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Sample records for 2mw direct carbonate

  1. Power conversion and quality of the Santa Clara 2 MW direct carbonate fuel cell demonstration plant

    Skok, A.J. [Fuel Cell Engineering Corp., Danbury, CT (United States); Abueg, R.Z. [Basic Measuring Instruments, Santa Clara, CA (United States); Schwartz, P. [Fluor Daniel, Inc., Irvine, CA (United States)] [and others

    1996-12-31

    The Santa Clara Demonstration Project (SCDP) is the first application of a commercial-scale carbonate fuel cell power plant on a US electric utility system. It is also the largest fuel cell power plant ever operated in the United States. The 2MW plant, located in Santa Clara, California, utilizes carbonate fuel cell technology developed by Energy Research Corporation (ERC) of Danbury, Connecticut. The ultimate goal of a fuel cell power plant is to deliver usable power into an electrical distribution system. The power conversion sub-system does this for the Santa Clara Demonstration Plant. A description of this sub-system and its capabilities follows. The sub-system has demonstrated the capability to deliver real power, reactive power and to absorb reactive power on a utility grid. The sub-system can be operated in the same manner as a conventional rotating generator except with enhanced capabilities for reactive power. Measurements demonstrated the power quality from the plant in various operating modes was high quality utility grade power.

  2. Startup, testing, and operation of the Santa Clara 2MW direct carbonate fuel cell demonstration plant

    Skok, A.J.; Leo, A.J. [Fuel Cell Engineering Corp., Danbury, CT (United States); O`Shea, T.P. [Santa Clara Demonstration Project, CA (United States)

    1996-12-31

    The Santa Clara Demonstration Project (SCDP) is a collaboration between several utility organizations, Fuel Cell Engineering Corporation (FCE), and the U.S. Dept. Of Energy aimed at the demonstration of Energy Research Corporation`s (ERC) direct carbonate fuel cell (DFC) technology. ERC has been pursuing the development of the DFC for commercialization near the end of this decade, and this project is an integral part of the ERC commercialization effort. The objective of the Santa Clara Demonstration Project is to provide the first full, commercial scale demonstration of this technology. The approach ERC has taken in the commercialization of the DFC is described in detail elsewhere. An aggressive core technology development program is in place which is focused by ongoing interaction with customers and vendors to optimize the design of the commercial power plant. ERC has selected a 2.85 MW power plant unit for initial market entry. Two ERC subsidiaries are supporting the commercialization effort: the Fuel Cell Manufacturing Corporation (FCMC) and the Fuel Cell Engineering Corporation (FCE). FCMC manufactures carbonate stacks and multi-stack modules, currently from its production facility in Torrington, CT. FCE is responsible for power plant design, integration of all subsystems, sales/marketing, and client services. FCE is serving as the prime contractor for the design, construction, and testing of the SCDP Plant. FCMC has manufactured the multi-stack submodules used in the DC power section of the plant. Fluor Daniel Inc. (FDI) served as the architect-engineer subcontractor for the design and construction of the plant and provided support to the design of the multi-stack submodules. FDI is also assisting the ERC companies in commercial power plant design.

  3. Design of 2 MW Permanent Magnet Double Stator Generator Direct-Driven by Wind Turbine%2MW双定子直驱永磁同步风力发电机的设计

    刘婷; 黄守道; 欧阳红林

    2012-01-01

    The direct drive wind power generator operates at low speed with a larger size and large number of poles, and it accounts for a large space. Double stator PMSG( permanent magnet synchronous generator) with the rated power of 2 MW which was driven directly without gear system was designed. Comparative study of the performance both of no load and rated load with single stator PMSG was studied based on FEA( Finite Element Analysis). The results show that the design is reasonable. Compared with the 2 MW single stator permanent magnet wind power generator, double stator PMSG can get good performance and reduce the weight and volume of the generator, which has good reference value.%根据直驱风力发电机级数多、转速低、体积大的特点,设计了额定功率2 MW的双定子直驱式永磁同步风力发电机,并通过电磁场有限元分析软件对所设计发电机进行了空载和额定负载情况下的仿真研究,验证了设计方案的可行.并与同功率的单定子永磁发电机相比,双定子永磁同步风力发电机性能良好,同时可以减轻重量,并有效提高电机的空间利用率,对双定子复合式风力发电机的设计具有一定的参考价值.

  4. INTEGRATED GASIFICATION COMBINED CYCLE PROJECT 2 MW FUEL CELL DEMONSTRATION

    FuelCell Energy

    2005-05-16

    With about 50% of power generation in the United States derived from coal and projections indicating that coal will continue to be the primary fuel for power generation in the next two decades, the Department of Energy (DOE) Clean Coal Technology Demonstration Program (CCTDP) has been conducted since 1985 to develop innovative, environmentally friendly processes for the world energy market place. The 2 MW Fuel Cell Demonstration was part of the Kentucky Pioneer Energy (KPE) Integrated Gasification Combined Cycle (IGCC) project selected by DOE under Round Five of the Clean Coal Technology Demonstration Program. The participant in the CCTDP V Project was Kentucky Pioneer Energy for the IGCC plant. FuelCell Energy, Inc. (FCE), under subcontract to KPE, was responsible for the design, construction and operation of the 2 MW fuel cell power plant. Duke Fluor Daniel provided engineering design and procurement support for the balance-of-plant skids. Colt Engineering Corporation provided engineering design, fabrication and procurement of the syngas processing skids. Jacobs Applied Technology provided the fabrication of the fuel cell module vessels. Wabash River Energy Ltd (WREL) provided the test site. The 2 MW fuel cell power plant utilizes FuelCell Energy's Direct Fuel Cell (DFC) technology, which is based on the internally reforming carbonate fuel cell. This plant is capable of operating on coal-derived syngas as well as natural gas. Prior testing (1992) of a subscale 20 kW carbonate fuel cell stack at the Louisiana Gasification Technology Inc. (LGTI) site using the Dow/Destec gasification plant indicated that operation on coal derived gas provided normal performance and stable operation. Duke Fluor Daniel and FuelCell Energy developed a commercial plant design for the 2 MW fuel cell. The plant was designed to be modular, factory assembled and truck shippable to the site. Five balance-of-plant skids incorporating fuel processing, anode gas oxidation, heat recovery

  5. Dynamic simulation of a direct carbonate fuel cell power plant

    Ernest, J.B. [Fluor Daniel, Inc., Irvine, CA (United States); Ghezel-Ayagh, H.; Kush, A.K. [Fuel Cell Engineering, Danbury, CT (United States)

    1996-12-31

    Fuel Cell Engineering Corporation (FCE) is commercializing a 2.85 MW Direct carbonate Fuel Cell (DFC) power plant. The commercialization sequence has already progressed through construction and operation of the first commercial-scale DFC power plant on a U.S. electric utility, the 2 MW Santa Clara Demonstration Project (SCDP), and the completion of the early phases of a Commercial Plant design. A 400 kW fuel cell stack Test Facility is being built at Energy Research Corporation (ERC), FCE`s parent company, which will be capable of testing commercial-sized fuel cell stacks in an integrated plant configuration. Fluor Daniel, Inc. provided engineering, procurement, and construction services for SCDP and has jointly developed the Commercial Plant design with FCE, focusing on the balance-of-plant (BOP) equipment outside of the fuel cell modules. This paper provides a brief orientation to the dynamic simulation of a fuel cell power plant and the benefits offered.

  6. A 2 MW heating plant supply by farmers

    Nilsson, P.

    1993-12-31

    In Sweden, non-food products are encouraged since 1991, so energetic cultures develop. This paper deals with a Salix plantation and a 2 MW heating plant in Kolback supplied by salix plantations and wood waste. (TEC). 1 fig.

  7. Design of a dummy load for the 2 MW HF transmitter

    A 2 MW transmitter with a frequency ranging from 30 to 60 MHz is used for the KSTAR ICRF heating source and it is necessary to equip it with a dummy load which has a low VSWR above the second or third harmonic frequency for testing the 2 MW transmitter. The resistive film type is well known as a non-inductive dummy load, however it can't be used above 300 kW because of problem at the surface adhesion between the ceramic substrate and the resistive film or sputtered carbon which imposes a limit on the power density of the film resistor. So, above 1 MW the most promising candidate is the soda water dummy load where the soda water plays a role in both the rf power absorbing medium and the cooling water. In this work, the electrical and mechanical design requirements of the 2 MW soda dummy load are introduced and RF characteristics are discussed using a lumped circuit model and a numerical analysis. (author)

  8. Recent Progress of 2MW 140GHz ECRH System on HL-2A

    Lu Z.H.

    2012-09-01

    Full Text Available In order to provide more capability of physics study for high-performance plasma, such as current profile control, neoclassical tearing modes suppression, transport study and so on, a new 2MW/140GHz/3s second-harmonic ECRH system with X-mode injection is on schedule on HL-2A. The total power of this system is 2MW and the pulse duration is 3 sec, which is generated by two gyrotrons manufactured by GYCOM. Two evacuated Φ63.5mm transmission lines were used to propagate these two 1MW/3s wave beams. A fast steerable launcher has been designed and installed on the HL-2A tokamak to inject four beams with narrow beam width and enable continuous beam scanning in toroidal and poloidal directions independently.

  9. Digital, remote control system for a 2-MW research reactor

    Battle, R.E.; Corbett, G.K.

    1988-01-01

    A fault-tolerant programmable logic controller (PLC) and operator workstations have been programmed to replace the hard-wired relay control system in the 2-MW Bulk Shielding Reactor (BSR) at Oak Ridge National Laboratory. In addition to the PLC and remote and local operator workstations, auxiliary systems for remote operation include a video system, an intercom system, and a fiber optic communication system. The remote control station, located at the High Flux Isotope Reactor 2.5 km from the BSR, has the capability of rector startup and power control. The system was designed with reliability and fail-safe features as important considerations. 4 refs., 3 figs.

  10. Development of a 2 MW relativistic backward wave oscillator

    Yaduvendra Choyal; Lalit Gupta; Prasad Deshpande; Krishna Prasad Maheshwari; Kailash Chander Mittal; Suresh Chand Bapna

    2008-12-01

    In this paper, a high power relativistic backward wave oscillator (BWO) experiment is reported. A 230 keV, 2 kA, 150 ns relativistic electron beam is generated using a Marx generator. The beam is then injected into a hollow rippled wall metallic cylindrical tube that forms a slow wave structure. The beam is guided using an axial pulsed magnetic field having a peak value 1 T and duration 1 ms. The field is generated by the discharge of a capacitor bank into a solenoidal coil. A synchronization circuit ensures the generation of the electron beam at the instant when the axial magnetic field attains its peak value. The beam interacts with the SWS modes and generates microwaves due to Cherenkov interaction. Estimated power of 2 MW in TM 01 mode is observed.

  11. Carbon aerogel electrodes for direct energy conversion

    Mayer, S.T.; Kaschmitter, J.L.; Pekala, R.W.

    1997-02-11

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes is described, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome. 1 fig.

  12. Infrared Measurements of the RF Output of 170-GHz/2-MW Coaxial Cavity Gyrotron and Its Phase Retrieval Analysis

    Jawla, S.; Hogge, J.-P.; Alberti, S.; Goodman, T.; Piosczyk, B.; Rzesnicki, T.

    2009-01-01

    We report the experimental results of the infrared measurements of output RF beam of the European 2-MW 170-GHz coaxial cavity gyrotron for ITER. The output beam profile is measured by the infrared thermographic technique using an infrared camera and a target material which is being irradiated by the RF output. The beam intensity was measured at several locations along the propagation direction. The data were processed for noise reduction and perspective correction and then used with the phase...

  13. Carbon dioxide direct cycle modular reactor

    Recently, as the micro gas-turbine power generation is clean for environment and has high convenience, it is focused as a small size dispersion electric source for super markets, hospitals, factories, and so on. And, a modular high temperature gas reactor (PBMR) adopting the gas turbine is also focused recently, and is progressed on its construction in South Africa and reported on construction plan of the Exelon Inc. in U.S.A. PBMR has specific safety for a small size and pebble-bed reactor and also has some characters on low construction cost similar to that of LWR due to simplification and small size module adoption of its plant. The PBMR uses helium for its coolants, of which exit temperature is set for at 900degC to get higher thermal efficiency. This is because of its adoption of Brayton cycle to fast reduce the efficiency with falling temperature. However, as helium is a costly and easy-emission vapor, it is desired to alternate to cheaper and more difficult-emission vapor. Here were introduced on carbon dioxide (CO2) direct cycle using carbon dioxide with extremely higher thermal efficiency than helium and its applicability to nuclear reactors. (G.K.)

  14. Thermal power output determination of 2 MW heat source by using of thermocouples

    Holubcik, Michal; Vician, Peter; Palacka, Matej

    2016-06-01

    Experiment is an operation or procedure carried out under controlled conditions in order to discover an unknown effect or law, to test or establish a hypothesis, or to illustrate a known law. The most important part of the experiment is to evaluate the measured values. Measurement accuracy depends on a number of factors. Deviations of instruments cannot eliminate or influence if it is neglect the possibility of using more precise measuring equipment. Another way for the most accurate results can be calibration. Calibration allows achieve measurement values with relatively high accuracy using less precision instruments. The paper deals about the problematic of thermal power measurement accuracy. Thermal power was measured on heat source with nominal thermal power 2 MW by using direct calorimetric method. There were used ultrasonic flow meter and type K thermocouples. Type K thermocouples are not very suitable for these applications because of their low precision. The paper presents the possibility of using calibrated thermocouples for the thermal power measurement with acceptable accuracy.

  15. Carbon fuel particles used in direct carbon conversion fuel cells

    Cooper, John F.; Cherepy, Nerine

    2012-10-09

    A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

  16. DIII-D electron cyclotron heating 2 MW upgrade project. Final report for the period FY89 through FY97

    The 2 MW, 110 GHz ECH system was based on the General Atomics Proposal to the Department of Energy: DIII-D Fusion Research Program Vol. I Technical, and Vol. II Cost (GACP-72-166, July 1987 and revised). This proposal was reviewed in August 1987 by a senior technical review committee, who recommended to vigorously pursue increasing the ECH power to 6 MW. The realization of the higher frequency and power ECH on DIII-D was recognized by the committee to be important, not only for the DIII-D program, but also for future devices and the whole ECH area. Subsequently, an engineering cost and schedule review was conducted by DOE-OAK which confirmed the GA costs and schedules and recommended proceeding directly to 10 MW. However, because of budgetary constraints, in the April 1988 Field Task Proposal submission, GA proposed a phased ECH approach, Phase I being 2 MW and Phase II increasing the power to 10 MW. After review, DOE instructed GA to initiate the prototype 2 MW, 110 GHz program. The contract to procure four 500 kW, 110 GHz, 10 s gyrotrons from Varian Associates was initiated in April 1989 with final delivery by November 1990. Because of difficulties in spreading the energy of the electron beam over the collector area, the testing of the first gyrotron delayed its delivery until February 1991. The second gyrotron was able to operate for 1 s at 500 kW and 2 s at 300 kW, but failed when the cavity suffered thermal damage

  17. Carbon black directed synthesis of ultrahigh mesoporous carbon aerogels

    Macías, Carlos; Haro Remón, Marta; Rasines, Gloria; Parra Soto, José Bernardo; Ovín Ania, María Concepción

    2013-01-01

    [EN] A simple modification of the conventional sol–gel polymerization of resorcinol–formaldehyde mixtures allowed a facile preparation of ultrahigh mesoporous carbon gels. In the conventional synthesis the growth of the cluster polymer particles leading to the development of the porosity is controlled by the R/C ratio. In the presence of a carbon conductive additive, the polymerization of the reactants proceeded through the formation of less-branched polymer clusters resulting in carbon gels ...

  18. Direct carbon dioxide emissions from civil aircraft

    Grote, Matt; Williams, Ian; Preston, John

    2014-10-01

    Global airlines consume over 5 million barrels of oil per day, and the resulting carbon dioxide (CO2) emitted by aircraft engines is of concern. This article provides a contemporary review of the literature associated with the measures available to the civil aviation industry for mitigating CO2 emissions from aircraft. The measures are addressed under two categories - policy and legal-related measures, and technological and operational measures. Results of the review are used to develop several insights into the challenges faced. The analysis shows that forecasts for strong growth in air-traffic will result in civil aviation becoming an increasingly significant contributor to anthropogenic CO2 emissions. Some mitigation-measures can be left to market-forces as the key-driver for implementation because they directly reduce airlines' fuel consumption, and their impact on reducing fuel-costs will be welcomed by the industry. Other mitigation-measures cannot be left to market-forces. Speed of implementation and stringency of these measures will not be satisfactorily resolved unattended, and the current global regulatory-framework does not provide the necessary strength of stewardship. A global regulator with ‘teeth' needs to be established, but investing such a body with the appropriate level of authority requires securing an international agreement which history would suggest is going to be very difficult. If all mitigation-measures are successfully implemented, it is still likely that traffic growth-rates will continue to out-pace emissions reduction-rates. Therefore, to achieve an overall reduction in CO2 emissions, behaviour change will be necessary to reduce demand for air-travel. However, reducing demand will be strongly resisted by all stakeholders in the industry; and the ticket price-increases necessary to induce the required reduction in traffic growth-rates place a monetary-value on CO2 emissions of approximately 7-100 times greater than other common

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

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

    2015-01-01

    Hybrid direct carbon fuel cells (HDCFCs) consisting of a solid carbon (carbon black)-molten carbonate ((62–38 wt% Li-K)2CO3) mixtures in the anode chamber of an anode-supported solid oxide fuel cell type full-cell are tested for their electrochemical performance between 700 and 800°C. Performance...

  20. A new direction in search of "missing" carbon sinks

    2008-01-01

    @@ A CAS scientist succeeds in developing a new direction for exploring the inorganic carbon cycle of the earth. His creative work was recently reported by the 20th issue of Chinese Science Bulletin in 2007.

  1. Direct pressure sensor using carbon nanotubes nanocomposite

    Dinh, Nghia Trong

    2016-01-01

    Im Gegensatz zu herkömmlichen Dehnungsmessstreifen können Carbon nanotube (CNT)-basierte Komposite zusätzlich eine ausgeprägte Druck-abhängigkeit des Widerstandes aufweisen. Deshalb können Drucksensoren aus CNT-Nanokomposite ohne den Einsatz von Verformungskörpern wie z. B. Biegebalken aufgebaut werden. Die möglichen Anwendungsgebiete für diese direkt messenden Sensoren wurden in der vorliegenden Arbeit bei drei industriellen Anwendungen wie z. B. bei Robotergreifarmen gezeigt. Die Zielstellu...

  2. 1.2-MW CW high-power klystron for accelerator

    A super power CW klystron was developed for TRISTAN accelerator at National Laboratory of High Energy Physics, Japan. The klystron can deliver 1.2 MW at 508.6 MHz with an efficiency of 62 % and a gain of 54 DB. The collector is vapor-cooled and the output window is a 152D coaxial disk type. A TiN coating on the output window is a key technique to suppress multipactoring discharge of the window. (author)

  3. Direct carbon emissions from Canadian forest fires, 1959-1999

    Fire is recognised as driving most of the boreal forest carbon balance in North America, therefore fires not only impact on carbon sequestration by forests, but emit greenhouse gases that have the potential to affect the environment. In this paper direct emissions of carbon from Canadian forest fires were estimated for all of Canada and for each ecozone for the period 1959 to 1999. Estimates were based on large fires ; fuel consumption for each fire was calculated using the Canadian Forest Fire Behaviour Prediction System. There were about 11,400 forest fires, averaging 2 x 106 hectare per year during this period. Boreal and taiga areas experienced the greatest area burned, releasing most of the carbon. The mean area-weighted fuel consumption for all fires was 2.6 kg of dry fuel per m2 (1.3 kg carbon per m2) varying from 1.8 kg to 3.9 kg per m2 among ecozones. The mean annual direct carbon emission was estimated at 27 + or - 6 Tg carbon per year, or about 18 per cent of current carbon dioxide emissions from the Canadian energy sector, on average. This excludes post-fire effects, which cause an additional loss of carbon; changes to the forest also affect the strength of the forest carbon sink. Fire emissions have shown an increase over the past two decades and are likely to remain high due to anticipated changes in fire weather resulting from climate warming. 48 refs., 3 tabs., 6 figs

  4. Carbon Nanotubes Potentialities in Directional Dark Matter Searches

    Capparelli, L M; Mazzilli, D; Polosa, A D

    2014-01-01

    We propose a new solution to the problem of dark matter directional detection based on large parallel arrays of carbon nanotubes. The phenomenon of ion channeling in single wall nanotubes is simulated to calculate the expected number of recoiling carbon ions, due to the hypothetical scattering with dark matter particles, subsequently being driven along their longitudinal extension. As shown by explicit calculation, the relative orientation of the carbon nanotube array with respect to the direction of motion of the Sun has an appreciable effect on the channeling probability of the struck ion and this provides the required detector anisotropic response.

  5. Direct Use of Mineral Carbonate for Autotrophy Among Euendolithic Cyanobacteria

    Guida, B. S.

    2015-12-01

    Cyanobacteria are oxygenic photoautotrophs, and arguably the most important primary producers on the planet, fixing carbon from dissolved inorganic carbon (DIC) in the aquatic environment, and directly from atmospheric CO2 in terrestrial systems. Euendolithic cyanobacteria occupy a very specific niche, inside rocks, which can potentially preclude them from easily accessing those carbon pools, and yet, natural euendolithic communities can support food webs in habitats where they are prominent, such as in marine carbonate platforms and desert carbonate outcrops. In a recently proposed model describing the mechanism of cyanobacterial carbonate boring, we postulated that as the organism dissolves the mineral, liberated CO32- anions will be quickly converted to HCO3- and assimilated directly, making the cyanobacterium independent of external DIC pools for autotrophy. We used natural abundance and tracer stable carbon (13C) isotope analyses accompanied by nanoSIMS imaging in model laboratory systems of cultivated cyanobacteria and in natural mixed communities of marine euendoliths to study the ultimate source of carbon in their biomass. Our results clearly demonstrate that endolithic biomass of these cyanobacteria is significantly derived from mineral carbonate, as opposed to free-living or epilithic biomass, where the source is mixed or coming from the dissolved pool, this holds for model cultures as well as natural communities. In fact, we can increase the lifestyle preference of cultures for endolithic growth versus planktonic or benthic growth, by simply imposing an external DIC limitation in the presence of a carbonate substrate. Our results predict that benthic communities (extant or fossil) that rely heavily on primary production by euendolithic primary producers may show 13C signatures that mimic those of the surrounding carbonate substrate rather than from those of the local seawater.

  6. Directional couplers with integrated carbon nanotube incandescent light emitters

    Fechner, Randy G.; Pyatkov, Felix; Khasminskaya, Svetlana; Flavel, Benjamin S.; Krupke, Ralph; Pernice, Wolfram H. P.

    2016-01-01

    We combine on-chip single-walled carbon nanotubes (SWNTs) emitters with directional coupling devices as fundamental building blocks for carbon photonic systems. These devices are essential for studying the emission properties of SWNTs in the few photon regime for future applications in on-chip quantum photonics. The combination of SWNTs with on-chip beam splitters herein provides the basis for correlation measurements as necessary for nanoscale source characterization. The employed fabricatio...

  7. Direct integration of carbon nanotubes in Si microstructures

    In this paper we present a low-cost, room-temperature process for integrating carbon nanotubes on Si microsystems. The process uses localized resistive heating by controlling current through suspended microbridges, to provide local temperatures high enough for CVD growth of carbon nanotubes. Locally grown carbon nanotubes make electrical connections through guidance by electric fields, thus eventually making circuits. The process is scalable to a wafer level batch process. Furthermore, it is controlled electrically, thus enabling automated control. Direct integration of carbon nanotubes in microstructures has great promise for nano-functional devices, such as ultrasensitive chemical sensors. Initial measurements demonstrate the Si–carbon nanotube–Si circuit's potential as a NH3 sensor. (paper)

  8. A 2 MW, 170 GHz coaxial cavity gyrotron - experimental verification of the design of main components

    A 2 MW, CW, 170 GHz coaxial cavity gyrotron is under development in cooperation between European Research Institutions (FZK Karlsruhe, CRPP Lausanne, HUT Helsinki) and the European tube industry (TED, Velizy, France). The design of critical components has recently been examined experimentally at FZK Karlsruhe with a short pulse (∼ few ms) coaxial cavity gyrotron. This gyrotron uses the same cavity and the same quasioptical (q.o.) RF-output system as designed for the industrial prototype and a very similar electron gun

  9. 2 MW Active Bouncer Converter Design for Long Pulse Klystron Modulators

    Aguglia, D

    2012-01-01

    This paper presents some design issues of a 2 MW interleaved buck converter which is used as an active bouncer droop compensator for a 5.5MW long pulse klystron modulator. This novel design concept presents many challenges in terms of voltage ripple versus pulse rise-time. Issues related to the voltage ripple specification versus output filter design are discussed in detail. The design study is analyzed analytically, simulated numerically and is validated by experimental results obtained from a full power prototype.

  10. Development of a 2 MW CW Waterload for Electron Cyclotron Heating Systems

    R. Lawrence,Ives; Maxwell Mizuhara; George Collins; Jeffrey Neilson; Philipp Borchard

    2012-11-09

    Calabazas Creek Research, Inc. developed a load capable of continuously dissipating 2 MW of RF power from gyrotrons. The input uses HE11 corrugated waveguide and a rotating launcher to uniformly disperse the power over the lossy surfaces in the load. This builds on experience with a previous load designed to dissipate 1 MW of continuous RF power. The 2 MW load uses more advanced RF dispersion to double the capability in the same size device as the 1 MW load. The new load reduces reflected power from the load to significantly less than 1 %. This eliminates requirements for a preload to capture reflected power. The program updated control electronics that provides all required interlocks for operation and measurement of peak and average power. The program developed two version of the load. The initial version used primarily anodized aluminum to reduce weight and cost. The second version used copper and stainless steel to meet specifications for the ITER reactor currently under construction in France. Tests of the new load at the Japanese Atomic Energy Agency confirmed operation of the load to a power level of 1 MW, which is the highest power currently available for testing the load. Additional tests will be performed at General Atomics in spring 2013. The U.S. ITER organization will test the copper/stainless steel version of the load in December 2012 or early in 2013. Both loads are currently being marketed worldwide.

  11. Porous carbon as electrode material in direct ethanol fuel cells (DEFCs) synthesized by the direct carbonization of MOF-5

    Khan, Inayatali

    2014-01-12

    Porous carbon (PC-900) was prepared by direct carbonization of porous metal-organic framework (MOF)-5 (Zn4O(bdc)3, bdc=1,4-benzenedicarboxylate) at 900 °C. The carbon material was deposited with PtM (M=Fe, Ni, Co, and Cu (20 %) metal loading) nanoparticles using the polyol reduction method, and catalysts PtM/PC-900 were designed for direct ethanol fuel cells (DEFCs). However, herein, we are reporting PtFe/PC-900 catalyst combination which has exhibited superior performance among other options. This catalyst was characterized by powder XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) technique. The electrocatalytic capability of the catalyst for ethanol electrooxidation was investigated using cyclic voltammetry and direct ethanol single cell testing. The results were compared with those of PtFe and Pt supported on Vulcan XC72 carbon catalysts (PFe/CX-72 and Pt/XC-72) prepared via the same method. It has been observed that the catalyst PtFe/PC-900 developed in this work showed an outstanding normalized activity per gram of Pt (6.8 mA/g Pt) and superior power density (121 mW/cm2 at 90 °C) compared to commercially available carbon-supported catalysts. © Springer-Verlag Berlin Heidelberg 2014.

  12. Direct growth of carbon nanotubes on hydroxyapatite using MPECVD

    Graphical abstract: Carbon nanotubes have been grown directly on hydroxyapatite by using microwave plasma-enhanced chemical vapor deposition (MPECVD). Highlights: ► CNTs have been successfully grown directly on hydroxyapatite using MPECVD. ► Diameter distribution of the CNTs lies in the range from 30 to 70 nm. ► The HA surface is partially transformed to β-TCP during the deposition. ► Grown CNTs have good quality and IG/ID ratio lies between 1.243 and 1.774. - Abstract: For the first time carbon nanotubes (CNTs) have been successfully grown directly on hydroxyapatite (HA) by using microwave plasma enhanced chemical vapor deposition (MPECVD). Such integration has potential to capitalize on the merits of both HA and CNTs. This type of coating could be useful to improve the interface between bone and the implant. Scanning electron microscope SEM investigations show that; the surface of the CNTs is relatively clean and free of amorphous carbon. The CNTs diameters lie in the range 30–70 nm. In addition HA encapsulation by carbon was observed at a growth temperature 750 °C. Raman spectroscopy indicates that the CNTs are of high quality and the IG/ID ratio lies between 1.243 and 1.774. The changes in the X-ray diffraction (XRD) patterns give an indication that during the plasma deposition the HA-substrate surface is subjected to a temperature sufficient for partial conversion to the β-tricalcium phosphate via dehydroxylation.

  13. Tank Design Evaluation Of TRIGA Mark II Reactor For 2 MW Power

    . Design calculation, safety factor choosing, and welding procedure on tank design of Bandung nuclear reactor for 2 MW power have been evaluated. For design calculation, the evaluation has especially done based on material strength input which was used on tank thickness calculation. Evaluation on safety factor choosing has been done by comparing the result of final calculation after inputting the value of safety factor to the physics condition will be occurred. On welding procedure, the evaluation has been carried to see the chance will be occurred if the excising design followed. From this evaluation, it can be concluded that the calculation just done to meet the result of the calculation to the thickness of material has been excised so it can be assumed as proper material of tank reactor

  14. Physical influence of spherical packing rate on the 2 MW AHTR

    Background: With a constant fuel inventory, the pebble packing rate has an important influence on the physical property of AHTR. Purpose: This paper attempts to study the influence of the pebble packing on a 2 MW AHTR. Methods: We used Monte Carlo Code MCNP 5 to study the related parameters, such as Keff, neutron spectrum and neutron flux distribution. In the analysis, we changed the packing from 0.7405 to 0.5236. Results: Results show that the changes of the pebble packing could increase the Keff of the core, make the neutron spectrum harder, and make the neutron flux peak up in axial position. Conclusions: Results provide rational theory for the design of AHTR and the development of computation code. (authors)

  15. Status of the 2 MW, 170 GHz coaxial cavity gyrotron for ITER

    Full text: A 170 GHz coaxial cavity gyrotron with 2 MW output power in continuous wave (CW) operation is under development in cooperation between European research centres together with European industry. A first industrial prototype of such a gyrotron has already been fabricated and delivered to CRPP Lausanne, where a suitable test facility has been constructed. Due to a delay in fabrication the delivery of the gyrotron magnet is expected in May 2007. Thus experimental tests are expected for the second half of this year. In parallel to the industrial activities, experimental operation with a short pulse (∼ few ms) 170 GHz coaxial gyrotron ('pre-prototype') which uses the same main components as designed for the industrial tube has been continued. The mechanism of parasitic low frequency (LF) oscillations around 260 MHz has been identified. Based on this identification, small modifications of the geometry of the coaxial insert have been made. As a result the starting current for the LF oscillations has been increased by a factor of about 3 causing a strong reduction of the LF amplitude. Measurements with a prototype of a microwave load, which has been designed and fabricated for operation with the 2 MW prototype tube, have been performed. In addition to the distribution of the microwave power absorbed on the wall, the amount of power reflected back into the gyrotron has been measured and its influence on gyrotron performance has been investigated. The performance of the quasi optical (q.o.) RF output system presently installed in the industrial prototype tube is insufficient, mainly because of the low Gaussian content of the RF output beam. As a first step a new launcher with a different wall corrugation and a new adapted phase correcting mirror has been designed and fabricated. According to simulations an increase of the Gaussian content to about 87% is expected. This q.o. RF output system has been installed in the pre-prototype tube for performing hot

  16. Performance evaluation of a tubular direct carbon fuel cell operating in a packed bed of carbon

    The DCFC (direct carbon fuel cell) technology, based on the direct electrochemical oxidation of carbon, has the potential to double the electric efficiency and half the CO2 emissions compared to conventional coal fired power plants. In order to assess the scalability of the technology in terms of fabrication and fuel feed system, and to elucidate the possible causes of the cell degradation, a tubular DCFC has been fabricated and operated in a pulverised carbon packed bed at around 800 °C. The cell was operated for a total period of 11 days with many thermal cycles. The electrochemical impedance spectroscopy was used to elucidate the possible causes of the cell degradation. Post-mortem analysis of the cell with SEM (scanning electron microscopy) and XRD (X-ray diffraction) confirmed structural stability of both air and fuel electrodes. A peak power density of 30 mW cm−2 was obtained by direct contact of carbon to the fuel electrode with high purity He as the purge gas. The cell, at the end of operation was still found to produce 60% of the power relative to the power at the beginning of operation, and this study demonstrates the feasibility of continuous operation of the tubular fuel cell in a packed bed of carbon. - Highlights: • A direct carbon fuel cell was operated for 11 days in a packed carbon bed. • Scalability and continuous operation of fuel cell on solid carbon demonstrated. • MIEC (Mixed ion electronic conducting) anode (LSCF) showed reasonable stability. • Major degradation source is lack of carbon contact with anode as it is consumed

  17. Direct measurement of riverine particulate organic carbon age structure

    Rosenheim, Brad E.; Galy, Valier

    2012-10-01

    Carbon cycling studies focusing on transport and transformation of terrigenous carbon sources toward marine sedimentary sinks necessitate separation of particulate organic carbon (OC) derived from many different sources and integrated by river systems. Much progress has been made on isolating and characterizing young biologically-formed OC that is still chemically intact, however quantification and characterization of old, refractory rock-bound OC has remained troublesome. Quantification of both endmembers of riverine OC is important to constrain exchanges linking biologic and geologic carbon cycles and regulating atmospheric CO2 and O2. Here, we constrain petrogenic OC proportions in suspended sediment from the headwaters of the Ganges River in Nepal through direct measurement using ramped pyrolysis radiocarbon analysis. The unique results apportion the biospheric and petrogenic fractions of bulk particulate OC and characterize biospheric OC residence time. Compared to the same treatment of POC from the lower Mississippi-Atchafalaya River system, contrast in age spectra of the Ganges tributary samples illustrates the difference between small mountainous river systems and large integrative ones in terms of the global carbon cycle.

  18. Nanowelding configuration between carbon nanotubes in axial direction

    Highlights: ► Nanowelding process could be accomplished at a lower temperature than the melting point of the bulk solder. ► CNTs are connected with solder joints of nodule shape. ► Some silver atoms are captured and dragged into carbon nanotube to form the core filling structures of nanowires. ► Some silver atoms diffuse along the outer walls of SWNTs with the dominant mechanism of capillary wetting. - Abstract: Interconnect technology of carbon nanotubes (CNTs) is essential for functional devices. However, difficulty in the fabrication of the interface between carbon nanotube (CNT) and CNT in axial direction, hindered the quality of connection and practical applications of electrical devices. Also, investigation of dynamic evolution of connection configuration about nanowelding is still lacking. In order to analyze the nanowelding configuration between CNTs in axial direction, the different connection cases are investigated using molecular dynamics simulation. Simulation results show that the nanowelding process could be accomplished at a lower temperature than the melting point of the bulk solder and the CNTs are connected with solder joints of nodule shape. It is also found that metal atoms are captured and dragged into nanotube to form the core filling structures of nanowires during nanowelding. Also, the connection configuration shows that Ag atoms diffuse along the outer walls of SWNTs with the dominant mechanism of capillary wetting, which would increase the contact length to improve the mechanical strength.

  19. Estimation of Direct Carbon Emissions from Chinese Forest Fires

    TIANXiaorui; GAOChengde; SHULifu; WANGMingyu; YANGXiaohui

    2004-01-01

    Many studies indicated that the products of biosphere burning have short and long-term effects on the atmosphere. Vegetation burning can produce some gases which have significant influence on environment, including some greenhouse gases as CO2 and CH4, etc. Smoke aerosols produced from burning also influence global climate and atmospheric chemistry. The paper calculates the consumed biomass due to forest fires according to the statistics of forest fires from 1991 to 2000 and research results of biomass of Chinese forests. During the study period, forest fires burned average 5Tg-7Tg biomass each year and directly emitted 20.24 Tg-28.56 Tg carbon. In 1991-2000, average emission of carbon dioxide and CH4 account for 2.7%-3.9% and 3.3%-4.7% of the total emission of China (calculating with the data of 2000), respectively.

  20. Carbon-Carbon Composites as Recuperator Materials for Direct Gas Brayton Systems

    Of the numerous energy conversion options available for a space nuclear power plant (SNPP), one that shows promise in attaining reliable operation and high efficiency is the direct gas Brayton (GB) system. In order to increase efficiency, the GB system incorporates a recuperator that accounts for nearly half the weight of the energy conversion system (ECS). Therefore, development of a recuperator that is lighter and provides better performance than current heat exchangers could prove to be advantageous. The feasibility of a carbon-carbon (C/C) composite recuperator core has been assessed and a mass savings of 60% and volume penalty of 20% were projected. The excellent thermal properties, high-temperature capabilities, and low density of carbon-carbon materials make them attractive in the GB system, but development issues such as material compatibility with other structural materials in the system, such as refractory metals and superalloys, permeability, corrosion, joining, and fabrication must be addressed

  1. Carbon-Carbon Composites as Recuperator Material for Direct Gas Brayton Systems

    RA Wolf

    2006-07-19

    Of the numerous energy conversion options available for a space nuclear power plant (SNPP), one that shows promise in attaining reliable operation and high efficiency is the direct gas Brayton (GB) system. In order to increase efficiency, the GB system incorporates a recuperator that accounts for nearly half the weight of the energy conversion system (ECS). Therefore, development of a recuperator that is lighter and provides better performance than current heat exchangers could prove to be advantageous. The feasibility of a carbon-carbon (C/C) composite recuperator core has been assessed and a mass savings of 60% and volume penalty of 20% were projected. The excellent thermal properties, high-temperature capabilities, and low density of carbon-carbon materials make them attractive in the GB system, but development issues such as material compatibility with other structural materials in the system, such as refractory metals and superalloys, permeability, corrosion, joining, and fabrication must be addressed.

  2. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  3. The thermodynamics of direct air capture of carbon dioxide

    implementation of air capture but leaves quite some leeway for unavoidable inefficiencies in practical systems. - Highlights: ► The thermodynamics of capturing carbon dioxide from ambient air is analyzed. ► The free energy of mixing is analyzed for reversible and irreversible absorption processes. ► Thermal and moisture swing methods of capturing carbon dioxide are analyzed. ► Efficiencies of a single sorbent system and an attainable efficiency for air capture are identified. ► Thermodynamics are shown to not pose stringent constraints on direct air capture

  4. Experimental determination and modeling of the phase behavior for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide

    Tsivintzelis, Ioannis; Musko, Nikolai E.; Baiker, Alfons;

    2013-01-01

    This study focuses on the investigation of the phase behavior of mixtures relevant to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The bubble points of corresponding quaternary mixtures of varying composition were experimentally determined. The Cubic...

  5. Direct Oil Recovery from Saturated Carbon Nanotube Sponges.

    Li, Xiying; Xue, Yahui; Zou, Mingchu; Zhang, Dongxiao; Cao, Anyuan; Duan, Huiling

    2016-05-18

    Oil adsorption by porous materials is a major strategy for water purification and industrial spill cleanup; it is of great interest if the adsorbed oil can be safely recovered from those porous media. Here, direct oil recovery from fully saturated bulk carbon nanotube (CNT) sponges by displacing oil with water in controlled manner is shown. Surfactant-assisted electrocapillary imbibition is adopted to drive aqueous electrolyte into the sponge and extrude organic oil out continuously at low potentials (up to -1.2 V). More than 95 wt % of oil adsorbed within the sponge can be recovered, via a single electrocapillary process. Recovery of different oils with a wide range of viscosities is demonstrated, and the remaining CNT sponge can be reused with similar recovery capacity. A direct and efficient method is provided to recover oil from CNT sponges by water imbibition, which has many potential environmental and energy applications. PMID:27120687

  6. Revisiting direct electron transfer in nanostructured carbon laccase oxygen cathodes.

    Adam, Catherine; Scodeller, Pablo; Grattieri, Matteo; Villalba, Matías; Calvo, Ernesto J

    2016-06-01

    The biocatalytic electroreduction of oxygen has been studied on large surface area graphite and Vulcan® carbon electrodes with adsorbed Trametes trogii laccase. The electrokinetics of the O2 reduction reaction (ORR) was studied at different electrode potentials, O2 partial pressures and concentrations of hydrogen peroxide. Even though the overpotential at 0.25 mA·cm(-2) for the ORR at T1Cu of the adsorbed laccase on carbon is 0.8 V lower than for Pt of similar geometric area, the rate of the reaction and thus the operative current density is limited by the enzyme reaction rate at the T2/T3 cluster site for the adsorbed enzyme. The transition potential for the rate determining step from the direct electron transfer (DET) to the enzyme reaction shifts to higher potentials at higher oxygen partial pressure. Hydrogen peroxide produced by the ORR on bare carbon support participates in an inhibition mechanism, with uncompetitive predominance at high H2O2 concentration, non-competitive contribution can be detected at low inhibitor concentration. PMID:26883057

  7. Development of tubular hybrid direct carbon fuel cell and pyrolysis of biomass for production of carbon fuel

    Bonaccorso, Alfredo Damiano

    2013-01-01

    This study involved two avenues of investigation: a new concept of Direct Carbon Fuel Cell (DCFC) and the production of carbon from biomass. The new concept of DCFC merges a solid oxide electrolyte and a molten carbonate electrolyte called the “hybrid direct carbon fuel cell” using tubular geometry. The tubular cell was chosen for several reasons, such as sealing process, reduction of stress during the sintering process and reduction of the final size of the stack. In addition, it makes th...

  8. Promoting direct interspecies electron transfer with activated carbon

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

    2012-01-01

    Granular activated carbon (GAC) is added to methanogenic digesters to enhance conversion of wastes to methane, but the mechanism(s) for GAC’s stimulatory effect are poorly understood. GAC has high electrical conductivity and thus it was hypothesized that one mechanism for GAC stimulation of...... methanogenesis might be to facilitate direct interspecies electron transfer (DIET) between bacteria and methanogens. Metabolism was substantially accelerated when GAC was added to co-cultures of Geobacter metallireducens and Geobacter sulfurreducens grown under conditions previously shown to require DIET. Cells...... were attached to GAC, but did not aggregate as they do when making biological electrical connections between cells. Studies with a series of gene deletion mutants eliminated the possibility that GAC promoted electron exchange via interspecies hydrogen or formate transfer and demonstrated that DIET in...

  9. Carbon Dioxide Direct Cycle Modular Reactors for Decentralized Energy Sources

    Carbon dioxide is achievable higher cycle efficiency than helium in a direct gas turbine cycle system due to the real gas effect or inter molecular attraction force in the compression process especially in the vicinity of the critical points. Analyzing the cycle thermal performance of full, partial and non condensation cycles, the cycle efficiency is highest in the partial condensation cycle. A fast reactor employing the partial condensation cycle is expected to be a potential alternative option to LMFRs, allowing higher cycle efficiency than LMFRs at the same core outlet temperature, and excluding the problems related to safety, cost and maintenance. A thermal reactor employing the partial condensation cycle provides higher cycle efficiency (48%) at the moderate core outlet temperature of 650? than that of PBMR (46%) operated at 900? (author)

  10. Direct Carbon Fuel Cell System Utilizing Solid Carbonaceous Fuels

    Turgut Gur

    2010-04-30

    This 1-year project has achieved most of its objective and successfully demonstrated the viability of the fluidized bed direct carbon fuel cell (FB-DCFC) approach under development by Direct Carbon technologies, LLC, that utilizes solid carbonaceous fuels for power generation. This unique electrochemical technology offers high conversion efficiencies, produces proportionately less CO{sub 2} in capture-ready form, and does not consume or require water for gasification. FB-DCFC employs a specialized solid oxide fuel cell (SOFC) arrangement coupled to a Boudouard gasifier where the solid fuel particles are fluidized and reacted by the anode recycle gas CO{sub 2}. The resulting CO is electrochemically oxidized at the anode. Anode supported SOFC structures employed a porous Ni cermet anode layer, a dense yttria stabilized zirconia membrane, and a mixed conducting porous perovskite cathode film. Several kinds of untreated solid fuels (carbon and coal) were tested in bench scale FBDCFC prototypes for electrochemical performance and stability testing. Single cells of tubular geometry with active areas up to 24 cm{sup 2} were fabricated. The cells achieved high power densities up to 450 mW/cm{sup 2} at 850 C using a low sulfur Alaska coal char. This represents the highest power density reported in the open literature for coal based DCFC. Similarly, power densities up to 175 mW/cm{sup 2} at 850 C were demonstrated with carbon. Electrical conversion efficiencies for coal char were experimentally determined to be 48%. Long-term stability of cell performance was measured under galvanostatic conditions for 375 hours in CO with no degradation whatsoever, indicating that carbon deposition (or coking) does not pose any problems. Similar cell stability results were obtained in coal char tested for 24 hours under galvanostatic conditions with no sign of sulfur poisoning. Moreover, a 50-cell planar stack targeted for 1 kW output was fabricated and tested in 95% CO (balance CO{sub 2

  11. 2.2 MW Operation of the European Coaxial-Cavity Pre-Prototype Gyrotron for ITER

    Full text: A 2 MW, CW, 170 GHz coaxial-cavity gyrotron for electron cyclotron heating and current drive in the International Thermonuclear Experimental Reactor (ITER) is under development within an European Gyrotron Consortium (EGYC*). To support the development of the industrial prototype of a CW gyrotron, a short pulse tube (pre-prototype) is used at KIT (former FZK) for experimental verification of the design of critical components, such as electron gun, beam tunnel, cavity and quasi-optical (q.o.) RF-output coupler. Significant progress was achieved recently. In particular, RF output power of up to 2.2 MW with 30% output efficiency has been obtained in single-mode operation at 170 GHz. Furthermore, an excellent quality of the RF output beam with ∼ 96% fundamental Gaussian mode content has been obtained by using a new quasi-optical RF output system. The verification of these results with computer simulations will be presented. (author)

  12. The Neutronic And Power Distribution Calculations For Triga 2 MW Reactor Using WIMS-D/4 And Citation Codes

    . The neutronic calculation has been carried out for TRIGA 2 MW reactor. These included criticality flux and power distributions. Computer code Citation which solves 7-groups, 3-dimensional hexagonal geometry has been used. The multi groups-cross-section is generated by the WIMS-D/4 code.This 7-group-39x39x38-mesh-points problem takes about 90 minutes on the Pentium-133 MHz PC. The calculation of the initial core of TRIGA 2 MW reactor shows that the excess reactivity of the core is 7,8% and the thermal fluxes in the irradiation positions are between 1.0-2.9*1013n cm-2s-1. The results are about 10% deviate from those calculated by General Atomics. In the initial core, the highest power is produced in the C-9 position. The fuel element in this position produces 30.7 k W thermal power

  13. Collector Failures on 350 MHz, 1.2 MW CW Klystrons at the Low Energy Demonstration Accelerator (LEDA)

    Rees, D.; Roybal, W.; Bradley, J.

    2000-01-01

    We are currently operating the front end of the accelerator production of tritium (APT) accelerator, a 7 MeV radio frequency quadrapole (RFQ) using three, 1.2 MW CW klystrons. These klystrons are required and designed to dissipate the full beam power in the collector. The klystrons have less than 1500 operational hours. One collector has failed and all collectors are damaged. This paper will discuss the damage and the difficulties in diagnosing the cause. The collector did not critically fail...

  14. Achieving high performance in intermediate temperature direct carbon fuel cells with renewable carbon as a fuel source

    Highlights: • Bamboo fiber and waste paper were pyrolyzed to generate bamboo carbon and waste paper carbon as anode fuels of IT-DCFC. • Superior cell performance was achieved with the waste paper carbon. • The results suggested the high performance was due to the highest thermal reactivity and the catalytic inherent impurities. • Calcite and kaolinite as inherent impurities favored the thermal decomposition and the electrooxidation of carbon. - Abstract: Three kinds of carbon sources obtained from carbon black, bamboo fiber and waste paper were investigated as anode fuels in an intermediate temperature direct carbon fuel cell. The carbon sources were characterized with X-ray photoelectron spectroscopy, thermal gravimetric analysis, etc. The results indicated that the waste paper carbon was more abundant in calcite and kaolinite, and showed higher thermal reactivity in the intermediate temperature range compared with the other two carbon sources. The cell performance was tested at 650 °C in a hybrid single cell, using Sm0.20Ce0.80O2−x as the electrolyte. As a result, the cell fed with waste paper carbon showed the highest performance among the three carbon sources, with a peak power density of 225 mW cm−2. The results indicated that its inherent impurities, such as calcite and kaolinite, might favor the thermal gasification of renewable carbon sources, which resulted in the enhanced performance of the intermediate temperature direct carbon fuel cell

  15. Direct membrane-carbonation photobioreactor producing photoautotrophic biomass via carbon dioxide transfer and nutrient removal.

    Kim, Hyun-Woo; Cheng, Jing; Rittmann, Bruce E

    2016-03-01

    An advanced-material photobioreactor, the direct membrane-carbonation photobioreactor (DMCPBR), was tested to investigate the impact of directly submerging a membrane carbonation (MC) module of hollow-fiber membranes inside the photobioreactor. Results demonstrate that the DMCPBR utilized over 90% of the supplied CO2 by matching the CO2 flux to the C demand of photoautotrophic biomass growth. The surface area of the submerged MC module was the key to control CO2 delivery and biomass productivity. Tracking the fate of supplied CO2 explained how the DMCPBR reduced loss of gaseous CO2 while matching the inorganic carbon (IC) demand to its supply. Accurate fate analysis required that the biomass-associated C include soluble microbial products as a sink for captured CO2. With the CO2 supply matched to the photosynthetic demand, light attenuation limited the rate microalgal photosynthesis. The DMCPBR presents an opportunity to improve CO2-deliver efficiency and make microalgae a more effective strategy for C-neutral resource recovery. PMID:26771923

  16. Performance analysis of a direct carbon fuel cell with molten carbonate electrolyte

    The model of a packed bed anode DCFC (direct carbon fuel cell) with molten carbonate as an electrolyte and graphite as a fuel is established to globally evaluate its performance. Thermodynamic-electrochemical analyses on the performance of the DCFC are implemented, in which the activation overpotential, ohmic overpotential, and concentration overpotential are taken as the main sources of voltage losses. The analytical expressions for the cell voltage, power output, efficiency, and entropy production rate are derived, from which the general performance characteristics are discussed in detail. At the anode, the ohmic overpotential in each slab resulting from the carbon phase is found to be about three orders of magnitude larger than that resulting from the electrolyte phase. The radius of the real contact area between two neighboring graphite particles decreases at an accelerating rate as one goes up in the bed, and the corresponding constriction resistance will increase at an accelerating rate. The decrease in the operating current density and anode dimension and the increase in the operating temperature will lessen the overall ohmic overpotential. The effects of the operating current density, operating temperature and anode dimension on the performance are discussed, and the optimum criteria for some important performance parameters are determined. - Highlights: • An irreversible model of a DCFC with molten carbonate electrolyte is proposed. • Main irreversible losses in the DCFC are analytically characterized. • General performance characteristics of the DCFC are revealed. • Optimum operation regions of some performance parameters are determined

  17. Development of a Direct Carbon Fuel Cell for Power and Fuels Cogeneration Directly from Plastic Trash Project

    National Aeronautics and Space Administration — This small business innovation research is intended to develop a simple processing concept based-on an advanced direct carbon fuel cell (DCFC) technology enabling...

  18. Progress and Future Directions in North American Carbon Cycle Science

    Michalak, Anna; Huntzinger, Deborah; Shrestha, Gyami

    2013-05-01

    The North American Carbon Program (NACP) convened its fourth biennial "All Investigators" meeting (AIM4, http://www.nacarbon.org/meeting_2013) to review progress in understanding the dynamics of the carbon cycle of North America and adjacent oceans and to chart a course for a more integrative and holistic approach to future research. The meeting was structured around the six decadal goals outlined in the new "A U.S. Carbon Cycle Science Plan" (Michalak et al., University Corporation for Atmospheric Research, 2011, available at http://www.carboncyclescience.gov) and focused on (1) diagnosis of the atmospheric carbon cycle, (2) drivers of anthropogenic emissions, (3) vulnerability of carbon stocks to change, (4) ecosystem impacts of change, (5) carbon management, and (6) decision support.

  19. Automated circuit fabrication and direct characterization of carbon nanotube vibrations.

    Zeevi, G; Shlafman, M; Tabachnik, T; Rogachevsky, Z; Rechnitz, S; Goldshtein, I; Shlafman, S; Gordon, N; Alchanati, G; Itzhak, M; Moshe, Y; Hajaj, E M; Nir, H; Milyutin, Y; Izraeli, T Y; Razin, A; Shtempluck, O; Kotchtakov, V; Yaish, Y E

    2016-01-01

    Since their discovery, carbon nanotubes have fascinated many researchers due to their unprecedented properties. However, a major drawback in utilizing carbon nanotubes for practical applications is the difficulty in positioning or growing them at specific locations. Here we present a simple, rapid, non-invasive and scalable technique that enables optical imaging of carbon nanotubes. The carbon nanotube scaffold serves as a seed for nucleation and growth of small size, optically visible nanocrystals. After imaging the molecules can be removed completely, leaving the surface intact, and thus the carbon nanotube electrical and mechanical properties are preserved. The successful and robust optical imaging allowed us to develop a dedicated image processing algorithm through which we are able to demonstrate a fully automated circuit design resulting in field effect transistors and inverters. Moreover, we demonstrate that this imaging method allows not only to locate carbon nanotubes but also, as in the case of suspended ones, to study their dynamic mechanical motion. PMID:27396506

  20. Diseño y construcción de un parque fotovoltaico de 2 MW en Albesa

    Rubio Solís, Oscar

    2007-01-01

    El presente proyecto tiene por objeto llevar a cabo el diseño y construcción de un parque fotovoltaico de 2 MW de potencia nominal en Albesa (Lleida), formado por 20 instalaciones fotovoltaicas independientes de 100 kW de potencia nominal, proporcionando una potencia fotovoltaica pico total de 2,261 MWp. La finalidad del parque fotovoltaico es generar el máximo de energía eléctrica con el objetivo de inyectarla a la red eléctrica y maximizar el beneficio económico por su venta,...

  1. Hybrid direct carbon fuel cells and their reaction mechanisms - a review

    Deleebeeck, Lisa; Kammer Hansen, Kent

    2014-01-01

    with carbon capture and storage (CCS) due to the high purity of CO2 emitted in the exhaust gas. Direct carbon (or coal) fuel cells (DCFCs) are directly fed with solid carbon to the anode chamber. The fuel cell converts the carbon at the anode and the oxygen at the cathode into electricity, heat and...... efforts is discussed on the fuel cell stack and system levels. The range of DCFC types can be roughly broken down into four fuel cell types: aqueous hydroxide, molten hydroxide, molten carbonate and solid oxide fuel cells. Emphasis is placed on the electrochemical reactions occurring at the anode and the...... proposed mechanism(s) of these reactions for molten carbonate, solid oxide and hybrid direct carbon fuel cells. Additionally, the criteria of choosing the ‘best’ DCFC technology is explored, including system design (continuous supply of solid fuel), performance (power density, efficiency), environmental...

  2. Direct Electrochemistry of Glucose Oxidase on Novel Free-Standing Nitrogen-Doped Carbon Nanospheres@Carbon Nanofibers Composite Film

    Xueping Zhang; Dong Liu; Libo Li; Tianyan You

    2015-01-01

    We have proposed a novel free-standing nitrogen-doped carbon nanospheres@carbon nanofibers (NCNSs@CNFs) composite film with high processability for the investigation of the direct electron transfer (DET) of glucose oxidase (GOx) and the DET-based glucose biosensing. The composites were simply prepared by controlled thermal treatment of electrospun polypyrrole nanospheres doped polyacrylonitrile nanofibers (PPyNSs@PAN NFs). Without any pretreatment, the as-prepared material can directly serve ...

  3. A new direction in search of "missing" carbon sinks

    2010-01-01

    @@ The sink-source imbalance in the global carbon cycle is a "hot spot" for scholars on the subject in the present-day world.So far,the CO2 sink's location,size,variation and the mechanism underlying its ever-changing trend are all controversial topics.Currently,the mainstream research in this aspect is concentrated mainly on the organic carbon's cycle while little,if not,attention is paid to the current status of the inorganic carbon sink.

  4. Hybrid Direct Carbon Fuel Cell Performance with Anode Current Collector Material

    Deleebeeck, Lisa; Kammer Hansen, Kent

    2015-01-01

    The influence of the current collector on the performance of a hybrid direct carbon fuel cell (HDCFC), consisting of solid oxide fuel cell (SOFC) with a molten carbonate-carbon slurry in contact with the anode, has been investigated using current-voltage curves. Four different anode current...... collectors were studied: Au, Ni, Ag, and Pt. It was shown that the performance of the direct carbon fuel cell (DCFC) is dependent on the current collector materials, Ni and Pt giving the best performance, due to their catalytic activity. Gold is suggested to be the best material as an inert current collector...

  5. The study of time-dependent neutronics parameters of the 2MW TRIGA Mark II Moroccan research reactor using BUCAL1 computer code

    The 2-MW TRIGA MARK II research reactor at Centre National de l'Energie, des Sciences et des Techniques Nucleaires (CNESTEN) achieved initial criticality on May 2, 2007 with 71 fuel elements. The reactor is designed to effectively implement the various fields of basic nuclear research, manpower and training and production of radioisotopes for their use in agriculture, industry and medicine. This work aims to study the time-dependent neutronics parameters of the TRIGA reactor for elaborating and planning of an in-core fuel management strategy to maximize the utilization of the TRIGA fluxes, using a new elaborated burnup computer code called 'BUCAL1'. The code can be used to aid in analysis, prediction, and optimization of fuel burnup performance in a nuclear reactor. It was developed to incorporate the neutron absorption tally/reaction information generated directly by MCNP5 code in the calculation of fissioned or neutron-transmuted isotopes for multi-fueled regions. The use of Monte Carlo method and punctual cross section data characterizing the MCNP code allows an accurate simulation of neutron life cycle in the reactor, and the integration of data on the entire energy spectrum, thus a more accurate estimation of results than deterministic code can do. Also, for the purpose of this study, a full-model of the TRIGA reactor was developed using the MCNP5 code. The validation of the MCNP model of the TRIGA reactor was made by benchmarking the reactivity experiments. (author)

  6. Direct synthesis of sp-bonded carbon chains on graphite surface by femtosecond laser irradiation

    Microscopic phase transformation from graphite to sp-bonded carbon chains (carbyne) and nanodiamond has been induced by femtosecond laser pulses on graphite surface. UV/surface enhanced Raman scattering spectra and x-ray photoelectron spectra displayed the local synthesis of carbyne in the melt zone while nanocrystalline diamond and trans-polyacetylene chains form in the edge area of gentle ablation. These results evidence possible direct 'writing' of variable chemical bonded carbons by femtosecond laser pulses for carbon-based applications

  7. Effect of CeO2 Infiltration on Hybrid Direct Carbon Fuel Cell Performance

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

    2014-01-01

    The effect of CeO2 infiltration into the anode or CeO2 mixed with the carbon-fuel on the performance of a Hybrid Direct Carbon Fuel Cell (HDCFC) was studied through the use of polarization curves and electrochemical impedance spectroscopy. The use CeO2 in both ways helped to increase the cell...

  8. Virginia Center for Coal and Energy Research directs project to test carbon capture sites

    Trulove, Susan

    2008-01-01

    The Virginia Center for Coal and Energy Research (VCCER) at Virginia Tech will direct the $2,399,736 Southeast Regional Carbon Sequestration Partnership (SECARB) Phase II Task 10 project to identify sites for a potential large-volume carbon dioxide (CO2) injection tests.

  9. Electrochemically oxidized carbon anode in direct L-ascorbic acid fuel cells

    The activity of electrochemically oxidized carbon electrode was investigated in the operation of a direct L-ascorbic acid fuel cell anode. The surface oxygen species placed on electrochemically oxidized carbon electrode were analyzed by X-ray photoelectron spectroscopy and cyclic voltammetry. The electrochemical oxidation process of carbon electrode can facilitate the pore-filling process (i.e., wetting) of the electrolyte into the microstructure of the carbon electrode by increasing the number of more polar functional groups on the electrode surface. The electrochemically oxidized carbon electrode exhibited significantly enhanced electro-catalytic oxidation activity of L-ascorbic acid compared to an unmodified carbon electrode. Moreover, the simplified electrode structure using carbon paper without an additional powder-based precious catalyst layer is very favorable in creating percolation network and generates power density of 18 mW/cm2 at 60 deg. C

  10. Direct Synthesis of Multicolor Fluorescent Hollow Carbon Spheres Encapsulating Enriched Carbon Dots

    Qiao-Ling Chen; Wen-Qing Ji; Su Chen

    2016-01-01

    Multicolor fluorescent hollow carbon spheres (HCSs) are fabricated by an easy one-step route of in situ pyrolysis process with the use of natural scales and collagen powders as the precursor. The gas blow forming mechanism and photoluminescence (PL) emission mechanism of HCSs have been thoroughly discussed and proved that HCSs represent the first examples of three-dimensional multicolor fluorescent nanomaterials based on carbon dots (CDs). The HCSs encapsulate enriched carbon dots with high q...

  11. Direct extraction of nuclear effects in quasielastic scattering on carbon

    Wilkinson, Callum

    2016-01-01

    The differences between neutrino and antineutrino CCQE cross sections measured on hydrocarbon targets are due to fundamental differences in the cross section, different neutrino and antineutrino fluxes from the same beamline, and the additional interactions on hydrogen for antineutrinos that are absent for neutrinos. In this analysis we correct for the former two differences to extract a constraint on the ratio of the CCQE cross section for free and bound protons from MINERvA and MiniBooNE data. This measures nuclear effects in carbon, and we compare this measurement to models.

  12. Promotion of the Direct Electron Transfer of Hemoglobin by the Carbon Nanotube

    Jing CHEN; Chen Xin CAI

    2004-01-01

    It is reported that the direct electron transfer of hemoglobin (Hb) can be effectively promoted by carbon nanotubes when Hb was immobilized on the surface of the carbon nanotubes modified electrode. The results indicated that the conversion of Hb-Fe(III)/Hb-Fe(II) is a one-electron coupled one-proton reaction process. The method presented can be easily extended to study the direct electrochemistry of other proteins or enzymes.

  13. Win-win strategies in directing low-carbon resilient development path

    This section explores big win-win strategies in directing low carbon resilient development path. There are lots of “leapfrog” development possibilities in developing countries, which go directly from a status of under-development through to efficient and environmentally benign lifestyle. To achieve low carbon resilient paths, not only technology development but also institutional and behavioral changes are required. Science-policy nexus is also discussed.

  14. Direct fabrication of Pt-supported porous carbon catalyst for fuel cell

    Zhang, D.Y.; Wang, G.; Konstantinov, K. [Wollongong Univ., NSW (Australia). Inst. for Superconducting and Electronic Materials; Ma, Z.F.; Liub, H.K. [Shanghai Jiaotong Univ., Shanghai (China). Dept. of Chemical Engineering

    2006-07-01

    Platinum (Pt) based electrocatalysts are generally used in proton exchange membrane fuel cells (PEMFC) and in direct alcohol fuel cells (DAFC) operating at relatively low temperature. Wet impregnation techniques and chemical reduction of the metal precursors are the conventional preparation methods for these electrocatalysts. These conventional synthesis methods are based on impregnation-reduction, microemulsions, sonochemistry, and microwave irradiation. However, Pt-supported carbon catalysts cannot be prepared by such methods due to the very long time needed for the synthesis of carbon. In addition, post-fabrication steps must be taken, such as surface modification of carbon and metal supporting. For these reasons, this study presented a new fabrication method for producing Pt-carbon catalysts directly by a Pt-embedded template. The new method provides a time saving route for the preparation of a Pt catalyst supported on a mesoporous carbon. In this study, Pt-supported porous carbon was prepared using the carbon xerogel method. In particular, a platinum salt was dissolved in an aqueous solution of carbon xerogel precursor and reduced under 5 per cent hydrogen/argon gas along with carbonization. Images from a scanning electron microscope revealed that the nanoscale particle structure of the Pt-embedded carbon electrocatalyst had homogeneously distributed bright particles, likely attributed to Pt. 10 refs.

  15. Enhancing hybrid direct carbon fuel cell anode performance using Ag2O

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

    2015-01-01

    A hybrid-direct carbon fuel cell (HDCFC), consisting of a molten slurry of solid carbon black and (Li-K)2CO3 added to the anode chamber of a solid oxide fuel cell, was characterized using current-potential-power density curves, electrochemical impedance spectroscopy, and cyclic voltammetry. Two...... temperature (700-800 °C) and anode sweep gas (N2, 4-100% CO2 in N2-CO2). It was shown that the addition of silver based catalysts (Ag, Ag2O, Ag2CO3) into the carbon-carbonate slurry enhanced the performance of the HDCFC....

  16. Direct template synthesis of mesoporous carbon and its application to supercapacitor electrodes

    A direct templating method which is facile, inexpensive and suitable for the large scale production of mesoporous carbon is reported herein. A meso-structure surfactant/silicate template was made in a solution phase and resorcinol-formaldehyde as a carbon precursor was incorporated into the template solution. After aging, carbonization and hydrofluoric acid (HF) etching, mesoporous carbon was obtained. Using X-ray diffraction, scanning and transmission electron microscopy and nitrogen sorption, the synthesis mechanism of the mesoporous carbon was elucidated. According to the small angle X-ray scattering measurements, the surface became smoother after the removal of the silica, indicating that the silica was mostly located at the pore surface of the carbon. Also, the calculation of the pore volume demonstrated that the silica was transferred into the pores of the carbon without structural collapse during HF etching. When the prepared mesoporous carbon was applied to a supercapacitor electrode, the rectangular shape of the cyclic voltammogram was less collapsed, even at a high scan rate, which is indicative of its high rate capability. This was due to the low resistance of the electrolyte in the pores (3.8 Ω cm2), which was smaller than that of conventional activated carbon electrodes and even comparable to that of ordered mesoporous carbon electrodes. This improved performance was probably due to the well developed mesoporosity and high pore connectivity of the prepared mesoporous carbon.

  17. Effect of Molding Press Direction on Properties of Periclase-spinel-carbon Brick

    YANG Ding'ao; YU Zhiming; CHEN Shufeng; ZHANG Zunyu

    2004-01-01

    The effect of press direction on the thermal expansion, slag resistance, etc. of periclase-spinel-carbon brick has been studied in this article. The results show that the therma1 expansion rate in the direction parallel to the press axis is larger than that in the direction perpendicular to the press axis and the slag resistance in the direction parallel to the press axis is much better than that in the perpendicular direction. The directional distribution of graphite in the specimen is observed with the microscope.

  18. Direct effects of increasing carbon dioxide on vegetation

    Strain, B R; Cure, J D [eds.

    1985-12-01

    CO/sub 2/ is an essential environmental resource. It is required as a raw material of the orderly development of all green plants. As the availability of CO/sub 2/ increases, perhaps reaching two or three times the concentration prevailing in preindustrial times, plants and all other organisms dependent on them for food will be affected. Humans are releasing a gaseous fertilizer into the global atmosphere in quantities sufficient to affect all life. This volume considers the direct effects of global CO/sub 2/ fertilization on plants and thus on all other life. Separate abstracts have been prepared for individual papers. (ACR)

  19. Direct Observation of Molecular Oxygen Production from Carbon Dioxide

    Larimian, Seyedreza; Mai, Sebastian; Marquetand, Philipp; González, Leticia; Baltuška, Andrius; Kitzler, Markus; Xie, Xinhua

    2016-01-01

    Oxygen ($O_2$) is one of the most important elements required to sustain life. The concentration of $O_2$ on Earth has been accumulated over millions of years and has a direct connection with that of $CO_2$. Further, $CO_2$ plays an important role in many other planetary atmospheres. Therefore, molecular reactions involving $CO_2$ are critical for studying the atmospheres of such planets. Existing studies on the dissociation of $CO_2$ are exclusively focused on the C--O bond breakage. Here we report first experiments on the direct observation of molecular Oxygen formation from $CO_2$ in strong laser fields with a reaction microscope. Our accompanying simulations suggest that $CO_2$ molecules may undergo bending motion during and after strong-field ionization which supports the molecular Oxygen formation process. The observation of the molecular Oxygen formation from $CO_2$ may trigger further experimental and theoretical studies on such processes with laser pulses, and provide hints in studies of the $O_2$ an...

  20. Collector Failures on 350 MHz, 1.2 MW CW Klystrons at the Low Energy Demonstration Accelerator (LEDA)

    Rees, D; Bradley, J

    2000-01-01

    We are currently operating the front end of the accelerator production of tritium (APT) accelerator, a 7 MeV radio frequency quadrapole (RFQ) using three, 1.2 MW CW klystrons. These klystrons are required and designed to dissipate the full beam power in the collector. The klystrons have less than 1500 operational hours. One collector has failed and all collectors are damaged. This paper will discuss the damage and the difficulties in diagnosing the cause. The collector did not critically fail. Tube operation was still possible and the klystron operated up to 70% of full beam power with excellent vacuum. The indication that finally led us to the collector failure was variable emission. This information will be discussed. A hydrophonic system was implemented to diagnose collector heating. The collectors are designed to allow for mixed-phase cooling and with the hydrophonic test equipment we are able to observe: normal, single-phase cooling, mixed-phase cooling, and a hard boil. These data will be presented. The...

  1. Direct measurement of carbon enrichment in the incomplete bainite transformation in Mo added low carbon steels

    The overall kinetics and carbon enrichment in austenite during the incomplete isothermal bainite transformation in Fe–0.1C–1.5Mn–(0, 0.03, 0.3, 0.5, 1)Mo (mass%) alloys were investigated with quantitative metallography and Electron Probe Microanalysis in the transformation temperature range of 773–873 K. The incomplete transformation appears at 823–873 K when Mo addition exceeds 0.3 mass%; at 773 K substantial carbide precipitation accompanies bainite transformation and no transformation stasis is observed. Transformed fractions in the stasis stage are hardly affected by prior austenite grain size. Carbon concentrations in austenite in the stasis stage are lower than T0 line and decrease with the increase of Mo addition and temperature. T0′ limit, solute drag and WBs limit theories are used to examine the experimentally measured carbon concentration limits in austenite, and their respective flaws are pointed out

  2. Direct Conversion of Carbon Fuels in a Molten Carbonate Fuel Cell

    Cherepy, N J; Fiet, K J; Krueger, R; Jankowski, A F; Cooper, J F

    2004-01-28

    Anodes of elemental carbon may be discharged in a galvanic cell using a molten carbonate electrolyte, a nickel-foam anode-current collector, and a porous nickel air cathode to achieve power densities of 40-100 mW/cm{sup 2}. We report cell and anode polarization, surface area, primary particle size and a crystallization index for nine particulate carbon samples derived from fuel oil, methane, coal, charred biological material and petroleum coke. At 800 C, current densities of 50-125 mA/cm{sup 2} were measured at a representative cell voltage of 0.8 V. Power densities for cells with two carbon-anode materials were found to be nearly the same on scales of 2.8- and 60 cm{sup 2} active area. Constant current operation of a small cell was accompanied by constant voltage during multiple tests of 10-30 hour duration. Cell voltage fell off after the carbon inventory was consumed. Three different cathode structures are compared, indicating that an LLNL fabricated porous nickel electrode with <10 {micro}m pores provides improved rates compared with nickel foam with 100-300 {micro}m pores. Petroleum coke containing substantial sulfur and ash discharges at a slightly lower rate than purified petroleum coke. The sulfur leads to degradation of the anode current collector over time. A conceptual model for electrochemical reactivity of carbon is presented which indicates the importance of (1) bulk lattice disorder, which continually provides surface reactive sites during anodic dissolution and (2) electrical conductivity, which lowers the ohmic component of anode polarization.

  3. Fabrication of three dimensional carbon nanotube foam by direct conversion carbon dioxide and its application in supercapacitor

    Highlights: • 3D carbon nanotube foams (CNTF) are obtained by directly conversing CO2. • As-grown CNTF can be used as a current collector for supercapacitors to substitute metal one. • Binder-free porous Ni(OH)2 nanosheet array are fabricated on the CNTF. • Enhanced electrical conductivity leads to excellent electrochemical performance. • The present method maybe a general strategy for fabricating other 3D macroscopic structures. - Abstract: Carbon nanotube (CNT) is an ideal electrode material for supercapacitors due to its low electronic and ionic charge-transfer resistances. Here we reported the direct synthesis 3D carbon nanotube foam (CNTF) macrostructure by conversing CO2 through template-directed chemical vapour deposition. Using this unique network structure and outstanding electrical and mechanical properties of the CNTF, as an example, we demonstrate the excellent electrochemical properties of Ni(OH)2/CNTF composite. Based on the total mass of the electrode, as high as specific capacitances of 259 and 131 F g−1 are obtained at current densities of 0.5 and 10 A g−1 respectively. Meanwhile, the electrode also exhibits excellent long cycle life along with 94.0% specific capacitance retained after 2000 cycle tests. Moreover, this template-directed CVD technique is versatile and scalable, and can be a general strategy for fabricating a broad class of three-dimensional macroscopic structures of determined shapes with excellent properties and new uses

  4. Comprehensive analysis of direct aqueous mineral carbonation using dissolution enhancing organic additives.

    Bonfils, Benjamin; Julcour-Lebigue, Carine; Guyot, François; Bodénan, Françoise; Chiquet, Pierre; Bourgeois, Florent

    2012-01-01

    Direct aqueous mineral carbonation using organic anions has been presented by many as a promising strategy for mineral carbonation, on the basis that additives such as oxalate increase the rate and extent of dissolution of magnesium silicates several folds. Through geochemical modelling and detailed solid characterization, this paper discusses and extends our current understanding of this process. The role of disodium oxalate as a dissolution enhancing agent for olivine is thoroughly examined...

  5. Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes

    We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs) on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR) at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

  6. Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes

    Mohd Ambri Mohamed, Nobuhito Inami, Eiji Shikoh, Yoshiyuki Yamamoto, Hidenobu Hori and Akihiko Fujiwara

    2008-01-01

    Full Text Available We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

  7. Direct Experimental Evidence of Exciton-Phonon Bound States in Carbon Nanotubes

    Plentz, Flavio; Henrique B. Ribeiro; Jorio, Ado; Pimenta, Marcos A.; Strano, Michael S.

    2005-01-01

    We present direct experimental observation of exciton-phonon bound states in the photoluminescence excitation spectra of isolated single walled carbon nanotubes in aqueous suspension. The photoluminescence excitation spectra from several distinct single-walled carbon nanotubes show the presence of at least one sideband related to the tangential modes, lying {200 meV} above the main absorption/emission peak. Both the energy position and line shapes of the sidebands are in excellent agreement w...

  8. Efficiency of non-optimized direct carbon fuel cell with molten alkaline electrolyte fueled by carbonized biomass

    Kacprzak, A.; Kobyłecki, R.; Włodarczyk, R.; Bis, Z.

    2016-07-01

    The direct carbon fuel cells (DCFCs) belong to new generation of energy conversion devices that are characterized by much higher efficiencies and lower emission of pollutants than conventional coal-fired power plants. In this paper the DCFC with molten hydroxide electrolyte is considered as the most promising type of the direct carbon fuel cells. Binary alkali hydroxide mixture (NaOH-LiOH, 90-10 mol%) is used as electrolyte and the biochar of apple tree origin carbonized at 873 K is applied as fuel. The performance of a lab-scale DCFC with molten alkaline electrolyte is investigated and theoretical, practical, voltage, and fuel utilization efficiencies of the cell are calculated and discussed. The practical efficiency is assessed on the basis of fuel HHV and LHV and the values are estimated at 40% and 41%, respectively. The average voltage efficiency is calculated as roughly 59% (at 0.65 V) and it is in a relatively good agreement with the values obtained by other researchers. The calculated efficiency of fuel utilization exceeds 95% thus indicating a high degree of carbon conversion into the electric power.

  9. Transmission welding of carbon nanocomposites with direct-diode and Nd:YAG solid state lasers

    Dosser, Larry; Hix, Ken; Hartke, Kevin; Vaia, Richard; Li, Mingwei

    2004-07-01

    Carbon nanocomposites consist of thermoset or thermoplastic materials filled with carbon nano-particles (nanotubes, bucky balls, etc.). This new and innovative group of materials offers many advantages over standard polymers such as electrical/thermal conductivity and improved structural properties. In the current study, direct diode and Nd:YAG solid-state lasers were used to transmission weld -carbon nanocomposite materials. The experimentation was focused on exploiting the infrared absorbing characteristics of the carbon nanocomposites. Polyetheretherketone (PEEK) based polymer was used in the initial experimentation to quantify weld strength. The experimentation included a complete analysis of the transmission characteristics of the base polymer at 810 nm and 1,064 nm wavelengths, an optical microscope view of the weld cross-section, and transmission welding experimentation. The transmission welding experimentation studied the relationship between average power, travel speed, and weld peel strength. A micro-channel welding experiment was also completed using a polycarbonate (PC) based polymer. The experimentation qualified the minimum feature size that could be joined. The resulsts show that the carbon nanocomposites can be welded in a similar way to carbon black filled materials. The carbon nanocomposites exhibited higher peel strengths at lower average laser power at both 810 and 1064 nm. The carbon nanocomposite material exhibited a unique characteristic of being able to be machined and welded by the same laser wavelength.

  10. Synthesis and electrochemical capacitive properties of nitrogen-doped porous carbon micropolyhedra by direct carbonization of zeolitic imidazolate framework-11

    Hao, Fei; Li, Li; Zhang, Xiaohua, E-mail: mickyxie@hnu.edu.cn; Chen, Jinhua, E-mail: chenjinhua@hnu.edu.cn

    2015-06-15

    Highlights: • Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were prepared from ZIF-11. • The activated N-PCMPs with fused KOH (N-PCMPs-A) have high specific surface area. • N-PCMPs-A exhibits high specific capacitance. • N-PCMPs-A reveals good cycling performance even at a high current density. - Abstract: Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were successfully prepared by direct carbonization of ZIF-11 polyhedra and further activated with fused KOH to obtain N-PCMPs-A. The morphology and microstructure of samples were examined by scanning electron microscopy, X-ray diffraction, and micropore and chemisorption analyzer. Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge method in 1.0 M H{sub 2}SO{sub 4} aqueous solution on a standard three-electrode system. Results show that, compared with N-PCMPs, N-PCMPs-A has higher specific surface area (2188 m{sup 2} g{sup −1}) and exhibits improved electrochemical capacitive properties (307 F g{sup −1} at 1.0 A g{sup −1}). The mass specific capacitance of N-PCMPs-A is also higher than that of most MOF-derived carbons, some carbide-derived carbons and carbon aerogel-derived carbons. In addition, the capacitance of the N-PCMPs-A retains 90% after 4000 cycles even at a high current density of 10 A g{sup −1}. These imply that N-PCMPs-A is the promising materials for the construction of a high-performance supercapacitor.

  11. Synthesis and electrochemical capacitive properties of nitrogen-doped porous carbon micropolyhedra by direct carbonization of zeolitic imidazolate framework-11

    Highlights: • Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were prepared from ZIF-11. • The activated N-PCMPs with fused KOH (N-PCMPs-A) have high specific surface area. • N-PCMPs-A exhibits high specific capacitance. • N-PCMPs-A reveals good cycling performance even at a high current density. - Abstract: Nitrogen-doped porous carbon micropolyhedra (N-PCMPs) were successfully prepared by direct carbonization of ZIF-11 polyhedra and further activated with fused KOH to obtain N-PCMPs-A. The morphology and microstructure of samples were examined by scanning electron microscopy, X-ray diffraction, and micropore and chemisorption analyzer. Electrochemical properties were characterized by cyclic voltammetry and galvanostatic charge/discharge method in 1.0 M H2SO4 aqueous solution on a standard three-electrode system. Results show that, compared with N-PCMPs, N-PCMPs-A has higher specific surface area (2188 m2 g−1) and exhibits improved electrochemical capacitive properties (307 F g−1 at 1.0 A g−1). The mass specific capacitance of N-PCMPs-A is also higher than that of most MOF-derived carbons, some carbide-derived carbons and carbon aerogel-derived carbons. In addition, the capacitance of the N-PCMPs-A retains 90% after 4000 cycles even at a high current density of 10 A g−1. These imply that N-PCMPs-A is the promising materials for the construction of a high-performance supercapacitor

  12. Factors affecting the precipitation of pure calcium carbonate during the direct aqueous carbonation of flue gas desulfurization gypsum

    The mineral carbonation of FGD (flue gas desulfurization) gypsum was carried out through CO2 sorption into ammonia solution containing FGD gypsum. High-purity calcium carbonate was precipitated from DCC (dissolved calcium carbonate) solution which was extracted during the induction period. The factors affecting the preparation of pure calcium carbonate were examined under the following conditions: CO2 flow rate (1–3 L/min), ammonia content (4–12%), and S/L (solid-to-liquid) ratio (5–300 g/L). X-Ray diffraction study revealed that the PCC (precipitated calcium carbonate) was round-shaped vaterite. The induction time for PCC decreased as the CO2 flow rate increased. The maximum formation efficiency for pure PCC was seen to increase linearly with the ammonia content. The formation efficiency for pure PCC was the highest (90%) for S/L ratio of 5 g/L but it decreased as S/L ratio increased. On the other hand, S/L ratio didn't affect the maximum solubility limit of DCC. It is believed that the pure PCC would add an economic value to the FGD gypsum carbonation for industrial CO2 sequestration. - Highlights: • Pure and white CaCO3 was synthesized using induction period during direct carbonation of FGD gypsum. • Its formation efficiency was increased with ammonia content but decreased with solid-to-liquid ratio. • This method is expected to extend to other industrial CO2 sequestration for the enhanced economic value of precipitated CaCO3

  13. Highly porous activated carbons prepared from carbon rich Mongolian anthracite by direct NaOH activation

    Byamba-Ochir, Narandalai; Shim, Wang Geun; Balathanigaimani, M. S.; Moon, Hee

    2016-08-01

    Highly porous activated carbons (ACs) were prepared from Mongolian raw anthracite (MRA) using sodium hydroxide as an activation agent by varying the mass ratio (powdered MRA/NaOH) as well as the mixing method of chemical agent and powdered MRA. The specific BET surface area and total pore volume of the prepared MRA-based activated carbons (MACs) are in the range of 816-2063 m2/g and of 0.55-1.61 cm3/g, respectively. The pore size distribution of MACs show that most of the pores are in the range from large micropores to small mesopores and their distribution can be controlled by the mass ratio and mixing method of the activating agent. As expected from the intrinsic property of the MRA, the highly graphitic surface morphology of prepared carbons was confirmed from Raman spectra and transmission electron microscopy (TEM) studies. Furthermore the FTIR and XPS results reveal that the preparation of MACs with hydrophobic in nature is highly possible by controlling the mixing conditions of activating agent and powdered MRA. Based on all the results, it is suggested that the prepared MACs could be used for many specific applications, requiring high surface area, optimal pore size distribution, proper surface hydrophobicity as well as strong physical strength.

  14. Ionic Liquid Directed Mesoporous Carbon Nanoflakes as an Effiencient Electrode material

    Kong, Lirong; Chen, Wei

    2015-01-01

    Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials. PMID:26656464

  15. Predicting and Evaluating the Effectiveness of Ocean Carbon Sequestration by Direct Injection

    Caldeira, K; Herzog, H J; Wickett, M E

    2001-04-24

    Direct injection of CO{sub 2} into the ocean is a potentially effective carbon sequestration strategy. Therefore, we want to understand the effectiveness of oceanic injection and develop the appropriate analytic framework to allow us to compare the effectiveness of this strategy with other carbon management options. Here, after a brief review of direct oceanic injection, we estimate the effectiveness of ocean carbon sequestration using one dimensional and three dimensional ocean models. We discuss a new measure of effectiveness of carbon sequestration in a leaky reservoir, which we denote sequestration potential. The sequestration potential is the fraction of global warning cost avoided by sequestration in a reservoir. We show how these measures apply to permanent sequestration and sequestration in leaky reservoirs, such as the oceans, terrestrial biosphere, and some geologic formations. Under the assumptions of a constant cost of carbon emission and a 4% discount rate, injecting 900 m deep in the ocean avoids {approx}90% of the global warming cost associated with atmospheric emission; an injection 1700 m deep would avoid > 99 % of the global warming cost. Hence, for discount rates in the range commonly used by commercial enterprises, oceanic direct injection may be nearly as economically effective as permanent sequestration at avoiding global warming costs.

  16. Effect of Initial Principal Stress Direction on the Dynamic Characteristics of Carbonate Sand

    Yu Haizhen; Zhao Wenguang; Wang Ren; Li Jianguo; He Yang

    2005-01-01

    The dynamic characteristics of carbonate sand under wave loads are very important for constructions on the ocean floor. The initial principal stress direction has been known to exert some influence on the dynamic characteristics of sand during cyclic loading. In an effort to investigate this aspect of the problem, several series of cyclic undrained tests were carried out on a saturated and loose sample of carbonate sand using a geotechnical static and dynamic universal triaxial shear apparatus. In this test apparatus, a hollow cylindrical sand specimen is subjected to a simultaneous application of both triaxial and torsional modes of shear stresses, which brings about the continuous rotation of principal stress axes. The test results indicated that the initial principal stress direction has a considerable influence on the dynamic strength of loose carbonate sand and with the increase of initial orientation of principal stress, dynamic strength will be reduced, the cyclic pore pressure increased, but the residual pore pressure reduced.

  17. SPOUTED BED ELECTRODES (SBE) FOR DIRECT UTILIZATION OF CARBON IN FUEL CELLS

    J.M. Calo

    2004-12-01

    This Phase I project was focused on an investigation of spouted bed particulate electrodes for the direct utilization of solid carbon in fuel cells. This approach involves the use of a circulating carbon particle/molten carbonate slurry in the cell that provides a few critical functions: it (1) fuels the cell continuously with entrained carbon particles; (2) brings particles to the anode surfaces hydrodynamically; (3) removes ash from the anode surfaces and the cell hydrodynamically; (4) provides a facile means of cell temperature control due to its large thermal capacitance; (5) provides for electrolyte maintenance and control in the electrode separator(s); and (6) can (potentially) improve carbon conversion rates by ''pre-activating'' carbon particle surfaces via formation of intermediate oxygen surface complexes in the bulk molten carbonate. The approach of this scoping project was twofold: (1) adaptation and application of a CFD code, originally developed to simulate particle circulation in spouted bed electrolytic reactors, to carbon particle circulation in DCFC systems; and (2) experimental investigation of the hydrodynamics of carbon slurry circulation in DCFC systems using simulated slurry mixtures. The CFD model results demonstrated that slurry recirculation can be used to hydrodynamically feed carbon particles to anode surfaces. Variations of internal configurations were investigated in order to explore effects on contacting. It was shown that good contacting with inclined surfaces could be achieved even when the particles are of the same density as the molten carbonate. The use of CO{sub 2} product gas from the fuel cell as a ''lift-gas'' to circulate the slurry was also investigated with the model. The results showed that this is an effective method of slurry circulation; it entrains carbon particles more effectively in the draft duct and produces a somewhat slower recirculation rate, and thus higher residence

  18. Palladium and palladium-tin supported on multi wall carbon nanotubes or carbon for alkaline direct ethanol fuel cell

    Geraldes, Adriana Napoleão; Furtunato da Silva, Dionisio; Martins da Silva, Júlio César; Antonio de Sá, Osvaldo; Spinacé, Estevam Vitório; Neto, Almir Oliveira; Coelho dos Santos, Mauro

    2015-02-01

    Pd and PdSn (Pd:Sn atomic ratios of 90:10), supported on Multi Wall Carbon Nanotubes (MWCNT) or Carbon (C), are prepared by an electron beam irradiation reduction method. The obtained materials are characterized by X-Ray diffraction (XRD), Energy dispersive X-ray analysis (EDX), Transmission electron Microscopy (TEM) and Cyclic Voltammetry (CV). The activity for ethanol electro-oxidation is tested in alkaline medium, at room temperature, using Cyclic Voltammetry and Chronoamperometry (CA) and in a single alkaline direct ethanol fuel cell (ADEFC), in the temperature range of 60-90 °C. CV analysis finds that Pd/MWCNT and PdSn/MWCNT presents onset potentials changing to negative values and high current values, compared to Pd/C and PdSn/C electrocatalysts. ATR-FTIR analysis, performed during the CV, identifies acetate and acetaldehyde as principal products formed during the ethanol electro-oxidation, with low conversion to CO2. In single fuel cell tests, at 85 °C, using 2.0 mol L-1 ethanol in 2.0 mol L-1 KOH solutions, the electrocatalysts supported on MWCNT, also, show higher power densities, compared to the materials supported on carbon: PdSn/MWCNT, presents the best result (36 mW cm-2). The results show that the use of MWCNT, instead of carbon, as support, plus the addition of small amounts of Sn to Pd, improves the electrocatalytic activity for Ethanol Oxidation Reaction (EOR).

  19. Direct Electrochemical Oxidation of NADPH at a Low Potential on the Carbon Nanotube Modified Glassy Carbon Electrode

    CHEN, Jing(陈静); CAI, Chen-Xin(蔡称心)

    2004-01-01

    NADPH can be directly oxidized on a carbon nanotube modified glassy carbon (CNT/GC) electrode in phosphate buffer solution (pH=6.0) with a diminution of the overpotential of more than 700 mV. The anodic peak currents increase linearly with the increase of concentration of NADPH in the range of 5×10-7 to 1×10-3 mol/L with a detection limit of about 1×10-7 mol/L. The CNT/GC electrode exhibits high sensitivity, low potential and stability in detecting NADPH and thus might be used in biosensors to study the electrocatalytic reaction of important dehydrogenase-based biological systems.

  20. Direct Laser Writing of Porous-Carbon/Silver Nanocomposite for Flexible Electronics.

    Rahimi, Rahim; Ochoa, Manuel; Ziaie, Babak

    2016-07-01

    In this Research Article, we demonstrate a facile method for the fabrication of porous-carbon/silver nanocomposites using direct laser writing on polymeric substrates. Our technique uses a combination of CO2 laser-induced carbonization and selective silver deposition on a polyimide sheet to create flexible highly conductive traces. The localized laser irradiation selectively converts the polyimide to a highly porous and conductive carbonized film with superhydrophilic wettability. The resulting pattern allows for selective trapping of aqueous silver ionic ink solutions into the carbonized regions, which are converted to silver nanoparticle fillers upon an annealing step. Elemental and surface morphology analysis via XRD and SEM reveals a uniform coating of Ag nanoparticles on the porous carbon. The Ag/C composite lowers the sheet resistance of the original laser carbonized polyimide from 50 to 0.02 Ω/□. The resulting patterns are flexible and electromechanically robust with less than 0.6 Ω variation in resistance after >15000 bending flexion cycles at a radius of curvature of 5 mm. Furthermore, using this technique, we demonstrate the fabrication of a wireless resonant pressure sensor capable of detecting pressures ranging from 0 to 97 kPa with an average sensitivity of -26 kHz/kPa. PMID:27246534

  1. PREPARATION OF WC-Co POWDER BY DIRECT REDUCTION AND CARBONIZATION

    Zhonglai Yi; Gangqin Shao; Xinglong Duan; Peng Sun; Xiaoliang Shi; Zhen Xiong; Jingkun Guo

    2005-01-01

    A new approach to produce superfine WC-Co powder by direct reduction and carbonization is proposed.Water-soluble salts containing W and Co were used as raw materials. Tungsten and cobalt oxide powder (CoWO4/WO3)was first formed by a spray-pyrolysis technique, which was then mixed with carbon black and converted to WC-Co composite powder at 950℃ for 4 h in N2 atmosphere. The resulting powder has a particle size of 100-300 nm.

  2. Direct electron transfer from glucose oxidase immobilized on a nano-porous glassy carbon electrode

    Haghighi, Behzad, E-mail: haghighi@iasbs.ac.ir [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Gava Zang, Zanjan (Iran, Islamic Republic of); Tabrizi, Mahmoud Amouzadeh [Department of Chemistry, Institute for Advanced Studies in Basic Sciences, P.O. Box 45195-1159, Gava Zang, Zanjan (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A direct electron transfer reaction of glucose oxidase was observed on the surface of a nano-porous glassy carbon electrode. > A pair of well-defined and reversible redox peaks was observed at the formal potential of approximately -0.439 V. > The apparent electron transfer rate constant was measured to be 5.27 s{sup -1}. > A mechanism for the observed direct electron transfer reaction was proposed, which consists of a two-electron and a two-proton transfer. - Abstract: A pair of well-defined and reversible redox peaks was observed for the direct electron transfer (DET) reaction of an immobilized glucose oxidase (GOx) on the surface of a nano-porous glassy carbon electrode at the formal potential (E{sup o}') of -0.439 V versus Ag/AgCl/saturated KCl. The electron transfer rate constant (k{sub s}) was calculated to be 5.27 s{sup -1}. The dependence of E{sup o}' on pH indicated that the direct electron transfer of the GOx was a two-electron transfer process, coupled with two-proton transfer. The results clearly demonstrate that the nano-porous glassy carbon electrode is a cost-effective and ready-to-use scaffold for the fabrication of a glucose biosensor.

  3. Predominating stable adsorption and direct electrochemistry of glucose oxidase on carbon nanotubes by oxygen-containing groups

    Chun Hai Yang; Cheng Guo Hu; Sheng Shui Hu

    2007-01-01

    Stable adsorption and direct electrochemistry of glucose oxidase (GOx) occurred on nitric acid (HNO3)-treated multi-walled carbon nanotubes (MWNTs) instead of as-received MWNTs, demonstrating the critical roles of oxygen-containing groups in stable adsorption and direct electrochemistry of GOx on carbon nanotubes (CNTs).

  4. Direct measurement of hydrogen adsorption in carbon nanotubes/nanofibers by elastic recoil detection

    Physi- or chemi-sorption of hydrogen in solid materials offers a viable medium for hydrogen storage since the concentration of hydrogen can exceed that in its gaseous form at high compression. Due to their unique architecture, carbon nanotubes are potentially an excellent carbon-based adsorbent for hydrogen. In this work, we report direct measurements of hydrogen adsorption using elastic recoil detection analysis in single-walled, double-walled, and multi-walled nanotubes, as well as carbon nanofibers. Results are presented for hydrogen adsorption treatment at ambient temperature and above, where chemical rather than physical adsorption is anticipated. The results show that the concentration of hydrogen in all samples over the range of conditions investigated is below 1 wt.%, which is well below that required for a viable storage media

  5. Application of infiltrated LSCM-GDC oxide anode in direct carbon/coal fuel cells.

    Yue, Xiangling; Arenillas, Ana; Irvine, John T S

    2016-08-15

    Hybrid direct carbon/coal fuel cells (HDCFCs) utilise an anode based upon a molten carbonate salt with an oxide conducting solid electrolyte for direct carbon/coal conversion. They can be fuelled by a wide range of carbon sources, and offer higher potential chemical to electrical energy conversion efficiency and have the potential to decrease CO2 emissions compared to coal-fired power plants. In this study, the application of (La, Sr)(Cr, Mn)O3 (LSCM) and (Gd, Ce)O2 (GDC) oxide anodes was explored in a HDCFC system running with two different carbon fuels, an organic xerogel and a raw bituminous coal. The electrochemical performance of the HDCFC based on a 1-2 mm thick 8 mol% yttria stabilised zirconia (YSZ) electrolyte and the GDC-LSCM anode fabricated by wet impregnation procedures was characterized and discussed. The infiltrated oxide anode showed a significantly higher performance than the conventional Ni-YSZ anode, without suffering from impurity formation under HDCFC operation conditions. Total polarisation resistance (Rp) reached 0.8-0.9 Ω cm(2) from DCFC with an oxide anode on xerogel and bituminous coal at 750 °C, with open circuit voltage (OCV) values in the range 1.1-1.2 V on both carbon forms. These indicated the potential application of LSCM-GDC oxide anode in HDCFCs. The chemical compatibility of LSCM/GDC with carbon/carbonate investigation revealed the emergence of an A2BO4 type oxide in place of an ABO3 perovskite structure in the LSCM in a reducing environment, due to Li attack as a result of intimate contact between the LSCM and Li2CO3, with GDC being stable under identical conditions. Such reaction between LSCM and Li2CO3 was not observed on a LSCM-YSZ pellet treated with Li-K carbonate in 5% H2/Ar at 700 °C, nor on a GDC-LSCM anode after HDCFC operation. The HDCFC durability tests of GDC-LSCM oxide on a xerogel and on raw bituminous coal were performed under potentiostatic operation at 0.7 V at 750 °C. The degradation mechanisms were

  6. Direct Electrochemistry of Glucose Oxidase on Novel Free-Standing Nitrogen-Doped Carbon Nanospheres@Carbon Nanofibers Composite Film

    Zhang, Xueping; Liu, Dong; Li, Libo; You, Tianyan

    2015-05-01

    We have proposed a novel free-standing nitrogen-doped carbon nanospheres@carbon nanofibers (NCNSs@CNFs) composite film with high processability for the investigation of the direct electron transfer (DET) of glucose oxidase (GOx) and the DET-based glucose biosensing. The composites were simply prepared by controlled thermal treatment of electrospun polypyrrole nanospheres doped polyacrylonitrile nanofibers (PPyNSs@PAN NFs). Without any pretreatment, the as-prepared material can directly serve as a platform for GOx immobilization. The cyclic voltammetry of immobilized GOx showed a pair of well-defined redox peaks in O2-free solution, indicating the DET of GOx. With the addition of glucose, the anodic peak current increased, while the cathodic peak current decreased, which demonstrated the DET-based bioelectrocatalysis. The detection of glucose based on the DET of GOx was achieved, which displayed high sensitivity, stability and selectivity, with a low detection limit of 2 μM and wide linear range of 12-1000 μM. These results demonstrate that the as-obtained NCNSs@CNFs can serve as an ideal platform for the construction of the third-generation glucose biosensor.

  7. Immobilization and direct electrochemistry of copper-containing enzymes on active carbon

    SUN Dongmei; CAI Chenxin; XING Wei; LU Tianhong

    2004-01-01

    Two typical and important copper-containing enzymes, laccase (Lac) and tyrosinase (Tyr), have been immobilized on the surface of active carbon with simple adsorption method. The cyclic voltammetric results indicated that the active carbon could promote the direct electron transfer of both Lac and Tyr and a pair of well-defined and nearly symmetric redox peaks appeared on the cyclic voltammograms of Lac or Tyr with the formal potential, E0′, independent on the scan rate. The further experimental results showed that the immobilized copper-containing oxidase displayed an excellent electrocatalytic activity to the electrochemical reduction of O2. The immobilization method presented here has several advantages, such as simplicity, easy to operation and keeping good activity of enzyme etc., and could be further used to study the direct electrochemistry of other redox proteins and enzymes and fabricate the catalysts for biofuel cell.

  8. Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode

    Yongming Zhang

    2010-02-01

    Full Text Available The novel highly ordered mesoporous carbon (known as FDU-15, prepared by the organic-organic self-assembly method was been used for first time for the immobilization of hemoglobin (Hb and its bioelectrochemical properties were studied. The resulting Hb/FDU-15 film provided a favorable microenvironment for Hb to perform direct electron transfers at the electrode. The immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide. The results demonstrate that mesoporous carbon FDU-15 can improve the Hb loading with retention of its bioactivity and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility. Our present study may provide an alternative way for the construction of nanostructure biofunctional surfaces and pave the way for its application to biosensors.

  9. Biocatalytic anode for glucose oxidation utilizing carbon nanotubes for direct electron transfer with glucose oxidase

    Vaze, Abhay; Hussain, Nighat; Tang, Chi [Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060 (United States); Leech, Donal [School of Chemistry, National University of Ireland, Galway (Ireland); Rusling, James [Department of Chemistry, University of Connecticut, Storrs, CT 06269-3060 (United States); Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032 (United States); School of Chemistry, National University of Ireland, Galway (Ireland)

    2009-10-15

    Covalently linked layers of glucose oxidase, single-wall carbon nanotubes and poly-L-lysine on pyrolytic graphite resulted in a stable biofuel cell anode featuring direct electron transfer from the enzyme. Catalytic response observed upon addition of glucose was due to electrochemical oxidation of FADH{sub 2} under aerobic conditions. The electrode potential depended on glucose concentration. This system has essential attributes of an anode in a mediator-free biocatalytic fuel cell. (author)

  10. Highly integrated CO2 capture and conversion: Direct synthesis of cyclic carbonates from industrial flue gas

    Barthel, Alexander

    2016-02-08

    Robust and selective catalytic systems based on early transition metal halides (Y, Sc, Zr) and organic nucleophiles were found able to quantitatively capture CO2 from diluted streams via formation of hemicarbonate species and to convert it to cyclic organic carbonates under ambient conditions. This observation was exploited in the direct and selective chemical fixation of flue gas CO2 collected from an industrial exhaust, affording high degrees of CO2 capture and conversion.

  11. Carbon total determination in U-Zr alloy by direct combustion and thermal conductivity detection techniques

    In CDTN has been developed nuclear fuel elements for research nuclear reactors. The chemical characterization of U-Zr alloy require several determinations and in special the total carbon analysis. The determination was carried out by direct combustion and thermal conductivity detection technique that is described in this work. Some comments about the fundamental principles involved in this technique are also presented. (author). 5 refs., 1 tab

  12. Carbon dynamics and changing winter conditions: a review of current understanding and future research directions

    Haei, M.; Laudon, H.

    2015-09-01

    Despite the important role of winters for northern ecosystems, it remains the least understood of all the seasons. Here, we summarize existing empirical studies on winter climate and carbon dynamics and highlight some important future research directions. The existing studies include field-scale snow-cover manipulation experiments representing extreme soil climate conditions, laboratory soil incubations studying the influential factors, and time-series of climate and carbon data showing long-term natural variations and existing trends. Most of the field and laboratory experiments indicate an increased soil organic carbon loss due to soil frost. Long-term data demonstrate temporal changes in winter CO2 efflux and its important contribution to the annual fluxes. A number of research priorities to improve our understanding of winter conditions include (i) ecosystem processes in the fall-winter and winter-spring shoulder seasons, (ii) extreme events, (iii) partitioning into organic- and inorganic carbon, (iv) carry-over effects of winter and growing season on each other, (v) long-term cumulative impacts, and (vi) improved winter process modelling. These areas of research would enable an improved understanding of the role of the snow covered period for carbon cycling, and provide a basis for more realistic models that include winter processes.

  13. Direct observation of hole transfer from semiconducting polymer to carbon nanotubes.

    Lan, Fei; Li, Guangyong

    2013-05-01

    Carbon nanotubes have been proven to play significant roles in polymer-based solar cells. However, there is intensive debate on whether carbon nanotube behaves as a donor or acceptor in the semiconducting polymer:carbon nanotube composite. In this paper, we report a direct observation via Kelvin probe force microscopy (KPFM) that single walled carbon nanotubes (SWNTs) behave as hole transporting channels in poly(3-hexylthiophene-2,5-diyl) (P3HT)/SWNT heterojunctions. By comparing the surface potential (SP) change of SWNT in dark and under illumination, we observed that electrons are blocked from SWNT while holes are transferred to SWNT. This observation can be well-explained by our proposed band alignment model of P3HT/SWNT heterojunction. The finding is further verified by hole mobility measurement using the space charge limited current (SCLC) method. SCLC results indicate that the existence of small amount of SWNT (wt 0.5%) promotes device hole mobility to around 15-fold, indicating SWNT act as hole transfer channel. Our finding of hole transporting behavior of SWNT in P3HT/SWNT blend will provide a useful guidance for enhancing the performance of polymer solar cells by carbon nanotubes. PMID:23574570

  14. Direct electron transfer of glucose oxidase on the carbon nanotube electrode

    CAI Chenxin; CHEN Jing; LU Tianhong

    2004-01-01

    The direct electron transfer of glucose oxidase (Gox) immobilized onto the surface of the carbon nanotube (CNT)-modified glassy carbon (CNT/GC) electrode is reported. The direct electron transfer rate of Gox is greatly enhanced when it was immobilized onto the surface of CNT/GC electrode. Cyclic voltammetric results show a pair of well-defined and nearly sym metric redox peaks, which corresponds to the direct electron transfer of Gox, with the formal potential (E0′), which is almost independent on the scan rates, of about -0.456 V (vs. SCE) in the phosphate buffer solution (pH 6.9). The apparent heterogeneous electron transfer rate constant (ks) of Gox at the CNT/GC electrode surface is estimated to be (1.74 ± 0.42) s-1, which is much higher than that reported previously. The dependence of E0′on solution pH indicates that the direct electron transfer of Gox is a two-electron-transfer coupled with two-proton-transfer reaction process. The experimental results also demonstrate that the immobilized Gox retains its bioelectrocatalytic activity toward the oxidation of glucose. The method presented here can be easily extended to obtain the direct electrochemistry of other enzymes or proteins.

  15. MODELING AND DESIGN FOR A DIRECT CARBON FUEL CELL WITH ENTRAINED FUEL AND OXIDIZER

    Alan A. Kornhauser; Ritesh Agarwal

    2005-04-01

    The novel molten carbonate fuel cell design described in this report uses porous bed electrodes. Molten carbonate, with carbon fuel particles and oxidizer entrained, is circulated through the electrodes. Carbon may be reacted directly, without gasification, in a molten carbonate fuel cell. The cathode reaction is 2CO{sub 2} + O{sub 2} 4e{sup -} {yields} 2CO{sub 3}{sup =}, while the anode reaction can be either C + 2CO{sub 3}{sup =} {yields} 3CO{sub 2} + 4e{sup -} or 2C + CO{sub 3}{sup =} {yields} 3CO + 2e{sup -}. The direct carbon fuel cell has an advantage over fuel cells using coal-derived synthesis gas in that it provides better overall efficiency and reduces equipment requirements. Also, the liquid electrolyte provides a means for transporting the solid carbon. The porous bed cell makes use of this carbon transport ability of the molten salt electrolyte. A one-dimensional model has been developed for predicting the performance of this cell. For the cathode, dependent variables are superficial O{sub 2} and CO{sub 2} fluxes in the gas phase, superficial O{sub 2} and CO{sub 2} fluxes in the liquid phase, superficial current density through the electrolyte, and electrolyte potential. The variables are related by correlations, from the literature, for gas-liquid mass transfer, liquid-solid mass transfer, cathode current density, electrode overpotential, and resistivity of a liquid with entrained gas. For the anode, dependent variables are superficial CO{sub 2} flux in the gas phase, superficial CO{sub 2} flux in the liquid phase, superficial C flux, superficial current density through the electrolyte, and electrolyte potential. The same types of correlations relate the variables as in the cathode, with the addition of a correlation for resistivity of a fluidized bed. CO production is not considered, and axial dispersion is neglected. The model shows behavior typical of porous bed electrodes used in electrochemical processes. Efficiency is comparable to that of

  16. Degradation Mechanism in a Direct Carbon Fuel Cell Operated with Demineralised Brown Coal

    Graphical abstract: - Highlights: • Degradation mechanism studied for demineralised coal in a direct carbon fuel cell. • Diffusion limited processes dominate the electrode polarisation losses in pure N2. • Major fuel cell performance loss occurred due to loss of carbon/anode contacts. • The anode retained its phase structure with minor other phases formed in operation. - Abstract: The performance of a demineralised and devolatilised coal from the Morwell mine in the Latrobe Valley, Victoria, has been investigated in a direct carbon fuel cell (DCFC) operated at 850 °C. The focus of the investigation has been on understanding degradation issues as a function of time involving a sequence of electrochemical impedance spectroscopy and voltage-current characteristic. Diffusion limited processes dominate the electrode polarisation losses in pure N2 atmosphere, however, these decrease substantially in the presence of CO2 as the anode chamber purge gas, due to in situ generation of fuel species by the reaction of CO2 with carbon. Post-mortem analysis of anode by SEM and XRD revealed only a minor degradation due to its reduction, particle agglomeration as well as the formation of small quantity of new phases. However, major fuel cell performance degradation (increase of ohmic resistive and electrode polarisation losses) occurred due to loss of carbon/anode contacts and a reduction in the electron-conducting pathways as the fuel was consumed. The investigations revealed that the demineralised coal char can be used as a viable fuel for DCFC, however, further developments on anode materials and fuel feed mechanism would be required to achieve long-term sustained performance

  17. Application of N-doped graphene modified carbon ionic liquid electrode for direct electrochemistry of hemoglobin

    Nitrogen-doped graphene (NG) was synthesized and used for the investigation on direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode as the substrate electrode. Due to specific characteristics of NG such as excellent electrocatalytic property and large surface area, direct electron transfer of Hb was realized with enhanced electrochemical responses appearing. Electrochemical behaviors of Hb on the NG modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode exhibited excellent electrocatalytic reduction activity toward different substrates, such as trichloroacetic acid and H2O2, with wider dynamic range and lower detection limit. These findings show that NG can be used for the preparation of chemically modified electrodes with improved performance and has potential applications in electrochemical sensing. - Graphical abstract: The utilization of N-doped graphene enables direct electrochemistry of hemoglobin with a pair of well-defined redox peaks appearing. - Highlights: • Nitrogen-doped graphene (NG) was synthesized by a solvothermal method. • NG was used for the investigation on direct electrochemistry of hemoglobin with carbon ionic liquid electrode. • The Hb modified electrode exhibited excellent electrocatalytic activity toward different substrates

  18. Application of N-doped graphene modified carbon ionic liquid electrode for direct electrochemistry of hemoglobin

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Dong, Lifeng, E-mail: donglifeng@qust.edu.cn [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Deng, Ying; Yu, Jianhua [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Wencheng [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Zhu, Qianqian [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China)

    2014-06-01

    Nitrogen-doped graphene (NG) was synthesized and used for the investigation on direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode as the substrate electrode. Due to specific characteristics of NG such as excellent electrocatalytic property and large surface area, direct electron transfer of Hb was realized with enhanced electrochemical responses appearing. Electrochemical behaviors of Hb on the NG modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode exhibited excellent electrocatalytic reduction activity toward different substrates, such as trichloroacetic acid and H{sub 2}O{sub 2}, with wider dynamic range and lower detection limit. These findings show that NG can be used for the preparation of chemically modified electrodes with improved performance and has potential applications in electrochemical sensing. - Graphical abstract: The utilization of N-doped graphene enables direct electrochemistry of hemoglobin with a pair of well-defined redox peaks appearing. - Highlights: • Nitrogen-doped graphene (NG) was synthesized by a solvothermal method. • NG was used for the investigation on direct electrochemistry of hemoglobin with carbon ionic liquid electrode. • The Hb modified electrode exhibited excellent electrocatalytic activity toward different substrates.

  19. Direct growth and patterning of multilayer graphene onto a targeted substrate without an external carbon source.

    Kang, Dongseok; Kim, Won-Jun; Lim, Jung Ah; Song, Yong-Won

    2012-07-25

    Using only a simple tube furnace, we demonstrate the synthesis of patterned graphene directly on a designed substrate without the need for an external carbon source. Carbon atoms are absorbed onto Ni evaporator sources as impurities, and incorporated into catalyst layers during the deposition. Heat treatment conditions were optimized so that the atoms diffused out along the grain boundaries to form nanocrystals at the catalyst-substrate interfaces. Graphene patterns were obtained under patterned catalysts, which restricted graphene formation to within patterned areas. The resultant multilayer graphene was characterized by Raman spectroscopy and transmission electron microscopy to verify the high crystallinity and two-dimensional nanomorphology. Finally, a metal-semiconductor diode with a catalyst-graphene contact structure were fabricated and characterized to assess the semiconducting properties of the graphene sheets with respect to the display of asymmetric current-voltage behavior. PMID:22709270

  20. Direct chemical conversion of graphene to boron- and nitrogen- and carbon-containing atomic layers

    Gong, Yongji; Shi, Gang; Zhang, Zhuhua; Zhou, Wu; Jung, Jeil; Gao, Weilu; Ma, Lulu; Yang, Yang; Yang, Shubin; You, Ge; Vajtai, Robert; Xu, Qianfan; MacDonald, Allan H.; Yakobson, Boris I.; Lou, Jun; Liu, Zheng; Ajayan, Pulickel M.

    2014-01-01

    Graphene and hexagonal boron nitride are typical conductor and insulator, respectively, while their hybrids hexagonal boron carbonitride are promising as a semiconductor. Here we demonstrate a direct chemical conversion reaction, which systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride structures without disrupting the structural integrity of the original graphene templates. We synthesize high-quality atomic layer films with boron-, nitrogen- and carbon-containing atomic layers with full range of compositions. Using this approach, the electrical resistance, carrier mobilities and bandgaps of these atomic layers can be tuned from conductor to semiconductor to insulator. Combining this technique with lithography, local conversion could be realized at the nanometre scale, enabling the fabrication of in-plane atomic layer structures consisting of graphene, boron nitride and boron carbonitride. This is a step towards scalable synthesis of atomically thin two-dimensional integrated circuits.

  1. Electric Characteristics of the Carbon Nanotube Network Transistor with Directly Grown ZnO Nanoparticles.

    Kim, Un Jeong; Bae, Gi Yoon; Suh, Dong Ik; Park, Wanjun

    2016-03-01

    We report on the electrical characteristics of field effect transistors fabricated with random networks of single-walled carbon nanotubes with surfaces modified by ZnO nanoparticles. ZnO nanoparticles are directly grown on single-walled carbon nanotubes by atomic layer deposition using diethylzinc (DEZ) and water. Electrical observations show that ZnO nanoparticles act as charge transfer sources that provide electrons to the nanotube channel. The valley position in ambipolar transport of nanotube transistors is negatively shifted for 3V due to the electronic n-typed property of ZnO nanoparticles. However, the Raman resonance remains invariant despite the charge transfer effect produced by ZnO nanoparticles. PMID:27455727

  2. Flexible carbon micro-supercapacitors prepared by direct cw-laser writing

    Cai, Jinguang; Watanabe, Akira

    2016-03-01

    Micro-/nano-scale power supply units with high energy and high power densities are critical components for the development of compact miniaturized portable electronic devices. Supercapacitors have attracted many research attentions due to their high power density, robust cycle performance, pollution-free operation, and maintenance-free features. Besides, the properties of small size, light weight, and flexibility are also required. On-chip microsupercapacitors (MSCs) have the potential acting as power supply units in portable devices, due to their simplified packaging processes and compatibility to the integrated circuits. However, the fabrication methods and materials should be cost-effective, scalable, and compatible to current electronic industry. Carbon materials own high specific surface areas, electrochemical stability, and high electrical conductivity, which are critical parameters for high-power supercapacitors. Moreover, the high mechanical tolerance makes them good candidates for flexible wearable devices. Therefore, MSCs based on carbon materials would satisfy the requirements of portable electronics. In this work, we demonstrated the fabrication of carbon MSCs by laser direct writing on commercial polyimide sheets in Ar with lowcost semiconductor cw-laser with a wavelength of 405nm. The obtained structures are macro-nanostructures comprising graphitized and amorphous carbon with relatively smooth surfaces and low resistance, in compared with the structures obtained by laser writing in air. As-prepared micro-supercapacitors show a high capacitance of about 14.9 mF/cm2 at a scanning rate of 10 mV/s, which is comparable to the reported highest capacitance of carbon-based supercapacitors fabricated by pulse-laser writing.

  3. A 2MW 6-phase BLDC Generator Developed from a PM Synchronous Generator for Wind Energy Application

    Chen, Zhuihui; Chen, Zhe; Liu, Xiao

    In the direct drive wind turbine application, a PMSM generator often works together with a diode rectifier, which connects to a boost converter. In this paper, a six-phase BLDC generator is developed from the prototype design of three-phase permanent magnet synchronous generator. The diode rectif...

  4. Investigation of the potential of Pb/Pb radiometric dating for the direct age determination of carbonates

    Russell, Jonathan; Moorbath, S.; Whitehouse, Martin; Prof. Stephen Moorbath; Dr. Paul Taylor; Dr. Martin Whitehouse

    1992-01-01

    Recent studies have demonstrated the potentially robust nature of U-Pb and Pb/Pb systematics within certain sedimentary and metamorphic carbonates (e.g. Moorbath et al., 1987; Jahn, 1988; Jahn et al., 1990; DeWolf and Halliday, 1991). During the course of this work, the Pb/Pb dating technique has been applied successfully to the direct dating of Proterozoic stromatolitic carbonates from Western Australia and India, Silurian stromatoporoidal carbonates from Sweden and Archae...

  5. Effect of Direct Seeding Mulch-Based Systems on Soil Carbon Storage and Macrofauna in Central Brazil

    Eric Blanchart; Martial Bernoux; Xavier Sarda; Marcos Siqueira Neto; Carlos C. Cerri; Marisa Piccolo; Jean-marie Douzet; Eric Scopel; Christian Feller

    2007-01-01

    Soils represent a large carbon pool, approximately 1500 Gt, equivalent to almost three times the quantity stored in terrestrial biomass and twice the amount stored in the atmosphere. Any modification of land-use or land management can induce variations in soil carbon stocks, even in agricultural systems that are perceived to be in a steady state. These modifications also alter soil macrofauna that is known to affect soil carbon dynamics. Direct seeding Mulch-based Cropping (DMC) systems with ...

  6. Direct Synthesis of Phenol from Benzene on an Activated Carbon Catalyst Treated with Nitric Acid

    Cui-hong Chen; Jia-quan Xu; Ming-ming Jin; Gui-ying Li; Chang-wei Hu

    2011-01-01

    Commercially available coal-based activated carbon was treated by nitric acid with different concentrations and the resultant samples were used as catalysts for the direct hydroxylation of benzene to phenol in acetonitrile. Boehm titration, X-ray photoelectron spectroscopy,scanning electron microscope coupled with an energy dispersive X-ray microanalyzer, and Brunauer-Emmett-Teller method were used to characterize toe samples. The number of carboxyl groups on the surface was found to be the main factor affecting the catalytic activity. An optimum catalytic performance with a yield of 15.7% and a selectivity of 87.2% to phenol was obtained.

  7. Direct measurement of the oceanic carbon monoxide flux by eddy correlation

    B. W. Blomquist; C. W. Fairall; Huebert, B. J.; S. T. Wilson

    2012-01-01

    This report presents results from a field trial of ship-based air–sea flux measurements of carbon monoxide (CO) by direct eddy correlation with an infrared-laser trace gas analyzer. The analyzer utilizes Off-Axis Integrated-Cavity-Output Spectroscopy (OA-ICOS) to achieve high selectivity for CO, rapid response (~2 Hz) and low noise. Over a two-day sea trial, peak daytime seawater CO concentrations were ~1.5 nM and wind speeds were consistently 10–12 m s−1. A clear diel ...

  8. A carbon dioxide partial condensation direct cycle for advanced gas cooled fast and thermal reactors

    A carbon dioxide partial condensation direct cycle concept has been proposed for gas cooled fast and thermal reactors. The fast reactor with the concept are evaluated to be a potential alternative option to liquid metal cooled fast reactors, providing comparable cycle efficiency at the same core outlet temperature, eliminating the safety problems, simplifying the heat transport system and making easier plant maintenance. The thermal reactor with the concept is expected to be an alternative solution to current high temperature gas cooled reactors (HTGRs) with helium gas turbines, allowing comparable cycle efficiency at the moderate temperature of 650 C instead of 800 C in HTGRs. (author)

  9. A direct evidence for high carbon dioxide and radon-222 discharge in Central Nepal

    Perrier, F.; Byrdina, S. [Inst Phys Globe, UMR 7154, Equipe Geomagnetisme, F-75005 Paris (France); Univ Paris Diderot, F-75005 Paris (France); Richon, P.; Bollinger, L.; Bureau, S. [CEA Bruyeres le Chatel, DIF, Dept Anal Surveillance Environm, 91 (France); Richon, P. [Inst Phys Globe, UMR 7154, Equipe Geol Syst Volcan, F-75005 Paris (France); France-Lanord, Ch. [CNRS, Ctr Rech Petrog and Geochim, F-54501 Vandoeuvre Les Nancy (France); Rajaure, S.; Koirala, Bharat Prasad; Shrestha, Prithvi Lal; Gautam, Umesh Prasad; Tiwari, Dilli Ram; Sapkota, Soma Nath [Natl Seism Ctr, Dept Mines and Geol, Kathmandu (Nepal); Revil, A. [Colorado Sch Mines, Dept Geophys, Golden, CO 80401 (United States); Revil, A. [Univ Savoie, Equipe Volcans, CNRS, LGIT, UMR 5559, Chambery (France); Contraires, S. [Inst Phys Globe, Equipe Geomat and Environm, F-75005 Paris (France)

    2009-02-15

    Gas discharges have been identified at the Syabru-Bensi hot springs, located at the front of the High Himalaya in Central Nepal, in the Main Central Thrust zone. The hot spring waters are characterized by a temperature reaching 61 C, high salinity, high alkalinity and {delta}{sup 13}C varying from +0. 7 parts per thousand to +4. 8 parts per thousand. The gas is mainly dry carbon dioxide, with a {delta}{sup 13}C of -0. 8 parts per thousand. The diffuse carbon dioxide flux, mapped by the accumulation chamber method, reached a value of 19000 g m{sup -2}day{sup -1}, which is comparable with values measured on active volcanoes. Similar values have been observed over a two-year time interval and the integral around the main gas discharge amounts to 0. 25 {+-} 0. 07 mol s{sup -1}, or 350 {+-} 100 ton a{sup -1}. The mean radon-222 concentration in spring water did not exceed 2. 5 Bq L{sup -1}, exponentially decreasing with water temperature. In contrast, in gas bubbles collected in the water or in the dry gas discharges, the radon concentration varied from 16 000 to 41000 Bq m{sup -3}. In the soil, radon concentration varied from 25000 to more than 50000 Bq m{sup -3}. Radon flux, measured at more than fifty points, reached extreme values, larger than 2 Bq m{sup -2}s{sup -1}, correlated to the larger values of the carbon dioxide flux. Our direct observation confirms previous studies which indicated large degassing in the Himalaya. The proposed understanding is that carbon dioxide is released at mid-crustal depth by metamorphic reactions within the Indian basement, transported along pre-existing faults by meteoric hot water circulation, and degassed before reaching surface. This work, first, confirms that further studies should be undertaken to better constrain the carbon budget of the Himalaya, and, more generally, the contribution of mountain building to the global carbon balance. Furthermore, the evidenced gas discharges provide a unique natural laboratory for

  10. Combined Power Generation and Carbon Sequestration Using Direct FuelCell

    Hossein Ghezel-Ayagh

    2006-03-01

    The unique chemistry of carbonate fuel cell offers an innovative approach for separation of carbon dioxide from greenhouse gases (GHG). The carbonate fuel cell system also produces electric power at high efficiency. The simultaneous generation of power and sequestration of greenhouse gases offer an attractive scenario for re-powering the existing coal-fueled power plants, in which the carbonate fuel cell would separate the carbon dioxide from the flue gas and would generate additional pollutant-free electric power. Development of this system is concurrent with emergence of Direct FuelCell{reg_sign} (DFC{reg_sign}) technology for generation of electric power from fossil fuels. DFC is based on carbonate fuel cell featuring internal reforming. This technology has been deployed in MW-scale power plants and is readily available as a manufactured product. This final report describes the results of the conceptualization study conducted to assess the DFC-based system concept for separation of CO2 from GHG. Design and development studies were focused on integration of the DFC systems with coal-based power plants, which emit large amounts of GHG. In parallel to the system design and simulation activities, operation of laboratory scale DFC verified the technical concept and provided input to the design activity. The system was studied to determine its effectiveness in capturing more than ninety percent of CO2 from the flue gases. Cost analysis was performed to estimate the change in cost of electricity for a 200 MW pulverized coal boiler steam cycle plant retrofitted with the DFC-based CO2 separation system producing an additional 127 MW of electric power. The cost increments as percentage of levelized cost of electricity were estimated for a range of separation plant installations per year and a range of natural gas cost. The parametric envelope meeting the goal (<20% increase in COE) was identified. Results of this feasibility study indicated that DFC-based separation

  11. High power direct methanol fuel cell with a porous carbon nanofiber anode layer

    Highlights: • This study demonstrates a novel porous carbon nanofiber anode (PNCF) layer. • PNFC anode layer DMFC presents power density of 23.0 mW cm−2. • This unit operates at room temperature and consumes low concentration of methanol. - Abstract: Three anode electrodes containing Pt–Ru Black as a catalyst were fabricated with a porous layer made with different carbon materials: carbon black (CB), carbon nanofiber (CNF) and a combination of both carbon materials (CB + CNF). The carbon-based porous layer was coated onto a carbon cloth with PTFE pre-treatment for delivering hydrophobic properties and applied in direct methanol fuel cells (DMFCs). Characterisation of electrochemical properties for three different anode electrodes was performed with cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) at room temperature in a half-cell configuration. The evolution of the surface morphology of diffusion layer and electrodes was characterised by using variable-pressure scanning electron microscopy (VP-SEM). The electrochemical results indicate that electrode with CNF layer showed the highest current densities compared to CB and CB + CNF with the same catalyst loading. VP-SEM measurements show the network formation within the structure, which could facilitate the methanol mass transfer and improve the catalyst efficiency. The electrodes were applied to a single-cell DMFC, and the cell performance was experimentally investigated under passive operating mode and room temperature. A maximum power density of 23.0 mW cm−2 at a current density of 88.0 mA cm−2 with a 3 M dilute methanol solution was achieved. The results show that the electrodes with a CNF layer could improve the performance of DMFC as compared with commercially used CB and prove it’s potentially application in DMFC technology especially for portable power source applications due to several advantages as followings: operating at low concentration of

  12. A direct evidence for high carbon dioxide and radon-222 discharge in Central Nepal

    Gas discharges have been identified at the Syabru-Bensi hot springs, located at the front of the High Himalaya in Central Nepal, in the Main Central Thrust zone. The hot spring waters are characterized by a temperature reaching 61 C, high salinity, high alkalinity and δ13C varying from +0. 7 parts per thousand to +4. 8 parts per thousand. The gas is mainly dry carbon dioxide, with a δ13C of -0. 8 parts per thousand. The diffuse carbon dioxide flux, mapped by the accumulation chamber method, reached a value of 19000 g m-2day-1, which is comparable with values measured on active volcanoes. Similar values have been observed over a two-year time interval and the integral around the main gas discharge amounts to 0. 25 ± 0. 07 mol s-1, or 350 ± 100 ton a-1. The mean radon-222 concentration in spring water did not exceed 2. 5 Bq L-1, exponentially decreasing with water temperature. In contrast, in gas bubbles collected in the water or in the dry gas discharges, the radon concentration varied from 16 000 to 41000 Bq m-3. In the soil, radon concentration varied from 25000 to more than 50000 Bq m-3. Radon flux, measured at more than fifty points, reached extreme values, larger than 2 Bq m-2s-1, correlated to the larger values of the carbon dioxide flux. Our direct observation confirms previous studies which indicated large degassing in the Himalaya. The proposed understanding is that carbon dioxide is released at mid-crustal depth by metamorphic reactions within the Indian basement, transported along pre-existing faults by meteoric hot water circulation, and degassed before reaching surface. This work, first, confirms that further studies should be undertaken to better constrain the carbon budget of the Himalaya, and, more generally, the contribution of mountain building to the global carbon balance. Furthermore, the evidenced gas discharges provide a unique natural laboratory for methodological studies, and appear particularly important to study as a function of time

  13. Direct prediction of the desalination performance of porous carbon electrodes for capacitive deionization

    Porada, S.; Borchardt, D.; Oschatz, M.; Bryjak, M.; Atchison, J.S.; Keesman, K.J.; Kaskel, S.; Biesheuvel, P.M.; Presser, V.

    2013-01-01

    Desalination by capacitive deionization (CDI) is an emerging technology for the energy- and cost-efficient removal of ions from water by electrosorption in charged porous carbon electrodes. A variety of carbon materials, including activated carbons, templated carbons, carbon aerogels, and carbon nan

  14. Carbon nanotubes supported Cu-Ni bimetallic catalysts and their properties for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide

    Multi-walled carbon nanotubes (MWCNTs) supported Cu-Ni bimetallic catalysts for the direct synthesis of dimethyl carbonate (DMC) from CH3OH and CO2 were synthesized and investigated. The supporting materials and the synthesized catalysts were fully characterized using FTIR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS) techniques. The catalytic activities were investigated by performing micro-reactions. The experimental results showed that the metal phase and Cu-Ni alloy phase in the catalyst were partially formed during the calcination and activation step. Active metal particles were dispersed homogeneously on the surface of the MWCNTs. Cu-Ni/MWCNTs catalysts were efficient for the direct synthesis of DMC. The highest conversion of CH3OH was higher than 4.3% and the selectivity of DMC was higher than 85.0% under the optimal catalytic conditions of 120 deg. C and around 1.2 MPa. The high catalytic activity of Cu-Ni/MWCNTs in DMC synthesis can be attributed to the synergetic effects of metal Cu, Ni and Cu-Ni alloy in the activation of CH3OH and CO2, the unique structure of MWCNTs and the interaction between the metal particles and the supports.

  15. Carbon out-diffusion mechanism for direct graphene growth on a silicon surface

    Direct growth of graphene on silicon (Si) through chemical vapor deposition has predominantly focused on surface-mediated processes due to the low carbon (C) solubility in Si. However, a considerable quantity of C atoms was incorporated in Si and formed Si1−xCx alloy with a reduced lattice dimension even in the initial stage of direct graphene growth. Subsequent high temperature annealing promoted active C out-diffusion, resulting in the formation of a graphitic layer on the Si surface. Furthermore, the significantly low thermal conductivity of the Si1−xCx alloy shows that the incorporated C atoms affect the properties of a semiconductor adjacent to the graphene. These findings provide a key guideline for controlling desirable properties of graphene and designing hybrid semiconductor/graphene architectures for various applications

  16. Porous Diatomite-Immobilized Cu–Ni Bimetallic Nanocatalysts for Direct Synthesis of Dimethyl Carbonate

    Yong Chen

    2012-01-01

    Full Text Available A series of diatomite-immobilized Cu–Ni bimetallic nanocatalysts was prepared under ultrasonication and evaluated for the direct synthesis of dimethyl carbonate under various conditions. Upon being fully characterized by TPR, TPD, BET, SEM, XRD, and XPS methodologies, it is found that the bimetallic composite is effectively alloyed and well immobilized inside or outside the pore of diatomite. Under the optimal conditions of 1.2 MPa and 120∘C, the prepared catalyst with loading of 15% exhibited the highest methanol conversion of 6.50% with DMC selectivity of 91.2% as well as more than 10-hour lifetime. The possible reaction mechanism was proposed and discussed in detail. To our knowledge, this is the first report to use diatomite as a catalyst support for direct DMC synthesis from methanol and CO2.

  17. Scattering directionality parameters of fractal black carbon aerosols and comparison with the Henyey-Greenstein approximation.

    Pandey, Apoorva; Chakrabarty, Rajan K

    2016-07-15

    Current radiation transfer schemes employ the Henyey-Greenstein (HG) phase function to connect three single parameter representations of aerosol scattering directionality-the hemispherical upscatter fraction (β), the backscatter fraction (b), and the asymmetry parameter (g). The HG phase function does not account for particle morphology, which could lead to significant errors. In this Letter, we compute these single parameters for fractal black carbon (BC) aerosols using the numerically exact superposition T-matrix method. The variations in β, g, and b as a function of aerosol morphology are examined. Corrected empirical relationships connecting these parameters are proposed. We find that the HG phase function could introduce up to a 35% error in β and g estimates. Interestingly, these errors are suppressed by the large mass absorption cross-sections of BC aerosols in radiative transfer calculations and contribute to ≤8% error in direct forcing efficiencies. PMID:27420533

  18. Direct growth of graphene on gallium nitride using C2H2 as carbon source

    Wang, Bing; Zhao, Yun; Yi, Xiao-Yan; Wang, Guo-Hong; Liu, Zhi-Qiang; Duan, Rui-Rei; Huang, Peng; Wang, Jun-Xi; Li, Jin-Min

    2016-04-01

    Growing graphene on gallium nitride (GaN) at temperatures greater than 900°C is a challenge that must be overcome to obtain high quality of GaN epi-layers. We successfully met this challenge using C2H2 as the carbon source. We demonstrated that graphene can be grown both on copper and directly on GaN epi-layers. The Raman spectra indicated that the graphene films were about 4-5 layers thick. Meanwhile, the effects of the growth temperature on the growth of the graphene films were systematically studied, and 830°C was found to be the optimum growth temperature. We successfully grew high-quality graphene films directly on gallium nitride.

  19. Carbon nanotube network film directly grown on carbon cloth for high-performance solid-state flexible supercapacitors

    Carbon nanotubes (CNTs) have received increasing attention as electrode materials for high-performance supercapacitors. We herein present a straightforward method to synthesize CNT films directly on carbon cloths as electrodes for all-solid-state flexible supercapacitors (AFSCs). The as-made highly conductive electrodes possess a three-dimensional (3D) network architecture for fast ion diffusion and good flexibility, leading to an AFSC with a specific capacitance of 106.1 F g−1, an areal capacitance of 38.75 mF cm−2, an ultralong cycle life of 100 000 times (capacitance retention: 99%), a good rate capability (can scan at 1000 mV s−1, at which the capacitance is still ∼37.8% of that at 5 mV s−1), a high energy density (2.4 μW h cm−2) and a high power density (19 mW cm−2). Moreover, our AFSC maintains excellent electrochemical attributes even with serious shape deformation (bending, folding, etc), high mechanical pressure (63 kPa) and a wide temperature window (up to 100 ° C). After charging for only 5 s, three such AFSC devices connected in series can efficiently power a red round LED for 60 s. Our work could pave the way for the design of practical AFSCs, which are expected to be used for various flexible portable/wearable electronic devices in the future. (paper)

  20. Carbon-Supported PtRuMo Electrocatalysts for Direct Alcohol Fuel Cells

    José L.G. Fierro

    2013-10-01

    Full Text Available The review article discusses the current status and recent findings of our investigations on the synthesis and characterization of carbon-supported PtRuMo electrocatalysts for direct alcohol fuel cells. In particular, the effect of the carbon support and the composition on the structure, stability and the activity of the PtRuMo nanoparticles for the electrooxidation of CO, methanol and ethanol have been studied. Different physicochemical techniques have been employed for the analysis of the catalysts structures: X-ray analytical methods (XRD, XPS, TXRF, thermogravimetry (TGA and transmission electron microscopy (TEM, as well as a number of electrochemical techniques like CO adsorption studies, current-time curves and cyclic voltammetry measurements. Furthermore, spectroscopic methods adapted to the electrochemical systems for in situ studies, such as Fourier transform infrared spectroscopy (FTIRS and differential electrochemical mass spectrometry (DEMS, have been used to evaluate the oxidation process of CO, methanol and ethanol over the carbon-supported PtRuMo electrocatalysts.

  1. Direct mineral carbonation of steelmaking slag for CO2 sequestration at room temperature.

    Rushendra Revathy, T D; Palanivelu, K; Ramachandran, A

    2016-04-01

    Rapid increase of CO2 concentration in the atmosphere has forced the international community towards adopting actions to restrain from the impacts of climate change. Moreover, in India, the dependence on fossil fuels is projected to increase in the future, implying the necessity of capturing CO2 in a safe manner. Alkaline solid wastes can be utilized for CO2 sequestration by which its disposal issues in the country could also be met. The present work focuses to study direct mineral carbonation of steelmaking slag (SS) at room temperature and low-pressure conditions (carbonation of SS was carried out in a batch reactor with pure CO2 gas. The process parameters that may influence the carbonation of SS, namely, CO2 gas pressure, liquid to solid ratio (L/S) and reaction time were also studied. The results showed that maximum sequestration of SS was attained in the aqueous route with a capacity of 82 g of CO2/kg (6 bar, L/S ratio of 10 and 3 h). In the gas-solid route, maximum sequestration capacity of about 11.1 g of CO2/kg of SS (3 bar and 3 h) was achieved indicating that aqueous route is the better one under the conditions studied. These findings demonstrate that SS is a promising resource and this approach could be further developed and used for CO2 sequestration in the country. The carbonation process was evidenced using FT-IR, XRD, SEM and TG analysis. PMID:26681331

  2. Study of removal of Direct Yellow 12 by cadmium oxide nanowires loaded on activated carbon

    Ghaedi, Mehrorang, E-mail: m_ghaedi@mail.yu.ac.ir [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Sadeghian, Batuol [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Kokhdan, Syamak Nasiri, E-mail: syamak.nasiri@yahoo.com [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Pebdani, Arezou Amiri [Chemistry Department, Yasouj University Yasouj 75914-35 (Iran, Islamic Republic of); Sahraei, Reza; Daneshfar, Ali; Mihandoost, Asma [Department of Chemistry, University of Ilam, P.O. Box: 65315-516, Ilam (Iran, Islamic Republic of)

    2013-05-01

    In this research, cadmium oxide nanowires loaded on activated carbon (CdO-NW-AC) has been synthesized by a simple procedure and characterized by different techniques such as XRD, SEM and UV–vis spectrometry. This new adsorbent has been efficiently utilized for the removal of the Direct Yellow 12 (DY-12) from wastewater. To obtain maximum DY-12 removal efficiency, the influences of variables such as pH, DY-12 concentration, amount of CdO-NW-AC, contact time, and temperature have been examined and optimized in a batch method. Following the variable optimization, the experimental equilibrium data (at different concentration of DY-12) was fitted to conventional isotherm models such as Langmuir, Freundlich and Tempkin. The applicability of each method is based on the R{sup 2} and error analysis for each model. It was found that the experimental equilibrium data well fitted to the Langmuir isotherm model. The dependency of removal process to time and the experimental data follow second order kinetic model with involvement of intraparticle diffusion model. The negative value of Gibbs's free energy and positive value of adsorption enthalpy show the spontaneous and endothermic nature of adsorption process. - Graphical abstract: Typical FE-SEM image of the CdO nanowires. Highlights: ► Cadmium oxide nanowires loaded on activated carbon was utilized as an adsorbent. ► It was used for the removal of Direct Yellow 12 from aqueous solutions. ► The adsorption of Direct Yellow 12 on this adsorbent is endothermic in nature. ► The adsorption equilibrium data was well described by the Langmuir isotherm model.

  3. Klystron Linearizer for Use with 1.2 MW 476 MHz Klystrons in PEP-II RF Systems

    Fox, John; Mastorides, Themis; Teytelman, Dmitry; Van Winkle, Daniel; Zhou, Yubo

    2005-01-01

    The direct and comb loop feedback around the RF cavities in PEP-II is critical in reducing longitudinal instabilities driven by the cavity impedance, and the non-linear 1 MW klystron is in the signal path for these feedback loops. As a result, the effective small-signal gain of the klystron at 85% saturation reduces the impedance control by factors of 5 to 20 as compared to a linear power amplifier. A klystron linearizer circuit has been developed which operates in series with the power amplifier and acts to equalize the small and large signal gains through the combination. The technique must implement a 1 MHz linear control bandwidth over roughly 15 dB of RF signal level variation. The dynamics of this system is operating point dependent, and the channel must have dynamic gain compensation to keep the linearity compensation loop stable over changes in operating point. The design of this non-linear signal processing channel (incorporating RF and DSP techniques) and measured results from full-power klystron te...

  4. Application of TEMPPC code to the IEA-R1 nuclear reactor core hydrothermal calculations operating at 2 MW for determining the minimal coolant flow

    A thermohydraulic study of the IEA-R1 nuclear reactor core on steady-state operating condition and forced convection, is presented. The objective of this calculation is to obtain the minimal flow rate of coolant necessary at the reactor core, limited by the temperature associated to the beginning of nucleate boiling over the fuel plates at a normal operating power (2MW) for a certain inlet coolant temperature. The coolant system safety level is also calculated in this paper, which is divided in three steps: thermohydraulic calculation, without using the uncertainty factors and, after that, considering these factor by two methods: the statistical and the conventional ones. Whichever the method accepted, the results obtained by the program TEMPPC show a great safety margin with respect to the termohydraulic parameters from the IEA-R1 nuclear reactor. (Author)

  5. Benchmark analysis of the 2MW TRIGA MARK II Moroccan research reactor using the MCNP code and the latest nuclear data libraries

    This study deals with the neutronic analysis of the 2MW TRIGA MARK II Moroccan research reactor. The reactor was commissioned at Centre des Etudes Nucleaires de la Maamora (CENM) and it went critical on May 2, 2007. The 3-D continuous energy Monte Carlo code MCNP5 was used to develop a full model of the TRIGA reactor, using the maximum details allowed by the constructor General Atomics of USA. Continuous energy cross section data from the more recent nuclear data evaluations (ENDF/B-VI.8, ENDF/B-VII.0, JEFF-3.1, and JENDL-3.3) as well as S(α, β) thermal neutron scattering functions distributed with the MCNP code were used. The cross section libraries were generated by using the NJOY99 system updated to its more recent patch file 'up259'. The consistency and accuracy of both Monte Carlo simulation and neutron transport physics were established by benchmarking the TRIGA experiments. (author)

  6. Direct Observation of a Carbon Filament in Water-Resistant Organic Memory.

    Lee, Byung-Hyun; Bae, Hagyoul; Seong, Hyejeong; Lee, Dong-Il; Park, Hongkeun; Choi, Young Joo; Im, Sung-Gap; Kim, Sang Ouk; Choi, Yang-Kyu

    2015-07-28

    The memory for the Internet of Things (IoT) requires versatile characteristics such as flexibility, wearability, and stability in outdoor environments. Resistive random access memory (RRAM) to harness a simple structure and organic material with good flexibility can be an attractive candidate for IoT memory. However, its solution-oriented process and unclear switching mechanism are critical problems. Here we demonstrate iCVD polymer-intercalated RRAM (i-RRAM). i-RRAM exhibits robust flexibility and versatile wearability on any substrate. Stable operation of i-RRAM, even in water, is demonstrated, which is the first experimental presentation of water-resistant organic memory without any waterproof protection package. Moreover, the direct observation of a carbon filament is also reported for the first time using transmission electron microscopy, which puts an end to the controversy surrounding the switching mechanism. Therefore, reproducibility is feasible through comprehensive modeling. Furthermore, a carbon filament is superior to a metal filament in terms of the design window and selection of the electrode material. These results suggest an alternative to solve the critical issues of organic RRAM and an optimized memory type suitable for the IoT era. PMID:26056735

  7. Direct synthesis of dimethyl carbonate over rare earth oxide supported catalyst

    JIANG Qi; CHENG Jiye; GAO Zhiqin

    2007-01-01

    Solid base catalysts for the direct synthesis of dimethyl carbonate (DMC)from carbon dioxide,methanol,and propylene oxide were prepared by loading KCl and K2CO3 on the surface of La2O3,Y2O31,CeO2 and Nd2O3.The catalysts were characterized by thermogravimetric analysis (TGA) and X-ray diffraction(XRD) techniques.The catalytic activities were efficiently influenced by the preparation conditions.The optimal loading amount of K2CO3 is 17.6%(mass)for KCl-K2CO3/Y2O3 and 22.2%for other catalysts.Supports affected the activity of catalyst.KCl-K2CO3/Nd2O3 exhibited the highest activity.The activity of KCl-K2CO3/Y2O3 increased wilh the increase of Calcination temperature in the range of 800℃-900℃.The formation of KYO2 Y3O4Cl or YOx species probably promoted the catalysts.

  8. Cathode catalyst layer using supported Pt catalyst on ordered mesoporous carbon for direct methanol fuel cell

    Kim, Hee-Tak; Yoon, Hae-Kwon; Song, In-Seob [Samsung SDI Co. Ltd., 575 Shin-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-391 (Korea); You, Dae Jong; Joo, Sang Hoon; Pak, Chanho; Chang, Hyuk [Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600 (Korea)

    2008-06-01

    The development of a cathode catalyst layer based on a supported Pt catalyst using an ordered mesoporous carbon (OMC) for direct methanol fuel cell is reported. An OMC with a mesopore structure between hexagonally arranged carbon nanorods is prepared using a template method. Platinum nanoparticles are supported on the OMC (Pt/OMC) with high metal loading of 60 wt.%. Compositional and morphological variations are made by varying the ionomer content and by compressing the catalyst layer to detect a parameter that determines the power performance. Increase in power density with decrease in the volume fraction of ionomer in the agglomerate comprising the Pt/OMC and the ionomer indicates that mass transport through the ionomer phase governs the kinetics of oxygen reduction. Impedance spectroscopic analysis suggests that a significant mass-transport limitation occurs at high ionomer content and in the compressed cathode. The power density of the optimum cathode layer, which employs a Pt/OMC catalyst with a Pt loading of 2 mg cm{sup -2}, is greater than that of a catalyst layer with 6 mg cm{sup -2} Pt-black catalyst at a voltage higher than 0.4 V. This would lead to a significant reduction in the cost of the membrane electrode assembly. (author)

  9. Direct laser interference patterning of multi-walled carbon nanotube-based transparent conductive coatings

    Topographical structures were created on the surface of multi-walled carbon nanotube-based coatings deposited on borosilicate glass using the direct laser interference patterning (DLIP) technique. Films made by multi-walled carbon nanotubes (MWNTs) dispersed in antimony-doped tin oxide (ATO) matrix and networks of MWNTs with both low and high adherence to the substrates were irradiated with one single laser pulse. Due to the high absorption coefficient of ATO, the film was completely removed at the interference maxima positions leading to periodic arrays of high quality on macroscopic areas. Additionally, increase of the laser fluence has produced wider ablated regions. Irradiation of high adherent networks of MWNTs produced a periodic porous structure, what has been attributed to the presence of adherence promoters in the film. On the other hand, MWNT networks with low adhesion to the substrate were strongly removed at the interference maxima positions. In this case, however, the fabricated periodic structures presented several defects that result from the poor adherence of the film to the substrate

  10. Effect of reactor temperature on direct growth of carbon nanomaterials on stainless steel

    Edzatty, A. N.; Syazwan, S. M.; Norzilah, A. H.; Jamaludin, S. B.

    2016-07-01

    Currently, carbon nanomaterials (CNMs) are widely used for various applications due to their extraordinary electrical, thermal and mechanical properties. In this work, CNMs were directly grown on the stainless steel (SS316) via chemical vapor deposition (CVD). Acetone was used as a carbon source and argon was used as carrier gas, to transport the acetone vapor into the reactor when the reaction occurred. Different reactor temperature such as 700, 750, 800, 850 and 900 °C were used to study their effect on CNMs growth. The growth time and argon flow rate were fixed at 30 minutes and 200 ml/min, respectively. Characterization of the morphology of the SS316 surface after CNMs growth using Scanning Electron Microscopy (SEM) showed that the diameter of grown-CNMs increased with the reactor temperature. Energy Dispersive X-ray (EDX) was used to analyze the chemical composition of the SS316 before and after CNMs growth, where the results showed that reduction of catalyst elements such as iron (Fe) and nickel (Ni) at high temperature (700 - 900 °C). Atomic Force Microscopy (AFM) analysis showed that the nano-sized hills were in the range from 21 to 80 nm. The best reactor temperature to produce CNMs was at 800 °C.

  11. Fluorescent carbon quantum dot hydrogels for direct determination of silver ions.

    Cayuela, A; Soriano, M L; Kennedy, S R; Steed, J W; Valcárcel, M

    2016-05-01

    The paper reports for the first time the direct determination of silver ion (Ag(+)) using luminescent Carbon Quantum Dot hydrogels (CQDGs). Carbon Quantum Dots (CQDs) with different superficial moieties (passivate-CQDs with carboxylic groups, thiol-CQDs and amine-CQDs) were used to prepare hybrid gels using a low molecular weight hydrogelator (LMWG). The use of the gels results in considerable fluorescence enhancement and also markedly influences selectivity. The most selective CQDG system for Ag(+) ion detection proved to be those containing carboxylic groups onto their surface. The selectivity towards Ag(+) ions is possibly due to its flexible coordination sphere compared with other metal ions. This fluorescent sensing platform is based on the strong Ag-O interaction which can quench the photoluminescence of passivate-CQDs (p-CQDs) through charge transfer. The limit of detection (LOD) and quantification (LOQ) of the proposed method were 0.55 and 1.83µgmL(-1), respectively, being applied in river water samples. PMID:26946015

  12. Directly obtaining high strength silk fiber from silkworm by feeding carbon nanotubes

    By feeding silkworm with the carbon nanotube, CNT, we directly obtained high strength silk fiber, SF, from silkworm. The CNT-based SF, SF/CNT, has a stress at 1.69 GPa and a strain at about 24% both higher than those of the SF and are capable to compare with the super SF and even the spider fiber. Morphology comparison showed that the presence of CNT in SF caused the cross-section changed from triangle to ellipse. X-ray diffraction and infrared analysis indicated that the embedded CNT in SF caused an increase in silk-I structure. Specifically the amide-II structure reduced by about 5% and the amide-III structure increased by about 10%. Thermogravimetric analyses indicated that the presence of CNT in SF enhanced the thermal stability. Additionally, the presence of CNT in SF also enhanced the electrical property. - Highlights: • Pristine silk fibers in vivo reinforced by feeding carbon nanotubes to silkworms • Embedding CNTs into SFs improved the mechanical, thermal and electrical properties. • Embedding CNTs into SFs reduced amide II and increased amide III

  13. Low-density carbonized composite foams for direct-drive laser ICF targets

    The design for a direct-drive, high-gain laser inertial confinement fusion target calls for the use of a low-density, low-atomic-number foam to confine and stabilize liquid deuterium-tritium (DT) in a spherical-shell configuration. Over the past two years, we have successfully developed polystyrene foams (PS) and carbonized resorcinol-formaldehyde foams (CRF) for that purpose. Both candidates are promising materials with unique characteristics. PS has superior mechanical strength and machinability, but its relatively large thermal contraction is a significant disadvantage. CRF has outstanding wettability and dimensional stability in liquid DT; yet it is much more fragile than PS. To combine the strengths of both materials, we have recently developed a polymer composite foam which exceeds PS in mechanical strength, but retains the wettability and dimension stability of CRF. This paper will discuss the preparation, structure, and properties of the polymer composite foams. 5 refs., 1 fig., 1 tab

  14. Preparation of poly(propylene carbonate)/organophilic rectorite nanocomposites via direct melt intercalation

    WAN Chun-jie; YU Jian-ying; SHI Xiao-jian; HUANG Li-hua

    2006-01-01

    The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC nanocomposites were investigated. The wide-angle X-ray diffraction (WAXD) results show that the galleries distance of OREC is increased after PPC and OREC melt intercalation,which indicates that PPC molecular chain has intercalated into the layers of OREC. The PPC/OREC nanocomposites with lower OREC content show an increase in thermal decomposition temperature compared with pure PPC. The tensile strength and impact strength of PPC/OREC nanocomposites are improved. When the mass fraction of OREC is 4%,the tensile strength and impact strength of the PPC/OREC nanocomposite increase by 22.86% and 48.58% respectively,compared with pure PPC.

  15. Direct Electrochemistry of Glucose Oxidase at a Gold Electrode Modified with Single-Wall Carbon Nanotubes

    Yuan Zhuobin

    2003-12-01

    Full Text Available The direct electrochemistry of glucose oxidase (GOD was accomplished at a gold electrode modified with single-wall carbon nanotubes (SWNTs. A pair of welldefined redox peaks was obtained for GOD with the reduction peak potential at –0.465 V and a peak potential separation of 23 mV at pH 7.0. Both FT-IR spectra and the dependence of the reduction peak current on the scan rate revealed that GOD adsorbed onto the SWNT surfaces. The redox wave corresponds to the redox center of the flavin adenine dinucleotide(FAD of the GOD adsorbate. The electron transfer rate of GOD redox reaction was greatly enhanced at the SWNT-modified electrode. The peak potential was shown to be pH dependent. Verified by spectral methods, the specific enzyme activity of GOD adsorbates at the SWNTs appears to be retained.

  16. Direct electrochemistry and electrocatalysis of myoglobin in dodecyltrimethylammonium bromide film modified carbon ceramic electrode

    Yuan Zhen Zhou; Hui Wang; She Ying Dong; An Xiang Tian; Zhi Xian He; Bin Chen

    2011-01-01

    Direct electrochemistry and electrocatalysis of myoglobin (Mb) were studied with Mb immobilized on dodecyltrimethylammonium bromide (DTAB) film modified carbon ceramic (CC) electrode. Cyclic voltammetry showed a pair of well-defined and nearly reversible redox peaks of Mb (FeⅡ/FeⅢ) at about -0.3 V vs. SCE (pH = 6.98). The currents of the redox peak were linear to scan rate, and rate constant (Ks) was estimated to be 3.03 s-1. The formal potential (E01) of Mb in the DTAB/CC electrodes shifted linearly with pH with a slope of-36.44 mV/pH, implying that the electron transfer between DTAB and CC electrodes is accompanied by proton transportation. The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide (H2O2).

  17. Measurements of electron spectra in the forward direction in slow-antiproton carbon-foil collisions

    The spectra of electrons emitted in the forward direction from antiproton and proton bombardments on carbon foils have been studied for projectile energies from 500 to 750 keV. Our main observation is that at the electron energy where the well-known convoy peak is observed for proton impact, the spectrum for equivelocity antiprotons is smooth, showing no indication of a deep anticusp. However, around 50 eV below the electron energy where the cusp is observed for proton impact, we have observed a small peak for antiproton impact. The energy and the relative intensity of the bump are found to be consistent with those predicted for electrons released from a wakeriding state. (author)

  18. A global simulation of brown carbon: implications for photochemistry and direct radiative effect

    Jo, Duseong S.; Park, Rokjin J.; Lee, Seungun; Kim, Sang-Woo; Zhang, Xiaolu

    2016-03-01

    Recent observations suggest that a certain fraction of organic carbon (OC) aerosol effectively absorbs solar radiation, which is also known as brown carbon (BrC) aerosol. Despite much observational evidence of its presence, very few global modelling studies have been conducted because of poor understanding of global BrC emissions. Here we present an explicit global simulation of BrC in a global 3-D chemical transport model (GEOS-Chem), including global BrC emission estimates from primary (3.9 ± 1.7 and 3.0 ± 1.3 TgC yr-1 from biomass burning and biofuel) and secondary (5.7 TgC yr-1 from aromatic oxidation) sources. We evaluate the model by comparing the results with observed absorption by water-soluble OC in surface air in the United States, and with single scattering albedo observations at Aerosol Robotic Network (AERONET) sites all over the globe. The model successfully reproduces the seasonal variations of observed light absorption by water-soluble OC, but underestimates the magnitudes, especially in regions with high secondary source contributions. Our global simulations show that BrC accounts for 21 % of the global mean surface OC concentration, which is typically assumed to be scattering. We find that the global direct radiative effect of BrC is nearly zero at the top of the atmosphere, and consequently decreases the direct radiative cooling effect of OC by 16 %. In addition, the BrC absorption leads to a general reduction of NO2 photolysis rates, whose maximum decreases occur in Asia up to -8 % (-17 %) on an annual (spring) mean basis. The resulting decreases of annual (spring) mean surface ozone concentrations are up to -6 % (-13 %) in Asia, indicating a non-negligible effect of BrC on photochemistry in this region.

  19. Direct Electrochemistry of Redox Proteins and Enzymes Promoted by Carbon Nanotubes

    Chenxin Cai

    2005-04-01

    Full Text Available The redox protein and enzyme, such as hemoglobin (Hb, horseradish peroxidase(HRP and glucose oxidase (GOx, was immobilized on the surface of the carbon nanotubemodified glassy carbon (CNT/GC electrode, respectively. The cyclic voltammetric resultsindicated that the redox protein and enzyme underwent effective and stable direct electrontransfer reaction with a pair of nearly symmetrical redox peaks. The formal redox potential,E0’, was almost independent on the scan rates, the average value of E0’ for Hb, HRP andGOx was –0.343 ± 0.001, –0.319 ± 0.002 and –0.456 ± 0.0008 V (vs. SCE,pH 6.9,respectively. The dependence of E0’ on the pH solution indicated that the direct electrontransfer of Hb and HRP was a one-electron-transfer reaction process coupled with oneproton-transfer, while the GOx was a two-electron-transfer coupled with two-protontransfer.The apparent heterogeneous electron transfer rate constant (ks was 1.25 ± 0.25,2.07 ± 0.69 and 1.74 ± 0.42 s-1 for Hb, HRP and GOx, respectively. The method presentedhere can be easily extended to immobilize other redox enzymes or proteins and obtain theirdirect electrochemistry.

  20. Direct Air Capture of CO2 - an Overview of Carbon Engineering's Technology and Pilot Plant Development

    Holmes, G.; Corless, A.

    2014-12-01

    At Carbon Engineering, we are developing and commercializing technology to scrub CO2 directly from atmospheric air at industrial scale. By providing atmospheric CO2 for use in fuel production, we can enable production of transportation fuels with ultra-low carbon intensities, which command price premiums in the growing set of constrained fuels markets such as California's LCFS. We are a Calgary based startup founded in 2009 with 10 employees, and we are considered a global leader in the direct air capture (DAC) field. We will review CE's DAC technology, based on a wet-scrubbing "air contactor" which absorbs CO2 into aqueous solution, and a chemical looping "regeneration" component, which liberates pure CO2 from this aqueous solution while re-making the original absorption chemical. CE's DAC tecnology exports purified atmospheric CO2, combined with the combustion CO2 from plant energy usage, as the end product. We will also discuss CE's 2014-2015 end-to-end Pilot Demonstration Unit. This is a $7M technology demonstration plant that CE is building with the help of key industrial partners and equipment vendors. Vendor design and engineering requirements have been used to specify the pilot air contactor, pellet reactor, calciner, and slaker modules, as well as auxiliary systems. These modules will be run for several months to obtain the engineering and performance data needed for subsequent commercial plant design, as well as to test the residual integration risks associated with CE's process. By the time of the AGU conference, the pilot is expected to be in late stages of fabrication or early stages of site installation.

  1. Growth of Few-Layer Graphene on Sapphire Substrates by Directly Depositing Carbon Atoms

    KANG Chao-Yang; TANG Jun; LIU Zhong-Liang; LI Li-Min; YAN Wen-Sheng; WEI Shi-Qiang; XU Peng-Shou

    2011-01-01

    Few-layer graphene (FLG) is successfully grown on sapphire substrates by directly depositing carbon atoms at the substrate temperature of 1300℃ in a molecular beam epitaxy chamber.The reflection high energy diffraction,Raman spectroscopy and near-edge x-ray absorption fine structure are used to characterize the sample,which confirm the formation of graphene layers.The mean domain size of FLG is around 29.2 nm and the layer number is about 2-3.The results demonstrate that the grown FLG displays a turbostratic stacking structure similar to that of the FLG produced by annealing C-terminated a-SiC surface.Graphene,a monolayer of sp2-bonded carbon atoms,is a quasi two-dimensional (2D) material.It has attracted great interest because of its distinctive band structure and physical properties.[1] Graphene can now be obtained by several different approaches including micromechanical[1] and chemical[2] exfoliation of graphite,epitaxial growth on hexagonal SiC substrates by Si sublimation in vacuum,[3] and CVD growth on metal substrates.[4] However,these preparation methods need special substrates,otherwise,in order to design microelectronic devices,the prepared graphene should be transferred to other appropriate substrates.Thus the growth of graphene on the suitable substrates is motivated.%Few-layer graphene (FLG) is successfully grown on sapphire substrates by directly depositing carbon atoms at the substrate temperature of 1300℃ in a molecular beam epitaxy chamber. The reflection high energy diffraction, Raman spectroscopy and near-edge x-ray absorption fine structure are used to characterize the sample, which confirm the formation of graphene layers. The mean domain size of FLG is around 29.2nm and the layer number is about 2-3. The results demonstrate that the grown FLG displays a turbostratic stacking structure similar to that of the FLG produced by annealing C-terminated α-SiC surface.

  2. Summary report : direct approaches for recycling carbon dioxide into synthetic fuel.

    Allendorf, Mark D. (Sandia National Laboratories, Livermore, CA); Ambrosini, Andrea; Diver, Richard B., Jr.; Siegel, Nathan Phillip; Miller, James Edward; Gelbard, Fred; Evans, Lindsey R.

    2009-01-01

    The consumption of petroleum by the transportation sector in the United States is roughly equivalent to petroleum imports into the country, which have totaled over 12 million barrels a day every year since 2004. This reliance on foreign oil is a strategic vulnerability for the economy and national security. Further, the effect of unmitigated CO{sub 2} releases on the global climate is a growing concern both here and abroad. Independence from problematic oil producers can be achieved to a great degree through the utilization of non-conventional hydrocarbon resources such as coal, oil-shale and tarsands. However, tapping into and converting these resources into liquid fuels exacerbates green house gas (GHG) emissions as they are carbon rich, but hydrogen deficient. Revolutionary thinking about energy and fuels must be adopted. We must recognize that hydrocarbon fuels are ideal energy carriers, but not primary energy sources. The energy stored in a chemical fuel is released for utilization by oxidation. In the case of hydrogen fuel the chemical product is water; in the case of a hydrocarbon fuel, water and carbon dioxide are produced. The hydrogen economy envisions a cycle in which H{sub 2}O is re-energized by splitting water into H{sub 2} and O{sub 2}, by electrolysis for example. We envision a hydrocarbon analogy in which both carbon dioxide and water are re-energized through the application of a persistent energy source (e.g. solar or nuclear). This is of course essentially what the process of photosynthesis accomplishes, albeit with a relatively low sunlight-to-hydrocarbon efficiency. The goal of this project then was the creation of a direct and efficient process for the solar or nuclear driven thermochemical conversion of CO{sub 2} to CO (and O{sub 2}), one of the basic building blocks of synthetic fuels. This process would potentially provide the basis for an alternate hydrocarbon economy that is carbon neutral, provides a pathway to energy independence, and is

  3. Direct soil moisture controls of future global soil carbon changes: An important source of uncertainty

    Fallon, Pete; Jones, Chris D.; Ades, Melanie; Paul, Keryn

    2011-01-01

    The nature of the climate–carbon cycle feedback depends critically on the response of soil carbon to climate, including changes in moisture. However, soil moisture–carbon feedback responses have not been investigated thoroughly. Uncertainty in the response of soil carbon to soil moisture changes could arise from uncertainty in the relationship between soil moisture and heterotrophic respiration. We used twelve soil moisture–respiration functions (SMRFs) with a soil carbon model (RothC) and da...

  4. Sequestration of flue gas CO₂ by direct gas-solid carbonation of air pollution control system residues.

    Tian, Sicong; Jiang, Jianguo

    2012-12-18

    Direct gas-solid carbonation reactions of residues from an air pollution control system (APCr) were conducted using different combinations of simulated flue gas to study the impact on CO₂ sequestration. X-ray diffraction analysis of APCr determined the existence of CaClOH, whose maximum theoretical CO₂ sequestration potential of 58.13 g CO₂/kg APCr was calculated by the reference intensity ratio method. The reaction mechanism obeyed a model of a fast kinetics-controlled process followed by a slow product layer diffusion-controlled process. Temperature is the key factor in direct gas-solid carbonation and had a notable influence on both the carbonation conversion and the CO₂ sequestration rate. The optimal CO₂ sequestrating temperature of 395 °C was easily obtained for APCr using a continuous heating experiment. CO₂ content in the flue gas had a definite influence on the CO₂ sequestration rate of the kinetics-controlled process, but almost no influence on the final carbonation conversion. Typical concentrations of SO₂ in the flue gas could not only accelerate the carbonation reaction rate of the product layer diffusion-controlled process, but also could improve the final carbonation conversion. Maximum carbonation conversions of between 68.6% and 77.1% were achieved in a typical flue gas. Features of rapid CO₂ sequestration rate, strong impurities resistance, and high capture conversion for direct gas-solid carbonation were proved in this study, which presents a theoretical foundation for the applied use of this encouraging technology on carbon capture and storage. PMID:23181908

  5. Deactivation of carbon supported palladium catalyst in direct formic acid fuel cell

    A new carbon black supported palladium catalyst for direct formic acid fuel cell applications has been prepared and characterized by X-ray diffraction. Bi-modal distribution of Pd crystallite sizes was observed. The average Pd size for crystallites in small size and large size ranges were about 2.7 nm and 11.2 nm, respectively. The initial activity of the catalyst in the oxidation of formic acid tested in a fuel cell was similar to a commercial well dispersed 20 wt.% Pd/Vulcan. The rates of the fuel cell power decay were measured for formic acid of two purities for various current loadings. The results showed that various mechanisms contribute to the decrease of cell power with time. In direct formic acid fuel cell (DFAFC) fed with a very pure HCOOH accumulation of CO2 gas bubbles in anode catalyst layer is responsible for observed power decay. In DFAFC fed with a pure for analysis (p.a.) grade formic acid the formation of COads poison from the formic acid impurities is the main deactivation reason.

  6. Two-dimensional boron-nitrogen-carbon monolayers with tunable direct band gaps.

    Zhang, Miao; Gao, Guoying; Kutana, Alex; Wang, Yanchao; Zou, Xiaolong; Tse, John S; Yakobson, Boris I; Li, Hongdong; Liu, Hanyu; Ma, Yanming

    2015-07-28

    The search for new candidate semiconductors with direct band gaps of ∼1.4 eV has attracted significant attention, especially among the two-dimensional (2D) materials, which have become potential candidates for next-generation optoelectronics. Herein, we systematically studied 2D B(x)/2N(x/2)C(1-x) (0 optimization method (CALYPSO) in conjunction with density functional theory. Furthermore, we examine more stoichiometries by the cluster expansion technique based on a hexagonal lattice. The results reveal that all monolayer B(x)/2N(x/2)C(1-x) stoichiometries adopt a planar honeycomb character and are dynamically stable. Remarkably, electronic structural calculations show that most of B(x)/2N(x/2)C(1-x) phases possess direct band gaps within the optical range, thereby they can potentially be used in high-efficiency conversion of solar energy to electric power, as well as in p-n junction photovoltaic modules. The present results also show that the band gaps of B(x)/2N(x/2)C(1-x) can be widely tuned within the optical range by changing the concentration of carbon, thus allowing the fast development of band gap engineered materials in optoelectronics. These new findings may enable new approaches to the design of microelectronic devices. PMID:26111661

  7. Impact of California's Air Pollution Laws on Black Carbon and their Implications for Direct Radiative Forcing

    Bahadur, R.; Feng, Y.; Russell, L. M.; Ramanathan, V.

    2010-12-01

    We examine the temporal and the spatial trends in the concentrations of black carbon (BC) - recorded by the IMPROVE monitoring network for the past 20 years - in California. Annual average BC concentrations in California have decreased by about 50% from 0.46 μg m-3 in 1989 to 0.24 μgm-3 in 2008 compared to a corresponding reductions in diesel BC emissions (also about 50%) from a peak of 0.013 Tg Yr-1 in 1990 to 0.006 Tg Yr-1 by 2008. We attribute the observed negative trends to the deployment of diesel particulate filters. Our conclusion that the reduction in diesel emissions is the primary cause of the observed BC reduction is also substantiated by a significant decrease in the ratio of BC to non-BC aerosols. The absorption efficiency of aerosols at visible wavelengths - determined from the observed scattering coefficient and the observed BC - also decreased by about 50% leading to a model-inferred negative direct radiative forcing (a cooling effect) of -1.4 Wm-2 (±60%) over California. Figure 1 (a) Annual means of measured Black Carbon (left axis) and BC fossil fuel emissions (right axis) in California from 1985 to 2008. Error bars correspond to standard deviation between measurements at each station. Dashed lines indicate a linear fit. Aerosol measurements from the IMPROVE network, emission inventories from (1) CARB, (2) [Ito and Penner, 2005] (b) Annual means of BC measured in Southern (South of 35 N), Northern (North of 38 N), and Central California (c) Annual means of measured Sulfate, Nitrate, and OC from IMPROVE network.

  8. Turbostratic-like carbon nitride coatings deposited by industrial-scale direct current magnetron sputtering

    Carbon nitride thin films were deposited by direct current magnetron sputtering in an industrial-scale equipment at different deposition temperatures and substrate bias voltages. The films had N/(N + C) atomic fractions between 0.2 and 0.3 as determined by X-ray photoelectron spectroscopy (XPS). Raman spectroscopy provided insight into the ordering and extension of the graphite-like clusters, whereas nanoindentation revealed information on the mechanical properties of the films. The internal compressive film stress was evaluated from the substrate bending method. At low deposition temperatures the films were amorphous, whereas the film deposited at approximately 380 °C had a turbostratic-like structure as confirmed by high-resolution transmission electron microscopy images. The turbostratic-like film had a highly elastic response when subjected to nanoindentation. When a CrN interlayer was deposited between the film and the substrate, XPS and Raman spectroscopy indicated that the turbostratic-like structure was maintained. However, it was inconclusive whether the film still exhibited an extraordinary elastic recovery. An increased substrate bias voltage, without additional heating and without deposition of an interlayer, resulted in a structural ordering, although not to the extent of a turbostratic-like structure. - Highlights: • Carbon nitride films were deposited by industrial-scale magnetron sputtering. • The deposition temperature and the substrate bias voltage were varied. • A turbostratic-like structure was obtained at an elevated deposition temperature. • The turbostratic-like film exhibited a very high elastic recovery. • The influence of a CrN interlayer on the film properties was investigated

  9. Performance characteristics of a direct carbon fuel cell/thermoelectric generator hybrid system

    Highlights: • A hybrid system is put forward to recover the waste heat generated in DCFCs. • Main irreversible losses in the system are numerically characterized. • Operating current density interval that the TEG exerts its function is determined. • Equivalent maximum power density of the DCFC can be increased more than 50%. • Effects of some important parameters on the performance are discussed. - Abstract: A hybrid system mainly composed of a DCFC (Direct Carbon Fuel Cell), a TEG (Thermoelectric Generator) and a regenerator is put forward, where the DCFC electrochemically converts the chemical energy in the solid carbon into electricity and waste heat, and the TEG further converts the waste heat into electricity for additional power generation. The main irreversibilities in each element of the hybrid system are characterized, and the heat losses between the DCFC and the environment are also considered. Numerical expressions for the power output and efficiency of the hybrid system are respectively derived, from which the general performance characteristics are revealed. The fundamental relationship between the operating current density of the DCFC and the dimensionless electrical current of the TEG is obtained, and thus the region of the operating current density of the DCFC that the TEG exerts its function is determined. By using such a system, the equivalent maximum power density of the hybrid system allows to be 50% larger than that of the sole DCFC system. The effects of the operating current density, operating temperature, heat conductivity, and some integrated parameters on the performance of the hybrid system are discussed

  10. The Orbiting Carbon Observatory (OCO-2): spectrometer performance evaluation using pre-launch direct sun measurements

    Frankenberg, C.; Pollock, R.; Lee, R. A. M.; Rosenberg, R.; Blavier, J.-F.; Crisp, D.; O'Dell, C. W.; Osterman, G. B.; Roehl, C.; Wennberg, P. O.; Wunch, D.

    2015-01-01

    The Orbiting Carbon Observatory-2 (OCO-2), launched on 2 July 2014, is a NASA mission designed to measure the column-averaged CO2 dry air mole fraction, XCO2. Towards that goal, it will collect spectra of reflected sunlight in narrow spectral ranges centered at 0.76, 1.6 and 2.0 μm with a resolving power (λ/Δ λ) of 20 000. These spectra will be used in an optimal estimation framework to retrieve XCO2. About 100 000 cloud free soundings of XCO2 each day will allow estimates of net CO2 fluxes on regional to continental scales to be determined. Here, we evaluate the OCO-2 spectrometer performance using pre-launch data acquired during instrument thermal vacuum tests in April 2012. A heliostat and a diffuser plate were used to feed direct sunlight into the OCO-2 instrument and spectra were recorded. These spectra were compared to those collected concurrently from a nearby high-resolution Fourier Transform Spectrometer that was part of the Total Carbon Column Observing Network (TCCON). Using the launch-ready OCO-2 calibration and spectroscopic parameters, we performed total column scaling fits to all spectral bands and compared these to TCCON results. On 20 April, we detected a CO2 plume from the Los Angeles basin at the JPL site with strongly enhanced short-term variability on the order of 1% (3-4 ppm). We also found good (footprint consistency in retrieved XCO2. The variations in spectral fitting residuals are consistent with signal-to-noise estimates from instrument calibration, while average residuals are systematic and mostly attributable to remaining errors in our knowledge of the CO2 and O2 spectroscopic parameters. A few remaining inconsistencies observed during the tests may be attributable to the specific instrument setup on the ground and will be re-evaluated with in-orbit data.

  11. Multifunctional carbon nanotubes for direct electrochemistry of glucose oxidase and glucose bioassay.

    Wang, Yinling; Liu, Lin; Li, Maoguo; Xu, Shudong; Gao, Feng

    2011-12-15

    Polydopamine (Pdop) has recently been shown to adsorb to a wide variety of surfaces and serves as an adhesion layer to immobilize biological molecules. In this work, the multifunctional carbon nanotube (CNT) composites were prepared though the oxidation of dopamine at room temperature and subsequent electroless silver deposition by mildly stirring. The stable immobilization and direct electron transfer of glucose oxidase were achieved on the composite film modified glassy carbon electrode. The resulting electrode gave a well-defined redox peaks with a formal potential of about -482 mV (vs. SCE) in pH 7.0 buffer. The electron transfer rate constant was estimated to be 3.6 s(-1), due to the combined contribution of Pdop, CNTs and Ag nanoparticles with the help of Nafion. Furthermore, the method for detecting of glucose was proposed based on the decrease of oxygen caused by the enzyme-catalyzed reaction between glucose oxidase (GOD) and glucose. The linear response to glucose ranging from 50.0 μM to 1.1 mM (R(2)=0.9958), with a calculated detection limit of 17.0 μM at a signal-to-noise ratio of 3. The low calculated apparent Michaelis-Menten constant (K(M)(app)) was 5.46 mM, implying the high enzymatic activity and affinity of immobilized GOD for glucose. It can reasonably be expected that this observation might hold true for other noble metal nanostructure-electroactive protein systems, providing a promising platform for the development of biosensors and biofuel cells. PMID:21959226

  12. Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over CeO2(X)-ZnO(1-X) nano-catalysts.

    Kang, Ki Hyuk; Joe, Wangrae; Lee, Chang Hoon; Kim, Mieock; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2013-12-01

    CeO2(X)-ZnO(1-X) (X = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) nano-catalysts were prepared by a co-precipitation method with a variation of CeO2 content (X, mol%), and they were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of CeO2(X)-ZnO(1-X) nano-catalysts was well confirmed by XRD analysis. The amount of DMC produced over CeO2(X)-ZnO(1-X) catalysts exhibited a volcano-shaped curve with respect to CeO2 content. Acidity and basicity of CeO2(X)-ZnO(1-X) nano-catalysts were measured by NH3-TPD and CO2-TPD experiments, respectively, to elucidate the effect of acidity and basicity on the catalytic performance in the reaction. It was revealed that the catalytic performance of CeO2(X)-ZnO(1-X) nano-catalysts was closely related to the acidity and basicity of the catalysts. Amount of dimethyl carbonate increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, CeO2(0.7)-ZnO(0.3) with the largest acidity and basicity showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. PMID:24266202

  13. NiO/CeO2-ZnO nano-catalysts for direct synthesis of dimethyl carbonate from methanol and carbon dioxide.

    Kang, Ki Hyuk; Lee, Chang Hoon; Kim, Dong Baek; Jang, Boknam; Song, In Kyu

    2014-11-01

    XNiO/CeO2(0.7)-ZnO(0.3) (X = 0, 1, 5, 10, and 15) nano-catalysts were prepared by a wet impregnation method with a variation of NiO content (X, wt%). The prepared catalysts were then applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Successful formation of XNiO/CeO2(0.7)-ZnO(0.3) nano-catalysts was confirmed by XRD and ICP-AES analyses. Acidity and basicity of XNiO/CeO2-ZnO were measured by NH3-TPD (temperature-programmed desorption) and CO2-TPD experiments, respectively, with an aim of elucidating the effect of acidity and basicity of the catalysts on the catalytic performance in the reaction. It was revealed that the catalytic activity of XNiO/CeO2(0.7)-ZnO(0.3) was closely related to both acidity and basicity of the catalysts. The amount of dimethyl carbonate produced over XNiO/CeO2(0.7)-ZnO(0.3) increased with increasing acidity and basicity of the catalysts. Thus, both acidity and basicity of the catalysts played important roles in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. PMID:25958586

  14. Direct observation of spin-injection in tyrosinate-functionalized single-wall carbon nanotubes

    Tsoufis, Theodoros; Ampoumogli, Asem; Gournis, Dimitrios; Georgakilas, Vasilios; Jankovic, Lubos; Christoforidis, Konstantinos C.; Deligiannakis, Yiannis; Mavrandonakis, Andreas; Froudakis, George E.; Maccallini, Enrico; Rudolf, Petra; Mateo-Alonso, Aurelio; Prato, Maurizio

    2014-01-01

    In this work, we report on the interaction of a tyrosinate radical with single wall carbon nanotubes (CNT). The tyrosinate radical was formed from tyrosine (ester) by Fenton's reagent and, reacted in situ with carbon nanotubes resulting in novel tyrosinated carbon nanotube derivatives. The covalent

  15. Experimental Investigation on Effect of Carbon Nanotubes and Carbon Fibres on the Behavior of Plain Cement Mortar Composite Round Bars under Direct Tension

    Hunashyal, A. M.; Sagar V. Tippa; S. S. Quadri; Banapurmath, N. R.

    2011-01-01

    This paper investigates the behavior of reinforced cement mortar composite round bars with multiwalled carbon nanotubes (MWCNTs) and carbon fibers (CFs). The percentage of CFs was fixed at 2.25 wt% of cement, while the percentage of MWCNTs was fixed at 0.5, by wt% of cement. Dispersion of both MWCNTs and CFs was carried out using ultrasonic energy method. Composite round bars were tested under direct tension in order to evaluate their mechanical properties such as ultimate load, deflection cr...

  16. The direct imaging and observed packing behaviour of othro-carborane molecules within single walled carbon nanotubes

    Ortho-carborane molecules have been inserted into single walled carbon nanotubes (SWNTs) and imaged directly by high resolution transmission electron microscopy (HRTEM). Direct imaging revealed that both discrete molecules and zig-zag 1D chains of o-carborane molecules were observed to pack into SWNT capillaries. Upon further e-beam irradiation, partial decomposition and rearrangement of clusters of o-carborane molecules was observed

  17. Direct growth of carbon nanotubes on metal surfaces without an external catalyst and nanocomposite production

    Baddour, Carole Emilie

    The research work presented in this thesis deals with carbon nanotubes (CNTs), an allotrope of carbon with a cylindrical structure consisting of a rolled up graphene sheet. CNTs are generally produced by the decomposition of a carbon source in the presence of a metal catalyst at elevated temperatures. CNTs have outstanding properties and have attracted immense attention in both industry and academia. However, the development of commercial applications of CNTs is slow due to limitations in the large scale production of CNTs and their high cost. Another limitation is the interface resistance generated by external catalyst nanoparticles used in traditional CNT growth methods. In order to eliminate the interface resistance and simultaneously provide CNT growth over large surfaces and varying geometries, a method called direct CNT growth is established to enable the extraction of the CNT structure directly from the metal surface. The novel process for the production of CNTs developed in the present thesis is applied to planar surfaces and spherical particles made of stainless steel (SS) 304. The method is based on the establishment of nanometer scale structures at the surface which act as catalyst nanoparticles while at the same time being integral parts of the material. It uses first a mild chemical etching of the surface, followed by a specific heat treatment performed using either standard chemical vapour deposition (standard-CVD) or fluidized bed CVD (FBCVD) techniques. Acetylene (C2H2) is used as the carbon source and SS 304 acts as both the catalyst and the substrate in the growth process. This direct CNT growth with this substrate dual function eliminates the need of external catalyst nanoparticles deposited onto the surface. The active sites necessary for CNT growth are tailored on the SS itself by means of the two-step treatment process. MWNTs of 20-70 nm in diameter are produced. The CNTs are characterized by Raman Spectroscopy, Thermogravimetric analysis (TGA

  18. Markedly enhanced direct radiative forcing of black carbon particles under polluted urban environments

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti; Zeng, Liming; Shao, Min; Wu, Yusheng; Zheng, Jun; Wang, Yuan; Collins, Don; Zhang, Renyi

    2016-04-01

    Black carbon (BC) particles, produced from incomplete fossil fuel combustion and biomass burning, are ubiquitous in the atmosphere and have profound impacts on air quality, human health, weather, and climate. For example, in areas identified as aerosol hotspots, which include many urban centers and megacities worldwide, solar heating by BC particles has been shown to be comparable to warming due to the greenhouse gases2. Although BC represents a key short-lived climate forcer, its direct radiative forcing remains highly uncertain. In particular, the available results of absorption enhancement of BC particles during atmospheric aging are conflicting from the previous studies, leading to a large uncertainty in global radiative transfer calculation. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China and Houston, US, using a novel chamber approach. BC aging exhibits two distinct stages - initial transformation from a fractal to spherical morphology with little absorption variation and the subsequent growth of fully compact particles with a maximum absorption enhancement factor of 2.4. The variation in BC direct radiative forcing is highly dependent of the rate and timescale of aging, with an estimated increase of 0.45 (0.21 - 0.80) W m-2 from fresh to fully aged particles. Our results reveal a high climatic impact in polluted environments due to rapid aging and a clear distinction between urban cities in developed and developing countries for BC particles, highlighting a larger than recognized co-benefit in air quality improvement and climate protection by BC mediation.

  19. Development of an Airborne System for Direct Validation of Regional Carbon Flux Estimates

    Wolfe, G.; Kawa, S. R.; Hanisco, T. F.; Newman, P. A.

    2015-12-01

    Global distributions of greenhouse gas (GHG) sources and sinks, principally CO2 and CH4, and characterization of the processes that control them, comprise a key uncertainty in projections of future climate. A broad spectrum of tools is currently used to characterize these processes. Top-down inversions of orbital GHG column observations (e.g. ACOS/GOSAT and OCO-2) provide a global perspective, but little information is available to validate these estimates. Indirect (boundary-layer budget) or direct (tower-based eddy covariance) surface flux measurements can provide bottom-up constraints, but the former is typically focused on large point and area emission sources while the latter relies on sparse networks with limited spatial coverage. Aircraft are an ideal platform to bridge the flux representation scale from kilometers (as measured from towers) to the tens or hundreds of kilometers relevant to satellite observations and global models. In light of current measurement gaps and the emerging need for direct validation of GHG surface flux estimates, NASA is developing a sophisticated facility for airborne eddy covariance observations of carbon dioxide, methane, water vapor and other trace gases. Three components comprise the core measurement system: i) the NASA Wallops Sherpa, which is ideal for airborne eddy covariance due to its substantial payload and the ability to fly low and slow, ii) commercial GHG sensors optimized for airborne flux measurements, and iii) a custom gust-probe system for high-fidelity measurements of vertical wind velocity. These systems will be discussed in detail, along with future plans for deployment and application of measurements to improving GHG flux estimates on local, regional and global scales.

  20. Modelling the carbon and nitrogen balances of direct land use changes from energy crops in Denmark

    Hamelin, Lorie; Jørgensen, Uffe; Petersen, Bjørn Molt;

    2012-01-01

    and perennials), two soil types (sandy loam and sand), two climate types (wet and dry), three initial soil carbon level (high, average, low), two time horizons for soil carbon changes (20 and 100 years), two residues management practices (removal and incorporation into soil) as well as three soil...... carbon turnover rate reductions in response to the absence of tillage for some perennial crops (0%, 25%, 50%). For all crop systems, nutrient balances, balances between above- and below-ground residues, soil carbon changes, biogenic carbon dioxide flows, emissions of nitrogen compounds and losses of...... macro- and micronutrients are presented. The inventory results highlight Miscanthus as a promising energy crop, indicating it presents the lowest emissions of nitrogen compounds, the highest amount of carbon dioxide sequestrated from the atmosphere, a relatively high carbon turnover efficiency and...

  1. Rate-independent dissipation and loading direction effects in compressed carbon nanotube arrays

    Arrays of nominally-aligned carbon nanotubes (CNTs) under compression deform locally via buckling, exhibit a foam-like, dissipative response, and can often recover most of their original height. We synthesize millimeter-scale CNT arrays and report the results of compression experiments at different strain rates, from 10−4 to 10−1 s−1, and for multiple compressive cycles to different strains. We observe that the stress–strain response proceeds independently of the strain rate for all tests, but that it is highly dependent on loading history. Additionally, we examine the effect of loading direction on the mechanical response of the system. The mechanical behavior is modeled using a multiscale series of bistable springs. This model captures the rate independence of the constitutive response, the local deformation, and the history-dependent effects. We develop here a macroscopic formulation of the model to represent a continuum limit of the mesoscale elements developed previously. Utilizing the model and our experimental observations we discuss various possible physical mechanisms contributing to the system’s dissipative response. (paper)

  2. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments.

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R; Collins, Donald R; Molina, Mario J; Zhang, Renyi

    2016-04-19

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries. PMID:27035993

  3. Directing carbon nanotubes from aqueous phase to o/w interface for heavy metal uptaking.

    Gao, Lili; Yin, Huayi; Mao, Xuhui; Zhu, Hua; Xiao, Wei; Wang, Dihua

    2015-09-01

    Separation and reuse of dispersed nanoparticles are major obstacles to the extensive application of nano-sized absorbents in wastewater treatment. Herein, we demonstrate the capability of directing acid-oxidized carbon nanotubes (CNTs) as the transfer vehicles of heavy metal ions from simulated wastewater. The heavy metal-loaded CNTs can be readily separated from the aqueous phase via the aggregation process at an oil/water (o/w) interface. The minimum surfactant amount to achieve 99 % transfer ratio (Tr) of 100 mg/L CNTs from water phase to o/w interface was ∼0.01 mM. The adsorption experiments showed that the removal efficiency of the divalent lead ions increased with an increase in CNT mass, and the subsequent addition of cetyltrimethylammonium bromide (CTAB) surfactant did not negatively impact the removal of soluble divalent lead species (Pb(II)). In a wide region of pH and ionic strength, both the decontamination of Pb(II) and the transfer of CNTs from water phase to o/w interface can be accomplished successively. The method presented in this study may be developed as a generic one for collecting or recycling the pollutant-loaded nano-sized absorbents. PMID:25966885

  4. Direct electrochemistry and electrocatalysis of myoglobin immobilized on zirconia/multi-walled carbon nanotube nanocomposite

    Liang, Ruping; Deng, Minqiang; Cui, Sanguan; Chen, Hong [Department of Chemistry and Institute for Advanced Study, Nanchang University, Nanchang 330031 (China); Qiu, Jianding, E-mail: jdqiu@ncu.edu.cn [Department of Chemistry and Institute for Advanced Study, Nanchang University, Nanchang 330031 (China)

    2010-12-15

    Zirconia/multi-walled carbon nanotube (ZrO{sub 2}/MWCNT) nanocomposite was prepared by hydrothermal treatment of MWCNTs in ZrOCl{sub 2}.8H{sub 2}O aqueous solution. The morphology and structure of the synthesized ZrO{sub 2}/MWCNT nanocomposite were characterized by transmission electron microscopy and X-ray diffraction analysis. It was found that ZrO{sub 2} nanoparticles homogeneously distributed on the sidewall of MWCNTs. Myoglobin (Mb), as a model protein to investigate the nanocomposite, was immobilized on ZrO{sub 2}/MWCNT nanocomposite. Ultraviolet-visible spectroscopy and electrochemical measurements showed that the nanocomposite could retain the bioactivity of the immobilized Mb to a large extent. The Mb immobilized in the composite showed excellent direct electrochemistry and electrocatalytic activity to the reduction of hydrogen peroxide (H{sub 2}O{sub 2}). The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 1.0 to 116.0 {mu}M with the limit of detection of 0.53 {mu}M (S/N = 3). The ZrO{sub 2}/MWCNT nanocomposite provided a good biocompatible matrix for protein immobilization and biosensors preparation.

  5. The contribution of foreign direct investment to clean energy use, carbon emissions and economic growth

    The paper investigates the contributions of foreign direct investment (FDI) net inflows to clean energy use, carbon emissions, and economic growth. The paper employs cointegration tests to examine a long-run equilibrium relationship among the variables and fixed effects models to examine the magnitude of FDI contributions to the other variables. The paper analyzes panel data of 19 nations of the G20 from 1971 to 2009. The test results indicate that FDI has played an important role in economic growth for the G20 whereas it limits its impact on an increase in CO2 emissions in the economies. The research finds no compelling evidence of FDI link with clean energy use. Given the results, the paper discusses FDI's potential role in achieving green growth goals. - Highlights: ► FDI inflows strongly lead to economic growth in the G20. ► FDI inflows lead to an increase in energy use in the G20. ► FDI inflows are in no relation to CO2 emissions in the G20. ► FDI inflows are in no relation to clean energy use in the G20. ► Economic growth is in negative relation to CO2 emissions in the G20

  6. Direct measurement of radioactive carbon in Vietnamese vodkas by Liquid Scintillation Counter

    From the view point of applying to laboratory exercise of radioactivity measurement by a Liquid Scintillation Counter (LSC), Vietnamese vodkas have specific features as measurement samples, for example, they are colorless, have high ethanol content, and only very few organic materials are included. Investigation was made to make sure that the Vietnamese vodkas are appropriate or not as a measurement sample for the LSC exercise. Direct measurements of 14C without any chemical pre-treatment were made on both radioactive concentrations and specific activities of three kinds of Vietnamese vodka and also pure ethanol reagent. The LSC measurements reveal that estimated 14C concentration is proportional to ethanol content in samples and that specific activity of 14C shows good agreement among the Vietnamese vodkas and pure ethanol, as well as the reference value of 0.25 Bq/g of Carbon. Thus the conclusion is derived that the Vietnamese vodkas can be applied with high accuracy to the LSC exercise as measurement samples. (author)

  7. Direct electrochemistry of hemoglobin entrapped in dextran film on carbon ionic liquid electrode

    Xiaoqing Li; Yan Wang; Xiaoying Sun; Tianrong Zhan; Wei Sun

    2010-03-01

    Direct electrochemistry of hemoglobin (Hb) entrapped in the dextran (De) film on the surface of a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6) modified carbon paste electrode (CILE) has been investigated. UV-Vis and FT-IR spectroscopy showed that Hb retained its native structure in the De film. Scanning electron microscopy (SEM) indicated an uniform film was formed on the electrode surface. Cyclic voltammetric experiments indicated that the electron transfer efficiency between Hb and the electrode was greatly improved due to the presence of the De film and ionic liquid, which provided a biocompatible and higher conductive interface. A pair of well-defined and quasi-reversible redox peak was obtained with the anodic and cathodic peaks located at -0.195 V and -0.355 V in pH 7.0 phosphate buffer solution, respectively. The electrochemical parameters were calculated by investigating the relationship of the peak potential with the scan rate. The fabricated De/Hb/CILE showed good electrocatalytic ability to the reduction of H2O2 with the linear concentration range from 4.0 × 10-6 to 1.5 × 10-5 mol/L and the apparent Michaelis-Menten constant ($K_{M}^{\\text{app}}$) for the electrocatalytic reaction was calculated as 0.17 M.

  8. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Levy Zamora, Misti; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R.; Collins, Donald R.; Molina, Mario J.

    2016-04-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two distinct stages, i.e., initial transformation from a fractal to spherical morphology with little absorption variation and subsequent growth of fully compact particles with a large absorption enhancement. The timescales to achieve complete morphology modification and an absorption amplification factor of 2.4 for BC particles are estimated to be 2.3 h and 4.6 h, respectively, in Beijing, compared with 9 h and 18 h, respectively, in Houston. Our findings indicate that BC under polluted urban environments could play an essential role in pollution development and contribute importantly to large positive radiative forcing. The variation in direct radiative forcing is dependent on the rate and timescale of BC aging, with a clear distinction between urban cities in developed and developing countries, i.e., a higher climatic impact in more polluted environments. We suggest that mediation in BC emissions achieves a cobenefit in simultaneously controlling air pollution and protecting climate, especially for developing countries.

  9. Manufacturing polymer/carbon nanotube composite using a novel direct process

    A direct process for manufacturing polymer carbon nanotube (CNT)-based composite yarns is reported. The new approach is based on a modified dry spinning method of CNT yarn and gives a high alignment of the CNT bundle structure in yarns. The aligned CNT structure was combined with a polymer resin and, after being stressed through the spinning process, the resin was cured and polymerized, with the CNT structure acting as reinforcement in the composite. Thus the present method obviates the need for special and complex treatments to align and disperse CNTs in a polymer matrix. The new process allows us to produce a polymer/CNT composite with properties that may satisfy various engineering specifications. The structure of the yarn was investigated using scanning electron microscopy coupled with a focused-ion-beam system. The tensile behavior was characterized using a dynamic mechanical analyzer. Fourier transform infrared spectrometry was also used to chemically analyze the presence of polymer on the composites. The process allows development of polymer/CNT-based composites with different mechanical properties suitable for a range of applications by using various resins.

  10. Manufacturing polymer/carbon nanotube composite using a novel direct process

    Tran, C.-D.; Lucas, S.; Phillips, D. G.; Randeniya, L. K.; Baughman, R. H.; Tran-Cong, T.

    2011-04-01

    A direct process for manufacturing polymer carbon nanotube (CNT)-based composite yarns is reported. The new approach is based on a modified dry spinning method of CNT yarn and gives a high alignment of the CNT bundle structure in yarns. The aligned CNT structure was combined with a polymer resin and, after being stressed through the spinning process, the resin was cured and polymerized, with the CNT structure acting as reinforcement in the composite. Thus the present method obviates the need for special and complex treatments to align and disperse CNTs in a polymer matrix. The new process allows us to produce a polymer/CNT composite with properties that may satisfy various engineering specifications. The structure of the yarn was investigated using scanning electron microscopy coupled with a focused-ion-beam system. The tensile behavior was characterized using a dynamic mechanical analyzer. Fourier transform infrared spectrometry was also used to chemically analyze the presence of polymer on the composites. The process allows development of polymer/CNT-based composites with different mechanical properties suitable for a range of applications by using various resins.

  11. Manufacturing polymer/carbon nanotube composite using a novel direct process

    Tran, C-D; Tran-Cong, T [Computational Engineering and Science Research Centre (CESRC), Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, QLD 4350 (Australia); Lucas, S; Phillips, D G [CSIRO Materials Science and Engineering, PO Box 21, Belmont, VIC 3216 (Australia); Randeniya, L K [CSIRO Materials Science and Engineering, PO Box 218, Lindfield, NSW 2070 (Australia); Baughman, R H, E-mail: canh-dung.tran@usq.edu.au [NanoTech Institute, University of Texas at Dallas, Richardson, TX 75083-0688 (United States)

    2011-04-08

    A direct process for manufacturing polymer carbon nanotube (CNT)-based composite yarns is reported. The new approach is based on a modified dry spinning method of CNT yarn and gives a high alignment of the CNT bundle structure in yarns. The aligned CNT structure was combined with a polymer resin and, after being stressed through the spinning process, the resin was cured and polymerized, with the CNT structure acting as reinforcement in the composite. Thus the present method obviates the need for special and complex treatments to align and disperse CNTs in a polymer matrix. The new process allows us to produce a polymer/CNT composite with properties that may satisfy various engineering specifications. The structure of the yarn was investigated using scanning electron microscopy coupled with a focused-ion-beam system. The tensile behavior was characterized using a dynamic mechanical analyzer. Fourier transform infrared spectrometry was also used to chemically analyze the presence of polymer on the composites. The process allows development of polymer/CNT-based composites with different mechanical properties suitable for a range of applications by using various resins.

  12. Broadband Tunable, Polarization-Selective and Directional Emission of (6,5) Carbon Nanotubes Coupled to Plasmonic Crystals

    2016-01-01

    We demonstrate broadband tunability of light emission from dense (6,5) single-walled carbon nanotube thin films via efficient coupling to periodic arrays of gold nanodisks that support surface lattice resonances (SLRs). We thus eliminate the need to select single-walled carbon nanotubes (SWNTs) with different chiralities to obtain narrow linewidth emission at specific near-infrared wavelengths. Emission from these hybrid films is spectrally narrow (20–40 meV) yet broadly tunable (∼1000–1500 nm) and highly directional (divergence simulations are applied to correlate the increased local electric fields around the nanodisks with the observed enhancement of directional emission. The ability to control the emission properties of a single type of near-infrared emitting SWNTs over a wide range of wavelengths will enable application of carbon nanotubes in multifunctional photonic devices. PMID:27105249

  13. Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

    Margalef, Pere; Samuelsen, Scott [National Fuel Cell Research Center (NFCRC), University of California, Irvine, CA 92697-3550 (United States)

    2010-09-01

    A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two ''off the shelf'' units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow

  14. Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration.

    Veetil, Sanoopkumar Puthiya; Pasquier, Louis-César; Blais, Jean-François; Cecchi, Emmanuelle; Kentish, Sandra; Mercier, Guy

    2015-09-01

    Mineral carbonation of serpentinite mining residue offers an environmentally secure and permanent storage of carbon dioxide. The strategy of using readily available mining residue for the direct treatment of flue gas could improve the energy demand and economics of CO2 sequestration by avoiding the mineral extraction and separate CO2 capture steps. The present is a laboratory scale study to assess the possibility of CO2 fixation in serpentinite mining residues via direct gas-solid reaction. The degree of carbonation is measured both in the absence and presence of water vapor in a batch reactor. The gas used is a simulated gas mixture reproducing an average cement flue gas CO2 composition of 18 vol.% CO2. The reaction parameters considered are temperature, total gas pressure, time, and concentration of water vapor. In the absence of water vapor, the gas-solid carbonation of serpentinite mining residues is negligible, but the residues removed CO2 from the feed gas possibly due to reversible adsorption. The presence of small amount of water vapor enhances the gas-solid carbonation, but the measured rates are too low for practical application. The maximum CO2 fixation obtained is 0.07 g CO2 when reacting 1 g of residue at 200 °C and 25 barg (pCO2 ≈ 4.7) in a gas mixture containing 18 vol.% CO2 and 10 vol.% water vapor in 1 h. The fixation is likely surface limited and restricted due to poor gas-solid interaction. It was identified that both the relative humidity and carbon dioxide-water vapor ratio have a role in CO2 fixation regardless of the percentage of water vapor. PMID:25940479

  15. Synthesis of free-standing carbon nanohybrid by directly growing carbon nanotubes on air-sprayed graphene oxide paper and its application in supercapacitor

    We report the synthesis of a free-standing two dimensional carbon nanotube (CNT)-reduced graphene oxide (rGO) hybrid by directly growing CNTs on air-sprayed GO paper. As a result of the good integration between CNTs and thermally reduced GO film during chemical vapor deposition, excellent electrical conductivity (2.6×104 S/m), mechanical flexibility (electrical resistance only increases 1.1% after bent to 90° for 500 times) and a relatively large surface area (335.3 m2/g) are achieved. Two-electrode supercapacitor assembled using the CNT–rGO hybrids in ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate) shows excellent stability upon 500 bending cycles with the gravimetric energy density measuring 23.7 Wh/kg and a power density of 2.0 kW/kg. Furthermore, it shows an impedance phase angle of −64.4° at a frequency of 120 Hz, suggesting good potentials for 120 Hz alternating current line filtering applications. - Graphical abstract: Flexible and highly conductive carbon nanotube-reduced graphene oxide nanohybrid. - Highlights: • Direct growth of carbon nanotubes by chemical vapor deposition on air-sprayed graphene oxide paper. • Two-dimensional carbon nanohybrid with excellent conductivity and mechanical flexibility. • Supercapacitor with excellent performance stability upon mechanical deformation for flexible electronics applications. • Supercapacitor with high impedance phase angle for 120 Hz alternating current line filtering applications

  16. Synthesis of free-standing carbon nanohybrid by directly growing carbon nanotubes on air-sprayed graphene oxide paper and its application in supercapacitor

    Wei, Li; Jiang, Wenchao; Yuan, Yang; Goh, Kunli; Yu, Dingshan [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore); Wang, Liang [School of Chemistry and Chemical Engineering, Tianjin University of Technology, Tianjin 300384 (China); Chen, Yuan, E-mail: chenyuan@ntu.edu.sg [School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459 (Singapore)

    2015-04-15

    We report the synthesis of a free-standing two dimensional carbon nanotube (CNT)-reduced graphene oxide (rGO) hybrid by directly growing CNTs on air-sprayed GO paper. As a result of the good integration between CNTs and thermally reduced GO film during chemical vapor deposition, excellent electrical conductivity (2.6×10{sup 4} S/m), mechanical flexibility (electrical resistance only increases 1.1% after bent to 90° for 500 times) and a relatively large surface area (335.3 m{sup 2}/g) are achieved. Two-electrode supercapacitor assembled using the CNT–rGO hybrids in ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate) shows excellent stability upon 500 bending cycles with the gravimetric energy density measuring 23.7 Wh/kg and a power density of 2.0 kW/kg. Furthermore, it shows an impedance phase angle of −64.4° at a frequency of 120 Hz, suggesting good potentials for 120 Hz alternating current line filtering applications. - Graphical abstract: Flexible and highly conductive carbon nanotube-reduced graphene oxide nanohybrid. - Highlights: • Direct growth of carbon nanotubes by chemical vapor deposition on air-sprayed graphene oxide paper. • Two-dimensional carbon nanohybrid with excellent conductivity and mechanical flexibility. • Supercapacitor with excellent performance stability upon mechanical deformation for flexible electronics applications. • Supercapacitor with high impedance phase angle for 120 Hz alternating current line filtering applications.

  17. Enhanced direct electron transfer between laccase and hierarchical carbon microfibers/carbon nanotubes composite electrodes. Comparison of three enzyme immobilization methods

    Three immobilization protocols were investigated with respect to direct electron transfer between hierarchical carbon microfibers/carbon nanotubes composite material on graphite rod electrodes and Trametes hirsuta laccase. Immobilization was done by covalent binding of laccase to aminophenyl-modified electrodes via amide-bond formation with carboxylic acid residues or imino-bond formation with aldehyde groups introduced by oxidation of sugar residues of the enzyme's glycosylation shell. Moreover, immobilization was achieved by adsorbing laccase to electrodes hydrophilized with pyrene-hexanoic acid. High current densities for biocatalytic oxygen reduction were obtained for all immobilization strategies. The formation of the imino bonds let to the binding of laccase in close to 100% direct electron transfer configuration and consequently to the highest oxygen reduction currents.

  18. Research Update: Direct conversion of amorphous carbon into diamond at ambient pressures and temperatures in air

    We report on fundamental discovery of conversion of amorphous carbon into diamond by irradiating amorphous carbon films with nanosecond lasers at room-temperature in air at atmospheric pressure. We can create diamond in the form of nanodiamond (size range <100 nm) and microdiamond (>100 nm). Nanosecond laser pulses are used to melt amorphous diamondlike carbon and create a highly undercooled state, from which various forms of diamond can be formed upon cooling. The quenching from the super undercooled state results in nucleation of nanodiamond. It is found that microdiamonds grow out of highly undercooled state of carbon, with nanodiamond acting as seed crystals

  19. Influence of selected coal contaminants on graphitic carbon electro-oxidation for application to the direct carbon fuel cell

    Tulloch, John; Allen, Jessica; Wibberley, Louis; Donne, Scott

    2014-08-01

    A novel method examining the fundamental electrochemical behaviour of carbon is outlined here involving the use of a half cell set-up and solid sacrificial anode. Using this method, electrochemical oxidation of graphite is assessed using selective contamination of a graphite electrode with major coal contaminants identified in selected Australian black coals using X-ray diffraction. Contaminants identified include anatase, alumina, pyrite, quartz, kaolin and montmorillonite. From the systematic introduction of these contaminants it is shown that clay materials, such as kaolin and montmorillonite, act catalytically to increase the rate of graphite oxidation. Metal oxides and sulfides such as anatase, alumina and pyrite give a limited increase in the normalised current, whereas quartz gives a significant decrease in performance. This demonstrates a clear effect of the solid phase interaction of these contaminants on the electrochemical oxidation of graphite since the same effect is not observed when the contaminants are added instead to the molten carbonate electrolyte.

  20. Precipitation legacy effects on dryland ecosystem carbon fluxes: direction, magnitude and biogeochemical carryovers

    Shen, W.; Jenerette, G. D.; Hui, D.; Scott, R. L.

    2016-01-01

    The precipitation legacy effect, defined as the impact of historical precipitation (PPT) on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground net primary production (ANPP) and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C) fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in the southwestern USA, calibrated and evaluated the model performance based on 7 years of eddy-covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual PPT legacy effects over a 30-year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy) always increased subsequent net ecosystem production (NEP) whereas increasing the previous period/year PPT (wet legacy) decreased NEP. The simulated dry-legacy impacts mostly increased subsequent gross ecosystem production (GEP) and reduced ecosystem respiration (Re), but the wet legacy mostly reduced GEP and increased Re. Although the direction and magnitude of GEP and Re responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. The carryover of soil N between periods/years was mainly responsible for the GEP responses, while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the Re responses. These simulation results suggest that previous PPT conditions can exert substantial legacy impacts on current ecosystem C balance, which should

  1. Source sector and region contributions to concentration and direct radiative forcing of black carbon in China

    Li, Ke; Liao, Hong; Mao, Yuhao; Ridley, David A.

    2016-01-01

    We quantify the contributions from five domestic emission sectors (residential, industry, transportation, energy, and biomass burning) and emissions outside of China (non-China) to concentration and direct radiative forcing (DRF) of black carbon (BC) in China for year 2010 using a nested-grid version of the global chemical transport model (GEOS-Chem) coupled with a radiative transfer model. The Hemispheric Transport of Air Pollution (HTAP) anthropogenic emissions of BC for year 2010 are used in this study. Simulated surface-layer BC concentrations in China have strong seasonal variations, which exceed 9 μg m-3 in winter and are about 1-5 μg m-3 in summer in the North China Plain and the Sichuan Basin. Residential sector is simulated to have the largest contribution to surface BC concentrations, by 5-7 μg m-3 in winter and by 1-3 μg m-3 in summer, reflecting the large emissions from winter heating and the enhanced wet deposition during summer monsoon. The contribution from industry sector is the second largest and shows relatively small seasonal variations; the emissions from industry sector contribute 1-3 μg m-3 to BC concentrations in the North China Plain and the Sichuan Basin. The contribution from transportation sector is the third largest, followed by that from biomass burning and energy sectors. The non-China emissions mainly influence the surface-layer concentrations of BC in western China; about 70% of surface-layer BC concentration in the Tibet Plateau is attributed to transboundary transport. Averaged over all of China, the all-sky DRF of BC at the top of the atmosphere (TOA) is simulated to be 1.22 W m-2. Sensitivity simulations show that the TOA BC direct radiative forcings from the five domestic emission sectors of residential, industry, energy, transportation, biomass burning, and non-China emissions are 0.44, 0.27, 0.01, 0.12, 0.04, and 0.30 W m-2, respectively. The domestic and non-China emissions contribute 75% and 25% to BC DRF in China

  2. First direct evidence of sedimentary carbonate recycling in subduction-related xenoliths.

    Liu, Yongsheng; He, Detao; Gao, Changgui; Foley, Stephen; Gao, Shan; Hu, Zhaochu; Zong, Keqing; Chen, Haihong

    2015-01-01

    Carbon in rocks and its rate of exchange with the exosphere is the least understood part of the carbon cycle. The amount of carbonate subducted as sediments and ocean crust is poorly known, but essential to mass balance the cycle. We describe carbonatite melt pockets in mantle peridotite xenoliths from Dalihu (northern China), which provide firsthand evidence for the recycling of carbonate sediments within the subduction system. These pockets retain the low trace element contents and δ(18)OSMOW = 21.1 ± 0.3 of argillaceous carbonate sediments, representing wholesale melting of carbonates instead of filtered recycling of carbon by redox freezing and melting. They also contain microscopic diamonds, partly transformed to graphite, indicating that depths >120 km were reached, as well as a bizarre mixture of carbides and metal alloys indicative of extremely reducing conditions. Subducted carbonates form diapirs that move rapidly upwards through the mantle wedge, reacting with peridotite, assimilating silicate minerals and releasing CO2, thus promoting their rapid emplacement. The assimilation process produces very local disequilibrium and divergent redox conditions that result in carbides and metal alloys, which help to interpret other occurrences of rock exhumed from ultra-deep conditions. PMID:26100577

  3. Template directed formation of nanoparticle decorated multi-walled carbon nanotube bundles with uniform diameter

    Bundles of multi-walled carbon nanotubes of uniform diameter decorated with Ni nanoparticles were synthesized using mesoporous silicates as templates. The ordered morphology and the narrow pore size distribution of mesoporous silicates provide an ideal platform to synthesize uniformly sized carbon nanotubes. In addition, homogeneous sub-10 nm pore sizes of the templates allow in situ formation of catalytic nanoparticles with uniform diameters which end up decorating the carbon nanotubes. The resulting carbon nanotubes are multi-walled with a uniform diameter corresponding to the pore diameter of the template used during the synthesis that are decorated with the catalysts used to synthesize them. They have a narrow size distribution which can be used in many energy related fields of research.

  4. A global simulation of brown carbon: implications for photochemistry and direct radiative effect

    Jo, Duseong S.; Park, Rokjin J; Lee, Seungun; Kim, Sang-Woo; Zhang, Xiaolu

    2016-01-01

    Recent observations suggest that a certain fraction of organic carbon (OC) aerosol effectively absorbs solar radiation, which is also known as brown carbon (BrC) aerosol. Despite much observational evidence of its presence, very few global modelling studies have been conducted because of poor understanding of global BrC emissions. Here we present an explicit global simulation of BrC in a global 3-D chemical transport model (GEOS-Chem), including global BrC emission estimates...

  5. Mechanisms of microbial carbon sequestration in the ocean – future research directions

    N. Jiao

    2014-06-01

    Full Text Available This paper reviews progress on understanding biological carbon sequestration in the ocean with special reference to the microbial formation and transformation of recalcitrant dissolved organic carbon (RDOC, the microbial carbon pump (MCP. We propose that RDOC is a relative concept with a wide continuum of recalcitrance. Most RDOC compounds maintain their levels of recalcitrance only in a specific environmental context (RDOCt. The ocean RDOC pool also contains compounds that may be inaccessible to microbes due to their extremely low concentration (RDOCc. This differentiation allows us to appreciate the linkage between microbial source and RDOC composition on a range of temporal and spatial scales. Analyses of biomarkers and isotopic records show intensive MCP processes in the anoxic Proterozoic oceans when the MCP could have played a significant role in regulating climate. Understanding the dynamics of the MCP in conjunction with the better constrained biological pump (BP over geological timescales could help to predict future climate trends. Integration of the MCP and the BP will require new research approaches and opportunities. Major goals include understanding the interactions between particulate organic carbon (POC and RDOC that contribute to sequestration efficiency, and the concurrent determination of the chemical composition of organic carbon, microbial community composition and enzymatic activity. Molecular biomarkers and isotopic tracers should be employed to link water column processes to sediment records, as well as to link present-day observations to paleo-evolution. Ecosystem models need to be developed based on empirical relationships derived from bioassay experiments and field investigations in order to predict the dynamics of carbon cycling along the stability continuum of POC and RDOC under potential global change scenarios. We propose that inorganic nutrient input to coastal waters may reduce the capacity for carbon

  6. Precipitation legacy effects on dryland ecosystem carbon fluxes: direction, magnitude and biogeochemical carryovers

    W. Shen

    2015-07-01

    Full Text Available The precipitation legacy effect, defined as the impact of historical precipitation (PPT on extant ecosystem dynamics, has been recognized as an important driver in shaping the temporal variability of dryland aboveground primary production (ANPP and soil respiration. How the PPT legacy influences whole ecosystem-level carbon (C fluxes has rarely been quantitatively assessed, particularly at longer temporal scales. We parameterized a process-based ecosystem model to a semiarid savanna ecosystem in southwestern US, calibrated and evaluated the model performance based on 7 years of eddy covariance measurements, and conducted two sets of simulation experiments to assess interdecadal and interannual scale PPT legacy effects over a 30 year simulation period. The results showed that decreasing the previous period/year PPT (dry legacy always imposed positive impacts on net ecosystem production (NEP whereas increasing the previous period/year PPT (wet legacy had negative impacts on NEP. The simulated dry legacy impacts were mostly positive on gross ecosystem production (GEP and negative on ecosystem respiration (Re but the wet legacy impacts were mostly negative on GEP and positive on Re. Although the direction and magnitude of GEP and Re responses to the simulated dry and wet legacies were influenced by both the previous and current PPT conditions, the NEP responses were predominantly determined by the previous PPT characteristics including rainfall amount, seasonality and event size distribution. Larger PPT difference between periods/years resulted in larger legacy impacts, with dry legacies fostering more C sequestration and wet legacies more C release. By analyzing the resource pool (C, N, and H2O responses to the simulated dry and wet legacies, we found that the carryover of soil N between periods/years was mainly responsible for the GEP responses while the carryovers of plant biomass, litter and soil organic matter were mainly responsible for the Re

  7. A Contribution of Foreign Direct Investment, Clean Energy, Trade Openness, Carbon Emissions and Economic Growth to Energy Demand in UAE

    SBIA, Rashid; Shahbaz, Muhammad; Hamdi, Helmi

    2013-01-01

    This paper investigates the relationship between foreign direct investment, clean energy, trade openness, carbon emissions and economic growth in case of UAE covering the period of 1975Q1-2011Q4. We have tested the unit properties of variables in the presence of structural breaks. The ARDL bounds testing approach is applied to examine the cointegration by accommodating structural breaks stemming in the series. The VECM Granger causality approach is also applied to investigate the causal relat...

  8. Dual catalysis with magnetic chitosan: direct synthesis of cyclic carbonates from olefins with carbon dioxide using isobutyraldehyde as the sacrificial reductant.

    Kumar, Subodh; Singhal, Nikita; Singh, Raj K; Gupta, Piyush; Singh, Raghuvir; Jain, Suman L

    2015-07-14

    Chitosan coated magnetic nanoparticles were synthesized and used as a support for the immobilization of the cobalt(II) acetylacetonate complex [Co(acac)2] and quaternary triphenylphosphonium bromide [P(+)Ph3Br(-)] targeting -NH2 and -OH moieties located on the surface of chitosan. The synthesized material was used as a catalyst for one pot direct synthesis of cyclic carbonates from olefins via an oxidative carboxylation approach with carbon dioxide using isobutyraldehyde as the sacrificial reductant and molecular oxygen as the oxidant. After the reaction, the catalyst was recovered by applying an external magnet and reused for several runs without significant loss in catalytic activity and no leaching was observed during this course. PMID:26055991

  9. Dielectric constants of multiwall carbon nanotubes from direct current to microwave frequencies.

    Wang, Y C; Lue, J T; Pauw, K F

    2009-03-01

    A cylindrical rod constructed from a uniform mixture of multiwall carbon nanotubes and alumina powders dissolved in paraffin was inserted in the center of a radio frequency cavity. The real and imaginary dielectric constants of carbon tubes at various frequencies were measured, respectively, from the resonant frequencies and the quality factors, by a resistance-inductance-cacitance (RLC) meter and a microwave network analyzer. The dielectric rod benefits the protection of the sample from adsorbing moisture and preventing the rod from filling with air, thus making accurate measurments. A tunable probe specifically designed for the field pattern of a TM010 mode is delineated to improve the microwave coupling of the dielectric microwave resonator. This refined design is expected to facilitate the measurement yielding a significant manner. The real and imaginary parts of the dielectric constant of carbon nanotubes increase and decrease, respectively as frequencies increase satisfactorily in complying with the description from the free electron Drude model. PMID:19435033

  10. One-step hydrothermal synthesis of nitrogen-doped nanocarbons: albumine directing the carbonization of glucose.

    Baccile, Niki; Antonietti, Markus; Titirici, Maria-Magdalena

    2010-02-22

    We present a simple and green one-step pathway towards nitrogen-doped carbon nanostructures with controlled mesoporosity through hydrothermal treatment of glucose in the presence of model proteins. Performing the reaction with different amounts of egg white ovalbumin protein (OvA), carbonaceous nanoparticles or continuous nanosponges with high specific surface areas can be efficiently produced. The nitrogen content of the structures is rather high (up to 8 wt%) and can be kept constant up to 950 degrees C, while oxygen elimination and graphitization of the carbon material occurs. We demonstrate here that sustainable natural resources can be efficiently used in the synthesis of pure high-potential nanomaterials. PMID:19885901

  11. Direct synthesis of graphitic carbon nanostructures from saccharides and their use as electrocatalytic supports

    Sevilla Solís, Marta; Sanchís, C.; Valdés-Solís Iglesias, Teresa; E. Morallón; Fuertes Arias, Antonio Benito

    2008-01-01

    An easy method is described for fabricating graphitic carbon nanostructures (GCNs) from a variety of saccharides; i.e., a monosaccharide (glucose), a disaccharide (sucrose) and a polysaccharide (starch). The synthesis scheme consists of: (a) impregnation of saccharide with Ni or Fe nitrates, (b) heat treatment under inert atmosphere (N2) up to 900°C or 1000°C and (c) oxidation in liquid phase to selectively recover the graphitic carbon. This procedure leads to GCNs with a variety of morpholog...

  12. Polymer-Assisted Direct Deposition of Uniform Carbon Nanotube Bundle Networks for High Performance Transparent Electrodes

    Hellstrom, Sondra L.

    2009-06-23

    Flexible transparent electrodes are crucial for touch screen, flat panel display, and solar cell technologies. While carbon nanotube network electrodes show promise, characteristically poor dispersion properties have limited their practicality. We report that addition of small amounts of conjugated polymer to nanotube dispersions enables straightforward fabrication of uniform network electrodes by spin-coating and simultaneous tuning of parameters such as bundle size and density. After treatment in thionyl chloride, electrodes have sheet resistances competitive with other reported carbon nanotube based transparent electrodes to date. © 2009 American Chemical Society.

  13. Thin film transistors of single-walled carbon nanotubes grown directly on glass substrates

    We report a transistor of randomly networked single-walled carbon nanotubes on a glass substrate. The carbon nanotube networks acting as the active components of the thin film transistor were selectively formed on the transistor channel areas that were previously patterned with catalysts to avoid the etching process for isolating nanotubes. The nanotube density was more than 50 μm-2, which is much larger than the percolation threshold. Transistors were successfully fabricated with a conducting and transparent ZnO for the back-side gate and the top-side gate. This allows the transparent electronics or suggests thin film applications of nanotubes for future opto-electronics

  14. Polymer-assisted direct deposition of uniform carbon nanotube bundle networks for high performance transparent electrodes.

    Hellstrom, Sondra L; Lee, Hang Woo; Bao, Zhenan

    2009-06-23

    Flexible transparent electrodes are crucial for touch screen, flat panel display, and solar cell technologies. While carbon nanotube network electrodes show promise, characteristically poor dispersion properties have limited their practicality. We report that addition of small amounts of conjugated polymer to nanotube dispersions enables straightforward fabrication of uniform network electrodes by spin-coating and simultaneous tuning of parameters such as bundle size and density. After treatment in thionyl chloride, electrodes have sheet resistances competitive with other reported carbon nanotube based transparent electrodes to date. PMID:19422197

  15. CONVENTIONAL WATER TREATMENT AND DIRECT FILTRATION: TREATMENT AND REMOVAL OF TOTAL ORGANIC CARBON AND TRIHALOMETHANE PRECURSORS

    After describing the fundamentals of coagulation of humic substances for alum and cationic polyelectrolytes, field studies of two conventional-type water treatment plants are discussed. THM formation through the plants is examined, and removals of total organic carbon (TOC) and T...

  16. Pt-Ru electrocatalysts supported on ordered mesoporous carbon for direct methanol fuel cell

    Salgado, J.R.C.; Pastor, E. [Dpto de Quimica Fisica, Universidad de la Laguna, Avda. Astrofisico Francisco Sanchez, 38071 - La Laguna, Santa Cruz de Tenerife (Spain); Alcaide, F.; Alvarez, G. [Dpto de Energia, CIDETEC, P Miramon, 196, 20009 Donostia/San Sebastian (Spain); Calvillo, L.; Lazaro, M.J. [Instituto de Carboquimica, Miguel Luesma Castan 4, 50018, Zaragoza (Spain)

    2010-07-01

    Pt-Ru electrocatalysts supported on ordered mesoporous carbon (CMK-3) were prepared by the formic acid method. Catalysts were characterized applying energy dispersive X-ray analyses (EDX) and X-ray diffraction (XRD). Methanol and carbon monoxide oxidation was studied electrochemically by cyclic voltammetry, and current-time curves were recorded in a methanol solution in order to establish the activity towards this reaction under potentiostatic conditions. The physicochemical and electrochemical properties of the Pt-Ru catalysts supported on CMK-3 carbon were compared with those of electrocatalysts supported on Vulcan XC-72 and commercial catalyst from E-TEK. Additionally, in order to complete this study, Pt electrocatalysts supported on CMK-3 and Vulcan XC-72 were prepared by the same method and were used as reference. Results showed that the Pt-Ru/CMK-3 catalyst presented the best electrocatalytic activity towards the CO oxidation and, therefore, good perspectives to its application in DMFC anodes. On the other hand, the activity of the Pt-Ru/CMK-3 catalyst towards methanol oxidation was higher than that of the commercial Pt-Ru/C (E-TEK) catalyst on all examined potentials, confirming the potential of the bimetallic catalysts supported on mesoporous carbons. (author)

  17. Direct synthesis of carbon-templating mesoporous ZSM-5 using microwave heating

    Koo, J.-B.; Jiang, N.; Saravanamurugan, S.; Voláková, Martina; Musilová, Zuzana; Čejka, Jiří; Park, S.-E.

    2010-01-01

    Roč. 276, č. 2 (2010), s. 327-334. ISSN 0021-9517 Institutional research plan: CEZ:AV0Z40400503 Keywords : mesoporous ZSM-5 * template * microwave irradiation * carbon Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.415, year: 2010

  18. Robust direct effect of carbon dioxide on tropical circulation and regional precipitation

    Bony, Sandrine; Bellon, Gilles; Klocke, Daniel; Sherwood, Steven; Fermepin, Solange; Denvil, Sébastien

    2013-06-01

    Predicting the response of tropical rainfall to climate change remains a challenge. Rising concentrations of carbon dioxide are expected to affect the hydrological cycle through increases in global mean temperature and the water vapour content of the atmosphere. However, regional precipitation changes also closely depend on the atmospheric circulation, which is expected to weaken in a warmer world. Here, we assess the effect of a rise in atmospheric carbon dioxide concentrations on tropical circulation and precipitation by analysing results from a suite of simulations from multiple state-of-the-art climate models, and an operational numerical weather prediction model. In a scenario in which humans continue to use fossil fuels unabated, about half the tropical circulation change projected by the end of the twenty-first century, and consequently a large fraction of the regional precipitation change, is independent of global surface warming. Instead, these robust circulation and precipitation changes are a consequence of the weaker net radiative cooling of the atmosphere associated with higher atmospheric carbon dioxide levels, which affects the strength of atmospheric vertical motions. This implies that geo-engineering schemes aimed at reducing global warming without removing carbon dioxide from the atmosphere would fail to fully mitigate precipitation changes in the tropics. Strategies that may help constrain rainfall projections are suggested.

  19. Optical antenna arrays of carbon nanotubes and their fabrication on polyimide and transparent conducting oxides for direct device integration

    Wang, Y.; Kempa, K.; Kimball, B.; Ren, Z. F.

    2005-11-01

    Vertically-aligned carbon nanotubes/nanofibers grown on various substrates by a direct-current plasma-enhanced chemical vapor deposition method have been shown experimentally to function as classical low-loss dipole antenna arrays at optical frequencies. Two fundamental antenna effects, e.g., the polarization effect and length matching effect, directly observed on large-scale CNT arrays in visible frequency range, hold them promising for industry-level fabrication of devices including linear/beam-splitting polarizers, solar energy converters, THz demodulators, etc., some of which will, however, require or prefer a flexible and/or transparent conducting substrate to be compatible for multi-level integration and low-cost manufacturing process. A low-energy dark discharge fabrication technique is therefore devised which successfully yields CNT antennas directly on polyimide films and transparent conducting oxides (ITO, ZnO) with the absence of a buffer layer.

  20. The direct electrochemistry of glucose oxidase based on the synergic effect of amino acid ionic liquid and carbon nanotubes

    2009-01-01

    Amino acid ionic liquids(AAILs) have attracted much attention due to their special chemical and physical properties,especially their outstanding biocompatibility and truly green aspect.In this work,a novel electrochemical biosensing platform based on AAILs/carbon nanotubes(CNTs) composite was fabricated.AAILs were used as a novel solvent for glucose oxidase(GOD) and the GOD-AAILs/CNTs/GC electrode was conveniently prepared by immersing the carbon nanotubes(CNTs) modified glassy carbon(GC) electrode into AAILs containing GOD.The direct electrochemistry of GOD on the GOD-AAILs/CNTs/GC electrode has been investigated and a pair of reversible peaks was obtained by cyclic voltammetry.The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen.Due to the synergic effect of AAILs and CNTs,the GOD-AAILs/CNTs/GC electrode shows excellent electrocatalytic activity towards glucose with a linear range from 0.05 to 0.8 mM and a detection limit of 5.5 μM(S/N = 3).Furthermore,the biosensor exhibits good stability and ability to exclude the interference of commonly coexisting uric and ascorbic acid.Therefore,AAILs/CNTs composite can be a good candidate biocompatible material for the direct electrochemistry of the redox-active enzyme and the construction of third-generation enzyme sensors.

  1. The direct electrochemistry of glucose oxidase based on the synergic effect of amino acid ionic liquid and carbon nanotubes

    WANG MengDong; DENG ChunYan; NIE Zhou; XU XiaHong; YAO ShouZhuo

    2009-01-01

    Amino acid ionic liquids (AAILs) have attracted much attention due to their special chemical and physical properties,especially their outstanding biocompatibility and truly green aspect.In this work,a novel electrochemical biosensing platform based on AAILs/carbon nanotubes (CNTs) composite was fabricated.AAILs were used as a novel solvent for glucose oxidase (GOD) and the GOD-AAILs/CNTs/GC electrode was conveniently prepared by immersing the carbon nanotubes (CNTs) modified glassy carbon (GC) electrode into AAILs containing GOD.The direct electrochemistry of GOD on the GOD-AAILs/CNTs/GC electrode has been investigated and a pair of reversible peaks was obtained by cyclic voltammetry.The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen.Due to the synergic effect of AAILs and CNTs,the GOD-AAILs/CNTs/GC electrode shows excellent electrocatalytic activity towards glucose with a linear range from 0.05 to 0.8 mM and a detection limit of 5.5 μM (S/N=3).Furthermore,the biosensor exhibits good stability and ability to exclude the interference of commonly coexisting uric and ascorbic acid.Therefore,AAILs/CNTs composite can be a good candidate biocompatible material for the direct electrochemistry of the redox-active enzyme and the construction of third-generation enzyme sensors.

  2. Nano Ru Impregnated Ni-YSZ Anode as Carbon Resistance Layer for Direct Ethanol Solid Oxide Fuel Cells

    SUN Liangliang; ZHENG Tao; HU Zhimin; LUO Linghong; WU Yefan; XU Xu; CHENG Liang; SHI Jijun

    2015-01-01

    Carbon formation on conventional Ni and Y2O3stabilized zirconia (Ni/YSZ) anodes is a major problem for direct ethanol solid oxide fuel cells (DE-SOFC). A nanostructure Ru layer was grown in Ni/YSZ anodes through wet impregnation method with RuCl3solvent at pH=4. Anode-supported Ni-YSZ/YSZ/(La0.8Sr0.2)0.98MnO3±δ(LSM) and Ru-Ni-YSZ/YSZ/LSM fuel cells were compared in terms of the performance and carbon formation with ethanol fuel. X-ray diffraction, scanning electron microscopy,energy disperse spectroscopy and electrochemical workstation were used to study the morphology and fuel cell performance. The results indicate that a nano structured and pearl like Ru layer was well dispersed on the surface of Ni-YSZ materials. The single cell with Ru-impregnated Ni/YSZ showed a maximum power density of 369 mW/cmat 750°C, which was higher than Ni-YSZ/YSZ/LSM. Specifically, no carbon was formed in the anode after 1000 min operation. Fuel cell performance and carbon resistance were enhanced with the addition of the Ru layer.

  3. Insights into the effect of structure-directing agents on structural properties of mesoporous carbon for polymer electrolyte fuel cells

    A Arunchander; K G Nishanth; K K Tintula; S Gouse Peera; A K Sahu

    2015-04-01

    Synthesis of mesoporous carbon (MC) with well-defined morphologies and, wide range of surface area and pore size, is reported by organic–organic interaction between thermally decomposable surfactants (structure-directing agents) and the cost-effective carbon precursors, such as phloroglucinol and formaldehyde. Selected surfactants based on tri-block co-polymer, non-ionic and ionic, are used for synthesis of MCs with wide variation in their physical properties. The present method could be applied to large-scale production of porous carbon with desired surface area and pore morphology and would practically be relevant to many emerging technologies including electrochemical power sources such as super-capacitors and fuel cells. In the present study, we have successfully used MCs as gas-diffusion layers in fuel cell electrodes and established proper balance between air permeability and water management. The porous carbon contributes significantly to reduce mass transfer existing at high current density region resulting in improved performance of the polymer electrolyte fuel cells.

  4. A direct synthesis of mesoporous carbon supported MgO sorbent for CO{sub 2} capture

    Margandan Bhagiyalakshmi; Pushparaj Hemalatha; Mani Ganesh; Peng Mei Mei; Hyun Tae Jang [Hanseo University, Seosan (Republic of Korea). Chemical Engineering Department

    2011-04-15

    Ordered mesoporous carbon supported MgO (Mg-OMC) materials were synthesized by the carbonization of sulfuric-acid-treated silica/triblock copolymer/sucrose/Mg(NO{sub 3})2 composites. In the current approach, triblock copolymer P123 and sucrose were employed as both structure-directing agents for the self-assembly of rice husk ash silica solution and carbon precursor. Sulfuric acid was used to cross-link P123 and sucrose in the as-synthesized composites in order to improve the carbon yield. The synthesized Mg-OMC was characterized by X-ray diffraction, N{sub 2} adsorption-desorption isotherm method, X-ray photoelectron spectroscopy, scanning electron microscope equipped with energy dispersive X-ray analysis and transmission electron microscopy. The thermal stability of Mg-OMC was verified by CO{sub 2}-temperature programmed desorption, which confirmed the chemisorption of CO{sub 2} on MgO. The CO{sub 2} adsorption capacity of Mg-OMC-1 was observed to be 92 mg/g of sorbent which is comparable with that of the well established CO{sub 2} sorbents. 34 refs., 9 figs., 2 tabs.

  5. Direct electron transfer and electrocatalysis of glucose oxidase immobilized on glassy carbon electrode modified with Nafion and mesoporous carbon FDU-15

    In this paper, it was found that glucose oxidase (GOD) has been stably immobilized on glassy carbon electrode modified with mesoporous carbon FDU-15 (MC-FDU-15) and Nafion by simple technique. The sorption behavior of GOD immobilized on MC-FDU-15 matrix was characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis), FTIR, respectively, which demonstrated that MC-FDU-15 could facilitate the electron exchange between the active center of GOD and electrode. The direct electrochemistry and electrocatalysis behavior of GOD on the modified electrode were characterized by cyclic voltammogram (CV) which indicated that GOD immobilized on Nafion and MC-FDU-15 matrices display direct, reversible and surface-controlled redox reaction with an enhanced electron transfer rate constant of 4.095 s-1 in 0.1 M phosphate buffer solution (PBS) (pH 7.12). Furthermore, it was also discovered that, in the presence of O2, GOD immobilized on Nafion and MC-FDU-15 matrices could produce a linear response to glucose. Thus, Nafion/GOD-MC-FDU-15/GC electrode is hopeful to be used in glucose biosensor. In addition, GOD immobilized on MC-FDU-15 and Nafion matrices possesses an excellent bioelectrocatalytic activity for the reduction of O2. So, the Nafion/GOD-MC-FDU-15/GC electrode can be utilized as the cathode in biofuel cell.

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

    The GAC-SBR efficiency was decreased with the increase of dyestuff concentration or the decrease of bio-sludge concentration. The system showed the highest removal efficiency with synthetic textile wastewater (STWW) containing 40 mg/L direct red 23 or direct blue 201 under MLSS of 3000 mg/L and hydraulic retention time (HRT) of 7.5 days. But, the effluent NO3- was higher than that of the influent. Direct red 23 was more effective than direct blue 201 to repress the GAC-SBR system efficiency. The dyes removal efficiency of the system with STWW containing direct red 23 was reduced by 30% with the increase of direct red 23 from 40 mg/L to 160 mg/L. The system with raw textile wastewater (TWW) showed quite low BOD5 TKN and dye removal efficiencies of only 64.7 ± 4.9% and 50.2 ± 6.9%, respectively. But its' efficiencies could be increased by adding carbon sources (BOD5). The dye removal efficiency with TWW was increased by 30% and 20% by adding glucose (TWW + glucose) or Thai rice noodle wastewater (TWW + TRNWW), respectively. SRT of the systems were 28 ± 1 days and 31 ± 2 days with TWW + glucose and TWW + TRNWW, respectively

  7. Impact of direct greenhouse gas emissions on the carbon footprint of water reclamation processes employing nitrification–denitrification

    Schneider, Andrew G., E-mail: andrew.schneider@yale.edu [University of Cincinnati, Department of Geology, Cincinnati, OH 45221 (United States); Townsend-Small, Amy [University of Cincinnati, Department of Geology, Cincinnati, OH 45221 (United States); University of Cincinnati, Department of Geography, Cincinnati, OH 45221 (United States); Rosso, Diego [Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697-2175 (United States)

    2015-02-01

    Water reclamation has the potential to reduce water supply demands from aquifers and more energy-intensive water production methods (e.g., seawater desalination). However, water reclamation via biological nitrification–denitrification is also associated with the direct emission of the greenhouse gases (GHGs) CO{sub 2}, N{sub 2}O, and CH{sub 4}. We quantified these direct emissions from the nitrification–denitrification reactors of a water reclamation plant in Southern California, and measured the {sup 14}C content of the CO{sub 2} to distinguish between short- and long-lived carbon. The total emissions were 1.5 (± 0.2) g-fossil CO{sub 2} m{sup −3} of wastewater treated, 0.5 (± 0.1) g-CO{sub 2}-eq of CH{sub 4} m{sup −3}, and 1.8 (± 0.5) g-CO{sub 2}-eq of N{sub 2}O m{sup −3}, for a total of 3.9 (± 0.5) g-CO{sub 2}-eq m{sup −3}. This demonstrated that water reclamation can be a source of GHGs from long lived carbon, and thus a candidate for GHG reduction credit. From the {sup 14}C measurements, we found that between 11.4% and 15.1% of the CO{sub 2} directly emitted was derived from fossil sources, which challenges past assumptions that the direct CO{sub 2} emissions from water reclamation contain only modern carbon. A comparison of our direct emission measurements with estimates of indirect emissions from several water production methods, however, showed that the direct emissions from water reclamation constitute only a small fraction of the plant's total GHG footprint. - Highlights: • Direct greenhouse gas emissions were measured at a wastewater reclamation plant. • These greenhouse gas emissions amounted to 3.9 (± 0.5) g-CO{sub 2}-eq m{sup −3} of wastewater. • {sup 14}C analysis of the CO{sub 2} emissions was conducted to determine the fossil component. • 11.4% to 15.1% of the emitted CO{sub 2} was derived from fossil sources.

  8. Impact of direct greenhouse gas emissions on the carbon footprint of water reclamation processes employing nitrification–denitrification

    Water reclamation has the potential to reduce water supply demands from aquifers and more energy-intensive water production methods (e.g., seawater desalination). However, water reclamation via biological nitrification–denitrification is also associated with the direct emission of the greenhouse gases (GHGs) CO2, N2O, and CH4. We quantified these direct emissions from the nitrification–denitrification reactors of a water reclamation plant in Southern California, and measured the 14C content of the CO2 to distinguish between short- and long-lived carbon. The total emissions were 1.5 (± 0.2) g-fossil CO2 m−3 of wastewater treated, 0.5 (± 0.1) g-CO2-eq of CH4 m−3, and 1.8 (± 0.5) g-CO2-eq of N2O m−3, for a total of 3.9 (± 0.5) g-CO2-eq m−3. This demonstrated that water reclamation can be a source of GHGs from long lived carbon, and thus a candidate for GHG reduction credit. From the 14C measurements, we found that between 11.4% and 15.1% of the CO2 directly emitted was derived from fossil sources, which challenges past assumptions that the direct CO2 emissions from water reclamation contain only modern carbon. A comparison of our direct emission measurements with estimates of indirect emissions from several water production methods, however, showed that the direct emissions from water reclamation constitute only a small fraction of the plant's total GHG footprint. - Highlights: • Direct greenhouse gas emissions were measured at a wastewater reclamation plant. • These greenhouse gas emissions amounted to 3.9 (± 0.5) g-CO2-eq m−3 of wastewater. • 14C analysis of the CO2 emissions was conducted to determine the fossil component. • 11.4% to 15.1% of the emitted CO2 was derived from fossil sources

  9. Refractories for the direct production of low carbon stainless steel with niobium and molybdenum using the double slag technique

    The direct production of low carbon stainless steel with molybdenum and niobium was studied. Several basic crucibles with different compositions were analyzed to determine their resistance to wearing. The stainless steel was produced in an induction furnace from 1010 steel. The carbon content of the steel was lowered with briquettes containing iron oxide (scales) and lime introduced to the crucible. The first slag was removed and replaced by a second one formed only by pellets of lime; this second slag was removed before the addition of nickel and ferroalloys in the same crucible. The experimental results showed that the best resistance to wearing of the crucible was obtained with a mixture of 80% MAGNARMIX 363 and 20% Harmix Fe. (Author)

  10. Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments

    Peng, Jianfei; Hu, Min; Guo, Song; Du, Zhuofei; Zheng, Jing; Shang, Dongjie; Zamora, Misti Levy; Zeng, Limin; Shao, Min; Wu, Yu-Sheng; Zheng, Jun; Wang, Yuan; Glen, Crystal R.; Collins, Donald R.; Molina, Mario J.

    2016-01-01

    Black carbon (BC) exerts profound impacts on air quality and climate because of its high absorption cross-section over a broad range of electromagnetic spectra, but the current results on absorption enhancement of BC particles during atmospheric aging remain conflicting. Here, we quantified the aging and variation in the optical properties of BC particles under ambient conditions in Beijing, China, and Houston, United States, using a novel environmental chamber approach. BC aging exhibits two...

  11. High-temperature reactors for underground liquid-fuels production with direct carbon sequestration

    The world faces two major challenges: (1) reducing dependence on oil from unstable parts of the world and (2) minimizing greenhouse gas emissions. Oil provides 39% of the energy needs of the United States, and oil refineries consume over 7% of the total energy. The world is running out of light crude oil and is increasingly using heavier fossil feedstocks such as heavy oils, tar sands, oil shale, and coal for the production of liquid fuels (gasoline, diesel, and jet fuel). With heavier feedstocks, more energy is needed to convert the feedstocks into liquid fuels. In the extreme case of coal liquefaction, the energy consumed in the liquefaction process is almost twice the energy value of the liquid fuel. This trend implies large increases in carbon dioxide releases per liter of liquid transport fuel that is produced. It is proposed that high-temperature nuclear heat be used to refine hydrocarbon feedstocks (heavy oil, tar sands, oil shale, and coal) 'in situ ', i.e., underground. Using these resources for liquid fuel production would potentially enable the United States to become an exporter of oil while sequestering carbon from the refining process underground as carbon. This option has become potentially viable because of three technical developments: precision drilling, underground isolation of geological formations with freeze walls, and the understanding that the slow heating of heavy hydrocarbons (versus fast heating) increases the yield of light oils while producing a high-carbon solid residue. Required peak reactor temperatures are near 700 deg. C-temperatures within the current capabilities of high-temperature reactors. (authors)

  12. Directly-Grown Hierarchical Carbon Nanotube@Polypyrrole Core-Shell Hybrid for High-Performance Flexible Supercapacitors.

    Yesi, Yesi; Shown, Indrajit; Ganguly, Abhijit; Ngo, Trung Truc; Chen, Li-Chyong; Chen, Kuei-Hsien

    2016-02-19

    A hierarchical carbon nanotube-polypyrrole (CNT-PPy) core-shell composite was fabricated by growing CNTs directly on carbon cloth (CC) as a skeleton followed by electropolymerization of PPy with controlled polymerization time. Direct fabrication of electroactive (CNT-PPy) materials on the flexible CC electrode could reduce the interfacial resistance between the electrode and electrolyte and improve the ion diffusion. The supercapacitor electrode based on optimized PPy/CNT-CC exhibits excellent electrochemical performance, with the highest gravimetric capacitance being roughly 1038 F g(-1) per active mass of PPy and up to 486.1 F g(-1) per active mass of the PPy/CNT composite. Notably, excellent flexibility and cycle stability up to 10 000 cycles with only 18 % capacitance loss was achieved. At the same time, the fabricated asymmetric supercapacitor (PPy/CNT-CC∥CNT-CC) shows the maximum power density of 10 962 W kg(-1) at an energy density of 3.9 Wh kg(-1) under the operating potential of 1.4 V. The overall high cycle stability and high performance of the fabricated PPy/CNT-CC flexible electrode is due to the novel binder-free direct growth process. PMID:26791424

  13. Gold nanoparticles directly modified glassy carbon electrode for non-enzymatic detection of glucose

    Chang, Gang; Shu, Honghui; Ji, Kai [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); Oyama, Munetaka [Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8520 (Japan); Liu, Xiong [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); He, Yunbin, E-mail: ybhe@hubu.edu.cn [Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, Faculty of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China)

    2014-01-01

    This work describes controllable preparation of gold nanoparticles on glassy carbon electrodes by using the seed mediated growth method, which contains two steps, namely, nanoseeds attachment and nanocrystals growth. The size and the dispersion of gold nanoparticles grown on glassy carbon electrodes could be easily tuned through the growth time based on results of field-emission scanning electron microscopy. Excellent electrochemical catalytic characteristics for glucose oxidation were observed for the gold nanoparticles modified glassy carbon electrodes (AuNPs/GC), resulting from the extended active surface area provided by the dense gold nanoparticles attached. It exhibited a wide linear range from 0.1 mM to 25 mM with the sensitivity of 87.5 μA cm{sup −2} mM{sup −1} and low detection limit down to 0.05 mM for the sensing of glucose. The common interfering species such as chloride ion, ascorbic acid, uric acid and 4-acetamidophenol were verified having no interference effect on the detection of glucose. It is demonstrated that the seed mediated method is one of the facile approaches for fabricating Au nanoparticles modified substrates, which could work as one kind of promising electrode materials for the glucose nonenzymatic sensing.

  14. Final report : LDRD project 79824 carbon nanotube sorting via DNA-directed self-assembly.

    Robinson, David B; Leung, Kevin; Rempe, Susan B.; Dossa, Paul D.; Frischknecht, Amalie Lucile; Martin, Marcus Gary

    2007-10-01

    Single-wall carbon nanotubes (SWNTs) have shown great promise in novel applications in molecular electronics, biohazard detection, and composite materials. Commercially synthesized nanotubes exhibit a wide dispersion of geometries and conductivities, and tend to aggregate. Hence the key to using these materials is the ability to solubilize and sort carbon nanotubes according to their geometric/electronic properties. One of the most effective dispersants is single-stranded DNA (ssDNA), but there are many outstanding questions regarding the interaction between nucleic acids and SWNTs. In this work we focus on the interactions of SWNTs with single monomers of nucleic acids, as a first step to answering these outstanding questions. We use atomistic molecular dynamics simulations to calculate the binding energy of six different nucleotide monophosphates (NMPs) to a (6,0) single-wall carbon nanotube in aqueous solution. We find that the binding energies are generally favorable, of the order of a few kcal/mol. The binding energies of the different NMPs were very similar in salt solution, whereas we found a range of binding energies for NMPs in pure water. The binding energies are sensitive to the details of the association of the sodium ions with the phosphate groups and also to the average conformations of the nucleotides. We use electronic structure (Density Functional Theory (DFT) and Moller-Plesset second order perturbation to uncorrelated Hartree Fock theory (MP2)) methods to complement the classical force field study. With judicious choices of DFT exchange correlation functionals, we find that DFT, MP2, and classical force field predictions are in qualitative and even quantitative agreement; all three methods should give reliable and valid predictions. However, in one important case, the interactions between ions and metallic carbon nanotubes--the SWNT polarization-induced affinity for ions, neglected in most classical force field studies, is found to be extremely

  15. Removal of Direct Yellow-12 Dye from Water by Adsorption on Activated Carbon Prepared from Ficus Racemosa L.

    Revathi, G.; Ramalingam, S; P. Subramaniam; A. Ganapathi

    2011-01-01

    The adsorption of direct yellow-12 dye (DY-12) by Atti leaf (Ficus racemosa) powder carbon (ATC) was carried out by varying the parameters such as agitation time, dye concentration, adsorbent dose, pH and temperature. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. Adsorption followed second-order kinetics. The adsorption capacity was found to be 6.7 mg dye per gram of the adsorbent. Acidic pH was favorable for the adsorption of DY-12. Desorption studies suggest t...

  16. Zero emission power plants - a compatibility of the postcombustion technologies for the reduction of the Carbon emissions from thermal power plants with Directive 1996/61/EC

    An assessment of postcombustion- technologies for the reduction of the carbon emissions from thermal power plants with the Directive 1996/61/EC is done. It cannot be done quantitatively as in Bulgarian thermal power plants the carbon capture installations are not built. (authors)

  17. Effect of loading direction on crack growth behavior near fusion line in low carbon stainless steel weld joints

    SCC growth tests on the specimens machined out from SMAW and TIG weld joints of low carbon type 316L stainless steel were conducted in simulated BWR coolant condition to clarify effect of loading direction on SCC growth behavior near weld fusion line. The results obtained are as follows; (1) IGSCCs from pre-crack tips in base metal propagated toward the weld metal with branching of secondary cracks, and then, the cracks changed direction to avoid the weld metal and propagated along with the fusion line. Tendency of crack behavior of avoiding weld metal was observed remarkably in specimens, which had smaller angle between specimen neutral line and fusion line. (2) Propagation of large crack of IDSCC into weld metal was observed only in a specimen with the crack propagation direction vertical to the fusion line. (3) Result of crack length measurement for 63 secondary cracks, which propagated into weld metal showed that 80% of cracks located within 50 μm from the fusion line, and two cracks with propagation length greater than 150 μm were observed only in the specimens with the crack propagation direction vertical to the fusion line. These results suggested that SCC in the base metal tends to propagate to avoid the weld metal and the relationship between dendrite orientation and loading direction affects SCC propagation behavior into weld metal. (author)

  18. Direct evaluation of ballistic phonon transport in a multi-walled carbon nanotube

    Phonon confinement and in situ thermal conductance measurements in an individual multi-walled carbon nanotube (MWNT) are reported. Focused ion beam (FIB) irradiation was used to successively shorten a 4.8 μm long MWNT, eventually yielding a 0.3 μm long MWNT. After the first FIB irradiation, a 41% reduction in conductance was achieved, compared with that of the pristine MWNT. This was because the contributions from phonons with long free paths were excluded by scattering at FIB-induced defects. Phonon transport in linked multiple-length nanotubes was also investigated

  19. Direct asymmetric allylic alkenylation of N-itaconimides with Morita-Baylis-Hillman carbonates

    Yang, Wenguo

    2012-08-03

    The asymmetric allylic alkenylation of Morita-Baylis-Hillman (MBH) carbonates with N-itaconimides as nucleophiles has been developed using a commercially available Cinchona alkaloid catalyst. A variety of multifunctional chiral α-methylene-β-maleimide esters were attained in moderate to excellent yields (up to 99%) and good to excellent enantioselectivities (up to 91% ee). The origin of the regio- and stereoselectivity was verified by DFT methods. Calculated geometries and relative energies of various transition states strongly support the observed regio- and enantioselectivity. © 2012 American Chemical Society.

  20. Hybrid direct carbon fuel cell anode processes investigated using a 3-electrode half-cell setup

    Deleebeeck, Lisa; Arenillas, A.; Menendez, J.A.;

    2015-01-01

    anthracite and bituminous coals, as well as carbon black, were tested, revealing similar open circuit potential and activation energies in mixed 96-4vol% N2-CO2 and 50-50vol% CO-CO2 environments between 700 and 800°C. Bituminous coal showed the highest activity, likely associated to a high O/C ratio...... and hydrogen content. Based on acquired data, a reaction scheme was proposed for processes at the working electrode, including the role of bubble formation in the vicinity of the electrochemically active solid/molten medium interface....

  1. Supercritical carbon dioxide extracted oil from Jatropha curcas: directive for the biodiesel industry?

    Breet, Ernst Lodewyk Johannes; Van Greuning, Christien; Nortjé, Yolandi

    2011-01-01

    Jatropha curcas oil was extracted from seed by supercritical carbon dioxide (sc-CO2) and converted to a biodiesel in support of a world-wide search for a sustainable energy source produced by clean technology to replace rapidly dwindling fossil fuel resources. Analysis of the extracted oil by one-dimensional and two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GC × GC–TOFMS) before and after transesterification to fatty acid methyl esters (FAMEs) proved tha...

  2. Dynamic tensile stress–strain characteristics of carbon/epoxy laminated composites in through-thickness direction

    Nakai Kenji

    2015-01-01

    Full Text Available The effect of strain rate up to approximately ε̇ = 102/s on the tensile stress–strain properties of unidirectional and cross-ply carbon/epoxy laminated composites in the through-thickness direction is investigated. Waisted cylindrical specimens machined out of the laminated composites in the through-thickness direction are used in both static and dynamic tests. The dynamic tensile stress–strain curves up to fracture are determined using the split Hopkinson bar (SHB. The low and intermediate strain-rate tensile stress–strain relations up to fracture are measured on an Instron 5500R testing machine. It is demonstrated that the ultimate tensile strength and absorbed energy up to fracture increase significantly, while the fracture strain decreases slightly with increasing strain rate. Macro- and micro-scopic examinations reveal a marked difference in the fracture surfaces between the static and dynamic tension specimens.

  3. Novel nanometer-level uniform amorphous carbon coating for boron powders by direct pyrolysis of coronene without solvent

    A 3 nm coronene coating and a 4 nm amorphous carbon coating with a uniform shell–core encapsulation structure for nanosized boron (B) powders are formed by a simple process in which coronene is directly mixed with boron particles without a solvent and heated at 520 °C for 1 h or at 630 °C for 3 h in a vacuum-sealed silica tube. Coronene has a melting point lower than its decomposition temperature, which enables liquid coronene to cover B particles by liquid diffusion and penetration without the need for a solvent. The diffusion and penetration of coronene can extend to the boundaries of particles and to inside the agglomerated nanoparticles to form a complete shell–core encapsulated structure. As the temperature is increased, thermal decomposition of coronene on the B particles results in the formation of a uniform amorphous carbon coating layer. This novel and simple nanometer-level uniform amorphous carbon coating method can possibly be applied to many other powders; thus, it has potential applications in many fields at low cost. (paper)

  4. Direct electrochemistry of glucose oxidase and electrochemical biosensing of glucose on quantum dots/carbon nanotubes electrodes.

    Liu, Qing; Lu, Xianbo; Li, Jun; Yao, Xin; Li, Jinghong

    2007-06-15

    Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and carbon nanotubes (CNTs) are now extremely attractive and important nanomaterials in bioanalytical applications. In this work, CdTe QDs with the size of about 3 nm were prepared and a novel electrochemical biosensing platform of glucose based on CdTe/CNTs electrode was explored. This CdTe/CNTs electrode was prepared by first mixing CdTe QDs, CNTs, Nafion, and glucose oxidase (GOD) in appropriate amounts and then modifying this mixture on the glass carbon electrode (GC). Transmission electron microscopy (TEM) was used to observe the dispersion of CdTe QDs on carbon nanotubes and cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the CdTe/CNTs electrode. A pair of well-defined quasi-reversible redox peaks of glucose oxidase were obtained at the CdTe/CNTs based enzyme electrode by direct electron transfer between the protein and the electrode. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergy between the CdTe QDs and CNTs, this novel biosensing platform based on QDs/CNTs electrode responded even more sensitively than that based on GC electrode modified by CdTe QDs or CNTs alone. The inexpensive, reliable and sensitive sensing platform based on QDs/CNTs electrode provides wide potential applications in clinical, environmental, and food analysis. PMID:17416515

  5. Direct electron transfer of glucose oxidase promoted by carbon nanotubes is without value in certain mediator-free applications

    We have investigated the direct electron transfer (DET) promoted by carbon nanotubes (CNTs) on an electrode containing immobilized glucose oxidase (GOx) with the aim to develop a third-generation glucose biosensor and a mediator-free glucose biofuel cell anode. GOx was immobilized via chitosan (CS) on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs). Cyclic voltammetric revealed that the GOx on the surface of such an electrode is unable to simultaneously demonstrate DET with the electrode and to retain its catalytic activity towards glucose, although the MWCNTs alone can promote electron transfer between GOx and electrode. This is interpreted in terms of two types of GOx on the surface, the distribution and properties of which are quite different. The first type exhibits DET capability that results from the collaboration of MWCNTs and metal impurities, but is unable to catalyze the oxidation of glucose. The second type maintains its glucose-specific catalytic capability in the presence of a mediator, which can be enhanced by MWCNTs, but cannot undergo DET with the electrode. As a result, the MWCNTs are capable of promoting the electron transfer, but this is without value in some mediator-free applications such as in third-generation glucose biosensors and in mediator-free anodes for glucose biofuel cells. (author)

  6. Highly luminescent N, S- Co-doped carbon dots and their direct use as mercury(II) sensor

    Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg2+ complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg2+ is manufactured for the evaluation of usage of NSCDs in the real circumstance. - Highlights: • NSCDs were synthesized by using citric acid and rubeanic acid. • NSCDs exhibited an enhanced fluorescent efficiency with high QY up to 17.6%. • NSCDs presented good sensing performance to mercury ions. • NSCDs showed potential use as a multi-sensing platform

  7. Highly luminescent N, S- Co-doped carbon dots and their direct use as mercury(II) sensor

    Wang, Yu [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kim, Sung-Hoon, E-mail: shokim@knu.ac.kr [Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Feng, Liang, E-mail: fengl@dicp.ac.cn [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2015-08-26

    Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg{sup 2+} complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg{sup 2+} is manufactured for the evaluation of usage of NSCDs in the real circumstance. - Highlights: • NSCDs were synthesized by using citric acid and rubeanic acid. • NSCDs exhibited an enhanced fluorescent efficiency with high QY up to 17.6%. • NSCDs presented good sensing performance to mercury ions. • NSCDs showed potential use as a multi-sensing platform.

  8. Direct Electrochemistry of Hemoglobin Immobilized on a Functionalized Multi-Walled Carbon Nanotubes and Gold Nanoparticles Nanocomplex-Modified Glassy Carbon Electrode

    Nader Sheibani

    2013-07-01

    Full Text Available Direct electron transfer of hemoglobin (Hb was realized by immobilizing Hb on a carboxyl functionalized multi-walled carbon nanotubes (FMWCNTs and gold nanoparticles (AuNPs nanocomplex-modified glassy carbon electrode. The ultraviolet-visible absorption spectrometry (UV-Vis, transmission electron microscopy (TEM and Fourier transform infrared (FTIR methods were utilized for additional characterization of the AuNPs and FMWCNTs. The cyclic voltammogram of the modified electrode has a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.270 ± 0.002 V (vs. Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks was evaluated to be 4.0 ± 0.2 s−1. The average surface concentration of electro-active Hb on the surface of the modified glassy carbon electrode was calculated to be 6.8 ± 0.3 × 10−10 mol cm−2. The cathodic peak current of the modified electrode increased linearly with increasing concentration of hydrogen peroxide (from 0.05 nM to 1 nM with a detection limit of 0.05 ± 0.01 nM. The apparent Michaelis-Menten constant (Kmapp was calculated to be 0.85 ± 0.1 nM. Thus, the modified electrode could be applied as a third generation biosensor with high sensitivity, long-term stability and low detection limit.

  9. Direct synthesis of dimethyl carbonate from CO2 and methanol over CeO2 catalysts of different morphologies

    UNNIKRISHNAN P; SRINIVAS DARBHA

    2016-06-01

    The direct synthesis of dimethyl carbonate (DMC) from carbon dioxide CO2 and methanol is an attractive approach towards conversion of the greenhouse gas - CO2 into value-added chemicals and fuels.Ceria CeO2 catalyzes this reaction. But the conversion efficiency of CeO2 is enhanced when the byproductwater in the reaction medium is separated by employing trapping agents like 2-cyanopyridine (2-CP). In thiswork, the influence of morphology of CeO2 on the direct synthesis of DMC in presence of 2-CP is reported.CeO2 catalysts of cube, rod, spindle and irregular morphology (Ce - C, Ce - R, Ce - S and Ce - N, respectively)were prepared, characterized and studied as catalysts in the said reaction conducted in a batch mode. Amongall, Ce - S shows superior catalytic performance with nearly 100 mol% of DMC selectivity. Catalytic activitycorrelates with the concentration of acid and base sites of medium strength as well as defect sites. Ce - S has anoptimum number of these active sites and thereby shows superior catalytic performance.

  10. Direct electrochemistry and electrocatalysis of hemoglobin with carbon nanotube-ionic liquid-chitosan composite materials modified carbon ionic liquid electrode

    A novel composite biomaterial was prepared by combining chitosan, multi-walled carbon nanotubes (MWCNTs), hemoglobin (Hb) and ionic liquid (IL) 1-butyl-3-methyl-imidazolium bromide together, which was further modified on the surface of a carbon ionic liquid electrode (CILE) with another ionic liquid 1-ethyl-3-methylimidazolium ethylsulphate as the binder. Ultraviolet-visible and Fourier transform infrared spectroscopic results indicated that Hb molecules in the composite film retained the native structure. Cyclic voltammetric results showed that a pair of well-defined redox peaks appeared in 0.1 mol/L phosphate buffer solution, indicating that the direct electron transfer of Hb in the composite film with the underlying electrode was realized. The results were attributed to the synergistic effect of MWCNTs and IL in the composite film, which promoted the electron transfer rate of Hb. The composite material modified electrode showed excellent electrocatalytic ability towards the reduction of different substrates such as trichloroacetic acid and NaNO2 with good stability and reproducibility.

  11. Researching direct action against carbon emissions: a digital ethnography of climate agency

    Rebecca Pearse

    2010-10-01

    Full Text Available Global warming poses very directly the question of human agency. In this video ethnography of climate agency we explore dimensions of subjectivity in climate activism. Through a longitudinal study we track activist strategising as a reflexive process of creating climate agency. Activist reflection is presented as a balance between involvement and detachment, and analysed drawing on videoed interviews and on our own participation in organisations and events. Visual artefacts are deployed to deepen insights into the interview process, and into the contexts for climate action. In terms of the analysis, there are three themes. First we look at trajectories – how people come to identify with the climate movement and engage in its direct action wing. Second, we explore the hopes and fears of climate activists in the face of profound challenges. Third, we address political antidotes, and the role of direct action in precipitating large-scale systemic change. Across these themes there is much diversity and debate: what unifies is a common engagement in the broad field of direct climate action. This visual documentation helps us reflect on the conflicts and possibilities that thereby arise in contexts of climate activist praxis.

  12. Breakthroughs of Low-temperature Direct Rubber Mixing in Low-carbon Technology

    2011-01-01

    Rubber mixing is the most energy-consuming procedure in tire production, covering about 40% energy of the whole tire producing workflow. The process of low temperature direct rubber mixing, developed by Triangle Group Co., Ltd., MESNAC Co., Ltd., Yiyang Rubber and Plastics Co., Ltd., TTA (Qingdao) Tire Technology Co., Ltd., Guangzhou SCUT Bestry Technology Co., Ltd., etc.

  13. Thermo-mechanical characterization of epoxy nanocomposites with different carbon nanotube distributions obtained by solvent aided and direct mixing.

    M. Zarrelli

    2012-07-01

    Full Text Available Two different routes, namely solvent aided dispersion and direct mixing, were employed to disperse Multi-Walled Carbon Nanotubes (MWNTs into a mono-component epoxy system used as matrix for advanced composites. In the first route, MWCNTs were diluted in three different solvents (acetone, sodium dodecyl sulfate and ethanol and then mixed with the matrix by tip sonication. In the second case, carbonaceous nanoparticles were added directly into the hosting system and dispersion was carried out by using three different techniques (mechanical stirring, magnetic agitation and tip sonication. The effects of the solvents and agitation energy were investigated by optical microscopy at micron level, in order assess the more efficient dispersion procedure for the considered epoxy system. It was demonstrated that parameters associated with direct mixing rather than solvent solubility govern MWCNT dispersion. Optical analysis of the nanocomposite morphology evidenced a very low density of MWCNTs micron sized aggregates in the case of direct mixed tip sonicated samples if compared to those obtained by solution aided dispersion. In addition, nanocomposites obtained by sonication showed the lowest density of MWCNTs micron sized aggregates, also when compared with mechanically and magnetically stirred system. Dynamic Mechanical Analysis (DMA and Thermo-Mechanical Analysis (TMA results confirm the final result that among the considered direct mixing techniques, the direct tip sonication represents the most efficient route for MWCNT dispersion. Moreover, the mixing temperature of the hosting matrix system represents a fundamental feature in enhancing the MWCNT de-bundling and dispersion. Small X-ray Scattering analysis revealed that a nanosized structure of nanotubes is formed in the case of the tip sonicated samples that is heuristically correlated with both the maximum enhancement of mechanical modulus and the maximum reduction of thermal expansion coefficients.

  14. Direct and Highly Selective Conversion of Synthesis Gas into Lower Olefins: Design of a Bifunctional Catalyst Combining Methanol Synthesis and Carbon-Carbon Coupling.

    Cheng, Kang; Gu, Bang; Liu, Xiaoliang; Kang, Jincan; Zhang, Qinghong; Wang, Ye

    2016-04-01

    The direct synthesis of lower (C2 to C4 ) olefins, key building-block chemicals, from syngas (H2  /CO), which can be derived from various nonpetroleum carbon resources, is highly attractive, but the selectivity for lower olefins is low because of the limitation of the Anderson-Schulz-Flory distribution. We report that the coupling of methanol-synthesis and methanol-to-olefins reactions with a bifunctional catalyst can realize the direct conversion of syngas to lower olefins with exceptionally high selectivity. We demonstrate that the choice of two active components and the integration manner of the components are crucial to lower olefin selectivity. The combination of a Zr-Zn binary oxide, which alone shows higher selectivity for methanol and dimethyl ether even at 673 K, and SAPO-34 with decreased acidity offers around 70 % selectivity for C2 -C4 olefins at about 10 % CO conversion. The micro- to nanoscale proximity of the components favors the lower olefin selectivity. PMID:26961855

  15. Directional neurite growth using carbon nanotube patterned substrates as a biomimetic cue

    Researchers have made extensive efforts to mimic or reverse-engineer in vivo neural circuits using micropatterning technology. Various surface chemical cues or topographical structures have been proposed to design neuronal networks in vitro. In this paper, we propose a carbon nanotube (CNT)-based network engineering method which naturally mimics the structure of extracellular matrix (ECM). On CNT patterned substrates, poly-L-lysine (PLL) was coated, and E18 rat hippocampal neurons were cultured. In the early developmental stage, soma adhesion and neurite extension occurred in disregard of the surface CNT patterns. However, later the majority of neurites selectively grew along CNT patterns and extended further than other neurites that originally did not follow the patterns. Long-term cultured neuronal networks had a strong resemblance to the in vivo neural circuit structures. The selective guidance is possibly attributed to higher PLL adsorption on CNT patterns and the nanomesh structure of the CNT patterns. The results showed that CNT patterned substrates can be used as novel neuronal patterning substrates for in vitro neural engineering.

  16. Mechanism of direct current electrical charge conduction in p-toluenesulfonate doped polypyrrole/carbon composites

    Polypyrrole/carbon (PPy/C) composites have been synthesized using varying concentration of p-toluenesulfonate (pTS) dopant by surface initiated in-situ chemical oxidative polymerization. The synthesis and influence of pTS on the structure of the PPy/C composites are confirmed by Fourier transform infrared studies and the morphological features have been examined by scanning electron microscopy. X-ray photoelectron spectroscopy, employed to examine the surface composition and doping level of these composites, confirms the anionic doping into the polymer backbone. Electron spin resonance measurement has been carried out on these samples to identify the nature of the charge carriers and their concentration at different doping levels. The dc electrical conductivity of these composites has been measured in the temperature range ∼10–305 K. The observed results have been analyzed in the framework of existing theoretical models. Different Mott's parameters, such as characteristic temperature (T0), density of states at the Fermi level (N(EF)), average hopping distance (R), and average hopping energy (W), evaluated from dc conductivity data supports the applicability of Mott's three dimensional variable range hopping mechanism in this system

  17. Directed assembly of high density single-walled carbon nanotube patterns on flexible polymer substrates

    We report an effective technique for the controlled assembly of single-walled carbon nanotubes (SWNTs) and demonstrate organized high density network architectures on soft polymeric substrates. We utilize the surface energy differential between a plasma treated (hydrophilic) parylene-C surface and a photoresist (hydrophobic) surface to create microscale patterns of SWNT networks on a 10 μm thick parylene-C substrate. The large scale fabrication of patterned SWNT structures presented is achieved by performing site-selective fluidic assembly of SWNTs. Electrically continuous nanotube network micro-arrays as small as 4 μm wide that are up to 1500 μm long with controlled separation have been fabricated by dissolving the photoresist after assembly. Electrical and mechanical characterization of nanotube networks on the flexible substrate in both static and dynamic modes indicates that the structure can handle both compressive and tensile deformations with no hysteresis. The technology presented has immediate applications in making thin film transistors, interconnects and sensors on flexible substrates.

  18. Multi-Directional Growth of Aligned Carbon Nanotubes Over Catalyst Film Prepared by Atomic Layer Deposition

    Zhou Kai

    2010-01-01

    Full Text Available Abstract The structure of vertically aligned carbon nanotubes (CNTs severely depends on the properties of pre-prepared catalyst films. Aiming for the preparation of precisely controlled catalyst film, atomic layer deposition (ALD was employed to deposit uniform Fe2O3 film for the growth of CNT arrays on planar substrate surfaces as well as the curved ones. Iron acetylacetonate and ozone were introduced into the reactor alternately as precursors to realize the formation of catalyst films. By varying the deposition cycles, uniform and smooth Fe2O3 catalyst films with different thicknesses were obtained on Si/SiO2 substrate, which supported the growth of highly oriented few-walled CNT arrays. Utilizing the advantage of ALD process in coating non-planar surfaces, uniform catalyst films can also be successfully deposited onto quartz fibers. Aligned few-walled CNTs can be grafted on the quartz fibers, and they self-organized into a leaf-shaped structure due to the curved surface morphology. The growth of aligned CNTs on non-planar surfaces holds promise in constructing hierarchical CNT architectures in future.

  19. Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

    Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

    2011-01-01

    Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. PMID:20851447

  20. Direct Effect of Carbon Dioxide Concentration on Phytoplankton Community Structure in the Ross Sea, Antarctica

    Riesselman, C. R.; Tortell, P. D.; Payne, C. D.; Dunbar, R. B.; Ditullio, G. R.

    2006-12-01

    As the largest high-nutrient low-chlorophyll (HNLC) region on the planet, the Southern Ocean plays a critical role in global biogeochemical cycling and climate modulation. Primary productivity and phytoplankton community structure in the waters surrounding Antarctica have demonstrated unique sensitivity to small changes in major and trace element availability and vertical mixing. However, the capacity of changing atmospheric CO2 to restructure Antarctic phytoplankton communities has only recently been proposed. During the austral summer of 2005-2006, the "Controls on Ross Sea Algal Community Structure" (CORSACS) project performed an integrated series of shipboard incubations coupled with polynya water column sampling designed to investigate the interplay of iron, light, and CO2 levels as determinants of primary production and phytoplankton community structure. Results from the CORSACS CO2 manipulation incubation experiment demonstrate substantial shifts in the taxonomic distribution of phytoplankton exposed to an experimental CO2 gradient. Triplicate semi-continuous culture bottles were bubbled with air mixtures containing 100, 370, and 800 ppm CO2, designed to approximate bloom conditions under glacial, modern, and projected future levels of carbon dioxide. At the conclusion of the 18-day incubation, the 100 ppm community was dominated by the small, finely silicified pennate diatom Pseudonitzschia subcurvata, while the abundance of larger, colonial Chaetoceros species increased significantly in the 800 ppm community. These results represent the first evidence that perturbations in atmospheric CO2 have the potential to reorganize phytoplankton community structure in the Southern Ocean, and have implications for both the glacial productivity paradox and the future of polar trophic structure.

  1. Planar polyphthalocyanine cobalt absorbed on carbon black as stable electrocatalysts for direct methanol fuel cell

    Xu, Guofeng; Li, Zhongfang; Wang, Suwen; Yu, Xianjin [School of Chemical Engineering, Shandong University of Technology, 12 Zhangzhou Road, Zibo 255049, Shandong Province (China)

    2010-08-01

    In this work, a novel catalyst is prepared by dispersing planar polyphthalocyanine cobalt (PPcCo) synthesized by polymerizing cobalt (II)-4, 4',4'',4'''-phthalocyanine tetracarboxylic acid (TcPcCo) using a high surface area carbon powder (Vulcan XC 72), and then heat-treated in argon (Ar) atmosphere. The polymer and PPcCo/C catalysts are characterized systematically by a variety of methods, such as ultraviolet-visible (UV-vis) spectrophotometer, Fourier transform infrared spectrometer (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscope (TEM). Results show that the PPcCo obtained is stable below 600 C. The active site of PPcCo/C is CoN{sub 4} in phthalocyanine ring, and the PPcCo is dispersed homogeneously on the surface of XC 72. Electrocatalytic properties and electrochemical stability of the catalysts in 0.5 mol L{sup -1} H{sub 2}SO{sub 4} are evaluated by RDE measurements. The initial potential for O{sub 2} reduction in O{sub 2}-saturated H{sub 2}SO{sub 4} is 0.81 V and it catalyzed O{sub 2} reduction mainly through a four-electron process. Almost no performance degradation is observed over continuous cyclic voltammetry (CV) at 10,000 cycles (4 days). Polarization curves obtained by linear sweep voltammetry (LSV) at 200 cycles also show no change. PPcCo/C catalysts display significant electrocatalytic performance for O{sub 2} reduction, tolerance towards methanol, and long-term stability. (author)

  2. Orthogonal Experiments on Direct Reduction of Carbon-bearing Pellets of Bayer Red Mud

    Dun-cheng FAN; Wen NI; Ai-yun YAN; Jian-yue WANG; Wei-hua CUI

    2015-01-01

    To recycle residual iron efifciently in Bayer red mud, three-factor three-level orthogonal experiments on carbon-bearing pellets of Bayer red mud were conducted on the basis of their characteristics. The inlfuences of CaO dosage, temperature and roast-ing time on total iron content and iron recovery of reduced iron powder were studied. Results showed that these factors slightly inlfuenced iron recovery, but signiifcantly inlfuenced total iron content. The principal factor inlfuencing total iron content was CaO dosage, followed by temperature and roasting time. An increase in CaO dosage could decrease total iron content, whereas an increase in temperature and an extension of roasting time could improve total iron content. The reduced iron powder with total iron content of 88.41% and iron recovery rate of 97.97% can be obtained under the optimal conditions of temperature of 1 275 °C, roasting time of 60 min and CaO dosage of 7.5%. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses of the reduced pellets showed that iron minerals in red mud were almost completely reduced to metallic iron. The principal factor inlfuencing the total iron content of reduced iron powder was the grain size of metallic iron particles. An increase in CaO dosage hindered the growth of metallic iron particles, whereas an increase in temperature and an extension of roasting time could neutralise the effect of CaO dosage. Therefore, CaO dosage should be decreased when iron minerals in red mud can be adequately reduced into metallic iron.

  3. Photoluminescent carbon quantum dots as a directly film-forming phosphor towards white LEDs

    Zhang, Feng; Feng, Xiaoting; Zhang, Yi; Yan, Lingpeng; Yang, Yongzhen; Liu, Xuguang

    2016-04-01

    Photoluminescent organosilane-functionalized carbon quantum dots (CQDs), 3.0-3.5 nm in diameter, were synthesized via a facile hydrothermal method using citric acid monohydrate as a precursor and N-(3-(trimethoxysilyl) propyl) ethylenediamine as a coordinating and passivation agent. The optical properties of the as-obtained CQDs were investigated in detail. The CQD aqueous solution emits bright blue-white light under ultraviolet (UV) illumination with a quantum yield of 57.3% and high red-green-blue (RGB) spectral composition of 60.1%, and in particular the CQDs exhibit excitation-independent photoluminescence. The CQDs have a narrow size distribution around 3.1 nm and good film-forming ability through simple heat-treatment. By virtue of these excellent optical characteristics and good film-forming ability, a white light-emitting device (LED) was fabricated by combining a UV-LED chip with a single CQD phosphor film, which exhibited cool white light with a CIE coordinate of (0.31, 0.36), a color rendering index of 84 and a correlated color temperature of 6282 K. In addition, the white LED exhibits good optical stability under various working currents and for different working time intervals. Moreover, the interaction between the carbogenic core and surface groups was discussed using the DMol3 program based on density functional theory. This research suggests the great potential of CQDs for solid-state lighting systems and reveals the effect of the surface state on the photoluminescent mechanism of CQDs.

  4. Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production.

    Rau, Greg H; Carroll, Susan A; Bourcier, William L; Singleton, Michael J; Smith, Megan M; Aines, Roger D

    2013-06-18

    We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H2 production to effect significant air CO2 absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 10(5)-fold increase in OH(-) concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na2SO4 solutions when the anode was encased in powdered silicate mineral, either wollastonite or an ultramafic mineral. After electrolysis, full equilibration of the alkalized solution with air led to a significant pH reduction and as much as a 45-fold increase in dissolved inorganic carbon concentration. This demonstrated significant spontaneous air CO2 capture, chemical conversion, and storage as a bicarbonate, predominantly as NaHCO3. The excess OH(-) initially formed in these experiments apparently resulted via neutralization of the anolyte acid, H2SO4, by reaction with the base mineral silicate at the anode, producing mineral sulfate and silica. This allowed the NaOH, normally generated at the cathode, to go unneutralized and to accumulate in the bulk electrolyte, ultimately reacting with atmospheric CO2 to form dissolved bicarbonate. Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO2 captured), and inexpensive (<$100 per tonne of CO2 mitigated) removal of excess air CO2 with production of carbon-negative H2. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO2 emissions and in neutralizing or offsetting the effects of ongoing ocean acidification. PMID:23729814

  5. Direct electrochemistry of cytochrome c immobilized on titanium nitride/multi-walled carbon nanotube composite for amperometric nitrite biosensor.

    Haldorai, Yuvaraj; Hwang, Seung-Kyu; Gopalan, Anantha-Iyengar; Huh, Yun Suk; Han, Young-Kyu; Voit, Walter; Sai-Anand, Gopalan; Lee, Kwang-Pill

    2016-05-15

    In this report, titanium nitride (TiN) nanoparticles decorated multi-walled carbon nanotube (MWCNTs) nanocomposite is fabricated via a two-step process. These two steps involve the decoration of titanium dioxide nanoparticles onto the MWCNTs surface and a subsequent thermal nitridation. Transmission electron microscopy shows that TiN nanoparticles with a mean diameter of ≤ 20 nm are homogeneously dispersed onto the MWCNTs surface. Direct electrochemistry and electrocatalysis of cytochrome c immobilized on the MWCNTs-TiN composite modified on a glassy carbon electrode for nitrite sensing are investigated. Under optimum conditions, the current response is linear to its concentration from 1 µM to 2000 µM with a sensitivity of 121.5 µA µM(-1)cm(-2) and a low detection limit of 0.0014 µM. The proposed electrode shows good reproducibility and long-term stability. The applicability of the as-prepared biosensor is validated by the successful detection of nitrite in tap and sea water samples. PMID:26748372

  6. The Performance of Electron-Mediator Modified Activated Carbon as Anode for Direct Glucose Alkaline Fuel Cell

    Zi Li

    2016-06-01

    Full Text Available Six different electron mediators were immobilized on the activated carbon (AC anode and their effects on performance of a direct glucose alkaline fuel cell were explored. 2-hydroxy-1, 4-naphthoquinone (NQ, methyl viologen (MV, neutral red (NR, methylene blue (MB, 1, 5-dichloroanthraquinone (DA and anthraquinone (AQ were doped in activated carbon (AC, respectively, and pressed on nickel foam to fabricate the anodes. NQ shows comparable performance with MV, but with much lower cost and environmental impact. With NQ-AC anode, the fuel cell attained a peak power density of 16.10 Wm−2, peak current density of 48.09 Am−2, and open circuit voltage of 0.76 V under the condition of 1 M glucose, 3 M KOH, and ambient temperature. Polarization curve, EIS and Tafel measurements were also conducted to explore the mechanism of performance enhancement. The high performance is likely due to the enhanced charge transfer and more reactive sites provided on the anode.

  7. Nanoporous carbon supported platinum-copper nanocomposites as anode catalysts for direct borohydride-hydrogen peroxide fuel cell

    Highlights: • NPC supported Pt-Cu nanocomposites are used firstly as anode catalysts for DBHFC. • The average size of the Pt-Cu nanocrystals is around 2.3 nm. • The DBHFC with Pt2Cu/NPC anode shows the maximum power density of 89 mW cm−2. -- Abstract: Nanoporous carbon (NPC) supported Pt-Cu nanocomposites (PtxCu/NPC) with different Pt/Cu molar ratios have been successfully synthesized via NaBH4 reduction method and used as anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The as-synthesized PtxCu/NPC electrocatalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), cyclic voltammetry (CV), chronoamperometry (CA), rotating disc electrode (RDE) and fuel cell test. It has been found that the PtCu nanoparticles are uniformly dispersed on the surface of the NPC support with average size of about 2.3 nm. Besides, the PtxCu/NPC catalysts show higher activities for borohydride oxidation than that of monometallic Pt/NPC and Vulcan XC-72 carbon supported Pt2Cu (Pt2Cu/XC-72) catalysts. Especially, the DBHFC equipped with Pt2Cu/NPC as anode catalyst shows the maximum power density of 89 mW cm−2 at 25 °C

  8. Estimates of direct biological transport of radioactive waste in the deep sea with special reference to organic carbon budgets

    Calculations can be made for the maximum theoretical transport of pollutants such as radionuclides by movement of organisms out of a deep-sea benthic boundary layer dump site based on a presumption of a steady state organic carbon budget and estimated biological concentration factors. A calculated flux rate depends on the difference between a limiting input of organic matter and that carbon used by the biota or accumulating in the sediment. On average, the potential biological mass transport is low compared to physical transport. Exceptions to this generalization are possible in the far field after spatial gradients are obliterated or if natural mass migrations or periodic spawning concentrations occur in the near field. Biologically mediated fluxes of contaminants due to mixing of sediments by bioturbation or vertical flux due to scavenging by sinking particles are significant for movements of pollutants to and from sediments. These pathways contribute to the direct input of contaminants into food webs which may contain harvestable species. These fluxes are unimportant for mass transfers in the ocean but they determine the exposure of critical groups to contaminants

  9. Performance evaluation of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes

    The performance of direct borohydride–hydrogen peroxide fuel cells with electrocatalysts supported on multiwalled carbon nanotubes is evaluated under various conditions. Electrocatalysts are reduced on multiwalled carbon nanotubes by NaH2PO2 and electrodes are investigated using scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and fuel cell testing. The maximum power density decreases with increasing NaBH4 concentration, likely owing to increases in NaBH4 decomposition and crossover rates and to production of increasing amounts of NaBO2. In contrast, the maximum power density increases with increasing H2O2 concentration, likely owing to increases in reactant concentrations. Moreover, increased operating temperatures improve decomposition and electrochemical reaction rates. A thin membrane increases fuel crossover, whereas a thick membrane decreases the maximum power density; consequently, the Nafion 212 membrane is the optimal thickness for use in fuel cells such as those studied here. Under selected conditions, the maximum power density is 101.9 mW/cm2. As operation time increases, fuel cell performance is degraded by oxidation and Na deposition. - Highlights: • Maximum power density decreases as NaBH4 (sodium borohydride) concentration increases. • Maximum power density increases as H2O2 (hydrogen peroxide) concentration increases. • High operating temperatures cause fast electrochemical and decomposition reactions. • Nafion 212 is the most suitable membrane owing to its thickness. • Fuel cell performance decreases owing to oxidation and Na deposition

  10. Contribution of brown carbon and lensing to the direct radiative effect of carbonaceous aerosols from biomass and biofuel burning emissions

    Saleh, Rawad; Marks, Marguerite; Heo, Jinhyok; Adams, Peter J.; Donahue, Neil M.; Robinson, Allen L.

    2015-10-01

    We present global direct radiative effect (DRE) calculations of carbonaceous aerosols emitted from biomass/biofuel burning addressing the interplay between two poorly constrained contributions to DRE: mixing state of black carbon (lensing) and light absorption by organic aerosol (OA) due to the presence of brown carbon (BrC). We use the parameterization of Saleh et al. (2014) which captures the variability in biomass/biofuel OA absorption. The global mean effect of OA absorption is +0.22 W/m2 and +0.12 W/m2 for externally and internally mixed cases, while the effect of lensing is +0.39 W/m2 and +0.29 W/m2 for nonabsorbing and absorbing OA cases, signifying the nonlinear interplay between OA absorption and lensing. These two effects can be overestimated if not treated simultaneously in radiative transfer calculations. The combined effect of OA absorption and lensing increases the global mean DRE of biomass/biofuel aerosols from -0.46 W/m2 to +0.05 W/m2 and appears to reduce the gap between existing model-based and observationally constrained DRE estimates. We observed a strong sensitivity to these parameters in key regions, where DRE shifts from strongly negative ( +1 W/m2) when accounting for lensing and OA absorption.

  11. Carbon supported Cu-Pd nanoparticles as anode catalyst for direct borohydride-hydrogen peroxide fuel cells

    Carbon supported Cu-Pd bimetallic nanoparticles were prepared by a successive reduction method in aqueous solution and used as anode electrocatalyst for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), linear sweep voltammetry (LSV) and fuel cell test. The results show that the size of the crystallite is around 12.5 nm, the Cu1Pd1/C catalyst presents the highest catalytic activity among all the resultant catalysts, and the DBHFC using Cu1Pd1/C as anode catalyst and Pt mesh (1 cm × 1 cm) as cathode electrode obtains the maximum power density as high as 39.8 mW cm-2 at a discharge current density of 80.1 mA cm-2 at 20 °C

  12. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups

  13. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A., E-mail: jrogers@illinois.edu [Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Wahab, Muhammad A.; Alam, Muhammad A. [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Li, Yuhang [Institute of Solid Mechanics, Beihang University, Beijing 100191 (China); Tomic, Bojan [Department of Electrical Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Huang, Jiyuan [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Burns, Branden [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Song, Jizhou [Department of Engineering Mechanics and Soft Matter Research Center, Zhejiang University, Hangzhou 310027 (China); Huang, Yonggang [Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-04-07

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups.

  14. Removal of a hydrogenated amorphous carbon film from the tip of a micropipette electrode using direct current corona discharge.

    Kakuta, Naoto; Okuyama, Naoki; Yamada, Yukio

    2010-02-01

    Micropipette electrodes are fabricated by coating glass micropipettes first with metal and then with hydrogenated amorphous carbon (a-C:H) as an electrical insulator. Furthermore, at the tip of the micropipette electrode, the deposited a-C:H film needs to be removed to expose the metal-coated surface and hollow for the purposes of electrical measurement and injection. This paper describes a convenient and reliable method for removing the a-C:H film using direct current corona discharge in atmospheric air. The initial film removal occurred at an applied voltage of 1.5-2.0 kV, accompanied by an abrupt increase in the discharge current. The discharge current then became stable at a microampere level in the glow corona mode, and the removed area gradually extended. PMID:20192514

  15. Direct writing of carbon nanotube patterns by laser-induced chemical vapor deposition on a transparent substrate

    Dot array and line patterns of multi-walled carbon nanotubes (MWCNTs) were successfully grown by laser-induced chemical vapor deposition (LCVD) on a transparent substrate at room temperature. In the proposed technique, a Nd:YVO4 laser with a wavelength of 532 nm irradiates the backside of multiple catalyst layers (Ni/Al/Cr) through a transparent substrate to induce a local temperature rise, thereby allowing the direct writing of dense dot and line patterns of MWCNTs below 10 μm in size to be produced with uniform density on the controlled positions. In this LCVD method, a multiple-catalyst-layer with a Cr thermal layer is the central component for enabling the growth of dense MWCNTs with good spatial resolution.

  16. Effect of direct seeding mulch-based systems on soil carbon storage and macrofauna in central Brazil

    Blanchart, E.; Bernoux, M.; Sarda, X.; Feller, C. [Institut de Recherche pour le Developpement, Montpellier (France); Siqueira Neto, M.; Cerri, C.C.; Piccolo, M. [CENA-USP, Piracicaba (Brazil). Lab. Biogeoquimica Ambiental; Douzet, J.M. [CIRAD, Antsirabe (Madagascar); Scopel, E. [CIRAD-CA, Planaltina (Brazil)

    2007-07-01

    Soils represent a large carbon pool, approximately 1500 Gt, equivalent to almost three times the quantity stored in terrestrial biomass and twice the amount stored in the atmosphere. The management and maintenance of soil carbon is therefore an integral part of the global carbon cycle. Land use change, inappropriate agricultural practices and climate change can all lead to a net release of C from soils to the atmosphere, exacerbating the problems of greenhouse gas release. Any modification of land-use or land management can induce variations in soil carbon stocks, even in agricultural systems that are perceived to be in a steady state. These modifications also alter soil macrofauna that is known to affect soil carbon dynamics. Direct seeding Mulch-based Cropping (DMC) systems with two crops per year without soil tillage have widely been adopted over the last 10 to 15 years in the Cerrado (central region) of Brazil. They are replacing the traditional soybean monocropping with fallow under conventional tillage (CT). Th e objective of this study was to examine how DMC practices affect soil organic carbon (SOC) dynamics and macrofauna (Rio Verde, Goias State). The approach was to determine soil C stocks and macrofauna in five fi elds under DMC aged 1, 5, 7, 11 and 13 years. In order to compare DMC systems with the native system of the region and previous land-use, a situation under native Cerrado (tree-savanna like vegetation) and a field conducted traditionally (CT) were also studied. Soil C stocks were calculated for the 0-10 and 0-40 cm soil depth and also for the fi rst 400 kg m{sup -2} of soil to compare the same amount of soil and to suppress the potential artefact of soil compaction when sample is based on fix layer depth. Soil macrofauna was hand-sorted from soil monoliths (30 cm depth, TSBF method). In our study, the annual rate of carbon storage was equal to ca. 1.6 MgC ha{sup -1}, which is in the range of values measured for DMC in different areas of Brazil

  17. Direct observation of morphological evolution of a catalyst during carbon nanotube forest growth: new insights into growth and growth termination

    Jeong, Seojeong; Lee, Jaegeun; Kim, Hwan-Chul; Hwang, Jun Yeon; Ku, Bon-Cheol; Zakharov, Dmitri N.; Maruyama, Benji; Stach, Eric A.; Kim, Seung Min

    2016-01-01

    In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests.In this study, we develop a new methodology for transmission electron microscopy (TEM) analysis that enables us to directly investigate the interface between carbon nanotube (CNT) arrays and the catalyst and support layers for CNT forest growth without any damage induced by a post-growth TEM sample preparation. Using this methodology, we perform in situ and ex situ TEM investigations on the evolution of the morphology of the catalyst particles and observe the catalyst particles to climb up through CNT arrays during CNT forest growth. We speculate that the lifted catalysts significantly affect the growth and growth termination of CNT forests along with Ostwald ripening and sub-surface diffusion. Thus, we propose a modified growth termination model which better explains various phenomena related to the growth and growth termination of CNT forests. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05547d

  18. Production and Optimization of Direct Coal Liquefaction derived Low Carbon-Footprint Transportation Fuels

    Steven Markovich

    2010-06-30

    This report summarizes works conducted under DOE Contract No. DE-FC26-05NT42448. The work scope was divided into two categories - (a) experimental program to pretreat and refine a coal derived syncrude sample to meet transportation fuels requirements; (b) system analysis of a commercial scale direct coal liquefaction facility. The coal syncrude was derived from a bituminous coal by Headwaters CTL, while the refining study was carried out under a subcontract to Axens North America. The system analysis included H{sub 2} production cost via six different options, conceptual process design, utilities requirements, CO{sub 2} emission and overall plant economy. As part of the system analysis, impact of various H{sub 2} production options was evaluated. For consistence the comparison was carried out using the DOE H2A model. However, assumptions in the model were updated using Headwaters database. Results of Tier 2 jet fuel specifications evaluation by the Fuels & Energy Branch, US Air Force Research Laboratory (AFRL/RZPF) located at Wright Patterson Air Force Base (Ohio) are also discussed in this report.

  19. Solid-contact potentiometric aptasensor based on aptamer functionalized carbon nanotubes for the direct determination of proteins.

    Düzgün, Ali; Maroto, Alicia; Mairal, Teresa; O'Sullivan, Ciara; Rius, F Xavier

    2010-05-01

    A facile, solid-contact selective potentiometric aptasensor exploiting a network of single-walled carbon nanotubes (SWCNT) acting as a transducing element is described in this work. The molecular properties of the SWCNT surface have been modified by covalently linking aptamers as biorecognition elements to the carboxylic groups of the SWCNT walls. As a model system to demonstrate the generic application of the approach, a 15-mer thrombin aptamer interacts with thrombin and the affinity interaction gives rise to a direct potentiometric signal that can be easily recorded within 15 s. The dynamic linear range, with a sensitivity of 8.0 mV/log a(Thr) corresponds to the 10(-7)-10(-6) M range of thrombin concentrations, with a limit of detection of 80 nM. The aptasensor displays selectivity against elastase and bovine serum albumin and is easily regenerated by immersion in 2 M NaCl. The aptasensor demonstrates the capacity of direct detection of the recognition event avoiding the use of labels, mediators, or the addition of further reagents or analyte accumulation. PMID:20419254

  20. Potassium-doped carbon nanotubes toward the direct electrochemistry of cholesterol oxidase and its application in highly sensitive cholesterol biosensor

    Li Xiaorong [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xu Jingjuan, E-mail: xujj@nju.edu.cn [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen Hongyuan [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)

    2011-10-30

    We demonstrate herein a newly developed serum total cholesterol biosensor by using the direct electron transfer of cholesterol oxidase (ChOx), which is based on the immobilization of cholesterol oxidase and cholesterol esterase (ChEt) on potassium-doped multi-walled carbon nanotubes (KMWNTs) modified electrodes. The KMWNTs accelerate the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx and maintaining its bioactivity. As a new platform in cholesterol analysis, the resulting electrode (ChOx/KMWNTs/GCE) exhibits a sensitive response to free cholesterol, with a linear range of 0.050-16.0 {mu}mol L{sup -1} and a detection limit of 5.0 nmol L{sup -1} (S/N = 3). Coimmobilization of ChEt and ChOx (ChEt/ChOx/KMWNTs/GCE) allows the determination of both free cholesterol and esterified cholesterol. The resulting biosensor shows the same linear range of 0.050-16.0 {mu}mol L{sup -1} for free cholesterol and cholesteryl oleate, with the detection limit of 10.0 and 12.0 nmol L{sup -1} (S/N = 3), respectively. The concentrations of total (free and esterified) cholesterol in human serum samples, determined by using the techniques developed in the present study, are in good agreement with those determined by the well-established techniques using the spectrophotometry.

  1. The carbon assimilation network in Escherichia coli is densely connected and largely sign-determined by directions of metabolic fluxes.

    Valentina Baldazzi

    2010-06-01

    Full Text Available Gene regulatory networks consist of direct interactions but also include indirect interactions mediated by metabolites and signaling molecules. We describe how these indirect interactions can be derived from a model of the underlying biochemical reaction network, using weak time-scale assumptions in combination with sensitivity criteria from metabolic control analysis. We apply this approach to a model of the carbon assimilation network in Escherichia coli. Our results show that the derived gene regulatory network is densely connected, contrary to what is usually assumed. Moreover, the network is largely sign-determined, meaning that the signs of the indirect interactions are fixed by the flux directions of biochemical reactions, independently of specific parameter values and rate laws. An inversion of the fluxes following a change in growth conditions may affect the signs of the indirect interactions though. This leads to a feedback structure that is at the same time robust to changes in the kinetic properties of enzymes and that has the flexibility to accommodate radical changes in the environment.

  2. Direct electron transfer and biosensing of glucose oxidase immobilized at multiwalled carbon nanotube-alumina-coated silica modified electrode

    Investigations are reported regarding the direct electrochemical performance of glucose oxidase (GOD) immobilized on a film of multiwalled carbon nanotube-alumina-coated silica (MWCNT-ACS). The surface morphology of the GOD/MWCNT-ACS nanobiocomposite is characterized by scanning electron microscopy. In cyclic voltammetric response, the immobilized GOD displays a pair of well-defined redox peaks, with a formal potential (E°′) of − 0.466 V versus Ag/AgCl in a 0.1 M phosphate buffer solution (pH 7.5) at a scan rate of 0.05 V s−1; also the electrochemical response indicates a surface-controlled electrode process. The dependence of formal potential on solution pH indicates that the direct electron transfer reaction of GOD is a reversible two-electron coupled with a two-proton electrochemical reaction process. The glucose biosensor based on the GOD/MWCNT-ACS nanobiocomposite shows a sensitivity of 0.127 A M−1 cm−2 and an apparent Michaelis–Menten constant of 0.5 mM. Furthermore, the prepared biosensor exhibits excellent anti-interference ability to the commonly co-existed uric acid and ascorbic acid. - Highlights: ► A film composed of MWCNT-ACS was used for biosensor application. ► High sensitivity and good selectivity were obtained for the detection of glucose. ► This approach is potential for fabrication of mediator-free biosensor.

  3. Enzyme biosensor based on plasma-polymerized film-covered carbon nanotube layer grown directly on a flat substrate.

    Muguruma, Hitoshi; Hoshino, Tatsuya; Matsui, Yasunori

    2011-07-01

    We report a novel approach to fabrication of an amperometric biosensor with an enzyme, a plasma-polymerized film (PPF), and carbon nanotubes (CNTs). The CNTs were grown directly on an island-patterned Co/Ti/Cr layer on a glass substrate by microwave plasma enhanced chemical vapor deposition. The as-grown CNTs were subsequently treated by nitrogen plasma, which changed the surface from hydrophobic to hydrophilic in order to obtain an electrochemical contact between the CNTs and enzymes. A glucose oxidase (GOx) enzyme was then adsorbed onto the CNT surface and directly treated with acetonitrile plasma to overcoat the GOx layer with a PPF. This fabrication process provides a robust design of CNT-based enzyme biosensor, because of all processes are dry except the procedure for enzyme immobilization. The main novelty of the present methodology lies in the PPF and/or plasma processes. The optimized glucose biosensor revealed a high sensitivity of 38 μA mM(-1) cm(-2), a broad linear dynamic range of 0.25-19 mM (correlation coefficient of 0.994), selectivity toward an interferent (ascorbic acid), and a fast response time of 7 s. The background current was much smaller in magnitude than the current due to 10 mM glucose response. The low limit of detection was 34 μM (S/N = 3). All results strongly suggest that a plasma-polymerized process can provide a new platform for CNT-based biosensor design. PMID:21678995

  4. Alkaline direct ethanol fuel cell performance using alkali-impregnated polyvinyl alcohol/functionalized carbon nano-tube solid electrolytes

    Huang, Chien-Yi; Lin, Jia-Shiun; Pan, Wen-Han; Shih, Chao-Ming; Liu, Ying-Ling; Lue, Shingjiang Jessie

    2016-01-01

    This study investigates the application of a polyvinyl alcohol (PVA)/functionalized carbon nano-tubes (m-CNTs) composite in alkaline direct ethanol fuel cells (ADEFC). The m-CNTs are functionalized with PVA using the ozone mediation method, and the PVA composite containing the modified CNTs is prepared. Adding m-CNT into the PVA matrix enhances the alkaline uptake and the ionic conductivity of the KOH-doped electrolyte. Meanwhile, the m-CNT-containing membrane exhibited a lower swelling ratio and suppressed ethanol permeability compared to the pristine PVA film. The optimal condition for the ADEFC is determined to be under operation at an anode feed of 3 M ethanol in a 5 M KOH solution (at a flow rate of 5 cm3 min-1) with a cathode feed of moisturized oxygen (with a flow rate of 100 cm3 min-1) and the KOH-doped PVA/m-CNT electrolyte. We achieved a peak power density value of 65 mW cm-2 at 60 °C, which is the highest among the ADEFC literature data and several times higher than the proton-exchange direct ethanol fuel cells using sulfonated membrane electrolytes. Therefore, the KOH-doped PVA/m-CNT electrolyte is a suitable solid electrolyte for ADEFCs and has potential for commercialization in alkaline fuel cell applications.

  5. Synthesis of free-standing carbon nanohybrid by directly growing carbon nanotubes on air-sprayed graphene oxide paper and its application in supercapacitor

    Wei, Li; Jiang, Wenchao; Yuan, Yang; Goh, Kunli; Yu, Dingshan; Wang, Liang; Chen, Yuan

    2015-04-01

    We report the synthesis of a free-standing two dimensional carbon nanotube (CNT)-reduced graphene oxide (rGO) hybrid by directly growing CNTs on air-sprayed GO paper. As a result of the good integration between CNTs and thermally reduced GO film during chemical vapor deposition, excellent electrical conductivity (2.6×104 S/m), mechanical flexibility (electrical resistance only increases 1.1% after bent to 90° for 500 times) and a relatively large surface area (335.3 m2/g) are achieved. Two-electrode supercapacitor assembled using the CNT-rGO hybrids in ionic liquid electrolyte (1-ethyl-3-methylimidazolium tetrafluoroborate) shows excellent stability upon 500 bending cycles with the gravimetric energy density measuring 23.7 Wh/kg and a power density of 2.0 kW/kg. Furthermore, it shows an impedance phase angle of -64.4° at a frequency of 120 Hz, suggesting good potentials for 120 Hz alternating current line filtering applications.

  6. Direct Coupling of Cs2CO3 and Alcohols for the Synthesis of Dimethyl, Diethyl, and Various Dialkyl Carbonates

    An efficient and high-yield synthesis for DMC has been actively investigated. Reaction conditions typically involve either carbon monoxide (CO) or derivatives (e. g., phosgene), or carbon dioxide (CO2) or derivatives (e. g., inorganic carbonates or organic cyclic carbonates). Due to the toxicity and flammability of CO and phosgene, the more environmentally benign and sustainable carbon sources CO2 and derivatives have been actively employed for production of DMC and related acyclic carbonates. The DMC and acyclic carbonate syntheses that have been reported include: 1) transesterification of cyclic carbonates derived from oxirane and CO2; 2) dehydrative condensation of alcohols with CO2; 3) reactions between alkyl halide and metal carbonates; 4) reactions between alcohol, alkyl halide, and CO2; and 5) reactions between alcohol and CO2 in the presence of condensing agents

  7. Laccase on Black Pearl 2000 modified glassy carbon electrode: Characterization of direct electron transfer and biological sensing properties for pyrocatechol

    Highlights: ► Laccase can complete direct electron transfer process on BP2000 matrices. ► Laccase immobilized on BP2000 matrices has catalytic oxidation effect to pyrocatechol. ► A pyrocatechol biosensor has constructed been using Nafion/Lac-BP2000/GC electrode. ► Detection limit and linear range of the biosensor are 0.003 mM and 0.003–5.555 mM. - Abstract: In this paper, it was found that Laccase (Lac) could be stably immobilized on the glassy carbon electrode modified with Black Pearl 2000 (BP2000) and Nafion by a simple technique. The adsorption behavior of Lac immobilized on BP2000 matrix was characterized by environment scanning electron microscope (ESEM), ultraviolet–visible (UV–vis) and Fourier transform infrared (FTIR), which demonstrated that BP2000 could facilitate the electron exchange between the active center of Lac and modified electrode. The direct electrochemistry and electrocatalysis behavior of Lac on the modified electrode were characterized by cyclic voltammogram (CV) which indicated that Lac immobilized on the modified electrode displayed a direct, nearly reversible and surface-controlled redox reaction with an enhanced electron-transfer rate constant of 1.940 s−1 at the scan rate of 100 mV s−1 in 0.1 M phosphate buffer solution (PBS) (pH 7.0). Furthermore, it was also discovered that, in the presence of O2, Lac immobilized on the modified electrode exhibited the electrocatalytic response to pyrocatechol, and the kinetic apparent Michaelis-constant (KMapp) obtained from the Lineweaver–Burk equation was 1.79 mM. The detection limit, linear range and sensitivity of the Lac biosensor were 0.003 mM, 0.003–5.555 mM and 99.84 μA mM−1 cm−2, respectively.

  8. Exploiting simultaneous observational constraints on mass and absorption to estimate the global direct radiative forcing of black carbon and brown carbon

    X. Wang

    2014-06-01

    Full Text Available Atmospheric black carbon (BC is a leading climate warming agent, yet uncertainties on the global direct radiative forcing (DRF remain large. Here we expand a global model simulation (GEOS-Chem of BC to include the absorption enhancement associated with BC coating and separately treat both the aging and physical properties of fossil fuel and biomass burning BC. In addition we develop a global simulation of Brown Carbon (BrC from both secondary (aromatic and primary (biomass burning and biofuel sources. The global mean lifetime of BC in this simulation (4.4 days is substantially lower compared to the AeroCom I model means (7.3 days, and as a result, this model captures both the mass concentrations measured in near-source airborne field campaigns (ARCTAS, EUCAARI and surface sites within 30%, and in remote regions (HIPPO within a factor of two. We show that the new BC optical properties together with the inclusion of BrC reduces the model bias in Absorption Aerosol Optical Depth (AAOD at multiple wavelengths by more than 50% at AERONET sites worldwide. However our improved model still underestimates AAOD by a factor of 1.4 to 2.8 regionally, with largest underestimates in regions influenced by fire. Using the RRTMG model integrated with GEOS-Chem we estimate that the all-sky top-of-atmosphere DRF of BC is +0.13 W m−2 (0.08 W m−2 from anthropogenic sources and 0.05 W m−2 from biomass burning. If we scale our model to match AERONET AAOD observations we estimate the DRF of BC is +0.21 W m−2, with an additional +0.11 W m−2 of warming from BrC. Uncertainties in size, optical properties, observations, and emissions suggest an overall uncertainty in BC DRF of −80% / +140%. Our estimates are at the lower end of the 0.2–1.0 W m−2 range from previous studies, and substantially less than the +0.6 W m−2 DRF estimated in the IPCC 5th Assessment Report. We suggest that the DRF of BC has previously been overestimated due to the overestimation of

  9. 从超临界二氧化碳和甲醇直接合成碳酸二甲酯%DIRECT SYNTHESIS OF DIMETHYL CARBONATE FROM SUPERCRITICAL CARBON DIOXIDE AND METHANOL

    赵天生; 韩怡卓; 孙予罕; 杨彩虹; 李文彬

    1999-01-01

    @@ Dimethyl carbonate (DMC), an environmentally benign intermediate for organic synthesis, has been mainly synthesized through non-phosgene route of oxidative carbonylation[1]. Direct synthesis of DMC from carbon dioxide and methanol is of more significance due to atom economy. Organometallic compounds of formulae R2M(OR)2, M(OR)2 or M(OR)4[2,3] were employed as catalysts in direct synthesis of DMC, where an activation mechanism of CO2 insertion into metal-oxygen bond was supposed. Unfortunately, the yield of DMC was low even in the presence of chemical dehydrants because mainly of thermodynamic limit.

  10. Direct electron transfer and biosensing of glucose oxidase immobilized at multiwalled carbon nanotube-alumina-coated silica modified electrode

    Wu, Wei-Che; Huang, Jian-Lung; Tsai, Yu-Chen, E-mail: yctsai@dragon.nchu.edu.tw

    2012-05-01

    Investigations are reported regarding the direct electrochemical performance of glucose oxidase (GOD) immobilized on a film of multiwalled carbon nanotube-alumina-coated silica (MWCNT-ACS). The surface morphology of the GOD/MWCNT-ACS nanobiocomposite is characterized by scanning electron microscopy. In cyclic voltammetric response, the immobilized GOD displays a pair of well-defined redox peaks, with a formal potential (E Degree-Sign Prime ) of - 0.466 V versus Ag/AgCl in a 0.1 M phosphate buffer solution (pH 7.5) at a scan rate of 0.05 V s{sup -1}; also the electrochemical response indicates a surface-controlled electrode process. The dependence of formal potential on solution pH indicates that the direct electron transfer reaction of GOD is a reversible two-electron coupled with a two-proton electrochemical reaction process. The glucose biosensor based on the GOD/MWCNT-ACS nanobiocomposite shows a sensitivity of 0.127 A M{sup -1} cm{sup -2} and an apparent Michaelis-Menten constant of 0.5 mM. Furthermore, the prepared biosensor exhibits excellent anti-interference ability to the commonly co-existed uric acid and ascorbic acid. - Highlights: Black-Right-Pointing-Pointer A film composed of MWCNT-ACS was used for biosensor application. Black-Right-Pointing-Pointer High sensitivity and good selectivity were obtained for the detection of glucose. Black-Right-Pointing-Pointer This approach is potential for fabrication of mediator-free biosensor.

  11. Near-frictionless carbon coatings for spark-ignited direct-injected fuel systems. Final report, January 2002.; TOPICAL

    This report describes an investigation by the Tribology Section of Argonne National Laboratory (ANL) into the use of near-frictionless carbon (NFC) coatings for spark-ignited, direct-injected (SIDI) engine fuel systems. Direct injection is being pursued in order to improve fuel efficiency and enhance control over, and flexibility of, spark-ignited engines. SIDI technology is being investigated by the Partnership for a New Generation of Vehicles (PNGV) as one route towards meeting both efficiency goals and more stringent emissions standards. Friction and wear of fuel injector and pump parts were identified as issues impeding adoption of SIDI by the OTT workshop on ''Research Needs Related to CIDI and SIDI Fuel Systems'' and the resulting report, Research Needs Related to Fuel Injection Systems in CIDI and SIDI Engines. The following conclusions were reached: (1) Argonne's NFC coatings consistently reduced friction and wear in existing and reformulated gasolines. (2) Compared to three commercial DLC coatings, NFC provided the best friction reduction and protection from wear in gasoline and alternative fuels. (3) NFC was successfully deposited on production fuel injectors. (4) Customized wear tests were performed to simulate the operating environment of fuel injectors. (5) Industry standard lubricity test results were consistent with customized wear tests in showing the friction and wear reduction of NFC and the lubricity of fuels. (6) Failure of NFC coatings by tensile crack opening or spallation did not occur, and issues with adhesion to steel substrates were eliminated. (7) This work addressed several of the current research needs of the OAAT SIDI program, as defined by the OTT report Research Needs Related to Fuel Injection Systems in CIDI and SIDI Engines

  12. Regional energy efficiency, carbon emission performance and technology gaps in China: A meta-frontier non-radial directional distance function analysis

    At present, China is the largest primary energy consumer and carbon emitter in the world. Meantime, China is a large transitional economy with significant regional gaps. Against such backgrounds, the calculated results of energy and carbon performance indicators may be biased, without considering heterogeneity across regions. To this end, after incorporating region-heterogeneity, this paper provides detailed information, regarding energy efficiency, carbon emission performance and the potential of carbon emission reductions from regional perspectives, which may be important and useful for policy makers. Our main findings are as follows. Firstly, there is significant group-heterogeneity across regions in China, in terms of energy efficiency and carbon emission performance. Secondly, there are no considerable differences between total-factor and single-factor performance indices, since there is limited substitutability between energy inputs and other production inputs. Finally, significant carbon emission reductions can be made by “catching up” for regions with low energy efficiency and carbon emission performance. Looking ahead, the Chinese government should adopt measures to promote improvements in terms of energy efficiency and carbon emission performance in the short term. -- Highlights: •We adopt a meta-frontier non-radial directional distance function analysis. •We provide detailed information regarding energy and carbon emission performance. •We find that there is significant region-heterogeneity in China. •There are no large differences between total- and single-factor performance indices. •It can make great contributions to carbon emission reductions by “catching up”

  13. Nickel and cobalt electrodeposited on carbon fiber cloth as the anode of direct hydrogen peroxide fuel cell

    Yang, Fan; Cheng, Kui; Xiao, Xue; Yin, Jinling; Wang, Guiling; Cao, Dianxue

    2014-01-01

    Carbon fiber cloth (CFC) supported Ni and Co electrodes are prepared by electrodeposition (Ni/CFC and Co/CFC). Their catalytic performance for H2O2 electrooxidation in KOH solution is investigated and compared with Au/CFC electrode. Ni/CFC electrode exhibits higher catalytic activity than Au/CFC and Co/CFC electrodes. The performance of a direct peroxide-peroxide fuel cell (DPPFC) with Ni/CFC anode and Pd/CFC cathode is examined. The cell shows a peak power density of 21.6 mW cm-2 at 20 °C and 53.8 mW cm-2 at 50 °C. The cell performance is improved with the increase of anolyte and catholyte flow rate and operation temperature. Results indicates that the performance of DPPFC with low-cost Ni/CFC anodes is comparable with those using precious metal anodes, e.g., Au/CFC and Pd/CFC.

  14. Effect of the porous carbon layer in the cathode gas diffusion media on direct methanol fuel cell performances

    Park, Jun-Young [Department of Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea); Kim, Hee-Tak; Son, In-Hyuk; Han, Sangil [Energy Lab, Corporate R and D Center, Samsung SDI Co., LTD, 575, Shin-dong, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-391 (Korea); Lee, Eun Sook [Energy Research Center, Jinwoo Engineering, Co., LTD., 143-2, Gwelang-Ri, Jungnam-Myun, Hwasung-City, Kyunggi-Do 445-963 (Korea)

    2009-10-15

    The effect of cathode gas diffusion media with microporous layers (MPLs) on direct methanol fuel cell (DMFC) performances is studied by combining electrochemical analysis and physicochemical investigation. The membrane electrode assemblies (MEAs) using MPL-modified cathode gas diffusion layers (GDLs, GDL-1) showed slightly better performances (117 mW cm{sup -2}) at 0.4 V and 70 C than commercial GDL (SIGRACET {sup registered} product version: GDL-35BC, SGL Co.) DMFC MEAs (110 mW cm{sup -2}). This might be due to high gas permeability, uniform pore distributions, and low water transport coefficient including methanol crossover. For GDL-1, the air permeability was 31.0 cm{sup 3} cm{sup -2} s{sup -1}, while the one for SGL 35BC GDLs was 21.7 cm{sup 3} cm{sup -2} s{sup -1}. Also, the GDL-1 in the pore-size distribution diagrams had distinct peaks due to more uniform distributions of macropores and micropores with smaller holes between aggregates of carbon particles compared to GDL-35 BC as confirmed by SEM images. Furthermore, the MEA using GDL-1 for the cathode had a lower water transfer coefficient compared to an MEA with a commercial 35 BC GDL. (author)

  15. COx-Free Hydrogen and Carbon Nanofibers Produced from Direct Decomposition of Methane on Nickel-Based Catalysts

    Siang-Piao Chai; Sharif Hussein Sharif Zein; Abdul Rahman Mohamed

    2006-01-01

    Direct decomposition of methane was carried out using a fixed-bed reactor at 700 ℃ for the production of COx-free hydrogen and carbon nanofibers. The catalytic performance of NiO-M/SiO2catalysts (where M=AgO, CoO, CuO, FeO, MnOx and MoO) in methane decomposition was investigated.The experimental results indicate that among the tested catalysts, NiO/SiO2 promoted with CuO give the highest hydrogen yield. In addition, the examination of the most suitable catalyst support, including Al2O3, CeO2, La2O3, SiO2, and TiO2, shows that the decomposition of methane over NiO-CuO favors SiO2 support. Furthermore, the optimum ratio of NiO to CuO on SiO2 support for methane decomposition was determined. The experimental results show that the optimum weight ratio of NiO to CuO fell at 8:2(w/w) since the highest yield of hydrogen was obtained over this catalyst.

  16. Functionalized carbon nanotube-poly(arylene sulfone) composite membranes for direct methanol fuel cells with enhanced performance

    Joo, Sang Hoon; Pak, Chanho; Kim, Eun Ah; Lee, Yoon Hoi; Chang, Hyuk; Seung, Doyoung; Choi, Yeong Suk; Park, Jong-Bong; Kim, Tae Kyoung

    A new type of composite membrane, consisting of functionalized carbon nanotubes (CNTs) and sulfonated poly(arylene sulfone) (sPAS), is prepared for direct methanol fuel cell (DMFC) applications. The CNTs modified with sulfonic acid or PtRu nanopaticles are dispersed within the sPAS matrix by a solution casting method to afford SO 3CNT-sPAS or PtRu/CNT-sPAS composite membranes, respectively. Characterization of the composite membranes reveals that the functionalized CNTs are homogeneously distributed within the sPAS matrix and the composite membranes contain smaller ion clusters than the neat sPAS. The composite membranes exhibit enhanced mechanical properties in terms of tensile strength, strain and toughness, which leads to improvements in ion conductivity and methanol permeability compared with the neat sPAS membrane. In DMFC performance tests, the use of a PtRu/CNT-sPAS membrane yields high power density compared with the neat sPAS membrane, which demonstrates that the improved properties of the composite membranes induce an increase in power density. The strategy for CNT-sPAS composite membranes presented in this work can potentially be extended to other CNT-polymer composite systems.

  17. Direct measurement of charge transport through helical poly(ethyl propiolate) nanorods wired into gaps in single walled carbon nanotubes

    We report the direct measurement of electrical transport through rod-like polymer molecules, of poly(ethyl propiolate) (PEP), utilizing single walled carbon nanotubes (SWNTs) as electrodes. The electrical properties of the devices were measured (i) before cutting a SWNT, (ii) when a SWNT was cut and (iii) after PEP deposition into the nanoscale gap in a cut SWNT. The gate-dependent electrical properties showed a reduction in current from Ion = 2.4 x 10-7 A for SWNT devices to Ion = 3.6 x 10-9 A for PEP bridge devices, both with the ON/OFF ratio of 104. Similarly, metallic SWNT devices showed a reduction in current from a few hundreds of μA for a SWNT device to a few nA for a PEP-SWNT structure. The current density of a single PEP molecule is 105-106 A cm-2, which is relatively high, indicating that the PEP molecule can carry significant current. Use of SWNT electrodes was seen to be an effective method of contacting PEP nanorods to facilitate electrical measurements.

  18. Direct Electrochemistry and Electrocatalysis of Myoglobin with CoMoO4 Nanorods Modified Carbon Ionic Liquid Electrode

    By using ionic liquid 1-hexylpyridinium hexafluorophosphate (HPPF6) based carbon ionic liquid electrode (CILE) as the substrate electrode, a CoMoO4 nanorods and myoglobin (Mb) composite was casted on the surface of CILE with chitosan (CTS) as the film forming material to obtain the modified electrode (CTS/CoMoO4-Mb/CILE). Spectroscopic results indicated that Mb retained its native structures without any conformational changes after mixed with CoMoO4 nanorods and CTS. Electrochemical behaviors of Mb on the electrode were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks from the heme Fe(III)/Fe(II) redox center of Mb appeared, which indicated that direct electron transfer between Mb and CILE was realized. Electrochemical parameters such as the electron transfer number (n), charge transfer coefficient (α) and electron transfer rate constant (ks) were estimated by cyclic voltammetry with the results as 1.09, 0.53 and 1.16 s-1, respectively. The Mb modified electrode showed good electrocatalytic ability toward the reduction of trichloroacetic acid in the concentration range from 0.1 to 32.0 mmol L-1 with the detection limit as 0.036 mmol L-1 (3σ), and the reduction of H2O2 in the concentration range from 0.12 to 397.0 μmol L-1 with the detection limit as 0.0426 μmol L-1 (3σ)

  19. Highly conductive single-walled carbon nanotube thin film preparation by direct alignment on substrates from water dispersions.

    Azoz, Seyla; Exarhos, Annemarie L; Marquez, Analisse; Gilbertson, Leanne M; Nejati, Siamak; Cha, Judy J; Zimmerman, Julie B; Kikkawa, James M; Pfefferle, Lisa D

    2015-01-27

    A safe, scalable method for producing highly conductive aligned films of single-walled carbon nanotubes (SWNTs) from water suspensions is presented. While microfluidic assembly of SWNTs has received significant attention, achieving desirable SWNT dispersion and morphology in fluids without an insulating surfactant or toxic superacid is challenging. We present a method that uniquely produces a noncorrosive ink that can be directly applied to a device in situ, which is different from previous fabrication techniques. Functionalized SWNTs (f-SWNTs) are dispersed in an aqueous urea solution to leverage binding between the amine group of urea and the carboxylic acid group of f-SWNTs and obtain urea-SWNT. Compared with SWNTs dispersed using conventional methods (e.g., superacid and surfactants), the dispersed urea-SWNT aggregates have a higher aspect ratio with a rodlike morphology as measured by light scattering. The Mayer rod technique is used to prepare urea-SWNT, highly aligned films (two-dimensional nematic order parameter of 0.6, 5 μm spot size, via polarized Raman) with resistance values as low as 15-1700 Ω/sq in a transmittance range of 2-80% at 550 nm. These values compete with the best literature values for conductivity of SWNT-enabled thin films. The findings offer promising opportunities for industrial applications relying on highly conductive thin SWNT films. PMID:25547120

  20. Ru-decorated Pt nanoparticles on N-doped multi-walled carbon nanotubes by atomic layer deposition for direct methanol fuel cells

    Johansson, Anne-Charlotte Elisabeth Birgitta; Yang, R.B.; Haugshøj, K.B.;

    2013-01-01

    We present atomic layer deposition (ALD) as a new method for the preparation of highly dispersed Ru-decorated Pt nanoparticles for use as catalyst in direct methanol fuel cells (DMFCs). The nanoparticles were deposited onto N-doped multi-walled carbon nanotubes (MWCNTs) at 250 °C using trimethyl...... controlled size and composition can be deposited, with up-scaling prospects....

  1. A novel method of carbon dioxide clumped isotope analysis with tunable infra-red laser direct absorption spectroscopy

    Prokhorov, Ivan; Kluge, Tobias; Janssen, Christof

    2016-04-01

    Precise clumped isotopes analysis of carbon dioxide opens up new horizons of atmospheric and biogeochemical research. Recent advances in laser and spectroscopic techniques provides us necessary instrumentation to access extremely low sub-permill variations of multiply-substituted isotopologues. We present an advanced analysis method of carbon dioxide clumped isotopes using direct absorption spectroscopy. Our assessments predict the ultimate precision of the new method on the sub-permill level comparable to state of the art mass spectrometry. Among the most auspicious intrinsic properties of this method we highlight genuine Δ16O13C18O and Δ16O13C18O measurements without isobaric interference, measurement cycle duration of several minutes versus hours for mass spectrometric analysis, reduced sample size of ˜ 10 μmol and high flexibility, allowing us to perform in-situ measurements. The pilot version of the instrument is being developed in an international collaboration framework between Heidelberg University, Germany and Pierre and Marie Curie University, Paris, France. It employs two continuous interband quantum cascade lasers tuned at 4.439 μm and 4.329 μm to measure doubly ( 16O13C18O, 16O13C17O) and singly ( 16O12C16O, 16O13C16O, 16O12C17O, 16O12C18O) substituted isotopologues, respectively. Two identical Herriot cells are filled with dry pure CO2 sample and reference gas at working pressure of 1 ‑ 10 mbar. Cells provide optical path lengths of ˜ 17 m for the laser tuned at doubly substituted isotopologues lines and use a single pass for the laser tuned at the stronger lines of singly substituted isotopologues. Light outside of the gas cells is coupled into optical fiber to avoid absorption by ambient air CO2. Simulations predict sub-permill precision at working pressure of 1 mbar and room temperature stabilised at the ±10 mK level. Our prime target is to apply the proposed method for continuous in-situ analysis of CO2. We are foreseeing potential

  2. Carbon Nanotube Emissions from Arc Discharge Production: Classification of Particle Types with Electron Microscopy and Comparison with Direct Reading Techniques

    Ludvigsson, Linus; Isaxon, Christina; Nilsson, Patrik T.; Tinnerberg, Hakan; Messing, Maria E.; Rissler, Jenny; Skaug, Vidar; Gudmundsson, Anders; Bohgard, Mats; Hedmer, Maria; Pagels, Joakim

    2016-01-01

    Introduction: An increased production and use of carbon nanotubes (CNTs) is occurring worldwide. In parallel, a growing concern is emerging on the adverse effects the unintentional inhalation of CNTs can have on humans. There is currently a debate regarding which exposure metrics and measurement strategies are the most relevant to investigate workplace exposures to CNTs. This study investigated workplace CNT emissions using a combination of time-integrated filter sampling for scanning electron microscopy (SEM) and direct reading aerosol instruments (DRIs). Material and Methods: Field measurements were performed during small-scale manufacturing of multiwalled carbon nanotubes using the arc discharge technique. Measurements with highly time- and size-resolved DRI techniques were carried out both in the emission and background (far-field) zones. Novel classifications and counting criteria were set up for the SEM method. Three classes of CNT-containing particles were defined: type 1: particles with aspect ratio length:width >3:1 (fibrous particles); type 2: particles without fibre characteristics but with high CNT content; and type 3: particles with visible embedded CNTs. Results: Offline sampling using SEM showed emissions of CNT-containing particles in 5 out of 11 work tasks. The particles were classified into the three classes, of which type 1, fibrous CNT particles contributed 37%. The concentration of all CNT-containing particles and the occurrence of the particle classes varied strongly between work tasks. Based on the emission measurements, it was assessed that more than 85% of the exposure originated from open handling of CNT powder during the Sieving, mechanical work-up, and packaging work task. The DRI measurements provided complementary information, which combined with SEM provided information on: (i) the background adjusted emission concentration from each work task in different particle size ranges, (ii) identification of the key procedures in each work

  3. Fundamental Discovery of New Phases and Direct Conversion of Carbon into Diamond and hBN into cBN and Properties

    Narayan, Jagdish; Bhaumik, Anagh

    2016-04-01

    We review the discovery of new phases of carbon (Q-carbon) and BN (Q-BN) and address critical issues related to direct conversion of carbon into diamond and hBN into cBN at ambient temperatures and pressures in air without any need for catalyst and the presence of hydrogen. The Q-carbon and Q-BN are formed as a result of quenching from super undercooled state by using high-power nanosecond laser pulses. We discuss the equilibrium phase diagram ( P vs T) of carbon, and show that by rapid quenching, kinetics can shift thermodynamic graphite/diamond/liquid carbon triple point from 5000 K/12 GPa to super undercooled carbon at atmospheric pressure in air. Similarly, the hBN-cBN-Liquid triple point is shifted from 3500 K/9.5 GPa to as low as 2800 K and atmospheric pressure. It is shown that nanosecond laser heating of amorphous carbon and nanocrystalline BN on sapphire, glass, and polymer substrates can be confined to melt in a super undercooled state. By quenching this super undercooled state, we have created a new state of carbon (Q-carbon) and BN (Q-BN) from which nanocrystals, microcrystals, nanoneedles, microneedles, and thin films are formed depending upon the nucleation and growth times allowed and the presence of growth template. The large-area epitaxial diamond and cBN films are formed, when appropriate planar matching or lattice matching template is provided for growth from super undercooled liquid. The Q-phases have unique atomic structure and bonding characteristics as determined by high-resolution SEM and backscatter diffraction, HRTEM, STEM-Z, EELS, and Raman spectroscopy, and exhibit new and improved mechanical hardness, electrical conductivity, and chemical and physical properties, including room-temperature ferromagnetism and enhanced field emission. The Q-carbon exhibits robust bulk ferromagnetism with estimated Curie temperature of about 500 K and saturation magnetization value of 20 emu g-1. We have also deposited diamond on cBN by using a novel

  4. Microwave-assisted synthesis of high-loading, highly dispersed Pt/carbon aerogel catalyst for direct methanol fuel cell

    Zhijun Guo; Hong Zhu; Xinwei Zhang; Fanghui Wang; Yubao Guo; Yongsheng Wei

    2011-06-01

    A Pt supported on carbon aerogel catalyst has been synthesized by the microwave-assisted polyol process. The Pt supported on carbon aerogel catalyst was characterized by high resolution transmission electron microscopy and X-ray diffraction. The results show a uniform dispersion of spherical Pt nanoparticles 2.5–3.0 nm in diameter. Cyclic voltammetry and chronoamperometry were used to evaluate the electrocatalytic activity of the Pt/carbon aerogel catalyst for methanol oxidation at room temperature. The Pt/carbon aerogel catalyst shows higher electrochemical catalytic activity and stability for methanol oxidation than a commercial Pt/C catalyst of the same Pt loading.

  5. Measuring the Total-Factor Carbon Emission Performance of Industrial Land Use in China Based on the Global Directional Distance Function and Non-Radial Luenberger Productivity Index

    Wei Wang

    2016-04-01

    Full Text Available Industry is a major contributor to carbon emissions in China, and industrial land is an important input to industrial production. Therefore, a detailed analysis of the carbon emission performance of industrial land use is necessary for making reasonable carbon reduction policies that promote the sustainable use of industrial land. This paper aims to analyze the dynamic changes in the total-factor carbon emission performance of industrial land use (TCPIL in China by applying a global directional distance function (DDF and non-radial Luenberger productivity index. The empirical results show that the eastern region enjoys better TCPIL than the central and western regions, but the regional gaps in TCPIL are narrowing. The growth in NLCPILs (non-radial Luenberger carbon emission performance of industrial land use in the eastern and central regions is mainly driven by technological progress, whereas efficiency improvements contribute more to the growth of NLCPIL in the western region. The provinces in the eastern region have the most innovative and environmentally-friendly production technologies. The results of the analysis of the influencing factors show implications for improving the NLCPIL, including more investment in industrial research and development (R&D, the implementation of carbon emission reduction policies, reduction in the use of fossil energy, especially coal, in the process of industrial production, actively learning about foreign advanced technology, properly solving the problem of surplus labor in industry and the expansion of industrial development.

  6. A Two-Dimensional Extremely Short Optical Pulse in a System of Carbon Nanotubes in a Direct Current Electric Field

    Belonenko, M. B.; Galkina, E. N.; Filimonova, Z. A.

    2016-03-01

    The effect of an external dc electric field on the two-dimensional extremely short optical pulse propagating in a zigzag carbon nanotube array was investigated. The electromagnetic field evolution in the investigated nanotube system is described by the Maxwell equations. Using numerical simulation, the interaction between the pulse electromagnetic field and the external electric field applied to the carbon nanotube array is analyzed.

  7. MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

    G. AGARWAL

    2014-10-01

    Full Text Available This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to represent the behaviour of composite structures with that of fiber loading. Thermo-mechanical properties of the material are measured with the help of Dynamic Mechanical Analyser to measure the damping capacity of the material that is used to reduce the vibrations. The effect of storage modulus, loss modulus and tan delta with temperature are determined. Finally, Cole–Cole analysis is performed on both bidirectional and short carbon fiber reinforced epoxy composites to distinguish the material properties of either homogeneous or heterogeneous materials. The results show that with the increase in fiber loading the mechanical properties of bidirectional carbon fiber reinforced epoxy composites increases as compared to short carbon fiber reinforced epoxy composites except in case of hardness, short carbon fiber reinforced composites shows better results. Similarly, as far as Loss modulus, storage modulus is concerned bidirectional carbon fiber shows better damping behaviour than short carbon fiber reinforced composites.

  8. Direct synthesis of dimethyl carbonate and propylene glycol using potassium bicarbonate as catalyst in supercritical CO2

    Wen Yicun

    2015-03-01

    Full Text Available The improved one-pot synthesis of dimethyl carbonate and propylene glycol from propylene oxide, supercritical carbon dioxide, and methanol with potassium bicarbonate as the catalyst has been reported in this paper. As far as we know, it is the first time to use potassium bicarbonate only as the catalyst in the production process which is simple and cheap. Satisfactory conversion rate of propylene oxide and yield of the products could be achieved at the optimized conditions with quite a small amount of by-products. Our new method offers an attractive choice for the production of dimethyl carbonate in large-scale industry efficiently and environmental friendly.

  9. Nitrogen-doped carbon black as methanol tolerant electrocatalyst for oxygen reduction reaction in direct methanol fuel cells

    Nitrogen-doped metal free carbon catalysts were prepared via pyrolysis of polyaniline-coated carbon in different ratios with varying nitrogen content. The surface states and surface composition were investigated using XPS (X-ray photoelectron spectroscopy). XPS analysis confirms the presence of pyridinic and pyrollic nitrogen in the carbon network that is responsible for the oxygen reduction activity. The shift in onset potential of oxygen reduction on C:N (1:1) is ∼0.3 V more positive compared to Vulcan carbon, shows improved activity toward oxygen reduction reaction in acidic electrolyte. Hydrodynamic voltammetric studies confirm that the reduction of oxygen follows the 4e− pathway which leads to the formation of water.

  10. Direct synthesis of dimethyl carbonate and propylene glycol using potassium bicarbonate as catalyst in supercritical CO2

    Wen Yicun; Zhang Rui; Cang Yu; Zhang Jianchao; Liu Lixiao; Guo Xuhong; Fan Bin

    2015-01-01

    The improved one-pot synthesis of dimethyl carbonate and propylene glycol from propylene oxide, supercritical carbon dioxide, and methanol with potassium bicarbonate as the catalyst has been reported in this paper. As far as we know, it is the first time to use potassium bicarbonate only as the catalyst in the production process which is simple and cheap. Satisfactory conversion rate of propylene oxide and yield of the products could be achieved at the optimized conditions with quite a small ...

  11. Targeted Killing of Cancer Cells In vivo and In vitro with EGF-directed Carbon Nanotube-based Drug Delivery

    Bhirde, Ashwin A; Patel, Vyomesh; Gavard, Julie; Zhang, Guofeng; Sousa, Alioscka A.; Masedunskas, Andrius; Leapman, Richard D.; Weigert, Roberto; Gutkind, J. Silvio; Rusling, James F.

    2009-01-01

    Carbon nanotube-based drug delivery holds great promise for cancer therapy. Herein we report the first targeted, in vivo killing of cancer cells using a drug-single wall carbon nanotube (SWNT) bioconjugate, and demonstrate efficacy superior to non-targeted bioconjugates. First line anti-cancer agent cisplatin and epidermal growth factor (EGF) were attached to SWNTs to specifically target squamous cancer, and the non-targeted control was SWNT-cisplatin without EGF. Initialin vitro imaging stud...

  12. Corrigendum to "Sinusoidal potential cycling operation of a direct ethanol fuel cell to improving carbon dioxide yields" [J. Power Sources 268 (5 December 2014) 439-442

    Majidi, Pasha; Pickup, Peter G.

    2016-09-01

    The authors regret that Equation (5) is incorrect and has resulted in errors in Fig. 4 and the efficiencies stated on p. 442. The corrected equation, figure and text are presented below. In addition, the title should be 'Sinusoidal potential cycling operation of a direct ethanol fuel cell to improve carbon dioxide yields', and the reversible cell potential quoted on p. 441 should be 1.14 V. The authors would like to apologise for any inconvenience caused.

  13. Structure, mechanical, and frictional properties of hydrogenated fullerene-like amorphous carbon film prepared by direct current plasma enhanced chemical vapor deposition

    Wang, Yongfu; Gao, Kaixiong; Zhang, Junyan

    2016-07-01

    In this study, fullerene like carbon (FL-C) is introduced in hydrogenated amorphous carbon (a-C:H) film by employing a direct current plasma enhanced chemical vapor deposition. The film has a low friction and wear, such as 0.011 and 2.3 × 10-9mm3/N m in the N2, and 0.014 and 8.4 × 10-8mm3/N m in the humid air, and high hardness and elasticity (25.8 GPa and 83.1%), to make further engineering applications in practice. It has several nanometers ordered domains consisting of less frequently cross-linked graphitic sheet stacks. We provide new evidences for understanding the reported Raman fit model involving four vibrational frequencies from five, six, and seven C-atom rings of FL-C structures, and discuss the structure evolution before or after friction according to the change in the 1200 cm-1 Raman band intensity caused by five- and seven-carbon rings. Friction inevitably facilitates the transformation of carbon into FL-C nanostructures, namely, the ultra low friction comes from both such structures within the carbon film and the sliding induced at friction interface.

  14. Preparation and characterization of carbon molecular sieve (CMS) / SPEEK bilayer membranes and SPEEK / polyimide (PI) blend membranes for direct alcohols fuel cells / (DAFC) performance

    Maab, Husnul

    2009-01-01

    Summary This research work is based on the preparation of membranes from SPEEK with reduced fuel cross-over following two different approach: 1) the preparation of bilayer membranes from in-home sulfonated PEEK (Vitrex) and a thin layer of in-home prepared carbon molecular sieve (CMS) from polyimide (Matrimid 5218); 2) blending of SPEEK with polyimide polymers. In both ways, it was possible to decrease the fuel cross-over in both direct methanol fuel cell (DMFC) and direct ethanol fuel ce...

  15. Direct in situ measurement of Carbon Allocation to Mycorrhizal Fungi in a California Mixed-Conifer Forest

    Allen, M. F.

    2011-12-01

    Mycorrhizal fungi represent a large allocation of C to ecosystems, based on indirect measurements (tree girdling) and glasshouse extrapolations. However, we have no direct measures carbon (C) sink, in part because technologies for studying belowground dynamics on time scales at which roots and microbes grow and die have not existed. We initiated new sensor and observation platforms belowground to characterize and quantify belowground dynamics in a California mixed-conifer ecosystem. For the first time, we directly observed growth and mortality of mycorrhizal fungi in situ. We measured soil CO2, T and θ at 5-min intervals into the soil profile. Using our automated minirhizotron (AMR) for hyphal dynamics and the Bartz minirhizotron for longer-term and spatial variation in roots and rhizomorphs, we measured root, rhizomorph, hyphal growth, and belowground phenology up to 4x daily. These data are coupled with sensors measuring eddy flux of water and CO2, sapflow for water fluxes and C fixation activity, and photographs for leaf phenology. Because our data were collected at short intervals, we can describe integrative C exchange using the DayCent model for NPP and measured NPP of rhizomorphs, and fungal hyphae. Here, we focused on an arbuscular mycorrhiza dominated meadow and an ectomycorrhizal pine/oak forest at the James Reserve, in southern California. By daily measuring hyphal growth and mortality, we constructed life-span estimates of mycorrhizal hyphae, and from these, C allocation estimates. In the meadow, the NPP was 141g/m2/y, with a productivity of fine root+internal AM fungi of 76.5g C/m2/y, and an estimated 10% of which is AM fungal C allocation (7.7 g/m2/y). Extramatrical AM hyphal peak standing crop was 10g/m2, with a lifespan of 46 days (with active hyphae persisting for ~240 days per year days). Thus, the annual AM fungal allocation was 7.7g C/m2/y internal and 52g/m2/y external, for a net allocation of 84g C/m2/y, or 60% of the estimated NPP. In the

  16. Direct Radiative Effect and Heating Rate of black carbon aerosol: high time resolution measurements and source-identified forcing effects

    Ferrero, Luca; Mocnik, Grisa; Cogliati, Sergio; Comi, Alberto; Degni, Francesca; Di Mauro, Biagio; Colombo, Roberto; Bolzacchini, Ezio

    2016-04-01

    Black carbon (BC) absorbs sunlight in the atmosphere heating it. However, up to now, heating rate (HR) calculations from the divergence of the net radiative flux with altitude or from the modelling activity are too sparse. This work fills the aforementioned gap presenting a new methodology based on a full set of physical equations to experimentally determine both the radiative power density absorbed into a ground-based atmospheric layer (ADRE), and the consequent HR induced by the absorptive component of aerosol. In urban context, it is essentially related to the BC. The methodology is also applicable to natural components (i.e. dust) and is obtained solving the first derivative of the main radiative transfer equations. The ADRE and the consequent HR can be determined coupling spectral aerosol absorption measurements with the spectrally resolved measurements of the direct, diffuse downward radiation and the surface reflected radiance components. Moreover, the spectral absorption of BC aerosol allows its source apportionment (traffic and biomass burning (BB)) allowing the same apportionment on HR. This work reports one year of high-time resolution measurements (5 min) of sunlight absorption and HR induced by BC aerosol over Milan. A unique sampling site was set up from March 2015 with: 1) Aethalometer (AE-31, Magee Scientific, 7-λ), 2) the Multiplexer-Radiometer-Irradiometer which detects downward and reflected radiance (350-1000 nm in 3648 spectral bands) coupled with a rotating shadow-band to measure spectrally-resolved global and diffuse radiation (thus direct), 3) a meteorological station (LSI-Lastem) equipped with 3 pyranometers (global, diffuse and refrected radiation; 300-3000 nm), a thermohygrometer, a barometer, an anemometer, 4) condensation and optical particle counters (TSI 3775 and Grimm 1.107), 5) low volume sampler (FAI Hydra dual sampler, PM2.5 and PM10) for sample collection and chemistry determination. Results concerning the radiative power

  17. The Bi-Directional Prediction of Carbon Fiber Production Using a Combination of Improved Particle Swarm Optimization and Support Vector Machine

    Chuncai Xiao

    2014-12-01

    Full Text Available This paper creates a bi-directional prediction model to predict the performance of carbon fiber and the productive parameters based on a support vector machine (SVM and improved particle swarm optimization (IPSO algorithm (SVM-IPSO. In the SVM, it is crucial to select the parameters that have an important impact on the performance of prediction. The IPSO is proposed to optimize them, and then the SVM-IPSO model is applied to the bi-directional prediction of carbon fiber production. The predictive accuracy of SVM is mainly dependent on its parameters, and IPSO is thus exploited to seek the optimal parameters for SVM in order to improve its prediction capability. Inspired by a cell communication mechanism, we propose IPSO by incorporating information of the global best solution into the search strategy to improve exploitation, and we employ IPSO to establish the bi-directional prediction model: in the direction of the forward prediction, we consider productive parameters as input and property indexes as output; in the direction of the backward prediction, we consider property indexes as input and productive parameters as output, and in this case, the model becomes a scheme design for novel style carbon fibers. The results from a set of the experimental data show that the proposed model can outperform the radial basis function neural network (RNN, the basic particle swarm optimization (PSO method and the hybrid approach of genetic algorithm and improved particle swarm optimization (GA-IPSO method in most of the experiments. In other words, simulation results demonstrate the effectiveness and advantages of the SVM-IPSO model in dealing with the problem of forecasting.

  18. Large-scale and patternable graphene: direct transformation of amorphous carbon film into graphene/graphite on insulators via Cu mediation engineering and its application to all-carbon based devices

    Chen, Yu-Ze; Medina, Henry; Lin, Hung-Chiao; Tsai, Hung-Wei; Su, Teng-Yu; Chueh, Yu-Lun

    2015-01-01

    Chemical vapour deposition of graphene was the preferred way to synthesize graphene for multiple applications. However, several problems related to transfer processes, such as wrinkles, cleanness and scratches, have limited its application at the industrial scale. Intense research was triggered into developing alternative synthesis methods to directly deposit graphene on insulators at low cost with high uniformity and large area. In this work, we demonstrate a new concept to directly achieve growth of graphene on non-metal substrates. By exposing an amorphous carbon (a-C) film in Cu gaseous molecules after annealing at 850 °C, the carbon (a-C) film surprisingly undergoes a noticeable transformation to crystalline graphene. Furthermore, the thickness of graphene could be controlled, depending on the thickness of the pre-deposited a-C film. The transformation mechanism was investigated and explained in detail. This approach enables development of a one-step process to fabricate electrical devices made of all carbon material, highlighting the uniqueness of the novel approach for developing graphene electronic devices. Interestingly, the carbon electrodes made directly on the graphene layer by our approach offer a good ohmic contact compared with the Schottky barriers usually observed on graphene devices using metals as electrodes.Chemical vapour deposition of graphene was the preferred way to synthesize graphene for multiple applications. However, several problems related to transfer processes, such as wrinkles, cleanness and scratches, have limited its application at the industrial scale. Intense research was triggered into developing alternative synthesis methods to directly deposit graphene on insulators at low cost with high uniformity and large area. In this work, we demonstrate a new concept to directly achieve growth of graphene on non-metal substrates. By exposing an amorphous carbon (a-C) film in Cu gaseous molecules after annealing at 850 °C, the carbon (a

  19. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition–atomic absorption spectrophotometry

    Graphical abstract: Comparison of LOI data obtained by a conventional method and by the DMA. The dark line represents a 1:1 ratio. - Highlights: • A direct mercury analyzer was used to estimate total organic carbon. • Mercury and organic carbon were measured in oxbow lake sediment cores. • Temporal and spatial deposition of Hg in the Mississippi Delta were evaluated. - Abstract: The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p < 0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm−2 yr−1 for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s

  20. Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition–atomic absorption spectrophotometry

    Chen, Jingjing [College of Chemical Engineering, Zhejiang University of Technology, No. 18 Chaowang Road, Hangzhou, Zhejiang 310032 (China); Chakravarty, Pragya [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States); Davidson, Gregg R. [Department of Geology and Geological Engineering, University of Mississippi, University, MS 38677 (United States); Wren, Daniel G.; Locke, Martin A. [National Sedimentation Laboratory, United States Department of Agriculture, Agricultural Research Service, Oxford, MS 38655 (United States); Zhou, Ying, E-mail: yingzhou@zjut.edu.cn [College of Chemical Engineering, Zhejiang University of Technology, No. 18 Chaowang Road, Hangzhou, Zhejiang 310032 (China); Brown, Garry [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States); Cizdziel, James V., E-mail: cizdziel@olemiss.edu [Department of Chemistry and Biochemistry, University of Mississippi, University, MS 38677 (United States)

    2015-04-29

    Graphical abstract: Comparison of LOI data obtained by a conventional method and by the DMA. The dark line represents a 1:1 ratio. - Highlights: • A direct mercury analyzer was used to estimate total organic carbon. • Mercury and organic carbon were measured in oxbow lake sediment cores. • Temporal and spatial deposition of Hg in the Mississippi Delta were evaluated. - Abstract: The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p < 0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm{sup −2} yr{sup −1} for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s.

  1. Chemically Synthesised Pt Particles on Surface Oxidized Carbon Nanotubes as an Effective Catalyst for Direct Methanol Fuel Cell

    Mohammad; yari; Sajjad; Sadaghat; Sharehjini

    2007-01-01

    1 Results The synthesis, physical characterization and electrochemical analysis of Pt particles prepared using the surface oxidized carbon nanotubes prepared by chemically anchoring Pt onto the surface of the CNTs with 2.0 mol/L HNO3 by refluxing for 10 h to introduce surface functional groups.The particles of Pt are synthesized by reduction with sodium borohydride of H2PtCl6. The electro-oxidation of liquid methanol of this catalyst as a thin layer on glassy carbon electrode is investigated at room te...

  2. High-Temperature Co-electrolysis of Steam and Carbon Dioxide for Direct Production of Syngas; Equilibrium Model and Single-Cell Tests

    O' Brien, J. E.; Stoots, C. M.; Herring, J. S.; Hartvigsen, J. J.

    2007-07-01

    An experimental study has been completed to assess the performance of single solid-oxide electrolysis cells operating over a temperature range of 800 to 850ºC in the coelectrolysis mode, simultaneously electrolyzing steam and carbon dioxide for the direct production of syngas. The experiments were performed over a range of inlet flow rates of steam, carbon dioxide, hydrogen and nitrogen and over a range of current densities (-0.1 to 0.25 A/cm2) using single electrolyte-supported button electrolysis cells. Steam and carbon dioxide consumption rates associated with electrolysis were measured directly using inlet and outlet dewpoint instrumentation and a gas chromatograph, respectively. Cell operating potentials and cell current were varied using a programmable power supply. Measured values of open-cell potential and outlet gas composition are compared to predictions obtained from a chemical equilibrium coelectrolysis model. Model predictions of outlet gas composition based on an effective equilibrium temperature are shown to agree well with measurements. Cell area-specific resistance values were similar for steam electrolysis and coelectrolysis.

  3. Status quo and direction of developing low-carbon agriculture%低碳农业发展现状与发展趋势

    曹黎明; 潘晓华; 李茂柏

    2012-01-01

    为减少农业生产活动中的碳排放量,从发展精准农业、提高肥料使用效率、科学使用农药、节水灌溉、病虫害生态防治和农机农艺节能减排等方面探讨了低碳农业的发展趋势.%In order to reduce carbon emission in agricultural production,the direction of developing low-carbon agriculture is discussed in terms of developing precision agriculture, improving fertilizer-use efficiency,scientific use of pesticides,water-saving irrigation,ecological control of pests,and energy conservation and emission reduction in agricultural machinery and other agricultural practices.

  4. Effect of Nb, V and Ti additions on the yield strength of hot direct rolled thin slab cast low carbon steel

    Ingots of low carbon steels with additions of Nb, V and Ti were made in a manner that simulated thin slab casting, and were hot direct rolled. Mn and Si contents were kept constant at 1.4 wt% and 0.25 wt% respectively. Carbon contents were varied from 0.04-0.88 wt%, vanadium from 0.02-0.09 wt% and titanium from 0.007-0.025. The niobium content was kept constant i.e. 0.042 for all the ingots. A yield strength of 385 Mpa and a tensile strength of 470 MPa was achieved in the steel microalloyed only with Nb. It was shown that addition of vanadium alone and vanadium and titanium together to steel containing 0.042 wt% Nb did not increase yield or tensile strength further. (author)

  5. Polylactic acid-nanocrystalline carbonated hydroxyapatite (PLA-cHAP) composite: preparation and surface topographical structuring with direct laser writing (DLW)

    Garskaite, Edita; Drienovsky, Marian; Krajcovic, Jozef; Cicka, Roman; Palcut, Marian; Jonusauskas, Linas; Malinauskas, Mangirdas; Stankeviciute, Zivile; Kareiva, Aivaras

    2016-01-01

    The fabrication of polylactic acid (PLA)-carbonated hydroxyapatite (cHAP) composite material from synthesised phase pure nano-cHAP and melted PLA by mechanical mixing at 220-235{\\deg}C has been developed in this study. Topographical structuring of PLA-cHAP composite surfaces was performed by direct laser writing (DLW). Microstructured surfaces and the apatite distribution within the composite and formed grooves were evaluated by optical and scanning electron microscopies. The influence of the dopant concentration as well as the laser power and translation velocity on the composite surface morphology is discussed. The synthesis of carbonated hydroxyapatite (cHAP) nanocrystalline powders via wet chemistry approach from calcium acetate and diammonium hydrogen phosphate precursors together with crosslinking and complexing agents of polyethylene glycol, poly(vinyl alcohol) and triethanolamine is also reported. Thermal decomposition of the gels and formation of nanocrystalline cHAP were evaluated by thermal analysi...

  6. Direct synthesis of mesostructured carbon nanofibers decorated with silver-nanoparticles as a multifunctional membrane for water treatment

    Aboueloyoun Taha, Ahmed

    2015-12-01

    One-dimensional (1D) porous carbon nanofibers (CNFs) decorated by silver (Ag) nanoparticles (NPs) were prepared using a one-pot/self-template synthesis strategy by combining electrospinning and carbonization methods. The characterization results revealed that AgNPs were homogenously distributed along the CNFs and possessed a relatively uniform nano-size of about 12 nm. The novel membrane distinctively displayed enhanced photocatalytic activity under visible-light irradiation. The membrane exhibited excellent dye degradation and bacteria disinfection in batch experiments. The high photocatalytic activity can be attributed to the highly accessible surface areas, good light absorption capability, and high separation efficiency of photogenerated electron-hole pairs. The as-prepared membranes can be easily recycled because of their 1D property.

  7. Fabrication of multiwalled carbon nanotube-surfactant modified sensor for the direct determination of toxic drug 4-aminoantipyrine☆

    Jayant I. Gowda; Arunkumar T. Buddanavar; Sharanappa T. Nandibewoor

    2015-01-01

    A multi-walled carbon nanotube (MWCNT)-cetyltrimethylammonium bromide (CTAB) surfactant composite modified glassy carbon electrode (GCE) was developed as a novel system for the determination of 4-aminoantipyrine(AAP). The oxidation process was irreversible over the pH range studied and exhibited a diffusion controlled behavior. All experimental parameters were optimized. The combination of MWCNT-CTAB endows the biosensor with large surface area, good biological compatibility, electricity and stability, high selectivity and sensitivity. MWCNT-CTAB /GCE electrode gave a linear response for AAP from 5.0 × 10-9 to 4.0 × 10-8 M with a detection limit of 1.63 × 10-10 M. The modified electrode showed good selectivity against interfering species and also exhibited good reproducibility. The present electrochemical sensor based on the MWCNT-CTAB/GCE electrode was applied to the determination of AAP in real samples.

  8. Nucleophile-directed selectivity towards linear carbonates in the niobium pentaethoxide-catalysed cycloaddition of CO2 and propylene oxide

    Dutta, Barnali

    2014-01-01

    Homoleptic Nb-complexes combined with selected organic nucleophiles generate very active catalytic systems for the cycloaddition of propylene oxide and CO2 under ambient conditions. An unprecedented reaction pathway towards an acyclic organic carbonate is observed when extending the study to [Nb(OEt)5] in combination with 4-dimethylamino-pyridine (DMAP) or tetra-n-butylammonium bromide (TBAB). Mechanistic insights of the reaction are provided based on experimental and spectroscopic evidences. This journal is © the Partner Organisations 2014.

  9. Carbon Nanotube Emissions from Arc Discharge Production: Classification of Particle Types with Electron Microscopy and Comparison with Direct Reading Techniques

    Ludvigsson, Linus; Isaxon, Christina; Nilsson, Patrik; Tinnerberg, Håkan; Messing, Maria; Rissler, Jenny; Skaug, Vidar; Gudmundsson, Anders; Bohgard, Mats; Hedmer, Maria; Pagels, Joakim

    2016-01-01

    Introduction: An increased production and use of carbon nanotubes (CNTs) is occurring worldwide. In parallel, a growing concern is emerging on the adverse effects the unintentional inhalation of CNTs can have on humans. There is currently a debate regarding which exposure metrics and measurement strategies are the most relevant to investigate workplace exposures to CNTs. This study investigated workplace CNT emissions using a combination of time-integrated filter sampling for scanning electro...

  10. MECHANICAL AND THERMO–MECHANICAL PROPERTIES OF BI-DIRECTIONAL AND SHORT CARBON FIBER REINFORCED EPOXY COMPOSITES

    G. AGARWAL; Patnaik, A.; Sharma, R. K.

    2014-01-01

    This paper based on bidirectional and short carbon fiber reinforced epoxy composites reports the effect of fiber loading on physical, mechanical and thermo-mechanical properties respectively. The five different fiber loading, i.e., 10wt. %, 20wt. %, 30wt. %, 40wt. % and 50wt. % were taken for evaluating the above said properties. The physical and mechanical properties, i.e., hardness, tensile strength, flexural strength, inter-laminar shear strength and impact strength are determined to re...

  11. Understanding the mechanism of direct electrochemistry of mitochondria-modified electrodes from yeast, potato and bovine sources at carbon paper electrodes

    Although mitochondria have been used for bio-electrochemistry for over 5 years, little is known about their direct electrochemistry mechanism. This paper focuses on developing a better understanding of the electron transfer mechanism of mitochondria from three different organisms at carbon electrodes. Yeast, potato and bovine mitochondria have been successfully isolated and immobilized onto Toray paper electrodes via vapor deposited silica. Organelle-modified electrodes were first characterized using cyclic voltammetry. Similar electrochemical signals were obtained for all organisms. Direct electron transfer was observed when a metabolite of the Krebs cycle was present in the buffer solution. Control experiments based on the immobilization of two electron carriers contained in mitochondria, cytochrome c and a quinone (coenzyme Q10), tend to show the electron transfer mechanism to the carbon material comes from the quinone pool of the organelles. As quinones are known to be pH-dependent, we further investigated the response of the electrochemical signal of the three isolated mitochondria and the two electron carriers separately. The half wave potentials obtained from the organelles appeared to be pH-dependent and their variations are comparable to coenzyme Q10 rather than cytochrome c. Finally, extraction of both the cytochrome c and the quinone pool from intact mitochondria was performed to validate our hypothesis that direct electrochemistry of mitochondria happens via the quinone pool. Electrochemistry of immobilized quinone-depleted mitochondria validated the hypothesis that the mitochondria are communicating with the electrodes through the quinone pool

  12. The Role of Hydrate Films in the Effectiveness of Direct CO2 Injection as an Ocean Carbon Sequestration Strategy

    Goyet, C

    2004-05-06

    About one-third of the carbon dioxide (2 Pg C/yr of 6 Pg C/yr) we emit into the atmosphere is already being sequestered naturally by the ocean by the process of CO{sub 2} gas transfer across the air-sea interface. Over twenty years ago Brewer (1978) and Chen and Millero (1979) presented the first fundamental estimates of anthropogenic CO{sub 2} in the ocean based the hypothesis of CO{sub 2} penetration along isopycnal surfaces and observations of total inorganic carbon (TCO2) and total alkalinity (TA). At that time the anthropogenic CO{sub 2} signal was not as large as today and given the uncertainty of the approach, the uncertainties of the results were generally regarded as relatively large. However, since then, variations of this approach have been used to estimate anthropogenic CO{sub 2} in many areas of the world ocean. A recent modeling study using the DOCS model, confirms that penetration along isopycnal surfaces is the dominate mode of natural carbon sequestration by the ocean.

  13. Carbon nanospheres mediated delivery of nuclear matrix protein SMAR1 to direct experimental autoimmune encephalomyelitis in mice

    Chemmannur SV

    2016-05-01

    Full Text Available Sijo V Chemmannur,1,* Prasad Bhagat,2,* Bhalchandra Mirlekar,1 Kishore M Paknikar,2 Samit Chattopadhyay1,3 1Disease and Chromatin Biology Laboratory, National Center for Cell Science, Pune University Campus, Pune, Maharashtra, India; 2Center for Nanobioscience, Agharkar Research Institute, Pune, Maharashtra, India; 3Indian Institute of Chemical Biology, Kolkata, India *These authors have contributed equally to this work Abstract: Owing to the suppression of immune responses and associated side effects, steroid based treatments for inflammatory encephalitis disease can be detrimental. Here, we demonstrate a novel carbon nanosphere (CNP based treatment regime for encephalomyelitis in mice by exploiting the functional property of the nuclear matrix binding protein SMAR1. A truncated part of SMAR1 ie, the DNA binding domain was conjugated with hydrothermally synthesized CNPs. When administered intravenously, the conjugate suppressed experimental animal encephalomyelitis in T cell specific conditional SMAR1 knockout mice (SMAR-/-. Further, CNP-SMAR1 conjugate delayed the onset of the disease and reduced the demyelination significantly. There was a significant decrease in the production of IL-17 after re-stimulation with MOG. Altogether, our findings suggest a potential carbon nanomaterial based therapeutic intervention to combat Th17 mediated autoimmune diseases including experimental autoimmune encephalomyelitis. Keywords: carbon nanospheres, EAE, IL-17, SMAR1, Th17

  14. Direct comparison of ozonation and adsorption onto powdered activated carbon for micropollutant removal in advanced wastewater treatment.

    Altmann, Johannes; Ruhl, Aki Sebastian; Zietzschmann, Frederik; Jekel, Martin

    2014-05-15

    Organic micropollutants (OMPs) may occur ubiquitously in the aquatic environment. In order to protect the ecosystem and drinking water sources from potentially toxic effects, discharges of an increasing number of OMPs are being regulated. OMP removal from wastewater treatment plant (WWTP) effluents as a point source is a preferred option with removal by adsorption onto powdered activated carbon (PAC) and OMP transformation to presumably harmless compounds by ozonation as the most promising techniques. In this study, effluents of four WWTPs were treated with PAC and ozone in bench-scale experiments to compare the removal efficiencies of seven relevant OMPs. Concentrations of carbamazepine and diclofenac were reduced by more than 90% with 20 mg/L PAC or 5-7 mg/L ozone (0.5 mg O3 per mg dissolved organic carbon (DOC)). Comparing typical doses for practical applications ozonation proved to be more efficient for abatement of sulfamethoxazole, while removal of benzotriazole and iomeprol was comparatively more efficient with activated carbon. While well known for ozonation, DOC-normalized doses were also applied to PAC and correlated better to relative OMP removal than volume proportional PAC addition. Furthermore, OMP removal efficiencies corresponded well with the reduction of ultraviolet light absorption at 254 nm for both treatment options. PMID:24607314

  15. THE EFFECT OF IODOMETHANE ON THE DIRECT SYNTHESIS OF DIMETHYL CARBONATE%碘甲烷在碳酸二甲酯直接合成中的作用

    江琦; 李涛; 刘峰; 黄仲涛

    1999-01-01

    @@ Dimethyl carbonate (DMC) is an environmentally friendly compound and a substitutive intermediate for highly toxic phosgene or dimethyl sulfate in carbonylation and methylation reactions as well as a promising octane booster. The common methods for its preparation are the oxidative carbonylation of methanol catalyzed by a variety of transition metal ions and the transesterification of ethylene carbonate or propene carbonate with methanol[1]. The direct synthesis of DMC from carbon dioxide and methanol is a challenging route in which the most abundant carbon resources and a main greenhouse gas is used as feedstock. A new method for the direct synthesis of DMC catalyzed by the methoxide of main group metal has attracted more and more attention since it was reported[2~6] . However the lower conversion of the reaction has become the main obstacle for its application. In this letter, an efficient promoter for the direct synthesis of DMC is reported.

  16. Direct carbon-carbon bond formation via reductive soft enolization: a syn-selective Mannich addition of α-iodo thioesters.

    Truong, Ngoc; Sauer, Scott J; Seraphin-Hatcher, Cyndie; Coltart, Don M

    2016-08-16

    The β-amino carboxylic acid moiety is a key feature of numerous important biologically active compounds. We describe a syn-selective direct Mannich addition reaction that uses α-iodo thioesters and sulfonyl imines and produces β-amino thioesters. Enolate formation is achieved by reductive soft enolization. The products of the reaction provide straightforward access to biologically important β-lactams through a variety of known reactions. PMID:27492274

  17. Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics

    Amin, Nevine Kamal, E-mail: nkamalamin@yahoo.com [Chemical Engineering Department, Faculty of Engineering, Alexandria University, Alexandria (Egypt)

    2009-06-15

    The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (R{sup 2} > 0.99) and intra-particle diffusion as one of the rate determining steps. Langmuir, Freundlich, Temkin, Dubinin-RadushKevich (D-R) and Harkins-Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, various thermodynamic parameters, such as standard Gibbs free energy ({Delta}G{sup o}), standard enthalpy ({Delta}H{sup o}), standard entropy ({Delta}S{sup o}), and the activation energy (E{sub a}) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate.

  18. Removal of direct blue-106 dye from aqueous solution using new activated carbons developed from pomegranate peel: Adsorption equilibrium and kinetics

    The use of cheap, high efficiency and ecofriendly adsorbent has been studied as an alternative source of activated carbon for the removal of dyes from wastewater. This study investigates the use of activated carbons prepared from pomegranate peel for the removal of direct blue dye from aqueous solution. A series of experiments were conducted in a batch system to assess the effect of the system variables, i.e. initial pH, temperature, initial dye concentration adsorbent dosage and contact time. The results showed that the adsorption of direct blue dye was maximal at pH 2, as the amount of adsorbent increased, the percentage of dye removal increased accordingly but it decreased with the increase in initial dye concentration and solution temperature. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (R2 > 0.99) and intra-particle diffusion as one of the rate determining steps. Langmuir, Freundlich, Temkin, Dubinin-RadushKevich (D-R) and Harkins-Jura isotherms were used to analyze the equilibrium data at different temperatures. In addition, various thermodynamic parameters, such as standard Gibbs free energy (ΔGo), standard enthalpy (ΔHo), standard entropy (ΔSo), and the activation energy (Ea) have been calculated. The adsorption process of direct blue dye onto different activated carbons prepared from pomegranate peel was found to be spontaneous and exothermic process. The findings of this investigation suggest that the physical sorption plays a role in controlling the sorption rate.

  19. Brown carbon aerosols from burning of boreal peatlands: microphysical properties, emission factors, and implications for direct radiative forcing

    Chakrabarty, Rajan K.; Gyawali, Madhu; Yatavelli, Reddy L. N.; Pandey, Apoorva; Watts, Adam C.; Knue, Joseph; Chen, Lung-Wen A.; Pattison, Robert R.; Tsibart, Anna; Samburova, Vera; Moosmüller, Hans

    2016-03-01

    The surface air warming over the Arctic has been almost twice as much as the global average in recent decades. In this region, unprecedented amounts of smoldering peat fires have been identified as a major emission source of climate-warming agents. While much is known about greenhouse gas emissions from these fires, there is a knowledge gap on the nature of particulate emissions and their potential role in atmospheric warming. Here, we show that aerosols emitted from burning of Alaskan and Siberian peatlands are predominantly brown carbon (BrC) - a class of visible light-absorbing organic carbon (OC) - with a negligible amount of black carbon content. The mean fuel-based emission factors for OC aerosols ranged from 3.8 to 16.6 g kg-1. Their mass absorption efficiencies were in the range of 0.2-0.8 m2 g-1 at 405 nm (violet) and dropped sharply to 0.03-0.07 m2 g-1 at 532 nm (green), characterized by a mean Ångström exponent of ≈ 9. Electron microscopy images of the particles revealed their morphologies to be either single sphere or agglomerated "tar balls". The shortwave top-of-atmosphere aerosol radiative forcing per unit optical depth under clear-sky conditions was estimated as a function of surface albedo. Only over bright surfaces with albedo greater than 0.6, such as snow cover and low-level clouds, the emitted aerosols could result in a net warming (positive forcing) of the atmosphere.

  20. Directive Production of Pullulan by Altering Cheap Source of Carbons and Nitrogen at 5 L Bioreactor Level

    Sheoran, Sunil K.; Kashyap Kumar Dubey; Tiwari, D. P.; Singh, Bhanu P.

    2012-01-01

    In the present paper, attempts have been made to control the production of pullulan by supplementing commercial source of carbons and protein, timely. Pullulan production was regulated by supplying full fat soya flour and hydrolyzed soya extract, individually and in combination. Pullulan quantification was assayed for sensitivity to pullulanase. Aureobasidium pullulans was found to produce 125.7 gL−1 of pullulan. The rotation speed of shake flask, the pH of broth, and the supply of air were m...

  1. Influence Of Temperature On The Rate Of Copper Recovery From The Slag Of The Flash Direct-To-Blister Process By A Solid Carbon Reducer

    Madej P.

    2015-09-01

    Full Text Available The aim of the work was to investigate the influence of temperature on the rate of copper removal from the obtained slag from the flash direct-to-blister process by means of a carbon reducer. The slag used in this work was taken from the direct-to-blister Outokumpu flash furnace at the smelter in Głogów, and graphite penetrators were used as the slag reducers. The experiment was carried out at 1573 K, 1623 K and 1673 K. It was found that the rate of the de-coppering process of the “Głogów” slag increased with the increase of temperature.

  2. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  3. Surface modification of carbon fiber by direct growth of zinc oxide nanowalls using a radio-frequency magnetron sputtering technique

    Zinc oxide nanowalls have been grown uniformly on a carbon fiber substrate at room temperature using a radio-frequency magnetron sputtering technique. The synthesis process involved two steps; application of catalyst using a solution process and subsequent radio-frequency sputter deposition of zinc oxide. The nanowalls were examined by field emission scanning electron microscopy for their microstructure and morphology while their nanostructure was studied by high resolution transmission electron microscopy. Both the X-ray and the electron diffraction techniques were used for crystallographic analysis of the produced nanowalls. Selected area electron diffraction and high resolution lattice image showed highly crystalline structure of the nanowalls. Photoluminescence analysis was carried out for the determination of their optical characteristics which showed a strong ultra violet peak at 393 nm and violet peak centered at 401 nm. The latter is a characteristic peak of zinc oxide which demonstrates oxygen rich composition of nanowalls. - Highlights: • Low temperature growth method • Zinc oxide nanowall growth on carbon fiber • Microstructural analysis using high resolution electron microscopy • X-ray and electron diffraction analysis • Photoluminescence characteristics

  4. Direct evidence of chemically inhomogeneous, nanostructured, Si-O buried interfaces and their effect on the efficiency of carbon nanotube/Si photovoltaic heterojunctions

    Pintossi, Chiara

    2013-09-12

    An angle resolved X-ray photoemission study of carbon nanotube/silicon hybrid photovoltaic (PV) cells is reported, providing a direct probe of a chemically inhomogeneous, Si-O buried interface between the carbon nanotube (CNT) networked layer and the n-type Si substrate. By changing the photoelectron takeoff angle of the analyzer, a nondestructive in-depth profiling of a CNT/SiOx/SiO2/Si complex interface is achieved. Data are interpreted on the basis of an extensive modeling of the photoemission process from layered structures, which fully accounts for the depth distribution function of the photoemitted electrons. As X-ray photoemission spectroscopy provides direct access to the buried interface, the aging and the effects of chemical etching on the buried interface have been highlighted. This allowed us to show how the thickness and the composition of the buried interface can be related to the efficiency of the PV cell. The results clearly indicate that while SiO2 is related to an increase of the efficiency, acting as a buffer layer, SiOx is detrimental to cell performances, though it can be selectively removed by etching in HF vapors. © 2013 American Chemical Society.

  5. Carbon Nanotubes Supported Pt-Ru-Ni as Methanol Electro-Oxidation Catalyst for Direct Methanol Fuel Cells

    Fei Ye; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    Carbon nanotubes (CNTs) supported Pt-Ru and Pt-Ru-Ni catalysts were prepared by chemical reduction of metal precursors with sodium borohydride at room temperature. The crystallographic properties and composition of the catalysts were characterized by X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, and the catalytic activity and stability for methanol electro-oxidation were measured by electrochemical impedance spectroscopy (EIS), linear sweep voltammetries (LSV), and chronoamperometry (CA). The results show that the catalysts exhibit face-centered cubic (fcc) structure.The particle size of Pt-Ru-Ni/CNTs catalyst is about 4.8 nm. The catalytic activity and stability of the Pt-Ru-Ni/CNTs catalyst are higher than those of Pt-Ru/CNTs catalyst.

  6. Enhanced electromagnetic loss of polybenzoxazole copolymerized with etched multiwalled carbon nanotube via direct Friedel–Crafts acylation

    Etched multiwalled carbon nanotube (EMCNT) was prepared via an in situ reaction between Si and MCNT induced by the reaction between Na and I2. Subsequently, EMCNTs was subjected to a copolymerization reaction with 4,6-diaminoresorcinol salt (DAR·2HCl) and terephthalic acid (TA) in polyphosphoric acid (PPA) by Friedel–Crafts acylation reaction without any acid treatment or modification. The structure and morphology of the as-prepared poly(p-phenylene benzobisoxazole) (PBO)/EMCNT nanocomposites were characterized by x-ray diffraction (XRD), Raman spectra, and transmission electron microscopy (TEM). The scanning electronic microscope (SEM) images indicated that the EMCNTs can disperse in PBO matrix uniformly without agglomeration. And the electromagnetic properties of the obtained PBO/EMCNT nanocomposites characterized by vector network analyzer (VNA) showed that the introduced PBO/EMCNT composites exhibited a greater enhancement in dielectric loss and magnetic loss than PBO. (papers)

  7. Direct and indirect effects of ammonia, ammonium and nitrate on phosphatase activity and carbon fluxes from decomposing litter in peatland

    Here we investigate the response of soils and litter to 5 years of experimental additions of ammonium (NH4), nitrate (NO3), and ammonia (NH3) to an ombrotrophic peatland. We test the importance of direct (via soil) and indirect (via litter) effects on phosphatase activity and efflux of CO2. We also determined how species representing different functional types responded to the nitrogen treatments. Our results demonstrate that additions of NO3, NH4 and NH3 all stimulated phosphatase activity but the effects were dependent on species of litter and mechanism (direct or indirect). Deposition of NH3 had no effect on efflux of CO2 from Calluna vulgaris litter, despite it showing signs of stress in the field, whereas both NO3 and NH4 reduced CO2 fluxes. Our results show that the collective impacts on peatlands of the three principal forms of nitrogen in atmospheric deposition are a result of differential effects and mechanisms on individual components. - We found that nitrogen deposition affects microbial activity associated with litter through both indirect and direct mechanisms, but these effects were dependent on the chemical form of inorganic nitrogen compounds.

  8. Direct analysis of δ13C and concentration of dissolved organic carbon (DOC) in environmental samples by TOC-IRMS

    Kirkels, Frédérique; Cerli, Chiara; Federherr, Eugen; Kalbitz, Karsten

    2014-05-01

    Dissolved organic carbon (DOC) plays an important role in carbon cycling in terrestrial and aquatic systems. Stable isotope analysis (delta 13C) of DOC could provide valuable insights in its origin, fluxes and environmental fate. Precise and routine analysis of delta 13C and DOC concentration are therefore highly desirable. A promising, new system has been developed for this purpose, linking a high-temperature combustion TOC analyzer trough an interface with a continuous flow isotope ratio mass spectrometer (Elementar group, Hanau, Germany). This TOC-IRMS system enables simultaneous stable isotope (bulk delta 13C) and concentration analysis of DOC, with high oxidation efficiency by high-temperature combustion for complex mixtures as natural DOC. To give delta 13C analysis by TOC-IRMS the necessary impulse for broad-scale application, we present a detailed evaluation of its analytical performance for realistic and challenging conditions inclusive low DOC concentrations and environmental samples. High precision (standard deviation, SD predominantly < 0.15 permil) and accuracy (R2 = 0.9997, i.e. comparison TOC-IRMS and conventional EA-IRMS) were achieved by TOC-IRMS for a broad diversity of DOC solutions. This precision is comparable or even slightly better than that typically reported for EA-IRMS systems, and improves previous techniques for δ13C analysis of DOC. Simultaneously, very good precision was obtained for DOC concentration measurements. Assessment of natural abundance and slightly 13C enriched DOC, a wide range of concentrations (0.2-150 mgC/L) and injection volumes (0.05-3 ml), demonstrated good analytical performance with negligible memory effects, no concentration/volume effects and a wide linearity. Low DOC concentrations (< 2 mgC/L), were correctly analyzed without any pre-concentration. Moreover, TOC-IRMS was successfully applied to analyze DOC from diverse terrestrial, freshwater and marine environments (SD < 0.23 permil). In summary, the TOC

  9. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes

    Graphical abstract: -- Highlights: •A graphene and multi-walled carbon nanotubes nanocomposite was prepared. •Hemoglobin and nanocomposite modified carbon ionic liquid electrode was fabricated. •Direct electrochemistry of hemoglobin was realized on the modified electrode. •Bioelectrocatalysis towards the reduction of different substrates was enhanced. -- Abstract: A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (ks) as 0.97 s−1. The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L−1 with a detection limit of 0.0153 mmol L−1 (3σ), H2O2 in the concentration range from 0.1 to 516.0 mmol L−1 with a detection limit of 34.9 nmol/L (3σ) and NaNO2 in the concentration range from 0.5 to 650.0 mmol L−1 with a detection limit of 0.282 μmol L−1 (3σ). So the proposed electrode had the

  10. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 China (China); College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Cao, Lili; Deng, Ying; Gong, Shixing [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Shi, Fan; Li, Gaonan; Sun, Zhenfan [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 China (China)

    2013-06-05

    Graphical abstract: -- Highlights: •A graphene and multi-walled carbon nanotubes nanocomposite was prepared. •Hemoglobin and nanocomposite modified carbon ionic liquid electrode was fabricated. •Direct electrochemistry of hemoglobin was realized on the modified electrode. •Bioelectrocatalysis towards the reduction of different substrates was enhanced. -- Abstract: A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (k{sub s}) as 0.97 s{sup −1}. The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L{sup −1} with a detection limit of 0.0153 mmol L{sup −1} (3σ), H{sub 2}O{sub 2} in the concentration range from 0.1 to 516.0 mmol L{sup −1} with a detection limit of 34.9 nmol/L (3σ) and NaNO{sub 2} in the concentration range from 0.5 to 650.0 mmol L{sup −1} with a detection limit of 0

  11. Direct formation of anatase TiO2 nanoparticles on carbon nanotubes by atomic layer deposition and their photocatalytic properties.

    Huang, Sheng-Hsin; Liao, Shih-Yun; Wang, Chih-Chieh; Kei, Chi-Chung; Gan, Jon-Yiew; Perng, Tsong-Pyng

    2016-10-01

    TiO2 with different morphology was deposited on acid-treated multi-walled carbon nanotubes (CNTs) by atomic layer deposition at 100 °C-300 °C to form a TiO2@CNT structure. The TiO2 fabricated at 100 °C was an amorphous film, but became crystalline anatase nanoparticles when fabricated at 200 °C and 300 °C. The saturation growth rates of TiO2 nanoparticles at 300 °C were about 1.5 and 0.4 Å/cycle for substrate-enhanced growth and linear growth processes, respectively. It was found that the rate constants for methylene blue degradation by the TiO2@CNT structure formed at 300 °C were more suitable to fit with second-order reaction. The size of 9 nm exhibited the best degradation efficiency, because of the high specific area and appropriate diffusion length for the electrons and holes. PMID:27576914

  12. Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production

    Rau, Greg H.; Carroll, Susan A.; Bourcier, William L.; Singleton, Michael J.; Smith, Megan M.; Aines, Roger D.

    2013-01-01

    We experimentally demonstrate the direct coupling of silicate mineral dissolution with saline water electrolysis and H2 production to effect significant air CO2 absorption, chemical conversion, and storage in solution. In particular, we observed as much as a 105-fold increase in OH− concentration (pH increase of up to 5.3 units) relative to experimental controls following the electrolysis of 0.25 M Na2SO4 solutions when the anode was encased in powdered silicate mineral, either wollastonite o...

  13. Investigation of the environmental Kuznets curve for carbon emissions in Malaysia: Do foreign direct investment and trade matter?

    Environmental degradation has become a central issue of discussion among the economists and environmentalists. In view of Malaysia's position as one of the main contributors to CO2 emissions in Asia and its status as a fast growing economy, it is vital, therefore, to conduct a study to identify the relationship between economic growth and CO2 emissions for Malaysia. This study attempts to examine empirically the environmental Kuznets curve hypothesis for Malaysia in the presence of foreign direct investment and trade openness both in the short- and long-run for the period 1970 to 2008.The bounds testing approach and Granger causality methodology are applied to test the interrelationships of the variables. The results of our study indicate that the inverted-U shaped relationship does exist between economic growth and CO2 emission in both the short- and long-run for Malaysia after controlling for two additional explanatory variables, namely FDI and trade. Importantly, the results of the study also provide some crucial policy recommendations to the policy makers. - Highlights: • Examining environmental Kuznets curve hypothesis by incorporating FDI and trade. • FDI promotes higher economic growth and leads to higher environmental degradation. • Both FDI and trade directly influence CO2 emission and economic growth. • Attraction of technology-oriented FDI is crucial for the quality of environment

  14. Direct carbonization of cobalt-doped NH2-MIL-53(Fe) for electrocatalysis of oxygen evolution reaction

    Han, Yujie; Zhai, Junfeng; Zhang, Lingling; Dong, Shaojun

    2015-12-01

    In this work, we synthesized high-performance electrocatalysts for oxygen evolution reaction (OER) by one-step carbonization of cobalt(Co)-doped NH2-MIL-53(Fe) with different molar ratios between Fe and Co. The results showed that the as-prepared composite with a molar ratio between Fe and Co = 1 : 3 and the calcination temperature of 550 °C displayed the best OER activity, denoted as MOF(Fe1-Co3)550N. The MOF(Fe1-Co3)550N possesses a microporous structure with a high Brunauer-Emmett-Teller (BET) surface area of 235.37 m2.g-1. It shows excellent OER catalytic behavior in 0.1 M KOH solution. The overpotential at 10 mA cm-2 is 0.39 V and the Tafel slope is 72.9 mV dec-1, which is comparable to that of the as-synthesized RuO2. The satisfactory results are attributed to the presence of pyridine N, Co3O4, the enlarged surface area and the micropore structures after calcination.In this work, we synthesized high-performance electrocatalysts for oxygen evolution reaction (OER) by one-step carbonization of cobalt(Co)-doped NH2-MIL-53(Fe) with different molar ratios between Fe and Co. The results showed that the as-prepared composite with a molar ratio between Fe and Co = 1 : 3 and the calcination temperature of 550 °C displayed the best OER activity, denoted as MOF(Fe1-Co3)550N. The MOF(Fe1-Co3)550N possesses a microporous structure with a high Brunauer-Emmett-Teller (BET) surface area of 235.37 m2.g-1. It shows excellent OER catalytic behavior in 0.1 M KOH solution. The overpotential at 10 mA cm-2 is 0.39 V and the Tafel slope is 72.9 mV dec-1, which is comparable to that of the as-synthesized RuO2. The satisfactory results are attributed to the presence of pyridine N, Co3O4, the enlarged surface area and the micropore structures after calcination. Electronic supplementary information (ESI) available: Additional information about the TEM images of different catalysts, XRD comparison of NH2-MIL-53(Fe) and other cobalt doped NH2-MIL-53(Fe), BET measurements of MOF(Fe1-Co3

  15. Impacts of EU carbon emission trade directive on energy-intensive industries. Indicative micro-economic analyses

    The cost impacts from the European emission trading system (ETS) on energy-intensive manufacturing industries have been investigated. The effects consist of direct costs associated to the CO2 reduction requirements stated in the EU Directive, and of indirect costs of comparable magnitude that originate from a higher electricity price triggered by the ETS in the power sector. The total cost impacts remain below 2% of the production value for most industries within the ETS in the Kyoto period. In the post-Kyoto phase assuming a 30% CO2 reduction, the total cost impact may raise up to 8% of production value in the heaviest industry sectors. In steel and cement industries the cost impacts are 3-4 fold compared to the least affected pulp and paper and oil refining. Electricity-intensive industries outside the ETS will also be affected, for example in aluminum and chlorine production the indirect cost impacts from ETS could come up to 10% of production value already in the Kyoto period. As industry sectors are affected differently by the ETS some correcting mechanisms may be worthwhile to consider in securing the operation of the most electricity-intensive sectors, e.g. balancing taxation schemes that may include as income source a levy on the wind-fall profits of the power sector due to ETS. A future improvement in ETS for industries within the scheme could be scaling of the emission reduction requirement so that the relative total emission reduction costs are at about the same level. (author)

  16. Photothermal response of CVD synthesized carbon (nanospheres/aqueous nanofluids for potential application in direct solar absorption collectors: a preliminary investigation

    Poinern GE

    2012-07-01

    Full Text Available Gérrard Eddy Jai Poinern,1 Sridevi Brundavanam,1 Monaliben Shah,1 Iafeta Laava,2 Derek Fawcett11Murdoch Applied Nanotechnology Research Group, 2Department of Physics, Energy Studies and Nanotechnology, Murdoch University, Perth, AustraliaAbstract: Direct-absorption solar collectors have the potential to offer an unlimited source of renewable energy with minimal environmental impact. Unfortunately, their performance is limited by the absorption efficiency of the working fluid. Nanoparticles of functionalized carbon nanospheres (CNS have the potential to improve the photothermal properties of the working fluid. CNS are produced by the pyrolysis of acetylene gas in a tube-based electric furnace/chemical vapor deposition apparatus. The reaction takes place at 1000°C in the presence of nitrogen gas without the use of a catalyst. The synthesized CNS were examined and characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and ultraviolet-visible analysis. The CNS powders with a mean particle size of 210 nm were then functionalized using tetraethylammonium hydroxide ([C2H5]4 N[OH] and used to produce a series of aqueous nanofluids with varying mass content. The photothermal response of both the nanofluids and films composed of CNS were investigated under 1000 W/m2 solar irradiation.Keywords: solar absorption, carbon nanospheres, nanofluids, photothermal

  17. Synthesis of nickel oxides nanoparticles on glassy carbon as an electron transfer facilitator for horseradish peroxidase: Direct electron transfer and H2O2 determination

    In this study, horseradish peroxidase/nickel oxides nanoparticles/glassy carbon (HRP/NiO NPs/GC) electrode was prepared by first applying nickel oxides nanoparticles on glassy carbon surface and then horseradish peroxidase immobilized on the NiO NPs. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used as a diagnostic tools to identify the synthesized NiO NPs. Immobilized HRP showed an electrochemical redox behavior pertained to HRP(Fe(III)-Fe(II)) by direct electron transfer between protein and nanoparticles with a formal potential (E0') of - 55.5 mV (vs. Ag/AgCl and 141.5 mV vs. NHE) in 50 mM phosphate buffer solution (PBS). The anodic charge transfer coefficient (α) and heterogeneous electron transfer rate constant (ks) were 0.42 and 0.75 s-1, respectively. Biocatalytic activity of HRP/NiO NPs/GC electrode for reduction of hydrogen peroxide and application to hydrogen peroxide determination was exemplified.

  18. Carbon incorporated FeN/C electrocatalyst for oxygen reduction enhancement in direct methanol fuel cells: X-ray absorption approach to local structures

    Highlights: → Nonprecious iron nitride catalysts demonstrate an excellent anti-methanol crossover performance; it could be benefic for the applications in direct methanol fuel cells (DMFCs). → H2O2 is poorly yielded in the electrochemical test. It could be helpful for a proton exchange membrane, since H2O2 would etch the membrane. → Tafel plot and rotating ring disk electrode (RRDE) both give that electron transfer numbers are close to 4 in oxygen reduction reaction (ORR), indicating the major product as H2O. → Fe-C contributes to the FeCN/C catalyst by using EXAFS analysis. FeCN nanoparticles would disperse on C supports and may give ORR activity. - Abstract: The C-containing iron nitride electrocatalyst is fabricated by chelating N-containing species and Fe2+ with a carbon support under heat treatment in an NH3 atmosphere, which induces the oxygen reduction reaction activity. This is the first demonstration of forming FexC species on iron nitride materials. The correlation between the electrochemical properties and structures are aided to elucidate their features under investigation by using X-ray absorption spectroscopy. A rotating ring disk electrode test is conducted in sulfuric acid solution and the results reveal the low H2O2 yield and approximately 4e- transfer process of the carbon-containing FeN/C electrocatalyst.

  19. Direct Synthesis of Dimethyl Carbonate from CO2 and CH3OH Using 0.4 nm Molecular Sieve Supported Cu-Ni Bimetal Catalyst

    陈惠玲; 王栓紧; 肖敏; 韩冬梅; 卢一新; 孟跃中

    2012-01-01

    The 0.4 nm molecular sieve supported Cu-Ni bimetal catalysts for direct synthesis of dimethyl carbonate (DMC) from CO 2 and CH 3 OH were prepared and investigated. The synthesized catalysts were fully characterized by BET, XRD (X-ray diffraction), TPR (temperature programmed reduction), IR (infra-red adsorption), NH 3-TPD (temperature programmed desorption) and CO 2-TPD (temperature programmed desorption) techniques. The results showed that the surface area of catalysts decreased with increasing metal content, and the metals as well as Cu-Ni alloy co-existed on the reduced catalyst surface. There existed interaction between metal and carrier, and moreover, metal particles affected obviously the acidity and basicity of carrier. The large amount of basic sites facilitated the activation of methanol to methoxyl species and their subsequent reaction with activated carbon dioxide. The catalysts were evaluated in a continuous tubular fixed-bed micro-gaseous reactor and the catalyst with bimetal loading of 20% (by mass) had best catalytic activities. Under the conditions of 393 K, 1.1 MPa, 5 h and gas space velocity of 510 h 1 , the selectivity and yield of DMC were higher than 86.0 % and 5.0 %, respectively.

  20. A CNT (carbon nanotube) paper as cathode gas diffusion electrode for water management of passive μ-DMFC (micro-direct methanol fuel cell) with highly concentrated methanol

    A novel MEA (membrane electrode assembly) structure of passive μ-DMFC (micro-direct methanol fuel cell) controls water management and decreases methanol crossover. The CNT (carbon nanotube) paper replacing CP (carbon paper) as GDL (gas diffusion paper) enhances water back diffusion which passively prevents flooding in the cathode and promotes low methanol crossover. Moreover, the unique structure of CNT paper can also enhance efficiency of oxygen mass transport and catalyst utilization. The passive μ-DMFC with CNT-MEA exhibits significantly higher performance than passive μ-DMFC with CP-MEA and can operate in high methanol concentration, showing the peak power density of 23.2 mW cm−2. The energy efficiency and fuel utilization efficiency are obviously improved from 11.54% to 22.7% and 36.61%–49.34%, respectively, and the water transport coefficient is 0.47 which is lower than previously reported passive μ-DMFC with CP. - Highlights: • This novel GDL (gas diffusion layer) solves water management and methanol crossover. • This GDL creates a hydraulic pressure in the cathode increasing water back diffusion. • This GDL improves the electrical conductivity and activity of catalyst

  1. Hydrogen-free diamond-like carbon films prepared by microwave electron cyclotron resonance plasma-enhanced direct current magnetron sputtering

    Hydrogen-free diamond-like carbon (DLC) films were prepared by means of microwave electron cyclotron resonance plasma enhanced direct current magnetron sputtering. To study the influence of enhanced plasma on film fabrication and properties, the structures as well as mechanical and electrical properties of these films were studied as a function of applied microwave power. Results showed that higher microwave power could induce higher plasma density and electron temperature. The hardness increased from 3.5 GPa to 13 GPa with a variation of microwave power from 0 W to 1000 W. The resistivity showed a drastic increase from 4.5 x 104 Ωcm at 0 W to 1.3 x 1010 Ωcm at 1000 W. The variation of the intensity ratio I(D)/I(G) and the position of the G-peak of the DLC films with respect to changes in microwave power were also investigated by Raman spectroscopy.

  2. Novel Biological Conversion of Hydrogen and Carbon Dioxide Directly into Biodiesel: Cooperative Research and Development Final Report, CRADA Number: CRD-10-408

    Maness, P. C.

    2014-06-01

    OPX Biotechnologies, Inc. (OPX), the National Renewable Energy Laboratory (NREL), and Johnson Matthey will develop and optimize a novel, engineered microorganism that directly produces biodiesel from renewable hydrogen (H2) and carbon dioxide (CO2). The proposed process will fix CO2 utilizing H2 to generate an infrastructure-compatible, energy-dense fuel at costs of less than $2.50 per gallon, with water being produced as the primary byproduct. NREL will perform metabolic engineering on the bacterium Cupriavidus necator (formerly Ralstonia eutropha) and a techno-economic analysis to guide future scale-up work. H2 and CO2 uptakes rates will be genetically increased, production of free fatty acids will be enhanced and their degradation pathway blocked in order to meet the ultimate program goals.

  3. Direct synthesis of single-walled carbon nanotubes selectively suspended on tips of vertically aligned silicon nanostructures fabricated by hydrogen plasma etching

    Here we present a method to synthesize single-walled carbon nanotubes (SWNTs) selectively suspended on tips of silicon-based nanostructure (Si-ns) templates. The Si-ns templates vertically aligned to the substrates are fabricated via an anisotropic etch process using reactive hydrogen plasmas, in which the etch-resistive nanomasks are the nanosized particles formed by thermal annealing of multi-layered catalytic thin films. After plasma etching, the nanosized self-masks remaining at the tips of the Si-ns directly serve as the catalysts for SWNT growth by thermal chemical vapour deposition. Consequently, the synthesized SWNTs are selectively suspended on the tips of the Si-ns, as revealed by characterizations using scanning electron microscopy and resonance Raman spectroscopy. This methodology provides a simple and straightforward approach to assemble two different nanomaterials, i.e., Si-ns and suspended SWNTs, together as a building block for constructing nanodevices for possible applications

  4. Direct Solvent-Derived Polymer-Coated Nitrogen-Doped Carbon Nanodots with High Water Solubility for Targeted Fluorescence Imaging of Glioma.

    Wang, Yi; Meng, Ying; Wang, Shanshan; Li, Chengyi; Shi, Wei; Chen, Jian; Wang, Jianxin; Huang, Rongqin

    2015-08-01

    Cancer imaging requires biocompatible and bright contrast-agents with selective and high accumulation in the tumor region but low uptake in normal tissues. Herein, 1-methyl-2-pyrrolidinone (NMP)-derived polymer-coated nitrogen-doped carbon nanodots (pN-CNDs) with a particle size in the range of 5-15 nm are prepared by a facile direct solvothermal reaction. The as-prepared pN-CNDs exhibit stable and adjustable fluorescence and excellent water solubility. Results of a cell viability test (CCK-8) and histology analysis both demonstrate that the pN-CNDs have no obvious cytotoxicity. Most importantly, the pN-CNDs can expediently enter glioma cells in vitro and also mediate glioma fluorescence imaging in vivo with good contrast via elevated passive targeting. PMID:25808813

  5. Hydrogen peroxide biosensor based on the direct electrochemistry of myoglobin immobilized on ceria nanoparticles coated with multiwalled carbon nanotubes by a hydrothermal synthetic method

    A novel myoglobin-based electrochemical biosensor was developed. It is based on a nanocomposite prepared from multiwalled carbon nanotubes that were coated with ceria nanoparticles. UV-vis and electrochemical measurements displayed that the nanocomposite provides a biocompatible matrix for the immobilization of myoglobin (Mb) and also facilitates direct electron transfer between its active center and the surface of the electrode. Immobilized Mb exhibits excellent electrocatalytic activity toward the reduction of hydrogen peroxide (HP). The low apparent Michaelis-Menten constant of 63. 3 μM indicates high bioactivity and enhanced affinity to HP. This study also shows that the nanocomposite is a promising support for immobilization of proteins and for the preparation of third-generation biosensors. (author)

  6. Direct and indirect effects of single walled carbon nanotubes on RAW 264.7 macrophages: role of iron.

    Kagan, V E; Tyurina, Y Y; Tyurin, V A; Konduru, N V; Potapovich, A I; Osipov, A N; Kisin, E R; Schwegler-Berry, D; Mercer, R; Castranova, V; Shvedova, A A

    2006-08-01

    Single-walled carbon nanotubes (SWCNT), nano-cylinders with an extremely small diameter (1-2 nm) and high aspect ratio, have unique physico-chemical, electronic and mechanical properties and may exhibit unusual interactions with cells and tissues, thus necessitating studies of their toxicity and health effects. Manufactured SWCNT usually contain significant amounts of iron that may act as a catalyst of oxidative stress. Because macrophages are the primary responders to different particles that initiate and propagate inflammatory reactions and oxidative stress, we utilized two types of SWCNT: (1) iron-rich (non-purified) SWCNT (26 wt.% of iron) and (2) iron-stripped (purified) SWCNT (0.23 wt.% of iron) to study their interactions with RAW 264.7 macrophages. Ultrasonication resulted in predominantly well-dispersed and separated SWCNT strands as evidenced by scanning electron microscopy. Neither purified nor non-purified SWCNT were able to generate intracellular production of superoxide radicals or nitric oxide in RAW 264.7 macrophages as documented by flow-cytometry and fluorescence microscopy. SWCNT with different iron content displayed different redox activity in a cell-free model system as revealed by EPR-detectable formation of ascorbate radicals resulting from ascorbate oxidation. In the presence of zymosan-stimulated RAW 264.7 macrophages, non-purified iron-rich SWCNT were more effective in generating hydroxyl radicals (documented by EPR spin-trapping with 5,5-dimethyl-1-pyrroline-N-oxide, DMPO) than purified SWCNT. Similarly, EPR spin-trapping experiments in the presence of zymosan-stimulated RAW 264.7 macrophages showed that non-purified SWCNT more effectively converted superoxide radicals generated by xanthine oxidase/xanthine into hydroxyl radicals as compared to purified SWCNT. Iron-rich SWCNT caused significant loss of intracellular low molecular weight thiols (GSH) and accumulation of lipid hydroperoxides in both zymosan-and PMA-stimulated RAW 264

  7. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    Alexandre, A.; Balesdent, J.; Cazevieille, P.; Chevassus-Rosset, C.; Signoret, P.; Mazur, J.-C.; Harutyunyan, A.; Doelsch, E.; Basile-Doelsch, I.; Miche, H.; Santos, G. M.

    2015-12-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the

  8. Direct uptake of organically derived carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    Alexandre, Anne; Balesdent, Jérôme; Cazevieille, Patrick; Chevassus-Rosset, Claire; Signoret, Patrick; Mazur, Jean-Charles; Harutyunyan, Araks; Doelsch, Emmanuel; Basile-Doelsch, Isabelle; Miche, Hélène; Santos, Guaciara M.

    2016-03-01

    In the rhizosphere, the uptake of low-molecular-weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relative to total uptake is important, organic C uptake is supposed to be low relative to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and to what extent organically derived C absorbed by grass roots can feed the C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled amino acids (AAs) to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C excess and 15N excess) in the roots, stems and leaves as well as phytoliths were measured relative to a control experiment in which no labeled AAs were added. Additionally, the 13C excess was measured at the molecular level, in AAs extracted from roots and stems and leaves. The net uptake of labeled AA-derived 13C reached 4.5 % of the total AA 13C supply. The amount of AA-derived 13C fixed in the plant was minor but not nil (0.28 and 0.10 % of total C in roots and stems/leaves, respectively). Phenylalanine and methionine that were supplied in high amounts to the nutritive solution were more 13C-enriched than other AAs in the plant. This strongly suggested that part of AA-derived 13C was absorbed and translocated into the plant in its original AA form. In phytoliths, AA-derived 13C was detected. Its concentration was on the same order of magnitude as in bulk stems and leaves (0.15 % of the phytolith C). This finding strengthens the body of evidences showing that part of organic compounds occluded in phytoliths can be fed by C entering the plant through the roots. Although this experiment was done in

  9. Design and evaluation of a high temperature/pressure supercritical carbon dioxide direct tubular receiver for concentrating solar power applications

    Ortega, Jesus Daniel

    This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923--973 K) and pressures (20--25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of 923 K at 25 MPa or 973 K at 20 MPa to meet the operating needs. To obtain compatible receiver tube material, an extensive material review was performed based the ASME Boiler and Pressure Vessel Code, ASME B31.1 and ASME B313.3 codes respectively. Subsequently, a thermal-structural model was developed using a commercial computational fluid (CFD) dynamics and structural mechanics software for designing and analyzing the tubular receiver that could provide the heat input for a ~2 MWth plant. These results were used to perform an analytical cumulative damage creep-fatigue analysis to estimate the work-life of the tubes. In sequence, an optical-thermal-fluid model was developed to evaluate the resulting thermal efficiency of the tubular receiver from the NSTTF heliostat field. The ray-tracing tool SolTrace was used to obtain the heat-flux distribution on the surfaces of the receiver. The K-ω SST turbulence model and P-1 radiation model used in Fluent were coupled with SolTrace to provide the heat flux distribution on the receiver surface. The creep-fatigue analysis displays the damage accumulated due to the cycling and the permanent deformation of the tubes. Nonetheless, they are able to support the required lifetime. The receiver surface temperatures were found to be within the safe

  10. Electrochemical oxidation of sodium borohydride on carbon supported Pt-Zn nanoparticle bimetallic catalyst and its implications to direct borohydride-hydrogen peroxide fuel cell

    Highlights: • The Pt-Zn/C catalyst as anode catalyst for DBHFC were facilely synthesized. • The average particle size of Pt-Zn bimetallic nanoparticles is approximately 2.5 nm. • The Zn-doping can apparently improve the catalytic activity for BH4− electrochemical oxidation. • The maximum power density of DBHFC employing Pt-Zn/C as anode catalyst is as high as 79.9 mW cm−2 at 79.5 mA cm−2 and 25 °C. - Abstract: Carbon supported Pt-Zn bimetallic nanoparticle electrocatalysts (Pt-Zn/C) are facilely prepared by a modified NaBH4 reduction method in aqueous solution at room temperature and investigated as alternative anode catalysts for direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared nanospherical electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and fuel cell test. Based on results of TEM and XRD, the Pt-Zn nanoparticles show average particle size of approximately 2.5 nm on the carbon surface. The fundamental electrochemical results show that the Pt-Zn/C catalysts exhibit much higher catalytic activity and stability for the direct oxidation of BH4− than Pt/C catalyst since Pt atoms are partly substituted by Zn atoms in Pt-Zn catalyst. Among various Pt-Zn catalysts with different compositions, the Pt67Zn33/C catalyst presents the highest catalytic activity for BH4− electrooxidation. The DBHFC using Pt67Zn33/C as anode catalyst and Pt/C as cathode catalyst obtains the maximum power density as high as 79.9 mW cm−2 at 79.5 mA cm−2 and 25 °C

  11. Controlling the Direction of the Molecular Axis of Rod-Shaped Binuclear Ruthenium Complexes on Single-Walled Carbon Nanotubes.

    Ozawa, Hiroaki; Kosaka, Kazuma; Kita, Tomomi; Yoshikawa, Kai; Haga, Masa-aki

    2016-05-01

    We report the synthesis of a mixed-valence ruthenium complex, bearing pyrene moieties on one side of the ligands as anchor groups. Composites consisting of mixed-valence ruthenium complexes and SWNTs were prepared by noncovalent π-π interactions between the SWNT surface and the pyrene anchors of the Ru complex. In these composites, the long axis of the Ru complexes was aligned in parallel to the principal direction of the SWNT. The optimized conformation of these complexes on the SWNT surface was calculated by molecular mechanics. The composites were examined by UV/Vis absorption and FT-IR spectroscopy, XPS, and SEM analysis. Furthermore, their electrochemical properties were evaluated. Cyclic voltammograms of the composites showed reversible oxidation waves at peak oxidation potentials (Epox ) = 0.86 and 1.08 V versus Fc(+) /Fc, which were assigned to the Ru(II) -Ru(II) /Ru(II) -Ru(III) and the Ru(II) -Ru(III) /Ru(III) -Ru(III) oxidation events of the dinuclear ruthenium complex, respectively. Based on these observations, we concluded that the electrochemical properties and mixed-valence state of the dinuclear ruthenium complexes were preserved upon attachment to the SWNT surface. PMID:27010865

  12. Facile one-step direct electrodeposition of bismuth nanowires on glassy carbon electrode for selective determination of folic acid

    Highlights: • BiNWs prepared through simple, fast one step electrochemical route. • BiNWs showed more catalytic activity and sensitivity than GC towards FA reduction. • Selective detection of FA was achieved with low limit of detection (9.53 × 10−9 mol L−1). • Real sample analysis was successfully demonstrated using FA pharmaceutical tablets. • BiNWs based sensor matrix is inexpensive, and more suitable for FA real application. - Abstract: In the present work, we have developed a facile one step route to electrodeposition of stabilizer-free bismuth nanowires (BiNWs) on glassy carbon (GC) substrates by using a simple potentiostatic method. Formation of BiNWs on GC substrate was confirmed by field emission scanning electron microscopy (FE-SEM). The growth of BiNWs on the GC substrate was monitored by cyclic voltammetry and found that continuous in-situ generation of hydrogen bubbles during electrodeposition provides a stagnant template for the formation of BiNWs on the GC substrate. Phase-purity of the deposited BiNWs on GC substrate studied by XRD indicates no other oxide formation. The electrodeposited BiNWs on GC substrate was used for electro-reduction of folic acid (FA) and its quantitative determination in Britton-Robinson buffer of pH 4.5 solutions. The observed cyclic voltammetric reduction current of FA on BiNWs/GC is almost 15 times higher with 0.015 V less negative overpotential compared to bare GC substrate alone. This result clearly reveals the electrocatalytic activity of the deposited BiNWs. In addition, square wave voltammetry (SWV) showed a perfectly linear response in the concentration range of 1 × 10−8–15 × 10−8 mol L−1 with a correlation coefficient of 0.9956. The limit of detection (LOD) and limit of quantitation (LOQ) are determined to be 9.53 × 10−9 and 31.68 × 10−9 mol L−1 respectively. The response of the BiNWs/GC sensor matrix is not affected by any usual interference from excess concentrations of metal ions

  13. 3 V omni-directionally stretchable one-body supercapacitors based on a single ion–gel matrix and carbon nanotubes

    Kim, Wonbin; Kim, Woong

    2016-06-01

    Stretchable supercapacitors often have laminated structures consisting of electrode, electrolyte, and supporting layers. Since the layers are likely to be composed of different materials, delamination is a major cause of failure upon stretching. In this study, we demonstrate delamination-free stretchable supercapacitors where all the component layers are prepared with a single matrix, which is composed of a polymer, poly(vinylidene fluoride-hexafluoropropylene) and an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Since the ionic liquid in the composite plays a role as both an electrolyte and a plasticizer, this composite can be used as an electrolyte and a supporting layer in the stretchable supercapacitor. The electrode layer can be fabricated by incorporating carbon nanotubes in the common matrix. Then, all the layers can be seamlessly fused into one body by dissolving the surface of the composite with acetone, which evaporates after the integration, leaving no borders between the layers. This one-body stretchable supercapacitor not only has high durability against repetitive stretches but also is stretchable in all directions. This feature clearly distinguishes them from conventional stretchable supercapacitors fabricated using buckled structures, which are stretchable only in one or two directions. Moreover, this supercapacitor has high cell voltage (∼3 V) owing to the ionic liquid-based gel electrolytes. Our demonstration of isotropically stretchable high-durability supercapacitors may have a great implication in the development of stretchable energy storage devices for real applications.

  14. Three-dimensional carbon- and binder-free nickel nanowire arrays as a high-performance and low-cost anode for direct hydrogen peroxide fuel cell

    Ye, Ke; Guo, Fen; Gao, Yinyi; Zhang, Dongming; Cheng, Kui; Zhang, Wenping; Wang, Guiling; Cao, Dianxue

    2015-12-01

    A novel three-dimensional carbon- and binder-free nickel nanowire arrays (Ni NAs) electrode is successfully fabricated by a facile galvanostatic electrodeposition method using polycarbonate membrane as the template. The Ni NAs electrode achieves a oxidation current density (divided by the electroactive surface areas of Ni) of 25.1 mA cm-2 in 4 mol L-1 KOH and 0.9 mol L-1 H2O2 at 0.2 V (vs. Ag/AgCl) accompanied with a desirable stability, which is significantly higher than the catalytic activity of H2O2 electro-oxidation achieved previously with precious metals as catalysts. The impressive electrocatalytic performance is largely attributed to the superior 3D open structure and high electronic conductivity, which ensures the high utilization of Ni surfaces and makes the electrode have higher electrochemical activity. The apparent activation energy of H2O2 electro-oxidation on the Ni NAs catalyst is 13.59 kJ mol-1. A direct peroxide-peroxide fuel cell using the Ni NAs as anode exhibits a peak power density of 48.7 mW cm-2 at 20 °C. The electrode displays a great promise as the anode of direct peroxide-peroxide fuel cell due to its low cost, high activity and stability.

  15. Electrical transport properties of single wall carbon nanotube/polyurethane composite based field effect transistors fabricated by UV-assisted direct-writing technology

    We report on the fabrication and transport properties of single-walled carbon nanotube (SWCNT)/polyurethane (PU) nanocomposite microfiber-based field effect transistors (FETs). UV-assisted direct-writing technology was used, and microfibers consisting of cylindrical micro-rods, having different diameters and various SWCNT loads, were fabricated directly onto SiO2/Si substrates in a FET scheme. The room temperature dc electrical conductivities of these microfibers were shown to increase with respect to the SWCNT concentrations in the nanocomposite, and were about ten orders of magnitude higher than that of the pure polyurethane, when the SWCNT load ranged from 0.1 to 2.5 wt% only. Our results show that for SWCNT loads ≤ 1.5 wt%, all the microfibers behave as a FET with p-type transport. The resulting FET exhibited excellent performance, with an Ion/Ioff ratio of 105 and a maximum on-state current (Ion) exceeding 70 µA. Correlations between the FET performance, SWCNTs concentration, and the microfiber diameters are also discussed. (paper)

  16. Direct electrochemistry of glucose oxidase and sensing glucose using a screen-printed carbon electrode modified with graphite nanosheets and zinc oxide nanoparticles

    We have studied the direct electrochemistry of glucose oxidase (GOx) immobilized on electrochemically fabricated graphite nanosheets (GNs) and zinc oxide nanoparticles (ZnO) that were deposited on a screen printed carbon electrode (SPCE). The GNs/ZnO composite was characterized by using scanning electron microscopy and elemental analysis. The GOx immobilized on the modified electrode shows a well-defined redox couple at a formal potential of −0.4 V. The enhanced direct electrochemistry of GOx (compared to electrodes without ZnO or without GNs) indicates a fast electron transfer at this kind of electrode, with a heterogeneous electron transfer rate constant (Ks) of 3.75 s−1. The fast electron transfer is attributed to the high conductivity and large edge plane defects of GNs and good conductivity of ZnO-NPs. The modified electrode displays a linear response to glucose in concentrations from 0.3 to 4.5 mM, and the sensitivity is 30.07 μA mM−1 cm−2. The sensor exhibits a high selectivity, good repeatability and reproducibility, and long term stability. (author)

  17. Electrospinning Directly Synthesized Porous TiO2 Nanofibers Modified by Graphitic Carbon Nitride Sheets for Enhanced Photocatalytic Degradation Activity under Solar Light Irradiation.

    Adhikari, Surya Prasad; Awasthi, Ganesh Prasad; Kim, Han Joo; Park, Chan Hee; Kim, Cheol Sang

    2016-06-21

    We report a direct approach to the fabrication of a composite made of porous TiO2 nanofibers (NFs) and graphitic carbon nitride (g-C3N4) sheets, by means of an angled two-nozzle electrospinning combined with calcination process. Different wt % amounts of g-C3N4 particles in a polymer solution from one nozzle and TiO2 precursors containing the same polymer solution from another nozzle were electrospun and deposited on the collector. Structural characterizations confirm a well-defined morphology of the TiO2/g-C3N4 composite in which the TiO2 NFs are uniformly attached on the g-C3N4 sheet. This proper attachment of TiO2 NFs on the g-C3N4 sheets occurred during calcination. The prepared composites showed the enhanced photocatalytic activity over the photodegradation of rhodamine B and reactive black 5 under natural sunlight. Here, the synergistic effect between the g-C3N4 sheets and the TiO2 NFs having anisotropic properties enhanced the photogenerated electron-hole pair separation and migration, which was confirmed by the measurement of photoluminescence spectra, cyclic voltammograms, and electrochemical impedance spectra. The direct synthesis approach that is established here for such kinds of sheetlike structure and porous NFs composites could provide new insights for the design of high-performance energy conversion catalysts. PMID:27254544

  18. Direct Coupling of Cs{sub 2}CO{sub 3} and Alcohols for the Synthesis of Dimethyl, Diethyl, and Various Dialkyl Carbonates

    Lim, Yu Na; Wang, Xi; Park, Eunjin; Jang, Hyeyoung [Ajou Univ., Suwon (Korea, Republic of)

    2014-02-15

    An efficient and high-yield synthesis for DMC has been actively investigated. Reaction conditions typically involve either carbon monoxide (CO) or derivatives (e. g., phosgene), or carbon dioxide (CO{sub 2}) or derivatives (e. g., inorganic carbonates or organic cyclic carbonates). Due to the toxicity and flammability of CO and phosgene, the more environmentally benign and sustainable carbon sources CO{sub 2} and derivatives have been actively employed for production of DMC and related acyclic carbonates. The DMC and acyclic carbonate syntheses that have been reported include: 1) transesterification of cyclic carbonates derived from oxirane and CO{sub 2}; 2) dehydrative condensation of alcohols with CO{sub 2}; 3) reactions between alkyl halide and metal carbonates; 4) reactions between alcohol, alkyl halide, and CO{sub 2}; and 5) reactions between alcohol and CO{sub 2} in the presence of condensing agents.

  19. A time-dependent direct current potential drop method to evaluate thickness of an oxide layer formed naturally and thermally on a large surface of carbon steel

    This study describes the use of a time-dependent spring-loaded four-point-probe technique to measure the direct current potential drop (DCPD) on oxidized test surfaces for different spring force values, with the purpose of evaluating the thickness of the oxide layer. The force of the spring attached to the current probe was reduced by inserting spacers with different thicknesses under the supporting legs of the sensor block. The PD measurement was first performed on machined sample exposed to the atmosphere for approximately 6 months. The sample was made of carbon steel (SS400). Then, the thickness of the oxide layer formed on the surface of the sample was increased by heat treatment. The PD was also measured on the samples subjected to heat treatment. The measurements were performed at different locations on the test surface under the same experimental conditions. The experimental results establish a relationship between the spring force and the time required for the current probe to penetrate the oxide layer. This article also proposes a procedure for evaluating the thickness of the oxide layer. Finally, the proposed method was used to evaluate the thickness of the oxide layer formed on a large surface. The method was performed to evaluate thickness of single phase monolayer oxide in the range of 3.5–8.7 μm. To demonstrate the validity and accuracy of the proposed method, the obtained thickness was compared to the thickness measured directly using a field emission scanning electron microscopy. - Highlights: ► Four-point-probe direct current potential drop technique. ► Naturally and thermally formed oxide layer on a large metallic surface. ► A procedure for evaluation of thickness of oxide layer formed on hot-rolled steel.

  20. Supercapacitor electrodes by direct growth of multi-walled carbon nanotubes on Al: a study of performance versus layer growth evolution

    Supercapacitor electrodes were fabricated by direct growth of multi-walled carbon nanotubes (CNTs) on Al current collectors via a chemical vapor deposition process in the presence of a spin-coated Co-Mo catalyst. A detailed study of the dependence of the CNT layer structure and thickness on growth time set the basis for the assessment of supercapacitors assembled with the CNTs/Al electrodes. As the main features of the layer growth evolution, an increase in the population of finer CNTs and a shift from a random entanglement to a rough vertical alignment of nanotubes were noted with proceeding growth. The growth time influence on the performance of supercapacitors was in fact apparent. Particularly, the specific capacitance of CNTs/Al electrodes in 0.5 M K2SO4 aqueous electrolyte increased from 35 to 80 F g−1 as the CNT layer thickness varied from 20 to 60 μm, with a concurrent loss in rate capability (knee frequency from 1 kHz to 60 Hz). The latter was excellent in general, arguably due to both a fast ion transport through the interconnected CNT network and a negligible contribution of the active layer/current collector contact to the equivalent series resistance (0.15–0.22 mΩ g), a distinct advantage of the direct growth fabrication method. Overall, a relatively simple process of direct growth of CNTs on Al foils is shown to be an effective method to fabricate supercapacitor electrodes, notably in the absence of special measures and processing steps finalized to a tight control of nanotubes growth and organization

  1. Renewable energy and the role of molten salts and carbon

    Fray D.

    2013-01-01

    Molten carbonate fuel cells have been under development for a number of years and reliable units are successfully working at 250kW scale and demonstration units have produced up to 2 MW. Although these cells cannot be considered as renewable as the fuel, hydrogen or carbon monoxide is consumed and not regenerated, the excellent reliability of such a cell can act as a stimulus to innovative development of similar cells with different outcomes. Molten salt electrolytes based upon LiCl - L...

  2. Improving the direct electron transfer in monolithic bioelectrodes prepared by immobilization of FDH enzyme on carbon-coated anodic aluminum oxide films

    Alberto eCastro-Muñiz

    2016-02-01

    Full Text Available The present work reports the preparation of binderless carbon-coated porous films and the study of their performance as monolithic bioanodes. The films were prepared by coating anodic aluminum oxide (AAO films with a thin layer of nitrogen-doped carbon by chemical vapor deposition. The films have cylindrical straight pores with controllable diameter and length. These monolithic films were used directly as bioelectrodes by loading the films with D-fructose dehydrogenase (FDH, an oxidoreductase enzyme that catalyzes the oxidation of D-fructose to 5-keto-D-fructose. The immobilization of the enzymes was carried out by physical adsorption in liquid phase and with an electrostatic attraction method. The latter method takes advantage of the fact that FDH is negatively charged during the catalytic oxidation of fructose. Thus the immobilization was performed under the application of a positive voltage to the CAAO film in a FDH-fructose solution in McIlvaine buffer (pH 5 at 25 ºC. As a result, the FDH modified electrodes with the latter method show much better electrochemical response than that with the conventional physical adsorption method. Due to the singular porous structure of the monolithic films, which consists of an array of straight and parallel nanochannels, it is possible to rule out the effect of the diffusion of the D-fructose into the pores. Thus the improvement in the performance upon using the electrostatic attraction method can be ascribed not only to a higher uptake, but also to a more appropriate molecule orientation of the enzyme units on the surface of the electrodes.

  3. Improving the direct electron transfer in monolithic bioelectrodes prepared by immobilization of FDH enzyme on carbon-coated anodic aluminum oxide films

    Castro-Muñiz, Alberto; Hoshikawa, Yasuto; Komiyama, Hiroshi; Nakayama, Wataru; Itoh, Tetsuji; Kyotani, Takashi

    2016-02-01

    The present work reports the preparation of binderless carbon-coated porous films and the study of their performance as monolithic bioanodes. The films were prepared by coating anodic aluminum oxide (AAO) films with a thin layer of nitrogen-doped carbon by chemical vapor deposition. The films have cylindrical straight pores with controllable diameter and length. These monolithic films were used directly as bioelectrodes by loading the films with D-fructose dehydrogenase (FDH), an oxidoreductase enzyme that catalyzes the oxidation of D-fructose to 5-keto-D-fructose. The immobilization of the enzymes was carried out by physical adsorption in liquid phase and with an electrostatic attraction method. The latter method takes advantage of the fact that FDH is negatively charged during the catalytic oxidation of fructose. Thus the immobilization was performed under the application of a positive voltage to the CAAO film in a FDH-fructose solution in McIlvaine buffer (pH 5) at 25 ºC. As a result, the FDH modified electrodes with the latter method show much better electrochemical response than that with the conventional physical adsorption method. Due to the singular porous structure of the monolithic films, which consists of an array of straight and parallel nanochannels, it is possible to rule out the effect of the diffusion of the D-fructose into the pores. Thus the improvement in the performance upon using the electrostatic attraction method can be ascribed not only to a higher uptake, but also to a more appropriate molecule orientation of the enzyme units on the surface of the electrodes.

  4. Electrochemical synthesis of belt-like polyaniline network on p-phenylenediamine functionalized glassy carbon electrode and its use for the direct electrochemistry of horse heart cytochrome c

    Zhang Lei, E-mail: chemzl@shnu.edu.c [Department of Chemistry, College of Life and Environment Sciences, Shanghai Normal University, Guilin RD 100, Shanghai 200234 (China); Shi Zhige; Lang Qiuhua; Pan Jie [Department of Chemistry, College of Life and Environment Sciences, Shanghai Normal University, Guilin RD 100, Shanghai 200234 (China)

    2010-01-01

    Three-dimension (3D) belt-like polyaniline (PAN) network has been prepared via electrochemical polymerization of aniline on p-phenylenediamine (PDA) functionalized glassy carbon electrode (GCE) using a three-step electrochemical deposition procedure. PDA was covalently binded on GCE via the formation of carbon-nitrogen bond between amine cation radical and the aromatic moiety of GCE surface using electrochemical oxidation procedure. X-ray photo-electron spectroscopy (XPS) and cyclic voltammetry have been performed to characterize the attachment of PDA on GCE. The images of scanning electron microscope (SEM) show that the 3D belt-like PAN network is uniform. The width and thickness of the PAN belt varies in the range of 1.5-5.5 mum and 0.1-0.8 mum, respectively. The distance between the belt-contacts ranges from 2.5 to 15 mum. The 3D belt-like PAN network modified GCE (PAN-PDA/GCE) exhibits an improved electro-activity of PAN at an extended pH up to 7.0. The PAN-PDA/GCE not only immobilizes but also leads to a direct electrochemical behavior of cytochrome c (Cyt c). The immobilized Cyt c maintains its activity, showing a surface-controlled electrode process with the electron-transfer rate constant (k{sub s}) of 14.8 s{sup -1} and electron-transfer coefficient (alpha) of 0.48, and could be used for the electrocatalytic reduction of hydrogen peroxide (H{sub 2}O{sub 2}).

  5. Optical properties of diamond like carbon films containing copper, grown by high power pulsed magnetron sputtering and direct current magnetron sputtering: Structure and composition effects

    Meškinis, Š., E-mail: sarunas.meskinis@ktu.lt; Čiegis, A.; Vasiliauskas, A.; Šlapikas, K.; Tamulevičius, T.; Tamulevičienė, A.; Tamulevičius, S.

    2015-04-30

    In the present study chemical composition, structure and optical properties of hydrogenated diamond like carbon films containing copper (DLC:Cu films) deposited by reactive magnetron sputtering were studied. Different modes of deposition — direct current (DC) sputtering and high power pulsed magnetron sputtering (HIPIMS) as well as two configurations of the magnetron magnetic field (balanced and unbalanced) were applied. X-ray diffractometry, Raman scattering spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy were used to study the structure and composition of the films. It was shown that by using HIPIMS mode contamination of the cathode during the deposition of DLC:Cu films can be suppressed. In all cases oxygen atomic concentration in the films was in 5–10 at.% range and it increased with the copper atomic concentration. The highest oxygen content was observed in the films deposited employing low ion/neutral ratio balanced DC magnetron sputtering process. According to the analysis of the parameters of Raman scattering spectra, sp{sup 3}/sp{sup 2} bond ratio decreased with the increase of Cu atomic concentration in the DLC films. Clear dependence of the extinction, absorbance and reflectance spectra on copper atomic concentration in the films was observed independently of the method of deposition. Surface plasmon resonance effect was observed only when Cu atomic concentration in DLC:Cu film was at least 15 at.%. The maximum of the surface plasmon resonance peak of the absorbance spectra of DLC:Cu films was in 600–700 nm range and redshifted with the increase of Cu amount. The ratio between the intensities of the plasmonic peak and hydrogenated amorphous carbon related peak at ~ 220 nm both in the extinction and absorbance spectra as well as peak to background ratio of DLC:Cu films increased linearly with Cu amount in the investigated 0–40 at.% range. Reflectance of the plasmonic DLC:Cu films was in 30–50% range that could be

  6. Optical properties of diamond like carbon films containing copper, grown by high power pulsed magnetron sputtering and direct current magnetron sputtering: Structure and composition effects

    In the present study chemical composition, structure and optical properties of hydrogenated diamond like carbon films containing copper (DLC:Cu films) deposited by reactive magnetron sputtering were studied. Different modes of deposition — direct current (DC) sputtering and high power pulsed magnetron sputtering (HIPIMS) as well as two configurations of the magnetron magnetic field (balanced and unbalanced) were applied. X-ray diffractometry, Raman scattering spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscopy were used to study the structure and composition of the films. It was shown that by using HIPIMS mode contamination of the cathode during the deposition of DLC:Cu films can be suppressed. In all cases oxygen atomic concentration in the films was in 5–10 at.% range and it increased with the copper atomic concentration. The highest oxygen content was observed in the films deposited employing low ion/neutral ratio balanced DC magnetron sputtering process. According to the analysis of the parameters of Raman scattering spectra, sp3/sp2 bond ratio decreased with the increase of Cu atomic concentration in the DLC films. Clear dependence of the extinction, absorbance and reflectance spectra on copper atomic concentration in the films was observed independently of the method of deposition. Surface plasmon resonance effect was observed only when Cu atomic concentration in DLC:Cu film was at least 15 at.%. The maximum of the surface plasmon resonance peak of the absorbance spectra of DLC:Cu films was in 600–700 nm range and redshifted with the increase of Cu amount. The ratio between the intensities of the plasmonic peak and hydrogenated amorphous carbon related peak at ~ 220 nm both in the extinction and absorbance spectra as well as peak to background ratio of DLC:Cu films increased linearly with Cu amount in the investigated 0–40 at.% range. Reflectance of the plasmonic DLC:Cu films was in 30–50% range that could be important in

  7. Photoelectrocatalytic decomposition of ethylene using TiO2/activated carbon fiber electrode with applied pulsed direct current square-wave potential

    Highlights: • Ethylene was decomposed by a photoelectrocatalytic (PEC) process. • A pulsed direct current square-wave (PDCSW) potential was applied to the PEC cell. • An electrode of TiO2 or modified TiO2 and activated carbon fiber (ACF) was used. • TiO2/ACF photocatalyst electrodes were modified by gamma radiolysis. • Efficiencies of the PEC process were higher than those of the process using DC. - Abstract: Removing ethylene (C2H4) from the atmosphere of storage facilities for fruits and vegetable is one of the main challenges in their postharvest handling for maximizing their freshness, quality, and shelf life. In this study, we investigated the photoelectrocatalytic (PEC) degradation of ethylene gas by applying a pulsed direct current DC square-wave (PDCSW) potential and by using a Nafion-based PEC cell. The cell utilized a titanium dioxide (TiO2) photocatalyst or γ-irradiated TiO2 (TiO2*) loaded on activated carbon fiber (ACF) as a photoelectrode. The apparent rate constant of a pseudo-first-order reaction (K) was used to describe the PEC degradation of ethylene. Parameters of the potential applied to the PEC cell in a reactor that affect the degradation efficiency in terms of the K value were studied. These parameters were frequency, duty cycle, and voltage. Ethylene degradation by application of a constant PDCSW potential to the PEC electrode of either TiO2/ACF cell or TiO2*/ACF cell enhanced the efficiency of photocatalytic degradation and PEC degradation. Gamma irradiation of TiO2 in the electrode and the applied PDCSW potential synergistically increased the K value. Independent variables (frequency, duty cycle, and voltage) of the PEC cell fabricated from TiO2 subjected 20 kGy γ radiation were optimized to maximize the K value by using response surface methodology with quadratic rotation–orthogonal composite experimental design. Optimized conditions were as follows: 358.36 Hz frequency, 55.79% duty cycle, and 64.65 V voltage. The maximum K

  8. Integrating the Carbon and Water Footprints’ Costs in the Water Framework Directive 2000/60/EC Full Water Cost Recovery Concept: Basic Principles Towards Their Reliable Calculation and Socially Just Allocation

    Anastasia Papadopoulou; Stavroula Tsitsifli; Vasilis Kanakoudis

    2012-01-01

    This paper presents the basic principles for the integration of the water and carbon footprints cost into the resource and environmental costs respectively, taking the suggestions set by the Water Framework Directive (WFD) 2000/60/EC one step forward. WFD states that full water cost recovery (FWCR) should be based on the estimation of the three sub-costs related: direct; environmental; and resource cost. It also strongly suggests the EU Member States develop and apply effective water pricing ...

  9. Direct electron transfer of glucose oxidase and dual hydrogen peroxide and glucose detection based on water-dispersible carbon nanotubes derivative

    Highlights: • Dual hydrogen peroxide and glucose sensor. • Direct electrochemistry of glucose oxidase used MWCNT-Py/GC electrode. • Change sensing function by adjusting pH value. - Abstract: A water-dispersible multi-walled carbon nanotubes (MWCNTs) derivative, MWCNTs-1-one-dihydroxypyridine (MWCNTs-Py) was synthesis via Friedel–Crafts chemical acylation. Raman spectra demonstrated the conjugated level of MWCNTs-Py was retained after this chemical modification. MWCNTs-Py showed dual hydrogen peroxide (H2O2) and glucose detections without mutual interference by adjusting pH value. It was sensitive to H2O2 in acidic solution and displayed the high performances of sensitivity, linear range, response time and stability; meanwhile it did not respond to H2O2 in neutral solution. In addition, this positively charged MWCNTs-Py could adsorb glucose oxidase (GOD) by electrostatic attraction. MWCNTs-Py-GOD/GC electrode showed the direct electron transfer (DET) of GOD with a pair of well-defined redox peaks, attesting the bioactivity of GOD was retained due to the non-destroyed immobilization. The high surface coverage of active GOD (3.5 × 10−9 mol cm−2) resulted in exhibiting a good electrocatalytic activity toward glucose. This glucose sensor showed high sensitivity (68.1 μA mM−1 cm−2) in a linear range from 3 μM to 7 mM in neutral buffer solution. The proposed sensor could distinguish H2O2 and glucose, thus owning high selectivity and reliability

  10. Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

    Saadati, Shagayegh [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman; Rostami, Amin [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2012-11-13

    Highlights: Black-Right-Pointing-Pointer Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. Black-Right-Pointing-Pointer First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation. Black-Right-Pointing-Pointer With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. Black-Right-Pointing-Pointer Immobilized catalase shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Black-Right-Pointing-Pointer Biosensor response is directly correlated to the number of bilayers. - Abstract: A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH{sub 2}-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH{sub 2}-IL and negatively charged catalase a sensitive H{sub 2}O{sub 2} biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k{sub s}) and Michaelis-Menten constant (K{sub M}) of immobilized catalase were 3.32 Multiplication-Sign 10{sup -12} mol cm{sup -2}, 5.28 s{sup -1} and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 {mu}A mM{sup -1} cm{sup -2} and low detection limit of 100 nM at concentration range up to 2.1 mM.

  11. Direct electron transfer of glucose oxidase and dual hydrogen peroxide and glucose detection based on water-dispersible carbon nanotubes derivative

    Chen, Hsiao-Chien [Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, 250, Wuxing St., Taipei 11031, Taiwan (China); Tu, Yi-Ming; Hou, Chung-Che [Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Tao-Yuan 33302, Taiwan (China); Lin, Yu-Chen [Wah Hong industrial Co. Ltd., 6 Lixing St., Guantian Dist., Tainan City 72046,Taiwan (China); Chen, Ching-Hsiang [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, 43 Keelung Rd., Sec. 4, Taipei 10607, Taiwan (China); Yang, Kuang-Hsuan, E-mail: khy@mail.vnu.edu.tw [Department of Food and Beverage Management, Vanung University, 1, Van Nung Rd., Shuei-Wei Li, Chung-Li City 32061, Taiwan (China)

    2015-03-31

    Highlights: • Dual hydrogen peroxide and glucose sensor. • Direct electrochemistry of glucose oxidase used MWCNT-Py/GC electrode. • Change sensing function by adjusting pH value. - Abstract: A water-dispersible multi-walled carbon nanotubes (MWCNTs) derivative, MWCNTs-1-one-dihydroxypyridine (MWCNTs-Py) was synthesis via Friedel–Crafts chemical acylation. Raman spectra demonstrated the conjugated level of MWCNTs-Py was retained after this chemical modification. MWCNTs-Py showed dual hydrogen peroxide (H{sub 2}O{sub 2}) and glucose detections without mutual interference by adjusting pH value. It was sensitive to H{sub 2}O{sub 2} in acidic solution and displayed the high performances of sensitivity, linear range, response time and stability; meanwhile it did not respond to H{sub 2}O{sub 2} in neutral solution. In addition, this positively charged MWCNTs-Py could adsorb glucose oxidase (GOD) by electrostatic attraction. MWCNTs-Py-GOD/GC electrode showed the direct electron transfer (DET) of GOD with a pair of well-defined redox peaks, attesting the bioactivity of GOD was retained due to the non-destroyed immobilization. The high surface coverage of active GOD (3.5 × 10{sup −9} mol cm{sup −2}) resulted in exhibiting a good electrocatalytic activity toward glucose. This glucose sensor showed high sensitivity (68.1 μA mM{sup −1} cm{sup −2}) in a linear range from 3 μM to 7 mM in neutral buffer solution. The proposed sensor could distinguish H{sub 2}O{sub 2} and glucose, thus owning high selectivity and reliability.

  12. Key Technologies of Using Renewable Energy to Capture Carbon from Ambient Air Directly%新能源驱动的从空气中直接捕碳的关键技术

    黎灿兵; 王煌; 耿英会; 孙良; 曹一家; 石海清

    2014-01-01

    Reducing the content of carbon dioxide in air is the key to addressing climate change.Carbon capture and storage is an important measure to reduce carbon dioxide emission.Capturing carbon from ambient air directly needs large amounts of energy.The loads on carbon capture devices are flexible,which to some extent can be driven by intermittent energy. Renewable energy such as wind power and solar energy has great potential for development,which has the characteristics of fluctuation.Using renewable energy to capture carbon from ambient air directly can reduce the concentration of carbon dioxide in the atmosphere.It is a promising way to address global climate change.This paper analyzes the potential of using renewable energy to capture carbon from ambient air directly,and proposes the key technologies of using renewable energy to capture carbon.The planning of using renewable energy to capture carbon is preliminarily studied,and the development trend of carbon capture driven by renewable energy is discussed.%降低空气中二氧化碳的含量是应对气候变化的关键。碳捕集与封存是减少二氧化碳排放量的重要措施。从空气中直接捕碳需要消耗大量能源。捕碳装置负荷是柔性负荷,可以在一定程度上接受波动性能源驱动。风能、太阳能等新能源开发潜力巨大,具有波动性的特点。利用其驱动捕碳装置从空气中直接捕碳,可以降低大气中二氧化碳的浓度,可望成为解决全球气候变化问题的关键途径。文中分析了利用新能源驱动的从空气中直接捕碳的潜力,提出了新能源捕碳的关键技术。对新能源捕碳的规划进行了初步研究,并对利用新能源捕碳的发展趋势进行了展望。

  13. Key Technologies of Using Renewable Energy to Capture Carbon from Ambient Air Directly%新能源驱动的从空气中直接捕碳的关键技术

    黎灿兵; 王煌; 耿英会; 孙良; 曹一家; 石海清

    2014-01-01

    降低空气中二氧化碳的含量是应对气候变化的关键。碳捕集与封存是减少二氧化碳排放量的重要措施。从空气中直接捕碳需要消耗大量能源。捕碳装置负荷是柔性负荷,可以在一定程度上接受波动性能源驱动。风能、太阳能等新能源开发潜力巨大,具有波动性的特点。利用其驱动捕碳装置从空气中直接捕碳,可以降低大气中二氧化碳的浓度,可望成为解决全球气候变化问题的关键途径。文中分析了利用新能源驱动的从空气中直接捕碳的潜力,提出了新能源捕碳的关键技术。对新能源捕碳的规划进行了初步研究,并对利用新能源捕碳的发展趋势进行了展望。%Reducing the content of carbon dioxide in air is the key to addressing climate change.Carbon capture and storage is an important measure to reduce carbon dioxide emission.Capturing carbon from ambient air directly needs large amounts of energy.The loads on carbon capture devices are flexible,which to some extent can be driven by intermittent energy. Renewable energy such as wind power and solar energy has great potential for development,which has the characteristics of fluctuation.Using renewable energy to capture carbon from ambient air directly can reduce the concentration of carbon dioxide in the atmosphere.It is a promising way to address global climate change.This paper analyzes the potential of using renewable energy to capture carbon from ambient air directly,and proposes the key technologies of using renewable energy to capture carbon.The planning of using renewable energy to capture carbon is preliminarily studied,and the development trend of carbon capture driven by renewable energy is discussed.

  14. A glucose biosensor based on direct electron transfer of glucose oxidase immobilized onto glassy carbon electrode modified with nitrophenyl diazonium salt

    Graphical abstract: - Abstract: This study reports a novel, simple and fast approach for construction of a highly stable glucose biosensor based on the immobilization of glucose oxidase (GOx) onto a glassy carbon electrode (GCE) electrografted with 4-aminophenyl (AP) by diazonium chemistry. Aminophenyl was used as cross-linker for covalent attachment of glucose oxidase to the electrode surface. Cyclic voltammograms of the GOx-modified GCE in phosphate buffer solution exhibited a pair of well-defined redox peaks, attesting the direct electron transfer (DET) of GOx with the underlying electrode. The proposed biosensor could be used to detect glucose based on the consumption of O2 with the oxidation of glucose catalyzed by GOx and exhibited a wide linear range of glucose from 0.05 mM to 4.5 mM and low detection limit of 10 μM. The surface coverage of active GOx, heterogeneous electron transfer rate constant (ks) and Michaelis–Menten constant (KM) of immobilized GOx were 1.23 × 10−12 mol cm−2, 4.25 s−1 and 2.95 mM, respectively. The great stability of this biosensor, technically simple and possibility of preparation at short period of time make this method suitable for fabrication of low-cost glucose biosensors

  15. Direct Electrochemistry of Glucose Oxidase Immobilized on Chitosan-gold Nanoparticle Composite Film on Glassy Carbon Electrodes and Its Biosensing Application

    2008-01-01

    The direct electrochemistry of glucose oxidase (Gox) immobilized on a composite matrix based on chitosan (CHIT) and Au nanoparticles (Au NP) underlying on a glassy carbon electrode was achieved. The cyclic voltam-metry and electrochemical impedance spectroscopy were used to characterize the modified electrode. In deaerated buffer solutions, the cyclic voltammetry of the composite films of Gox-Au NP-CHIT showed a pair of well-behaved redox peaks that were assigned to the redox reaction of Gox, confirming the effective immobilization of Gox on the composite film. The electron transfer rate constant was estimated to be 15.6 s-1, indicating a high electron transfer between the Gox redox center and electrode. The combination of CHIT and Au NP also promoted the stability of Gox in the composite film and retained its bioactivity, which might have the potential application to glucose determination. The calculated apparent Michaelis-Menten constant was 10.1 mmol·L-1. Furthermore, the proposed biosensor could be used for the determination of glucose in human plasma samples.

  16. Photothermal response of CVD synthesized carbon (nano)spheres/aqueous nanofluids for potential application in direct solar absorption collectors: a preliminary investigation.

    Poinern, Gérrard Eddy Jai; Brundavanam, Sridevi; Shah, Monaliben; Laava, Iafeta; Fawcett, Derek

    2012-01-01

    Direct-absorption solar collectors have the potential to offer an unlimited source of renewable energy with minimal environmental impact. Unfortunately, their performance is limited by the absorption efficiency of the working fluid. Nanoparticles of functionalized carbon nanospheres (CNS) have the potential to improve the photothermal properties of the working fluid. CNS are produced by the pyrolysis of acetylene gas in a tube-based electric furnace/chemical vapor deposition apparatus. The reaction takes place at 1000°C in the presence of nitrogen gas without the use of a catalyst. The synthesized CNS were examined and characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectroscopy, Raman spectroscopy, thermal gravimetric analysis, and ultraviolet-visible analysis. The CNS powders with a mean particle size of 210 nm were then functionalized using tetraethylammonium hydroxide ([C2H5]4 N[OH]) and used to produce a series of aqueous nanofluids with varying mass content. The photothermal response of both the nanofluids and films composed of CNS were investigated under 1000 W/m(2) solar irradiation. PMID:24198496

  17. Highly effective and CO-tolerant PtRu electrocatalysts supported on poly(ethyleneimine) functionalized carbon nanotubes for direct methanol fuel cells

    A highly efficient and CO tolerant PtRu electrocatalysts supported on amino-rich, cationic poly(ethyleneimine) polyelectrolyte functionalized multi-walled carbon nanotubes (PtRu/PEI-MWCNTs) has been developed. The catalysts were characterized by thermogravimetric analysis, Raman spectroscopy, cyclic voltammograms, CO stripping, chronoamperometry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The PtRu particles with average size ∼2.5 nm are well dispersed on PEI-MWCNTs. The peak current for the methanol oxidation reaction on 40% PtRu/PEI-MWCNTs is 636mAmgPt−1, 5.7 times higher than 112mA mgPt−1 measured on the 40% PtRu supported on acid treated MWCNTs (PtRu/AO-MWCNTs) under identical conditions. PtRu/PEI-MWCNTs catalysts exhibit a superior electrocatalytic activity and stability for the methanol oxidation reaction due to its high tolerance toward CO poisoning as compared with PtRu/AO-MWCNTs for direct methanol fuel cells

  18. Influence of calcination temperature on the morphology and energy storage properties of cobalt oxide nanostructures directly grown over carbon cloth substrates

    Rakhi, R. B.

    2013-09-23

    Nanostructured and mesoporous cobalt oxide (Co3O4) nanowire in flower-like arrangements have been directly grown over flexible carbon cloth collectors using solvothermal synthesis for supercapacitor applications. Changes in the morphology and porosity of the nanowire assemblies have been induced by manipulating the calcination temperature (200–300 °C) of the one-dimensional (1-D) structures, resulting in significant impact on their surface area and pseudocapacitive properties. As the calcination temperature increases from 200 to 250 °C, the flower morphology gradually modifies to the point where the electrolyte could access almost all the nanowires over the entire sample volume, resulting in an increase in specific capacitance from 334 to 605 Fg−1, depending on the nanowire electrode morphology. The 300 °C calcination results in the breakdown of the mesoporous morphology and decreases the efficiency of electrolyte diffusion, resulting in a drop in pseudocapacitance after 300 °C. A peak energy density of 44 Wh kg−1 has been obtained at a power density of 20 kW kg−1 for the 250 °C calcined sample.

  19. Enhanced direct electron transfer reactivity of hemoglobin in cationic gemini surfactant-room temperature ionic liquid composite film on glassy carbon electrodes

    A novel composite film comprising cationic gemini surfactant butyl-α,ω-bis(dimethylcetylammonium bromide) (C16H33N(CH3)2-C4H8-N(CH3)2C16H33, C16-C4-C16) and ionic liquid 1-octyl-3-methylimidazolium hexafluorophate (OMIMPF6) has been prepared. The composite film shows good biocompatibility and it can promote the direct electron transfer between hemoglobin (Hb) and glassy carbon (GC) electrode. On the C16-C4-C16 (dissolved in ethanol)-OMIMPF6 film coated GC electrode, the immobilized Hb can exhibit a pair of well-defined, quasi-reversible and stable redox peaks with a formal potential of -0.317 V (vs SCE) in 0.10 M pH 7 phosphate buffer solutions. The electron transfer coefficient (α) of Hb is calculated to be 0.44 and the heterogeneous electron transfer rate constant is 6.08 s-1. With the length of alkyl chains of gemini surfactant increasing and the ethanol concentration rising, the redox peaks of the resulting electrode C16-C4-C16-OMIMPF6-Hb/GC become bigger. The electrode presents good electrocatalytic response to peroxide hydrogen. The kinetic parameters Imax and km for the catalytic reaction are estimated. In addition, UV-vis spectra and reflectance absorption infrared spectra demonstrate that the Hb immobilized in the C16-C4-C16-OMIMPF6 film almost retains the structure of native Hb

  20. 直读光谱法测定超低碳钢板的碳含量%Determination of Carbon in Steel Sheets of Ultra-Low Carbon Content by Direct-Reading Atomic Emission Spectrography

    李吉; 牟正明; 包雪鹏; 孙国燕

    2014-01-01

    用一系列含碳量(wC )在0.002%~0.03%范围内的标准物质在直读光谱仪上按选定的工作条件测定各样品的碳量。根据所得每一样品的一系列测定值以及各项统计量,分析并判断了直读光谱法在测定钢板中超低碳含量的准确度和精密度水平。试验结果表明:①测定结果的准确度受样品的基体背景及仪器标准化条件的影响,引入了系统误差;据此建议选择与待测样品基体匹配的标准物质校准仪器并选择合理的仪器标准化条件。②在上述含碳量范围内,所得测定值的S%值(包括10次测定和5次测定的计算值)差异较小,其极值之差为3×10-4%,但对相对标准偏差有显著影响,其最低值在2%左右,而最高值达21%。③在所选定的测定条件下,对碳含量在10-5数量级的样品而言,准确度或系统误差的波动范围在±1×10-4%范围内。%A set of CRM′s with values of wC% ranged from 0.002% to 0.03% was analyzed for their carbon contents with a direct reading AES under the specified working conditions.A statistical study was made based on data obtained,i.e.,the values ofwC% of each of the CRM′s and their statistics and levels of accuracy and precision of the method for determination of ultra-low carbon in steel sheets were assessed.It was shown that:① accuracy of the analytical results was affected by the matrix background of individual sample and standardization condition of the instrument,it is advised to choose CRM′s having similar composition with the sample for calibration of instrument and rational condition of standardization;② in the range of carbon content concerned,only small differences among values of S% (either for n=5 or 10)were obtained with difference of extreme values of 3×10-4 %,but significant differences of values of RSD% were observed with min.and max.values of 2% and 21% respectively;and ③ range of fluctuation of systematic

  1. 直读光谱法测定超低碳钢板的碳含量%Determination of Carbon in Steel Sheets of Ultra-Low Carbon Content by Direct-Reading Atomic Emission Spectrography

    李吉; 牟正明; 包雪鹏; 孙国燕

    2014-01-01

    A set of CRM′s with values of wC% ranged from 0.002% to 0.03% was analyzed for their carbon contents with a direct reading AES under the specified working conditions.A statistical study was made based on data obtained,i.e.,the values ofwC% of each of the CRM′s and their statistics and levels of accuracy and precision of the method for determination of ultra-low carbon in steel sheets were assessed.It was shown that:① accuracy of the analytical results was affected by the matrix background of individual sample and standardization condition of the instrument,it is advised to choose CRM′s having similar composition with the sample for calibration of instrument and rational condition of standardization;② in the range of carbon content concerned,only small differences among values of S% (either for n=5 or 10)were obtained with difference of extreme values of 3×10-4 %,but significant differences of values of RSD% were observed with min.and max.values of 2% and 21% respectively;and ③ range of fluctuation of systematic error (or of accuracy)for determination of carbon content at the magnitude of 10-5 attained to values ranged in ±1×10-4 %.%用一系列含碳量(wC )在0.002%~0.03%范围内的标准物质在直读光谱仪上按选定的工作条件测定各样品的碳量。根据所得每一样品的一系列测定值以及各项统计量,分析并判断了直读光谱法在测定钢板中超低碳含量的准确度和精密度水平。试验结果表明:①测定结果的准确度受样品的基体背景及仪器标准化条件的影响,引入了系统误差;据此建议选择与待测样品基体匹配的标准物质校准仪器并选择合理的仪器标准化条件。②在上述含碳量范围内,所得测定值的S%值(包括10次测定和5次测定的计算值)差异较小,其极值之差为3×10-4%,但对相对标准偏差有显著影响,其最低值在2%左右,而最高值达21%。③在所选定的测

  2. Enhanced direct electron transfer reactivity of hemoglobin in cationic gemini surfactant-room temperature ionic liquid composite film on glassy carbon electrodes

    Li Jiangwen; Liu Lihong; Yan Rui; Xiao Mengying; Liu Liqin [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Zhao Faqiong [Department of Chemistry, Wuhan University, Wuhan 430072 (China)], E-mail: zhaofq@chem.edu.cn; Zeng Baizhao [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2008-05-20

    A novel composite film comprising cationic gemini surfactant butyl-{alpha},{omega}-bis(dimethylcetylammonium bromide) (C{sub 16}H{sub 33}N(CH{sub 3}){sub 2}-C{sub 4}H{sub 8}-N(CH{sub 3}){sub 2}C{sub 16}H{sub 33}, C{sub 16}-C{sub 4}-C{sub 16}) and ionic liquid 1-octyl-3-methylimidazolium hexafluorophate (OMIMPF{sub 6}) has been prepared. The composite film shows good biocompatibility and it can promote the direct electron transfer between hemoglobin (Hb) and glassy carbon (GC) electrode. On the C{sub 16}-C{sub 4}-C{sub 16} (dissolved in ethanol)-OMIMPF{sub 6} film coated GC electrode, the immobilized Hb can exhibit a pair of well-defined, quasi-reversible and stable redox peaks with a formal potential of -0.317 V (vs SCE) in 0.10 M pH 7 phosphate buffer solutions. The electron transfer coefficient ({alpha}) of Hb is calculated to be 0.44 and the heterogeneous electron transfer rate constant is 6.08 s{sup -1}. With the length of alkyl chains of gemini surfactant increasing and the ethanol concentration rising, the redox peaks of the resulting electrode C{sub 16}-C{sub 4}-C{sub 16}-OMIMPF{sub 6}-Hb/GC become bigger. The electrode presents good electrocatalytic response to peroxide hydrogen. The kinetic parameters I{sub max} and k{sub m} for the catalytic reaction are estimated. In addition, UV-vis spectra and reflectance absorption infrared spectra demonstrate that the Hb immobilized in the C{sub 16}-C{sub 4}-C{sub 16}-OMIMPF{sub 6} film almost retains the structure of native Hb.

  3. 中国OFDI推动低碳经济的路径构建%Path Construction of China's Outward Foreign Direct Investment for Pushing Forward Low-carbon Economy

    罗良文; 成晓杰

    2013-01-01

    This paper analyzes the relationship between China's outward foreign direct investment(OFDI)and the development of low-carbon economy,and constructs China's OFDI path to promote the development of low carbon economy.It considers that,with the low-carbon opportunity and requirement,Chinas OFDI should start from the motivation to guide the development of low-carbon economy and construct the low-carbon path from aspects of investment industry,location and entry mode.Concretely speaking,low-carbon investment helps to avoid carbon tariff and non-tariff barriers of developed countries cleverly,and get out from the plight of 'carbon emissions embodied in trade('),and obtain technology spillover.A global strategic framework should be built through cross-border M&A and international strategic alliance,which helps to not only enhance the level of OFDI in low-carbon economy,but also achieve a long-term development of low-carbon economy directed by OFDI.%深入分析了我国OFDI与低碳经济的关系,构建了我国OFDI推动低碳经济发展的路径:在低碳契机和低碳要求下,我国的OFDI应从投资动因出发,从投资产业、区位选择和进入方式方面建立低碳路径,引导低碳经济实现跨越式发展.具体而言:以低碳投资巧避发达国家的碳关税和非关税壁垒,用低碳投资化解“贸易隐含碳”的困境,在低碳投资中寻求技术溢出效应;采取跨国并购和国际战略联盟的方式建立低碳经济发展的全球战略框架,以树立低碳大国形象,既实现低碳经济背景下对外直接投资水平的提升,又促进低碳经济在OFDI的引导下实现长足发展.

  4. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CNx) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CNx films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N2/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, Vs, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at Vs ≥ 60 V, Vs ≥ 100 V, and Vs = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of Vs for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all Vs, while CNx films deposited by MFMS showed residual stresses up to −4.2 GPa. Nanoindentation showed a significant increase in film

  5. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    Bakoglidis, Konstantinos D., E-mail: konba@ifm.liu.se; Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  6. Direct measurement of carbon solubility in the intermetallic (Fe,Cr)2(Mo,W) Laves phase using atom-probe field-ion microscopy

    The (Fe,Cr)2(Mo,W) Laves phase found in the studied 10.5% chromium steel, which had been creep tested for nearly 1,500 h at 600 C, contained 0.8 at.% carbon. Thus, the solubility of carbon in this phase cannot be considered to be negligible. When compared with matrix analyses of the same material in the as-tempered state, the matrix surrounding the Laves phase in the creep tested material showed a slight enrichment in carbon. Besides carbon, Laves phase was enriched in silicon (3.7 at.%) and phosphorus (0.7 at.%). Further studies of the role of these elements on the nucleation and stability of Laves phase in 9%--12% chromium steels should be performed

  7. Direct Electrochemistry of Glucose Oxidase Immobilized on Surface of Activated Carbon%葡萄糖氧化酶在活性炭上的固定及直接电化学

    孙冬梅; 蔡称心; 邢巍; 陆天虹

    2005-01-01

    The glucose oxidase (GOD) immobilized onto the surface of activated carbon powders at the glassy carbon electrode (GOD-C/GC) could undergo the quasi-reversible, direct electrochemical reaction. Its formal redox potential, E0', is almost independent on the scan rates. The average value of E0' is (-0.467±0.002) V (vs SCE) in the pH 6.8 phosphate buffer solution. Its apparent heterogeneous electron transfer rate constant (ks) is (1.18±0.59) s-1, which is much higher than that reported previously. The dependence of E0' on the pH of the buffer solution indicated that the direct electrochemical reaction of the immobilized GOD is a two-electron transfer reaction process coupled with twoproton transfer. The further experimental results demonstrated that the immobilized GOD retained its bioelectrocatalytic activity to the oxidation of β-D(+) glucose.

  8. Triplex inducer-directed self-assembly of single-walled carbon nanotubes: a triplex DNA-based approach for controlled manipulation of nanostructures

    Zhao, Chao; Qu, Konggang; Xu, Can; Ren, Jinsong; Qu, Xiaogang

    2011-01-01

    As a promising strategy for artificially control of gene expression, reversible assembly of nanomaterials and DNA nanomachine, DNA triplex formation has received much attention. Carbon nanotubes as gene and drug delivery vector or as ‘building blocks’ in nano/microelectronic devices have been successfully explored. Therefore, studies on triplex DNA-based carbon nanotube hybrid materials are important for development of smart nanomaterials and for gene therapy. In this report, a small molecule...

  9. Evaluation of different dielectric barrier discharge plasma configurations as an alternative technology for green C1 chemistry in the carbon dioxide reforming of methane and the direct decomposition of methanol.

    Rico, Víctor J; Hueso, José L; Cotrino, José; González-Elipe, Agustín R

    2010-03-25

    Carbon dioxide reforming of methane and direct decomposition of methanol have been investigated using dielectric barrier discharges (DBD) at atmospheric pressure and reduced working temperatures. Two different plasma reactor configurations are compared and special attention is paid to the influence of the surface roughness of the electrodes on the conversion yields in the first plasma device. The influence of different filling gap dielectric materials (i.e., Al(2)O(3) or BaTiO(3)) in the second packed configuration has been also evaluated. Depending on the experimental conditions of applied voltage, residence time of reactants, feed ratios, or reactor configuration, different conversion yields are achieved ranging from 20 to 80% in the case of methane and 7-45% for the carbon dioxide. The direct decomposition of methanol reaches 60-100% under similar experimental conditions. Interestingly, the selectivity toward the production of hydrogen and carbon monoxide is kept almost constant under all the experimental conditions, and the formation of longer hydrocarbon chains or coke as a byproduct is not detected. The maximum efficiency yields are observed for the packed-bed reactor configuration containing alumina for both reaction processes (approximately 1 mol H(2) per kilowatt hour for dry reforming of methane and approximately 4.5 mol H(2) per kilowatt hour for direct decomposition of methanol). PMID:20184329

  10. A new model for electron flow during anaerobic digestion: direct interspecies electron transfer to Methanosaeta for the reduction of carbon dioxide to methane

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

    2013-01-01

    , coupled with fluorescence in situ hybridization with specific 16S rRNA probes, revealed that Methanosaeta species were the most abundant and metabolically active methanogens. Methanogens known to reduce carbon dioxide with H2 or formate as the electron donor were rare. Although Methanosaeta have...... carbon dioxide to methane. The discovery that Methanosaeta species, which are abundant in a wide diversity of methanogenic environments, are capable of DIET has important implications not only for the functioning of anaerobic digesters, but also for global methane production....... previously been thought to be restricted to acetate as a substrate for methane production, Methanosaeta in the aggregates had a complete complement of genes for the enzymes necessary for the reduction of carbon to methane, and transcript abundance for these genes was high. Furthermore, Geobacter species, the...

  11. Platinium Nanoparticles Deposited on Oxygen-Containing Functional Groups at Carbon Vulcane XC-72 as a Cathode Catalyst for Direct Methanol Fuel Cell

    Sajjad; Sadaghat; Sharehjini; Ahmad; Nozad; Golikand; Mohammad; Yari

    2007-01-01

    1 Results Surface oxidized carbon vulcane XC-72 as catalyst support, prepared by chemically anchoring Pt onto the surface modified carbon vulcane XC-72. The nanoparticles of Pt are synthesized by reduction of H2PtCl6 with sodium borohydride in a 5.5 buffer solution of sodium citrate, the complexation of citrate with metal ions is beneficial to the formation of nanoparticles. For comparison, an electrode is prepared by E-Tek Pt/C 20 Wt% with a typical Pt loading of 50 μg·cm-2, that shows higher specifi...

  12. New Synthesis of Pt-Ru Nanoparticles on Surface Modified Carbon Vulcane XC-72 as an Effective Catalyst for Direct Methanol Fuel Cell

    Ahmad; Nozad; Golikand; Sajjad; Sadaghat; Sharehjini; Mohammad; Yari

    2007-01-01

    1 Results Pt-Ru nanoparticles are synthesised on the surface oxidized carbon Vulcane XC-72 as catalyst support by chemically anchoring Pt and Ru onto the surface of modified carbon vulcane XC-72 (by refluxing in 70% HNO3 at 120 ℃ for 12 h to introduce surface functional groups) .The nanoparticles of Pt and Ru are synthesized by reduction of H2PtCl6 and K4Ru(CN)6 with sodium borohydride in a 5.5 buffer solution of sodium citrate,the complexation of citrate with metal ions is beneficial to the formati...

  13. Directs measurement of high temperature/high pressure solubility of methane and carbon dioxide in polyamide (PA-11) using a high-pressure microbalance

    von Solms, Nicolas; Rubin, A; Andersen, Simon Ivar;

    2005-01-01

    Experiments to determine the Solubility of methane and carbon dioxide in PA-11 have been performed in the temperature range 50-90&DEG; C and the pressure ranges 50-150 bar for methane and 20-40 bar for carbon dioxide. In general, the results agree fairly well with previous experiments for similar...... polymers, as well as showing correct trends in terms of temperature and pressure. The Solubility of the gases follows Henry's law-type behavior except for methane at very high pressures. Diffusivities were also measured for the same systems at the same conditions. While the diffusivities are subject to...

  14. Novel CoS2 embedded carbon nanocages by direct sulfurizing metal-organic frameworks for dye-sensitized solar cells.

    Cui, Xiaodan; Xie, Zhiqiang; Wang, Ying

    2016-06-01

    Owing to its excellent electrocatalytic properties, cobalt disulfide (CoS2) is regarded as a promising counter electrode (CE) material for dye-sensitized solar cells (DSSCs). However, hindered by its relatively poor electrical conductivity and chemical instability, it remains a challenge to apply it into high-performance DSSCs. In this work, we have developed novel CoS2 embedded carbon nanocages as a CE in DSSCs, using ZIF-67 (zeolitic imidazolate framework 67, Co(mim)2, mim = 2-methylimidolate) as a template. The CoS2 samples sulfurized for different time lengths are prepared through a facile solution process. It is found that the sulfurization time can be optimized to maximize the DSSC efficiency and the DSSC based on the CoS2 embedded carbon nanocages sulfurized for 4 hours exhibits the highest photovoltaic conversion efficiency (PCE) of 8.20%, higher than those of DSSCs consisting of other CoS2 CEs and Pt-based DSSC (7.88%). The significantly improved DSSC PCE is contributed by the synergic effect of inner CoS2 nanoparticles and an amorphous carbon matrix, leading to a CE with high catalytic activity, good electrical conductivity and excellent durability. This study demonstrates that the CE based on inexpensive CoS2 embedded carbon nanocages is a prospective substitute to expensive platinum and provides a new approach for commercializing high-efficiency DSSCs. PMID:27240927

  15. Facile template-directed synthesis of carbon-coated SnO{sub 2} nanotubes with enhanced Li-storage capabilities

    Zhu, Xiaoshu; Zhu, Jingyi; Yao, Yinan; Zhou, Yiming; Tang, Yawen; Wu, Ping, E-mail: zjuwuping@njnu.edu.cn

    2015-08-01

    Herein, a novel type of carbon-coated SnO{sub 2} nanotubes has been designed and synthesized through a facile two-step hydrothermal approach by using ZnO nanorods as templates. During the synthetic route, SnO{sub 2} nanocrystals and carbon layer have been uniformly deposited on the rod-like templates in sequence, meanwhile ZnO nanorods could be in situ dissolved owing to the generated alkaline and acidic environments during hydrothermal coating of SnO{sub 2} nanocrystals and hydrothermal carbonization of glucose, respectively. When utilized as an anode material in lithium-ion batteries, the carbon-coated SnO{sub 2} nanotubes manifests markedly enhanced Li-storage capabilities in terms of specific capacity and cycling stability in comparison with bare SnO{sub 2} nanocrystals. - Graphical abstract: Display Omitted - Highlights: • C-coated SnO{sub 2} nanotubes prepared via facile ZnO-nanorod-templated hydrothermal route. • Unique morphological and structural features toward lithium storage. • Enhanced Li-storage performance in terms of specific capacity and cycling stability.

  16. Bottom-up electrochemical preparation of solid-state carbon nanodots directly from nitriles/ionic liquids using carbon-free electrodes and the applications in specific ferric ion detection and cell imaging.

    Niu, Fushuang; Xu, Yuanhong; Liu, Mengli; Sun, Jing; Guo, Pengran; Liu, Jingquan

    2016-03-14

    Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often required. Herein, solid-state C-dots were simply prepared by bottom-up EC carbonization of nitriles (e.g. acetonitrile) in the presence of an ionic liquid [e.g. 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6)], using carbon-free electrodes. Due to the positive charges of BMIM(+) on the C-dots, the final products presented in a precipitate form on the cathode, and the unreacted nitriles and BMIMPF6 can be easily removed by simple vacuum filtration. The as-prepared solid-state C-dots can be well dispersed in an aqueous medium with excellent photoluminescence properties. The average size of the C-dots was found to be 3.02 ± 0.12 nm as evidenced by transmission electron microscopy. Other techniques such as UV-vis spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy were applied for the characterization of the C-dots and to analyze the possible generation mechanism. These C-dots have been successfully applied in efficient cell imaging and specific ferric ion detection. PMID:26891173

  17. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    Alexandre, A.; Balesdent, J.; P. Cazevieille; C. Chevassus-Rosset; Signoret, P; J.-C. Mazur; Harutyunyan, A.; E. Doelsch; Basile-Doelsch, I.; H. Miche; Santos, G. M.

    2015-01-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in...

  18. CO2 sequestration using waste concrete and anorthosite tailings by direct mineral carbonation in gas-solid-liquid and gas-solid routes.

    Ben Ghacham, Alia; Cecchi, Emmanuelle; Pasquier, Louis-César; Blais, Jean-François; Mercier, Guy

    2015-11-01

    Mineral carbonation (MC) represents a promising alternative for sequestering CO2. In this work, the CO2 sequestration capacity of the available calcium-bearing materials waste concrete and anorthosite tailings is assessed in gas-solid-liquid and gas-solid routes using 18.2% flue CO2 gas. The objective is to screen for a better potential residue and phase route and as the ultimate purpose to develop a cost-effective process. The results indicate the possibility of removing 66% from inlet CO2 using waste concrete for the aqueous route. However, the results that were obtained with the carbonation of anorthosite were less significant, with 34% as the maximal percentage of CO2 removal. The difference in terms of reactivity could be explained by the accessibility to calcium. In fact, anorthosite presents a framework structure wherein the calcium is trapped, which could slow the calcium dissolution into the aqueous phase compared to the concrete sample, where calcium can more easily leach. In the other part of the study concerning gas-solid carbonation, the results of CO2 removal did not exceed 15%, which is not economically interesting for scaling up the process. The results obtained with waste concrete samples in aqueous phase are interesting. In fact, 34.6% of the introduced CO2 is converted into carbonate after 15 min of contact with the gas without chemical additives and at a relatively low gas pressure. Research on the optimization of the aqueous process using waste concrete should be performed to enhance the reaction rate and to develop a cost-effective process. PMID:26292776

  19. 旅游——中国低碳经济的发展方向%Tourism –Development Direction of Chinese Low Carbon Economy

    吴晓芳

    2012-01-01

    今后的竞争不是传统的劳动力竞争,也不是石油效率的竞争,而是碳生产率的竞争。综合考虑长远战略、现实竞争力、环境成本等因素,发展低碳经济不是高成本,而是具有竞争力的低成本。中国要低碳化,可以走发展旅游之路。%Future competition is neither the competition of traditional labor nor the competition of oil efficiency,but the competition of productivity of carbon.In integrative consideration of long term stratagem,realistic competitive power,cost of environment etc,it is not high cost to develop low carbon economy,but low cost with competitive power.If Chinawants to be low-carbonized,it is an option to develop tourism.

  20. 2-MW plasmajet facility thermal tests of concrete

    A test was made in the 2-Megawatt Plasmajet Facility to obtain experimental data relative to the thermal response of concrete to incident heat flux. 14.6 cm diameter by 8.0 cm long concrete cylinders were positioned in a supersonic flow of heated nitrogen from an arc heater. The end of the concrete cylinders impacted by the flow were subjected to heat fluxes in the range of 0.13 to 0.35 kW/cm2. Measurements included cold wall surface heat flux and pressure distributions, surface and indepth temperatures, ablation rates, and surface emission spectrographs. The test was part of the Sandia light water reactor safety research program and complements similar tests made in the Radiant Heat Facility at heat fluxes from 0.03 to 0.12 kW/cm2. A description of the tests and a tabulation of test data are included

  1. Solid-State 2MW Klystron Power Control System

    Kempkes, Michael; Gaudreau, Marcel; Hawkey, Timothy; Roth, Ian

    2005-01-01

    Under an SBIR effort for the DOE, Diversified Technologies, Inc. designed, built, and installed a solid state power control system for the Advanced Light Source klystrons at Argonne National Laboratory (ANL). This system consists of two major elements - a 100 kV, 20 A CW solid state series switch, and a solid state voltage regulator for the mod-anode of the klystron. The series switch replaces the existing mercury ignitron crowbar, eliminating these environmentally hazardous components while providing enhanced arc protection and faster return to transmit. The mod-anode voltage regulator uses series IGBTs, operating in the linear regime, to provide highly rapid and accurate control of the mod-anode voltage, and therefore the output power from the klystron. Results from the installation and testing of this system at ANL will be presented.

  2. Bottom-up electrochemical preparation of solid-state carbon nanodots directly from nitriles/ionic liquids using carbon-free electrodes and the applications in specific ferric ion detection and cell imaging

    Niu, Fushuang; Xu, Yuanhong; Liu, Mengli; Sun, Jing; Guo, Pengran; Liu, Jingquan

    2016-03-01

    Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often required. Herein, solid-state C-dots were simply prepared by bottom-up EC carbonization of nitriles (e.g. acetonitrile) in the presence of an ionic liquid [e.g. 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6)], using carbon-free electrodes. Due to the positive charges of BMIM+ on the C-dots, the final products presented in a precipitate form on the cathode, and the unreacted nitriles and BMIMPF6 can be easily removed by simple vacuum filtration. The as-prepared solid-state C-dots can be well dispersed in an aqueous medium with excellent photoluminescence properties. The average size of the C-dots was found to be 3.02 +/- 0.12 nm as evidenced by transmission electron microscopy. Other techniques such as UV-vis spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy were applied for the characterization of the C-dots and to analyze the possible generation mechanism. These C-dots have been successfully applied in efficient cell imaging and specific ferric ion detection.Carbon nanodots (C-dots), a new type of potential alternative to conventional semiconductor quantum dots, have attracted numerous attentions in various applications including bio-chemical sensing, cell imaging, etc., due to their chemical inertness, low toxicity and flexible functionalization. Various methods including electrochemical (EC) methods have been reported for the synthesis of C-dots. However, complex procedures and/or carbon source-containing electrodes are often

  3. Driving High-Performance n- and p-type Organic Transistors with Carbon Nanotube/Conjugated Polymer Composite Electrodes Patterned Directly from Solution

    Hellstrom, Sondra L.

    2010-07-12

    We report patterned deposition of carbon nanotube/conjugated polymer composites from solution with high nanotube densities and excellent feature resolution. Such composites are suited for use as electrodes in high-performance transistors of pentacene and C60, with bottom-contact mobilities of ?0.5 and ?1 cm2 V-1 s-1, respectively. This represents a clear step towards development of inexpensive, high-performance all-organic circuits. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Delving into the carbon footprints of Singapore-comparing direct and indirect greenhouse gas emissions of a small and open economic system

    Schulz, Niels B., E-mail: Schulz@iiasa.ac.a [International Institute for Applied Systems Analysis (IIASA), Program: Transition to New Technologies, Global Energy Assessment, Schlossplatz 1, 133 General purpose bldg. A-2361 Laxenburg (Austria); Imperial College London, Energy Futures Lab, 7B Bessemer Building, South Kensington Campus, SW7 2AZ (United Kingdom)

    2010-09-15

    Small and open economic systems like cities face specific challenges for greenhouse gas accounting. They typically import most of their energy requirements as secondary energy products based on conversion processes which caused emissions elsewhere. Emission estimates therefore already require attention not only to direct on-site activities. Moreover, for a comprehensive approach it is suggested to include upstream and downstream processes of connected socioeconomic systems and the indirect life-cycle related emissions of imported and exported goods. Singapore is used in this longitudinal study as an example of an urban scale economy. Accounts for direct emissions are compared with trade corrected estimates of indirect emissions. Results indicate that direct emissions account for only about 20% of the overall upstream emissions necessary to sustain the input side of the economic production process (domestic emissions plus indirect emissions embodied in imported goods). If indirect emissions embodied in exports are considered and subtracted from the previous figure, the trade corrected accounts for direct and indirect emissions still exceed direct emission accounts, although by less than 40%. Given the increasing trends in world trade and urbanisation, indirect pressures of urban systems should be included in discussions of effective and fair adaptation and mitigation strategies.

  5. Delving into the carbon footprints of Singapore. Comparing direct and indirect greenhouse gas emissions of a small and open economic system

    Schulz, Niels B. [International Institute for Applied Systems Analysis IIASA, Laxenburg (Austria)

    2010-09-15

    Small and open economic systems like cities face specific challenges for greenhouse gas accounting. They typically import most of their energy requirements as secondary energy products based on conversion processes which caused emissions elsewhere. Emission estimates therefore already require attention not only to direct on-site activities. Moreover, for a comprehensive approach it is suggested to include upstream and downstream processes of connected socioeconomic systems and the indirect life-cycle related emissions of imported and exported goods. Singapore is used in this longitudinal study as an example of an urban scale economy. Accounts for direct emissions are compared with trade corrected estimates of indirect emissions. Results indicate that direct emissions account for only about 20% of the overall upstream emissions necessary to sustain the input side of the economic production process (domestic emissions plus indirect emissions embodied in imported goods). If indirect emissions embodied in exports are considered and subtracted from the previous figure, the trade corrected accounts for direct and indirect emissions still exceed direct emission accounts, although by less than 40%. Given the increasing trends in world trade and urbanisation, indirect pressures of urban systems should be included in discussions of effective and fair adaptation and mitigation strategies. (author)

  6. Delving into the carbon footprints of Singapore-comparing direct and indirect greenhouse gas emissions of a small and open economic system

    Small and open economic systems like cities face specific challenges for greenhouse gas accounting. They typically import most of their energy requirements as secondary energy products based on conversion processes which caused emissions elsewhere. Emission estimates therefore already require attention not only to direct on-site activities. Moreover, for a comprehensive approach it is suggested to include upstream and downstream processes of connected socioeconomic systems and the indirect life-cycle related emissions of imported and exported goods. Singapore is used in this longitudinal study as an example of an urban scale economy. Accounts for direct emissions are compared with trade corrected estimates of indirect emissions. Results indicate that direct emissions account for only about 20% of the overall upstream emissions necessary to sustain the input side of the economic production process (domestic emissions plus indirect emissions embodied in imported goods). If indirect emissions embodied in exports are considered and subtracted from the previous figure, the trade corrected accounts for direct and indirect emissions still exceed direct emission accounts, although by less than 40%. Given the increasing trends in world trade and urbanisation, indirect pressures of urban systems should be included in discussions of effective and fair adaptation and mitigation strategies.

  7. A simple and sensitive method for lactose detection based on direct electron transfer between immobilised cellobiose dehydrogenase and screen-printed carbon electrodes

    Safina, Gulnara, E-mail: Gulnara.Safina@chem.gu.s [Department of Analytical Chemistry/Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden); Ludwig, Roland [Department of Analytical Chemistry/Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden); Research Centre Applied Biocatalysis, Petersgasse 18, 8010 Graz (Austria); Gorton, Lo, E-mail: Lo.Gorton@biochemistry.lu.s [Department of Analytical Chemistry/Biochemistry, Lund University, Box 124, 221 00 Lund (Sweden)

    2010-11-01

    A rapid and simple approach of lactose analysis is proposed based on 3rd generation amperometric biosensors employing cellobiose dehydrogenase (CDH) from Trametes villosa or Phanerochaete sordida immobilised on screen-printed carbon electrodes (SPCEs). After optimisation of the working conditions of the biosensors - pH of the carrier buffer, flow rate and applied potential - the sensors were able to detect lactose in a concentration range between 0.5-200 {mu}M and 0.5-100 {mu}M employing T. villosa and P. sordida CDH, respectively. The limit of detection is 250 nM (90 {mu}g/L) for both. Biosensors based on SPCEs modified with multiwalled carbon nanotubes showed a higher sensitivity than unmodified SPCEs. Cross-linking with glutaraldehyde or poly(ethyleneglycol)diglycidyl ether improved not only the stability but also the analytical response. The developed sensor has been successfully applied for the determination of lactose in dairy (milk with different percentages of fat, lactose-free milk and yogurt) with a good reproducibility (RSD = 1.5-2.2%). No sample preparation except a simple dilution process is needed. The biosensor is easy to make and operate, is inexpensive and reveals a high sensitivity and reliability.

  8. Interplay of Ion-Water and Water-Water Interactions within the Hydration Shells of Nitrate and Carbonate Directly Probed with 2D IR Spectroscopy.

    Fournier, Joseph A; Carpenter, William; De Marco, Luigi; Tokmakoff, Andrei

    2016-08-01

    The long-range influence of ions in solution on the water hydrogen-bond (H-bond) network remains a topic of vigorous debate. Recent spectroscopic and theoretical studies have, for the most part, reached the consensus that weakly coordinating ions only affect water molecules in the first hydration shell. Here, we apply ultrafast broadband two-dimensional infrared (2D IR) spectroscopy to aqueous nitrate and carbonate in neat H2O to study the solvation structure and dynamics of ions on opposite ends of the Hofmeister series. By exciting both the water OH stretches and ion stretches and probing the associated cross-peaks between them, we are afforded a comprehensive view into the complex nature of ion hydration. We show in aqueous nitrate that weak ion-water H-bonding leads to water-water interactions in the ion solvation shells dominating the dynamics. In contrast, the carbonate CO stretches show significant mixing with the water OH stretches due to strong ion-water H-bonding such that the water and ion modes are intimately correlated. Further, the excitonic nature of vibrations in neat H2O, which spans multiple water molecules, is an important factor in describing ion hydration. We attribute these complex dynamics to the likely presence of intermediate-range effects influenced by waters beyond the first solvation shell. PMID:27404015

  9. A simple and sensitive method for lactose detection based on direct electron transfer between immobilised cellobiose dehydrogenase and screen-printed carbon electrodes

    A rapid and simple approach of lactose analysis is proposed based on 3rd generation amperometric biosensors employing cellobiose dehydrogenase (CDH) from Trametes villosa or Phanerochaete sordida immobilised on screen-printed carbon electrodes (SPCEs). After optimisation of the working conditions of the biosensors - pH of the carrier buffer, flow rate and applied potential - the sensors were able to detect lactose in a concentration range between 0.5-200 μM and 0.5-100 μM employing T. villosa and P. sordida CDH, respectively. The limit of detection is 250 nM (90 μg/L) for both. Biosensors based on SPCEs modified with multiwalled carbon nanotubes showed a higher sensitivity than unmodified SPCEs. Cross-linking with glutaraldehyde or poly(ethyleneglycol)diglycidyl ether improved not only the stability but also the analytical response. The developed sensor has been successfully applied for the determination of lactose in dairy (milk with different percentages of fat, lactose-free milk and yogurt) with a good reproducibility (RSD = 1.5-2.2%). No sample preparation except a simple dilution process is needed. The biosensor is easy to make and operate, is inexpensive and reveals a high sensitivity and reliability.

  10. Integrating the Carbon and Water Footprints’ Costs in the Water Framework Directive 2000/60/EC Full Water Cost Recovery Concept: Basic Principles Towards Their Reliable Calculation and Socially Just Allocation

    Anastasia Papadopoulou

    2012-01-01

    Full Text Available This paper presents the basic principles for the integration of the water and carbon footprints cost into the resource and environmental costs respectively, taking the suggestions set by the Water Framework Directive (WFD 2000/60/EC one step forward. WFD states that full water cost recovery (FWCR should be based on the estimation of the three sub-costs related: direct; environmental; and resource cost. It also strongly suggests the EU Member States develop and apply effective water pricing policies to achieve FWCR. These policies must be socially just to avoid any social injustice phenomena. This is a very delicate task to handle, especially within the fragile economic conditions that the EU is facing today. Water losses play a crucial role for the FWC estimation. Water losses should not be neglected since they are one of the major “water uses” in any water supply network. A methodology is suggested to reduce water losses and the related Non Revenue Water (NRW index. An Expert Decision Support System is proposed to assess the FWC incorporating the Water and Carbon Footprint costs.

  11. Simultaneous determination of mercury and organic carbon using a direct mercury analyzer: Mercury profiles in sediment cores from oxbow lakes in the Mississippi Delta

    Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed for total-mercury (Hg) using a direct mercury analyzer (DMA). In the process we evaluated the feasibility of simultaneously determining organic matter content by...

  12. Poly(ethylene oxide)-b-poly(L-lactide) diblock copolymer/carbon nanotube-based nanocomposites: LiCl as supramolecular structure-directing agent.

    Meyer, Franck; Raquez, Jean-Marie; Verge, Pierre; Martínez de Arenaza, Inger; Coto, Borja; Van Der Voort, Pascal; Meaurio, Emilio; Dervaux, Bart; Sarasua, Jose-Ramon; Du Prez, Filip; Dubois, Philippe

    2011-11-14

    This work relies on the CNT dispersion in either solution or a polymer matrix through the formation of a three-component supramolecular system composed of PEO-b-PLLA diblock copolymer, carbon nanotubes (CNTs), and lithium chloride. According to a one-pot procedure in solution, the "self-assembly" concept has demonstrated its efficiency using suspension tests of CNTs. Characterizations of the supramolecular system by photon correlation spectroscopy, Raman spectroscopy, and molecular dynamics simulations highlight the charge transfer interaction from the CNTs toward the PEO-b-PLLA/LiCl complex. Finally, this concept was successfully extended in bulk (absence of solvent) via melt-processing techniques by dispersing these complexes in a commercial polylactide (PLA) matrix. Electrical conductivity measurements and transmission electron microscopy attested for the remarkable dispersion of CNTs, confirming the design of high-performance PLA-based materials. PMID:21936499

  13. Direct production of carbon nanofibers decorated with Cu2O by thermal chemical vapor deposition on Ni catalyst electroplated on a copper substrate

    MA Vesaghi

    2012-12-01

    Full Text Available  Carbon nanofibers (CNFs decorated with Cu2O particles were grown on a Ni catalyst layer deposited on a Cu substrate by thermal. chemical vapor deposition from liquid petroleum gas. Ni catalyst nanoparticles with different sizes were produced in an electroplating system at 35˚C. These nanoparticles provide the nucleation sites for CNF growth, removing the need for a buffer layer. High temperature surface segregation of the Cu substrate into the Ni catalyst layer and its exposition to O2 at atmospheric environment, during the CNFs growth, lead to the production of CNFs decorated with Cu2O particles. The surface morphology of the Ni catalyst films and grown CNFs over it was studied by scanning electron microscopy. Transmission electron microscopy and Raman spectroscopy revealed the formation of CNFs. The selected area electron diffraction pattern and electron diffraction studies show that these CNFs were decorated with Cu2O nanoparticles.

  14. Stable 'floating' air diffusion biocathode based on direct electron transfer reactions between carbon particles and high redox potential laccase

    Shleev, S. [Laboratory of Chemical Enzymology, A.N. Bach Institute of Biochemistry, Moscow (Russian Federation); Biomedical Laboratory Science, Health and Society, Malmoe University (Sweden); Shumakovich, G.; Morozova, O.; Yaropolov, A. [Laboratory of Chemical Enzymology, A.N. Bach Institute of Biochemistry, Moscow (Russian Federation)

    2010-08-15

    We report on the assembly and characterisation of a high potential, stable, mediator-less and cofactor free biocathode based on a fungal laccase (Lc), adsorbed on highly dispersed carbonaceous materials. First, the stability and activity of Trametes hirsuta Lc immobilised on different carbon particles were studied and compared to the solubilised enzyme. Based on the experimental results and a literature analysis, the carbonaceous material BM-4 was chosen to design efficient and stable biocatalysts for the production of a 'floating' air diffusion Lc-based biocathode. Voltammetric characteristics and operational stability of the biocathode were investigated. The current density of oxygen reduction at the motionless biocathode in a quiet, air saturated citrate buffer (100 mM, pH 4.5, 23 C) reached values as high as 0.3 mA cm{sup -2} already at 0.7 V versus NHE. The operational stability of the biocathode depended on the current density of the device. For example, at low current density (20 {mu}A cm{sup -2}), the biocathode lost only 5 x of its initial power after 1 month of continuous operation. However, when the device was polarised at 150 mV it lost more than 32 x of its initial power in just 10 min. We also found that co-immobilisation of Lc and peroxidase on highly dispersed carbon materials could protect the biocatalyst from rapid inactivation by hydrogen peroxide produced during electrocatalytic reactions at high-current densities. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  15. Hybrid Composites Based on Carbon Fiber/Carbon Nanofilament Reinforcement

    Mehran Tehrani; Ayoub Yari Boroujeni; Claudia Luhrs; Jonathan Phillips; Al-Haik, Marwan S.

    2014-01-01

    Carbon nanofilament and nanotubes (CNTs) have shown promise for enhancing the mechanical properties of fiber-reinforced composites (FRPs) and imparting multi-functionalities to them. While direct mixing of carbon nanofilaments with the polymer matrix in FRPs has several drawbacks, a high volume of uniform nanofilaments can be directly grown on fiber surfaces prior to composite fabrication. This study demonstrates the ability to create carbon nanofilaments on the surface of carbon fibers emplo...

  16. Photothermal response of CVD synthesized carbon (nano)spheres/aqueous nanofluids for potential application in direct solar absorption collectors: a preliminary investigation

    Poinern GE; Brundavanam S; Shah M; Laava I; Fawcett D

    2012-01-01

    Gérrard Eddy Jai Poinern,1 Sridevi Brundavanam,1 Monaliben Shah,1 Iafeta Laava,2 Derek Fawcett11Murdoch Applied Nanotechnology Research Group, 2Department of Physics, Energy Studies and Nanotechnology, Murdoch University, Perth, AustraliaAbstract: Direct-absorption solar collectors have the potential to offer an unlimited source of renewable energy with minimal environmental impact. Unfortunately, their performance is limited by the absorption efficiency of the working fluid. Nanop...

  17. Carbon fuel cells with carbon corrosion suppression

    Cooper, John F.

    2012-04-10

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

  18. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models. Current status and future directions

    Tian, Hanqin [Auburn Univ., AL (United States); Lu, Chaoqun [Auburn Univ., AL (United States); Yang, Jia [Auburn Univ., AL (United States); Banger, Kamaljit [Auburn Univ., AL (United States); Huntzinger, Deborah N. [Northern Arizona Univ., Flagstaff, AZ (United States); Schwalm, Christopher R. [Northern Arizona Univ., Flagstaff, AZ (United States); Michalak, A. M. [Carnegie Inst. for Science, Stanford, CA (United States); Cook, Robert B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ciais, Philippe [Climate and Environment Sciences Lab. (LSCE) (France); Hayes, Daniel J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Huang, Maoyi [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ito, Akihiko [National Inst. for Environmental Studies, Tsukuba (Japan); Jain, Atul K. [Univ. of Illinois, Urbana-Champaign, IL (United States); Lei, Huimin [Tsinghua Univ., Beijing (China); Mao, Jiafu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pan, Shufen [Auburn Univ., AL (United States); Post, W. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peng, Shushi [Climate and Environment Sciences Lab. (LSCE) (France); Poulter, Benjamin [Montana State Univ., Bozeman, MT (United States); Ren, Wei [Auburn Univ., AL (United States); Ricciuto, Daniel M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Schaefer, Kevin [National Snow and Ice Data Center, Boulder, CO (United States); Shi, Xiaoying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tao, Bo [Auburn Univ., AL (United States); Wang, Weile [National Aeronautics and Space Administration, Mountain View, CA (United States); Wei, Yaxing [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Qichun [Auburn Univ., AL (United States); Zhang, Bowen [Auburn Univ., AL (United States); Zeng, Ning [Univ. of Maryland, College Park, MD (United States)

    2015-06-05

    Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and loss from soil accounts for a large pro portion of land-atmosphere C exchange. Due to large pool size and variable residence time from years to millennia, even small changes in soil organic C(SOC) have substantial effects on the terrestrial C budget, thereby affecting atmospheric carbon dioxide (CO2)concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain and identifying major driving forces controlling soil C storage and fluxes remains a key research challenge his study has compiled century-long (1901-2010)estimates of SOC storage and heterotrophic respiration (Rh) from ten terrestrial biosphere models (TBMs) in the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) and two observation based datasets. The ten-TBM ensemble shows that global SOC estimate range from 4 to 2111 Pg C (1 Pg = 1015g) with a median value of 1158 Pg C33 in 2010. Modeling approach estimates a broad range of Rh from 35 to 69 Pg C yr-1 with a median value of 51Pg C yr-1 during 200–2010. The largest uncertainty in SOC stocks exists in the 40–65°N latitude band while Rh differences are the largest in the tropics. All the models agreed that climate and land use changes have decreased SOC stocks while elevated CO2 and atmospheric nitrogen deposition have increased SOC stocks though the response varied significantly among models. Model representations of temperature and moisture sensitivity,nutrient limitation and land use partially explain the divergent estimates of global SOC stocks and soil fluxes in this study. In addition, major sources of uncertainty from model estimation include exclusion of SOC storage in

  19. Chlorine and temperature directed self-assembly of Mg-Ru2(ii,iii) carbonates and particle size dependent magnetic properties.

    Yang, Jian-Hui; Cheng, Ru-Mei; Jia, Yan-Yan; Jin, Jin; Yang, Bing-Bing; Cao, Zhi; Liu, Bin

    2016-02-21

    A series of heterometallic magnesium diruthenium(ii,iii) carbonates, namely K{Mg(H2O)6}2[Ru2(CO3)4Cl2]·4H2O (1), K2[{Mg(H2O)4}2Ru2(CO3)4(H2O)Cl]Cl2·2H2O (2), K[Mg(H2O)5Ru2(CO3)4]·5H2O (3) and K[Mg(H2O)4Ru2(CO3)4]·H2O (4), were synthesized from the reaction of Ru2(CO3)4(3-) and Mg(2+) in aqueous solution. Compound 1 is composed of ionic crystals with the Ru2(CO3)4Cl2(5-) : Mg(H2O)6(2+) : K(+) ratio of 1 : 2 : 1. Compound 2 consists of two dimensional layer structures, in which each octahedral environment Mg(H2O)4(2+) bonds to two [Ru2(CO3)4(H2O)Cl](4-) units in a cis manner forming a neutral square-grid layer {Mg(H2O)4Ru2(CO3)4(H2O)Cl}n. For compound 3, one water molecule of each Mg(H2O)6(2+) is substituted by an oxygen atom of Ru2(CO3)4(3-) forming [Mg(H2O)5Ru2(CO3)4](-), and then the neighboring Ru2 dimers are linked together by the rest of the two oxygen atoms of carbonates to form a layer structure {Mg(H2O)5Ru2(CO3)4}n(n-). In compound 4, the neighboring squared-grid layers {Ru2(CO3)4}n(3n-), similar to those in compound 3, are linked by each octahedral environment Mg(H2O)4(2+) in a cis manner forming the three-dimensional network {Mg(H2O)4Ru2(CO3)4}n(n-). Compound 3 shows ferromagnetic coupling between Ru2 dimers, and a long-range ordering is observed below 3.8 K. Compound 4 displays a magnetic ordering below 3.5 K, and a systematic study of the size-dependent magnetic properties of compound 4 reveals that the coercivity of 4 has been improved with reduced sample particle size from the micrometer to the nanometer scale. PMID:26750871

  20. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models: Current status and future directions

    Tian, Hanqin; Lu, Chaoqun; Yang, Jia; Banger, Kamaljit; Huntzinger, Deborah N.; Schwalm, Christopher R.; Michalak, Anna M.; Cook, Robert; Ciais, Philippe; Hayes, Daniel; Huang, Maoyi; Ito, Akihiko; Jain, Atul K.; Lei, Huimin; Mao, Jiafu; Pan, Shufen; Post, Wilfred M.; Peng, Shushi; Poulter, Benjamin; Ren, Wei; Ricciuto, Daniel; Schaefer, Kevin; Shi, Xiaoying; Tao, Bo; Wang, Weile; Wei, Yaxing; Yang, Qichun; Zhang, Bowen; Zeng, Ning

    2015-06-01

    Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and C loss from soil accounts for a large proportion of land-atmosphere C exchange. Therefore, a small change in soil organic C (SOC) can affect atmospheric carbon dioxide (CO2) concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil C exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain, and identifying major driving forces controlling soil C dynamics remains a key research challenge. This study has compiled century-long (1901-2010) estimates of SOC storage and heterotrophic respiration (Rh) from 10 terrestrial biosphere models (TBMs) in the Multi-scale Synthesis and Terrestrial Model Intercomparison Project and two observation-based data sets. The 10 TBM ensemble shows that global SOC estimate ranges from 425 to 2111 Pg C (1 Pg = 1015 g) with a median value of 1158 Pg C in 2010. The models estimate a broad range of Rh from 35 to 69 Pg C yr-1 with a median value of 51 Pg C yr-1 during 2001-2010. The largest uncertainty in SOC stocks exists in the 40-65°N latitude whereas the largest cross-model divergence in Rh are in the tropics. The modeled SOC change during 1901-2010 ranges from -70 Pg C to 86 Pg C, but in some models the SOC change has a different sign from the change of total C stock, implying very different contribution of vegetation and soil pools in determining the terrestrial C budget among models. The model ensemble-estimated mean residence time of SOC shows a reduction of 3.4 years over the past century, which accelerate C cycling through the land biosphere. All the models agreed that climate and land use changes decreased SOC stocks, while elevated atmospheric CO2 and nitrogen deposition over intact ecosystems increased SOC stocks—even though the responses varied significantly among models. Model

  1. Reaction Mechanism for Direct Proton Transfer from Carbonic Acid to a Strong Base in Aqueous Solution II: Solvent Coordinate-Dependent Reaction Path.

    Daschakraborty, Snehasis; Kiefer, Philip M; Miller, Yifat; Motro, Yair; Pines, Dina; Pines, Ehud; Hynes, James T

    2016-03-10

    The protonation of methylamine base CH3NH2 by carbonic acid H2CO3 within a hydrogen (H)-bonded complex in aqueous solution was studied via Car-Parrinello dynamics in the preceding paper (Daschakraborty, S.; Kiefer, P. M.; Miller, Y.; Motro, Y.; Pines, D.; Pines, E.; Hynes, J. T. J. Phys. Chem. B 2016, DOI: 10.1021/acs.jpcb.5b12742 ). Here some important further details of the reaction path are presented, with specific emphasis on the water solvent's role. The overall reaction is barrierless and very rapid, on an ∼100 fs time scale, with the proton transfer (PT) event itself being very sudden (ion pair, stabilizing it by establishment of equilibrium solvation. The solvent water's short time scale ∼120 fs response to the incipient ion pair formation is primarily associated with librational modes and H-bond compression of water molecules around the carboxylate anion and the protonated base. This is consistent with this stabilization involving significant increase in H-bonding of hydration shell waters to the negatively charged carboxylate group oxygens' (especially the former H2CO3 donor oxygen) and the nitrogen of the positively charged protonated base's NH3(+). PMID:26876428

  2. Waste-Glycerol-Directed Synthesis of Mesoporous Silica and Carbon with Superior Performance in Room-Temperature Hydrogen Production from Formic Acid

    Lee, Dong-Wook; Jin, Min-Ho; Park, Ji Chan; Lee, Chun-Boo; Oh, Duckkyu; Lee, Sung-Wook; Park, Jin-Woo; Park, Jong-Soo

    2015-10-01

    The development of easier, cheaper, and more ecofriendly synthetic methods for mesoporous materials remains a challenging topic to commercialize them, and the transformation of waste glycerol, as a biodiesel byproduct, into something useful and salable is one of the pending issues to be resolved. Here we first report that mesoporous silica (KIE-6) and carbon (KIE-7) can be simultaneously synthesized by using cheap and ecofriendly crude-waste-glycerol of biodiesel with or without glycerol purification, and we demonstrated the excellent performance of the mesoporous material as a catalyst support for formic acid decomposition. As a result, Pd-MnOx catalysts supported on NH2-functionalized KIE-6 showed the highest catalytic activity (TOF: 540.6 h-1) ever reported for room-temperature formic acid decomposition without additives. Moreover, we conducted life-cycle assessment (LCA) from biomass cultivation through biodiesel production to KIE-6 and KIE-7 preparation, and it was confirmed that CO2 emission during synthesis of KIE-6 and KIE-7 could be reduced by 87.1% and 85.7%, respectively. We believe that our study suggested more ecofriendly and industry-friendly approaches for preparation of mesoporous materials, and utilization of waste glycerol.

  3. Direct electron transfer from native human hemoglobin using a glassy carbon electrode modified with chitosan and a poly(N,N-diethylacrylamide) hydrogel containing red blood cells

    We report on a new whole cell biosensor for hydrogen peroxide. A chitosan-coated glassy carbon electrode (GCE) was modified with poly(N,N-diethylacrylamide) (PDEA) hydrogel containing human red blood cells (RBCs). The morphology of RBCs in the hydrogel was investigated using scanning electron microscopy (SEM). Fourier transform infrared spectroscopy and SEM were applied to study the association of the PDEA chains and RBCs. Uncompromised bioactivity of native human hemoglobin in the RBCs on the modified GCE was confirmed by cyclic voltammetry. The modified electrode showed a faster electron transfer rate and better electrocatalytic activity in the reduction of H2O2 than previously reported sensors. A linear relationship is found between the response to H2O2 and its concentration in the range from 0.11 μM to 12.7 mM. The detection limit is 55 nM at an SNR of 3. It is assumed that the improvement of the biosensor results from the porosity and conductivity of the PDEA hydrogel. (author)

  4. Optimized CeO2 content of the carbon nanofiber support of PtRu catalyst for direct methanol fuel cells

    Kunitomo, Hikari; Ishitobi, Hirokazu; Nakagawa, Nobuyoshi

    2015-11-01

    A series of CeO2 embedded carbon nanofibers, CECNFs, with different CeO2 contents was prepared by an electrospinning technique. About 15 wt% PtRu nanoparticles were deposited on the fibers, and the effect of the CeO2 content on the methanol oxidation activity of the catalyst, PtRu/CECNF, was investigated. Cyclic voltammetry (CV), chronoamperometry (CA) and CO stripping electrochemical measurements and physical characterization along with X-ray diffraction (XRD) analysis, energy dispersive X-ray (EDX) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were carried out on the prepared catalysts. The mass activity of the PtRu was significantly increased by the CeO2 addition up to Ce/C = 0.4, and the maximized activity was 2 times higher than that without CeO2. The increased activity was attributed to the strong interaction between the metal and oxide in the embedded nanofiber structure. A DMFC with the PtRu/CECNF exhibited more than 2.5 times high power density with one half the PtRu loading compared to that of the commercial catalyst, PtRu/Ccom.

  5. Bacterial activity and bacterioplankton diversity in the eutrophic River Warnow--direct measurement of bacterial growth efficiency and its effect on carbon utilization.

    Warkentin, Mareike; Freese, Heike M; Schumann, Rhena

    2011-01-01

    The influence of bacterial activity and diversity on bacterial growth efficiency was investigated in a flatland river. Eutrophic River Warnow drains predominantly agricultural land and is heavily loaded with nutrients, dissolved and particulate organic matter (DOM and POM), especially humic substances. Although the water column bacterial community consists of many inactive or damaged cells, bacterioplankton sustained a high bacterial secondary production of 0.2-14.5 μg C L(-1) h(-1) and a high DNA synthesis (thymidine uptake) of 6.1-15.5 μg C L(-1) h(-1). The direct and short-term measurement of bacterial respiration (by optodes) revealed high respiration rates especially in summer leading to directly estimated bacterial growth efficiencies (BGE) of 2-28%. These values are compared to calculations based only on bacterial production, which considerably overestimated BGEs. From all these data, River Warnow can be characterized as a strongly remineralizing system. River Warnow was dominated among others by Cytophaga/Flavobacteria and Actinobacteria which are typical for organic rich waters because of their ability to degrade high molecular weight compounds. However, community composition did not significantly affect BGE. PMID:20676625

  6. The 150-70 Ma APW for stable Adria from direct palaeomagnetic data obtained from biostratigraphically controlled and correlated basin (Adige embayment) and platform (Istria) carbonates

    Complete text of publication follows. During recent years, a systematic paleomagnetic study was carried out on a total of 54 geographically distributed localities from the stable foreland of the Southern Alps (Adige embayement) and from stable Istria, respectively. The exact biostratigraphic ages were assigned to the localities by checking the microphossil for each sampled bed under the microscope and eventually groups of coeval localities from the basin and the platform were defined. These groups are characterized by well-clustered paleomagnetic directions up to the Turonian. With the onset of the Scaglia Rossa deposition paleomagnetic declinations remain remarkably consistent, but the inclinations are significantly shallower in the basin (due to compaction) than in the platform. Comparison between the inclinations for hard-ground and compacted Scaglia from the same section as well as estimation of inclination shallowing from measurements of the anisotropy of the remanence suggested that a factor of 1.18 should be applied to the Scaglia localities. The new APW based on the combination of paleomagnetic directions from the Adige embayement (corrected for inclination shallowing for Turonian and younger Cretaceous) and stable Istria comprises paleomagnetic poles for eight time intervals. Its length is comparable to that of the synthetic APW for Africa for the investigated time interval. However, the direct observations for stable Adria reveal that the best part of the Cretaceous CCW rotation took place during Late Aptian-Early Albian which is the time of emergence for Istria and submarine erosion in the basin. After this quite fast and important displacement, stable Adria rotates slightly but steadily in the CCW sense till the Maastrichtian, without any indication for a short term CW rotation around 80Ma which is evident in the synthetic APW for Africa. Declinations for stable Adria are systematically more westerly than those derived from the African APW. Nevertheless

  7. Directed Polymer -- Directed Percolation Transition

    Perlsman, Ehud; Havlin, Shlomo

    1999-01-01

    We study the relation between the directed polymer and the directed percolation models, for the case of a disordered energy landscape where the energies are taken from bimodal distribution. We find that at the critical concentration of the directed percolation, the directed polymer undergoes a transition from the directed polymer universality class to the directed percolation universality class. We also find that directed percolation clusters affect the characterisrics of the directed polymer...

  8. The direct ionization processes in the collisions of partially stripped carbon and oxygen ions with helium atoms at low-to-intermediate energies

    The values of direct double-to-single ionization ratio R of helium atoms induced by Cq+, Oq++ (q = 1–4) ions at incident energies from 0.2 to 8.5MeV are measured. Based on the existing model (Shao J X, Chen X M and Ding B W 2007 Phys. Rev. A 75 012701) the effective charge of the projectile is introduced to theoretically estimate the value of R for the partially stripped ions impacting on helium atoms. The results calculated from our 'effective charge' model are in good agreement with the experimental data, and the dependence of the effective charge on the ionization energy of the projectile is also discussed qualitatively. (atomic and molecular physics)

  9. The direct ionization processes in the collisions of partially stripped carbon and oxygen ions with helium atoms at low-to-intermediate energies

    Zhou Chun-Lin; Shao Jian-Xiong; Chen Xi-Meng; Sun Guang-Zhi; Zou Xian-Rong

    2008-01-01

    The values of direct double- to-single ionization ratio R of helium atoms induced by Cq+,Oq+ (q=1-4) ions at incident energies from 0.2 to 8.5MeV are measured.Based on the existing model (Shao J X,Chen X M and Ding B W 2007 Phys.Rev.A 75 012701) the effective charge of the projectile is introduced to theoretically estimate the value of R for the partially stripped ions impacting on helium atoms.The results calculated from our "effective charge" model are in good agreement with the experimental data,and the dependence of the effective charge on the ionization energy of the projectile is also discussed qualitatively.

  10. Towards the development of a direct electrochemical biodetector of avidin based on the poly(chloro amino β-styryl terthiophene)-coated glassy carbon electrode

    Mehenni, Hakim

    2012-03-30

    In this study, a simple and direct biodetector was proposed, which was based on biotin immobilized onto a conducting polymer-coated electrode, for the detection of avidin, a highly stable glycoprotein found in egg-whites. Biotin was immobilized onto the electrode by covalent coupling to the primary amine group on the poly 3′-(3-chloro-4-amino-β-styryl)-(2,2′: 5′,2″-terthiophene) (PCAST), and the biotinavidin interaction was monitored by cyclic voltammetry. Incubation of the PCAST/biotin-modified-coated electrode with avidin in a phosphate buffered saline solution caused a significant change to its cyclic voltammogram, which was explained by the binding of avidin by biotin, and resulted in restricted ion transfer to and from the conducting polymer. This change was then utilized to detect avidin at 4 × 10 -6molL -1. © 2012 CSIRO.

  11. Modeling state-level soil carbon emission factors under various scenarios for direct land use change associated with United States biofuel feedstock production

    Current estimates of life cycle greenhouse gas emissions of biofuels produced in the US can be improved by refining soil C emission factors (EF; C emissions per land area per year) for direct land use change associated with different biofuel feedstock scenarios. We developed a modeling framework to estimate these EFs at the state-level by utilizing remote sensing data, national statistics databases, and a surrogate model for CENTURY's soil organic C dynamics submodel (SCSOC). We estimated the forward change in soil C concentration within the 0–30 cm depth and computed the associated EFs for the 2011 to 2040 period for croplands, grasslands or pasture/hay, croplands/conservation reserve, and forests that were suited to produce any of four possible biofuel feedstock systems [corn (Zea Mays L)-corn, corn–corn with stover harvest, switchgrass (Panicum virgatum L), and miscanthus (Miscanthus × giganteus Greef et Deuter)]. Our results predict smaller losses or even modest gains in sequestration for corn based systems, particularly on existing croplands, than previous efforts and support assertions that production of perennial grasses will lead to negative emissions in most situations and that conversion of forest or established grasslands to biofuel production would likely produce net emissions. The proposed framework and use of the SCSOC provide transparency and relative simplicity that permit users to easily modify model inputs to inform biofuel feedstock production targets set forth by policy. -- Highlights: ► We model regionalized feedstock-specific United States soil C emission factors. ► We simulate soil C changes from direct land use change associated with biofuel feedstock production. ► Corn, corn-stover, and perennial grass biofuel feedstocks grown in croplands maintain soil C levels. ► Converting grasslands to bioenergy crops risks soil C loss. ► This modeling framework yields more refined soil C emissions than national-level emissions

  12. On-demand supply of slurry fuels to a porous anode of a direct carbon fuel cell: Attempts to increase fuel-anode contact and realize long-term operation

    Li, Chengguo; Yi, Hakgyu; Lee, Donggeun

    2016-03-01

    In this paper, we propose a novel idea that might allow resolution of the two biggest challenges that hinder practical use of direct carbon fuel cells (DCFC). This work involved 1) the use of three types of porous Ni anode with different pore sizes, 2) size matching between the anode pores and solid fuel particles in a molten-carbonate (MC) slurry, and 3) provision of a continuous supply of fuel-MC slurry through the porous Ni anode. As a result, larger numbers of smaller pores in the anode were preferred for extending the triple phase boundary (TPB), as long as the fuel particles were sufficiently small to have full access to the inner pore spaces of the anode. For example, the maximal power density achieved in the case of optimal size matching, reached 645 mW cm-2, which is 14-times greater than that for the case of poorest size-matching and 64-times larger than that for a non-porous anode, and lasted for more than 20 h. After 20 h of steady operation at a fixed current density (700 mA cm-2), the electric potential slightly decreased due to partial consumption of the fuel. The cell performance readily recovered after restarting the supply of MC-fuel slurry.

  13. M-shell electron capture and direct ionization of gold by 25-MeV carbon and 32-MeV oxygen ions

    M-shell x-ray production cross sections have been measured for thin solid targets of Au for 25 MeV 12C/sup q+/ (q = 4, 5, 6) and for 32 MeV 16O/sup q+/ (q = 5, 7, 8). The microscopic cross sections were determined from measurements made with targets ranging in thickness from 0.5 to 100 μg/cm2. For projectiles with one or two K-shell vacancies, the M-shell x-ray production cross sections are found to be enhanced over those by projectiles without a K-shell vacancy. The sum of direct ionization to the continuum (DI) and electron capture (EC) to the L, M, N ... shells and EC to the K-shell of the projectile have been extracted from the data. The results are compared to the predictions of first Born theories i.e. PWBA for DI and OBK of Nikolaev for EC and the ECPSSR approach that accounts for energy loss, Coulomb deflection and relativistic effects in the perturbed stationary state theory. 25 references, 3 figures, 1 table

  14. Electrostatic interactions for directed assembly of high performance nanostructured energetic materials of Al/Fe2O3/multi-walled carbon nanotube (MWCNT)

    Zhang, Tianfu; Ma, Zhuang; Li, Guoping; Wang, Zhen; Zhao, Benbo; Luo, Yunjun

    2016-05-01

    Electrostatic self-assembly in organic solvent without intensively oxidative or corrosive environments, was adopted to prepare Al/Fe2O3/MWCNT nanostructured energetic materials as an energy generating material. The negatively charged MWCNT was used as a glue-like agent to direct the self-assembly of the well dispersed positively charged Al (fuel) and Fe2O3 (oxide) nanoparticles. This spontaneous assembly method without any surfactant chemistry or other chemical and biological moieties decreased the aggregation of the same nanoparticles largely, moreover, the poor interfacial contact between the Al (fuel) and Fe2O3 (oxide) nanoparticles was improved significantly, which was the key characteristic of high performance nanostructured energetic materials. In addition, the assembly process was confirmed as Diffusion-Limited Aggregation. The assembled Al/Fe2O3/MWCNT nanostructured energetic materials showed excellent performance with heat release of 2400 J/g, peak pressure of 0.42 MPa and pressurization rate of 105.71 MPa/s, superior to that in the control group Al/Fe2O3 nanostructured energetic materials prepared by sonication with heat release of 1326 J/g, peak pressure of 0.19 MPa and pressurization rate of 33.33 MPa/s. Therefore, the approach, which is facile, opens a promising route to the high performance nanostructured energetic materials.

  15. Highly active carbon supported palladium-rhodium PdXRh/C catalysts for methanol electrooxidation in alkaline media and their performance in anion exchange direct methanol fuel cells (AEM-DMFCs)

    Highlights: • Synthesis and physical evaluation of carbon supported, Rh containing Pd electrocatalysts. • Electroactivity towards methanol oxidation strongly enhanced in alkaline media. • Bimetallic catalyst show low CO oxidation and OH adsorption potentials. • CO2 current efficiency higher for bimetallic catalysts than for Pt/C or Pd/C. • Power density of 105 mW cm−2 for platinum-free alkaline direct methanol fuel cell. - Abstract: In this study carbon supported PdXRh electrocatalysts synthesized by wet chemical reduction process were tested for the potential use in anion-exchange membrane direct methanol fuel cells (AEM-DMFC) and compared to Pd/C and commercially available Pt/C. A metal loading of 20wt% on carbon was confirmed by thermogravimetric analysis (TGA) and catalyst compositions of PdRh3/C, PdRh/C and Pd3Rh/C were found via inductively coupled plasma optical emission spectroscopy (ICP-OES). Transmission electron microscopy (TEM) and x-ray diffraction (XRD) studies showed that the average particle and crystallite sizes of the PdXRh/C catalysts are in the range of 3.1 to 4.3 nm. It was also found that these catalysts are not alloyed. Cyclic voltammetry (CV) data reveals a 85–140 mV lower CH3OH oxidation onset potential and higher mass current densities for PdXRh/C catalysts compared with Pd/C. Steady-state measurements via chronoamperometry (CA) showed a good stability against poisoning during methanol oxidation and higher mass activities for PdRh/C and Pd3Rh/C compared to Pt/C. By using differential electrochemical mass spectrometry (DEMS) it was successfully shown that adding Rh to Pd results in an enhanced CO2 current efficiency (CCE) compared to Pd/C or Pt/C. AEM-DMFCs free from platinum were fabricated and single cell tests at 60 °C showed a significant increase of power density at 0.5 V cell potential from 4.8 mW cm−2 for Pd/C to 16.5 mW cm−2 for PdRh/C with the anode and cathode fed with 1 M methanol + 2 M KOH and synthetic air

  16. Carbon Carbon Composites: An Overview .

    G. Rohini Devi; K. Rama Rao

    1993-01-01

    Carbon carbon composites are a new class of engineering materials that are ceramic in nature but exhibit brittle to pseudoplastic behaviour. Carbon-carbon is a unique all-carbon composite with carbon fibre embeded in carbon matrix and is known as an inverse composite. Due to their excellent thermo-structural properties, carbon-carbon composites are used in specialised application like re-entry nose-tips, leading edges, rocket nozzles, and aircraft brake discs apart from several indust...

  17. Accelerating Mineral Carbonation Using Carbonic Anhydrase.

    Power, Ian M; Harrison, Anna L; Dipple, Gregory M

    2016-03-01

    Carbonic anhydrase (CA) enzymes have gained considerable attention for their potential use in carbon dioxide (CO2) capture technologies because they are able to catalyze rapidly the interconversion of aqueous CO2 and bicarbonate. However, there are challenges for widespread implementation including the need to develop mineralization process routes for permanent carbon storage. Mineral carbonation of highly reactive feedstocks may be limited by the supply rate of CO2. This rate limitation can be directly addressed by incorporating enzyme-catalyzed CO2 hydration. This study examined the effects of bovine carbonic anhydrase (BCA) and CO2-rich gas streams on the carbonation rate of brucite [Mg(OH)2], a highly reactive mineral. Alkaline brucite slurries were amended with BCA and supplied with 10% CO2 gas while aqueous chemistry and solids were monitored throughout the experiments (hours to days). In comparison to controls, brucite carbonation using BCA was accelerated by up to 240%. Nesquehonite [MgCO3·3H2O] precipitation limited the accumulation of hydrated CO2 species, apparently preventing BCA from catalyzing the dehydration reaction. Geochemical models reproduce observed reaction progress in all experiments, revealing a linear correlation between CO2 uptake and carbonation rate. Data demonstrates that carbonation in BCA-amended reactors remained limited by CO2 supply, implying further acceleration is possible. PMID:26829491

  18. Analysis of the reaction process in solid oxide direct carbon fuel cell anode%固体氧化物直接碳燃料电池阳极反应过程分析

    刘国阳; 周安宁; 张亚婷; 蔡江涛; 党永强; 邱介山

    2015-01-01

    A direct carbon fuel cell ( DCFC) was assembled with yttria stabilized zirconia ( YSZ) as electrolyte and active carbon ( AC) , graphite ( G) and semi-coke ( SC) were employed as the DCFC fuels. The influences of the carbon fuel pore structure and reactivity, operation temperature, anode atmosphere on the anode reaction were investigated. The results indicated that for three carbonaceous fuels, the performance of DCFC is in the order of AC >SC >G, the same as that for their oxidation reactivity in air or CO2 atmosphere. The reactivity of carbonaceous fuels is determined by their surface oxygenic functional groups and pore structure. Moreover, the results revealed that the DCFC anodic reactions involves the oxidation of C to CO2 , the conversion of CO2 to CO via the reverse Boudouard reaction, and the oxidation of CO to CO2 .%以氧化钇稳定的氧化锆( YSZ)为电解质组装成直接碳燃料电池( DCFC),分别以活性炭( AC)、石墨( G)、神府半焦( SC)作为DCFC燃料,研究了碳燃料的特性、电池操作温度以及阳极反应气氛等对DCFC阳极反应过程的影响。结果表明,三种碳燃料在空气、CO2气氛中氧化反应活性顺序为AC > SC > G,当三种碳材料作为DCFC燃料时,活性炭作为燃料的DCFC性能最好,半焦燃料次之,石墨作为燃料的DCFC性能最差,而且燃料反应活性与其表面含氧官能团、孔隙结构有关;DCFC的阳极反应过程存在碳燃料直接氧化为CO2、CO2与C反应转化为CO,以及CO氧化为CO2等。

  19. Emulsion droplets as a dynamic interface for the direct and large-scale synthesis of ultrathin free-standing mesoporous silica films as well as 2D polymeric and carbon nanomaterials

    Li, Jian; Zhu, Wei; Ji, Jingwei; Wang, Peng; Wang, Chen; Yin, Xianpeng; Wang, Hui; Lan, Yue; Gao, Ning; Li, Guangtao

    2016-01-01

    The efficient synthesis of free-standing mesostructured two-dimensional (2D) nanofilms with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness represents a big challenge. In this work, it was serendipitously found that microemulsion droplets of tetraethylorthosilicate (TEOS) could serve as a novel dynamic interface for continuous growth of nanofilms. Based on this finding, a general, efficient strategy for the direct and large-scale synthesis of free-standing mesoporous silica films (FSMSFs) was developed. Remarkably, with the careful control of the synthesis conditions, the FSMSFs with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness could be efficiently achievable. More importantly, by using polymerizable surfactants the preorganized monomers in the nanochannels of the resultant silica films could be further converted into 2D polymers and carbon nanomaterials as well as metal particle-decorated forms, as exemplified by using pyrrole-terminated surfactants, demonstrating a powerful method to create 2D inorganic, organic or hybrid functional nanomaterials.The efficient synthesis of free-standing mesostructured two-dimensional (2D) nanofilms with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness represents a big challenge. In this work, it was serendipitously found that microemulsion droplets of tetraethylorthosilicate (TEOS) could serve as a novel dynamic interface for continuous growth of nanofilms. Based on this finding, a general, efficient strategy for the direct and large-scale synthesis of free-standing mesoporous silica films (FSMSFs) was developed. Remarkably, with the careful control of the synthesis conditions, the FSMSFs with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness could be efficiently

  20. The carbon footprint of reinforced concrete

    Purnell, P

    2013-01-01

    As legislation forces significant reductions in the operational carbon dioxide emissions of the built environment, increasing attention is focused on the embodied carbon of structural materials. As the most prevalent structural material, the embodied carbon of concrete is of paramount interest. Previous direct or indirect analyses of embodied carbon in concrete have treated it either as an elemental material with a value of single embodied carbon, or calculated embodied carbon for a limited r...

  1. Carbon nanotube junctions and devices

    Postma, H. W. Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconducting behaviour. Due to their small diameter, electronic motion is directed in the length direction of the nanotube, making them ideal systems to study e.g. one-dimensional transport phenomena. First...

  2. New Relationship in Carbon Cycle

    Aleksei Naumov

    2012-01-01

    The problem of carbon dioxide accumulation in the atmosphere is closely related to the biological carbon cycle processes insufficiently studied from the global viewpoint. Based on data obtained from the literature on net primary production (NPP) and soil respiration (SR) of world ecosystems, a quantitative analysis of the relationship between these basic parameters of the production/destruction phase of the carbon cycle is offered in this paper. A direct correspondence (equality in carbon equ...

  3. Directed homology

    Fahrenberg, Uli

    2004-01-01

    We introduce a new notion of directed homology for semicubical sets. We show that it respects directed homotopy and is functorial, and that it appears to enjoy some good algebraic properties. Our work has applications to higher-dimensional automata.......We introduce a new notion of directed homology for semicubical sets. We show that it respects directed homotopy and is functorial, and that it appears to enjoy some good algebraic properties. Our work has applications to higher-dimensional automata....

  4. Direct fuel cell power plants: the final steps to commercialization

    Glenn, Donald R.

    Since the last paper presented at the Second Grove Fuel Cell Symposium, the Energy Research Corporation (ERC) has established two commercial subsidiaries, become a publically-held firm, expanded its facilities and has moved the direct fuel cell (DFC) technology and systems significantly closer to commercial readiness. The subsidiaries, the Fuel Cell Engineering Corporation (FCE) and Fuel Cell Manufacturing Corporation (FCMC) are perfecting their respective roles in the company's strategy to commercialize its DFC technology. FCE is the prime contractor for the Santa Clara Demonstration and is establishing the needed marketing, sales, engineering, and servicing functions. FCMC in addition to producing the stacks and stack modules for the Santa Clara demonstration plant is now upgrading its production capability and product yields, and retooling for the final stack scale-up for the commercial unit. ERC has built and operated the tallest and largest capacities-to-date carbonate fuel cell stacks as well as numerous short stacks. While most of these units were tested at ERC's Danbury, Connecticut (USA) R&D Center, others have been evaluated at other domestic and overseas facilities using a variety of fuels. ERC has supplied stacks to Elkraft and MTU for tests with natural gas, and RWE in Germany where coal-derived gas were used. Additional stack test activities have been performed by MELCO and Sanyo in Japan. Information from some of these activities is protected by ERC's license arrangements with these firms. However, permission for limited data releases will be requested to provide the Grove Conference with up-to-date results. Arguably the most dramatic demonstration of carbonate fuel cells in the utility-scale, 2 MW power plant demonstration unit, located in the City of Santa Clara, California. Construction of the unit's balance-of-plant (BOP) has been completed and the installed equipment has been operationally checked. Two of the four DFC stack sub-modules, each

  5. Direct hydrocarbon fuel cells

    Barnett, Scott A.; Lai, Tammy; Liu, Jiang

    2010-05-04

    The direct electrochemical oxidation of hydrocarbons in solid oxide fuel cells, to generate greater power densities at lower temperatures without carbon deposition. The performance obtained is comparable to that of fuel cells used for hydrogen, and is achieved by using novel anode composites at low operating temperatures. Such solid oxide fuel cells, regardless of fuel source or operation, can be configured advantageously using the structural geometries of this invention.

  6. Emulsion droplets as a dynamic interface for the direct and large-scale synthesis of ultrathin free-standing mesoporous silica films as well as 2D polymeric and carbon nanomaterials.

    Li, Jian; Zhu, Wei; Ji, Jingwei; Wang, Peng; Wang, Chen; Yin, Xianpeng; Wang, Hui; Lan, Yue; Gao, Ning; Li, Guangtao

    2016-01-28

    The efficient synthesis of free-standing mesostructured two-dimensional (2D) nanofilms with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness represents a big challenge. In this work, it was serendipitously found that microemulsion droplets of tetraethylorthosilicate (TEOS) could serve as a novel dynamic interface for continuous growth of nanofilms. Based on this finding, a general, efficient strategy for the direct and large-scale synthesis of free-standing mesoporous silica films (FSMSFs) was developed. Remarkably, with the careful control of the synthesis conditions, the FSMSFs with high-yield as well as good control of composite, mesophase structure, orientation of the pore channel and thickness could be efficiently achievable. More importantly, by using polymerizable surfactants the preorganized monomers in the nanochannels of the resultant silica films could be further converted into 2D polymers and carbon nanomaterials as well as metal particle-decorated forms, as exemplified by using pyrrole-terminated surfactants, demonstrating a powerful method to create 2D inorganic, organic or hybrid functional nanomaterials. PMID:26785674

  7. A new alkali-resistant Ni/Al2O3-MSU-1 core-shell catalyst for methane steam reforming in a direct internal reforming molten carbonate fuel cell

    Zhang, Jian; Zhang, Xiongfu; Liu, Weifeng; Liu, Haiou; Qiu, Jieshan; Yeung, King Lun

    2014-01-01

    An alkali-resistant catalyst for direct internal reforming molten carbonate fuel cell (DIR-MCFC) is prepared by growing a thin shell of mesoporous MSU-1 membrane on Ni/Al2O3 catalyst beads. The MSU-1 shell is obtained by first depositing a monolayer of colloidal silicalite-1 (Sil-1) on the catalyst bead as linkers and then using NaF stored in the beads to catalyze the growth of the MSU-1 layer. The resulting core-shell catalysts display excellent alkali-resistance and deliver stable methane conversion and hydrogen yield in an out-of-cell test simulating the operating conditions of an operating DIR-MCFC. Higher conversion and yield (i.e., up to over 70%) are obtained from the new core-shell catalyst with MSU-1 shell compared to the catalyst with microporous Sil-1 shell. A mathematical model of the reaction and poisoning of the core-shell catalyst is used to predict the optimum shell thickness for its reliable use in a DIR-MCFC.

  8. 城市居住区内家庭直接能耗碳排放差异研究%Research on the Difference in Carbon Emissions Due to Direct Household Energy Consumption in the Same Urban Residential Community

    张艳; 秦耀辰

    2012-01-01

    家庭能源消费对环境的影响已经成为可持续发展领域热点研究课题之一.基于微观视角,采用多段抽取的方法从南阳市一商业居住区内选取128户家庭进行住户的调研,针对具有不同的家庭规模、家庭收入、房屋所有权、家庭成员节能意识及能源知识掌握程度的家庭,分别分析了其直接能耗CO2排放量和结构上的差异.用多元逐步回归的方法,得到了家庭成员节能意识强烈度、家庭人口、家庭成年人平均文化程度、能源知识掌握程度等是造成同一居住区内家庭CO2排放差异的显著性因子,家庭成员节能意识的强烈程度、能源知识的掌握程度与家庭直接能耗CO2排放量呈负相关,因此,加强对居民的能源知识的普及和节能意识的强化可以降低家庭直接能耗的CO2排放量.%The impact on the environment due to household energy consumption has become one of the hotspot issues in the field of sustainable development. In order to study the difference in carbon emissions due to direct household energy consumption in the same urban residential community, 128 households are selected from a commercial residential community by multy selection. The difference in households CO2 emissions due to direct energy consumption are analyzed according to the different family numbers, different income, house droit, energy saving consciousness, energy knowledge. The analysis shows that energy saving consciousness, family numbers, family income, energy knowledge are the most important sources of household CO2 emissions due to direct energy consumption.

  9. Direct Democracy

    Beramendi, Virginia; Ellis, Andrew; Kaufman, Bruno;

    While many books on direct democracy have a regional or national approach, or simply focus on one of the many mechanisms associated with direct democracy, this Handbook delves into a global comparison of direct democracy mechanisms, including referendums, citizens' initiatives, agenda initiatives...... included as a chapter in the Handbook are possible measures for best practices of implementation, designed for those who wish to tailor direct democracy instruments to their specific needs. In order to further complement the best practices, a variety of global case studies detail the practical uses of...... direct democracy mechanisms in specific contexts. These country case studies allow for in depth discussion of particular issues, including signature collection and voter participation, campaign financing, media coverage, national variations in the usage of direct democracy procedures and national lessons...

  10. Direct Electrochemistry of Glucose Oxidase on A Nano Complex Modified Glassy Carbon Electrode%葡萄糖氧化酶在修饰玻碳电极上的直接电化学

    耿方勇; 李迪; 张钰帅; 杨晓璐; 肖宝林; 洪军

    2016-01-01

    Direct electrochemistry of glucose oxidase was realized when it was immobilized on a nano-complex modified glassy carbon electrode, and the nano-complex was composed of graphene and multi-walled carbon nanotubes. The outermost layer covered with chitosan. Using cyclic voltammetry ( CV ) to measure electrochemical and electro-catalyzed reaction of glucose oxidase that modified electrode, the electron transfer rate constant (ks) was evaluated to be 0. 87 s-1, and electroactive surface density was 1. 54í10-10 mol/cm-2. The apparent Michaelis-Menten constant (Kappm ) was 1. 32í103 μmol/L, linear detection range was 40 ~1000 μmol/L, and the modified electrode had better stability, and modified electrode had good anti-interference ability when detected the substrate. Therefore, the modified electrode can be used to detect glucose, as the third generation biosensors.%将葡萄糖氧化酶( Glucose oxidase, GOD)固定在由多壁碳纳米管( MWCNTS)和石墨烯( Graphene)构成的纳米复合材料修饰的玻碳电极上,最外层用壳聚糖( Chitosan)进行覆盖,利用循环伏安法( Cyclic Voltammetry, CV)来测量葡萄糖氧化酶在修饰电极上的电化学和电催化反应,测得电子传递速率常数ks 为0.87 s-1,电活性物质表面密度Г为1.54×10-10 mol/cm-2,动力学表观米氏常数Km 为1.32×103μmol/L,线性检测范围为:40~1000μmol/L,修饰电极有较好的稳定性,而且修饰电极在检测底物时有较好的抗干扰能力,因此,该体系修饰的电极有希望构建第三代葡萄糖生物传感器。

  11. Analysis and monitoring of carbon in sodium

    Chemical analyses used by SCK/CEN at Mol Belgium, in the carbon mass transfer studies include on-line activity measurements, and off-line carbon determinations on sodium samples and on alloys equilibrated with the carbon activity in the loop sodium. For carbon activity measurements efforts were directed to the development of EMF and diffusion type carbon meters. The Monitor tab technique was used for calibration. Chemical off-line analyses were developed for identification and measurement of total carbon and for carbon chemical states in the ppb range. Analysed chemical states are carbides, Carbonates, Carbonyl and Cyanide. (author)

  12. Climate control of terrestrial carbon exchange across biomes and continents

    Yi, Chuixiang; Ricciuto, Daniel; Li, Runze;

    2010-01-01

    Understanding the relationships between climate and carbon exchange by terrestrial ecosystems is critical to predict future levels of atmospheric carbon dioxide because of the potential accelerating effects of positive climate–carbon cycle feedbacks. However, directly observed relationships betwe...

  13. Directing 101.

    Pintoff, Ernest

    Providing an introduction to anyone considering directing as a field of study or career, this book takes a broad look at the process of directing and encourages students and professionals alike to look outside of the movie industry for inspiration. Chapters in the book discuss selecting and acquiring material; budgeting and financing; casting and…

  14. Investigation of carbon monoxide tolerance of platinum nanoparticles in the presence of optimum ratio of doped polyaniline with para toluene sulfonic acid and their utilization in a real passive direct methanol fuel cell

    Highlights: ► Onset potential of methanol oxidation on Pt/C-PANI-PTSA electrocatalysts is close to Pt–Ru catalyst. ► The methanol crossover in the presence of Pt/C-20%PANI-PTSA reduced by 59% compared with Pt/C (Electrochem). ► The energy efficiency of Pt/C-20%PANI-PTSA as anode is 2.18 times more than Pt/C. -- Abstract: Polyaniline fiber (PANI) was synthesized by chemical interfacial method and doped with para toluene sulfonic acid (PTSA) through a sequential doping–dedoping–redoping process resulting in PANI-PTSA. The doped material was utilized to fabricate Vulcan-polyaniline composite of C-PANI-PTSA. Next, through reduction, Pt particles were deposited on to this composite to produce a Pt/C-PANI-PTSA electrocatalyst. To investigate the PANI-PTSA interaction with the carbon support as well as, to consider its effect upon the catalytic activity of Pt/C-PANI-PTSA, electrocatalysts with different ratios of 10, 15, 20, 25 and 30 wt% were synthesized and their activity was compared with the Pt/C (Electrochem). Results revealed that, the peak current density in methanol electro-oxidation, electrochemical surface area, methanol diffusion coefficient, charge transfer resistance as well as; the stability of the Pt/C-20%PANI-PTSA electrocatalyst were all markedly improved for the synthesized material. Moreover, the Pt/C-20%PANI-PTSA was demonstrated to be more CO tolerant according to the CO stripping voltammetry test. Also powder XRD and TEM techniques were utilized to investigate the crystallite size and the surface morphologies of the catalysts. Finally, the performance of Pt/C-20%PANI-PTSA was compared with Pt/C (Electrochem) in a passive direct methanol fuel cell and the effect of PANI-PTSA on methanol crossover and fuel utilization was analyzed. Ultimately, the Pt/C-20%PANI-PTSA modified catalyst was shown to be more suitable for applying in the direct methanol fuel cells (DMFC) compared with the commercial Pt/C material

  15. Renewable energy and the role of molten salts and carbon

    Fray D.

    2013-01-01

    Full Text Available Molten carbonate fuel cells have been under development for a number of years and reliable units are successfully working at 250kW scale and demonstration units have produced up to 2 MW. Although these cells cannot be considered as renewable as the fuel, hydrogen or carbon monoxide is consumed and not regenerated, the excellent reliability of such a cell can act as a stimulus to innovative development of similar cells with different outcomes. Molten salt electrolytes based upon LiCl - Li2O can be used to convert carbon dioxide, either drawn from the output of a conventional thermal power station or from the atmosphere, to carbon monoxide or carbon. Recently, dimensionally stable anodes have been developed for molten salt electrolytes, based upon alkali or alkaline ruthenates which are highly electronically conducting and these may allow the concept of high temperature batteries to be developed in which an alkali or alkaline earth element reacts with air to form oxides when the battery is discharging and the oxide decomposes when the battery is being recharged. Batteries using these concepts may be based upon the Hall-Heroult cell, which is used worldwide for the production of aluminium on an industrial scale, and could be used for load levelling. Lithium ion batteries are, at present, the preferred energy source for cars in 2050 as there are sufficient lithium reserves to satisfy the world’s energy needs for this particular application. Graphite is used in lithium ion batteries as the anode but the capacity is relatively low. Silicon and tin have much higher capacities and the use of these materials, encapsulated in carbon nanotubes and nanoparticles will be described. This paper will review these interesting developments and demonstrate that a combination of carbon and molten salts can offer novel ways of storing energy and converting carbon dioxide into useful products.

  16. Water as a Direct Hydrogen Donor in Supercritical Carbon Di-oxide: A Novel and Efficient Zn-H2O-CO2 System for Chemo selective Reduction of Nitrobenzenes to Anilines

    JIANG Huan-Feng; DONG Yao-Sen

    2008-01-01

    An eco-friendly and cheap Zn-H2O-CO2 system was presented for chemoselective reduction of nitrobenzenes to anilines with high yields (80%-97% isolated yields) in supercritical carbon dioxide. This process brings together the very important green chemistry technologies--the use of carbon dioxide as a solvent and the use of water as a hydrogen donor.

  17. Carbon Dioxide Embolism during Laparoscopic Surgery

    Park, Eun Young; Kwon, Ja-Young; Kim, Ki Jun

    2012-01-01

    Clinically significant carbon dioxide embolism is a rare but potentially fatal complication of anesthesia administered during laparoscopic surgery. Its most common cause is inadvertent injection of carbon dioxide into a large vein, artery or solid organ. This error usually occurs during or shortly after insufflation of carbon dioxide into the body cavity, but may result from direct intravascular insufflation of carbon dioxide during surgery. Clinical presentation of carbon dioxide embolism ra...

  18. Directing Creativity

    Darsø, Lotte; Ibbotson, Piers

    2008-01-01

    In this article we argue that leaders facing complex challenges can learn from the arts, specifically that leaders can learn by examining how theatre directors direct creativity through creative constraints. We suggest that perceiving creativity as a boundary phenomenon is helpful for directing it....... Like leaders, who are caught in paradoxical situations where they have to manage production and logistics simultaneously with making space for creativity and innovation, theatre directors need to find the delicate balance between on one hand renewal of perceptions, acting and interaction and on the...... other hand getting ready for the opening night. We conclude that the art of directing creativity is linked to developing competencies of conscious presence, attention and vigilance, whereas the craft of directing creativity concerns communication, framing and choice....

  19. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide;

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon......-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance of...

  20. Carbon Dioxide, Energy Taxes and Household Income

    Cathal O'Donoghue

    1997-01-01

    This paper examines the impact of a carbon tax on the income distribution in Ireland using the 1987 Household Budget Survey. Previous studies have focused on the direct impact of the carbon tax on expenditures on domestic fuels. This study however, drawing on previous work expands the analysis to cover the indirect impact of carbon taxes on other household purchases> A direct and indirect tax would have a less regressive effect on the income distribution than a simple direct tax on household ...

  1. High performance ultracapacitors with carbon nanomaterials and ionic liquids

    Lu, Wen; Henry, Kent Douglas

    2012-10-09

    The present invention is directed to the use of carbon nanotubes and/or electrolyte structures in various electrochemical devices, such as ultracapacitors having an ionic liquid electrolyte. The carbon nanotubes are preferably aligned carbon nanotubes. Compared to randomly entangled carbon nanotubes, aligned carbon nanotubes can have better defined pore structures and higher specific surface areas.

  2. Direct Taxation - Directions of Harmonization

    Narcis Eduard MITU

    2008-01-01

    Most often, harmonization in the fiscal field concerned indirect taxation, and was aimed at assuring that national tax system do not interfere with the freedom of movement of goods, services, persons and capitals. There is no need to harmonize most part of direct taxation rules, as they are strictly enforceable the EU member states and they are thus an attribute of these states sovereignty. In the field of direct taxation, the community acquis mainly concerns the profit (company) tax and the ...

  3. Directed Replacement

    Karttunen, L

    1996-01-01

    This paper introduces to the finite-state calculus a family of directed replace operators. In contrast to the simple replace expression, UPPER -> LOWER, defined in Karttunen (ACL-95), the new directed version, UPPER @-> LOWER, yields an unambiguous transducer if the lower language consists of a single string. It transduces the input string from left to right, making only the longest possible replacement at each point. A new type of replacement expression, UPPER @-> PREFIX ... SUFFIX, yields a transducer that inserts text around strings that are instances of UPPER. The symbol ... denotes the matching part of the input which itself remains unchanged. PREFIX and SUFFIX are regular expressions describing the insertions. Expressions of the type UPPER @-> PREFIX ... SUFFIX may be used to compose a deterministic parser for a ``local grammar'' in the sense of Gross (1989). Other useful applications of directed replacement include tokenization and filtering of text streams.

  4. Selective functionalization of carbon nanotubes

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  5. Grid Compatibility of Variable Speed Wind Turbines with Directly Coupled Synchronous Generator and Hydro-Dynamically Controlled Gearbox

    Mueller, H.; Poeller, M. [DIgSILENT GmbH, 72810 Gomaringen (Germany); Basteck, A.; Tilscher, M.; Pfister, J. [Voith Turbo GmbH and Co. KG, 74564 Crailsheim (Germany)

    2006-07-01

    This paper analyzes grid integration aspects of a new type of variable-speed wind turbine, the directly coupled synchronous generator with hydro-dynamically controlled gearbox. In contrast to existing wind generators using synchronous generators, the generator of this concept is directly connected to the AC grid, without the application of any power electronics converter. Variable speed operation of the turbine is mechanically achieved by a gear box with continuously controllable variable gear box ratio. For this purpose, a detailed dynamic model of a 2 MW wind turbine with a Voith WinDrive has been implemented using the modelling environment of the simulation software DIgSILENT PowerFactory. For investigating grid compatibility aspects of this new wind generator concept, a model of a 50 MW wind farm, with typical layout, based on 25 wind turbines of the 2 MW-class has been analyzed. This paper focuses on the compatibility of the new concept with existing connection standards, such as the E.ON grid code. Of special interest are typical stability phenomena of synchronous generators, such as transient and oscillatory stability as well as power quality issues like voltage flicker. The results of stability studies are presented and possible advantages of the new concept with special focus on offshore applications are discussed.

  6. Carbon dioxide conversion over carbon-based nanocatalysts.

    Khavarian, Mehrnoush; Chai, Siang-Piao; Mohamed, Abdul Rahman

    2013-07-01

    The utilization of carbon dioxide for the production of valuable chemicals via catalysts is one of the efficient ways to mitigate the greenhouse gases in the atmosphere. It is known that the carbon dioxide conversion and product yields are still low even if the reaction is operated at high pressure and temperature. The carbon dioxide utilization and conversion provides many challenges in exploring new concepts and opportunities for development of unique catalysts for the purpose of activating the carbon dioxide molecules. In this paper, the role of carbon-based nanocatalysts in the hydrogenation of carbon dioxide and direct synthesis of dimethyl carbonate from carbon dioxide and methanol are reviewed. The current catalytic results obtained with different carbon-based nanocatalysts systems are presented and how these materials contribute to the carbon dioxide conversion is explained. In addition, different strategies and preparation methods of nanometallic catalysts on various carbon supports are described to optimize the dispersion of metal nanoparticles and catalytic activity. PMID:23901504

  7. Carbon based prosthetic devices

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

    1998-12-31

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

  8. Compilation of carbon-14 data

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

  9. Irradiation-induced structure and property changes in tokamak plasma-facing, carbon-carbon composites

    Carbon-carbon composites are an attractive choice for fusion reactor plasma-facing components because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation plasma fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER), will require advanced carbon-carbon composite materials possessing high thermal conductivity to manage the anticipated severe heat loads. Moreover, ignition machines such as ITER will produce large neutron fluxes. Consequently, the influence of neutron damage on the structure and properties of carbon-carbon composite materials must be evaluated. Data from two irradiation experiments are reported and discussed here. Carbon-carbon composite materials were irradiated in target capsules in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). A peak damage dose of 4.7 displacements per atom (dpa) at 600 degree C was attained. The carbon materials irradiated included uni-directional, two-directional, and three-directional carbon-carbon composites. Dimensional changes are reported for the composite materials and are related to single crystal dimensional changes through fiber and composite structural models. Moreover, the irradiation-induced dimensional changes are reported and discussed in terms of their architecture, fiber type, and graphitization temperature. The effect of neutron irradiation on thermal conductivity of two three-directional, carbon-carbon composites is reported and the recovery of thermal conductivity due to thermal annealing is discussed

  10. Direct cervicoplasty.

    Jordan, J Randall; Yellin, Seth

    2014-08-01

    Rejuvenation of the aging neck is one of the common reasons for the patients presented to facial plastic surgeons. In the author's opinion, most of these patients will be best served by a full rhytidectomy approach with periauricular incisions, skin flap undermining, and platysmaplasty. There is a subset of patients, however, who presented with complaints limited to the so-called Turkey Gobbler deformity, and who do not wish to undergo a full rhytidectomy approach. These patients may be well served by a lesser procedure such as a direct cervicoplasty or submentoplasty. The advantages of this approach include shorter operative time, faster recovery, and lower complication rates. The primary disadvantage of these more limited approaches is that there is an anterior cervical scar that may be visible under some conditions. This article will review the multiple options for skin incisions as well as details of the technique that the authors have found may lead to a successful rejuvenation of the submental region. PMID:25076453

  11. Direct power control of DFIG based on discrete space vector modulation

    Verij Kazemi, Mohammad; Sadeghi Yazdankhah, Ahmad; Madadi Kojabadi, Hossein [Electrical Engineering Department, Sahand University of Technology, Tabriz (Iran)

    2010-05-15

    This paper presents a new direct power control (DPC) strategy for a double fed induction generator (DFIG) based wind energy generation system. Switching vectors for rotor side converter were selected from the optimal switching table using the estimated stator flux position and the errors of the active and reactive power. A few number of voltage vectors may cause undesired power and stator current ripple. In this paper the increased number of voltage vectors with application of the Discrete Space Vector Modulation (DSVM) will be presented. Then a new switching table in supersynchronous and subsynchronous frames will be proposed. Simulation results of a 2 MW DFIG system demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, machine parameters, and wind speed. (author)

  12. Direct observation and analysis of york-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

    Shunsuke Asahina; Mitsuo Suga; Hideyuki Takahashi; Hu Young Jeong; Carolina Galeano; Ferdi Schüth; Osamu Terasaki

    2014-01-01

    Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently ...

  13. New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E-3-(2-aminoarylacrylates or (E-3-(2-aminoarylacrylonitriles

    Qiuping Ding

    2013-03-01

    Full Text Available A new simple and efficient method to construct ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives has been developed from carbon disulfide and (E-3-(2-aminoarylacrylates or (E-3-(2-aminoarylacrylonitriles under mild conditions, without the need for a metal catalyst. The newly developed method tolerates a wide range of substrates in moderate to excellent yields. Moreover, this method is advantageous over previous ones for the easy synthesis of reactants.

  14. Direct fabrication of organic carbon coated VO{sub 2}(B) (VO{sub 2}(B)-C) core-shell structured nanobelts by one step hydrothermal route and its formation mechanism

    Zhang Yifu; Zhang Juecheng; Zhong Yalan [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Yu Lei [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Engineering Research Center of Organosilicon Compound and Material, Ministry of Education of China, Wuhan 430072 (China); Deng Yuan, E-mail: dengy@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Huang Chi, E-mail: chihuang@whu.edu.cn [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Engineering Research Center of Organosilicon Compound and Material, Ministry of Education of China, Wuhan 430072 (China); Liu Xinghai [School of Printing and Packaging, Wuhan University, Wuhan 430079 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer VO{sub 2}(B)-C core-shell nanobelts were synthesized by a one-step hydrothermal route. Black-Right-Pointing-Pointer The effect of glucose and reaction time was briefly discussed. Black-Right-Pointing-Pointer Glucose played a dual role, namely as a reductant and as a carbon precursor. Black-Right-Pointing-Pointer The possible formation mechanism of VO{sub 2}(B)-C was proposed. - Abstract: Organic carbon coated vanadium dioxide (VO{sub 2}(B)-C) core-shell structured nanobelts were successfully synthesized using V{sub 2}O{sub 5} and glucose solution as the starting materials by a facile one-step hydrothermal route. The as-obtained core-shell materials were characterized by scanning electron microscope, transmission electron microscopy, X-ray powder diffraction, energy-dispersive X-ray spectrometer, elemental analysis, Fourier transform infrared spectroscopy and Raman measurements. Some parameters, such as, the concentration of glucose and the reaction time, were briefly discussed to disclose the formation process of VO{sub 2}(B)-C core-shell structured nanobelts. Glucose played a dual role in the hydrothermal process, namely as a reductant to reduce V{sub 2}O{sub 5} to VO{sub 2}(B), and as a carbon precursor for the organic carbon shell. The proper quantity of glucose (i.g.: 0.27 g) was beneficial for the fabrication of VO{sub 2}(B)-C. Furthermore, the possible formation mechanism of VO{sub 2}(B)-C core-shell structured nanobelts was proposed.

  15. Porous carbons

    Satish M Manocha

    2003-02-01

    Carbon in dense as well as porous solid form is used in a variety of applications. Activated porous carbons are made through pyrolysis and activation of carbonaceous natural as well as synthetic precursors. Pyrolysed woods replicate the structure of original wood but as such possess very low surface areas and poor adsorption capacities. On activation, these exhibit increased adsorption volumes of 0.5–0.8 cm3 /gm and surface areas of 700–1800 m2 /gm depending on activation conditions, whether physical or chemical. Former carbons possess mixed pore size distribution while chemically activated carbons predominantly possess micropores. Thus, these carbons can be used for adsorption of wide distributions of molecules from gas to liquid. The molecular adsorption within the pores is due to single layer or multilayer molecule deposition at the pore walls and hence results in different types of adsorption isotherm. On the other hand, activated carbon fibres with controlled microporous structure and surface area in the range of 2500 m2 /gm can be developed by controlled pyrolysis and physical activation of amorphous carbon fibres. Active carbon fibres with unmatchable pore structure and surface characteristics are present and futuristic porous materials for a number of applications from pollution control to energy storage.

  16. Mycorrhizal mediation of soil organic carbon decomposition under elevated atmospheric carbon dioxide

    Significant effort in global change research has recently been directed towards assessing the potential of soil as a carbon sink under future atmospheric carbon dioxide scenarios. Attention has focused on the impact of elevated carbon dioxide on plant interactions with mycorrhizae, a symbiotic soil...

  17. High performance carbon-carbon composites

    Lalit M Manocha

    2003-02-01

    Carbon-carbon composites rank first among ceramic composite materials with a spectrum of properties and applications in various sectors. These composites are made of fibres in various directions and carbonaceous polymers and hydrocarbons as matrix precursors. Their density and properties depend on the type and volume fraction of reinforcement, matrix precursor used and end heat treatment temperature. Composites made with thermosetting resins as matrix precursors possess low densities (1.55–1.75 g/cm3) and well-distributed microporosity whereas those made with pitch as the matrix precursor, after densification exhibit densities of 1.8–2.0 g/cm3 with some mesopores, and those made by the CVD technique with hydrocarbon gases, possess intermediate densities and matrices with close porosities. The former (resin-based) composites exhibit high flexural strength, low toughness and low thermal conductivity, whereas the latter (pitch- and CVD-based) can be made with very high thermal conductivity (400–700 W/MK) in the fibre direction. Carbon-carbon composites are used in a variety of sectors requiring high mechanical properties at elevated temperatures, good frictional properties for brake pads in high speed vehicles or high thermal conductivity for thermal management applications. However, for extended life applications, these composites need to be protected against oxidation either through matrix modification with Si, Zr, Hf etc. or by multilayer oxidation protection coatings consisting of SiC, silica, zircon etc.

  18. Carbon films produced from ionic liquid carbon precursors

    Dai, Sheng; Luo, Huimin; Lee, Je Seung

    2013-11-05

    The invention is directed to a method for producing a film of porous carbon, the method comprising carbonizing a film of an ionic liquid, wherein the ionic liquid has the general formula (X.sup.+a).sub.x(Y.sup.-b).sub.y, wherein the variables a and b are, independently, non-zero integers, and the subscript variables x and y are, independently, non-zero integers, such that ax=by, and at least one of X.sup.+ and Y.sup.- possesses at least one carbon-nitrogen unsaturated bond. The invention is also directed to a composition comprising a porous carbon film possessing a nitrogen content of at least 10 atom %.

  19. Neutron scattering investigation of carbon/carbon composites

    Full text: Carbon/Carbon (C/C) composites, built up from bi-directionally woven fabrics from PAN based carbon fibers, pre-impregnated with phenolic resin followed by pressure curing and carbonization at 1000oC and a final heat treatment at either 1800oC or 2400oC, were investigated by means of small-angle as well as wideangle elastic neutron scattering. Sample orientations arranging the carbon fibers parallel and perpendicular to the incoming beam were examined. Structural features of the composites, i.e. of the fibers as well as the inherently existing pores, are presented and the influence of the heat treatment on the structural properties is discussed. (author)

  20. The effects on direct and indirect energy demand, carbon emissions and investment costs of adding supplementary wall insulation for Norwegian single-family houses built between 1971 and 1980

    Lie, Marianne

    2015-01-01

    In this report, I analyze the energy savings and carbon reduction potential of Norwegian single-family houses constructed between 1971 and 1980 (SFH03) when adding supplementary insulation to the outer walls. The report is split into two parts, where the first part consists of a material analysis and an energy audit for different façade refurbishments of a SFH03 building. The second part covers a scenario analysis of the different insulation solutions when modeling the SFH03 building stock...