This study provides new information about the demography of step-grandparenthood in the United States. Specifically, we examine the prevalence of step-grandparenthood across birth cohorts and for socioeconomic and racial/ethnic groups. We also examine lifetime exposure to the step-grandparent role. Using data from the Panel Study of Income Dynamics and the Health and Retirement Study, we use percentages to provide first estimates of step-grandparenthood and to describe demographic and socioeconomic variation in who is a step-grandparent. We use life tables to estimate the exposure to step-grandparenthood. The share of step-grandparents is increasing across birth cohorts. However, individuals without a college education and non-Whites are more likely to become step-grandparents. Exposure to the step-grandparent role accounts for approximately 15% of total grandparent years at age 65 for women and men. A growing body of research finds that grandparents are increasingly instrumental in the lives of younger generations. However, the majority of this work assumes that these ties are biological, with little attention paid to the role of family complexity across three generations. Understanding the demographics of step-grandparenthood sheds light on the family experiences of an overlooked, but growing segment of the older adult population in the United States. © The Author(s) 2018. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

An efficient one-step condensation and activation strategy to synthesize porous carbons with optimal micropore sizes for highly selective CO₂ adsorption.

Science.gov (United States)

Wang, Jiacheng; Liu, Qian

2014-04-21

A series of microporous carbons (MPCs) were successfully prepared by an efficient one-step condensation and activation strategy using commercially available dialdehyde and diamine as carbon sources. The resulting MPCs have large surface areas (up to 1881 m(2) g(-1)), micropore volumes (up to 0.78 cm(3) g(-1)), and narrow micropore size distributions (0.7-1.1 nm). The CO₂ uptakes of the MPCs prepared at high temperatures (700-750 °C) are higher than those prepared under mild conditions (600-650 °C), because the former samples possess optimal micropore sizes (0.7-0.8 nm) that are highly suitable for CO₂ capture due to enhanced adsorbate-adsorbent interactions. At 1 bar, MPC-750 prepared at 750 °C demonstrates the best CO₂ capture performance and can efficiently adsorb CO₂ molecules at 2.86 mmol g(-1) and 4.92 mmol g(-1) at 25 and 0 °C, respectively. In particular, the MPCs with optimal micropore sizes (0.7-0.8 nm) have extremely high CO₂/N₂ adsorption ratios (47 and 52 at 25 and 0 °C, respectively) at 1 bar, and initial CO₂/N₂ adsorption selectivities of up to 81 and 119 at 25 °C and 0 °C, respectively, which are far superior to previously reported values for various porous solids. These excellent results, combined with good adsorption capacities and efficient regeneration/recyclability, make these carbons amongst the most promising sorbents reported so far for selective CO₂ adsorption in practical applications.

Brazilian natural fiber (jute as raw material for activated carbon production

Directory of Open Access Journals (Sweden)

CARLA F.S. ROMBALDO

2014-12-01

Full Text Available Jute fiber is the second most common natural cellulose fiber worldwide, especially in recent years, due to its excellent physical, chemical and structural properties. The objective of this paper was to investigate: the thermal degradation of in natura jute fiber, and the production and characterization of the generated activated carbon. The production consisted of carbonization of the jute fiber and activation with steam. During the activation step the amorphous carbon produced in the initial carbonization step reacted with oxidizing gas, forming new pores and opening closed pores, which enhanced the adsorptive capacity of the activated carbon. N2 gas adsorption at 77K was used in order to evaluate the effect of the carbonization and activation steps. The results of the adsorption indicate the possibility of producing a porous material with a combination of microporous and mesoporous structure, depending on the parameters used in the processes, with resulting specific surface area around 470 m2.g–1. The thermal analysis indicates that above 600°C there is no significant mass loss.

Production of biovanillin by one-step biotransformation using fungus Pycnoporous cinnabarinus.

Science.gov (United States)

Tilay, Ashwini; Bule, Mahesh; Annapure, Uday

2010-04-14

The current study proposes a one-step biotransformation process for vanillin production from ferulic acid using the wild fungal strain Pycnoporous cinnabarinus belonging to the family Basidiomycete. Improvement of biotransformation conditions was performed in two steps; initially a one factor at a time method was used to investigate effects of medium composition variables (i.e., carbon, nitrogen) and environmental factors such as pH on vanillin production. Subsequently, concentrations of medium components were optimized using an orthogonal matrix method. After primary screening, glucose as carbon source and corn steep liquor and ammonium chloride as organic and inorganic nitrogen source, respectively, supported maximum biotransformation of ferulic acid to vanillin. Under statistically optimum conditions vanillin production from ferulic acid by P. cinnabarinus was 126 mg/L with a molar yield of 54%. The overall molar yield of vanillin production increased by 4 times.

Predictors of incident major depression in diabetic outpatients with subthreshold depression

DEFF Research Database (Denmark)

Bot, Mariska; Pouwer, Francois; Ormel, Johan

2010-01-01

AIMS: The objective of the study was to determine rates and risks of major depression in diabetes outpatients with subthreshold depression. METHODS: This study is based on data of a stepped care-based intervention study in which diabetic patients with subthreshold depression were randomly allocated...... to low-intensity stepped care, aimed at reducing depressive symptoms, or to care as usual. Patients had a baseline Center for Epidemiologic Studies Depression Scale (CES-D) score ≥ 16, but no baseline major depression according to the Mini International Neuropsychiatric Interview (MINI). Demographic...... major depression. Stepped care allocation was not related to incident major depression. In multivariable models, similar results were found. CONCLUSIONS: Having a higher baseline level of anxiety and depression appeared to be related to incident major depression during 2-year follow-up in diabetic...

A national look at carbon capture and storage-National carbon sequestration database and geographical information system (NatCarb)

Science.gov (United States)

Carr, T.R.; Iqbal, A.; Callaghan, N.; ,; Look, K.; Saving, S.; Nelson, K.

2009-01-01

The US Department of Energy's Regional Carbon Sequestration Partnerships (RCSPs) are responsible for generating geospatial data for the maps displayed in the Carbon Sequestration Atlas of the United States and Canada. Key geospatial data (carbon sources, potential storage sites, transportation, land use, etc.) are required for the Atlas, and for efficient implementation of carbon sequestration on a national and regional scale. The National Carbon Sequestration Database and Geographical Information System (NatCarb) is a relational database and geographic information system (GIS) that integrates carbon storage data generated and maintained by the RCSPs and various other sources. The purpose of NatCarb is to provide a national view of the carbon capture and storage potential in the U.S. and Canada. The digital spatial database allows users to estimate the amount of CO2 emitted by sources (such as power plants, refineries and other fossil-fuel-consuming industries) in relation to geologic formations that can provide safe, secure storage sites over long periods of time. The NatCarb project is working to provide all stakeholders with improved online tools for the display and analysis of CO2 carbon capture and storage data. NatCarb is organizing and enhancing the critical information about CO2 sources and developing the technology needed to access, query, model, analyze, display, and distribute natural resource data related to carbon management. Data are generated, maintained and enhanced locally at the RCSP level, or at specialized data warehouses, and assembled, accessed, and analyzed in real-time through a single geoportal. NatCarb is a functional demonstration of distributed data-management systems that cross the boundaries between institutions and geographic areas. It forms the first step toward a functioning National Carbon Cyberinfrastructure (NCCI). NatCarb provides access to first-order information to evaluate the costs, economic potential and societal issues of

Syntheses of protoporphyrin-IX regioselectivity carbon-13 labelled at the alpha-vinyl carbons

International Nuclear Information System (INIS)

Smith, K.M.; Fujinari, E.M.

1986-01-01

A method for transformation of readily available beta-vinyl 99% carbon-13 enriched derivatives of protoporphyrin-IX dimethyl ester into the less accessible alpha-vinyl labelled isomers is described. The procedure involves thallium(III) promoted vinyl carbon rearrangement, and proceeds through 2,2-dimethoxyethyl, formylmethyl, 2-hydroxyethyl and 2-chloroethyl porphyrins; the rearranged vinyl groups are regenerated from 2-chloroethyl in the last step by treatment with base. No evidence of vinyl carbon scrambling in the sequence is observed, and spectroscopic data of the products are given. (author)

Mesoporous-activated carbon prepared from chitosan flakes via single-step sodium hydroxide activation for the adsorption of methylene blue.

Science.gov (United States)

Marrakchi, F; Ahmed, M J; Khanday, W A; Asif, M; Hameed, B H

2017-05-01

In this work, mesoporous-activated carbon (CSAC) was prepared from chitosan flakes (CS) via single-step sodium hydroxide activation for the adsorption of methylene blue (MB). CSAC was prepared using different impregnation ratios of NaOH:CS (1:1, 2:1, 3:1, and 4:1) at 800°C for 90min. The adsorption performance of CSAC was evaluated for MB at different adsorption variables, such MB initial concentrations (25-400mg/L), solution pH (3-11), and temperature (30-50°C). The adsorption isotherm data of CSAC-MB were well fitted to Langmuir model with a maximum adsorption capacity 143.53mg/g at 50°C. Best representation of kinetic data was obtained by the pseudo-second order model. CSAC exhibited excellent adsorption uptake for MB and can potentially be used for other cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication of carbon quantum dots with nano-defined position and pattern in one step via sugar-electron-beam writing.

Science.gov (United States)

Weng, Yuyan; Li, Zhiyun; Peng, Lun; Zhang, Weidong; Chen, Gaojian

2017-12-14

Quantum dots (QDs) are promising materials in nanophotonics, biological imaging, and even quantum computing. Precise positioning and patterning of QDs is a prerequisite for realizing their actual applications. Contrary to the traditional two discrete steps of fabricating and positioning QDs, herein, a novel sugar-electron-beam writing (SEW) method is reported for producing QDs via electron-beam lithography (EBL) that uses a carefully chosen synthetic resist, poly(2-(methacrylamido)glucopyranose) (PMAG). Carbon QDs (CQDs) could be fabricated in situ through electron beam exposure, and the nanoscale position and luminescence intensity of the produced CQDs could be precisely controlled without the assistance of any other fluorescent matter. We have demonstrated that upon combining an electron beam with a glycopolymer, in situ production of CQDs occurs at the electron beam spot center with nanoscale precision at any place and with any patterns, an advancement that we believe will stimulate innovations in future applications.

A DIGE analysis of developing poplar leaves subjected to ozone reveals major changes in carbon metabolism.

Science.gov (United States)

Bohler, Sacha; Bagard, Matthieu; Oufir, Mouhssin; Planchon, Sébastien; Hoffmann, Lucien; Jolivet, Yves; Hausman, Jean-François; Dizengremel, Pierre; Renaut, Jenny

2007-05-01

Tropospheric ozone pollution is described as having major negative effects on plants, compromising plant survival. Carbon metabolism is especially affected. In the present work, the effects of chronic ozone exposure were evaluated at the proteomic level in developing leaves of young poplar plants exposed to 120 ppb of ozone for 35 days. Soluble proteins (excluding intrinsic membrane proteins) were extracted from leaves after 3, 14 and 35 days of ozone exposure, as well as 10 days after a recovery period. Proteins (pI 4 to 7) were analyzed by 2-D DIGE experiments, followed by MALDI-TOF-TOF identification. Additional observations were obtained on growth, lesion formation, and leaf pigments analysis. Although treated plants showed large necrotic spots and chlorosis in mature leaves, growth decreased only slightly and plant height was not affected. The number of abscised leaves was higher in treated plants, but new leaf formation was not affected. A decrease in chlorophylls and lutein contents was recorded. A large number of proteins involved in carbon metabolism were identified. In particular, proteins associated with the Calvin cycle and electron transport in the chloroplast were down-regulated. In contrast, proteins associated with glucose catabolism increased in response to ozone exposure. Other identified enzymes are associated with protein folding, nitrogen metabolism and oxidoreductase activity.

Carbon for sensing devices

CERN Document Server

Tagliaferro, Alberto

2015-01-01

This book reveals why carbon is playing such an increasingly prominent role as a sensing material. The various steps that transform a raw material in a sensing device are thoroughly presented and critically discussed.  The authors deal with all aspects of carbon-based sensors, starting from the various hybridization and allotropes of carbon, with specific focus on micro and nanosized carbons (e.g., carbon nanotubes, graphene) and their growth processes. The discussion then moves to the role of functionalization and the different routes to achieve it. Finally, a number of sensing applications in various fields are presented, highlighting the connection with the basic properties of the various carbon allotropes.  Readers will benefit from this book’s bottom-up approach, which starts from the local bonding in carbon solids and ends with sensing applications, linking the local hybridization of carbon atoms and its modification by functionalization to specific device performance. This book is a must-have in th...

Changes of global terrestrial carbon budget and major drivers in recent 30 years simulated using the remote sensing driven BEPS model

Science.gov (United States)

Ju, W.; Chen, J.; Liu, R.; Liu, Y.

2013-12-01

The process-based Boreal Ecosystem Productivity Simulator (BEPS) model was employed in conjunction with spatially distributed leaf area index (LAI), land cover, soil, and climate data to simulate the carbon budget of global terrestrial ecosystems during the period from 1981 to 2008. The BEPS model was first calibrated and validated using gross primary productivity (GPP), net primary productivity (NPP), and net ecosystem productivity (NEP) measured in different ecosystems across the word. Then, four global simulations were conducted at daily time steps and a spatial resolution of 8 km to quantify the global terrestrial carbon budget and to identify the relative contributions of changes in climate, atmospheric CO2 concentration, and LAI to the global terrestrial carbon sink. The long term LAI data used to drive the model was generated through fusing Moderate Resolution Imaging Spectroradiometer (MODIS) and historical Advanced Very High Resolution Radiometer (AVHRR) data pixel by pixel. The meteorological fields were interpolated from the 0.5° global daily meteorological dataset produced by the land surface hydrological research group at Princeton University. The results show that the BEPS model was able to simulate carbon fluxes in different ecosystems. Simulated GPP, NPP, and NEP values and their temporal trends exhibited distinguishable spatial patterns. During the period from 1981 to 2008, global terrestrial ecosystems acted as a carbon sink. The averaged global totals of GPP NPP, and NEP were 122.70 Pg C yr-1, 56.89 Pg C yr-1, and 2.76 Pg C yr-1, respectively. The global totals of GPP and NPP increased greatly, at rates of 0.43 Pg C yr-2 (R2=0.728) and 0.26 Pg C yr-2 (R2=0.709), respectively. Global total NEP did not show an apparent increasing trend (R2= 0.036), averaged 2.26 Pg C yr-1, 3.21 Pg C yr-1, and 2.72 Pg C yr-1 for the periods from 1981 to 1989, from 1990 to 1999, and from 2000 to 2008, respectively. The magnitude and temporal trend of global

Synthesis of carbon-14 labeled vigabatrin. [Antieplileptic

Energy Technology Data Exchange (ETDEWEB)

Schuster, A.J.; Wagner, E.R. (Marion Merrell Dow Inc, Indianapolis, IN (United States))

1993-01-01

Carbon-14 labeled vigabatrin was synthesized in 5 steps from 5-hydroxymethyl-2-pyrrolidone tosylate and NaCN-[[sup 14]C]. A key step involved reduction of the resulting nitrile in the presence of excess dimethylamine to give the dimethylamino-ethyl 2-pyrrolidone derivative in one step. This afforded an overall radiochemical yield of 22% and radiochemical purity greater than 98%. (Author).

Determining Inorganic and Organic Carbon.

Science.gov (United States)

Koistinen, Jaana; Sjöblom, Mervi; Spilling, Kristian

2017-11-21

Carbon is the element which makes up the major fraction of lipids and carbohydrates, which could be used for making biofuel. It is therefore important to provide enough carbon and also follow the flow into particulate organic carbon and potential loss to dissolved organic forms of carbon. Here we present methods for determining dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon.

A new method for rapid determination of carbohydrate and total carbon concentrations using UV spectrophotometry.

Science.gov (United States)

Albalasmeh, Ammar A; Berhe, Asmeret Asefaw; Ghezzehei, Teamrat A

2013-09-12

A new UV spectrophotometry based method for determining the concentration and carbon content of carbohydrate solution was developed. This method depends on the inherent UV absorption potential of hydrolysis byproducts of carbohydrates formed by reaction with concentrated sulfuric acid (furfural derivatives). The proposed method is a major improvement over the widely used Phenol-Sulfuric Acid method developed by DuBois, Gilles, Hamilton, Rebers, and Smith (1956). In the old method, furfural is allowed to develop color by reaction with phenol and its concentration is detected by visible light absorption. Here we present a method that eliminates the coloration step and avoids the health and environmental hazards associated with phenol use. In addition, avoidance of this step was shown to improve measurement accuracy while significantly reducing waiting time prior to light absorption reading. The carbohydrates for which concentrations and carbon content can be reliably estimated with this new rapid Sulfuric Acid-UV technique include: monosaccharides, disaccharides and polysaccharides with very high molecular weight. Copyright © 2013 Elsevier Ltd. All rights reserved.

Element fractionation by sequential extraction in a soil with high carbonate content

International Nuclear Information System (INIS)

Sulkowski, Margareta; Hirner, Alfred V.

2006-01-01

The influence of carbonate and other buffering substances in soils on the results of a 3-step sequential extraction procedure (BCR) used for metal fractionation was investigated. Deviating from the original extraction scheme, where the extracts are analysed only for a limited number of metals, almost all elements in the soils were quantified by X-ray fluorescence spectroscopy, in the initial samples as well as in the residues of all extraction steps. Additionally, the mineral contents were determined by X-ray diffractometry. Using this methodology, it was possible to correlate changes in soil composition caused by the extraction procedure with the release of elements. Furthermore, the pH values of all extracts were monitored, and certain extraction steps were repeated until no significant pH-rise occurred. A soil with high dolomite content (27%) and a carbonate free soil were extracted. Applying the original BCR-sequence to the calcareous soil, carbonate was found in the residues of the first two steps and extract pH-values rose by around two units in the first and second step, caused mainly by carbonate dissolution. This led to wrong assignment of the carbonate elements Ca, Mg, Sr, Ba, and also to decreased desorption and increased re-adsorption of ions in those steps. After repetition of the acetic acid step until extract pH remained low, the carbonate was completely destroyed and the distributions of the elements Ca, Mg, Sr, Ba as well as those of Co, Ni, Cu, Zn and Pb were found to be quite different to those determined in the original extraction. Furthermore, it could be shown that the effectiveness of the reduction process in step two was reduced by increasing pH: Fe oxides were not significantly attacked by the repeated acetic acid treatments, but a 10-fold amount of Fe was mobilized by hydroxylamine hydrochloride after complete carbonate destruction. On the other hand, only small amounts of Fe were released anyway. Even repeated reduction steps did not

Carbon fiber manufacturing via plasma technology

Science.gov (United States)

Paulauskas, Felix L.; Yarborough, Kenneth D.; Meek, Thomas T.

2002-01-01

The disclosed invention introduces a novel method of manufacturing carbon and/or graphite fibers that avoids the high costs associated with conventional carbonization processes. The method of the present invention avoids these costs by utilizing plasma technology in connection with electromagnetic radiation to produce carbon and/or graphite fibers from fully or partially stabilized carbon fiber precursors. In general, the stabilized or partially stabilized carbon fiber precursors are placed under slight tension, in an oxygen-free atmosphere, and carbonized using a plasma and electromagnetic radiation having a power input which is increased as the fibers become more carbonized and progress towards a final carbon or graphite product. In an additional step, the final carbon or graphite product may be surface treated with an oxygen-plasma treatment to enhance adhesion to matrix materials.

Interaction of carbon dioxide with Cu overlayers on Pt(111)

DEFF Research Database (Denmark)

Schumacher, N.; Andersson, Klas Jerker; Grabow, L.C.

2008-01-01

Experimental and theoretical studies on the interaction of carbon dioxide with pseudomorphic and rough copper layers deposited on a platinum (111) single crystal are reported. Evidence for carbon dioxide dissociation and carbonate formation is presented and the relevance to methanol synthesis......) reveals a broad high temperature desorption state for CO2 with peak maximum around 450 K. X-ray photoelectron spectroscopy (XPS) shows that approximately one third of the oxygen accumulated on the surface upon CO2 exposure remains after TPD, indicative of carbonate formation via CO2 dissociation supplying...... O-ads and then facile CO2 + O-ads association, as well as subsequent decomposition at higher temperatures. Density functional theory studies of stepped Cu and Cu/Pt slabs reproduce vibrational frequencies of the carbonate, suggesting a nearly flat tridentate configuration at steps/defect sites....

The biosynthesis of nitrogen-, sulfur-, and high-carbon chain-containing sugars.

Science.gov (United States)

Lin, Chia-I; McCarty, Reid M; Liu, Hung-wen

2013-05-21

Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and "high-carbon" chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered "rare" due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains.

One-step Conversion of Levulinic Acid to Succinic Acid Using I2/t-BuOK System: The Iodoform Reaction Revisited.

Science.gov (United States)

Kawasumi, Ryosuke; Narita, Shodai; Miyamoto, Kazunori; Tominaga, Ken-Ichi; Takita, Ryo; Uchiyama, Masanobu

2017-12-21

The iodoform reaction has long been used as a qualitative test for acetyl and/or ethanol units in organic molecules. However, its synthetic applications are quite limited. Here, we describe a tuned iodoform reaction for oxidative demethylation reaction with I 2 and t-BuOK in t-BuOH, in which in situ-generated t-BuOI serves as the chemoselective iodinating agent. This system enables one-step conversion of levulinic acid to succinic acid, a major four-carbon chemical feedstock. This oxidative demethylation is also applicable to other compounds containing an acetyl group/ethanol unit, affording the corresponding carboxylic acids in a selective manner.

Very short functionalized carbon nanotubes for membrane applications

NARCIS (Netherlands)

Fonseca, A.; Reijerkerk, Sander; Potreck, Jens; Nijmeijer, Dorothea C.; Mekhalif, Z.; Delhalle, J.

2010-01-01

The cutting and functionalization of carbon nanotubes is described, applying a single-step ball-mill based process. Very short carbon nanotubes bearing primary amine functions were produced, characterized and incorporated in polymeric membranes. The gas separation performance of the composite

Sugar-starvation-induced changes of carbon metabolism in excised maize root tips

International Nuclear Information System (INIS)

Dieuaide-Noubhani, M.; Canioni, P.; Raymond, P.

1997-01-01

Excised maize (Zea mays L.) root tips were used to study the early metabolic effects of glucose (Glc) starvation. Root tips were prelabeled with [1-13C]Glc so that carbohydrates and metabolic intermediates were close to steady-state labeling, but lipids and proteins were scarcely labeled. They were then incubated in a sugar-deprived medium for carbon starvation. Changes in the level of soluble sugars, the respiratory quotient, and the 13C enrichment of intermediates, as measured by 13C and 1H nuclear magnetic resonance, were studied to detect changes in carbon fluxes through glycolysis and the tricarboxylic acid cycle. Labeling of glutamate carbons revealed two major changes in carbon input into the tricarboxylic acid cycle: (a) the phosphoenolpyruvate carboxylase flux stopped early after the start of Glc starvation, and (b) the contribution of glycolysis as the source of acetyl-coenzyme A for respiration decreased progressively, indicating an increasing contribution of the catabolism of protein amino acids, fatty acids, or both. The enrichment of glutamate carbons gave no evidence for proteolysis in the early steps of starvation, indicating that the catabolism of proteins was delayed compared with that of fatty acids. Labeling of carbohydrates showed that sucrose turnover continues during sugar starvation, but gave no indication for any significant flux through gluconeogenesis

New Step Underground in Universe Origins Quest

CERN Document Server

Evans, Robert

2003-01-01

Europe's top particle physics research center has taken a major step in its plan to build the world's biggest "particle smasher" which it hopes will eventually unlock the secrets of the origins of the universe (½ page)

Step out - Step in Sequencing Games

NARCIS (Netherlands)

Musegaas, M.; Borm, P.E.M.; Quant, M.

2014-01-01

In this paper a new class of relaxed sequencing games is introduced: the class of Step out - Step in sequencing games. In this relaxation any player within a coalition is allowed to step out from his position in the processing order and to step in at any position later in the processing order.

Mineral CO2 sequestration by steel slag carbonation

International Nuclear Information System (INIS)

Huijgen, W.J.J.; Comans, R.N.J.; Witkamp, G.J.

2005-12-01

Mineral CO2 sequestration, i.e., carbonation of alkaline silicate Ca/Mg minerals, analogous to natural weathering processes, is a possible technology for the reduction of carbon dioxide emissions to the atmosphere. In this paper, alkaline Ca-rich industrial residues are presented as a possible feedstock for mineral CO2 sequestration. These materials are cheap, available near large point sources of CO2, and tend to react relatively rapidly with CO2 due to their chemical instability. Ground steel slag was carbonated in aqueous suspensions to study its reaction mechanisms. Process variables, such as particle size, temperature, carbon dioxide pressure, and reaction time, were systematically varied, and their influence on the carbonation rate was investigated. The maximum carbonation degree reached was 74% of the Ca content in 30 min at 19 bar pressure, 100C, and a particle size of <38 μm. The two must important factors determining the reaction rare are particle size (<2 mm to <38 μm) and reaction temperature (25-225C). The carbonation reaction was found to occur in two steps: (1) leaching of calcium from the steel slag particles into the solution; (2) precipitation of calcite on the surface of these particles. The first step and, more in particular, the diffusion of calcium through the solid matrix toward the surface appeared to be the rate-determining reaction step, The Ca diffusion was found to be hindered by the formation of a CaCO3-coating and a Ca-depleted silicate zona during the carbonation process. Research on further enhancement of the reaction rate, which would contribute to the development of a cost-effective CO2-sequestration process, should focus particularly on this mechanism

Step out-step in sequencing games

NARCIS (Netherlands)

Musegaas, Marieke; Borm, Peter; Quant, Marieke

2015-01-01

In this paper a new class of relaxed sequencing games is introduced: the class of Step out–Step in sequencing games. In this relaxation any player within a coalition is allowed to step out from his position in the processing order and to step in at any position later in the processing order. First,

ONE STEP GREEN SYNTHESIS OF CARBON QUANTUM DOTS AND ITS APPLICATION TOWARDS THE BIOELECTROANALYTICAL AND BIOLABELING STUDIES

International Nuclear Information System (INIS)

Shereema, Rayammarakkar M.; Sankar, Vandana; Raghu, K.G; Rao, Talasila P.; Shankar, S.Sharath

2015-01-01

Highlights: • A green method was adopted for the synthesis of carbon quantum dots. • Being green fluorescent it was used for the cell imaging. • The carbon paste based carbon quantum dot was fabricated. • This quantum dots/carbon paste electrode was found to be capable of detecting dopamine in the nano molar level. • Possible interference from ascorbic acid and uric acid was successfully eliminated by the fabricated electrode. - Abstract: A green luminescent carbon quantum dots were prepared from maltose by Microwave assisted method followed by passivation with NaOH (pH = 7.4). The TEM measurement confirmed the average size of prepared carbon quantum dots to be 2 nm. Surface characterization such as XPS, FTIR and Raman spectroscopy confirm that the functional groups (C=O, C-OH) were attached on the surface of sp 2 hybridized carbon. Electrochemical characterization studies on carbon paste electrode (CPE) revealed that the synthesized carbon quantum dots showed higher electrocatalytic property, conductivity and surface area. Therefore, herein we report the synthesized carbon quantum dots could find its applicability as an electrochemical sensor for the detection of neurotransmitter, dopamine. Cyclic voltammetry and differential pulse voltammetry (DPV) was employed for the detection of DA in presence of common interferences like UA, and AA with carbon quantum dots modified carbon paste electrode. The developed sensor was effectively applied for the real sample analysis with satisfactory results. Moreover, biological studies in He La cell lines proclaimed that the cell viability was unaffected (100% viability) on incubation with the carbon dots. Significant cellular uptake as revealed by fluorescence imaging makes them suitable for cell labeling studies.

In Situ One-Step Synthesis of Hierarchical Nitrogen-Doped Porous Carbon for High Performance Supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Jeon, Ju Won [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Texas A & M Univ., College Station, TX (United States); Sharma, Ronish [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Meduri, Praveen [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Arey, Bruce W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schaef, Herbert T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lutkenhaus, Jodie [Texas A & M Univ., College Station, TX (United States); Lemmon, John P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, Praveen K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nandasiri, Manjula I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); McGrail, B. Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nune, Satish K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-04-30

Electrochemical performance of the existing state-of-the art capacitors is not very high, key scientific barrier is that its charge storage mechanism wholly depends on adsorption of electrolyte on electrode. We present a novel method for the synthesis of nitrogen -doped porous carbons and address the drawback by precisely controlling composition and surface area. Nitrogen-doped porous carbon was synthesized using a self-sacrificial template technique without any additional nitrogen and carbon sources. They exhibited exceptionally high capacitance (239 Fg-1) due to additional pseudocapacitance originating from doped nitrogen. Cycling tests showed no obvious capacitance decay even after 10,000 cycles, which meets the requirement of commercial supercapacitors. Our method is simple and highly efficient for the production of large quantities of nitrogen-doped porous carbons.

Pyrolytic carbon black composite and method of making the same

Energy Technology Data Exchange (ETDEWEB)

Naskar, Amit K.; Paranthaman, Mariappan Parans; Bi, Zhonghe

2016-09-13

A method of recovering carbon black includes the step of providing a carbonaceous source material containing carbon black. The carbonaceous source material is contacted with a sulfonation bath to produce a sulfonated material. The sulfonated material is pyrolyzed to produce a carbon black containing product comprising a glassy carbon matrix phase having carbon black dispersed therein. A method of making a battery electrode is also disclosed.

EDTA modified glassy carbon electrode: Preparation and characterization

International Nuclear Information System (INIS)

Ustuendag, Zafer; Solak, Ali Osman

2009-01-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){2-[bis(carboxymethyl)amino]-ethyl}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb 2+ ions was investigated if this electrode could be used as a metal sensor.

Teaching Quantitative Reasoning for Nonscience Majors through Carbon Footprint Analysis

Science.gov (United States)

Boose, David L.

2014-01-01

Quantitative reasoning is a key intellectual skill, applicable across disciplines and best taught in the context of authentic, relevant problems. Here, I describe and assess a laboratory exercise that has students calculate their "carbon footprint" and evaluate the impacts of various behavior choices on that footprint. Students gather…

Multilayer oxidation resistant coating for SiC coated carbon/carbon composites at high temperature

International Nuclear Information System (INIS)

Li Hejun; Jiao Gengsheng; Li Kezhi; Wang Chuang

2008-01-01

To prevent carbon/carbon (C/C) composites from oxidation, a multilayer coating based on molybdenum disilicide and titanium disilicide was formed using a two-step pack cementation technique in argon atmosphere. XRD and SEM analysis showed that the internal coating was a bond SiC layer that acts as a buffer layer, and that the external multilayer coating formed in the two-step pack cementation was composed of two MoSi 2 -TiSi 2 -SiC layers. This coating, which is characterized by excellent thermal shock resistance, could effectively protect the composites from exposure to an oxidizing atmosphere at 1773 K for 79 h. The oxidation of the coated C/C composites was primarily due to the reaction of C/C matrix and oxygen diffusing through the penetrable cracks in the coating

Proposal to realize a cost breakthrough in carbon-13 production by photochemical separation

International Nuclear Information System (INIS)

Marling, J.B.

1979-10-01

A cost breakthrough can now be made in photochemical production of the rare stable isotope carbon-13. This cost breakthrough is achieved by CO 2 laser infrared multiple-photon dissociation of any of several halocarbons (Freon derivatives) such as CF 3 Cl, CF 3 Br, or CF 2 Cl 2 . The single-step carbon-13 enrichment factor for this process is approximately 50, yielding 30% pure C-13 in one step, or up to 97% pure C-13 in two steps. A three-fold carbon-13 cost reduction to below $20/gram is expected to be achieved in a small laboratory-scale demonstration facility capable of producing 4 to 8 kg/year of carbon-13, using presently available pulsed CO 2 TEA lasers at an average power level of 50 watts. Personnel costs dominate the attainable C-13 production costs in a small photochemical enrichment facility. A price reduction to $2/gm carbon-13 is feasible at carbon-13 production levels of 100 to 1000 kg/year, dominated by the Freon raw material costs

Development of a One-Step Multiplex PCR Assay for Differential Detection of Major Mycobacterium Species.

Science.gov (United States)

Chae, Hansong; Han, Seung Jung; Kim, Su-Young; Ki, Chang-Seok; Huh, Hee Jae; Yong, Dongeun; Koh, Won-Jung; Shin, Sung Jae

2017-09-01

The prevalence of tuberculosis continues to be high, and nontuberculous mycobacterial (NTM) infection has also emerged worldwide. Moreover, differential and accurate identification of mycobacteria to the species or subspecies level is an unmet clinical need. Here, we developed a one-step multiplex PCR assay using whole-genome analysis and bioinformatics to identify novel molecular targets. The aims of this assay were to (i) discriminate between the Mycobacterium tuberculosis complex (MTBC) and NTM using rv0577 or RD750, (ii) differentiate M. tuberculosis ( M. tuberculosis ) from MTBC using RD9, (iii) selectively identify the widespread M. tuberculosis Beijing genotype by targeting mtbk_20680 , and (iv) simultaneously detect five clinically important NTM ( M. avium , M. intracellulare , M. abscessus , M. massiliense , and M. kansasii ) by targeting IS 1311 , DT1, mass_3210 , and mkan_rs12360 An initial evaluation of the multiplex PCR assay using reference strains demonstrated 100% specificity for the targeted Mycobacterium species. Analytical sensitivity ranged from 1 to 10 pg for extracted DNA and was 10 3 and 10 4 CFU for pure cultures and nonhomogenized artificial sputum cultures, respectively, of the targeted species. The accuracy of the multiplex PCR assay was further evaluated using 55 reference strains and 94 mycobacterial clinical isolates. Spoligotyping, multilocus sequence analysis, and a commercial real-time PCR assay were employed as standard assays to evaluate the multiplex PCR assay with clinical M. tuberculosis and NTM isolates. The PCR assay displayed 100% identification agreement with the standard assays. Our multiplex PCR assay is a simple, convenient, and reliable technique for differential identification of MTBC, M. tuberculosis , M. tuberculosis Beijing genotype, and major NTM species. Copyright © 2017 American Society for Microbiology.

Method for fabricating carbon/lithium-ion electrode for rechargeable lithium cell

Science.gov (United States)

Huang, Chen-Kuo (Inventor); Surampudi, Subbarao (Inventor); Attia, Alan I. (Inventor); Halpert, Gerald (Inventor)

1995-01-01

The method includes steps for forming a carbon electrode composed of graphitic carbon particles adhered by an ethylene propylene diene monomer binder. An effective binder composition is disclosed for achieving a carbon electrode capable of subsequent intercalation by lithium ions. The method also includes steps for reacting the carbon electrode with lithium ions to incorporate lithium ions into graphitic carbon particles of the electrode. An electrical current is repeatedly applied to the carbon electrode to initially cause a surface reaction between the lithium ions and to the carbon and subsequently cause intercalation of the lithium ions into crystalline layers of the graphitic carbon particles. With repeated application of the electrical current, intercalation is achieved to near a theoretical maximum. Two differing multi-stage intercalation processes are disclosed. In the first, a fixed current is reapplied. In the second, a high current is initially applied, followed by a single subsequent lower current stage. Resulting carbon/lithium-ion electrodes are well suited for use as an anode in a reversible, ambient temperature, lithium cell.

Carbon flow analysis and Carbon emission reduction of FCC in Chinese oil refineries

Science.gov (United States)

Jia, Fengrui; Wei, Na; Ma, Danzhu; Liu, Guangxin; Wu, Ming; Yue, Qiang

2017-08-01

The major problem of the energy production in oil refineries is the high emission of CO2 in China. The fluid catalytic cracking unit (FCC) is the key source of carbon emission in the oil refineries. According to the statistical data, the carbon emission of FCC unit accounts for more than 31% for the typical oil refineries. The carbon flow of FCC in the typical Chinese oil refineries were evaluated and analysed, which aimed at the solution of CO2 emission reduction. The method of substances flow analysis (SFA) and the mathematical programming were used to evaluate the carbon metabolism and optimize the carbon emission. The results indicated that the combustion emission of the reaction-regeneration subsystem (RRS) was the major source of FCC. The quantity of CO2 emission of RSS was more than 90%. The combustion efficiency and the amount of residual oil affected the carbon emission of RRS most according to the optimized analysis of carbon emission reduction. Moreover, the fractionation subsystem (TFS) had the highest environmental efficiency and the absorption-stabilization subsystem (ASS) had the highest resource efficiency (approximately to 1) of carbon.

Geochemistry of sedimentary carbonates

National Research Council Canada - National Science Library

Morse, John W; Mackenzie, Fred T

1990-01-01

.... The last major section is two chapters on the global cycle of carbon and human intervention, and the role of sedimentary carbonates as indicators of stability and changes in Earth's surface environment...

Two-step gasification of cattle manure for hydrogen-rich gas production: Effect of biochar preparation temperature and gasification temperature.

Science.gov (United States)

Xin, Ya; Cao, Hongliang; Yuan, Qiaoxia; Wang, Dianlong

2017-10-01

Two-step gasification process was proposed to dispose cattle manure for hydrogen rich gas production. The effect of temperature on product distribution and biochar properties were first studied in the pyrolysis-carbonization process. The steam gasification of biochar derived from different pyrolysis-carbonization temperatures was then performed at 750°C and 850°C. The biochar from the pyrolysis-carbonization temperatures of 500°C had high carbon content and low volatiles content. According to the results of gasification stage, the pyrolysis-carbonization temperature of 500°C and the gasification temperature of 850°C were identified as the suitable conditions for hydrogen production. We obtained 1.61m 3 /kg of syngas production, 0.93m 3 /kg of hydrogen yield and 57.58% of hydrogen concentration. This study shows that two-step gasification is an efficient waste-to-hydrogen energy process. Copyright © 2017 Elsevier Ltd. All rights reserved.

How energetic and environmental constraints of microorganisms determine the carbon turnover in soils

Science.gov (United States)

Don, A.; Rödenbeck, C.; Gleixner, G.

2012-04-01

Microorganisms are the main catalysts driving carbon fluxes from soils. Traditional concepts of soil carbon stabilization failed to account for environmental and energy constraints of microorganisms. The distribution and density of organic carbon in the soil profile maybe a key factor determining the carbon stability and carbon flux. Decomposition is a two-step process following the Michaelis Menten kinetics: In a first step enzyme and substrate form a joint complex and then the decomposition reaction is catalyzed. Thus, biological decomposition relies on the encounter of substrate and the degradation catalyst, the microorganisms. Lower substrate concentration decreases the likelihood of an enzyme to hit a substrate molecule, to form an enzyme-substrate complex, and thus to catalyze the reaction. However, it was unproofen if this concept can be appliued to soils also. A long-term lab experiment revealed that the soil carbon turnover decreased with increasing carbon dilution due to mixture with soil minerals. The ability of microorganisms to move towards substrate in soils seems to be limited. To elucidate the effect of concentration-controlled carbon turnover, we devised the simple simulation model SCAMP based on the two-step kinetic with microorganism and carbon particles been simulated explicitly. The SCAMP model was able to simulate soil carbon profiles and age profiles in a realistic manner. The only carbon stabilization mechanism implemented in the model is the distribution of microorganisms and carbon particles in the soil and thus the availability of carbon for microorganism, which is especially important for subsoil carbon dynamics. The experiments and the model help to explain why large fractions of soil carbon have been stabilized for millennia and decoupled from the global carbon cycle.

Carbon film electrodes for super capacitor applications

Science.gov (United States)

Tan, Ming X.

1999-01-01

A microporous carbon film for use as electrodes in energy strorage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm.sup.2 and 1 g/cm.sup.2 and a gravimetric capacitance of about between 120 F/g and 315 F/g.

Effects of walking speed on the step-by-step control of step width.

Science.gov (United States)

Stimpson, Katy H; Heitkamp, Lauren N; Horne, Joscelyn S; Dean, Jesse C

2018-02-08

Young, healthy adults walking at typical preferred speeds use step-by-step adjustments of step width to appropriately redirect their center of mass motion and ensure mediolateral stability. However, it is presently unclear whether this control strategy is retained when walking at the slower speeds preferred by many clinical populations. We investigated whether the typical stabilization strategy is influenced by walking speed. Twelve young, neurologically intact participants walked on a treadmill at a range of prescribed speeds (0.2-1.2 m/s). The mediolateral stabilization strategy was quantified as the proportion of step width variance predicted by the mechanical state of the pelvis throughout a step (calculated as R 2 magnitude from a multiple linear regression). Our ability to accurately predict the upcoming step width increased over the course of a step. The strength of the relationship between step width and pelvis mechanics at the start of a step was reduced at slower speeds. However, these speed-dependent differences largely disappeared by the end of a step, other than at the slowest walking speed (0.2 m/s). These results suggest that mechanics-dependent adjustments in step width are a consistent component of healthy gait across speeds and contexts. However, slower walking speeds may ease this control by allowing mediolateral repositioning of the swing leg to occur later in a step, thus encouraging slower walking among clinical populations with limited sensorimotor control. Published by Elsevier Ltd.

Methods for Shortening and Extending the Carbon Chain in Carbohydrates

DEFF Research Database (Denmark)

Monrad, Rune Nygaard

2008-01-01

in this thesis focuses on the development and application of transition metal mediated methods for shortening and extending the carbon chain in carbohydrates thereby providing access to lower and higher sugars.A new catalytic procedure for shortening unprotected sugars by one carbon atom has been developed....... The procedure has been employed as the key step in a short five-step synthesis of the unnatural sugar L-threose in 74% overall yield from D-glucose. A zinc-mediated one-pot fragmentation-allylation reaction has been used to elongate D-glucose and D-ribose by three carbon atoms thereby producing carbohydrate......-derived α,ω-dienes, which have been converted into the natural products calystegine A3 and gabosine A. The glycosidase inhibitor calystegine A3 was produced by two similar routes from commercially available methyl α-D-glucopyranoside in 13 and 14 steps with 8.3 and 5.3% overall yield, respectively...

Trading forest carbon - OSU

Science.gov (United States)

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

Toward the prediction of class I and II mouse major histocompatibility complex-peptide-binding affinity: in silico bioinformatic step-by-step guide using quantitative structure-activity relationships.

Science.gov (United States)

Hattotuwagama, Channa K; Doytchinova, Irini A; Flower, Darren R

2007-01-01

Quantitative structure-activity relationship (QSAR) analysis is a cornerstone of modern informatics. Predictive computational models of peptide-major histocompatibility complex (MHC)-binding affinity based on QSAR technology have now become important components of modern computational immunovaccinology. Historically, such approaches have been built around semiqualitative, classification methods, but these are now giving way to quantitative regression methods. We review three methods--a 2D-QSAR additive-partial least squares (PLS) and a 3D-QSAR comparative molecular similarity index analysis (CoMSIA) method--which can identify the sequence dependence of peptide-binding specificity for various class I MHC alleles from the reported binding affinities (IC50) of peptide sets. The third method is an iterative self-consistent (ISC) PLS-based additive method, which is a recently developed extension to the additive method for the affinity prediction of class II peptides. The QSAR methods presented here have established themselves as immunoinformatic techniques complementary to existing methodology, useful in the quantitative prediction of binding affinity: current methods for the in silico identification of T-cell epitopes (which form the basis of many vaccines, diagnostics, and reagents) rely on the accurate computational prediction of peptide-MHC affinity. We have reviewed various human and mouse class I and class II allele models. Studied alleles comprise HLA-A*0101, HLA-A*0201, HLA-A*0202, HLA-A*0203, HLA-A*0206, HLA-A*0301, HLA-A*1101, HLA-A*3101, HLA-A*6801, HLA-A*6802, HLA-B*3501, H2-K(k), H2-K(b), H2-D(b) HLA-DRB1*0101, HLA-DRB1*0401, HLA-DRB1*0701, I-A(b), I-A(d), I-A(k), I-A(S), I-E(d), and I-E(k). In this chapter we show a step-by-step guide into predicting the reliability and the resulting models to represent an advance on existing methods. The peptides used in this study are available from the AntiJen database (http://www.jenner.ac.uk/AntiJen). The PLS method

EDTA modified glassy carbon electrode: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Ustuendag, Zafer [Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Solak, Ali Osman [Ankara University, Faculty of Science, Department of Chemistry, Degol Street, Tandogan, 06100 Ankara (Turkey)], E-mail: osolak@science.ankara.edu.tr

2009-11-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){l_brace}2-[bis(carboxymethyl)amino]-ethyl{r_brace}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb{sup 2+} ions was investigated if this electrode could be used as a metal sensor.

Specification analysis of plutonium fuels for non-metallic impurities. I. Estimation of carbon

Energy Technology Data Exchange (ETDEWEB)

Rizvi, G H; Sethuraman, P R; Venkataramana, P; Natarajan, P R

1975-01-01

An analytical method for the estimation of carbon in plutonium samples in the range of 10-400 ..mu..g by conductometry has been developed. In the first step of the method, the entire carbon in sample is converted into CO/sub 2/ which in the second step is completely absorbed in barium hydroxide solution in conductivity of the solution.

Luminous carbon star in Canis Major OB1

International Nuclear Information System (INIS)

Herbst, W.; Racine, R.; Richer, H.B.

1977-01-01

The fact that W CMa illuminates a reflection nebula is used to argue that it is spatially associated with the CMa OBl/CMa Rl complex. An apparent cluster around the carbon star is found to consist primarly of field stars, although a few probable late B-type members of CMa OBl are identified. On the basis of its likely association with CMa OBl, a luminosity for W CMa is derived. The values M/sub v/ = -4.7 and M/sub bol/ = - 7.2 are found. It seems likely that the progenitor of W CMa was an O-type member of CMa OBl with a mass greater than 20 M/sub solar/ and a main-sequence lifetime less than 3 x 10 6 years

Carbon formation on nickel and nickel-copper alloy catalysts

Energy Technology Data Exchange (ETDEWEB)

Alstrup, I.; Soerensen, O.; Rostrup-Nielsen, J.R. [Haldor Topsoe Research Labs., Lyngby (Denmark); Tavares, M.T.; Bernardo, C.A.

1998-05-01

Equilibrium, kinetic and morphological studies of carbon formation in CH{sub 4} + H{sub 2}, CO, and CO + H{sub 2} gases on silica supported nickel and nickel-copper catalysts are reviewed. The equilibrium deviates in all cases from graphite equilibrium and more so in CO + CO{sub 2} than in CH{sub 4} + H{sub 2}. A kinetic model based on information from surface science results with chemisorption of CH{sub 4} and possibly also the first dehydrogenation step as rate controlling describes carbon formation on nickel catalyst in CH{sub 4} + H{sub 2} well. The kinetics of carbon formation in CO and CO + H{sub 2} gases are in agreement with CO disproportionation as rate determining step. The presence of hydrogen influences strongly the chemisorption of CO. Carbon filaments are formed when hydrogen is present in the gas while encapsulating carbon dominates in pure CO. Small amounts of Cu alloying promotes while larger amounts (Cu : Ni {>=} 0.1) inhibits carbon formation and changes the morphology of the filaments (``octopus`` carbon formation). Adsorption induced nickel segregation changes the kinetics of the alloy catalysts at high carbon activities. Modifications suggested in some very recent papers on the basis of new results are also briefly discussed. (orig.) 31 refs.

Outcome of a 4-step treatment algorithm for depressed inpatients

NARCIS (Netherlands)

Birkenhäger, T.K.; Broek, W.W. van den; Moleman, P.; Bruijn, J.A.

2006-01-01

Objective: The aim of this study was to examine the efficacy and the feasibility of a 4-step treatment algorithm for inpatients with major depressive disorder. Method: Depressed inpatients, meeting DSM-IV criteria for major depressive disorder, were enrolled in the algorithm that consisted of

One-step synthesis of layered CuS/multi-walled carbon nanotube nanocomposites for supercapacitor electrode material with ultrahigh specific capacitance

International Nuclear Information System (INIS)

Huang, Ke-Jing; Zhang, Ji-Zong; Xing, Ke

2014-01-01

In this work, hierarchical-structured copper sulfide/multi-walled carbon nanotubes (CuS/MWCNTs) are synthesized via a one-step hydrothermal process. The chemical composition and microstructure of CuS-MWCNTs are characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and research as electrode matericals for high-performance supercapacitors by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. As expected, the CuS-MWCNTs exhibit a much higher specific capacitance up to 2831 F g −1 , compared with 925.1 F g −1 for CuS and 555.6 F g −1 for MWCNTs. Furthermore, the CuS-MWCNTs hybrids also exhibit good cycling stability with more than 90% capacitance retention over 600 cycles. The enhancement of CuS/MWCNTs in supercapacitor performance not only attribute to their unique 3D structures with large specific surface area, but also their excellent conductivity, which facilitate efficient charge transport and promotes electrolyte diffusion

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

Science.gov (United States)

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

2017-11-01

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

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

Directory of Open Access Journals (Sweden)

M. Schobben

2017-11-01

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

Electrocatalytic reduction of carbon dioxide to carbon monoxide and methane at an immobilized cobalt protoporphyrin

NARCIS (Netherlands)

Shen, J.; Kortlever, R.; Kas, Recep; Mul, Guido; Koper, M.T.M.

2015-01-01

The electrochemical conversion of carbon dioxide and water into useful products is a major challenge in facilitating a closed carbon cycle. Here we report a cobalt protoporphyrin immobilized on a pyrolytic graphite electrode that reduces carbon dioxide in an aqueous acidic solution at relatively low

Biogeochemistry of carbon and related major and trace elements in peat bog soils of the middle taiga of Western Siberia (Russia).

Science.gov (United States)

Stepanova, V. A.; Mironycheva-Tokareva, N. P.; Pokrovsky, O. S.

2012-04-01

Global climate changes impact the status of wetland ecosystems shifting the balances of the carbon, macro-, and microelements cycles. This study aims to establish the features of accumulation and distribution of major- and trace elements in the organic layer of peat bog soils, belonging to different ecosystems of the oligotrophic bog complex located in the middle taiga of Western Siberia (Khanty-Mansiysk region, Russia). Key areas which are selected for this study include the following bog conjugate elementary ecosystems: higher ryam, lower ryam, ridge-hollow complex, and oligotrophic poor fen as characterized previously [1]. We have sampled various peat types along the entire length of the soil column (every 10 cm down to 3 m). Peat samples were analyzed for a wide range of macro- and microelements using an ICP-MS technique following full acid digestion in a microwave oven. These measurements allowed quantitative estimates of major- and trace elements in the peat deposits within the whole bog complex and individual elementary landscapes. Based on the data obtained, the lateral and radial geochemical structures of the bog landscapes were determined and clarified for the first time for middle taiga of the West Siberian plain. The similar regime of mineral nutrition during the complete bog landscape formation was detected for the peat deposits based on the measurements of some major- and trace elements (Ca, Fe, Mg, etc.). The vertical distribution of some major and some trace elements along the profile of peat column is rather uniform with relatively strong increase in the bottom organic layers. This strongly suggests the similarity of the processes of element accumulation in the peat and relatively weak post depositional redistribution of elements within the peat soil profile. Overall, obtained corroborate the existing view on chemical composition of peats being determined by botanical peat's components (which forms this peat deposit), atmospheric precipitation

Carbon changes in conterminous US forests associated with growth and major disturbances: 1992-2001

International Nuclear Information System (INIS)

Zheng Daolan; Ducey, Mark J; Heath, Linda S; Smith, James E

2011-01-01

We estimated forest area and carbon changes in the conterminous United States using a remote sensing based land cover change map, forest fire data from the Monitoring Trends in Burn Severity program, and forest growth and harvest data from the USDA Forest Service, Forest Inventory and Analysis Program. Natural and human-associated disturbances reduced the forest ecosystems' carbon sink by 36% from 1992 to 2001, compared to that without disturbances in the 48 states. Among the three identified disturbances, forest-related land cover change contributed 33% of the total effect in reducing the forest carbon potential sink, while harvests and fires accounted for 63% and 4% of the total effect, respectively. The nation's forests sequestered 1.6 ± 0.1 Pg (10 15 petagram) carbon during the period, or 0.18 Pg C yr -1 , with substantial regional variation. The southern region of the United States was a small net carbon source whereas the greater Pacific Northwest region was a strong net sink. Results of the approach fit reasonably well at an aggregate level with other related estimates of the current forest US greenhouse gas inventory, suggesting that further research using this approach is warranted.

Free Modal Algebras Revisited: The Step-by-Step Method

NARCIS (Netherlands)

Bezhanishvili, N.; Ghilardi, Silvio; Jibladze, Mamuka

2012-01-01

We review the step-by-step method of constructing finitely generated free modal algebras. First we discuss the global step-by-step method, which works well for rank one modal logics. Next we refine the global step-by-step method to obtain the local step-by-step method, which is applicable beyond

SYSTEMATIZATION OF THE BASIC STEPS OF THE STEP-AEROBICS

Directory of Open Access Journals (Sweden)

Darinka Korovljev

2011-03-01

Full Text Available Following the development of the powerful sport industry, in front of us appeared a lot of new opportunities for creating of the new programmes of exercising with certain requisites. One of such programmes is certainly step-aerobics. Step-aerobics can be defined as a type of aerobics consisting of the basic aerobic steps (basic steps applied in exercising on stepper (step bench, with a possibility to regulate its height. Step-aerobics itself can be divided into several groups, depending on the following: type of music, working methods and adopted knowledge of the attendants. In this work, the systematization of the basic steps in step-aerobics was made on the basis of the following criteria: steps origin, number of leg motions in stepping and relating the body support at the end of the step. Systematization of the basic steps of the step-aerobics is quite significant for making a concrete review of the existing basic steps, thus making creation of the step-aerobics lesson easier

Changes in Eocene-Miocene shallow marine carbonate factories along the tropical SE Circum-Caribbean responded to major regional and global environmental and tectonic events

Science.gov (United States)

Silva-Tamayo, Juan Carlos

2015-04-01

Changes in the factory of Cenozoic tropical marine carbonates have been for long attributed to major variations on climatic and environmental conditions. Although important changes on the factories of Cenozoic Caribbean carbonates seem to have followed global climatic and environmental changes, the regional impact of such changes on the factories of shallow marine carbonate along the Caribbean is not well established. Moreover, the influence of transpressional tectonics on the occurrence, distribution and stratigraphy of shallow marine carbonate factories along this area is far from being well understood. Here we report detailed stratigraphic, petrographic and Sr-isotope chemostratigraphic information of several Eocene-Miocene carbonate successions deposited along the equatorial/tropical SE Circum-Caribbean (Colombia and Panama) from which we further assess the influence of changing environmental conditions, transtentional tectonics and sea level change on the development of the shallow marine carbonate factories. Our results suggest that during the Eocene-early Oligocene interval, a period of predominant high atmospheric pCO2, coralline algae constitute the principal carbonate builders of shallow marine carbonate successions along the SE Circum-Caribbean. Detailed stratigraphic and paragenetic analyses suggest the developed of laterally continuous red algae calcareous build-ups along outer-rimmed carbonate platforms. The predominance of coralline red algae over corals on the shallow marine carbonate factories was likely related to high sea surface temperatures and high turbidity. The occurrence of such build-ups was likely controlled by pronounce changes in the basin paleotopography, i.e. the occurrence of basement highs and lows, resulting from local transpressional tectonics. The occurrence of these calcareous red algae dominated factories was also controlled by diachronic opening of different sedimentary basins along the SE Circum Caribbean resulting from

Effect of the processing steps on compositions of table olive since harvesting time to pasteurization.

Science.gov (United States)

Nikzad, Nasim; Sahari, Mohammad A; Vanak, Zahra Piravi; Safafar, Hamed; Boland-nazar, Seyed A

2013-08-01

Weight, oil, fatty acids, tocopherol, polyphenol, and sterol properties of 5 olive cultivars (Zard, Fishomi, Ascolana, Amigdalolia, and Conservalia) during crude, lye treatment, washing, fermentation, and pasteurization steps were studied. Results showed: oil percent was higher and lower in Ascolana (crude step) and in Fishomi (pasteurization step), respectively; during processing steps, in all cultivars, oleic, palmitic, linoleic, and stearic acids were higher; the highest changes in saturated and unsaturated fatty acids were in fermentation step; the highest and the lowest ratios of ω3 / ω6 were in Ascolana (washing step) and in Zard (pasteurization step), respectively; the highest and the lowest tocopherol were in Amigdalolia and Fishomi, respectively, and major damage occurred in lye step; the highest and the lowest polyphenols were in Ascolana (crude step) and in Zard and Ascolana (pasteurization step), respectively; the major damage among cultivars occurred during lye step, in which the polyphenol reduced to 1/10 of first content; sterol did not undergo changes during steps. Reviewing of olive patents shows that many compositions of fruits such as oil quality, fatty acids, quantity and its fraction can be changed by alteration in cultivar and process.

Specification analysis of plutonium fuels for non-metallic impurities. I - estimation of carbon

International Nuclear Information System (INIS)

Rizvi, G.H.; Sethuraman, P.R.; Venkataramana, P.; Natarajan, P.R.

1975-01-01

An analytical method for the estimation of carbon in plutonium samples in the range of 10-400 μg by conductometry has been developed. In the first step of the method, the entire carbon in sample is converted into CO 2 which in the second step is completely absorbed in barium hydroxide solution in conductivity of the solution. (M.G.B.)

Growth and demise of a Paleogene isolated carbonate platform of the Offshore Indus Basin, Pakistan: effects of regional and local controlling factors

Science.gov (United States)

Shahzad, Khurram; Betzler, Christian; Ahmed, Nadeem; Qayyum, Farrukh; Spezzaferri, Silvia; Qadir, Anwar

2018-03-01

Based on high-resolution seismic and well datasets, this paper examines the evolution and drowning history of a Paleocene-Eocene carbonate platform in the Offshore Indus Basin of Pakistan. This study uses the internal seismic architecture, well log data as well as the microfauna to reconstruct factors that governed the carbonate platform growth and demise. Carbonates dominated by larger benthic foraminifera assemblages permit constraining the ages of the major evolutionary steps and show that the depositional environment was tropical within oligotrophic conditions. With the aid of seismic stratigraphy, the carbonate platform edifice is resolved into seven seismic units which in turn are grouped into three packages that reflect its evolution from platform initiation, aggradation with escarpment formation and platform drowning. The carbonate factory initiated as mounds and patches on a Cretaceous-Paleocene volcanic complex. Further, the growth history of the platform includes distinct phases of intraplatform progradation, aggradation, backstepping and partial drownings. The youngest succession as late-stage buildup records a shift from benthic to pelagic deposition and marks the final drowning in the Early Eocene. The depositional trend of the platform, controlled by the continuing thermal subsidence associated with the cooling of volcanic margin lithosphere, was the major contributor of the accommodation space which supported the vertical accumulation of shallow water carbonate succession. Other factors such as eustatic changes and changes in the carbonate producers as a response to the Paleogene climatic perturbations played secondary roles in the development and drowning of these buildups.

Assessing and Synthesizing the Last Decade of Research on the Major Pools and Fluxes of the Carbon Cycle in the US and North America: An Interagency Governmental Perspective

Science.gov (United States)

Cavallaro, N.; Shrestha, G.; Stover, D. B.; Zhu, Z.; Ombres, E. H.; Deangelo, B.

2015-12-01

The 2nd State of the Carbon Cycle Report (SOCCR-2) is focused on US and North American carbon stocks and fluxes in managed and unmanaged systems, including relevant carbon management science perspectives and tools for supporting and informing decisions. SOCCR-2 is inspired by the US Carbon Cycle Science Plan (2011) which emphasizes global scale research on long-lived, carbon-based greenhouse gases, carbon dioxide and methane, and the major pools and fluxes of the global carbon cycle. Accordingly, the questions framing the Plan inform this report's topical roadmap, with a focus on US and North America in the global context: 1) How have natural processes and human actions affected the global carbon cycle on land, in the atmosphere, in the oceans and in the ecosystem interfaces (e.g. coastal, wetlands, urban-rural)? 2) How have socio-economic trends affected the levels of the primary carbon-containing gases, carbon dioxide and methane, in the atmosphere? 3) How have species, ecosystems, natural resources and human systems been impacted by increasing greenhouse gas concentrations, the associated changes in climate, and by carbon management decisions and practices? To address these aspects, SOCCR-2 will encompass the following broad assessment framework: 1) Carbon Cycle at Scales (Global Perspective, North American Perspective, US Perspective, Regional Perspective); 2) Role of carbon in systems (Soils; Water, Oceans, Vegetation; Terrestrial-aquatic Interfaces); 3) Interactions/Disturbance/Impacts from/on the carbon cycle. 4) Carbon Management Science Perspective and Decision Support (measurements, observations and monitoring for research and policy relevant decision-support etc.). In this presentation, the Carbon Cycle Interagency Working Group and the U.S. Global Change Research Program's U.S. Carbon Cycle Science Program Office will highlight the scientific context, strategy, structure, team and production process of the report, which is part of the USGCRP's Sustained

One Step Hydrogen Generation Through Sorption Enhanced Reforming

Energy Technology Data Exchange (ETDEWEB)

Mays, Jeff [Gas Technology Inst., Des Plaines, IL (United States)

2017-08-03

One-step hydrogen generation, using Sorption Enhanced Reforming (SER) technology, is an innovative means of providing critical energy and environmental improvements to US manufacturing processes. The Gas Technology Institute (GTI) is developing a Compact Hydrogen Generator (CHG) process, based on SER technology, which successfully integrates previously independent process steps, achieves superior energy efficiency by lowering reaction temperatures, and provides pathways to doubling energy productivity with less environmental pollution. GTI’s prior CHG process development efforts have culminated in an operational pilot plant. During the initial pilot testing, GTI identified two operating risks- 1) catalyst coating with calcium aluminate compounds, 2) limited solids handling of the sorbent. Under this contract GTI evaluated alternative materials (one catalyst and two sorbents) to mitigate both risks. The alternate catalyst met performance targets and did not experience coating with calcium aluminate compounds of any kind. The alternate sorbent materials demonstrated viable operation, with one material enabling a three-fold increase in sorbent flow. The testing also demonstrated operation at 90% of its rated capacity. Lastly, a carbon dioxide co-production study was performed to assess the advantage of the solid phase separation of carbon dioxide- inherent in the CHG process. Approximately 70% lower capital cost is achievable compared to SMR-based hydrogen production with CO2 capture, as well as improved operating costs.

Method for making carbon super capacitor electrode materials

Science.gov (United States)

Firsich, David W.; Ingersoll, David; Delnick, Frank M.

1998-01-01

A method for making near-net-shape, monolithic carbon electrodes for energy storage devices. The method includes the controlled pyrolysis and activation of a pressed shape of methyl cellulose powder with pyrolysis being carried out in two stages; pre-oxidation, preferably in air at a temperature between 200.degree.-250.degree. C., followed by carbonization under an inert atmosphere. An activation step to adjust the surface area of the carbon shape to a value desirable for the application being considered, including heating the carbon shape in an oxidizing atmosphere to a temperature of at least 300.degree. C., follows carbonization.

Investigating the Conceptual Variation of Major Physics Textbooks

Science.gov (United States)

Stewart, John; Campbell, Richard; Clanton, Jessica

2008-04-01

The conceptual problem content of the electricity and magnetism chapters of seven major physics textbooks was investigated. The textbooks presented a total of 1600 conceptual electricity and magnetism problems. The solution to each problem was decomposed into its fundamental reasoning steps. These fundamental steps are, then, used to quantify the distribution of conceptual content among the set of topics common to the texts. The variation of the distribution of conceptual coverage within each text is studied. The variation between the major groupings of the textbooks (conceptual, algebra-based, and calculus-based) is also studied. A measure of the conceptual complexity of the problems in each text is presented.

2-Step IMAT and 2-Step IMRT in three dimensions

International Nuclear Information System (INIS)

Bratengeier, Klaus

2005-01-01

the additional segment as well as the integral across the segment profile was demonstrated to be an important value. This product was up to a factor of 3 larger than in the 2-D case. Even in three dimensions, the optimized 2-Step IMAT increased the homogeneity of the dose distribution in the PTV profoundly. Rules for adaptation to varying target-OAR combinations were deduced. It can be concluded that 2-Step IMAT and 2-Step IMRT are also applicable in three dimensions. In the majority of cases, weights between 0.5 and 2 will occur for the additional segment. The width-weight product of the second segment is always smaller than the normalized radius of the OAR. The width-weight product of the additional segment is strictly connected to the relevant diameter of the organ at risk and the target volume. The derived formulas can be helpful to adapt an IMRT plan to altering target shapes

Carbon Management In the Post-Cap-and-Trade Carbon Economy

Science.gov (United States)

DeGroff, F. A.

2013-12-01

This abstract outlines an economic model that integrates carbon externalities seamlessly into the national and international economies. The model incorporates a broad carbon metric used to value all carbon in the biosphere, as well as all transnational commerce. The model minimizes the cost associated with carbon management, and allows for the variation in carbon avidity between jurisdictions. When implemented over time, the model reduces the deadweight loss while minimizing social cost, thus maximizing the marginal social benefit commonly associated with Pigouvian taxes. Once implemented, the model provides a comprehensive economic construct for governments, industry and consumers to efficiently weigh the cost of carbon, and effectively participate in helping to reduce their direct and indirect use of carbon, while allowing individual jurisdictions to decide their own carbon value, without the need for explicit, express agreement of all countries. The model uses no credits, requires no caps, and matches climate changing behavior to costs. The steps to implement the model for a particular jurisdiction are: 1) Define the Carbon Metric to value changes in Carbon Quality. 2) Apply the Carbon Metric to assess the Carbon Toll a) for all changes in Carbon Quality and b) for imports and exports. This economic model has 3 clear advantages. 1) The carbon pricing and cost scheme use existing and generally accepted accounting methodologies to ensure the veracity and verifiability of carbon management efforts with minimal effort and expense using standard auditing protocols. Implementing this economic model will not require any special training, tools, or systems for any entity to achieve their minimum carbon target goals within their jurisdictional framework. 2) Given the spectrum of carbon affinities worldwide, the model recognizes and provides for flexible carbon pricing regimes, but does not penalize domestic carbon-consuming producers subject to imports from exporters in

Approved parallel methods for characterisation of solid carbon

International Nuclear Information System (INIS)

Fitzer, E.

1976-01-01

The contribution gives instructions for the work routine for 1) qualitative radiographic characterization of the microstructural order of solid carbon specimens, 2) X-ray determination of the mean interlattice plane distance anti c/2 of carbons, 3) determination of the helium density of carbons by means of the reference pycnometer, 4) determination of the specific surface area of carbon samples from nitrogen absorption. These instructions for the characterization of solid carbons are the first step towards a collection and comparison of the methods used in the participating countries. The international carbon groups (carbon societies) plan to supplement this collection for every international carbon conference. This collection will serve as a basis for the establishment of international working instructions. (orig./IHOE) [de

Poly(urethane–carbonate)s from Carbon Dioxide

KAUST Repository

Chen, Zuliang; Hadjichristidis, Nikolaos; Feng, Xiaoshuang; Gnanou, Yves

2017-01-01

A one-pot, two-step protocol for the direct synthesis of polyurethanes containing few carbonate linkages through polycondensation of diamines, dihalides, and CO2 in the presence of Cs2CO3 and tetrabutylammonium bromide is described. The conditions were optimized by studying the polycondensation of CO2 with 1,6-hexanediamine and 1,4-dibromobutane as model monomers. Then, various diamines and dihalides were tested under optimal conditions. Miscellaneous samples of such carbonate-containing polyurethanes exhibiting molar masses from 6000 to 22 000 g/mol (GPC) and yields higher than 85% were obtained. The thermal properties of such polyurethanes were unveiled by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA): they were found very similar to those of traditional polyurethanes obtained by diisocyanates + diols polycondensation.

Poly(urethane–carbonate)s from Carbon Dioxide

KAUST Repository

Chen, Zuliang

2017-03-09

A one-pot, two-step protocol for the direct synthesis of polyurethanes containing few carbonate linkages through polycondensation of diamines, dihalides, and CO2 in the presence of Cs2CO3 and tetrabutylammonium bromide is described. The conditions were optimized by studying the polycondensation of CO2 with 1,6-hexanediamine and 1,4-dibromobutane as model monomers. Then, various diamines and dihalides were tested under optimal conditions. Miscellaneous samples of such carbonate-containing polyurethanes exhibiting molar masses from 6000 to 22 000 g/mol (GPC) and yields higher than 85% were obtained. The thermal properties of such polyurethanes were unveiled by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA): they were found very similar to those of traditional polyurethanes obtained by diisocyanates + diols polycondensation.

Method for nano-pumping using carbon nanotubes

Science.gov (United States)

Insepov, Zeke [Darien, IL; Hassanein, Ahmed [Bolingbrook, IL

2009-12-15

The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

Carbon/ λ-MnO 2 composites for supercapacitor electrodes

Science.gov (United States)

Malak-Polaczyk, A.; Matei-Ghimbeu, C.; Vix-Guterl, C.; Frackowiak, E.

2010-04-01

In the present work a composite of carbon with λ-MnO 2 have been synthesized by a simple two-step route. In the first step, to obtain LiMn 2O 4/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of λ-MnO 2/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed λ-MnO 2 particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the λ-MnO 2 is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation.

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

International Nuclear Information System (INIS)

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

2013-01-01

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

Controllable 3D architectures of aligned carbon nanotube arrays by multi-step processes

Science.gov (United States)

Huang, Shaoming

2003-06-01

An effective way to fabricate large area three-dimensional (3D) aligned CNTs pattern based on pyrolysis of iron(II) phthalocyanine (FePc) by two-step processes is reported. The controllable generation of different lengths and selective growth of the aligned CNT arrays on metal-patterned (e.g., Ag and Au) substrate are the bases for generating such 3D aligned CNTs architectures. By controlling experimental conditions 3D aligned CNT arrays with different lengths/densities and morphologies/structures as well as multi-layered architectures can be fabricated in large scale by multi-step pyrolysis of FePc. These 3D architectures could have interesting properties and be applied for developing novel nanotube-based devices.

Sculpting carbon bonds for allotropic transformation through solid-state re-engineering of –sp2 carbon

Energy Technology Data Exchange (ETDEWEB)

Jung, Hyun Young; Araujo, Paulo T.; Kim, Young Lae; Jung, Sung Mi; Jia, Xiaoting; Hong, Sanghyun; Ahn, Chi Won; Kong, Jing; Dresselhaus, Mildred S.; Kar, Swastik; Jung, Yung Joon

2014-09-15

Carbon forms one of nature’s strongest chemical bonds; its allotropes having provided some of the most exciting scientific discoveries in recent times. The possibility of inter-allotropic transformations/hybridization of carbon is hence a topic of immense fundamental and technological interest. Such modifications usually require extreme conditions (high temperature, pressure and/or high-energy irradiations), and are usually not well controlled. Here we demonstrate inter-allotropic transformations/hybridizations of specific types that appear uniformly across large-area carbon networks, using moderate alternating voltage pulses. By controlling the pulse magnitude, small-diameter single-walled carbon nanotubes can be transformed predominantly into larger-diameter single-walled carbon nanotubes, multi-walled carbon nanotubes of different morphologies, multi-layered graphene nanoribbons or structures with sp3 bonds. This re-engineering of carbon bonds evolves via a coalescence-induced reconfiguration of sp2 hybridization, terminates with negligible introduction of defects and demonstrates remarkable reproducibility. This reflects a potential step forward for large-scale engineering of nanocarbon allotropes and their junctions.

Activated carbon from biomass

Science.gov (United States)

Manocha, S.; Manocha, L. M.; Joshi, Parth; Patel, Bhavesh; Dangi, Gaurav; Verma, Narendra

2013-06-01

Activated carbon are unique and versatile adsorbents having extended surface area, micro porous structure, universal adsorption effect, high adsorption capacity and high degree of surface reactivity. Activated carbons are synthesized from variety of materials. Most commonly used on a commercial scale are cellulosic based precursors such as peat, coal, lignite wood and coconut shell. Variation occurs in precursors in terms of structure and carbon content. Coir having very low bulk density and porous structure is found to be one of the valuable raw materials for the production of highly porous activated carbon and other important factor is its high carbon content. Exploration of good low cost and non conventional adsorbent may contribute to the sustainability of the environment and offer promising benefits for the commercial purpose in future. Carbonization of biomass was carried out in a horizontal muffle furnace. Both carbonization and activation were performed in inert nitrogen atmosphere in one step to enhance the surface area and to develop interconnecting porosity. The types of biomass as well as the activation conditions determine the properties and the yield of activated carbon. Activated carbon produced from biomass is cost effective as it is easily available as a waste biomass. Activated carbon produced by combination of chemical and physical activation has higher surface area of 2442 m2/gm compared to that produced by physical activation (1365 m2/gm).

Isotopic fractionation between organic carbon and carbonate carbon in Precambrian banded ironstone series from Brazil

International Nuclear Information System (INIS)

Schidlowski, M.; Eichmann, R.; Fiebiger, W.

1976-01-01

37 delta 13 Csub(org) and 9 delta 13 Csub(carb) values furnished by argillaceous and carbonate sediments from the Rio das Velhas and Minas Series (Minas Gerais, Brazil) have yielded means of -24.3 +- 3.9 promille [PDB] and -0.9 +- 1.4 promille [PDB], respectively. These results, obtained from a major sedimentary banded ironstone province with an age between 2 and 3 x 10 9 yr, support previous assumptions that isotopic fractionation between inorganic and organic carbon in Precambrian sediments is about the same as in Phanerozoic rocks. This is consistent with a theoretically expected constancy of the kinetic fractionation factor governing biological carbon fixation and, likewise, with a photosynthetic pedigree of the reduced carbon fraction of Precambrian rocks. (orig.) [de

Reactive extraction of carboxylic acids from apolar hydrocarbons using aqueous solutions of sodium hydrogen carbonate with back-recovery using carbon dioxide under pressure

NARCIS (Netherlands)

Kuzmanovic, B.; Kuipers, N.J.M.; de Haan, A.B.; Kwant, Gerard

2005-01-01

A combination of using an aqueous solution of sodium hydrogen carbonate for forward-extraction of carboxylic acids from a dilute apolar organic solvent, and carbon dioxide under pressure for its back-recovery, is studied. Used in combination, these two steps might provide a technique for the

Indirect Climatic Effects of Major Volcanic Eruptions

Science.gov (United States)

Hofmann, D. J.

2007-05-01

The direct effects on climate, related to atmospheric emissions to the atmosphere following major volcanic eruptions, are well-known although the sparseness of such eruptions make detailed study on the range of such variations difficult. In general terms, infrared absorption by volcanic emissions to the stratosphere result in local heating early in the event when gaseous sulfur compounds exist. This early period is followed by gas to particle conversion, on a time scale of 1-2 months, promoting the formation of sulfuric acid-water droplets. Coagulation and droplet growth result in the "volcanic stratospheric aerosol layer" which is related to the predominant direct climatic effect of large eruptions, the cooling of the troposphere by backscattering of solar visible radiation to space with a recovery time scale of 1-2 years. In this paper we will discuss some of the less-known "indirect" effects of the volcanic stratospheric aerosol on climate. We label them indirect as they act on climate through intermediary atmospheric constituents. The intermediaries in the volcanic indirect climatic effect are generally atmospheric greenhouse gases or other atmospheric gases and conditions which affect greenhouse gases. For example, cooling of the troposphere following major eruptions reduces the growth rate of atmospheric carbon dioxide related to respiration by the terrestrial biosphere. In addition, redirection of part of the direct solar beam into diffuse radiation by the volcanic stratospheric aerosol stimulates plant photosynthesis, further reducing the carbon dioxide growth rate. The growth rate of the second-most important atmospheric greenhouse gas, methane, is also affected by volcanic emissions. Volcanic stratospheric aerosol particles provide surface area which catalyzes heterogeneous chemical reactions thus stimulating removal of stratospheric ozone, also a greenhouse gas. Although major droughts usually related to ENSO events have opposite effects on carbon

Human-accelerated weathering increases salinization, major ions, and alkalinization in fresh water across land use

Science.gov (United States)

Human land use increases transport of dissolved inorganic carbon and major ions in watersheds due to the combination of easily weathered materials in watersheds and anthropogenic inputs. Here, we show that dissolved inorganic carbon (DIC), alkalinity, and major ions are significa...

Carbon Budget and its Dynamics over Northern Eurasia Forest Ecosystems

Science.gov (United States)

Shvidenko, Anatoly; Schepaschenko, Dmitry; Kraxner, Florian; Maksyutov, Shamil

2016-04-01

The presentation contains an overview of recent findings and results of assessment of carbon cycling of forest ecosystems of Northern Eurasia. From a methodological point of view, there is a clear tendency in understanding a need of a Full and Verified Carbon Account (FCA), i.e. in reliable assessment of uncertainties for all modules and all stages of FCA. FCA is considered as a fuzzy (underspecified) system that supposes a system integration of major methods of carbon cycling study (land-ecosystem approach, LEA; process-based models; eddy covariance; and inverse modelling). Landscape-ecosystem approach 1) serves for accumulation of all relevant knowledge of landscape and ecosystems; 2) for strict systems designing the account, 3) contains all relevant spatially distributed empirical and semi-empirical data and models, and 4) is presented in form of an Integrated Land Information System (ILIS). The ILIS includes a hybrid land cover in a spatially and temporarily explicit way and corresponding attributive databases. The forest mask is provided by utilizing multi-sensor remote sensing data, geographically weighed regression and validation within GEO-wiki platform. By-pixel parametrization of forest cover is based on a special optimization algorithms using all available knowledge and information sources (data of forest inventory and different surveys, observations in situ, official statistics of forest management etc.). Major carbon fluxes within the LEA (NPP, HR, disturbances etc.) are estimated based on fusion of empirical data and aggregations with process-based elements by sets of regionally distributed models. Uncertainties within LEA are assessed for each module and at each step of the account. Within method results of LEA and corresponding uncertainties are harmonized and mutually constrained with independent outputs received by other methods based on the Bayesian approach. The above methodology have been applied to carbon account of Russian forests for 2000

Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

DEFF Research Database (Denmark)

Kindler, Reimo; Siemens, Jan; Kaiser, Klaus

2011-01-01

ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24–105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small...... solubility of CO2 in acidic forest soil solutions and large NEE. Leaching of CH4 proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems....

Sodium-carbonate co-substituted hydroxyapatite ceramics

Directory of Open Access Journals (Sweden)

Zoltan Z. Zyman

2013-12-01

Full Text Available Powders of sodium-carbonate co-substituted hydroxyapatite, having sodium content in the range of 0.25–1.5 wt.% with a 0.25 wt.% step, were prepared by a precipitation-solid state reaction route. Compacts of the powders were sintered in a CO2 flow (4 mL/min at 1100 °C for 2 h. The sintered ceramics contained sodium and carbonate ions in the ranges of 0–1.5 wt.% and 1.3–6 wt.%, respectively, which are typical impurity concentrations in biological apatite. A relationship between sodium and carbonate contents and the type of carbonate substitution was found. The total carbonate content progressively increased with the sodium content. The obtained ceramics showed an AB-type carbonate substitution. However, the substitution became more B-type as the sodium content increased. As a result, the carbonation was almost B-type (94 % for the highest sodium content (1.5 wt.%.

Variation in carbon stocks on different slope aspects in seven major forest types of temperate region of Garhwal Himalaya, India.

Science.gov (United States)

Sharma, C M; Gairola, Sumeet; Baduni, N P; Ghildiyal, S K; Suyal, Sarvesh

2011-09-01

The present study was undertaken in seven major forest types of temperate zone (1500 m a.s.l. to 3100 m a.s.l.) of Garhwal Himalaya to understand the effect of slope aspects on carbon (C) density and make recommendations for forest management based on priorities for C conservation/sequestration. We assessed soil organic carbon (SOC) density, tree density, biomass and soil organic carbon (SOC) on four aspects, viz. north/east (NE), north/west (NW), south-east (SE) and south-west (SW), in forest stands dominated by Abies pindrow, Cedrus deodara, Pinus roxburghii, Cupressus torulosa, Quercus floribunda, Quercus semecarpifolia and Quercus leucotrichophora. TCD ranged between 77.3 CMg ha⁻¹ on SE aspect (Quercus leucotrichophora forest) and 291.6 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). SOC varied between 40.3 CMg ha⁻¹ on SW aspect (Himalayan Pinus roxburghii forest) and 177.5 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). Total C density (SOC+TCD) ranged between 118.1 CMg ha⁻¹ on SW aspect (Himalayan Pinus roxburghii forest) and 469.1 CMg ha⁻¹ on NE aspect (moist Cedrus deodara forest). SOC and TCD were significantly higher on northern aspects as compared with southern aspects. It is recommended that for C sequestration, the plantation silviculture be exercised on northern aspects, and for C conservation purposes, mature forest stands growing on northern aspects be given priority.

Normal Range of Head-to-body Delivery Interval by Two-step Delivery

Directory of Open Access Journals (Sweden)

Hong-Yu Zhang

2016-01-01

Conclusions: The average time of head-to-body delivery interval was longer than 60 s by two-step delivery. Majority shoulders were delivered at the first contraction. Majority shoulders emerged from perineum rather from under pubic arch. The routine one-step method of shoulder delivery where the downward force applied is not necessary and is not the right direction. Baby's breath, making faces, sucking, bubble from noses and mouth, and the light blue color of the faces, all those signs during shoulder delivery indicated a normal live birth.

A rapid and efficient two-step gel electrophoresis method for the purification of major rye grass pollen allergens.

Science.gov (United States)

Levy, D; Davies, J; O'Hehir, R; Suphioglu, C

2001-06-01

Purified proteins are mandatory for molecular, immunological and cellular studies. However, purification of proteins from complex mixtures requires specialised chromatography methods (i.e., gel filtration, ion exchange, etc.) using fast protein liquid chromatography (FPLC) or high-performance liquid chromatography (HPLC) systems. Such systems are expensive and certain proteins require two or more different steps for sufficient purity and generally result in low recovery. The aim of this study was to develop a rapid, inexpensive and efficient gel-electrophoresis-based protein purification method using basic and readily available laboratory equipment. We have used crude rye grass pollen extract to purify the major allergens Lol p 1 and Lol p 5 as the model protein candidates. Total proteins were resolved on large primary gel and Coomassie Brilliant Blue (CBB)-stained Lol p 1/5 allergens were excised and purified on a secondary "mini"-gel. Purified proteins were extracted from unstained separating gels and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot analyses. Silver-stained SDS-PAGE gels resolved pure proteins (i.e., 875 microg of Lol p 1 recovered from a 8 mg crude starting material) while immunoblot analysis confirmed immunological reactivity of the purified proteins. Such a purification method is rapid, inexpensive, and efficient in generating proteins of sufficient purity for use in monoclonal antibody (mAb) production, protein sequencing and general molecular, immunological, and cellular studies.

Efficient Electrocatalytic Reduction of CO2 by Nitrogen-Doped Nanoporous Carbon/Carbon Nanotube Membranes - A Step Towards the Electrochemical CO2 Refinery

KAUST Repository

Wang, Hong; Jia, Jia; Song, Pengfei; Wang, Qiang; Li, Debao; Min, Shixiong; Qian, Chenxi; Wang, Lu; Li, Young Feng; Ma, Chun; Wu, Tao; Yuan, Jiayin; Antonietti, Markus; Ozin, Geoffrey A.

2017-01-01

The search for earth abundant, efficient and stable electrocatalysts that can enable the chemical reduction of CO2 to value-added chemicals and fuels at an industrially relevant scale, is a high priority for the development of a global network of renewable energy conversion and storage systems that can meaningfully impact greenhouse gas induced climate change. Here we introduce a straightforward, low cost, scalable and technologically relevant method to manufacture an all-carbon, electroactive, nitrogen-doped nanoporous carbon-carbon nanotube composite membrane. The membrane is demonstrated to function as a binder-free, high-performance electrode for the electrocatalytic reduction of CO2 to formate. The Faradaic efficiency for the production of formate is 81%. Furthermore, the robust structural and electrochemical properties of the membrane endow it with excellent long-term stability.

Efficient Electrocatalytic Reduction of CO2 by Nitrogen-Doped Nanoporous Carbon/Carbon Nanotube Membranes - A Step Towards the Electrochemical CO2 Refinery

KAUST Repository

Wang, Hong

2017-05-12

The search for earth abundant, efficient and stable electrocatalysts that can enable the chemical reduction of CO2 to value-added chemicals and fuels at an industrially relevant scale, is a high priority for the development of a global network of renewable energy conversion and storage systems that can meaningfully impact greenhouse gas induced climate change. Here we introduce a straightforward, low cost, scalable and technologically relevant method to manufacture an all-carbon, electroactive, nitrogen-doped nanoporous carbon-carbon nanotube composite membrane. The membrane is demonstrated to function as a binder-free, high-performance electrode for the electrocatalytic reduction of CO2 to formate. The Faradaic efficiency for the production of formate is 81%. Furthermore, the robust structural and electrochemical properties of the membrane endow it with excellent long-term stability.

Iron filled carbon nanostructures from different precursors

International Nuclear Information System (INIS)

Costa, S.; Borowiak-Palen, E.; Bachmatiuk, A.; Ruemmeli, M.H.; Gemming, T.; Kalenczuk, R.J.

2008-01-01

Here, we present a study on the synthesis of different nanostructures with one single-step in situ filling (encapsulation) via carbon vapor deposition (CVD). Ferrocene, acetylferrocene and iron (II) nitrate as iron precursors were explored. The application of each of these compounds resulted in different carbon nanomaterials such as: iron filled multiwalled carbon nanotubes with a low filling ratio (Fe-MWCNT), iron filled nanocapsules and unfilled MWCNT. The as-produced samples were purified by high temperature annealing and acid treatment. The purified materials were characterised using transmission electron microscopy (TEM) and Raman spectroscopy

Carbon fiber reinforcements for sheet molding composites

Science.gov (United States)

Ozcan, Soydan; Paulauskas, Felix L.

2017-11-14

A method of processing a carbon fiber tow includes the steps of providing a carbon fiber tow made of a plurality of carbon filaments, depositing a sizing composition at spaced-apart sizing sites along a length of the tow, leaving unsized interstitial regions of the tow, and cross-cutting the tow into a plurality of segments. Each segment includes at least a portion of one of the sizing sites and at least a portion of at least one of the unsized regions of the tow, the unsized region including and end portion of the segment.

An Experiment on the Carbonization of Fuel Compact Matrix Graphite for HTGR

International Nuclear Information System (INIS)

Lee, Young Woo; Kim, Joo Hyoung; Cho, Moon Sung

2012-01-01

The fuel element for HTGR is manufactured by mixing coated fuel particles with matrix graphite powder and forming into either pebble type or cylindrical type compacts depending on their use in different HTGR cores. The coated fuel particle, the so-called TRISO particle, consists of 500-μm spherical UO 2 particles coated with the low density buffer Pyrolytic Carbon (PyC) layer, the inner and outer high density PyC layer and SiC layer sandwiched between the two inner and outer PyC layers. The coated TRISO particles are mixed with a properly prepared matrix graphite powder, pressed into a spherical shape or a cylindrical compact, and finally heat-treated at about 1800 .deg. C. These fuel elements can have different sizes and forms of compact. The basic steps for manufacturing a fuel element include preparation of graphite matrix powder, over coating the fuel particles, mixing the fuel particles with a matrix powder, carbonizing green compact, and the final high-temperature heat treatment of the carbonized fuel compact. The carbonization is a process step where the binder that is incorporated during the matrix graphite powder preparation step is evaporated and the residue of the binder is carbonized during the heat treatment at about 1073 K, In order to develop a fuel compact fabrication technology, and for fuel matrix graphite to meet the required material properties, it is of extreme importance to investigate the relationship among the process parameters of the matrix graphite powder preparation, fabrication parameters of fuel element green compact and the carbonization condition, which has a strong influence on further steps and the material properties of fuel element. In this work, the carbonization behavior of green compact samples prepared from the matrix graphite powder mixtures with different binder materials was investigated in order to elucidate the behavior of binders during the carbonization heat treatment by analyzing the change in weight, density and its

Catalytic Growth of Macroscopic Carbon Nanofibers Bodies with Activated Carbon

Science.gov (United States)

Abdullah, N.; Rinaldi, A.; Muhammad, I. S.; Hamid, S. B. Abd.; Su, D. S.; Schlogl, R.

2009-06-01

Carbon-carbon composite of activated carbon and carbon nanofibers have been synthesized by growing Carbon nanofiber (CNF) on Palm shell-based Activated carbon (AC) with Ni catalyst. The composites are in an agglomerated shape due to the entanglement of the defective CNF between the AC particles forming a macroscopic body. The macroscopic size will allow the composite to be used as a stabile catalyst support and liquid adsorbent. The preparation of CNT/AC nanocarbon was initiated by pre-treating the activated carbon with nitric acid, followed by impregnation of 1 wt% loading of nickel (II) nitrate solutions in acetone. The catalyst precursor was calcined and reduced at 300° C for an hour in each step. The catalytic growth of nanocarbon in C2H4/H2 was carried out at temperature of 550° C for 2 hrs with different rotating angle in the fluidization system. SEM and N2 isotherms show the level of agglomeration which is a function of growth density and fluidization of the system. The effect of fluidization by rotating the reactor during growth with different speed give a significant impact on the agglomeration of the final CNF/AC composite and thus the amount of CNFs produced. The macrostructure body produced in this work of CNF/AC composite will have advantages in the adsorbent and catalyst support application, due to the mechanical and chemical properties of the material.

Carbon capture and storage: steering between necessity and realism

International Nuclear Information System (INIS)

Finon, D.; Damian, M.

2011-01-01

Carbon sequestration is the option that will make possible to keep fossil energies in the future energy mix. This technology could be used for fixed carbon emission sources like fossil power plants or oil refineries or steel works or cement factories. Today 3 technologies to capture carbon have to be considered: post-combustion, pre-combustion and oxy-combustion, these technologies are expected to be used equally. The second step is the construction of a network of gas pipelines to transport CO 2 to the storage place. The last step is the storage that can be done in ancient oil or natural gas fields or in deep coal layers on in deep salt aquifer. The latter being the most promising. With a carbon emission price comprised between 30 and 50 euros a tonne, carbon sequestration is expected to be economically competitive around 2030 under the condition that the feedback experience gained from the first industrial installations on a large scale have made investment costs drop sharply. Because of its need for important initial investment carbon sequestration appears to be as capitalistic as nuclear energy and will require public funding. Demonstration programs have been launched in Europe, United-States, Canada and Australia. (A.C.)

Structural evolution of Eucalyptus tar pitch-based carbons during carbonization

International Nuclear Information System (INIS)

Prauchner, Marcos J.; Pasa, Vanya M.D.; Molhallem, Nelcy D.S.; Otani, Choyu; Otani, Satika; Pardini, Luiz C.

2005-01-01

Wood tar pitches are generated as by-products by the charcoal manufacturing industry. They have a macromolecular structure constituted mainly by phenolic, guaiacylic, and siringylic units common to lignin. Due to their characteristics, biopitches are been investigated as precursors of carbon materials such as carbon fibers, bioelectrodes and activated carbons. In the present work the structural evolution of Eucalyptus tar pitches under carbonization is investigated, which is important for the improvement of planning and control of pitch processing and end-product properties during carbon material production. The studies involve X-ray diffraction and infrared analyses, besides helium density, BET surface area and BJH pore volume measurements. The results showed that the conversion of pitch into carbon basically involves three steps: (1) Up to around 600 deg C the material has an highly disordered structure, being the release of aliphatic side chains and volatiles the main events taking place. (2) Between 600 deg C and 800 deg C, condensation of aromatic rings occurs to form bi-dimensional hexagonal networks so that micro- and mesoporosity are developed. The 800 deg C-coke is constituted by two phases: one highly disordered and another more crystalline. (3) Over 800 deg C, both phases are gradually ordered. As defects are gradually removed, surface area and porosity decrease, approaching zero for the 2100 deg C-coke

The step complexity measure for emergency operating procedures: measure verification

International Nuclear Information System (INIS)

Park, Jinkyun; Jung, Wondea; Ha, Jaejoo; Park, Changkue

2002-01-01

In complex systems, such as nuclear power plants (NPPs) or airplane control systems, human errors play a major role in many accidents. Therefore, to prevent an occurrence of accidents or to ensure system safety, extensive effort has been made to identify significant factors that can cause human errors. According to related studies, written manuals or operating procedures are revealed as one of the most important factors, and the understandability is pointed out as one of the major reasons for procedure-related human errors. Many qualitative checklists are suggested to evaluate emergency operating procedures (EOPs) of NPPs. However, since qualitative evaluations using checklists have some drawbacks, a quantitative measure that can quantify the complexity of EOPs is very necessary to compensate for them. In order to quantify the complexity of steps included in EOPs, Park et al. suggested the step complexity (SC) measure. In addition, to ascertain the appropriateness of the SC measure, averaged step performance time data obtained from emergency training records for the loss of coolant accident and the excess steam dump event were compared with estimated SC scores. Although averaged step performance time data show good correlation with estimated SC scores, conclusions for some important issues that have to be clarified to ensure the appropriateness of the SC measure were not properly drawn because of lack of backup data. In this paper, to clarify remaining issues, additional activities to verify the appropriateness of the SC measure are performed using averaged step performance time data obtained from emergency training records. The total number of available records is 36, and training scenarios are the steam generator tube rupture and the loss of all feedwater. The number of scenarios is 18 each. From these emergency training records, averaged step performance time data for 30 steps are retrieved. As the results, the SC measure shows statistically meaningful

Explosive Forming of Low Carbon Steel Sheet into a Stepped Disc Shape

OpenAIRE

S. Balasubramanian; S. Sarvat Ali; E.S. Bhagiradha Rao

1984-01-01

This paper deals with the explosive forming of deep drawing quality steel into a two stepped disc type shape. An attempt has been made to predict the forming parameters from theoretical considerations by equating the disc shape with an equivalent dome. Results of forming this shape in a single stage vis-a-vis forming in two stages are compared.

Evaluation of a two-step thermal method for separating organic and elemental carbon for radiocarbon analysis

NARCIS (Netherlands)

Dusek, U.; Monaco, M.; Prokopiou, M.; Gongriep, F.; Hitzenberger, R.; Meijer, H. A. J.; Rockmann, T.

2014-01-01

We thoroughly characterized a system for thermal separation of organic carbon (OC) and elemental carbon (EC) for subsequent radiocarbon analysis. Different organic compounds as well as ambient aerosol filter samples were introduced into an oven system and combusted to CO2 in pure O-2. The main

Determinants of limb preference for initiating compensatory stepping poststroke.

Science.gov (United States)

Mansfield, Avril; Inness, Elizabeth L; Lakhani, Bimal; McIlroy, William E

2012-07-01

To investigate the determinants of limb preference for initiating compensatory stepping poststroke. Retrospective chart review. Inpatient rehabilitation. Convenience sample of individuals admitted to inpatient rehabilitation with poststroke hemiparesis. Not applicable. Compensatory stepping responses were evoked using a lean-and-release postural perturbation. The limb used to initiate compensatory stepping was determined. The relationships between stepping with the paretic limb and premorbid limb dominance, weight bearing on the paretic limb in quiet standing, ability to bear weight on the paretic limb, preperturbation weight bearing on the paretic limb, and lower-limb motor recovery scores were determined. The majority (59.1%) of responses were steps initiated with the nonparetic limb. Increased lower-limb motor recovery scores and preperturbation weight bearing on the nonparetic limb were significantly related to increased frequency of stepping with the paretic limb. When the preferred limb was physically blocked, an inappropriate response was initiated in 21% of trials (ie, nonstep responses or an attempt to step with the blocked limb). This study reveals the challenges that individuals with poststroke hemiparesis face when executing compensatory stepping responses to prevent a fall after a postural perturbation. The inability or challenges to executing a compensatory step with the paretic limb may increase the risk for falls poststroke. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Fully solar-driven thermo- and electrochemistry for advanced oxidation processes (STEP-AOPs) of 2-nitrophenol wastewater.

Science.gov (United States)

Nie, Chunhong; Shao, Nan; Wang, Baohui; Yuan, Dandan; Sui, Xin; Wu, Hongjun

2016-07-01

The STEP (Solar Thermal Electrochemical Process) for Advanced Oxidation Processes (AOPs, combined to STEP-AOPs), fully driven by solar energy without the input of any other forms of energy and chemicals, is introduced and demonstrated from the theory to experiments. Exemplified by the persistent organic pollutant 2-nitrophenol in water, the fundamental model and practical system are exhibited for the STEP-AOPs to efficiently transform 2-nitrophenol into carbon dioxide, water, and the other substances. The results show that the STEP-AOPs system performs more effectively than classical AOPs in terms of the thermodynamics and kinetics of pollutant oxidation. Due to the combination of solar thermochemical reactions with electrochemistry, the STEP-AOPs system allows the requisite electrolysis voltage of 2-nitrophenol to be experimentally decreased from 1.00 V to 0.84 V, and the response current increases from 18 mA to 40 mA. STEP-AOPs also greatly improve the kinetics of the oxidation at 30 °C and 80 °C. As a result, the removal rate of 2-nitrophenol after 1 h increased from 19.50% at 30 °C to 32.70% at 80 °C at constant 1.90 V. Mechanistic analysis reveals that the oxidation pathway is favorably changed because of thermal effects. The tracking of the reaction displayed that benzenediol and hydroquinone are initial products, with maleic acid and formic acid as sequential carboxylic acid products, and carbon dioxide as the final product. The theory and experiments on STEP-AOPs system exemplified by the oxidation of 2-nitrophenol provide a broad basis for extension of the STEP and AOPs for rapid and efficient treatment of organic wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

A description and comparison of selected forest carbon registries: a guide for States considering the development of a forest carbon registry

Science.gov (United States)

Jessica Call; Jennifer Hayes

2007-01-01

There is increasing interest in tools for measuring and reducing emissions of carbon dioxide, a major greenhouse gas. Two tools that have been receiving a lot of attention include carbon markets and carbon registries. Carbon registries are established to record and track net carbon emission levels over time. These registries provide quantifiable and verifiable carbon...

Developing countries are combating climate change. Actions in developing countries that slow growth in carbon emissions

International Nuclear Information System (INIS)

Reid, Walter V.; Goldemberg, Jose

1998-01-01

The role of developing countries in helping to solve the problem of climate change is increasingly a focus of political controversy. With levels of greenhouse gas emissions projected to exceed those of developed countries by 2020, some industrialized countries are calling on developing countries to take stronger action to meet the commitments they have made in the Framework Convention on Climate Change (FCCC). This review of recent policy changes in developing countries, however, suggests that they are already taking little appreciated steps that reduce rates of growth in carbon emissions. Indeed, since the 1992 signing of the FCCC, carbon emission savings in developing countries may be greater than those attained by industrialized countries. A major source of these gains can be attributed to energy price reforms that are likely to have led to substantial gains in production and end-use efficiency. (author)

Carbon dioxide sequestration using NaHSO4 and NaOH: A dissolution and carbonation optimisation study.

Science.gov (United States)

Sanna, Aimaro; Steel, Luc; Maroto-Valer, M Mercedes

2017-03-15

The use of NaHSO 4 to leach out Mg fromlizardite-rich serpentinite (in form of MgSO 4 ) and the carbonation of CO 2 (captured in form of Na 2 CO 3 using NaOH) to form MgCO 3 and Na 2 SO 4 was investigated. Unlike ammonium sulphate, sodium sulphate can be separated via precipitation during the recycling step avoiding energy intensive evaporation process required in NH 4 -based processes. To determine the effectiveness of the NaHSO 4 /NaOH process when applied to lizardite, the optimisation of the dissolution and carbonation steps were performed using a UK lizardite-rich serpentine. Temperature, solid/liquid ratio, particle size, concentration and molar ratio were evaluated. An optimal dissolution efficiency of 69.6% was achieved over 3 h at 100 °C using 1.4 M sodium bisulphate and 50 g/l serpentine with particle size 75-150 μm. An optimal carbonation efficiency of 95.4% was achieved over 30 min at 90 °C and 1:1 magnesium:sodium carbonate molar ratio using non-synthesised solution. The CO 2 sequestration capacity was 223.6 g carbon dioxide/kg serpentine (66.4% in terms of Mg bonded to hydromagnesite), which is comparable with those obtained using ammonium based processes. Therefore, lizardite-rich serpentinites represent a valuable resource for the NaHSO 4 /NaOH based pH swing mineralisation process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermal hydrolysis of sludge and the use of hydrolysate as carbon source for denitrification

Energy Technology Data Exchange (ETDEWEB)

Barlindhaug, J

1995-10-01

As a consequence of the North Sea- and the Baltic Sea Treaties as well as the Wastewater Directive of the EU, several large wastewater treatment plants discharging to sensitive receiving waters have to include phosphorus as well as nitrogen removal. This thesis evaluates the so called NTH-process for nutrient removal. In this process pre-precipitation is used in front of a biological nitrogen removal step that is based on a combination of pre- and post-denitrification in moving bed biofilm reactors. The biological step is followed by a final separation step, possibly after coagulant addition. Carbon source for the post denitrification step is made available by hydrolysis of the sludge produced. The idea is that the particulate organic matter, which in a traditional pre-denitrification step would have to be enzymatically hydrolyzed, can be more efficiently hydrolyzed in a concentrated sidestream and used in a post-denitrification step. In the thesis hydrolyzed sludge is used as a carbon source for denitrification. The objective is to investigate the influence of varying hydrolysis conditions on the composition and amount of the thermal hydrolysate produced, as well as the quality of the hydrolysate as a carbon source for denitrification. 201 refs., 78 refs., 53 tabs.

The role of carbon in the breakaway oxidation of mild steel in high pressure carbon dioxide

International Nuclear Information System (INIS)

Surman, P.L.; Brown, A.M.

1974-01-01

The rate controlling step in the oxidation of iron and mild steel in CO 2 is the diffusion of iron across the inner of two layers of magnetite scale. Cation diffusion is directed towards available oxidant and hence tends to produce fresh oxide in freely available space. The initial oxidation process is thus protective and stress-free. As oxidation proceeds the gaseous reaction product, carbon monoxide, tends to accumulate at the oxide/metal interface. Eventually this leads to simultaneous carbon deposition and oxide formation. This carbon contamination allows oxidant access to oxide crystallite 'jacking points', and hence volume expansion and stressed breakaway corrosion can occur. Experiments designed to simulate the promotion, propagation and healing of breakaway oxidation and to define the conditions for carbon deposition are reported. (author)

Deposition Diagnostics for Next-step Devices

International Nuclear Information System (INIS)

Skinner, C.H.; Roquemore, A.L.; Bader, A.; Wampler, W.R.

2004-01-01

The scale-up of deposition in next-step devices such as ITER will pose new diagnostic challenges. Codeposition of hydrogen with carbon needs to be characterized and understood in the initial hydrogen phase in order to mitigate tritium retention and qualify carbon plasma facing components for DT operations. Plasma facing diagnostic mirrors will experience deposition that is expected to rapidly degrade their reflectivity, posing a new challenge to diagnostic design. Some eroded particles will collect as dust on interior surfaces and the quantity of dust will be strictly regulated for safety reasons - however diagnostics of in-vessel dust are lacking. We report results from two diagnostics that relate to these issues. Measurements of deposition on NSTX with 4 Hz time resolution have been made using a quartz microbalance in a configuration that mimics that of a typical diagnostic mirror. Often deposition was observed immediately following the discharge suggesting that diagnostic shutters should be closed as soon as possible after the time period of interest. Material loss was observed following a few discharges. A novel diagnostic to detect surface particles on remote surfaces was commissioned on NSTX

Development of a thermal method for the measurement of elemental carbon

Energy Technology Data Exchange (ETDEWEB)

Lavanchy, V.M.H. [Bern Univ. (Switzerland); Baltensperger, U.; Gaeggeler, H.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-09-01

A thermal method was developed to measure the organic carbon (OC) and elemental carbon (EC) content of atmospheric aerosols. OC is first oxidized under an O{sub 2} flow during a precombustion step and measured with an Non-Dispersive Infrared Analyzer (NDIR). The remaining carbon, defined as EC, is then oxidized at 650{sup o}C. (author) 1 fig., 1 tab., 3 refs.

Carbon fiber monocoque for a hydrogen prototype for low consumption challenge

Energy Technology Data Exchange (ETDEWEB)

Airale, A.; Scattina, A. [Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Carello, M.

2011-05-15

Weight reduction and high mechanics performance are one of the challenges of the automotive industries future. A particular and interesting field is the application of carbon fibres in combination with structural foams. These allow to realize creative shapes for the car body but also strength and tough elements for the chassis, according to the necessity to combine style with design and engineering aspects. Nowadays, the problem of carbon fibre technology is the cost of production and the recyclability, so the major applications are in the racing field. One interesting application is the body of the prototype called IDRA, a low consumption vehicle which participated in the European Shell Eco-marathon. The chassis is a structural frame made with structural foam, the body is a part of the chassis and it is made of carbon fibre. The result is a well made car body integrated with all the sub-systems: steering, brakes, wheels, cockpit, electric wiring, controls, fuel cell, electric motor and transmission. The different design and production steps, from the concept phase and structural analysis made by means of finite element techniques to the production and the assembling of the monocoque, are discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The origins and behaviour of carbon in a major semi-arid river, the Murray River, Australia, as constrained by carbon isotopes and hydrochemistry

International Nuclear Information System (INIS)

Cartwright, Ian

2010-01-01

Research highlights: → δ 13 C and concentrations of DIC in Murray River controlled by mineralisation of organic carbon and evasion. → Murray River is source of atmospheric CO 2 . → In-river processing of carbon results in difficulties in determining carbon sources. - Abstract: δ 13 C values of dissolved inorganic C (DIC), dissolved organic C (DOC), and particulate organic C (POC) together with δ 18 O and δ 2 H values of water, δ 34 S values of dissolved SO 4 , and major ion concentrations were measured in the Murray River and its tributaries between November 2005 and April 2007 to constrain the origins and behaviour of riverine C. δ 13 C DIC values in the Murray River vary between -9.5 and -4.7 per mille with a range of 13 C DIC values of the tributaries are -11.0 per mille to -5.1 per mille. DIC concentrations of the Murray River increase from ∼25 mg/L in the middle and upper reaches of the river to 45-55 mg/L in the lower reaches. However, the mass ratio of DIC as a proportion of the total dissolved solids (TDS) decreases from ∼0.6-0.7 in the headwaters to ∼0.2-0.3 in the lower reaches of the river, with similar downstream changes in DIC/Cl ratios. This precludes simple evaporative concentration of DIC and is interpreted as the river evading CO 2 ; this interpretation is consistent with pCO 2 values that are in the range 550-11,200 ppm volume (ppmv), which are far higher than those in equilibrium with the atmosphere (∼360 ppmv). The δ 13 C DIC values are similar to those that would be produced by the weathering of marine limestone (δ 13 C ∼ 0 per mille). However, the lack of marine limestones cropping out in the Murray-Darling Basin and the relatively uniform δ 13 C DIC values of the Murray River (even in upland reaches where the dominant rock types are metamorphosed silicates and granites) make this unlikely. Rather the high pCO 2 values and δ 13 C DIC values are best explained by a combination of mineralisation of low δ 13 C organic C

Carbon monoxide budget in the northern hemisphere

Energy Technology Data Exchange (ETDEWEB)

Bakwin, P.S.; Tans, P.P. (Climate Monitoring and Diagnostics Lab., Boulder, CO (United States)); Novelli, P.C. (Univ. of Colorado, Boulder, CO (United States))

1994-03-15

To improve urban air quality the major industrialized nations of the West took steps during the 1970s and 1980s to reduce carbon monoxide (CO) emissions from automobiles and other industrial sources. Overall, CO/CO[sub 2] emission ratios from the mix of fossil fuel combustion sources have been reduced by about half during 1976-1990. Also, the tropospheric abundance of hydroxyl radical (OH), which is the main sink for CO, is proposed to have increased globally by about 1.0 [+-] 0.8% yr[sup [minus]1]. The authors use a simple two-box model to examine the impact of shrinking emissions and increasing OH on the global abundance of CO. They find that these factors contribute about equally in reducing CO levels in the Northern Hemisphere troposphere by about 1.8 [+-] 0.8 ppb yr[sup [minus]1] on average. 19 refs., 1 fig.

Integration of Porous Carbon Nanowrinkles into Carbon Micropost Array for Microsupercapacitors

Directory of Open Access Journals (Sweden)

Shuang Xi

2018-01-01

Full Text Available Porous carbon nanowrinkles (PCW coated on carbon micropost (CMP arrays were successfully fabricated via three-step process, which took advantages of the large difference in elastic moduli between PCW and the raw material of CMP. The effect of nanowrinkle integration on the electrochemical performances was investigated, showing an improved electrochemical performance. The electrode also shows excellent cycling stability, which retains 84% of its initial discharge capacitance after 1700 cycles with >90% Coulombic efficiency. This enhanced electrochemical performance is ascribed to the synergistic effect of enlarged surface area and porous structure of PCW. The obtained PCW/CMP compositing electrode with the advantages of low cost and easy scaling-up has great potential for on-chip supercapacitors.

The Biosynthesis of Nitrogen-, Sulfur-, and High-carbon Chain-containing Sugars†

Science.gov (United States)

Lin, Chia-I; McCarty, Reid M.; Liu, Hung-wen

2013-01-01

Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition: (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and “high-carbon” chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered “rare” due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains. PMID:23348524

Co@Carbon and Co 3 O4@Carbon nanocomposites derived from a single MOF for supercapacitors.

Science.gov (United States)

Dai, Engao; Xu, Jiao; Qiu, Junjie; Liu, Shucheng; Chen, Ping; Liu, Yi

2017-10-03

Developing a composite electrode containing both carbon and transition metal/metal oxide as the supercapacitor electrode can combine the merits and mitigate the shortcomings of both the components. Herein, we report a simple strategy to prepare the hybrid nanostructure of Co@Carbon and Co 3 O 4 @Carbon by pyrolysis a single MOFs precursor. Co-based MOFs (Co-BDC) nanosheets with morphology of regular parallelogram slice have been prepared by a bottom-up synthesis strategy. One-step pyrolysis of Co-BDC, produces a porous carbon layer incorporating well-dispersed Co and Co 3 O 4 nanoparticles. The as-prepared cobalt-carbon composites exhibit the thin layer morphology and large specific surface area with hierarchical porosity. These features significantly improve the ion-accessible surface area for charge storage and shorten the ion transport length in thin dimension, thus contributing to a high specific capacitance. Improved capacitance performance was successfully realized for the asymmetric supercapacitors (ASCs) (Co@Carbon//Co 3 O 4 @Carbon), better than those of the symmetric supercapacitors (SSCs) based on Co@Carbon and Co 3 O 4 @Carbon materials (i.e., Co@Carbon//Co@Carbon and Co 3 O 4 @Carbon//Co 3 O 4 @Carbon). The working voltage of the ASCs can be extended to 1.5 V and show a remarkable high power capability in aqueous electrolyte. This work provides a controllable strategy for nanostructured carbon-metal and carbon-metal oxide composite electrodes from a single precursor.

Carbon uptake by mature Amazon forests has mitigated Amazon nations' carbon emissions.

Science.gov (United States)

Phillips, Oliver L; Brienen, Roel J W

2017-12-01

Several independent lines of evidence suggest that Amazon forests have provided a significant carbon sink service, and also that the Amazon carbon sink in intact, mature forests may now be threatened as a result of different processes. There has however been no work done to quantify non-land-use-change forest carbon fluxes on a national basis within Amazonia, or to place these national fluxes and their possible changes in the context of the major anthropogenic carbon fluxes in the region. Here we present a first attempt to interpret results from ground-based monitoring of mature forest carbon fluxes in a biogeographically, politically, and temporally differentiated way. Specifically, using results from a large long-term network of forest plots, we estimate the Amazon biomass carbon balance over the last three decades for the different regions and nine nations of Amazonia, and evaluate the magnitude and trajectory of these differentiated balances in relation to major national anthropogenic carbon emissions. The sink of carbon into mature forests has been remarkably geographically ubiquitous across Amazonia, being substantial and persistent in each of the five biogeographic regions within Amazonia. Between 1980 and 2010, it has more than mitigated the fossil fuel emissions of every single national economy, except that of Venezuela. For most nations (Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname) the sink has probably additionally mitigated all anthropogenic carbon emissions due to Amazon deforestation and other land use change. While the sink has weakened in some regions since 2000, our analysis suggests that Amazon nations which are able to conserve large areas of natural and semi-natural landscape still contribute globally-significant carbon sequestration. Mature forests across all of Amazonia have contributed significantly to mitigating climate change for decades. Yet Amazon nations have not directly benefited from providing this global scale

Preparation of very pure active carbon

International Nuclear Information System (INIS)

Sloot, H.A. van der; Hoede, D.; Zonderhuis, J.; Meijer, C.

1980-02-01

The preparation of very pure active carbon is described. Starting from polyvinylidene chloride active carbon is prepared by carbonization in a nitrogen atmosphere, grinding, sieving and activation of the powder fraction with CO 2 at 950 0 to approximately 50% burn-off. The concentrations of trace and major elements are reduced to the ppb and ppm level, respectively. In the present set-up 100 g of carbon grains and approximately 50 g of active carbon powder can be produced weekly

On the motion of internal carbonation layers

NARCIS (Netherlands)

Muntean, A.; Böhm, M.; Schmidt, A.; Franke, L.; Deckelmann, G.; Espinoza-Marzal, R.

2009-01-01

Carbonation is the reaction of environmental carbon dioxide with alkaline species in concrete. It is one of the major processes affecting the concrete durability. In this note, we review a few modelling strategies that are behind conceptually different carbonation models which are all able to

Suspended 3D pyrolytic carbon microelectrodes for electrochemistry

DEFF Research Database (Denmark)

Hemanth, Suhith; Caviglia, Claudia; Keller, Stephan Sylvest

2017-01-01

with cyclic voltammetry (CV) and impedance spectroscopy (EIS) using potassium ferri-ferrocyanide redox probe in a custom made batch system with magnetic clamping. Different 3D pyrolytic carbon microelectrodes were compared and the optimal design displayed twice the peak current and half the charge transfer......Carbon microelectrodes have a wide range of applications because of their unique material properties and biocompatibility. This work presents the fabrication and characterization of suspended pyrolytic carbon microstructures serving as three-dimensional (3D) carbon microelectrodes...... for electrochemical applications. A 3D polymer template in epoxy based photoresist (SU-8) was fabricated with multiple steps of UV photolithography and pyrolysed at 900 °C to obtain 3D carbon microelectrodes. The pyrolytic carbon microstructures were characterized by SEM, Raman spectroscopy and XPS to determine...

Characterization of carbonated serpentine using XPS and TEM

International Nuclear Information System (INIS)

Schulze, Roland K.; Hill, Mary Ann; Field, Robert D.; Papin, Pallas A.; Hanrahan, Robert J.; Byler, Darrin D.

2004-01-01

With the increasing concentration volume of carbon dioxide in the atmosphere, there has been an increasing interest in carbon dioxide sequestration. One method is to store the carbon dioxide in mineral form, reacting solution dissolved CO 2 to precipitate carbonates. In order to understand whether or not such an endeavor is feasible, the carbonation reaction must first be understood. In this study, the surface of ground serpentine, untreated, heat treated and following a carbonation experiment, has been characterized using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results indicate that the mechanism for the reaction involves dissolution of the serpentine through the formation of an amorphous phase and subsequent precipitation of magnesite. The rate limiting step appears to be the diffusion of Mg out of the amorphous phase

One-step hydrothermal synthesis of three-dimensional porous Ni-Co sulfide/reduced graphene oxide composite with optimal incorporation of carbon nanotubes for high performance supercapacitors

Science.gov (United States)

Chiu, Cheng-Ting; Chen, Dong-Hwang

2018-04-01

Three-dimensional (3D) porous Ni-Co sulfide/reduced graphene oxide composite with the appropriate incorporation of carbon nanotubes (NCS/rGO/CNT) was fabricated as a promising material for supercapacitor electrodes. It combined the high pseudo-capacitance of Ni-Co sulfide as well as the large specific surface area and electrical double layer capacitance of reduced graphene oxide (rGO). Carbon nanotubes (CNTs) were incorporated to act as the spacer for hindering the restacking of rGO and to construct a conductive network for enhancing the electron transport. The 3D porous NCS/rGO/CNT composite was fabricated by a facile one-step hydrothermal process in which Ni-Co sulfide nanosheets were synthesized and graphene oxide was reduced simultaneously. It was shown that the capacitance and cyclic performance indeed could be effectively improved via the appropriate addition of CNTs. In addition, a flexible all-solid-state asymmetric supercapacitor based on the NCS/rGO/CNT electrode was fabricated and exhibited the same capacitive electrochemical performance under bending. Also, it could successfully turn on a light-emitting diode light, revealing its feasibility in practical application. All results demonstrated that the developed NCS/rGO/CNT composite has potential application in supercapacitors.

Single-Step Fabrication Using a Phase Inversion Method of Poly(vinylidene fluoride) (PVDF) Activated Carbon Air Cathodes for Microbial Fuel Cells

KAUST Repository

Yang, Wulin

2014-10-14

Air cathodes used in microbial fuel cells (MFCs) need to have high catalytic activity for oxygen reduction, but they must also be easy to manufacture, inexpensive, and watertight. A simple one-step, phase inversion process was used here to construct an inexpensive MFC cathode using a poly(vinylidene fluoride) (PVDF) binder and an activated carbon catalyst. The phase inversion process enabled cathode preparation at room temperatures, without the need for additional heat treatment, and it produced for the first time a cathode that did not require a separate diffusion layer to prevent water leakage. MFCs using this new type of cathode produced a maximum power density of 1470 ± 50 mW m–2 with acetate as a substrate, and 230 ± 10 mW m–2 with domestic wastewater. These power densities were similar to those obtained using cathodes made using more expensive materials or more complex procedures, such as cathodes with a polytetrafluoroethylene (PTFE) binder and a poly(dimethylsiloxane) (PDMS) diffusion layer, or a Pt catalyst. Even though the PVDF cathodes did not have a diffusion layer, they withstood up to 1.22 ± 0.04 m of water head (∼12 kPa) without leakage, compared to 0.18 ± 0.02 m for cathodes made using PTFE binder and PDMS diffusion layer. The cost of PVDF and activated carbon ($3 m–2) was less than that of the stainless steel mesh current collector ($12 m–2). PVDF-based AC cathodes therefore are inexpensive, have excellent performance in terms of power and water leakage, and they can be easily manufactured using a single phase inversion process at room temperature.

Step-by-step seeding procedure for preparing HKUST-1 membrane on porous α-alumina support.

Science.gov (United States)

Nan, Jiangpu; Dong, Xueliang; Wang, Wenjin; Jin, Wanqin; Xu, Nanping

2011-04-19

Metal-organic framework (MOF) membranes have attracted considerable attention because of their striking advantages in small-molecule separation. The preparation of an integrated MOF membrane is still a major challenge. Depositing a uniform seed layer on a support for secondary growth is a main route to obtaining an integrated MOF membrane. A novel seeding method to prepare HKUST-1 (known as Cu(3)(btc)(2)) membranes on porous α-alumina supports is reported. The in situ production of the seed layer was realized in step-by-step fashion via the coordination of H(3)btc and Cu(2+) on an α-alumina support. The formation process of the seed layer was observed by ultraviolet-visible absorption spectroscopy and atomic force microscopy. An integrated HKUST-1 membrane could be synthesized by the secondary hydrothermal growth on the seeded support. The gas permeation performance of the membrane was evaluated. © 2011 American Chemical Society

Reactor design considerations in mineral sequestration of carbon dioxide

International Nuclear Information System (INIS)

Ityokumbul, M.T.; Chander, S.; O'Connor, William K.; Dahlin, David C.; Gerdemann, Stephen J.

2001-01-01

One of the promising approaches to lowering the anthropogenic carbon dioxide levels in the atmosphere is mineral sequestration. In this approach, the carbon dioxide reacts with alkaline earth containing silicate minerals forming magnesium and/or calcium carbonates. Mineral carbonation is a multiphase reaction process involving gas, liquid and solid phases. The effective design and scale-up of the slurry reactor for mineral carbonation will require careful delineation of the rate determining step and how it changes with the scale of the reactor. The shrinking core model was used to describe the mineral carbonation reaction. Analysis of laboratory data indicates that the transformations of olivine and serpentine are controlled by chemical reaction and diffusion through an ash layer respectively. Rate parameters for olivine and serpentine carbonation are estimated from the laboratory data

Vertically aligned multiwalled carbon nanotubes as electronic interconnects

Science.gov (United States)

Gopee, Vimal Chandra

was critical for bonding carbon nanotubes to sintered silver. A step by step process is described that allows the production of solder-carbon nanotubes and silver-carbon nanotubes interconnects. 4-point probe electrical characterisation of the interconnects was performed and the interconnects were shown to have a resistivity of 5.0 x 10-4 Ωcm for solder-carbon nanotubes and 5.2 x 10-4 Ωcm for silver-carbon nanotubes interconnects. Ramp to failure tests carried out on solder-carbon nanotubes interconnects showed current carrying capacity of 0.75 MA/cm2, only one order of magnitude lower than copper.

Water-carbon Links in a Tropical Forest: How Interbasin Groundwater Flow Affects Carbon Fluxes and Ecosystem Carbon Budgets

Energy Technology Data Exchange (ETDEWEB)

Genereux, David [North Carolina State Univ., Raleigh, NC (United States); Osburn, Christopher [North Carolina State Univ., Raleigh, NC (United States); Oberbauer, Steven [Florida Intl Univ., Miami, FL (United States); Oviedo Vargas, Diana [North Carolina State Univ., Raleigh, NC (United States); Dierick, Diego [Florida Intl Univ., Miami, FL (United States)

2017-03-27

This report covers the outcomes from a quantitative, interdisciplinary field investigation of how carbon fluxes and budgets in a lowland tropical rainforest are affected by the discharge of old regional groundwater into streams, springs, and wetlands in the forest. The work was carried out in a lowland rainforest of Costa Rica, at La Selva Biological Station. The research shows that discharge of regional groundwater high in dissolved carbon dioxide represents a significant input of carbon to the rainforest "from below", an input that is on average larger than the carbon input "from above" from the atmosphere. A stream receiving discharge of regional groundwater had greatly elevated emissions of carbon dioxide (but not methane) to the overlying air, and elevated downstream export of carbon from its watershed with stream flow. The emission of deep geological carbon dioxide from stream water elevates the carbon dioxide concentrations in air above the streams. Carbon-14 tracing revealed the presence of geological carbon in the leaves and stems of some riparian plants near streams that receive inputs of regional groundwater. Also, discharge of regional groundwater is responsible for input of dissolved organic matter with distinctive chemistry to rainforest streams and wetlands. The discharge of regional groundwater in lowland surface waters has a major impact on the carbon cycle in this and likely other tropical and non-tropical forests.

Step dynamics and terrace-width distribution on flame-annealed gold films: The effect of step-step interaction

International Nuclear Information System (INIS)

Shimoni, Nira; Ayal, Shai; Millo, Oded

2000-01-01

Dynamics of atomic steps and the terrace-width distribution within step bunches on flame-annealed gold films are studied using scanning tunneling microscopy. The distribution is narrower than commonly observed for vicinal planes and has a Gaussian shape, indicating a short-range repulsive interaction between the steps, with an apparently large interaction constant. The dynamics of the atomic steps, on the other hand, appear to be influenced, in addition to these short-range interactions, also by a longer-range attraction of steps towards step bunches. Both types of interactions promote self-ordering of terrace structures on the surface. When current is driven through the films a step-fingering instability sets in, reminiscent of the Bales-Zangwill instability

Tritium inventory and recovery in next-step fusion devices

International Nuclear Information System (INIS)

Causey, R.A.; Brooks, J.N.; Federici, G.

2002-01-01

Future fusion devices will use tritium and deuterium fuel. Because tritium is both radioactive and expensive, it is absolutely necessary that there be an understanding of the tritium retention characteristics of the materials used in these devices as well as how to recover the tritium. There are three materials that are strong candidates for plasma-facing-material use in next-step fusion devices. These are beryllium, tungsten, and carbon. While beryllium has the disadvantage of high sputtering and low melting point (which limits its power handling capabilities in divertor areas), it has the advantages of being a low-Z material with a good thermal conductivity and the ability to get oxygen from the plasma. Due to beryllium's very low solubility for hydrogen, implantation of beryllium with deuterium and tritium results in a saturated layer in the very near-surface with limited inventory (J. Nucl. Mater. 273 (1999) 1). Unfortunately, there are nuclear reactions generated by neutrons that will breed tritium and helium in the material bulk (J. Nucl. Mater. 179 (1991) 329). This process will lead to a substantial tritium inventory in the bulk of the beryllium after long-term neutron exposure (i.e. well beyond the operation life time of a next-step reactor like ITER). Tungsten is a high-Z material that will be used in the divertor region of next-step devices (e.g. ITER) and possibly as a first wall material in later devices. The divertor is the preferred location for tungsten use because net erosion is very low there due to low sputtering and high redeposition. While experiments are still continuing on tritium retention in tungsten, present data suggest that relatively low tritium inventories will result with this material (J. Nucl. Mater. 290-293 (2001) 505). For tritium inventories, carbon is the problem material. Neutron damage to the graphite can result in substantial bulk tritium retention (J. Nucl. Mater. 191-194 (1992) 368), and codeposition of the sputtered carbon

Traffic safety and step-by-step driving licence for young people

DEFF Research Database (Denmark)

Tønning, Charlotte; Agerholm, Niels

2017-01-01

presents a review of safety effects from step-by-step driving licence schemes. Most of the investigated schemes consist of a step-by-step driving licence with Step 1) various tests and education, Step 2) a period where driving is only allowed together with an experienced driver and Step 3) driving without...... companion is allowed but with various restrictions and, in some cases, additional driving education and tests. In general, a step-by-step driving licence improves traffic safety even though the young people are permitted to drive a car earlier on. The effects from driving with an experienced driver vary......Young novice car drivers are much more accident-prone than other drivers - up to 10 times that of their parents' generation. A central solution to improve the traffic safety for this group is implementation of a step-by-step driving licence. A number of countries have introduced a step...

Mechanisms of aqueous wollastonite carbonation as a possible CO2 sequestration process

International Nuclear Information System (INIS)

Huijgen, W.J.J.; Comans, R.N.J.; Witkamp, G.J.

2006-02-01

The mechanisms of aqueous wollastonite carbonation as a possible carbon dioxide sequestration process were investigated experimentally by systematic variation of the reaction temperature, CO2 pressure, particle size, reaction time, liquid to solid ratio and agitation power. The carbonation reaction was observed to occur via the aqueous phase in two steps: (1) Ca leaching from the CaSiO3 matrix and (2) CaCO3 nucleation and growth. Leaching is hindered by a Ca-depleted silicate rim resulting from incongruent Ca-dissolution. Two temperature regimes were identified in the overall carbonation process. At temperatures below an optimum reaction temperature, the overall reaction rate is probably limited by the leaching rate of Ca. At higher temperatures, nucleation and growth of calcium carbonate is probably limiting the conversion, due to a reduced (bi)carbonate activity. The mechanisms for the aqueous carbonation of wollastonite were shown to be similar to those reported previously for an industrial residue and a Mg-silicate. The carbonation of wollastonite proceeds rapidly relative to Mg-silicates, with a maximum conversion in 15 min of 70% at 200C, 20 bar CO2 partial pressure and a particle size of <38 μm. The obtained insight in the reaction mechanisms enables the energetic and economic assessment of CO2 sequestration by wollastonite carbonation, which forms an essential next step in its further development

Use of grape must as a binder to obtain activated carbon briquettes

Directory of Open Access Journals (Sweden)

Deiana A. C.

2004-01-01

Full Text Available The results of studies on briquetting activated-carbon-based adsorbent materials, prepared from raw materials from the region of Cuyo, Argentina, are reported in this article. Several steps were carried out to obtain activated-carbon briquettes from Eucalyptus camaldulensis Dehn wood. These steps included carbonization of wood to obtain char; blending of char and a novel binder, i.e., grape must; formation of cylinder-like briquettes by pressure; and activation of the resulting material. The material was activated with steam under different temperatures, activation times, and activating agent flow rates. Impact resistance index, axial compressive strength, tensile strength by diametrical compression, BET area, and pore volume were measured for product characterization. Satisfactory surface areas and mechanical strengths were found in the final products.

Carbonate-silicate cycle models of the long-term carbon cycle, carbonate accumulation in the oceans, and climate

International Nuclear Information System (INIS)

Caldeira, K.G.

1991-01-01

Several models of the long-term carbon cycle, incorporating models of the carbonate-silicate cycle, were developed and utilized to investigate issues relating to global climate and the causes and consequences of changes in calcium carbonate accumulation in the oceans. Model results indicate that the marked mid-Cretaceous (120 Ma) global warming could be explained by increased rates of release of carbon dioxide from subduction-zone metamorphism and mid-ocean-ridges, in conjunction with paleogeographic factors. Since the mid-Cretaceous, the primary setting for calcium carbonate accumulation in the oceans has shifted from shallow-water to deep-water environments. Model results suggest that this shift could have major consequences for the carbonate-silicate cycle and climate, and lead to significant increases in the flux of metamorphic carbon dioxide to the atmosphere. Increases in pelagic carbonate productivity, and decreases in tropical shallow-water area available for neritic carbonate accumulation, have both been proposed as the primary cause of this shift. Two lines of evidence developed here (one involving a statistical analysis of Tertiary carbonate-accumulation and oxygen-isotope data, and another based on modeling the carbonate-silicate cycle and ocean chemistry) suggest that a decrease in tropical shallow-water area was more important than increased pelagic productivity in explaining this shift. Model investigations of changes in ocean chemistry at the Cretaceous/Tertiary (K/T) boundary (66 Ma) indicate that variations in deep-water carbonate productivity may affect shallow-water carbonate accumulation rates through a mechanism involving surface-water carbonate-ion concentration. In the aftermath of the K/T boundary event, deep-water carbonate production and accumulation were significantly reduced as a result of the extinction of calcareous plankton

Carbonation of Mg(OH){sub 2} in a pressurised fluidised bed for CO{sub 2} sequestration

Energy Technology Data Exchange (ETDEWEB)

Fagerlund, J.

2012-07-01

To date, a number of methods to accelerate natural weathering or in other words increase the CO{sub 2} uptake rate of various minerals have been suggested; commonly this is known as mineral carbonation or CO{sub 2} mineralisation. A brief literature review of recently published articles in this field is presented, showing that the interest in mineral carbonation is increasing. However, it should be noted that mineral carbonation is only one option in a larger portfolio of various carbon dioxide capture and storage (CCS) alternatives. Unlike many other options, the CO{sub 2} mineralisation option considered in this thesis is largely founded on the possibility to utilise the exothermic nature of magnesium carbonation and based on this notion, it has been divided into three steps. The first two steps are energy demanding, while the third step is energy 'negative', and in theory, the source of the energy required in the first two steps. Unfortunately, however, the energy demanded by the first two steps, Mg extraction and Mg(OH){sub 2} production, is (currently) much higher than what could be generated by the subsequent Mg(OH){sub 2} carbonation step. Nevertheless, opportunities to reduce the energy intensity of the process in question are still being investigated, and while an energy-neutral carbonation process might be difficult to achieve, energy requirements can still be rendered industrially acceptable (and comparable to or even better than for other CCS methods). The main focus of this thesis lies with the third step, Mg(OH){sub 2} carbonation, which is performed using a pressurised fluidised bed (PFB). The elevated CO{sub 2} pressure conditions (typically approx 20 bar) allow for the carbonation reaction to take place at higher temperatures (typically approx 500 deg C) than otherwise due to thermodynamic constraints on carbonate stability. The increase in reaction rate as a function of temperature follows the Arrhenius equation of exponential increase

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Multi-step chemical and radiation process for the production of gas

International Nuclear Information System (INIS)

O'Neal, R.D.; Leffert, C.B.; Teichmann, T.; Teitel, R.J.

1979-01-01

It has previously been proposed to use the radiation energy within the central reaction chamber of a thermonuclear reactor for the dissociation of water into hydrogen and oxygen in one step. However, the coefficient of recombination of pure hydrogen and oxygen at the elevated reaction chamber temperature is relatively high so that the overall yield is low. Furthermore, it is desirable to recover any unspent tritium from the reaction chamber exhaust, but separation of residual tritium from pure hydrogen in the chamber exhaust is relatively difficult. In the process provided in this patent pure carbon dioxide rather than steam is injected into the central reaction chamber of a thermonuclear reactor. Radiolysis of carbon dioxide yields carbon monoxide and pure oxygen. While the oxygen may be separated and collected at the exhaust vent of the reaction chamber, the carbon monoxide is separated and then combined with water to produce pure hydrogen and reconstituted carbon dioxide, which may be collected and recycled so that the overall closed-loop system produces pure hydrogen and oxygen at the expense of water. The efficiency of the process is high due, in large part, to the relatively low coefficient of recombination of carbon monoxide and oxygen at the reaction chamber temperature. Heat required for the reaction of carbon monoxide with water may be provided by suitable heat transfer from the heated reaction chamber. The chamber exhaust contains carbon monoxide and oxygen, so that any unburnt tritium in the exhaust stream may be easily collected and recycled to form additional pellet fuel. The carbon dioxide molecules injected into the reaction chamber provide protection for the reaction chamber walls from the deleterious effects of charged-particle and x-ray bombardment. (LL)

A step-defined sedentary lifestyle index: <5000 steps/day.

Science.gov (United States)

Tudor-Locke, Catrine; Craig, Cora L; Thyfault, John P; Spence, John C

2013-02-01

Step counting (using pedometers or accelerometers) is widely accepted by researchers, practitioners, and the general public. Given the mounting evidence of the link between low steps/day and time spent in sedentary behaviours, how few steps/day some populations actually perform, and the growing interest in the potentially deleterious effects of excessive sedentary behaviours on health, an emerging question is "How many steps/day are too few?" This review examines the utility, appropriateness, and limitations of using a reoccurring candidate for a step-defined sedentary lifestyle index: 10 000) to lower (sedentary lifestyle index for adults is appropriate for researchers and practitioners and for communicating with the general public. There is little evidence to advocate any specific value indicative of a step-defined sedentary lifestyle index in children and adolescents.

Slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures

Science.gov (United States)

Aines, Roger D.; Bourcier, William L.; Viani, Brian

2013-01-29

A slurried solid media for simultaneous water purification and carbon dioxide removal from gas mixtures includes the steps of dissolving the gas mixture and carbon dioxide in water providing a gas, carbon dioxide, water mixture; adding a porous solid media to the gas, carbon dioxide, water mixture forming a slurry of gas, carbon dioxide, water, and porous solid media; heating the slurry of gas, carbon dioxide, water, and porous solid media producing steam; and cooling the steam to produce purified water and carbon dioxide.

Carbon isotopes in biological carbonates: Respiration and photosynthesis

Science.gov (United States)

McConnaughey, Ted A.; Burdett, Jim; Whelan, Joseph F.; Paull, Charles K.

1997-02-01

Respired carbon dioxide is an important constituent in the carbonates of most air breathing animals but is much less important in the carbonates of most aquatic animals. This difference is illustrated using carbon isotope data from freshwater and terrestrial snails, ahermatypic corals, and chemoautotrophic and methanotrophic pelecypods. Literature data from fish otoliths and bird and mammal shell and bone carbonates are also considered. Environmental CO 2/O 2 ratios appear to be the major controlling variable. Atmospheric CO 2/O 2 ratios are about thirty times lower than in most natural waters, hence air breathing animals absorb less environmental CO 2 in the course of obtaining 0 2. Tissue CO 2 therefore, does not isotopically equilibrate with environmental CO 2 as thoroughly in air breathers as in aquatic animals, and this is reflected in skeletal carbonates. Animals having efficient oxygen transport systems, such as vertebrates, also accumulate more respired CO 2 in their tissues. Photosynthetic corals calcify mainly during the daytime when photosynthetic CO 2 uptake is several times faster than respiratory CO 2 release. Photosynthesis, therefore, affects skeletal δ13C more strongly than does respiration. Corals also illustrate how "metabolic" effects on skeletal isotopic composition can be estimated, despite the presence of much larger "kinetic" isotope effects.

Ecosystem-scale carbon monoxide exchange and partitioning across major biomes in Europe

Science.gov (United States)

Hammerle, Albin; Spielmann, Felix; Kitz, Florian; Ibrom, Andreas; Migliavacca, Mirco; Noe, Steffen; Kolle, Olaf; Moreno, Gerardo; Wohlfahrt, Georg

2017-04-01

With an average mole fraction of 100 ppb carbon monoxide (CO) plays a critical role in atmospheric chemistry and has an indirect global warming potential. While sources/sinks of CO on land at least partially cancel out each other and their magnitude is very likely lower compared to other sinks and sources, the magnitude of CO sources and sinks is highly uncertain. Thus it may be premature to neglect any direct contributions of land ecosystems to the CO budget. In addition, changes in global climate and resulting changes in global productivity may require re-evaluating older data and assumptions. One major reason for the large uncertainty is a general scarcity of empirical data. Here we present data on continuous eddy covariance measurements of CO-fluxes above different biomes in Europe in combination with soil-chamber flux measurements. Eddy covariance and soil-chamber measurements were conducted during the vegetation periods in 2015 and 2016 at a temperate grassland (AUT), a Mediterranean savanna (ESP), a temperate mixed deciduous (DEN) and a hemi-boreal forest (EST). While a clear diel pattern in ecosystem-scale CO-fluxes could be observed at the two grassland sites, with comparatively high emission rates at daytime conditions and fluxes around zero at night, no such pattern could be found for the two forest sites. Soil-chamber measurements mimicked the ecosystem-scale fluxes with CO-emissions during the day at the grassland ecosystems and slightly negative fluxes at night. Applying different treatments the influence of radiation and the availability of litter on these fluxes could be shown. Furthermore, a two-month rainout experiment revealed hardly any differences in CO soil fluxes between rainout- and control-plots at the grassland site (AUT), unless extremely dry conditions were reached.

Screen-printable sol-gel enzyme-containing carbon inks.

Science.gov (United States)

Wang, J; Pamidi, P V; Park, D S

1996-08-01

Enzymes usually cannot withstand the high-temperature curing associated with the thick-film fabrication process and require a separate immobilization step in connection with the production of single-use biosensors. We report on the development of sol-gel-derived enzyme-containing carbon inks that display compatibility with the screen-printing process. Such coupling of sol-gel and thick-film technologies offers a one-step fabrication of disposable enzyme electrodes, as it obviates the need for thermal curing. The enzyme-containing sol-gel carbon ink, prepared by dispersing the biocatalyst, along with the graphite powder and a binder, within the sol-gel precursors, is cured very rapidly (10 min) at low temperature (4 °C). The influence of the ink preparation conditions is explored, and the sensor performance is evaluated in connection with the incorporation of glucose oxidase or horseradish peroxidase. The resulting strips are stable for at least 3 months. Such sol-gel-derived carbon inks should serve as hosts for other heat-sensitive biomaterials in connection with the microfabrication of various thick-film biosensors.

Facile synthesis and application of a carbon foam with large mesopores

KAUST Repository

Fu, Liling

2013-01-01

By combining elements of hard- and soft-templating, a facile synthesis method for carbon foams with large mesopores has been demonstrated. A commercial Pluronic surfactant was used as the structure-directing agent as well as the carbon precursor. No micelle swelling agent or post treatment is necessary to enlarge mesopores. As such this method requires fewer synthesis steps and is highly scalable. The as-synthesized meso-carbons showed potential applications in the fields of carbon oxide capture and lithium-sulfur batteries. © 2013 the Owner Societies.

Biomass pyrolysis liquid to citric acid via 2-step bioconversion.

Science.gov (United States)

Yang, Zhiguang; Bai, Zhihui; Sun, Hongyan; Yu, Zhisheng; Li, Xingxing; Guo, Yifei; Zhang, Hongxun

2014-12-31

The use of fossil carbon sources for fuels and petrochemicals has serious impacts on our environment and is unable to meet the demand in the future. A promising and sustainable alternative is to substitute fossil carbon sources with microbial cell factories converting lignocellulosic biomass into desirable value added products. However, such bioprocesses require tolerance to inhibitory compounds generated during pretreatment of biomass. In this study, the process of sequential two-step bio-conversion of biomass pyrolysis liquid containing levoglucosan (LG) to citric acid without chemical detoxification has been explored, which can greatly improve the utilization efficiency of lignocellulosic biomass. The sequential two-step bio-conversion of corn stover pyrolysis liquid to citric acid has been established. The first step conversion by Phanerochaete chrysosporium (P. chrysosporium) is desirable to decrease the content of other compounds except levoglucosan as a pretreatment for the second conversion. The remaining levoglucosan in solution was further converted into citric acid by Aspergillus niger (A. niger) CBX-209. Thus the conversion of cellulose to citric acid is completed by both pyrolysis and bio-conversion technology. Under experimental conditions, levoglucosan yield is 12% based on the feedstock and the citric acid yield can reach 82.1% based on the levoglucosan content in the pyrolysis liquid (namely 82.1 g of citric acid per 100 g of levoglucosan). The study shows that P. chrysosporium and A. niger have the potential to be used as production platforms for value-added products from pyrolyzed lignocellulosic biomass. Selected P. chrysosporium is able to decrease the content of other compounds except levoglucosan and levoglucosan can be further converted into citric acid in the residual liquids by A. niger. Thus the conversion of cellulose to citric acid is completed by both pyrolysis and bio-conversion technology.

The origins and behaviour of carbon in a major semi-arid river, the Murray River, Australia, as constrained by carbon isotopes and hydrochemistry

Energy Technology Data Exchange (ETDEWEB)

Cartwright, Ian, E-mail: ian.cartwright@monash.edu [School of Geosciences, Monash University, Clayton, Vic. 3800 (Australia)] [National Centre for Groundwater Research and Training, Flinders University, Adelaide SA 5001 (Australia)

2010-11-15

Research highlights: {yields} {delta}{sup 13}C and concentrations of DIC in Murray River controlled by mineralisation of organic carbon and evasion. {yields} Murray River is source of atmospheric CO{sub 2}. {yields} In-river processing of carbon results in difficulties in determining carbon sources. - Abstract: {delta}{sup 13}C values of dissolved inorganic C (DIC), dissolved organic C (DOC), and particulate organic C (POC) together with {delta}{sup 18}O and {delta}{sup 2}H values of water, {delta}{sup 34}S values of dissolved SO{sub 4}, and major ion concentrations were measured in the Murray River and its tributaries between November 2005 and April 2007 to constrain the origins and behaviour of riverine C. {delta}{sup 13}C{sub DIC} values in the Murray River vary between -9.5 and -4.7 per mille with a range of <3 per mille within any sampling round. {delta}{sup 13}C{sub DIC} values of the tributaries are -11.0 per mille to -5.1 per mille. DIC concentrations of the Murray River increase from {approx}25 mg/L in the middle and upper reaches of the river to 45-55 mg/L in the lower reaches. However, the mass ratio of DIC as a proportion of the total dissolved solids (TDS) decreases from {approx}0.6-0.7 in the headwaters to {approx}0.2-0.3 in the lower reaches of the river, with similar downstream changes in DIC/Cl ratios. This precludes simple evaporative concentration of DIC and is interpreted as the river evading CO{sub 2}; this interpretation is consistent with pCO{sub 2} values that are in the range 550-11,200 ppm volume (ppmv), which are far higher than those in equilibrium with the atmosphere ({approx}360 ppmv). The {delta}{sup 13}C{sub DIC} values are similar to those that would be produced by the weathering of marine limestone ({delta}{sup 13}C {approx} 0 per mille). However, the lack of marine limestones cropping out in the Murray-Darling Basin and the relatively uniform {delta}{sup 13}C{sub DIC} values of the Murray River (even in upland reaches where the

Kinetic Modeling of the Reaction Rate for Quartz and Carbon Pellet

Science.gov (United States)

Li, Fei; Tangstad, Merete

2018-04-01

Kinetic modeling of quartz and carbon pellet at temperatures of 1898 K, 1923 K, and 1948 K (1625 °C, 1650 °C, and 1675 °C) was investigated in this study. The carbon materials used were charcoal, coke, coal, and preheated coal. The overall SiC producing reaction can be described by the reaction SiO2 + 3C = SiC + 2CO. In the SiC-producing step, the reaction rate of quartz and carbon pellet can be expressed as {d{ pct}}/dt = ( {1 - 0.40 × X_{fix - C}^{ - 0.86} × FC × {pct}} ) × A × \\exp ( { - E/{{RT}}} ) The carbon factor F C was used to describe the influence of different carbon materials that effect the gas-solid interface reaction. For charcoal, coke, coal, and preheated coal, the F C values were 0.83, 0.80, 0.94, and 0.83, respectively. The pre-exponential factor A values for the preceding four carbon materials were 1.06 × 1016 min-1, 4.21 × 1015 min-1, 3.85 × 109 min-1, and 1.00 × 1025 min-1, respectively. The activation energies E for the SiC-producing step were 570, 563, 336, and 913 kJ/mole for charcoal, coke, coal, and preheated coal pellets, respectively.

A Step towards Sustainable Society: The Awareness of Carbon Dioxide Emissions, Climate Change and Carbon Capture in Malaysia

OpenAIRE

Ghazali, Zulkipli; Zahid, Muhammad; Kee, Tan Siok; Ibrahim, M. Yussoff

2016-01-01

Public awareness is crucial to mitigate negative impacts on the environment. The aim of the study is to explore the level of public awareness in five states of Malaysia (Perak, Melaka, Johor, Pahang and Terengganu) regarding CO2 emissions, climate change and carbon capture and storage (CCS). A questionnaire floated for exploring public awareness regarding CO2 emissions, climate change and CCS. Based on the questionnaire data was collected from five states (Perak, Melaka, Johor, Pahang and Ter...

Astronomical sketching a step-by-step introduction

CERN Document Server

Handy, Richard; Perez, Jeremy; Rix, Erika; Robbins, Sol

2007-01-01

This book presents the amateur with fine examples of astronomical sketches and step-by-step tutorials in each medium, from pencil to computer graphics programs. This unique book can teach almost anyone to create beautiful sketches of celestial objects.

Forestry in a greenhouse climate: For wood production or carbon storage?

International Nuclear Information System (INIS)

Pollard, D.F.W.

1991-01-01

The forest sector is one of the major sources of carbon dioxide in British Columbia, from pulp and papr processing and prescribed burning. To enhance knowledge about carbon budgets, Forestry Canada has developed a simulation model of the carbon pools and fluxes in the Canadian forest sector, which clearly indicates that the boreal forest, with its soils, is a major carbon pool, and also a major source of carbon, from combustion of biomass and soil organic matter. Outside the subarctic, forest growth more than compensates for fire losses in most years, and the forest is therefore calculated to be a net accumulator of carbon. While the conversion of old growth forest to managed stands on shorter rotations reduces stored carbon averaged over space and time, there is potential for managed forests to increase average live biomass, through genetic and silvicultural enhancement and through protection. A serious possibility of positive feedback by forests to the climatic warming exists in peatlands currently subject to permafrost. A warming could lead to substantial emissions of methane and carbon dioxide from vast areas. 14 refs

Comparison between two methods of methanol production from carbon dioxide

International Nuclear Information System (INIS)

Anicic, B.; Trop, P.; Goricanec, D.

2014-01-01

Over recent years there has been a significant increase in the amount of technology contributing to lower emissions of carbon dioxide. The aim of this paper is to provide a comparison between two technologies for methanol production, both of which use carbon dioxide and hydrogen as initial raw materials. The first methanol production technology includes direct synthesis of methanol from CO 2 , and the second has two steps. During the first step CO 2 is converted into CO via RWGS (reverse water gas shift) reaction, and methanol is produced during the second step. A comparison between these two methods was achieved in terms of economical and energy-efficiency bases. The price of electricity had the greatest impact from the economical point of view as hydrogen is produced via the electrolysis of water. Furthermore, both the cost of CO 2 capture and the amounts of carbon taxes were taken into consideration. Energy-efficiency comparison is based on cold gas efficiency, while economic feasibility is compared using net present value. Even though the mentioned processes are similar, it was shown that direct methanol synthesis has higher energy and economic efficiency. - Highlights: • We compared two methods for methanol production. • Process schemes for both, direct synthesis and two-step synthesis, are described. • Direct synthesis has higher economical and energy efficiency

Carbon isotopes and concentrations in mid-oceanic ridge basalts

International Nuclear Information System (INIS)

Pineau, F.; Javoy, M.

1983-01-01

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

The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration

Directory of Open Access Journals (Sweden)

Fulvio Di Lorenzo

2018-05-01

Full Text Available One of the most promising strategies for the safe and permanent disposal of anthropogenic CO2 is its conversion into carbonate minerals via the carbonation of calcium and magnesium silicates. However, the mechanism of such a reaction is not well constrained, and its slow kinetics is a handicap for the implementation of silicate mineral carbonation as an effective method for CO2 capture and storage (CCS. Here, we studied the different steps of wollastonite (CaSiO3 carbonation (silicate dissolution → carbonate precipitation as a model CCS system for the screening of natural and biomimetic catalysts for this reaction. Tested catalysts included carbonic anhydrase (CA, a natural enzyme that catalyzes the reversible hydration of CO2(aq, and biomimetic metal-organic frameworks (MOFs. Our results show that dissolution is the rate-limiting step for wollastonite carbonation. The overall reaction progresses anisotropically along different [hkl] directions via a pseudomorphic interface-coupled dissolution–precipitation mechanism, leading to partial passivation via secondary surface precipitation of amorphous silica and calcite, which in both cases is anisotropic (i.e., (hkl-specific. CA accelerates the final carbonate precipitation step but hinders the overall carbonation of wollastonite. Remarkably, one of the tested Zr-based MOFs accelerates the dissolution of the silicate. The use of MOFs for enhanced silicate dissolution alone or in combination with other natural or biomimetic catalysts for accelerated carbonation could represent a potentially effective strategy for enhanced mineral CCS.

Process for obtaining ammonium uranyl tri carbonate

International Nuclear Information System (INIS)

Santos, L.R. dos; Riella, H.G.

1992-01-01

The procedure adopted for obtaining Ammonium Uranyl Carbonate (AUC) from uranium hexafluoride (U F 6 ) in a aqueous solutions of ammonium hydrogen carbonate is described in this work. The precipitation is made in temperature and pH controlled. This process consists of three steps: evaporation of U F 6 , AUC precipitation and filtration of the AUC slurry. An attempt is made of correlate the parameters involved in the precipitation process of AUC with its and U O 2 characteristics. (author)

Azide photochemistry for facile modification of graphitic surfaces: preparation of DNA-coated carbon nanotubes for biosensing

International Nuclear Information System (INIS)

Moghaddam, Minoo J; Yang Wenrong; Bojarski, Barbara; Gengenbach, Thomas R; Gao Mei; Zareie, Hadi; McCall, Maxine J

2012-01-01

A facile, two-step method for chemically attaching single-stranded DNA to graphitic surfaces, represented here by carbon nanotubes, is reported. In the first step, an azide-containing compound, N-5-azido-nitrobenzoyloxy succinimide (ANB-NOS), is used to form photo-adducts on the graphitic surfaces in a solid-state photochemical reaction, resulting in active ester groups being oriented for the subsequent reactions. In the second step, pre-synthesized DNA strands bearing a terminal amine group are coupled in an aqueous solution with the active esters on the photo-adducts. The versatility of the method is demonstrated by attaching pre-synthesized DNA to surfaces of carbon nanotubes in two platforms—as vertically-aligned multi-walled carbon nanotubes on a solid support and as tangled single-walled carbon nanotubes in mats. The reaction products at various stages were characterized by x-ray photoelectron spectroscopy. Two different assays were used to check that the DNA strands attached to the carbon nanotubes were able to bind their partner strands with complementary base sequences. The first assay, using partner DNA strands tethered to gold nanoparticles, enabled the sites of DNA attachment to the carbon nanotubes to be identified in TEM images. The second assay, using radioactively labelled partner DNA strands, quantified the density of functional DNA strands attached to the carbon nanotubes. The diversity of potential applications for these DNA-modified carbon-nanotube platforms is exemplified here by the successful use of a DNA-modified single-walled carbon-nanotube mat as an electrode for the specific detection of metal ions. (paper)

Looking Forward. The Carbon Markets

International Nuclear Information System (INIS)

Wilder, M.

2006-02-01

An overview is given of possible future developments in the market for carbon dioxide emissions trading. In this presentation it is concluded that the carbon market is here and now, that the carbon market is global and China and India are major players, that global capital is on the move and delay is dangerous, that there is a world of opportunity for Australian companies and with inaction there is a risk to fall off the fringe

One step beyond: Different step-to-step transitions exist during continuous contact brachiation in siamangs

Directory of Open Access Journals (Sweden)

Fana Michilsens

2012-02-01

In brachiation, two main gaits are distinguished, ricochetal brachiation and continuous contact brachiation. During ricochetal brachiation, a flight phase exists and the body centre of mass (bCOM describes a parabolic trajectory. For continuous contact brachiation, where at least one hand is always in contact with the substrate, we showed in an earlier paper that four step-to-step transition types occur. We referred to these as a ‘point’, a ‘loop’, a ‘backward pendulum’ and a ‘parabolic’ transition. Only the first two transition types have previously been mentioned in the existing literature on gibbon brachiation. In the current study, we used three-dimensional video and force analysis to describe and characterize these four step-to-step transition types. Results show that, although individual preference occurs, the brachiation strides characterized by each transition type are mainly associated with speed. Yet, these four transitions seem to form a continuum rather than four distinct types. Energy recovery and collision fraction are used as estimators of mechanical efficiency of brachiation and, remarkably, these parameters do not differ between strides with different transition types. All strides show high energy recoveries (mean  = 70±11.4% and low collision fractions (mean  = 0.2±0.13, regardless of the step-to-step transition type used. We conclude that siamangs have efficient means of modifying locomotor speed during continuous contact brachiation by choosing particular step-to-step transition types, which all minimize collision fraction and enhance energy recovery.

Pt coating on flame-generated carbon particles

International Nuclear Information System (INIS)

Choi, In Dae; Lee, Dong Geun

2008-01-01

Carbon black, activated carbon and carbon nanotube have been used as supporting materials for precious metal catalysts used in fuel cell electrodes. One-step flame synthesis method is used to coat 2-5nm Pt dots on flame-generated carbon particles. By adjusting flame temperature, gas flow rates and resident time of particles in flame, we can obtain Pt/C nano catalyst-support composite particles. Additional injection of hydrogen gas facilitates pyrolysis of Pt precursor in flame. The size of as-incepted Pt dots increases along the flame due to longer resident time and sintering in high temperature flame. Surface coverage and dispersion of the Pt dots is varied at different sampling heights and confirmed by Transmission Electron Microscopy (TEM), Energy Dispersive Spectra (EDS) and X-Ray Diffraction (XRD). Crystallinity and surface bonding groups of carbon are investigated through X-ray Photoelectron Spectroscoy (XPS) and Raman spectroscopy

A stepped strategy that aims at the nationwide implementation of the Enhanced Recovery After Surgery programme in major gynaecological surgery: study protocol of a cluster randomised controlled trial.

Science.gov (United States)

de Groot, Jeanny Ja; Maessen, José Mc; Slangen, Brigitte Fm; Winkens, Bjorn; Dirksen, Carmen D; van der Weijden, Trudy

2015-07-30

Enhanced Recovery After Surgery (ERAS) programmes aim at an early recovery after surgical trauma and consequently at a reduced length of hospitalisation. This paper presents the protocol for a study that focuses on large-scale implementation of the ERAS programme in major gynaecological surgery in the Netherlands. The trial will evaluate effectiveness and costs of a stepped implementation approach that is characterised by tailoring the intensity of implementation activities to the needs of organisations and local barriers for change, in comparison with the generic breakthrough strategy that is usually applied in large-scale improvement projects in the Netherlands. All Dutch hospitals authorised to perform major abdominal surgery in gynaecological oncology patients are eligible for inclusion in this cluster randomised controlled trial. The hospitals that already fully implemented the ERAS programme in their local perioperative management or those who predominantly admit gynaecological surgery patients to an external hospital replacement care facility will be excluded. Cluster randomisation will be applied at the hospital level and will be stratified based on tertiary status. Hospitals will be randomly assigned to the stepped implementation strategy or the breakthrough strategy. The control group will receive the traditional breakthrough strategy with three educational sessions and the use of plan-do-study-act cycles for planning and executing local improvement activities. The intervention group will receive an innovative stepped strategy comprising four levels of intensity of support. Implementation starts with generic low-cost activities and may build up to the highest level of tailored and labour-intensive activities. The decision for a stepwise increase in intensive support will be based on the success of implementation so far. Both implementation strategies will be completed within 1 year and evaluated on effect, process, and cost-effectiveness. The primary

Application of stepping motor

International Nuclear Information System (INIS)

1980-10-01

This book is divided into three parts, which is about practical using of stepping motor. The first part has six chapters. The contents of the first part are about stepping motor, classification of stepping motor, basic theory og stepping motor, characteristic and basic words, types and characteristic of stepping motor in hybrid type and basic control of stepping motor. The second part deals with application of stepping motor with hardware of stepping motor control, stepping motor control by microcomputer and software of stepping motor control. The last part mentions choice of stepping motor system, examples of stepping motor, measurement of stepping motor and practical cases of application of stepping motor.

Carbon Dioxide for pH Control

Energy Technology Data Exchange (ETDEWEB)

Wagonner, R.C.

2001-08-16

Cardox, the major supplier of carbon dioxide, has developed a diffuser to introduce carbon dioxide into a water volume as small bubbles to minimize reagent loss to the atmosphere. This unit is integral to several configurations suggested for treatment to control alkalinity in water streams.

Internship guide : Work placements step by step

NARCIS (Netherlands)

Haag, Esther

2013-01-01

Internship Guide: Work Placements Step by Step has been written from the practical perspective of a placement coordinator. This book addresses the following questions : what problems do students encounter when they start thinking about the jobs their degree programme prepares them for? How do you

Production of activated carbon from TCR char

Science.gov (United States)

Stenzel, Fabian; Heberlein, Markus; Klinner, Tobias; Hornung, Andreas

2016-04-01

The utilization of char for adsorptive purposes is known since the 18th century. At that time the char was made of wood or bones and used for decoloration of fluids. In the 20th century the production of activated carbon in an industrial scale was started. The today's raw materials for activated carbon production are hard coal, peat, wood or coconut shells. All these materials entail costs especially the latter. Thus, the utilization of carbon rich residues (biomass) is an interesting economic opportunity because it is available for no costs or even can create income. The char is produced by thermo-catalytic reforming (TCR®). This process is a combination of an intermediate pyrolysis and subsequently a reforming step. During the pyrolysis step the material is decomposed in a vapor and a solid carbon enriched phase. In the second step the vapor and the solid phase get in an intensive contact and the quality of both materials is improved via the reforming process. Subsequently, the condensables are precipitated from the vapor phase and a permanent gas as well as oil is obtained. Both are suitable for heat and power production which is a clear advantage of the TCR® process. The obtained biochar from the TCR® process has special properties. This material has a very low hydrogen and oxygen content. Its stability is comparable to hard coal or anthracite. Therefore it consists almost only of carbon and ash. The latter depends from input material. Furthermore the surface structure and area can be influenced during the reforming step. Depending from temperature and residence time the number of micro pores and the surface area can be increased. Preliminary investigations with methylene blue solution have shown that a TCR® char made of digestate from anaerobic digestion has adsorptive properties. The decoloration of the solution was achieved. A further influencing factor of the adsorption performance is the particle size. Based on the results of the preliminary tests a

Microsoft Office professional 2010 step by step

CERN Document Server

Cox, Joyce; Frye, Curtis

2011-01-01

Teach yourself exactly what you need to know about using Office Professional 2010-one step at a time! With STEP BY STEP, you build and practice new skills hands-on, at your own pace. Covering Microsoft Word, PowerPoint, Outlook, Excel, Access, Publisher, and OneNote, this book will help you learn the core features and capabilities needed to: Create attractive documents, publications, and spreadsheetsManage your e-mail, calendar, meetings, and communicationsPut your business data to workDevelop and deliver great presentationsOrganize your ideas and notes in one placeConnect, share, and accom

7 CFR 3052.520 - Major program determination.

Science.gov (United States)

2010-01-01

... Auditors § 3052.520 Major program determination. (a) General. The auditor shall use a risk-based approach... section shall be followed. (b) Step 1. (1) The auditor shall identify the larger Federal programs, which... providing loans significantly affects the number or size of Type A programs, the auditor shall consider this...

Biomineralization and the carbon isotope record

International Nuclear Information System (INIS)

Degens, E.T.; Ittekkot, V.; Kazmierczak, J.

1986-01-01

The advent of biomineralization at the turn of the Precambrian/Cambrian boundary has been a major event in the Earth's evolutionary history. With this there has been a major shift from abiotic to biotic formation of minerals such as phosphates and carbonates and, subsequently, silica. The dominant factor which effected this shift is a change in ocean's chemistry with respect to its Ca 2+ and mineral nutrient contents. Mechanism controlling the biotic mineral formation is different from that controlling the abiotic one in that the former is enzymically controlled. It is suggested that this difference is also manifested in the stable carbon isotope fractionation between the two processes and has implication for the interpretation of stable carbon isotope record. (Author)

Black carbon: The reverse of its dark side

NARCIS (Netherlands)

Koelmans, A.A.; Jonker, M.T.O.; Cornelissen, G.; Bucheli, T.D.; Noort, van P.C.M.; Gustafsson, O.

2006-01-01

The emission of black carbon is known to cause major environmental problems. Black carbon particles contribute to global warming, carry carcinogenic compounds and cause serious health risks. Here, we show another side of the coin. We review evidence that black carbon may strongly reduce the risk

Ab-initio perturbed-cluster study of carbon monoxide adsorption at a stepped LiF(001) surface

Science.gov (United States)

Pisani, C.; Corà, F.; Orlando, R.; Nada, R.

1993-02-01

The perturbed-cluster ab-initio Hartree-Fock approach to the study of local defects in crystals [J. Chem. Phys. 92(1990)7448] is applied to the study of CO adsorption at a stepped LiF(001) surface. The step is simulated by a tablet of four ions superimposed on an infinite LiF(001) monolayer. The geometry of the step is first optimized, and corresponds to an important relaxation of cations and anions of the tablet inwards and outwards, respectively. The equilibrium configuration, adsorption energy and vibrational frequency of CO at a corner of the tablet occupied by a lithium cation are calculated. With respect to adsorption at a perfect (100) face, there is a large increase in interaction energy, especially when adsorption occurs via the oxygen atom. This difference is essentially related to modifications of the electrostatic field experienced by the adsorbed molecule.

A study on the nondestructive evaluation of carbon/carbon disk using ultrasonics

International Nuclear Information System (INIS)

Im, Kwang Hee; Yang, In Young; Jeong, Hyun Jo

1998-01-01

It is useful to perform nondestructive evaluation (NDE) to assess material properties and part homogeneity for carbon/carbon (C/C) composites because the manufacturing of C/C brake disks requires complicated and costly processes. In this work several ultrasonic techniques were applied to attributable to the manufacturing process. In a carbon/carbon brake disk manufactured by a combination of pitch impregnation and CVI(Vapor infiltration method), the spatial variation of ultrasonic velocity was measured and found to be consistent with the nonuniform densification behavior in the manufacturing process. Low frequency(5 MHz) through-transmission scans based on both amplitude and time-of-flight of the ultrasonic pulse were used for mapping out the material property inhomogeneity. These results were compared with those obtained by dry-coupling ultrasonics. A good correlation was found between ultrasonic velocity and material density on a set of small blocks cut out of the disk. Pulse-echo C-scans at higher frequency (25 MHz) were used to image near-sulfate material property anomalies associated with certain steps in the manufacturing process, such as the placement of spacers between disks during the final CVI.

A facile one-step approach for the fabrication of polypyrrole nanowire/carbon fiber hybrid electrodes for flexible high performance solid-state supercapacitors

Science.gov (United States)

Huang, Sanqing; Han, Yichuan; Lyu, Siwei; Lin, Wenzhen; Chen, Peishan; Fang, Shaoli

2017-10-01

Wearable electronics are in high demand, requiring that all the components are flexible. Here we report a facile approach for the fabrication of flexible polypyrrole nanowire (NPPy)/carbon fiber (CF) hybrid electrodes with high electrochemical activity using a low-cost, one-step electrodeposition method. The structure of the NPPy/CF electrodes can be easily controlled by the applied electrical potential and electrodeposition time. Our NPPy/CF-based electrodes showed high flexibility, conductivity, and stability, making them ideal for flexible all-solid-state fiber supercapacitors. The resulting NPPy/CF-based supercapacitors provided a high specific capacitance of 148.4 F g-1 at 0.128 A g-1, which is much higher than for supercapacitors based on polypyrrole film/CF (38.3 F g-1) and pure CF (0.6 F g-1) under the same conditions. The NPPy/CF-based supercapacitors also showed high bending and cycling stability, retaining 84% of the initial capacitance after 500 bending cycles, and 91% of the initial capacitance after 5000 charge/discharge cycles.

A facile one-step approach for the fabrication of polypyrrole nanowire/carbon fiber hybrid electrodes for flexible high performance solid-state supercapacitors.

Science.gov (United States)

Huang, Sanqing; Han, Yichuan; Lyu, Siwei; Lin, Wenzhen; Chen, Peishan; Fang, Shaoli

2017-10-27

Wearable electronics are in high demand, requiring that all the components are flexible. Here we report a facile approach for the fabrication of flexible polypyrrole nanowire (NPPy)/carbon fiber (CF) hybrid electrodes with high electrochemical activity using a low-cost, one-step electrodeposition method. The structure of the NPPy/CF electrodes can be easily controlled by the applied electrical potential and electrodeposition time. Our NPPy/CF-based electrodes showed high flexibility, conductivity, and stability, making them ideal for flexible all-solid-state fiber supercapacitors. The resulting NPPy/CF-based supercapacitors provided a high specific capacitance of 148.4 F g -1 at 0.128 A g -1 , which is much higher than for supercapacitors based on polypyrrole film/CF (38.3 F g -1 ) and pure CF (0.6 F g -1 ) under the same conditions. The NPPy/CF-based supercapacitors also showed high bending and cycling stability, retaining 84% of the initial capacitance after 500 bending cycles, and 91% of the initial capacitance after 5000 charge/discharge cycles.

Increased topsoil carbon stock across China's forests.

Science.gov (United States)

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

2014-08-01

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

Improved field emission properties of thiolated multi-wall carbon nanotubes on a flexible carbon cloth substrate

International Nuclear Information System (INIS)

Chuang, F T; Chen, P Y; Cheng, T C; Chien, C H; Li, B J

2007-01-01

In this paper we report the observation of enhanced field emission properties from thiolated multi-wall carbon nanotubes (MWCNTs) produced by a simple and effective two-step chemical surface modification technique. This technique implements carboxylation and thiolation on the MWCNTs synthesized by microwave plasma chemical vapor deposition (MPCVD) on the flexible carbon cloth substrate. The resulting thiolated MWCNTs were found to have a very low threshold field value of 1.25 V μm -1 and a rather high field enhancement factor of 1.93 x 10 4 , which are crucial for applications in versatile vacuum microelectronics

A survey of the Carbon Capture

International Nuclear Information System (INIS)

Jokrllova, J.; Cik, G.; Takacova, A.; Smolinska, M.

2014-01-01

The concentration of carbon dioxide, one of the most important representatives of greenhouse gases in the atmosphere continues to rise. Fossil fuels burned in thermal power plants currently represent 80% of total energy production around the world and are the largest point sources of CO 2 , accounting for approximately 40% of total CO 2 emissions. There are several options for reducing CO 2 emissions: reducing demand, improving production efficiency and carbon capture and storage (CCS, carbon capture and storage). Capture and storage of carbon dioxide is generally a three-step process: 1 st Capture and compression of combustion products, 2 nd transport (mostly pipeline) and 3 rd utilization (eg. production of urea, beverage industry, production of dry ice, etc.). Technologies for CO 2 capturing used in power plants burning fossil fuels can be divided into four groups, each of which requires a completely different approach to CO 2 capture.

Is carbon farming an effective climate mitigation option?

Science.gov (United States)

Zelikova, T. J.; Funk, J.; Deich, N.; Amador, G.; Jacobson, R.

2017-12-01

"Carbon farming" refers to agricultural and land management practices that store carbon in soils and biomass. Carbon-farming techniques can include crop rotation, cover crops, no-till practices, and the application of compost to build up soil organic matter. Carbon farming also improves agricultural production and sustainability, while mitigating climate change. Despite well-documented benefits of carbon farming, these practices continue to be underutilized outside of experimental settings. One barrier to the widespread use of carbon farming is the challenge of fitting these practices into ongoing commercial operations, while managing the consequent market uncertainties across the value chain. To help address this barrier, we are working with landowners and local groups to establish demonstration "test beds" that can build experience among land managers and help resolve market uncertainties. We specifically focus on demonstrating the commercial viability of management practices that can enhance soil health, catalyzing economic and environmental synergies that come from healthy soils. Each test bed has a commercial agricultural operation at its center, and we bring together researchers, local groups, corporate partners, and key policymakers who can support wider adoption of these agricultural techniques. Early challenges have included finding commercial farms willing to shift their practices and face uncertain outcomes. A transition to new practices usually involves changes in equipment, scheduling, activities, and monitoring that have implications for the entire farm operation, its resources, and its bottom line. At the same time, practitioners have difficulty quantifying the carbon benefits they provide, due to persistent uncertainties, even with the benefit of decades of experimental research. We are building a network of farmers who are implementing carbon farming practices and addressing these challenges, step by step. We envision our test beds becoming hubs

High resolution carbon isotope of Crassostrea cuttakensis: A proxy for seasonally varying carbon dynamics in a tropical delta-estuary system

Science.gov (United States)

Sreemany, Arpita

2017-04-01

The exponential increase in the atmospheric CO2 concentration and global temperature is becoming a major threat to the existence of the mankind. It has been proposed that the ˜2 ˚ C rise in the average global temperature may lead to a point of no-return where the balance between the climate and the ecosystem collapses. Therefore, detailed understanding of the major carbon reservoirs and their mutual interactions is needed for better future climate prediction. Among all the reservoirs, ocean holds ˜90 % of the exogenic carbon and promotes long term storage in sediments. However, the majority of the sedimentary carbon is of terrestrial origin and transported through rivers, which play an important role in carbon exchange between the atmosphere, terrestrial biosphere, and oceans. The transportation of organic carbon through river does not follow a simple conveyer belt model. Various organic and inorganic reactions (i.e., organic carbon degradation, inorganic carbon precipitation, primary production, community respiration) modify the state of the carbon to form a major sub-reservoir in the river, i.e., Dissolved Inorganic Carbon (DIC). So, identifying the source/s of the DIC is crucial to understand the carbon dynamics in the river. Stable carbon isotopic composition of the DIC (δ13CDIC) has long been extensively used to reveal the dominant source/s of the DIC. The majority of the large rivers, being situated in the tropical belts, show seasonal fluctuation in the DIC sources. However, seasonal sampling in the remotest reaches of these rivers hindered our thorough understanding of the seasonally varying source/s of DIC in these rivers. Many calcifying organisms precipitate their shell carbonate in equilibrium with water and hence likely to record the δ13CDICof ambient water in their shell. In this study, a living oyster (Crassostrea cuttakensis) was collected from Matla River, which is part of the Ganges Brahmaputra river delta system, and analyzed for its stable

Doubling the number of physics majors who teach

Science.gov (United States)

Marder, Michael

2009-03-01

The American Physical Society has adopted a doubling initiative to increase the number of physics majors. One of the main motivations is to increase the number of physics majors certified to teach secondary physics. I will review some of the possible strategies for reaching this goal, and discuss some of the steps we have taken with UTeach, the program for secondary science and mathematics teacher preparation at The University of Texas at Austin.I will discuss the roles of curriculum revision, financial support, and community support in convincing majors to teach. Finally, I will talk about the expansion of UTeach into engineering.

Carbon profiles of remote Australian Indigenous communities: A base for opportunities

International Nuclear Information System (INIS)

Stewart, J.; Anda, M.; Harper, R.J.

2016-01-01

A decision-making model was constructed to assist remote Australian Indigenous communities select appropriate climate change mitigation programs. The Resilient Community and Livelihood Asset Integration Model (ReCLAIM) comprises six steps that focus on community assets and aspirations. The second of these steps is to determine the baseline carbon profiles of communities based on six sources of carbon emissions: materials, construction processes, stationary energy, transport, water systems and waste. The methodology employed an annualised lifecycle analysis of housing materials and construction, and an annual inventory of other emission sources. Profiles were calculated for two remote communities and compared to the Australian average and also average electricity consumption by remote communities in the Northern Territory. The results, expressed in tonnes of carbon dioxide equivalent (tCO_2-e), showed that average household carbon profiles of the two communities (6.3 and 4.1 tCO_2-e/capita/yr) were generally lower than the Australian average (7.3 tCO_2-e/capita/yr). The stationary energy results revealed that infrastructure and building design could raise fuel consumption and costs, and therefore carbon emissions, despite modest lifestyles. The carbon emission categories differed between the two communities highlighting the need for an individualised approach to understanding the drivers of carbon emissions and mitigation responses. - Highlights: •We model carbon profiles of two remote Aboriginal communities. •Community carbon profiles were lower than the Australian average. •We compare stationary energy with a 72-community sample average. •Low-carbon communities are possible with renewable energy systems. •Building design and energy source can impact significantly on emissions.

Controllable Synthesis of Functional Hollow Carbon Nanostructures with Dopamine As Precursor for Supercapacitors.

Science.gov (United States)

Liu, Chao; Wang, Jing; Li, Jiansheng; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

2015-08-26

N-doped hollow carbon spheres (N-HCSs) are promising candidates as electrode material for supercapacitor application. In this work, we report a facile one-step synthesis of discrete and highly dispersible N-HCSs with dopamine (DA) as a carbon precursor and TEOS as a structure-assistant agent in a mixture containing water, ethanol, and ammonia. The architectures of resultant N-HCSs, including yolk-shell hollow carbon spheres (YS-HCSs), single-shell hollow carbon spheres (SS-HCSs), and double-shells hollow carbon spheres (DS-HCSs), can be efficiently controlled through the adjustment of the amount of ammonia. To explain the relation and formation mechanism of these hollow carbon structures, the samples during the different synthetic steps, including polymer/silica spheres, carbon/silica spheres and silica spheres by combustion in air, were characterized by TEM. Electrochemical measurements performed on YS-HCSs, SS-HCSs, and DS-HCSs showed high capacitance with 215, 280, and 381 F g(-1), respectively. Moreover, all the nitrogen-doped hollow carbon nanospheres showed a good cycling stability 97.0% capacitive retention after 3000 cycles. Notably, the highest capacitance of DS-HCSs up to 381 F g(-1) is higher than the capacitance reported so far for many carbon-based materials, which may be attributed to the high surface area, hollow structure, nitrogen functionalization, and double-shell architecture. These kinds of N-doped hollow-structured carbon spheres may show promising prospects as advanced energy storage materials and catalyst supports.

Progress in the reduction of carbon monoxide levels in major urban areas in Korea

International Nuclear Information System (INIS)

Kim, Ki-Hyun; Sul, Kyung-Hwa; Szulejko, Jan E.; Chambers, Scott D.; Feng, Xinbin; Lee, Min-Hee

2015-01-01

Long-term trends in observed carbon monoxide (CO) concentrations were analyzed in seven major South Korean cities from 1989 to 2013. Temporal trends were evident on seasonal and annual timescales, as were spatial gradients between the cities. As CO levels in the most polluted cities decreased significantly until the early 2000s, the data were arbitrarily divided into two time periods (I: 1989–2000 and II: 2001–2013) for analysis. The mean CO concentration of period II was about 50% lower than that of period I. Long-term trends of annual mean CO concentrations, examined using the Mann–Kendall (MK) method, confirm a consistent reduction in CO levels from 1989 to 2000 (period I). The abrupt reduction in CO levels was attributed to a combination of technological improvements and government administrative/regulatory initiatives (e.g., emission mitigation strategies and a gradual shift in the fuel/energy consumption mix away from coal and oil to natural gas and nuclear power). - Highlights: • As one of the criteria pollutants, CO has been extensively studied worldwide. • The concentration of CO in ambient air should be reduced to a more manageable level. • The spatiotemporal characteristics of CO in Korea are analyzed for 1989–2013. • Our efforts will help develop systematic strategies to reduce CO emissions. - The efficacy of CO mitigation strategies adopted throughout Korea is highlighted along with the limitations faced to improving air quality due to cross-boundary pollution transport.

Electrophoretic deposition (EPD) of multi-walled carbon nano tubes (MWCNT) onto indium-tin-oxide (ITO) glass substrates

International Nuclear Information System (INIS)

Mohd Roslie Ali; Shahrul Nizam Mohd Salleh

2009-01-01

Full text: Multi-Walled Carbon Nano tubes (MWCNT) were deposited onto Indium-Tin-Oxide (ITO)-coated glass substrates by introducing the use of Electrophoretic Deposition (EPD) as the method. The Multi-Walled Carbon Nano tubes (MWCNT) were dispersed ultrasonically in ethanol and sodium hydroxide (NaOH) to form stable suspension. The addition of Sodium Hydroxide in ethanol can stabilize the suspension, which was very important step before the deposition take place. Two substrates of Indium-Tin-Oxide(ITO)-coated glass placed in parallel facing each other (conductive side) into the suspension. The deposition occurs at room temperature, which the distance fixed at 1 cm between both electrodes and the voltage level applied was fixed at 400 V, respectively. The deposition time also was fixed at 30 minutes. The deposited ITO-Glass with Multi-Walled Carbon Nano tubes (MWCNT) will be characterized using Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM), and Raman Microscope. The images of SEM shows that the Multi -Walled Carbon Nano tubes (MWCNT) were distributed uniformly onto the surface of ITO-Glass. The deposited ITO-Glass with Multi-Walled Carbon Nano tubes (MWCNT) could be the potential material in various practical applications such as field emission devices, fuel cells, and super capacitors. Electrophoretic deposition (EPD) technique was found to be an efficient technique in forming well distribution of Multi-Walled Carbon Nano tubes (MWCNT) onto ITO-Glass substrates, as proved in characterization methods, in which the optimum conditions will play the major role. (author)

29 CFR 99.520 - Major program determination.

Science.gov (United States)

2010-07-01

... Auditors § 99.520 Major program determination. (a) General. The auditor shall use a risk-based approach to... followed. (b) Step 1. (1) The auditor shall identify the larger Federal programs, which shall be labeled... size of Type A programs, the auditor shall consider this Federal program as a Type A program and...

Structure–mechanical property relationship in a high strength low carbon alloy steel processed by two-step intercritical annealing and intercritical tempering

International Nuclear Information System (INIS)

Zhou, W.H.; Wang, X.L.; Venkatsurya, P.K.C.; Guo, H.; Shang, C.J.; Misra, R.D.K.

2014-01-01

The influence of annealing and tempering temperature on the microstructure and mechanical properties was investigated in a low carbon alloy steel that was processed by a two-step intercritical annealing and intercritical tempering heat treatment. In general, the microstructure of the processed steel comprises intercritical lath-like ferrite, bainitic/martensitic lath and acicular-type retained austenite. The lower intercritical annealing temperature resulted in lower fraction of intercritical ferrite with finer grain size and consequently higher strength. On the other hand, the intercritical tempering temperature significantly influenced retained austenite content and precipitation. High fraction of retained austenite was obtained at a temperature slightly above Ac 1 temperature and retained austenite content decreased with increase in tempering temperature. This behavior is attributed to the competition between the enrichment of Mn and Ni and the fraction of reversed austenite. Fine niobium carbide precipitates of size ∼2–6 nm and copper precipitates of size range ∼10–30 nm were obtained. The optimal intercritical annealing and tempering temperatures to obtain the product of tensile strength and elongation % of ∼30 GPa% were 780 °C and 660 °C, respectively and the volume fraction of retained austenite was ∼29%

One-step synthesis of N-doped activated carbon with controllable Ni nanorods for ethanol oxidation

International Nuclear Information System (INIS)

Shi, Wenjuan; Gao, Haiyan; Yu, Jianguo; Jia, Miaomiao; Dai, Tangming; Zhao, Yongnan; Xu, Jingjing; Li, Guodong

2016-01-01

N-doped activated carbons with controllable Ni nanorods (NiNC) catalysts were fabricated by a facile one-pot method for electrocatalytic oxidation of ethanol. The effects of carbon source and Ni precursor for the different microstructures of the forming Ni are discussed in this work. The sucrose and chloride ion are the key factors for forming nanorod-like nickel catalyst. The sizes of Ni nanorods can be controlled by the reactant ratios and influence the catalytic performance for ethanol oxidation. The doped N atoms are also used to improve the catalytic performance for ethanol oxidation. The NiNC–3 catalyst with the proper content and size of Ni exhibits an improved catalytic activity toward ethanol oxidation with a 5 times current density and 16 times rate constant in comparison with the NiNC–1 catalysts. A current density of 47.5 mA cm −2 is generated on NiNC–3 electrode. Furthermore, current density retention of 80.7% suggests an excellent cyclic stability after 1500 cycle on the NiNC–3 electrode. All of these elevated performances can be attributed to the relatively uniform nanorods size, as well as the excellent electrical conductivity and stability of the carbon support.

Carbon monoxide levels measured in major commuting corridors covering different landuse and roadway microenvironments in Hong Kong

Science.gov (United States)

Chan, L. Y.; Liu, Y. M.; Lee, S. C.; Chan, C. Y.

Vehicle exhaust is the major source of pollutant in modern cities. About half of Hong Kong residents are living in suburban or rural areas. They need to traverse through tunnels, highways, urban street canyons and other road conditions in different landuse areas when they traverse to work in urban centres or new towns. Also, there is increasing traffic, especially trucks across the border between Hong Kong and mainland China via several border highways. This study helps us in assessing the exposure level of suburban and cross border commuters. Carbon monoxide (CO) is used as a tracer for traffic emission. An experimental vehicle traversing major commuting corridors were used to measure CO levels in different landuse and roadway microenvironments including tunnels and highways. The air samples were taken simultaneously at the outside and inside of a travelling vehicle. Result indicates that the pattern of fluctuation of the out-vehicle and in-vehicle CO level vary with different landuse areas. The variation pattern of in-vehicle CO level is closely related to that of out-vehicle level. The effects of the out-vehicle CO concentration on the in-vehicle CO concentration under different roadway conditions in various landuse categories are examined. There is an indication that external air pollutants penetrated into the in-vehicle compartment through car body cracks, ventilation system. From our observation, the exhaust of a nearby petrol vehicle contributed significantly to the in-vehicle CO level. The use of low standard of diesel fuel from Shenzhen in mainland China leads to higher CO level near border area.

Carbon footprint of milk from sheep farming systems in northern Spain including soil carbon sequestration in grasslands

DEFF Research Database (Denmark)

Batalla, Inma M.; Knudsen, Marie Trydeman; Mogensen, Lisbeth

2015-01-01

The link between climate change and livestock production has made carbon footprint based on life cycle assessment a world-wide indicator to assess and communicate the amount of greenhouse gases emitted per unit of product. Nevertheless, the majority of studies have not included soil carbon seques...

Peptide methionine sulfoxide reductase A (MsrA): direct electrochemical oxidation on carbon electrodes.

Science.gov (United States)

Enache, T A; Oliveira-Brett, A M

2013-02-01

The direct electrochemical behaviour of peptide methionine sulfoxide reductase A (MsrA) adsorbed on glassy carbon and boron doped diamond electrodes surface, was studied over a wide pH range by cyclic and differential pulse voltammetry. MsrA oxidation mechanism occurs in three consecutive, pH dependent steps, corresponding to the oxidation of tyrosine, tryptophan and histidine amino acid residues. At the glassy carbon electrode, the first step corresponds to the oxidation of tyrosine and tryptophan residues and occurs for the same potential. The advantage of boron doped diamond electrode was to enable the separation of tyrosine and tryptophan oxidation peaks. On the second step occurs the histidine oxidation, and on the third, at higher potentials, the second tryptophan oxidation. MsrA adsorbs on the hydrophobic carbon electrode surface preferentially through the three hydrophobic domains, C1, C2 and C3, which contain the tyrosine, tryptophan and histidine residues, and tryptophan exists only in these regions, and undergo electrochemical oxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

One-Step Nickel Foam Assisted Synthesis of Holey G-Carbon Nitride Nanosheets for Efficient Visible-light Photocatalytic H2 Evolution.

Science.gov (United States)

Fang, Zhenyuan; Hong, Yuanzhi; Li, Di; Luo, Bifu; Mao, Baodong; Shi, Weidong

2018-06-01

Graphitic carbon nitride (g-C3N4) with layered structure represents one of the most promising metal-free photocatalysts. As yet, the direct one-step synthesis of ultrathin g-C3N4 nanosheets remains a challenge. Here, few-layered holey g-C3N4 nanosheets (CNS) were fabricated by simply introducing a piece of nickel foam over the precursors during the heating process. The as-prepared CNS with unique structural advantages exhibited superior photocatalytic water splitting activity (1871.09 µmol h-1 g-1) than bulk g-C3N4 (BCN) under visible light (λ>420 nm) (≈31 fold). Its outstanding photocatalytic performance originated from the high specific surface area (240.34 m2 g-1) and mesoporous structure, which endows CNS with more active sites, efficient exciton dissociation and prolonged charge carrier lifetime. Moreover, the obvious up-shift of the conduction band leads to a larger thermodynamic driving force for photocatalytic proton reduction. This methodology not only had the advantages for the direct and green synthesis of g-C3N4 nanosheets, but also paved a new avenue to modify molecular structure and textural of g-C3N4 for advanced applications.

Knee and ankle range of motion during stepping down in elderly compared to young men

NARCIS (Netherlands)

Lark, S.D.; Buckley, J.G.; Jones, D.A.; Sargeant, A.J.

2004-01-01

A major factor limiting mobility in elderly subjects is their difficulty with descending steps but the physiological and biomechanical basis of this problem is not well understood. To address this question we have compared the kinematics of stepping down in six elderly male subjects and six weight-

SNS Central Helium Liquefier spare Carbon Bed installation and commissioning

Energy Technology Data Exchange (ETDEWEB)

Degraff, Brian D. [ORNL; Howell, Matthew P. [ORNL; Kim, Sang-Ho [ORNL; Neustadt, Thomas S. [ORNL

2017-07-01

The Spallation Neutron Source (SNS) Central Helium Liquefier (CHL) at Oak Ridge National Laboratory (ORNL) has been without major operations downtime since operations were started back in 2006. This system utilizes a vessel filled with activated carbon as the final major component to remove oil vapor from the compressed helium circuit prior to insertion into the system's cryogenic cold box. The need for a spare carbon bed at SNS due to the variability of carbon media lifetime calculation to adsorption efficiency will be discussed. The fabrication, installation and commissioning of this spare carbon vessel will be presented. The novel plan for connecting the spare carbon vessel piping to the existing infrastructure will be presented.

One-step synthesis and characterization of CoS-Nanoparticles decorated multi-walled carbon nanotubes

CSIR Research Space (South Africa)

Kesavan Pillai, Sreejarani

2009-02-01

Full Text Available of applications. It is vital to develop efficient methods to attach quantum dots onto the sidewalls of CNTs whose structures have been preserved intact. In this study, a simple and facile one-step synthesis approach for the in situ mineralisation of Co...

The step complexity measure for emergency operating procedures - comparing with simulation data

International Nuclear Information System (INIS)

Park, Jinkyun; Jung, Wondea; Kim, Jaewhan; Ha, Jaejoo; Shin, Yunghwa

2001-01-01

In complex systems, such as nuclear power plants (NPPs) or airplane control systems, human errors play a major role in many accidents. Therefore, to prevent occurrences of accidents or to ensure system safety, extensive effort has been made to identify significant factors that cause human errors. According to related studies, written manuals or operating procedures are revealed as one of the most important factors, and complexity or understandability of a procedure is pointed out as one of the major reasons that make procedure-related human errors. Many qualitative checklists are suggested to evaluate emergency operating procedures (EOPs) of NPPs. However, since qualitative evaluations using checklists have some drawbacks, a quantitative measure that can quantify the complexity of EOPs is imperative to compensate for them. In order to quantify the complexity of EOPs, Park et al. suggested the step complexity (SC) measure to quantify the complexity of a step included in EOPs. In this paper, to ensure the appropriateness of the SC measure, SC scores are compared with averaged step performance time data obtained from emergency training records. The total number of available records is 36, and training scenarios are the loss of coolant accident and the excess steam dump event. The number of scenario is 18 each. From these emergency training records, step performance time data for 39 steps are retrieved, and they are compared with estimated SC scores of them. In addition, several questions that are needed to clarify the appropriateness of the SC measure are also discussed. As a result, it was observed that estimated SC scores and step performance time data have a statistically meaningful correlation. Thus, it can be concluded that the SC measure can quantify the complexity of steps included in EOPs

The way to collisions, step by step

CERN Multimedia

2009-01-01

While the LHC sectors cool down and reach the cryogenic operating temperature, spirits are warming up as we all eagerly await the first collisions. No reason to hurry, though. Making particles collide involves the complex manoeuvring of thousands of delicate components. The experts will make it happen using a step-by-step approach.

Liberating energy from carbon introduction to decarbonization

CERN Document Server

Muradov, Nazim

2014-01-01

Liberating Energy from Carbon analyzes energy options in a carbon-constrained world. Major strategies and pathways to decarbonizing the carbon-intensive economy are laid out with a special emphasis on the prospects of achieving low-risk atmospheric CO2 levels. The opportunities and challenges in developing and bringing to market novel low and zero-carbon technologies are highlighted from technical, economic and environmental viewpoints. This book takes a unique approach by treating carbon in a holistic manner?tracking its complete transformation chain from fossil fuel sources to the unique pro

Carbon-14 dating of groundwater under Christchurch, 1976 samples

International Nuclear Information System (INIS)

Stewart, M.K.; Brenninkmeijer, C.A.M.; Brown, L.J.

1986-06-01

Four samples of groundwater from deep aquifers under Christchurch have been analysed for carbon-14, tritium, oxygen-18 and chemical contents. Interpretation of the carbon-14 results requires two steps, (1) correction of the measured 14 C values for input of dead ( 14 C-free) carbon underground (indicating that the measured values of 80 PMC* should be increased to about 120 PMC), and (2) determination of water residence times for given flow models of the groundwater system. Interpretation of tritium results involves step 2 only. Three models are considered, of which the third is considered most appropriate to Christchurch. In this model, the 14 C and T results indicate that a small proportion of young water (post-1954) mixes with a larger proportion of older water (probably at least several hundred years). The oxygen-18 content indicates that recharge is mainly from the Waimakariri River and possibly from rainfall and streams near the foothills of the Canterbury Plains. Other aspect of the groundwater flow under Christchurch are discussed

Ultrahigh surface area carbon from carbonated beverages: Combining self-templating process and in situ activation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Pengfei; Zhang, Zhiyong; Chen, Jihua; Dai, Sheng

2015-11-01

Ultrahigh surface area carbons (USACs, e.g., >2000 m2/g) are attracting tremendous attention due to their outstanding performance in energy-related applications. The state-of-art approaches to USACs involve templating or activation methods and all these techniques show certain drawbacks. In this work, a series of USACs with specific surface areas up to 3633 m2/g were prepared in two steps: hydrothermal carbonization (200 °C) of carbonated beverages (CBs) and further thermal treatment in nitrogen (600–1000 °C). The rich inner porosity is formed by a self-templated process during which acids and polyelectrolyte sodium salts in the beverage formulas make some contribution. This strategy covers various CBs such as Coca Cola®, Pepsi Cola®, Dr. Pepper®, and Fanta® and it enables an acceptable product yield (based on sugars), for example: 21 wt% for carbon (2940 m2/g) from Coca Cola®. Being potential electrode materials for supercapacitors, those carbon materials possessed a good specific capacitance (57.2–185.7 F g-1) even at a scan rate of 1000 mV s-1. Thus, a simple and efficient strategy to USACs has been presented.

Ocean Fertilization for Sequestration of Carbon Dioxide from the Atmosphere

Science.gov (United States)

Boyd, Philip W.

The ocean is a major sink for both preindustrial and anthropogenic carbon dioxide. Both physically and biogeochemically driven pumps, termed the solubility and biological pump, respectively Fig.5.1) are responsible for the majority of carbon sequestration in the ocean's interior [1]. The solubility pump relies on ocean circulation - specifically the impact of cooling of the upper ocean at high latitudes both enhances the solubility of carbon dioxide and the density of the waters which sink to great depth (the so-called deepwater formation) and thereby sequester carbon in the form of dissolved inorganic carbon (Fig.5.1). The biological pump is driven by the availability of preformed plant macronutrients such as nitrate or phosphate which are taken up by phytoplankton during photosynthetic carbon fixation. A small but significant proportion of this fixed carbon sinks into the ocean's interior in the form of settling particles, and in order to maintain equilibrium carbon dioxide from the atmosphere is transferred across the air-sea interface into the ocean (the so-called carbon drawdown) thereby decreasing atmospheric carbon dioxide (Fig.5.1).Fig.5.1

Endoscopic or surgical step-up approach for infected necrotising pancreatitis: a multicentre randomised trial.

Science.gov (United States)

van Brunschot, Sandra; van Grinsven, Janneke; van Santvoort, Hjalmar C; Bakker, Olaf J; Besselink, Marc G; Boermeester, Marja A; Bollen, Thomas L; Bosscha, Koop; Bouwense, Stefan A; Bruno, Marco J; Cappendijk, Vincent C; Consten, Esther C; Dejong, Cornelis H; van Eijck, Casper H; Erkelens, Willemien G; van Goor, Harry; van Grevenstein, Wilhelmina M U; Haveman, Jan-Willem; Hofker, Sijbrand H; Jansen, Jeroen M; Laméris, Johan S; van Lienden, Krijn P; Meijssen, Maarten A; Mulder, Chris J; Nieuwenhuijs, Vincent B; Poley, Jan-Werner; Quispel, Rutger; de Ridder, Rogier J; Römkens, Tessa E; Scheepers, Joris J; Schepers, Nicolien J; Schwartz, Matthijs P; Seerden, Tom; Spanier, B W Marcel; Straathof, Jan Willem A; Strijker, Marin; Timmer, Robin; Venneman, Niels G; Vleggaar, Frank P; Voermans, Rogier P; Witteman, Ben J; Gooszen, Hein G; Dijkgraaf, Marcel G; Fockens, Paul

2018-01-06

Infected necrotising pancreatitis is a potentially lethal disease and an indication for invasive intervention. The surgical step-up approach is the standard treatment. A promising alternative is the endoscopic step-up approach. We compared both approaches to see whether the endoscopic step-up approach was superior to the surgical step-up approach in terms of clinical and economic outcomes. In this multicentre, randomised, superiority trial, we recruited adult patients with infected necrotising pancreatitis and an indication for invasive intervention from 19 hospitals in the Netherlands. Patients were randomly assigned to either the endoscopic or the surgical step-up approach. The endoscopic approach consisted of endoscopic ultrasound-guided transluminal drainage followed, if necessary, by endoscopic necrosectomy. The surgical approach consisted of percutaneous catheter drainage followed, if necessary, by video-assisted retroperitoneal debridement. The primary endpoint was a composite of major complications or death during 6-month follow-up. Analyses were by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN09186711. Between Sept 20, 2011, and Jan 29, 2015, we screened 418 patients with pancreatic or extrapancreatic necrosis, of which 98 patients were enrolled and randomly assigned to the endoscopic step-up approach (n=51) or the surgical step-up approach (n=47). The primary endpoint occurred in 22 (43%) of 51 patients in the endoscopy group and in 21 (45%) of 47 patients in the surgery group (risk ratio [RR] 0·97, 95% CI 0·62-1·51; p=0·88). Mortality did not differ between groups (nine [18%] patients in the endoscopy group vs six [13%] patients in the surgery group; RR 1·38, 95% CI 0·53-3·59, p=0·50), nor did any of the major complications included in the primary endpoint. In patients with infected necrotising pancreatitis, the endoscopic step-up approach was not superior to the surgical step-up approach in reducing major

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

International Nuclear Information System (INIS)

Froment, A.K.

1990-01-01

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

Comparison of microbial community shifts in two parallel multi-step drinking water treatment processes.

Science.gov (United States)

Xu, Jiajiong; Tang, Wei; Ma, Jun; Wang, Hong

2017-07-01

Drinking water treatment processes remove undesirable chemicals and microorganisms from source water, which is vital to public health protection. The purpose of this study was to investigate the effects of treatment processes and configuration on the microbiome by comparing microbial community shifts in two series of different treatment processes operated in parallel within a full-scale drinking water treatment plant (DWTP) in Southeast China. Illumina sequencing of 16S rRNA genes of water samples demonstrated little effect of coagulation/sedimentation and pre-oxidation steps on bacterial communities, in contrast to dramatic and concurrent microbial community shifts during ozonation, granular activated carbon treatment, sand filtration, and disinfection for both series. A large number of unique operational taxonomic units (OTUs) at these four treatment steps further illustrated their strong shaping power towards the drinking water microbial communities. Interestingly, multidimensional scaling analysis revealed tight clustering of biofilm samples collected from different treatment steps, with Nitrospira, the nitrite-oxidizing bacteria, noted at higher relative abundances in biofilm compared to water samples. Overall, this study provides a snapshot of step-to-step microbial evolvement in multi-step drinking water treatment systems, and the results provide insight to control and manipulation of the drinking water microbiome via optimization of DWTP design and operation.

Major oil exporters may profit rather than lose, in a carbon-constrained world

International Nuclear Information System (INIS)

Persson, Tobias A.; Azar, C.; Johansson, D.; Lindgren, K.

2007-01-01

The Organization of Petroleum Exporting Countries (OPEC) claims compensation for losses in expected oil export revenues due to CO 2 mitigation measures in developing countries. These losses are expected for two primary reasons: a reduction in the consumption of oil in importing countries and a reduction in the producer price of oil (taxation in an importing country implies a transfer of rents from producers to consumers). So far, most studies have focused on these two mechanisms and corroborated that revenue losses for OPEC are to be expected. However, there are also mechanisms that may be expected to raise the price of oil products. In a cost-effective regime for dealing with climate change, i.e., a regime in which all or most countries participate and in which the same carbon price is applied on all carbon-emitting activities, the cost of using unconventional oil, or synthetic diesel from coal, will increase even more than the cost of using conventional oil. Given that reserves of conventional oil are expected to dwindle over time, heavy oils and coal to liquids might set the long-run price for liquid fuels, which means that the price of oil would increase beyond the carbon fee; i.e., the rent on conventional oil would increase. We use an energy-economic optimization model to analyze these three mechanisms. We find that the net present value of OPEC revenue from conventional oil increases slightly (at most by 4 percent) with a global CO 2 restriction regime. We also consider conditions under which this result does not hold

Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites

Science.gov (United States)

Vaughn, Wallace L.; Scotti, Stephan J.; Ashe, Melissa P.; Connolly, Liz

2007-01-01

A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon-carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to re-entry into the atmosphere of the Earth. According to one of the slides, creep forming would be an intermediate step in a process that would yield a fully densified, finished C-CMC part having a desired size and shape (the other steps would include preliminary machining, finish machining, densification by chemical vapor infiltration, and final coating). The investigation included experiments in which C-CMC disks were creep-formed by heating them to unspecified high temperatures for time intervals of the order of 1 hour while they were clamped into single- and double-curvature graphite molds. The creep-formed disks were coated with an oxidation- protection material, then subjected to arc-jet tests, in which the disks exhibited no deterioration after exposure to high-temperature test conditions lasting 490 seconds.

Estimating heterotrophic respiration at large scales: Challenges, approaches, and next steps

Science.gov (United States)

Bond-Lamberty, Ben; Epron, Daniel; Harden, Jennifer W.; Harmon, Mark E.; Hoffman, Forrest; Kumar, Jitendra; McGuire, Anthony David; Vargas, Rodrigo

2016-01-01

Heterotrophic respiration (HR), the aerobic and anaerobic processes mineralizing organic matter, is a key carbon flux but one impossible to measure at scales significantly larger than small experimental plots. This impedes our ability to understand carbon and nutrient cycles, benchmark models, or reliably upscale point measurements. Given that a new generation of highly mechanistic, genomic-specific global models is not imminent, we suggest that a useful step to improve this situation would be the development of “Decomposition Functional Types” (DFTs). Analogous to plant functional types (PFTs), DFTs would abstract and capture important differences in HR metabolism and flux dynamics, allowing modelers and experimentalists to efficiently group and vary these characteristics across space and time. We argue that DFTs should be initially informed by top-down expert opinion, but ultimately developed using bottom-up, data-driven analyses, and provide specific examples of potential dependent and independent variables that could be used. We present an example clustering analysis to show how annual HR can be broken into distinct groups associated with global variability in biotic and abiotic factors, and demonstrate that these groups are distinct from (but complementary to) already-existing PFTs. A similar analysis incorporating observational data could form the basis for future DFTs. Finally, we suggest next steps and critical priorities: collection and synthesis of existing data; more in-depth analyses combining open data with rigorous testing of analytical results; using point measurements and realistic forcing variables to constrain process-based models; and planning by the global modeling community for decoupling decomposition from fixed site data. These are all critical steps to build a foundation for DFTs in global models, thus providing the ecological and climate change communities with robust, scalable estimates of HR.

Nanophase Carbonates on Mars: Implications for Carbonate Formation and Habitability

Science.gov (United States)

Archer, P. Douglas, Jr.; Lauer, H. Vern; Ming, Douglas W.; Niles, Paul B.; Morris, Richard V.; Rampe, Elizabeth B.; Sutter, Brad

2014-01-01

Despite having an atmosphere composed primarily of CO2 and evidence for abundant water in the past, carbonate minerals have only been discovered in small amounts in martian dust [1], in outcrops of very limited extent [2, 3], in soils in the Northern Plains (the landing site of the 2007 Phoenix Mars Scout Mission) [4] and may have recently been detected in aeolian material and drilled and powdered sedimentary rock in Gale Crater (the Mars Science Laboratory [MSL] landing site) [5]. Thermal analysis of martian soils by instruments on Phoenix and MSL has demonstrated a release of CO2 at temperatures as low as 250-300 degC, much lower than the traditional decomposition temperatures of calcium or magnesium carbonates. Thermal decomposition temperature can depend on a number of factors such as instrument pressure and ramp rate, and sample particle size [6]. However, if the CO2 released at low temperatures is from carbonates, small particle size is the only effect that could have such a large impact on decomposition temperature, implying the presence of extremely fine-grained (i.e., "nanophase" or clay-sized) carbonates. We hypothesize that this lower temperature release is the signature of small particle-sized (clay-sized) carbonates formed by the weathering of primary minerals in dust or soils through interactions with atmospheric water and carbon dioxide and that this process may persist under current martian conditions. Preliminary work has shown that clay-sized carbonate grains can decompose at much lower temperatures than previously thought. The first work took carbonate, decomposed it to CaO, then flowed CO2 over these samples held at temperatures >100 degC to reform carbonates. Thermal analysis confirmed that carbonates were indeed formed and transmission electron microsopy was used to determine crystal sized were on the order of 10 nm. The next step used minerals such as diopside and wollastonite that were sealed in a glass tube with a CO2 and H2O source. After

Study of 16O(12C,α20Ne)α for the investigation of carbon-carbon fusion reaction via the Trojan Horse Method

International Nuclear Information System (INIS)

Rapisarda, G.G.; Spitaleri, C; Kiss, G.G.; La Cognata, M.; Pizzone, R.G.; Romano, S.; Tumino, A.; Bordeanu, C.; Nita, C.; Pantelica, D.; Petrascu, H.; Velisa, G.; Hons, Z.; Mrazek, J.; Szücs, T.; Trache, L.

2016-01-01

Carbon-carbon fusion reaction represents a nuclear process of great interest in astrophysics, since the carbon burning is connected with the third phase of massive stars (M > 8 M ☉ ) evolution. In spite of several experimental works, carbon-carbon cross section has been measured at energy still above the Gamow window moreover data at low energy present big uncertainty. In this paper we report the results about the study of the 16 O( 12 C,α 20 Ne)α reaction as a possible three-body process to investigate 12 C( 12 C,α) 20 Ne at astrophysical energy via Trojan Horse Method (THM). This study represents the first step of a program of experiments aimed to measure the 12 C+ 12 C cross section at astrophysical energy using the THM. (paper)

Poly(ethylene-co-butylene) functionalized multi walled carbon nanotubes applied in polypropylene nanocomposites

DEFF Research Database (Denmark)

Daugaard, Anders Egede; Jankova Atanasova, Katja; Marín, Jose Manuel Roman

2012-01-01

A novel functionalized multi walled carbon nanotube (MWCNT) was prepared through grafting with α-azido-poly(ethylene-co-butylene) (PEB-N3). The PEB-N3 was prepared through a two step procedure and grafted onto an industrial grade multi walled carbon nanotube (MWCNT) through a highly efficient...

Calcifying Cyanobacteria - The potential of biomineralization for Carbon Capture and Storage

Energy Technology Data Exchange (ETDEWEB)

Jansson, Christer G; Northen, Trent

2010-03-26

Employment of cyanobacteria in biomineralization of carbon dioxide by calcium carbonate precipitation offers novel and self-sustaining strategies for point-source carbon capture and sequestration. Although details of this process remain to be elucidated, a carbon-concentrating mechanism, and chemical reactions in exopolysaccharide or proteinaceous surface layers are assumed to be of crucial importance. Cyanobacteria can utilize solar energy through photosynthesis to convert carbon dioxide to recalcitrant calcium carbonate. Calcium can be derived from sources such as gypsum or industrial brine. A better understanding of the biochemical and genetic mechanisms that carry out and regulate cynaobacterial biomineralization should put us in a position where we can further optimize these steps by exploiting the powerful techniques of genetic engineering, directed evolution, and biomimetics.

One-step synthesis of shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond as efficient electrocatalyst for the oxygen reduction reaction in alkaline media

International Nuclear Information System (INIS)

Liu, Xiaoxu; Wang, Yanhui; Dong, Liang; Chen, Xi; Xin, Guoxiang; Zhang, Yan; Zang, Jianbing

2016-01-01

Shell/core structural boron and nitrogen co-doped graphitic carbon/nanodiamond (BN-C/ND) non-noble metal catalyst has been synthesized by a simple one-step heat-treatment of the mixture with nanodiamond, melamine, boric acid and FeCl 3 . In the process of the surface graphitization of nanodiamond with catalysis by FeCl 3 , B and N atoms from the decomposition of boric acid and melamine were directly introduced into the graphite lattice to form B, N co-doped graphitic carbon shell, while the core still retained the diamond structure. Electrochemical measurements of the BN-C/ND catalyst show much higher electrocatalytic activities towards oxygen reduction reaction (ORR) in alkaline medium than its analogues doped with B or N alone (B-C/ND or N-C/ND). The high catalytic activity of BN-C/ND is attributed to the synergetic effect caused by co-doping of C/ND with B and N. Meanwhile, the BN-C/ND exhibits an excellent electrochemical stability due to the special shell/core structure. There is almost no alteration occurred in the cyclic voltammetry measurements for BN-C/ND before and after 5000 cycles. All experimental results prove that the BN-C/ND may be exploited as a potentially efficient and inexpensive non-noble metal cathode catalyst for ORR to substitute Pt-based catalysts in fuel cells.

Recyclable crosslinked polymer networks with full property recovery made via one-step controlled radical polymerization

Science.gov (United States)

Jin, Kailong; Li, Lingqiao; Torkelson, John

Rubber tires illustrate well the issues ranging from economic loss to environmental problems and sustainability issues that arise with spent, covalently crosslinked polymers. A nitroxide-mediated polymerization (NMP) strategy has been developed that allows for one-step synthesis of recyclable crosslinked polymers from monomers or polymers that contain carbon-carbon double bonds amenable to radical polymerization. Resulting materials possess dynamic alkoxyamine crosslinks that undergo reversible decrosslinking as a function of temperature. Using polybutadiene as starting material, and styrene, an appropriate nitroxide molecule and bifunctional initiator for initial crosslinking, a model for tire rubber can be produced by reaction at temperatures comparable to those employed in tire molding. Upon cooling, the crosslinks are made permanent due to the extraordinarily strong temperature dependence of the reverisible nitroxide capping and uncapping reaction. Based on thermomechanical property characterization, when the original crosslinked model rubber is chopped into bits and remolded in the melt state, a well-consolidated material is obtained which exhibits full recovery of properties reflecting crosslink density after multiple recycling steps.

Characterisation of a major enzyme of bovine nitrogen metabolism

CSIR Research Space (South Africa)

Mathomu, LM

2010-09-01

Full Text Available of cellular protein metabolism (Curthoys & Watford, 1995; Meister, 1974). Glutamine functions as a major inter-organ transport form of nitrogen, carbon and serves as a source of energy between tissues such as brain, liver, kidney and even muscles...

Developing Major Steps for a Feasibility Study for Upgrading I and C Systems in a Large Scale for an Operating Nuclear Power Plant

International Nuclear Information System (INIS)

Suh, Yong Suk; Keum, Jong Yong; Kim, Dong Hoon; Kang, Hyeon Tae; Sung, Chan Ho; Lee, Jae Ki; Cho, Chang Hwan

2009-01-01

According to the IAEA report as of Jan. 2008, 436 nuclear power reactors are in operation over the world and 368 nuclear power reactors exceed their operating ages by 20 years. The average I and C equipment's life span is 20 years comparing with that the average reactor's life time is 40 to 60 years. This means that a reactor must be faced with I and C equipment obsolescence problems once or twice during its operating years. The I and C equipment is replaced with new equipment only when the obsolescence problem occurs in a nuclear power plant. This is called an equipment basis upgrade in this paper. This replacement is such a general practice that occurs only when needed. We can assume that most of I and C equipment of a plant will meet with the obsolescence problem almost same time since it started operating. Although there must be a little time difference in the occurrence of the problems among I and C equipment, the replacement will be required in consecutive years. With this assumption, it is recommendable to upgrade the equipment, which is to meet with the problem at the same time, with new equipment at the same time. This is called a system basis upgrade in this paper. The system-basis replacement can be achieved in a large scale by coupling systems whose functions are related each other and replacing them together with a new upto- date platform. This paper focuses on the large scale upgrade of I and C systems for existing and operating NPPs. While performing a feasibility study for the large scale upgrade for Korea standard nuclear power plants (KSNPs), six major steps are developed for the study. This paper is to present what to perform in each step

A parallel nearly implicit time-stepping scheme

OpenAIRE

Botchev, Mike A.; van der Vorst, Henk A.

2001-01-01

Across-the-space parallelism still remains the most mature, convenient and natural way to parallelize large scale problems. One of the major problems here is that implicit time stepping is often difficult to parallelize due to the structure of the system. Approximate implicit schemes have been suggested to circumvent the problem. These schemes have attractive stability properties and they are also very well parallelizable. The purpose of this article is to give an overall assessment of the pa...

Deep Carbon Observatory investigates Carbon from Crust to Core: An Academic Record of the History of Deep Carbon Science

Science.gov (United States)

Mitton, S. A.

2017-12-01

Carbon plays an unparalleled role in our lives: as the element of life, as the basis of most of society's energy, as the backbone of most new materials, and as the central focus in efforts to understand Earth's variable and uncertain climate. Yet in spite of carbon's importance, scientists remain largely ignorant of the physical, chemical, and biological behavior of many of Earth's carbon-bearing systems. The Deep Carbon Observatory (DCO) is a global research program to transform our understanding of carbon in Earth. At its heart, DCO is a community of scientists, from biologists to physicists, geoscientists to chemists, and many others whose work crosses these disciplinary lines, forging a new, integrative field of deep carbon science. As a historian of science, I specialise in the history of planetary science and astronomy since 1900. This is directed toward understanding of the history of the steps on the road to discovering the internal dynamics of our planet. Within a framework that describes the historical background to the new field of Earth System Science, I present the first history of deep carbon science. This project will identifies the key discoveries of deep carbon science. It will assess the impact of new knowledge on geochemistry, geodynamics, and geobiology. The project will lead to publication, in book form in 2019, of an illuminating narrative that will highlight the engaging human stories of many remarkable scientists and natural philosophers from whom we have learned about the complexity of Earth's internal world. On this journey of discovery we will encounter not just the pioneering researchers of deep carbon science, but also their institutions, their instrumental inventiveness, and their passion for exploration. The book is organised thematically around the four communities of the Deep Carbon Observatory: Deep Life, Extreme Physics and Chemistry, Reservoirs and Fluxes, and Deep Energy. The presentation has a gallery and list of Deep Carbon

Pyrolytic carbon membranes containing silica: morphological approach on gas transport behavior

Science.gov (United States)

Park, Ho Bum; Lee, Sun Yong; Lee, Young Moo

2005-04-01

Pyrolytic carbon membrane containing silica (C-SiO 2) is a new-class material for gas separation, and in the present work we will deal with it in view of the morphological changes arising from the difference in the molecular structure of the polymeric precursors. The silica embedded carbon membranes were fabricated by a predetermined pyrolysis step using imide-siloxane copolymers (PISs) that was synthesized from benzophenone tetracarboxylic dianhydrides (BTDA), 4,4'-oxydianiline (ODA), and amine-terminated polydimethylsiloxane (PDMS). To induce different morphologies at the same chemical composition, the copolymers were prepared using one-step (preferentially a random segmented copolymer) sand two-step polymerization (a block segmented copolymer) methods. The polymeric precursors and their pyrolytic C-SiO 2 membranes were analyzed using thermal analysis, atomic force microscopy, and transmission electron microscopy, etc. It was found that the C-SiO 2 membrane derived from the random PIS copolymer showed a micro-structure containing small well-dispersed silica domains, whereas the C-SiO 2 membrane from the block PIS copolymer exhibited a micro-structure containing large silica domains in the continuous carbon matrix. Eventually, the gas transport through these C-SiO 2 membranes was significantly affected by the morphological changes of the polymeric precursors.

Cloning and expression of gamma carbonic anhydrase from Serratia sp. ISTD04 for sequestration of carbon dioxide and formation of calcite.

Science.gov (United States)

Srivastava, Shaili; Bharti, Randhir Kumar; Verma, Praveen Kumar; Thakur, Indu Shekhar

2015-01-01

Bacterial strains isolated from marble mines rock and enriched in the chemostat culture with different concentrations of sodium bicarbonate. The enriched consortium had six bacterial isolates. One of bacterium isolate showed carbonic anhydrase (CA) activity by catalyzing the reversible hydration reaction of carbon dioxide to bicarbonate. The bacterium was identified as Serratia sp. by 16S rRNA sequence analysis. The carbonic anhydrase gene from Serratia sp. was found to be homologous with gamma carbonic anhydrase. The carbonic anhydrase gene was cloned in PET21b(+) and expressed it in recombinant Escherichia coli BL21 (DE3) with His-tag at the C-terminus. The recombinant protein was purified efficiently by using one-step nickel affinity chromatography. Expected size of carbonic anhydrase was approximately 29 kDa in SDS-PAGE gel. Recombinant carbonic anhydrase enzyme was used for biomineralization-based conversion of atmospheric CO2 into valuable calcite minerals. The calcification was confirmed by using XRD, FTIR, EDX and SEM analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon mitigation technologies for emerging economies

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-05-15

A review of the various options being pursued to reduce carbon intensities in five developing countries, namely Brazil, China, India, Indonesia and South Africa. These are major emerging economies, all of which are vulnerable to adverse effects from climate change, with their governments having to balance economic, environmental and social priorities. All have large carbon footprints; however, in each case, they have made commitments to reduce carbon intensities over the period to 2030 and, in some cases, beyond.

Application of the DIY carbon footprint calculator to a wastewater ...

African Journals Online (AJOL)

In order to manage the energy budget and develop climate-friendly technological ... step involves the development of strategies to reduce the carbon footprint. ..... Intelligent management systems: aeration of the activated sludge process.

Carbonated water (CW) process waste reuse for ammonium-uranyl-carbonate (AUC) production and its gains on the environmental, economic and social aspects

International Nuclear Information System (INIS)

Carnaval, Joao Paulo R.; Santos, Rafael D. dos; Barbosa, Rodrigo A.; Lauer, Sergio

2013-01-01

In the INB nuclear fuel cycle, the pellets production is based on UO 2 powder made by AUC (Ammonium-Uranyl-Carbonate) route. AUC formation occurs by fluidising of UF 6 , NH 3 and CO 2 in a vase containing usually pure water, and this exothermal reaction has AUC as direct product. The mass formed is filtered, washed with CW, washed again with methano solution, dried with air and conducted to the fluidized bed furnace, to be converted to UO 2 powder. At this point, the dried AUC decompounds to UO 3 , NH 3 and C0 2 , these 2 gases are absorbed at the gases washer, formin go the carbonated water (CW), whit is basically a (NH 4 ) 2 CO 3 solution. The UO 2+x is reduced and stabilized to UO 2 powder, which is conducted to pellets production. During the process, a considerable amount of this aqueous waste is generated and goes for effluent treatment. After that, the solution is sent for spray-dryer for power formation, and stock. This treatment demands equipment, energy and time, representing considerable costs of the company beyond the human risks involved on the drying step. The purpose of this work is to present a study of the carbonated water use as substitute of pure water in the AUC formation step. At this point, tests were made varying the CW loads for the AUC precipitation, and the control was made by the UO 2 powder properties. The carbonated water used for AUC precipitation has been tested at several levels and the results has demonstrated full viability to become a definitive process step (INB, Resende site). It has been demonstrated the great resources economy caused by the waste reuse and the guarantee product quality. This represents such an environmental gain and also economic and social aspects got improved. (author)

Effect of two-step and one-step surface conditioning of glass ceramic on adhesion strength of orthodontic bracket and effect of thermo-cycling on adhesion strength.

Science.gov (United States)

Asiry, Moshabab A; AlShahrani, Ibrahim; Alaqeel, Samer M; Durgesh, Bangalore H; Ramakrishnaiah, Ravikumar

2018-08-01

The adhesion strength of orthodontic brackets bonded to dental glass ceramics was evaluated after ceramic surface was treated with two-step and one-step surface conditioning systems, and subjecting to thermo-cycling. A total of forty specimens were fabricated from silica based glass ceramic (lithium disilicate) by duplicating the buccal surface of maxillary first premolar. The specimens were randomly assigned to two experimental groups (n = 20), group one specimens were treated with two-step surface conditioning system (IPS ceramic etching gel™ and Monobond plus™) and group two specimens were treated with one-step surface conditioning system (Monobond etch and prime™). The surface roughness of the specimens after treatment with two-step and one-step surface conditioning system was measured using non-contact surface profilometer. Ten randomly selected specimens from each group were subjected to thermo-cycling and the remaining ten served as baseline. The shear bond strength of the specimens was measured using universal material testing machine. The adhesive remnant index score was calculated, and the results of surface roughness and bond strength were tabulated and subjected to analysis of variance and post hoc tukey's test at a significance level of p step conditioning system had higher surface roughness and bond strength than one-step conditioning system. The majority of the specimens treated with both two-step and one-step conditioned specimens showed adhesive failure after subjecting thermo-cycling. Traditional two-step conditioning provides better bond strength. The clinical importance of the study is that, the silane promoted adhesion significantly reduces on exposure to thermo-cycling. Copyright © 2018 Elsevier Ltd. All rights reserved.

[The investigation of control mechanisms of stepping rhythm in human in the air-stepping conditions during passive and voluntary leg movements].

Science.gov (United States)

Solopova, I A; Selionon, V A; Grishin, A A

2010-01-01

In unloading condition the degree of activation of the central stepping program was investigated during passive leg movements in healthy subjects, as well as the excitability of spinal motoneurons during passive and voluntary stepping movement. Passive stepping movements with characteristics maximally approximated to those during voluntary stepping were accomplished by experimenter. The comparison of the muscle activity bursts during voluntary and imposed movements was made. In addition to that the influence of artificially created loading onto the foot to the leg movement characteristics was analyzed. Spinal motoneuron excitability was estimated by means of evaluation of amplitude modulation of the soleus H-reflex. The changes of H-reflexes under the fixation of knee or hip joints were also studied. In majority of subjects the passive movements were accompanied by bursts of EMG activity of hip muscles (and sometimes of knee muscles), which timing during step cycle was coincided with burst timing of voluntary step cycle. In many cases the bursts of EMG activity during passive movements exceeded activity in homonymous muscles during voluntary stepping. The foot loading imitation exerted essential influence on distal parts of moving extremity during voluntary as well passive movements, that was expressed in the appearance of movements in the ankle joint and accompanied by emergence and increasing of phasic EMG activity of shank muscles. The excitability of motoneurons during passive movements was greater then during voluntary ones. The changes and modulation of H-reflex throughout the step cycle without restriction of joint mobility and during exclusion of hip joint mobility were similar. The knee joint fixation exerted the greater influence. It is supposed that imposed movements activate the same mechanisms of rhythm generation as a supraspinal commands during voluntary movements. In the conditions of passive movements the presynaptic inhibition depend on afferent

Ten thousand steps: a pedometer study of junior dentists in a major British teaching hospital and a district general hospital.

Science.gov (United States)

Keat, R M; Thomas, M; McKechnie, A

2017-05-01

Sedentary behaviour is widely associated with deleterious health outcomes that in modern medicine have similar connotations to smoking tobacco and alcohol misuse. The integration of e-portfolio, e-logbook, British National Formulary (BNF) and encrypted emails has made smartphones a necessity for trainees. Smartphones also have the ability to record the amount of exercise taken, which allows activity at work to be monitored. The aim of this study to compare the activity of the same group of dental core trainees when they worked within a large multisite teaching hospital and a smaller district general hospital, to find out if supplementary activity was needed outside work. Data were collected from smartphones. To ensure continuity, data were collected only from those who had calibrated iPhones (n=10). At the teaching hospital six of the trainees walked over 10 000 steps a day while working (mean (SD) 10 004 (639)). At the district hospital none of the trainees walked 10 000 steps. The mean (SD) number of steps completed by all trainees was 6265 (119). Walking at work provides the full quota of recommended daily exercise most of the time for those working in the teaching hospital, but additional exercise is occasionally required. While working at the district hospital they walk less, meaning that they should try to increase their activity outside work. Trainees working in the teaching hospital walk significantly more steps than in the district hospital. Copyright © 2016 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Solvothermal one-step synthesis of Ni-Al layered double hydroxide/carbon nanotube/reduced graphene oxide sheet ternary nanocomposite with ultrahigh capacitance for supercapacitors.

Science.gov (United States)

Yang, Wanlu; Gao, Zan; Wang, Jun; Ma, Jing; Zhang, Milin; Liu, Lianhe

2013-06-26

A Ni-Al layered double hydroxide (LDH), mutil-wall carbon nanotube (CNT), and reduced graphene oxide sheet (GNS) ternary nanocomposite electrode material has been developed by a facile one-step ethanol solvothermal method. The obtained LDH/CNT/GNS composite displayed a three-dimensional (3D) architecture with flowerlike Ni-Al LDH/CNT nanocrystallites gradually self-assembled on GNS nanosheets. GNS was used as building blocks to construct 3D nanostructure, and the LDH/CNT nanoflowers in turn separated the two-dimensional (2D) GNS sheets, which preserved the high surface area of GNSs. Furthermore, the generated porous networks with a narrow pore size distribution in the LDH/CNT/GNS composite were also demonstrated by the N2 adsorption/desorption experiment. Such morphology would be favorable to improve the mass transfer and electrochemical action of the electrode. As supercapacitor electrode material, the LDH/CNT/GNS hybrid exhibited excellent electrochemical performance, including ultrahigh specific capacitance (1562 F/g at 5 mA/cm(2)), excellent rate capability, and long-term cycling performance, which could be a promising energy storage/conversion material for supercapacitor application.

Specialists' meeting on carbon in sodium. Summary report

International Nuclear Information System (INIS)

1980-05-01

The purpose of the meeting was to provide a forum for the exchange of views on: the chemistry and thermodynamics of carbon in sodium; the analysis and monitoring of carbon in sodium; the behaviour of carbon in sodium circuits; and the implications of the above in LMFBRs. The technical parts of the meeting were divided into five major sessions

Specialists' meeting on carbon in sodium. Summary report

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-05-01

The purpose of the meeting was to provide a forum for the exchange of views on: the chemistry and thermodynamics of carbon in sodium; the analysis and monitoring of carbon in sodium; the behaviour of carbon in sodium circuits; and the implications of the above in LMFBRs. The technical parts of the meeting were divided into five major sessions.

Production of palm kernel shell-based activated carbon by direct physical activation for carbon dioxide adsorption.

Science.gov (United States)

Rashidi, Nor Adilla; Yusup, Suzana

2018-05-09

The feasibility of biomass-based activated carbons has received a huge attention due to their excellent characteristics such as inexpensiveness, good adsorption behaviour and potential to reduce a strong dependency towards non-renewable precursors. Therefore, in this research work, eco-friendly activated carbon from palm kernel shell that has been produced from one-stage physical activation by using the Box-Behnken design of Response Surface Methodology is highlighted. The effect of three input parameters-temperature, dwell time and gas flow rate-towards product yield and carbon dioxide (CO 2 ) uptake at room temperature and atmospheric pressure are studied. Model accuracy has been evaluated through the ANOVA analysis and lack-of-fit test. Accordingly, the optimum condition in synthesising the activated carbon with adequate CO 2 adsorption capacity of 2.13 mmol/g and product yield of 25.15 wt% is found at a temperature of 850 °C, holding time of 60 min and CO 2 flow rate of 450 cm 3 /min. The synthesised activated carbon has been characterised by diverse analytical instruments including thermogravimetric analyser, scanning electron microscope, as well as N 2 adsorption-desorption isotherm. The characterisation analysis indicates that the synthesised activated carbon has higher textural characteristics and porosity, together with better thermal stability and carbon content as compared to pristine palm kernel shell. Activated carbon production via one-step activation approach is economical since its carbon yield is within the industrial target, whereas CO 2 uptake is comparable to the synthesised activated carbon from conventional dual-stage activation, commercial activated carbon and other published data from literature.

Study of factors affecting a combustion method for determining carbon in lithium hydride

International Nuclear Information System (INIS)

Barringer, R.E.; Thornton, R.E.

1975-09-01

An investigation has been made of the factors affecting a combustion method for the determination of low levels (300 to 15,000 micrograms/gram) of carbon in highly reactive lithium hydride. Optimization of the procedure with available equipment yielded recoveries of 90 percent, with a limit of error (0.95) of +-39 percent relative for aliquants containing 35 to 55 micrograms of carbon (500 to 800 micrograms of carbon per gram of lithium hydride sample). Sample preparation, thermal decomposition of the hydride, final ignition of the carbon, and carbon-measurement steps were studied, and a detailed procedure was developed. (auth)

Visualization of flowing current in braided carbon fiber reinforced plastics using SQUID gradiometer for nondestructive evaluation

International Nuclear Information System (INIS)

Hatsukade, Y; Yoshida, K; Kage, T; Tanaka, S; Takai, Y; Aly-Hassan, M S; Hamada, H; Nakai, A

2013-01-01

In this paper, visualization of flowing current in various braided carbon fiber reinforced plastics (CFRPs) was demonstrated using high-temperature superconductor (HTS) superconducting quantum interference device (SQUID) gradiometer, in order to study electrical properties and integrity of the braided CFRP samples. Step-by-step tensile loading was also applied to the samples, in order to study their mechanical properties and destructive mechanism. Experimental results indicated that the addition of carbon nano fibers and middle-end carbon fiber bundles attributed to modify not only the mechanical properties, but also the electrical properties of the samples. Combining the results by the both methods, a scenario of the destructive mechanism of one sample was estimated.

Mg2+ in the major groove modulates B-DNA structure and dynamics.

Directory of Open Access Journals (Sweden)

Marc Guéroult

Full Text Available This study investigates the effect of Mg(2+ bound to the DNA major groove on DNA structure and dynamics. The analysis of a comprehensive dataset of B-DNA crystallographic structures shows that divalent cations are preferentially located in the DNA major groove where they interact with successive bases of (A/GpG and the phosphate group of 5'-CpA or TpG. Based on this knowledge, molecular dynamics simulations were carried out on a DNA oligomer without or with Mg(2+ close to an ApG step. These simulations showed that the hydrated Mg(2+ forms a stable intra-strand cross-link between the two purines in solution. ApG generates an electrostatic potential in the major groove that is particularly attractive for cations; its intrinsic conformation is well-adapted to the formation of water-mediated hydrogen bonds with Mg(2+. The binding of Mg(2+ modulates the behavior of the 5'-neighboring step by increasing the BII (ε-ζ>0° population of its phosphate group. Additional electrostatic interactions between the 5'-phosphate group and Mg(2+ strengthen both the DNA-cation binding and the BII character of the 5'-step. Cation binding in the major groove may therefore locally influence the DNA conformational landscape, suggesting a possible avenue for better understanding how strong DNA distortions can be stabilized in protein-DNA complexes.

Carbon Deposition during CO₂ Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

DEFF Research Database (Denmark)

Skafte, Theis Løye; Graves, Christopher R.; Blennow, P.

2015-01-01

the onset of carbon deposition. The outlet gas composition at each current step was estimated based on the inlet gas composition and the reactant conversion using Faraday's law. The increase in voltage was observed at lower outlet pCO/pCO2 ratios than that corresponding to the expected thermodynamic......The carbon formation threshold in an operating cell was investigated during electrolysis of an idealized reactant atmosphere of CO and CO2. The electrolysis current was gradually increased in steps until the cell voltage spontaneously increased, thereby indicating cell degradation and possibly...

The emergence and early evolution of biological carbon-fixation.

Science.gov (United States)

Braakman, Rogier; Smith, Eric

2012-01-01

The fixation of CO₂ into living matter sustains all life on Earth, and embeds the biosphere within geochemistry. The six known chemical pathways used by extant organisms for this function are recognized to have overlaps, but their evolution is incompletely understood. Here we reconstruct the complete early evolutionary history of biological carbon-fixation, relating all modern pathways to a single ancestral form. We find that innovations in carbon-fixation were the foundation for most major early divergences in the tree of life. These findings are based on a novel method that fully integrates metabolic and phylogenetic constraints. Comparing gene-profiles across the metabolic cores of deep-branching organisms and requiring that they are capable of synthesizing all their biomass components leads to the surprising conclusion that the most common form for deep-branching autotrophic carbon-fixation combines two disconnected sub-networks, each supplying carbon to distinct biomass components. One of these is a linear folate-based pathway of CO₂ reduction previously only recognized as a fixation route in the complete Wood-Ljungdahl pathway, but which more generally may exclude the final step of synthesizing acetyl-CoA. Using metabolic constraints we then reconstruct a "phylometabolic" tree with a high degree of parsimony that traces the evolution of complete carbon-fixation pathways, and has a clear structure down to the root. This tree requires few instances of lateral gene transfer or convergence, and instead suggests a simple evolutionary dynamic in which all divergences have primary environmental causes. Energy optimization and oxygen toxicity are the two strongest forces of selection. The root of this tree combines the reductive citric acid cycle and the Wood-Ljungdahl pathway into a single connected network. This linked network lacks the selective optimization of modern fixation pathways but its redundancy leads to a more robust topology, making it more

The emergence and early evolution of biological carbon-fixation.

Directory of Open Access Journals (Sweden)

Rogier Braakman

Full Text Available The fixation of CO₂ into living matter sustains all life on Earth, and embeds the biosphere within geochemistry. The six known chemical pathways used by extant organisms for this function are recognized to have overlaps, but their evolution is incompletely understood. Here we reconstruct the complete early evolutionary history of biological carbon-fixation, relating all modern pathways to a single ancestral form. We find that innovations in carbon-fixation were the foundation for most major early divergences in the tree of life. These findings are based on a novel method that fully integrates metabolic and phylogenetic constraints. Comparing gene-profiles across the metabolic cores of deep-branching organisms and requiring that they are capable of synthesizing all their biomass components leads to the surprising conclusion that the most common form for deep-branching autotrophic carbon-fixation combines two disconnected sub-networks, each supplying carbon to distinct biomass components. One of these is a linear folate-based pathway of CO₂ reduction previously only recognized as a fixation route in the complete Wood-Ljungdahl pathway, but which more generally may exclude the final step of synthesizing acetyl-CoA. Using metabolic constraints we then reconstruct a "phylometabolic" tree with a high degree of parsimony that traces the evolution of complete carbon-fixation pathways, and has a clear structure down to the root. This tree requires few instances of lateral gene transfer or convergence, and instead suggests a simple evolutionary dynamic in which all divergences have primary environmental causes. Energy optimization and oxygen toxicity are the two strongest forces of selection. The root of this tree combines the reductive citric acid cycle and the Wood-Ljungdahl pathway into a single connected network. This linked network lacks the selective optimization of modern fixation pathways but its redundancy leads to a more robust topology

Simulating demand for innovative radiotherapies: An illustrative model based on carbon ion and proton radiotherapy

International Nuclear Information System (INIS)

Pommier, Pascal; Lievens, Yolande; Feschet, Fabien; Borras, Josep M.; Baron, Marie Helene; Shtiliyanova, Anastasiya; Pijls-Johannesma, Madelon

2010-01-01

Background and purpose: Innovative therapies are not only characterized by major uncertainties regarding clinical benefit and cost but also the expected recruitment of patients. An original model was developed to simulate patient recruitment to a costly particle therapy by varying layout of the facility and patient referral (one vs. several countries) and by weighting the treated indication by the expected benefit of particle therapy. Material and methods: A multi-step probabilistic spatial model was used to allocate patients to the optimal treatment strategy and facility taking into account the estimated therapeutic gain from the new therapy for each tumour type, the geographical accessibility of the facilities and patient preference. Recruitment was simulated under different assumptions relating to the demand and supply. Results: Extending the recruitment area, reducing treatment capacity, equipping all treatment rooms with a carbon ion gantry and inclusion of proton protocols in carbon ion facilities led to an increased proportion of indications with the highest expected benefit. Assuming the existence of a competing carbon ions facility, lower values of therapeutic gain, and a greater unwillingness of patients to travel for treatment increased the proportion of indications with low expected benefit. Conclusions: Modelling patient recruitment may aid decision-making when planning new and expensive treatments.

Puncture-Healing Thermoplastic Resin Carbon-Fiber-Reinforced Composites

Science.gov (United States)

Gordon, Keith L. (Inventor); Siochi, Emilie J. (Inventor); Grimsley, Brian W. (Inventor); Cano, Roberto J. (Inventor); Czabaj, Michael W. (Inventor)

2015-01-01

A composite comprising a combination of a self-healing polymer matrix and a carbon fiber reinforcement is described. In one embodiment, the matrix is a polybutadiene graft copolymer matrix, such as polybutadiene graft copolymer comprising poly(butadiene)-graft-poly(methyl acrylate-co-acrylonitrile). A method of fabricating the composite is also described, comprising the steps of manufacturing a pre-impregnated unidirectional carbon fiber preform by wetting a plurality of carbon fibers with a solution, the solution comprising a self-healing polymer and a solvent, and curing the preform. A method of repairing a structure made from the composite of the invention is described. A novel prepreg material used to manufacture the composite of the invention is described.

Three decadal inputs of total organic carbon from four major coastal river basins to the summer hypoxic zone of the Northern Gulf of Mexico.

Science.gov (United States)

He, Songjie; Xu, Y Jun

2015-01-15

This study investigated long-term (1980-2009) yields and variability of total organic carbon (TOC) from four major coastal rivers in Louisiana entering the Northern Gulf of Mexico where a large-area summer hypoxic zone has been occurring since the middle 1980s. Two of these rivers drain agriculture-intensive (>40%) watersheds, while the other two rivers drain forest-pasture dominated (>50%) watersheds. The study found that these rivers discharged a total of 13.0×10(4)t TOC annually, fluctuating from 5.9×10(4) to 22.8×10(4)t. Seasonally, the rivers showed high TOC yield during the winter and early spring months, corresponding to the seasonal trend of river discharge. While river hydrology controlled TOC yields, land use has played an important role in fluxes, seasonal variations, and characteristics of TOC. The findings fill in a critical information gap of quantity and quality of organic carbon transport from coastal watersheds to one of the world's largest summer hypoxic zones. Copyright © 2014 Elsevier Ltd. All rights reserved.

Method of synthesizing small-diameter carbon nanotubes with electron field emission properties

Science.gov (United States)

Liu, Jie (Inventor); Du, Chunsheng (Inventor); Qian, Cheng (Inventor); Gao, Bo (Inventor); Qiu, Qi (Inventor); Zhou, Otto Z. (Inventor)

2009-01-01

Carbon nanotube material having an outer diameter less than 10 nm and a number of walls less than ten are disclosed. Also disclosed are an electron field emission device including a substrate, an optionally layer of adhesion-promoting layer, and a layer of electron field emission material. The electron field emission material includes a carbon nanotube having a number of concentric graphene shells per tube of from two to ten, an outer diameter from 2 to 8 nm, and a nanotube length greater than 0.1 microns. One method to fabricate carbon nanotubes includes the steps of (a) producing a catalyst containing Fe and Mo supported on MgO powder, (b) using a mixture of hydrogen and carbon containing gas as precursors, and (c) heating the catalyst to a temperature above 950.degree. C. to produce a carbon nanotube. Another method of fabricating an electron field emission cathode includes the steps of (a) synthesizing electron field emission materials containing carbon nanotubes with a number of concentric graphene shells per tube from two to ten, an outer diameter of from 2 to 8 nm, and a length greater than 0.1 microns, (b) dispersing the electron field emission material in a suitable solvent, (c) depositing the electron field emission materials onto a substrate, and (d) annealing the substrate.

In the foot steps of Madame Curie: A cross-case study of female undergraduate physics majors

Science.gov (United States)

Jaladanki, Vani Savithri

Females are disproportionately underrepresented in STEM (science, technology, engineering, and mathematics) majors. Further, the number of females who take physics in college has declined. While female students make up 61% of graduates in biological sciences and 50% in chemistry, the proportion of women completing physics degrees is only 21% (Sawtelle, 2011). In order to improve women's access to science and engineering education, research must focus on personal and environmental factors that motivate them to select these fields (AAUW, 2010). The purpose of this study was to explore how the educational experiences of three female undergraduate physics majors contribute to their current dispositions toward, interest in, and pursuit of physics as a major at a large southern research university. This qualitative study employs symbolic interactionism (Blumer, 1969) as its methodological framework and social cognitive career theory (Lent, Brown, & Hackett, 2002) as its theoretical framework. Case study methods (Yin, 2006) were implemented to investigate the experiences of three participants. The primary sources of data included critical incident interviews (Flanagan, 1954), photographs, documents, object elicitations, and the researcher's reflections. Narrative and arts-based techniques were employed to analyze and represent data. Findings are presented as co-constructed narratives of the participants' journeys to becoming undergraduate physics majors. Three major themes emerged from the cross case analysis: carving new spaces, authoring an empowered self, and show me you care and so will I. The direct experiences of engaging with science at a young age and social persuasions of family members, teachers, and peers strongly influenced the participants' interest in and pursuit of physics. Their current dispositions to physics result from vicarious experiences with professors and peers in combination with the social persuasions of the latter. This study informs science

N-Doped carbon spheres with hierarchical micropore-nanosheet networks for high performance supercapacitors.

Science.gov (United States)

Wang, Shoupei; Zhang, Jianan; Shang, Pei; Li, Yuanyuan; Chen, Zhimin; Xu, Qun

2014-10-18

N-doped carbon spheres with hierarchical micropore-nanosheet networks (HPSCSs) were facilely fabricated by a one-step carbonization and activation process of N containing polymer spheres by KOH. With the synergy effect of the multiple structures, HPSCSs exhibit a very high specific capacitance of 407.9 F g(-1) at 1 mV s(-1) (1.2 times higher than that of porous carbon spheres) and a robust cycling stability for supercapacitors.

Synthesis and carbonization chemistry of a phosphorous-nitrogen based intumescent flame retardant

Energy Technology Data Exchange (ETDEWEB)

Ma, Haiyun, E-mail: mahaiyun@gmail.com [College of Chemistry and Environmental Science, HeBei University, Baoding, Hebei Province 071002 (China); Fang, Zhengping [MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou 310027 (China); Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, Zhejiang University, Ningbo 315100 (China)

2012-09-10

Graphical abstract: The carbonization chemistry and mechanism of a novel synthesized intumescent flame retardant. The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture. Highlights: Black-Right-Pointing-Pointer The IFR synthesized is polymeric and has high molecular weight. Black-Right-Pointing-Pointer The IFR has a higher thermal stability than most of the commercial IFRs. Black-Right-Pointing-Pointer The final chars of IFR showed a complex P-O-Ph and aromatic/graphitic structure. - Abstract: In this work, a polymeric phosphorous-nitrogen containing intumescent flame retardant, named poly(diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB), was synthesized. The carbonization chemistry was investigated. FTIR and {sup 1}H NMR were used to confirm the chemical structure of PDSPB. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), in situ FTIR and energy dispersive X-ray (EDX) were used to investigate and monitor the chemical structural changes during thermal degradation. PDSPB demonstrated a three-step degradation behavior. PDSPB oligomers continuously polymerized and generated a higher macromolecular weight during the first step (200-250 Degree-Sign C). The phosphate ester bonds were broken down and phosphoric acid was released which dehydrated the carbon source to form chars during the second step (280-320 Degree-Sign C). The residues will be further degraded and form final chars during the final weight loss step (400-450 Degree-Sign C). The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture.

Synthesis and carbonization chemistry of a phosphorous–nitrogen based intumescent flame retardant

International Nuclear Information System (INIS)

Ma, Haiyun; Fang, Zhengping

2012-01-01

Graphical abstract: The carbonization chemistry and mechanism of a novel synthesized intumescent flame retardant. The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture. Highlights: ► The IFR synthesized is polymeric and has high molecular weight. ► The IFR has a higher thermal stability than most of the commercial IFRs. ► The final chars of IFR showed a complex P-O-Ph and aromatic/graphitic structure. - Abstract: In this work, a polymeric phosphorous–nitrogen containing intumescent flame retardant, named poly(diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB), was synthesized. The carbonization chemistry was investigated. FTIR and 1 H NMR were used to confirm the chemical structure of PDSPB. Thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), in situ FTIR and energy dispersive X-ray (EDX) were used to investigate and monitor the chemical structural changes during thermal degradation. PDSPB demonstrated a three-step degradation behavior. PDSPB oligomers continuously polymerized and generated a higher macromolecular weight during the first step (200–250 °C). The phosphate ester bonds were broken down and phosphoric acid was released which dehydrated the carbon source to form chars during the second step (280–320 °C). The residues will be further degraded and form final chars during the final weight loss step (400–450 °C). The final chars showed a complex P-O-Ph and aromatic/graphitic structure containing architecture.

Applicability of Activated Carbon to Treatment of Waste Containing Iodine-Labeled Compounds

International Nuclear Information System (INIS)

Gad, H.M.H.; El-Mouhty, N.R.A.; Aly, H.F.

2008-01-01

The applicability of activated carbon prepared from sawdust (SD) by one-step chemical activation process using H 3 PO 4 (H) to treatment of aqueous waste contaminated with iodine-labeled prolactin (I-PRL) has been investigated. Treatment processes were performed under the varying conditions; contact time, temperature, carbon type, carbon dosage, and different particle size of activated carbon (SDH). Effect of aqueous waste volume has been investigated to calculate the batch factor (V/M) and the distribution coefficient (K d ). The used activated carbon (SDH) was characterized by N 2 adsorption, FTIR, density, ph, point of zero charge ph p zc, moisture and ash content. Methylene blue (MB) and iodine number was calculated by adsorption from solution. In order to investigate the mechanism of sorption and potential rate controlling steps, pseudo first- and second-order equations, intra particle diffusion equation and the Elovich equation have been used to test experimental data. Kinetic analysis of the four models has been carried out for system variables in order to assess which model provides the best fit predicted data with experimental results. 7 M NaOH can be used for regeneration of spent SDH activated carbon with the efficiency of 99.6% and the regenerated carbon can be reused for five cycles effectively. The prospect of applying the SDH activated carbon prepared from agricultural by-product, sawdust, to treatment of aqueous waste contaminated with I-PRL appears promising and is considered highly applicable because of its high adsorption capacity, available at low cost, easily regenerated and reused

Studies on Preparation and Characterization of Aluminum Nitride-Coated Carbon Fibers and Thermal Conductivity of Epoxy Matrix Composites

Directory of Open Access Journals (Sweden)

Hyeon-Hye Kim

2017-08-01

Full Text Available In this work; the effects of an aluminum nitride (AlN ceramic coating on the thermal conductivity of carbon fiber-reinforced composites were studied. AlN were synthesized by a wet-thermal treatment (WTT method in the presence of copper catalysts. The WTT method was carried out in a horizontal tube furnace at above 1500 °C under an ammonia (NH3 gas atmosphere balanced by a nitrogen using aluminum chloride as a precursor. Copper catalysts pre-doped enhance the interfacial bonding of the AlN with the carbon fiber surfaces. They also help to introduce AlN bonds by interrupting aluminum oxide (Al2O3 formation in combination with oxygen. Scanning electron microscopy (SEM; Transmission electron microscopy (TEM; and X-ray diffraction (XRD were used to analyze the carbon fiber surfaces and structures at each step (copper-coating step and AlN formation step. In conclusion; we have demonstrated a synthesis route for preparing an AlN coating on the carbon fiber surfaces in the presence of a metallic catalyst.

CT-Guided Percutaneous Step-by-Step Radiofrequency Ablation for the Treatment of Carcinoma in the Caudate Lobe

Science.gov (United States)

Dong, Jun; Li, Wang; Zeng, Qi; Li, Sheng; Gong, Xiao; Shen, Lujun; Mao, Siyue; Dong, Annan; Wu, Peihong

2015-01-01

Abstract The location of the caudate lobe and its complex anatomy make caudate lobectomy and radiofrequency ablation (RFA) under ultrasound guidance technically challenging. The objective of the exploratory study was to introduce a novel modality of treatment of lesions in caudate lobe and discuss all details with our experiences to make this novel treatment modality repeatable and educational. The study enrolled 39 patients with liver caudate lobe tumor first diagnosed by computerized tomography (CT) or magnetic resonance imaging (MRI). After consultation of multi-disciplinary team, 7 patients with hepatic caudate lobe lesions were enrolled and accepted CT-guided percutaneous step-by-step RFA treatment. A total of 8 caudate lobe lesions of the 7 patients were treated by RFA in 6 cases and RFA combined with percutaneous ethanol injection (PEI) in 1 case. Median tumor diameter was 29 mm (range, 18–69 mm). A right approach was selected for 6 patients and a dorsal approach for 1 patient. Median operative time was 64 min (range, 59–102 min). Median blood loss was 10 mL (range, 8-16 mL) and mainly due to puncture injury. Median hospitalization time was 4 days (range, 2–5 days). All lesions were completely ablated (8/8; 100%) and no recurrence at the site of previous RFA was observed during median 8 months follow-up (range 3–11 months). No major or life-threatening complications or deaths occurred. In conclusion, percutaneous step-by-step RFA under CT guidance is a novel and effective minimally invasive therapy for hepatic caudate lobe lesions with well repeatability. PMID:26426638

Reviewing the Carbonation Resistance of Concrete

Directory of Open Access Journals (Sweden)

S P Singh

2016-07-01

Full Text Available The paper reviews the studies on one of the important durability properties of concrete i.e. Carbonation. One of the main causes of deterioration of concrete is carbonation, which occurs when carbon dioxide (CO2 penetrates the concrete’s porous system to create an environment with lower pH around the reinforcement in which corrosion can proceed. Carbonation is a major cause of degradation of concrete structures leading to expensive maintenance and conservation operations. Herein, the importance, process and effect of various parameters such as water/cement ratio, water/binder ratio, curing conditions, concrete cover, super plasticizers, type of aggregates, grade of concrete, porosity, contaminants, compaction, gas permeability, supplementary cementitious materials (SCMs/ admixtures on the carbonation of concrete has been reviewed. Various methods for estimating the carbonation depth are also reported briefly

Hydrogen with intrinsic CO{sub 2} sequestration: the ENI 'One Step Hydrogen' process

Energy Technology Data Exchange (ETDEWEB)

Rossini, S.; Cornaro, U.; Mizia, F.; Malandrino, A.; Piccoli, V. [Enitecnologie SpA, S. Donata Milanese (Italy); Sanfilippo, D.; Miracca, I. [Snamprogetti SpA, S. Donato Milanese (Italy)

2003-07-01

The new process, under development in our companies, is aimed to hydrogen production with intrinsic carbon dioxide sequestration. This is made possible combining in a cycle the water oxidative potential with a reverse action by a reducing agent like hydrocarbons, the preferred being natural gas. In the first step a suitable oxide takes up the oxygen from water splitting producing hydrogen. The solid act as an oxygen storage medium. Such 'lattice' oxygen is in turn released through one or more elemental steps. The process fits very well with a circulating fluid bed reactor which allows the movement of the solid from one reactive environment to the other. (orig.)

Spectroscopic studies of carbon containing molecules and their break-up in PISCES-A

International Nuclear Information System (INIS)

Pospieszczyk, A.; Ra, Y.; Hirooka, Y.; Conn, R.W.; Goebel, D.M.; LaBombard, B.; Nygren, R.E.

1989-12-01

We have used the PISCES-A facility in order to study the behavior of carbon containing molecules in a representative plasma with parameters close to that of a tokamak boundary layer, CH 4 , C 2 H 2 , C 2 H 4 , CO, and CO 2 molecules were introduced through a slit aperture into a helium plasma and the radiation from these due to electronic excitation was spectrographically recorded. The imaging of the plasma onto the entrance slit of a 1.33m McPherson optical spectrometer was chosen in such a way that simultaneous information about spectral and spatial distribution of the emission could be obtained by an attached photographic camera and an optical multichannel analyser (OMA). The recorded spectra show that many features in previously obtained spectra from limiters originate -- beside from hydrocarbons -- from carbonoxides, which seem to play a major role in the transport of carbon and oxygen. It was also possible to calibrate the radiation intensity of several molecular bands versus the known molecular influx so that an absolute determination of these fluxes from the wall of a fusion device could be done. Measurements of the attenuation of the individual species were carried out, which describe the penetration of carbon, oxygen, and hydrogen atoms into a discharge by taking into account individual steps in the molecular breakup process. 36 refs., 35 figs

Dynamic carbon content as an indicator of desertification processes in soils developed from volcanic parental material in the Region of Murcia

International Nuclear Information System (INIS)

Martinez-Martinez, S.; Faz Cano, A.; Acosta Aviles, J. A.

2009-01-01

Soil Organic Carbon (SOC is an essential components of the global carbon cycle, especially in soils developed from volcanic rocks, due to these soils does not have inorganic carbon. In arid and semiarid areas mineralization of organic carbon is very intense due to climatic conditions, causing soils depletion and therefore desertification. The objective of this study is to determine the content of OC, as a first step in the assessment of desertification. The objective of this study is to determine the content of OC, as a first step in the assessment of desertification processes affecting this area of the southeast of Spain. (Author) 7 refs.

Amphibious fluorescent carbon dots: one-step green synthesis and application for light-emitting polymer nanocomposites.

Science.gov (United States)

Zhou, Li; He, Benzhao; Huang, Jiachang

2013-09-21

A facile and green approach for the synthesis of amphibious fluorescent carbon dots (CDs) from natural polysaccharide is reported. Light-emitting polymer nanocomposites with excellent optical performance can be easily prepared by incorporation of the amphibious CDs into the polymer matrix.

Carbon sequestration research and development

Energy Technology Data Exchange (ETDEWEB)

Reichle, Dave; Houghton, John; Kane, Bob; Ekmann, Jim; and others

1999-12-31

Predictions of global energy use in the next century suggest a continued increase in carbon emissions and rising concentrations of carbon dioxide (CO{sub 2}) in the atmosphere unless major changes are made in the way we produce and use energy--in particular, how we manage carbon. For example, the Intergovernmental Panel on Climate Change (IPCC) predicts in its 1995 ''business as usual'' energy scenario that future global emissions of CO{sub 2} to the atmosphere will increase from 7.4 billion tonnes of carbon (GtC) per year in 1997 to approximately 26 GtC/year by 2100. IPCC also projects a doubling of atmospheric CO{sub 2} concentration by the middle of next century and growing rates of increase beyond. Although the effects of increased CO{sub 2} levels on global climate are uncertain, many scientists agree that a doubling of atmospheric CO{sub 2} concentrations could have a variety of serious environmental consequences. The goal of this report is to identify key areas for research and development (R&D) that could lead to an understanding of the potential for future use of carbon sequestration as a major tool for managing carbon emissions. Under the leadership of DOE, researchers from universities, industry, other government agencies, and DOE national laboratories were brought together to develop the technical basis for conceiving a science and technology road map. That effort has resulted in this report, which develops much of the information needed for the road map.

Uranium and sulphate values from carbonate leach process

International Nuclear Information System (INIS)

Berger, B.

1983-01-01

The process concerns the recovery of uraniferous and sulphur values from liquor resulting from the attack of sulphur containing uraniferous ores by an alkaline solution of sodium carbonate and/or bicarbonate. Ammonia is introduced into the liquor to convert any HCO 3 - to CO 3 2- . The neutralised liquor from this step is then contacted with an anion exchange resin to fix the uranium and sulphate ions, leaving a liquor containing ammonia, sodium carbonate and/or bicarbonate in solution. Uranium and sulphate ions are eluted with an ammonia carbonate and/or bicarbonate solution to yield a solution of ammonium uranyl carbonate complex and ammonium sulphate. The solution is subjected to thermal treatment until a suspension of precipitated ammonium uranate and/or diuranate is obtained in a solution of the ammonium sulphate. Carbon dioxide, ammonia and water vapor are driven off. The precipitated ammonium uranate and/or diuranate is then separated from the solution of ammonium sulphate and the precipitate is calcined to yield uranium trioxide and ammonia

Structure–mechanical property relationship in a high strength low carbon alloy steel processed by two-step intercritical annealing and intercritical tempering

Energy Technology Data Exchange (ETDEWEB)

Zhou, W.H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Wang, X.L. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Venkatsurya, P.K.C. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Guo, H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Shang, C.J., E-mail: cjshang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States)

2014-06-01

The influence of annealing and tempering temperature on the microstructure and mechanical properties was investigated in a low carbon alloy steel that was processed by a two-step intercritical annealing and intercritical tempering heat treatment. In general, the microstructure of the processed steel comprises intercritical lath-like ferrite, bainitic/martensitic lath and acicular-type retained austenite. The lower intercritical annealing temperature resulted in lower fraction of intercritical ferrite with finer grain size and consequently higher strength. On the other hand, the intercritical tempering temperature significantly influenced retained austenite content and precipitation. High fraction of retained austenite was obtained at a temperature slightly above Ac{sub 1} temperature and retained austenite content decreased with increase in tempering temperature. This behavior is attributed to the competition between the enrichment of Mn and Ni and the fraction of reversed austenite. Fine niobium carbide precipitates of size ∼2–6 nm and copper precipitates of size range ∼10–30 nm were obtained. The optimal intercritical annealing and tempering temperatures to obtain the product of tensile strength and elongation % of ∼30 GPa% were 780 °C and 660 °C, respectively and the volume fraction of retained austenite was ∼29%.

The Value of Step-by-Step Risk Assessment for Unmanned Aircraft

DEFF Research Database (Denmark)

La Cour-Harbo, Anders

2018-01-01

The new European legislation expected in 2018 or 2019 will introduce a step-by-step process for conducting risk assessments for unmanned aircraft flight operations. This is a relatively simple approach to a very complex challenge. This work compares this step-by-step process to high fidelity risk...... modeling, and shows that at least for a series of example flight missions there is reasonable agreement between the two very different methods....

Flexible and conductive waste tire-derived carbon/polymer composite paper as pseudocapacitive electrode

Science.gov (United States)

Naskar, Amit K.; Paranthaman, Mariappan Parans; Boota, Muhammad; Gogotsi, Yury

2018-04-10

A method of making a supercapacitor from waste tires, includes the steps of providing rubber pieces and contacting the rubber pieces with a sulfonation bath to produce sulfonated rubber; pyrolyzing the sulfonated rubber to produce a tire-derived carbon composite comprising carbon black embedded in rubber-derived carbon matrix comprising graphitized interface portions; activating the tire-derived carbon composite by contacting the tire-derived carbon composite with a specific surface area-increasing composition to increase the specific surface area of the carbon composite to provide an activated tire-derived carbon composite; and, mixing the activated tire-derived carbon composite with a monomer and polymerizing the monomer to produce a redox-active polymer coated, activated tire-derived carbon composite. The redox-active polymer coated, activated tire-derived carbon composite can be formed into a film. An electrode and a supercapacitor are also disclosed.

Functionalization of carbon nanotubes with silver clusters

International Nuclear Information System (INIS)

Cveticanin, Jelena; Krkljes, Aleksandra; Kacarevic-Popovic, Zorica; Mitric, Miodrag; Rakocevic, Zlatko; Trpkov, Djordje; Neskovic, Olivera

2010-01-01

In this paper, an advanced method of one-step functionalization of single and multi walled carbon nanotubes (SWCNTs and MWCNTs) using γ-irradiation was described. Two synthesis procedures, related with different reduction species, were employed. For the first time, poly(vinyl alcohol) PVA is successfully utilized as a source to reduce silver (Ag) metal ions without having any additional reducing agents to obtain Ag nanoparticles on CNTs. The decoration of carbon nanotubes with Ag nanoparticles takes place through anchoring of (PVA) on nanotube's surface. Optical properties of as-prepared samples and mechanism responsible for the functionalization of carbon nanotubes were investigated using UV-vis and FTIR spectroscopy, respectively. Decorated carbon nanotubes were visualized using microscopic techniques: transmission electron microscopy and scanning tunneling microscopy. Also, the presence of Ag on the nanotubes was confirmed using energy dispersive X-ray spectroscopy. This simple and effective method of making a carbon nanotube type of composites is of interest not only for an application in various areas of technology and biology, but for investigation of the potential of radiation technology for nanoengineering of materials.

Pyrolytic 3D Carbon Microelectrodes for Electrochemistry

DEFF Research Database (Denmark)

Hemanth, Suhith; Caviglia, Claudia; Amato, Letizia

2016-01-01

This work presents the fabrication and characterization of suspended three-dimensional (3D) pyrolytic carbon microelectrodes for electrochemical applications. For this purpose, an optimized process with multiple steps of UV photolithography with the negative tone photoresist SU-8 followed...... by pyrolysis at 900ºC for 1h was developed. With this process, microelectrode chips with a three electrode configuration were fabricated and characterized with cyclic voltammetry (CV) using a 10mM potassium ferri-ferrocyanide redox probe in a custom made batch system with magnetic clamping. The 3D pyrolytic...... carbon microelectrodes displayed twice the higher peak current compared to 2D....

Sorption of organic compounds to activated carbons. Evaluation of isotherm models

NARCIS (Netherlands)

Pikaar, I.; Koelmans, A.A.; Noort, van P.C.M.

2006-01-01

Sorption to 'hard carbon' (black carbon, coal, kerogen) in soils and sediments is of major importance for risk assessment of organic pollutants. We argue that activated carbon (AC) may be considered a model sorbent for hard carbon. Here, we evaluate six sorption models on a literature dataset for

Making carbon sequestration a paying proposition

Science.gov (United States)

Han, Fengxiang X.; Lindner, Jeff S.; Wang, Chuji

2007-03-01

Atmospheric carbon dioxide (CO2) has increased from a preindustrial concentration of about 280 ppm to about 367 ppm at present. The increase has closely followed the increase in CO2 emissions from the use of fossil fuels. Global warming caused by increasing amounts of greenhouse gases in the atmosphere is the major environmental challenge for the 21st century. Reducing worldwide emissions of CO2 requires multiple mitigation pathways, including reductions in energy consumption, more efficient use of available energy, the application of renewable energy sources, and sequestration. Sequestration is a major tool for managing carbon emissions. In a majority of cases CO2 is viewed as waste to be disposed; however, with advanced technology, carbon sequestration can become a value-added proposition. There are a number of potential opportunities that render sequestration economically viable. In this study, we review these most economically promising opportunities and pathways of carbon sequestration, including reforestation, best agricultural production, housing and furniture, enhanced oil recovery, coalbed methane (CBM), and CO2 hydrates. Many of these terrestrial and geological sequestration opportunities are expected to provide a direct economic benefit over that obtained by merely reducing the atmospheric CO2 loading. Sequestration opportunities in 11 states of the Southeast and South Central United States are discussed. Among the most promising methods for the region include reforestation and CBM. The annual forest carbon sink in this region is estimated to be 76 Tg C/year, which would amount to an expenditure of 11.1-13.9 billion/year. Best management practices could enhance carbon sequestration by 53.9 Tg C/year, accounting for 9.3% of current total annual regional greenhouse gas emission in the next 20 years. Annual carbon storage in housing, furniture, and other wood products in 1998 was estimated to be 13.9 Tg C in the region. Other sequestration options

Mechanism of SO2 removal by carbon

Science.gov (United States)

Lizzio, Anthony A.; DeBarr, Joseph A.

1997-01-01

The reaction of SO2 with carbon (C) in the presence of O2 and H2O involves a series of reactions that leads to the formation of sulfuric acid as the final product. The rate-determining step in the overall process is the oxidation of SO2 to SO3. Three SO2 oxidation reactions are possible. Adsorbed SO2 (C−SO2) can react either with gas phase O2 or with adsorbed oxygen (C−O complex) to form sulfur trioxide (SO3), or gas phase SO2 can react directly with the C−O complex. In optimizing the SO2 removal capabilities of carbon, most studies only assume a given mechanism for SO2 adsorption and conversion to H2SO4 to be operable. The appropriate SO2 oxidation step and role of the C−O complex in this mechanism remain to be determined. The ultimate goal of this study was to prepare activated char from Illinois coal with optimal properties for low-temperature (80−150°C) removal of sulfur dioxide from coal combustion flue gas. The SO2 adsorption capacity of activated char was found to be inversely proportional to the amount of oxygen adsorbed on its surface. A temperature-programmed desorption technique was developed to titrate those sites responsible for adsorption of SO2 and conversion to H2SO4. On the basis of these results, a mechanism for SO2 removal by carbon was proposed. The derived rate expression showed SO2 adsorption to be dependent only on the fundamental rate constant and concentration of carbon atoms designated as free sites. Recent studies indicate a similar relationship exists between the rate of carbon gasification (in CO2 or H2O) and the number of reactive sites as determined by transient kinetics experiments. Utilizing the concept of active or free sites, it was possible to produce a char from Illinois coal having an SO2 adsorption capacity surpassing that of a commercial catalytic activated carbon.

Highly regenerable carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres as oxygen reduction electrocatalyst and magnetic adsorbent

Energy Technology Data Exchange (ETDEWEB)

Zhou, Wenqiang [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China); School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Liu, Minmin; Cai, Chao [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China); Zhou, Haijun, E-mail: zhouhaijun@just.edu.cn [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Liu, Rui, E-mail: ruiliu@tongji.edu.cn [Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, and Institute for Advanced Study, Tongji University, Shanghai 201804 (China)

2017-02-15

We present the synthesis and multifunctional utilization of core-satellite carbon-Fe{sub 3}O{sub 4} nanoparticles to serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. Starting from polydopamine (PDA) nanoparticles and Fe(NO{sub 3}){sub 3}, carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The synergistic combination of Fe{sub 3}O{sub 4} and N-doped carbon endows the nanocomposite with high electrochemical activity in ORR and mainly four electrons transferred in reaction process. Furthermore, carbon-Fe{sub 3}O{sub 4} nanoparticles used as magnetic adsorbent exhibit the efficient removal of Rhodamine B from an aqueous solution. The recovery and reuse of the adsorbent is demonstrated 5 times without any detectible loss in activity. - Graphical abstract: Starting from polydopamine (PDA) nanoparticles and Fe(NO{sub 3}){sub 3}, carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. The nanocomposites serve as the enabling platform for a range of applications including oxygen reduction reaction (ORR) and magnetic adsorbent. - Highlights: • Carbon-Fe{sub 3}O{sub 4} core–satellite nanospheres are synthesized through successive steps of impregnation, ammoniation and carbonization. • Polydopamine and Fe(NO{sub 3}){sub 3} are precursors for N-doped carbon source and Fe{sub 3}O{sub 4} nanoparticles, respectively. • The nanocomposites exhibit high electrochemical activity in ORR. • The nanocomposites effectively adsorb organic dyes with magnetic recovery and good recycle property.

Preparation of mesoporous carbon from fructose using zinc-based activators

Directory of Open Access Journals (Sweden)

Tutik Setianingsih

2015-07-01

Full Text Available Mesoporous carbons were synthesized from fructose using activators of zinc silicate (ZS, zinc borate (ZB, and zinc borosilicate (ZBS. The synthesis involves 3 steps, including caramelization of sugar, carbonization of caramel, and washing of carbon to separate the activator from the carbon. The solid products were characterized by N2 gas adsorption-desorption, X-ray diffraction, FTIR spectrophotometry, and Transmission Electron Microscopy. The pore characterizations of the carbons indicate that in ZBS system, ZB may have the role as mesopore size controller, whereas silica component may improve porosity created by ZB without changing the size. This role of ZB may be connected to it’s performance as catalyst of caramelization and it’s crystalinity, as supported by measurement of caramel intermediete and characterization of the activators with X-ray diffraction. The infrared spectra confirms that the carbons’s surfaces have C=O, C-O, and O-H functional groups. The XRD patterns of the carbons show that all activators create the turbotratic carbons.

Supercapacitance of Single-Walled Carbon Nanotubes-Polypyrrole Composites

Directory of Open Access Journals (Sweden)

Matei Raicopol

2013-01-01

Full Text Available The composites based on carbon nanotubes (CNTs and conducting polymers (CPs are promising materials for supercapacitor devices due to their unique nanostructure that combines the large pseudocapacitance of the CPs with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the CNTs. Here, we report a new electrochemical method to obtain polypyrrole (PPY/single-walled carbon nanotube (SWCNT composites. In the first step, the SWCNTs are covalently functionalized with monomeric units of pyrrole by esterification of acyl chloride functionalized SWCNTs and N-(6-hydroxyhexylpyrrole. In the second step, the PPY/SWCNTs composites are obtained by copolymerizing the pyrrole monomer with the pyrrole units grafted on SWCNTs surface using controlled potential electrolysis. The composites were further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed good electrochemical charge storage properties for the synthesized composites based on PPY and SWCNTs covalently functionalized with pyrrole units making them promising electrode materials for high power supercapacitors.

Impact of the 2015 El Niño on the Indonesian carbon balance: implications for carbon mitigation

Science.gov (United States)

Bowman, K. W.; Liu, J.; Bloom, A. A.; Parazoo, N.; Lee, M.; Walker, T. W.; Menemenlis, D.; Jiang, Z.; Gierach, M.; Gurney, K. R.

2016-12-01

The COP21 or Paris Agreement in Dec. 2015 was a landmark step in a cooperative approach to reduce anthropogenic emissions from both fossil fuel and deforestation. During that same period, one of the strongest El Niños on record led to devastating droughts, fires, and air pollution in Indonesia. We assess the impact of this El Niño on the Indonesia carbon balance using the NASA Carbon Monitoring System Flux (CMS-Flux) pilot project, which assimilates satellite observations across the entire carbon cycle to attribute the CO2 growth rate to spatially resolved surface fluxes. We assimilate new xCO2 observations from the Orbital Carbon Observatory (OCO-2) to quantify net carbon fluxes and validate those fluxes against independent in-situ atmospheric data. The contribution of biomass burning to the carbon balance is independently determined from the assimilation of Measurements of Pollution in the Troposphere (MOPITT). The impact of the concomitant drought on productively is assessed from the assimilation of new solar induced fluorescence (SIF) measurements. Using these multiple lines of evidence, we investigate the relative role of biomass burning and productivity in the contribution of Indonesia to the global atmospheric growth rate. The exceptionally long turnover rates of peat carbon pools lead to effectively irreversible carbon loss to the atmosphere. The implications of these losses to Indonesian Intended Nationally Determined Contributions (INDC) as part of the Paris agreement will be explored.

A one-step carbonization route towards nitrogen-doped porous carbon hollow spheres with ultrahigh nitrogen content for CO 2 adsorption

KAUST Repository

Wang, Yu

2015-01-01

© The Royal Society of Chemistry 2015. Nitrogen doped porous carbon hollow spheres (N-PCHSs) with an ultrahigh nitrogen content of 15.9 wt% and a high surface area of 775 m² g^-1 were prepared using Melamine-formaldehyde nanospheres as hard templates and nitrogen sources. The N-PCHSs were completely characterized and were found to exhibit considerable CO2 adsorption performance (4.42 mmol g^-1).

Step-by-Step Visual Manuals: Design and Development

Science.gov (United States)

Urata, Toshiyuki

2004-01-01

The types of handouts and manuals that are used in technology training vary. Some describe procedures in a narrative way without graphics; some employ step-by-step instructions with screen captures. According to Thirlway (1994), a training manual should be like a tutor that permits a student to learn at his own pace and gives him confidence for…

Carbon Dioxide Capture by Deep Eutectic Solvent Impregnated Sea Mango Activated Carbon

Science.gov (United States)

Zulkurnai, N. Z.; Ali, U. F. Md.; Ibrahim, N.; Manan, N. S. Abdul

2018-03-01

The increment amount of the CO2 emission by years has become a major concern worldwide due to the global warming issue. However, the influence modification of activated carbon (AC) has given a huge revolution in CO2 adsorption capture compare to the unmodified AC. In the present study, the Deep Eutectic Solvent (DES) modified surface AC was used for Carbon Dioxide (CO2) capture in the fixed-bed column. The AC underwent pre-carbonization and carbonization processes at 519.8 °C, respectively, with flowing of CO2 gas and then followed by impregnation with 53.75% phosphoric acid (H3PO4) at 1:2 precursor-to-activant ratios. The prepared AC known as sea mango activated carbon (SMAC) was impregnated with DES at 1:2 solid-to-liquid ratio. The DES is composing of choline chloride and urea with ratio 1:2 choline chloride to urea. The optimum adsorption capacity of SMAC was 33.46 mgco2/gsol and 39.40 mgco2/gsol for DES modified AC (DESAC).

Ocean carbon uptake and storage

International Nuclear Information System (INIS)

Tilbrook, Bronte

2007-01-01

Full text: The ocean contains about 95% of the carbon in the atmosphere, ocean and land biosphere system, and is of fundamental importance in regulating atmospheric carbon dioxide concentrations. In the 1990s an international research effort involving Australia was established to determine the uptake and storage of anthropogenic C02 for all major ocean basins. The research showed that about 118 of the 244 + 20 billion tons of the anthropogenic carbon emitted through fossil fuel burning and cement production has been stored in the ocean since preindustrial times, thus helping reduce the rate of increase in atmospheric C02. The research also showed the terrestrial biosphere has been a small net source of C02 (39 ± 28 billion tons carbon) to the atmosphere over the same period. About 60% of the total ocean inventory of the anthropogenic C02 was found in the Southern Hemisphere, with most in the 30 0 S to 50 0 S latitude band. This mid-latitude band is where surface waters are subducted as Mode and Intermediate waters, which is a major pathway controlling ocean C02 uptake. High storage (23% of the total) also occurs in the North Atlantic, associated with deep water formation in that basin. The ocean uptake and storage is expected to increase in the coming decades as atmospheric C02 concentrations rise. However, a number of feedback mechanisms associated with surface warming, changes in circulation, and biological effects are likely to impact on the uptake capacity. The accumulation or storage-of the C02 in the ocean is also the major driver of ocean acidification with potential to disrupt marine ecosystems. This talk will describe the current understanding of the ocean C02 uptake and storage and a new international research strategy to detect how the ocean uptake and storage will evolve on interannual through decadal scales. Understanding the ocean response to increasing atmospheric C02 will be a key element in managing future C02 increases and establishing

THEODORE, a two-step heating system for the EC/OC determination of radiocarbon (14C) in the environment

International Nuclear Information System (INIS)

Szidat, S.; Jenk, T.M.; Gaeggeler, H.W.; Synal, H.-A.; Hajdas, I.; Bonani, G.; Saurer, M.

2004-01-01

Measurements of 14 C in the organic carbon (OC) and elemental carbon (EC) fractions, respectively, of fine aerosol particles bear the potential to apportion anthropogenic and biogenic emission sources. For this purpose, the system THEODORE (two-step heating system for the EC/OC determination of radiocarbon in the environment) was developed. In this device, OC and EC are transformed into carbon dioxide in a stream of oxygen at 340 and 650 deg. C, respectively, and reduced to filamentous carbon. This is the target material for subsequent accelerator mass spectrometry (AMS) 14 C measurements, which were performed on sub-milligram carbon samples at the PSI/ETH compact 500 kV AMS system. Quality assurance measurements of SRM 1649a, Urban Dust, yielded a fraction of modern f M in total carbon (TC) of 0.522 ± 0.018 (n=5, 95% confidence level) in agreement with reported values. The results for OC and EC are 0.70 ± 0.05 (n=3) and 0.066 ± 0.020 (n=4), respectively

Aircraft de-icer: Recycling can cut carbon emissions in half

International Nuclear Information System (INIS)

Johnson, Eric P.

2012-01-01

Flight-safety regulations in most countries require aircraft to be ice-free upon takeoff. In icy weather, this means that the aircraft usually must be de-iced (existing ice is removed) and sometimes anti-iced (to protect against ice-reformation). For both processes, aircraft typically are sprayed with an ‘antifreeze’ solution, consisting mainly of glycol diluted with water. This de/anti-icing creates an impact on the environment, of which environmental regulators have grown increasingly conscious. The US Environmental Protection Agency (EPA), for example, recently introduced stricter rules that require airports above minimum size to collect de-icing effluents and send them to wastewater treatment. De-icer collection and treatment is already done at most major airports, but a few have gone one step further: rather than putting the effluent to wastewater, they recycle it. This study examines the carbon savings that can be achieved by recycling de-icer. There are two key findings. One, recycling, as opposed to not recycling, cuts the footprint of aircraft de-icing by 40–50% — and even more, in regions where electricity-generation is cleaner. Two, recycling petrochemical-based de-icer generates a 15–30% lower footprint than using ‘bio’ de-icer without recycling. - Highlights: ► Carbon footprint of aircraft de-icing can be measured. ► Recycling aircraft de-icer cuts the footprint of aircraft de-icing by 40–50%. ► Recycling ‘fossil’ de-icer is lower carbon than not recycling ‘bio’ de-icer.

Characterization and electrochemical application of carbon materials based on poly(phenylene oxide)

Science.gov (United States)

Gray, Hunter

Carbon materials possess excellent electrical and surface properties for the next generation of energy storage devices. Polymers provide a carbon rich and tailorable precursor for the production of carbon materials. Therefore, activated carbons were prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) via a three step process: thermal oxidation, carbonization, and activation with KOH. The activated carbons are predominately microporous with BET specific surface areas up to 2638 m2/g. Impedance spectroscopy revealed these carbons possess electrical conductivities comparable to commercial carbon blacks and consequently were employed in thin-film composite electrodes in electrochemical double-layer capacitors. Cyclic voltammetry confirmed maximum specific capacitances of 13.23 F/g and 2.848 F/g for aqueous and organic electrolyte systems, respectively. Additionally, carbon nanotubes were synthesized from PPO and other polymers with a nickel catalyst via chemical vapor deposition as revealed by transmission electron microscopy. This is the first report of carbon nanotubes produced from PPO.

Effect of amino acid-functionalized multi-walled carbon nanotubes ...

Indian Academy of Sciences (India)

In a single-step, rapid microwave-assisted process, multi-walled carbon nanotubes were functionalized by -valine amino acid. Formation of amino acid on nanotube surface was confirmed by Fourier transform-infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, field emission scanning and transmission ...

Performance of an attention-demanding task during treadmill walking shifts the noise qualities of step-to-step variation in step width.

Science.gov (United States)

Grabiner, Mark D; Marone, Jane R; Wyatt, Marilynn; Sessoms, Pinata; Kaufman, Kenton R

2018-06-01

The fractal scaling evident in the step-to-step fluctuations of stepping-related time series reflects, to some degree, neuromotor noise. The primary purpose of this study was to determine the extent to which the fractal scaling of step width, step width and step width variability are affected by performance of an attention-demanding task. We hypothesized that the attention-demanding task would shift the structure of the step width time series toward white, uncorrelated noise. Subjects performed two 10-min treadmill walking trials, a control trial of undisturbed walking and a trial during which they performed a mental arithmetic/texting task. Motion capture data was converted to step width time series, the fractal scaling of which were determined from their power spectra. Fractal scaling decreased by 22% during the texting condition (p Step width and step width variability increased 19% and five percent, respectively (p step width fractal scaling. The change of the fractal scaling of step width is consistent with increased cognitive demand and suggests a transition in the characteristics of the signal noise. This may reflect an important advance toward the understanding of the manner in which neuromotor noise contributes to some types of falls. However, further investigation of the repeatability of the results, the sensitivity of the results to progressive increases in cognitive load imposed by attention-demanding tasks, and the extent to which the results can be generalized to the gait of older adults seems warranted. Copyright © 2018 Elsevier B.V. All rights reserved.

Carbon dioxide utilization in a microalga-based biorefinery: Efficiency of carbon removal and economic performance under carbon taxation.

Science.gov (United States)

Wiesberg, Igor Lapenda; Brigagão, George Victor; de Medeiros, José Luiz; de Queiroz Fernandes Araújo, Ofélia

2017-12-01

Coal-fired power plants are major stationary sources of carbon dioxide and environmental constraints demand technologies for abatement. Although Carbon Capture and Storage is the most mature route, it poses severe economic penalty to power generation. Alternatively, this penalty is potentially reduced by Carbon Capture and Utilization, which converts carbon dioxide to valuable products, monetizing it. This work evaluates a route consisting of carbon dioxide bio-capture by Chlorella pyrenoidosa and use of the resulting biomass as feedstock to a microalgae-based biorefinery; Carbon Capture and Storage route is evaluated as a reference technology. The integrated arrangement comprises: (a) carbon dioxide biocapture in a photobioreactor, (b) oil extraction from part of the produced biomass, (b) gasification of remaining biomass to obtain bio-syngas, and (c) conversion of bio-syngas to methanol. Calculation of capital and operational expenditures are estimated based on mass and energy balances obtained by process simulation for both routes (Carbon Capture and Storage and the biorefinery). Capital expenditure for the biorefinery is higher by a factor of 6.7, while operational expenditure is lower by a factor of 0.45 and revenues occur only for this route, with a ratio revenue/operational expenditure of 1.6. The photobioreactor is responsible for one fifth of the biorefinery capital expenditure, with footprint of about 1000 ha, posing the most significant barrier for technical and economic feasibility of the proposed biorefinery. The Biorefinery and Carbon Capture and Storage routes show carbon dioxide capture efficiency of 73% and 48%, respectively, with capture cost of 139$/t and 304$/t. Additionally, the biorefinery has superior performance in all evaluated metrics of environmental impacts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Carbonation by fluid-rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

Science.gov (United States)

Piccoli, Francesca; Vitale Brovarone, Alberto; Beyssac, Olivier; Martinez, Isabelle; Ague, Jay J.; Chaduteau, Carine

2016-07-01

Carbonate-bearing lithologies are the main carbon carrier into subduction zones. Their evolution during metamorphism largely controls the fate of carbon, regulating its fluxes between shallow and deep reservoirs. Recent estimates predict that almost all subducted carbon is transferred into the crust and lithospheric mantle during subduction metamorphism via decarbonation and dissolution reactions at high-pressure conditions. Here we report the occurrence of eclogite-facies marbles associated with metasomatic systems in Alpine Corsica (France). The occurrence of these marbles along major fluid-conduits as well as textural, geochemical and isotopic data indicating fluid-mineral reactions are compelling evidence for the precipitation of these carbonate-rich assemblages from carbonic fluids during metamorphism. The discovery of metasomatic marbles brings new insights into the fate of carbonic fluids formed in subducting slabs. We infer that rock carbonation can occur at high-pressure conditions by either vein-injection or chemical replacement mechanisms. This indicates that carbonic fluids produced by decarbonation reactions and carbonate dissolution may not be directly transferred to the mantle wedge, but can interact with slab and mantle-forming rocks. Rock-carbonation by fluid-rock interactions may have an important impact on the residence time of carbon and oxygen in subduction zones and lithospheric mantle reservoirs as well as carbonate isotopic signatures in subduction zones. Furthermore, carbonation may modulate the emission of CO2 at volcanic arcs over geological time scales.

Springtime carbon emission episodes at the Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles

Directory of Open Access Journals (Sweden)

J. Jung

2011-11-01

Full Text Available In order to investigate the emission of carbonaceous aerosols at the Gosan background super-site (33.17° N, 126.10° E in East Asia, total suspended particles (TSP were collected during spring of 2007 and 2008 and analyzed for particulate organic carbon, elemental carbon, total carbon (TC, total nitrogen (TN, and stable carbon isotopic composition (δ¹³C of TC. The stable carbon isotopic composition of TC (δ¹³C_TC was found to be lowest during pollen emission episodes (range: −26.2‰ to −23.5‰, avg. −25.2 ± 0.9‰, approaching those of the airborne pollen (−28.0‰ collected at the Gosan site. Based on a carbon isotope mass balance equation, we found that ~42% of TC in the TSP samples during the pollen episodes was attributed to airborne pollen from Japanese cedar trees planted around tangerine farms in Jeju Island. A negative correlation between the citric acid-carbon/TC ratios and δ¹³C_TC was obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollen and then transported to the Gosan site. Thermal evolution patterns of organic carbon during the pollen episodes were characterized by high OC evolution in the OC2 temperature step (450 °C. Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols and the effect of aging of organic aerosols during the long-range atmospheric transport and sources of organic aerosols.

Effect of ocean acidification on the benthic foraminifera Ammonia sp. is caused by a decrease in carbonate ion concentration

Directory of Open Access Journals (Sweden)

N. Keul

2013-10-01

Full Text Available About 30% of the anthropogenically released CO2 is taken up by the oceans; such uptake causes surface ocean pH to decrease and is commonly referred to as ocean acidification (OA. Foraminifera are one of the most abundant groups of marine calcifiers, estimated to precipitate ca. 50 % of biogenic calcium carbonate in the open oceans. We have compiled the state of the art literature on OA effects on foraminifera, because the majority of OA research on this group was published within the last three years. Disparate responses of this important group of marine calcifiers to OA were reported, highlighting the importance of a process-based understanding of OA effects on foraminifera. We cultured the benthic foraminifer Ammonia sp. under a range of carbonate chemistry manipulation treatments to identify the parameter of the carbonate system causing the observed effects. This parameter identification is the first step towards a process-based understanding. We argue that [CO32−] is the parameter affecting foraminiferal size-normalized weights (SNWs and growth rates. Based on the presented data, we can confirm the strong potential of Ammonia sp. foraminiferal SNW as a [CO32−] proxy.

Microwave-assisted ionothermal synthesis of nanostructured anatase titanium dioxide/activated carbon composite as electrode material for capacitive deionization

International Nuclear Information System (INIS)

Liu, Po-I; Chung, Li-Ching; Shao, Hsin; Liang, Teh-Ming; Horng, Ren-Yang; Ma, Chen-Chi M.; Chang, Min-Chao

2013-01-01

The nanostructured anatase titanium dioxide/activated carbon composite material for capacitive deionization electrode was prepared in a short time by a lower temperature two-step microwave-assisted ionothermal (sol–gel method in the presence of ionic liquid) synthesis method. This method includes a reaction and a crystallization step. In the crystallization step, the ionic liquid plays a hydrothermal analogy role in driving the surface anatase crystallization of amorphous titanium dioxide nanoparticles formed in the reaction step. The energy dispersive spectroscopic study of the composite indicates that the anatase titanium dioxide nanoparticles are evenly deposited in the matrix of activated carbon. The electrochemical property of the composite electrode was investigated. In comparison to the pristine activated carbon electrode, higher specific capacitance was observed for the nanostructured anatase titanium dioxide/activated carbon composite electrode, especially when the composite was prepared with a molar ratio of titanium tetraisopropoxide/H 2 O equal to 1:15. Its X-ray photoelectron spectroscopic result indicates that it has the highest amount of Ti-OH. The Ti-OH group can enhance the wetting ability and the specific capacitance of the composite electrode. The accompanying capacitive deionization result indicates that the decay of electrosorption capacity of this composite electrode is insignificant after five cycle tests. It means that the ion electrosorption–desorption becomes a reversible process

Paris and its long-term temperature goal: First steps on a long road

Science.gov (United States)

Rogelj, J.

2017-12-01

As a means to achieve its long-term temperature goal, the Paris Agreement put in place a system of regularly updated country pledges alternating with global stocktaking exercises that assess progress towards achieving the Paris goals. By now, the vast majority of countries have submitted their intended actions (also known as Nationally Determined Contributions - NDCs). This begs the question what these amount to and whether they are in line with the agreement`s long-term temperature goal. A structured sensitivity analysis of the emissions implications of the Paris pledges has been carried out, showing that the ambiguity and imprecision of the NDCs leaves open a wide range of possible outcomes by 2030. This range has important implications for the feasibility and cost of pathways that attempt to limit warming to the temperature goals of the Agreement. We identify salient steps to reduce the overall uncertainty, and explore the minimum requirements that have to be met for integrated energy-economy-land models to still find options to stay within the temperature limits of the Paris Agreement. These requirements come under the form of near-term emissions reductions, and assumptions about the deployment of carbon-dioxide removal technologies in the second half of the century.

One step shift towards flexible supercapacitors based on carbon nanotubes - A review

Science.gov (United States)

Yar, A.; Dennis, J. O.; Mohamed, N. M.; Mumtaz, A.; Irshad, M. I.; Ahmad, F.

2014-10-01

Supercapacitors have emerged as prominent energy storage devices that offer high energy density compared to conventional capacitors and high power density which is not found in batteries. Carbon nanotubes (CNTs) because of their high surface area and tremendous electrical properties are used as electrode material for supercapacitors. In this review we focused on the factors like surface area, role of the electrolyte and techniques adopted to improve performance of CNTs based supercapacitors. The supercapacitors are widely tested in liquid electrolytes which are normally hazardous in nature, toxic, flammable and their leakage has safety concerns. This review also focuses on research which is replacing these unsafe electrolytes by solid electrolytes with the combination of low cost CNTs deposited flexible supports for supercapacitors.

One step shift towards flexible supercapacitors based on carbon nanotubes - A review

Energy Technology Data Exchange (ETDEWEB)

Yar, A., E-mail: asfandyarhargan@gmail.com, E-mail: johndennis@petronas.com.my, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: asad-032@yahoo.com, E-mail: imrancssp@gmail.com; Dennis, J. O., E-mail: asfandyarhargan@gmail.com, E-mail: johndennis@petronas.com.my, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: asad-032@yahoo.com, E-mail: imrancssp@gmail.com; Mohamed, N. M., E-mail: asfandyarhargan@gmail.com, E-mail: johndennis@petronas.com.my, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: asad-032@yahoo.com, E-mail: imrancssp@gmail.com; Mumtaz, A., E-mail: asfandyarhargan@gmail.com, E-mail: johndennis@petronas.com.my, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: asad-032@yahoo.com, E-mail: imrancssp@gmail.com; Irshad, M. I., E-mail: asfandyarhargan@gmail.com, E-mail: johndennis@petronas.com.my, E-mail: noranimuti-mohamed@petronas.com.my, E-mail: asad-032@yahoo.com, E-mail: imrancssp@gmail.com [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia); Ahmad, F., E-mail: ahmad-1234farooq@yahoo.com [Department of Electrical and Electronic Engineering, Universiti Teknologi PETRONAS (Malaysia)

2014-10-24

Supercapacitors have emerged as prominent energy storage devices that offer high energy density compared to conventional capacitors and high power density which is not found in batteries. Carbon nanotubes (CNTs) because of their high surface area and tremendous electrical properties are used as electrode material for supercapacitors. In this review we focused on the factors like surface area, role of the electrolyte and techniques adopted to improve performance of CNTs based supercapacitors. The supercapacitors are widely tested in liquid electrolytes which are normally hazardous in nature, toxic, flammable and their leakage has safety concerns. This review also focuses on research which is replacing these unsafe electrolytes by solid electrolytes with the combination of low cost CNTs deposited flexible supports for supercapacitors.

One step shift towards flexible supercapacitors based on carbon nanotubes - A review

International Nuclear Information System (INIS)

Yar, A.; Dennis, J. O.; Mohamed, N. M.; Mumtaz, A.; Irshad, M. I.; Ahmad, F.

2014-01-01

Supercapacitors have emerged as prominent energy storage devices that offer high energy density compared to conventional capacitors and high power density which is not found in batteries. Carbon nanotubes (CNTs) because of their high surface area and tremendous electrical properties are used as electrode material for supercapacitors. In this review we focused on the factors like surface area, role of the electrolyte and techniques adopted to improve performance of CNTs based supercapacitors. The supercapacitors are widely tested in liquid electrolytes which are normally hazardous in nature, toxic, flammable and their leakage has safety concerns. This review also focuses on research which is replacing these unsafe electrolytes by solid electrolytes with the combination of low cost CNTs deposited flexible supports for supercapacitors

Structures of adsorbed CO on atomically smooth and on stepped sngle crystal surfaces

International Nuclear Information System (INIS)

Madey, T.E.; Houston, J.E.

1980-01-01

The structures of molecular CO adsorbed on atomically smooth surfaces and on surfaces containing monatomic steps have been studied using the electron stimulated desorption ion angular distribution (ESDIAD) method. For CO adsorbed on the close packed Ru(001) and W(110) surfaces, the dominant bonding mode is via the carbon atom, with the CO molecular axis perpendicular to the plane of the surface. For CO on atomicaly rough Pd(210), and for CO adsorbed at step sites on four different surfaces vicinal to W(110), the axis of the molecule is tilted or inclined away from the normal to the surface. The ESDIAD method, in which ion desorption angles are related to surface bond angles, provides a direct determination of the structures of adsorbed molecules and molecular complexes on surfaces

Hydrogenation of surface carbon on alumina-supported nickel

Energy Technology Data Exchange (ETDEWEB)

Mccarthy, J.G.; Wise, H.

1979-05-01

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

Effect of One-Step and Multi-Steps Polishing System on Enamel Roughness

Directory of Open Access Journals (Sweden)

Cynthia Sumali

2013-07-01

Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The final procedures of orthodontic treatment are bracket debonding and cleaning the remaining adhesive. Multi-step polishing system is the most common method used. The disadvantage of that system is long working time, because of the stages that should be done. Therefore, dental material manufacturer make an improvement to the system, to reduce several stages into one stage only. This new system is known as one-step polishing system. Objective: To compare the effect of one-step and multi-step polishing system on enamel roughness after orthodontic bracket debonding. Methods: Randomized control trial was conducted included twenty-eight maxillary premolar randomized into two polishing system; one-step OptraPol (Ivoclar, Vivadent and multi-step AstroPol (Ivoclar, Vivadent. After bracket debonding, the remaining adhesive on each group was cleaned by subjective polishing system for ninety seconds using low speed handpiece. The enamel roughness was subjected to profilometer, registering two roughness parameters (Ra, Rz. Independent t-test was used to analyze the mean score of enamel roughness in each group. Results: There was no significant difference of enamel roughness between one-step and multi-step polishing system (p>0.005. Conclusion: One-step polishing system can produce a similar enamel roughness to multi-step polishing system after bracket debonding and adhesive cleaning.DOI: 10.14693/jdi.v19i3.136

Electrochemical study of nitrobenzene reduction using novel Pt nanoparticles/macroporous carbon hybrid nanocomposites

International Nuclear Information System (INIS)

Zhang Yufan; Zeng Lijun; Bo Xiangjie; Wang Huan; Guo Liping

2012-01-01

Graphical abstract: A one-step microwave-assisted route for rapidly synthesizing Pt nanoparticles ensemble on macroporous carbon hybrid nanocomposites (PNMPC) has been reported. As a novel electrode material, the excellent electrochemical behavior of nitrobenzene was investigated thoroughly at the PNMPC modified glassy carbon electrode. And moreover, the modified electrode was successfully applied to the determination of nitrobenzene in real samples. Highlights: ► One-step microwave-assisted heating synthesis Pt nanoparticles/macroporous carbon hybrid nanocomposites (PNMPC). ► Catalytic rate constant being 3.14 × 10 4 M −1 s −1 for NB in pH 7.0. ► Sensitive electrochemical detection of NB at the PNMPC/Nafion/GC electrode. ► The electrode showing excellent anti-interference ability and good stability for NB. - Abstract: Novel Pt nanoparticles (PN) ensemble on macroporous carbon (MPC) hybrid nanocomposites (PNMPC) were prepared through a rapidly and simple one-step microwave-assisted heating procedure. The obtained PNMPC was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and electrochemical methods. The electrochemical reduction of nitrobenzene (NB) was thoroughly investigated at the PNMPC modified glassy carbon (GC) electrode, and the catalytic rate constant was calculated to be 3.14 × 10 4 M −1 s −1 for NB. A sensitive NB sensor was developed based on the PNMPC/GC electrode, which showed a wide linear range (1–200 μM), low detection limit (50 nM), high sensitivity (6.93 μA μM −1 ), excellent anti-interference ability and good stability. And moreover, the electrode was successfully applied to the determination of NB in real samples.

Condiment-Derived 3D Architecture Porous Carbon for Electrochemical Supercapacitors.

Science.gov (United States)

Qian, Wenjing; Zhu, Jingyue; Zhang, Ye; Wu, Xiao; Yan, Feng

2015-10-07

The one-step synthesis of porous carbon nanoflakes possessing a 3D texture is achieved by cooking (carbonization) a mixture containing two condiments, sodium glutamate (SG) and sodium chloride, which are commonly used in kitchens. The prepared 3D porous carbons are composed of interconnected carbon nanoflakes and possess instinct heteroatom doping such as nitrogen and oxygen, which furnishes the electrochemical activity. The combination of micropores and mesopores with 3D configurations facilitates persistent and fast ion transport and shorten diffusion pathways for high-performance supercapacitor applications. Sodium glutamate carbonized at 800 °C exhibits high charge storage capacity with a specific capacitance of 320 F g(-1) in 6 m KOH at a current density of 1 A g(-1) and good stability over 10,000 cycles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Minimal features of a computer and its basic software to executs NEPTUNIX 2 numerical step

International Nuclear Information System (INIS)

Roux, Pierre.

1982-12-01

NEPTUNIX 2 is a package which carries out the simulation of complex processes described by numerous non linear algebro-differential equations. Main features are: non linear or time dependent parameters, implicit form, stiff systems, dynamic change of equations leading to discontinuities on some variables. Thus the mathematical model is built with an equation set F(x,x',t,l) = 0, where t is the independent variable, x' the derivative of x and l an ''algebrized'' logical variable. The NEPTUNIX 2 package is divided into two successive major steps: a non numerical step and a numerical step. The non numerical step must be executed on a series 370 IBM computer or a compatible computer. This step generates a FORTRAN language model picture fitted for the computer carrying out the numerical step. The numerical step consists in building and running a mathematical model simulator. This execution step of NEPTUNIX 2 has been designed in order to be transportable on many computers. The present manual describes minimal features of such host computer used for executing the NEPTUNIX 2 numerical step [fr

Interaction of chemokines with their receptors--from initial chemokine binding to receptor activating steps

DEFF Research Database (Denmark)

Thiele, Stefanie; Rosenkilde, Mette Marie

2014-01-01

and surveillance. Chemokines are a group of 8-12 kDa large peptides with a secondary structure consisting of a flexible N-terminus and a core-domain usually stabilized by two conserved disulfide bridges. They mainly interact with the extracellular domains of their cognate 7TM receptors. Affinityand activity......-contributing interactions are attributed to different domains and known to occur in two steps. Here, knowledge on chemokine and receptor domains involved in the first binding-step and the second activation-step is reviewed. A mechanism comprising at least two steps seems consistent; however, several intermediate...... interactions possibly occur, resulting in a multi-step process, as recently proposed for other 7TM receptors. Overall, the N-terminus of chemokine receptors is pivotal for binding of all chemokines. During receptor activation, differences between the two major chemokine subgroups occur, as CC-chemokines mainly...

Microsoft® Visual Basic® 2010 Step by Step

CERN Document Server

Halvorson, Michael

2010-01-01

Your hands-on, step-by-step guide to learning Visual Basic® 2010. Teach yourself the essential tools and techniques for Visual Basic® 2010-one step at a time. No matter what your skill level, you'll find the practical guidance and examples you need to start building professional applications for Windows® and the Web. Discover how to: Work in the Microsoft® Visual Studio® 2010 Integrated Development Environment (IDE)Master essential techniques-from managing data and variables to using inheritance and dialog boxesCreate professional-looking UIs; add visual effects and print supportBuild com

Improving the corrosion resistance of proton exchange membrane fuel cell carbon supports by pentafluorophenyl surface functionalization

Science.gov (United States)

Forouzandeh, Farisa; Li, Xiaoan; Banham, Dustin W.; Feng, Fangxia; Joseph Kakanat, Abraham; Ye, Siyu; Birss, Viola

2018-02-01

In this study, the effect of surface functionalization on the electrochemical corrosion resistance of a high surface area, mesoporous colloid imprinted carbon powder (CIC), as well as microporous Vulcan carbon (VC, serving as the benchmark), was demonstrated, primarily for PEM fuel cell applications. CIC-22, which is highly hydrophilic and was synthesized with 22 nm silica colloid templates, and as-received, mildly hydrophobic, VC powders, were functionalized with 2,3,4,5,6-pentafluorophenyl (-PhF5) surface groups using a straightforward diazonium reduction reaction. These carbons were then subjected to corrosion testing, involving a potential cycling-step sequence in room temperature 0.5 M H2SO4. Using cyclic voltammetry and charge/time analysis, the double layer and pseudo-capacitive gravimetric charges of the carbons, prior to and after the application of these potential steps, were tracked in order to obtain information about surface area changes and the extent of carbon oxidation, respectively. It is shown that the corrosion resistance was improved by ca. 50-80% by surface functionalization, likely due to a combination of surface passivation (loss of carbon active sites) and increased surface hydrophobicity.