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Sample records for carbon nanotube-based permeable

  1. Carbon Nanotube-Based Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Bakajin, O; Noy, A; Huser, T; Eaglesham, D

    2004-04-06

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Assuming Knudsen diffusion through this nanotube membrane, a maximum helium transport rate (for a pressure drop of 1 atm) of 0.25 cc/sec is predicted. Helium flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate greater than 1x10{sup -6} cc/sec. For viscous, laminar flow conditions, water is estimated to flow across the nanotube membrane (under a 1 atm pressure drop) at up to 2.8x10{sup -5} cc/sec (1.7 {micro}L/min).

  2. Carbon Nanotube-Based Permeable Membranes: A Platform for Studying Nanofluidics

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Park, H G; Noy, A; Huser, T; Eaglesham, D; Bakajin, O

    2004-05-25

    A membrane of multiwalled carbon nanotubes embedded in a silicon nitride matrix was fabricated for use in studying fluid mechanics on the nanometer scale. Characterization by fluorescent tracer diffusion and scanning electron microscopy suggests that the membrane is void-free near the silicon substrate on which it rests, implying that the hollow core of the nanotube is the only conduction path for molecular transport. Nitrogen flow measurements of a nanoporous silicon nitride membrane, fabricated by sacrificial removal of carbon, give a flow rate of 0.086 cc/sec. Calculations of water flow across a nanotube membrane give a rate of 2.1x10{sup -6} cc/sec (0.12 {micro}L/min).

  3. Carbon Nanotube Based Molecular Electronics

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash; Menon, Madhu

    1998-01-01

    Carbon nanotubes and the nanotube heterojunctions have recently emerged as excellent candidates for nanoscale molecular electronic device components. Experimental measurements on the conductivity, rectifying behavior and conductivity-chirality correlation have also been made. While quasi-one dimensional simple heterojunctions between nanotubes with different electronic behavior can be generated by introduction of a pair of heptagon-pentagon defects in an otherwise all hexagon graphene sheet. Other complex 3- and 4-point junctions may require other mechanisms. Structural stability as well as local electronic density of states of various nanotube junctions are investigated using a generalized tight-binding molecular dynamics (GDBMD) scheme that incorporates non-orthogonality of the orbitals. The junctions investigated include straight and small angle heterojunctions of various chiralities and diameters; as well as more complex 'T' and 'Y' junctions which do not always obey the usual pentagon-heptagon pair rule. The study of local density of states (LDOS) reveal many interesting features, most prominent among them being the defect-induced states in the gap. The proposed three and four pointjunctions are one of the smallest possible tunnel junctions made entirely of carbon atoms. Furthermore the electronic behavior of the nanotube based device components can be taylored by doping with group III-V elements such as B and N, and BN nanotubes as a wide band gap semiconductor has also been realized in experiments. Structural properties of heteroatomic nanotubes comprising C, B and N will be discussed.

  4. Carbon Nanotube-Based Synthetic Gecko Tapes

    Science.gov (United States)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  5. Carbon Nanotubes Based Quantum Devices

    Science.gov (United States)

    Lu, Jian-Ping

    1999-01-01

    This document represents the final report for the NASA cooperative agreement which studied the application of carbon nanotubes. The accomplishments are reviewed: (1) Wrote a review article on carbon nanotubes and its potentials for applications in nanoscale quantum devices. (2) Extensive studies on the effects of structure deformation on nanotube electronic structure and energy band gaps. (3) Calculated the vibrational spectrum of nanotube rope and the effect of pressure. and (4) Investigate the properties of Li intercalated nanotube ropes and explore their potential for energy storage materials and battery applications. These studies have lead to four publications and seven abstracts in international conferences.

  6. Carbon nanotube based transparent conductive thin films.

    Science.gov (United States)

    Yu, X; Rajamani, R; Stelson, K A; Cui, T

    2006-07-01

    Carbon nanotube (CNT) based optically transparent and electrically conductive thin films are fabricated on plastic substrates in this study. Single-walled carbon nanotubes (SWNTs) are chemically treated with a mixture of concentrated sulfuric acid and nitric acid before being dispersed in aqueous surfactant-contained solutions. SWNT thin films are prepared from the stable SWNT solutions using wet coating techniques. The 100 nm thick SWNT thin film exhibits a surface resistivity of 6 kohms/square nanometer with an average transmittance of 88% on the visible light range, which is three times better than the films prepared from the high purity as-received SWNTs.

  7. Carbon nanotube based hybrid nanocarbon foam

    Science.gov (United States)

    Shahrizan Jamal, M.; Zhang, Mei

    2017-03-01

    Carbon nanotube (CNT) based nanocarbon foams (NFs) and the hybrid nanocarbon foams (HNFs) are fabricated in this work. The NFs are formed by using poly(methyl methacrylate) microspheres as a template to create micro-scaled pores. The cell walls are made of CNT networks with nano-scaled pores. The interconnections among CNTs are secured using graphene and nanographite generated via carbonization of polyacrylonitrile. The resulting NFs are ultra-lightweight, highly elastic, electrically and thermally conductive, and robust in structure. The HNFs are made by infiltrating thermoplastic polymer into the NFs in a controllable procedure. Compared to NFs, the HNFs have much higher strength, same electrical conductivity, and limited increase in density. The compressive strength of the HNF increased more than 50 times while the density was changed less than 10 times due to the polymer infiltration. It is found that the deformed HNFs can recover in both structure and property when they are heated over the glass transition temperature of the infiltrated polymer. Such remarkable healing capability could broaden the applications of the HNFs.

  8. Carbon nanotube-based coatings on titanium

    Indian Academy of Sciences (India)

    Elzbieta Dlugon; Wojciech Simka; Aneta Fraczek-Szczypta; Wiktor Niemiec; Jaroslaw Markowski; Marzena Szymanska; Marta Blazewicz

    2015-09-01

    This paper reports results of the modification of titanium surface with multiwalled carbon nanotubes (CNTs). The Ti samples were covered with CNTs via electrophoretic deposition (EPD) process. Prior to EPD process, CNTs were functionalized by chemical treatment. Mechanical, electrochemical and biological properties of CNT-covered Ti samples were studied and compared to those obtained for unmodified titanium surface. Atomic force microscopy was used to investigate the surface topography. To determine micromechanical characteristics of CNT-covered metallic samples indentation tests were conducted. Throughout electrochemical studies were performed in order to characterize the impact of the coating on the corrosion of titanium substrate. In vitro experiments were conducted using the human osteoblast NHOst cell line. CNT layers shielded titanium from corrosion gave the surface-enhanced biointegrative properties. Cells proliferated better on the modified surface in comparison to unmodified titanium. The deposited layer enhanced cell adhesion and spreading as compared to titanium sample.

  9. Carbon Nanotube-Based Chemical Sensors.

    Science.gov (United States)

    Meyyappan, M

    2016-04-27

    The need to sense gases and vapors arises in numerous scenarios in industrial, environmental, security and medical applications. Traditionally, this activity has utilized bulky instruments to obtain both qualitative and quantitative information on the constituents of the gas mixture. It is ideal to use sensors for this purpose since they are smaller in size and less expensive; however, their performance in the field must match that of established analytical instruments in order to gain acceptance. In this regard, nanomaterials as sensing media offer advantages in sensitivity, preparation of chip-based sensors and construction of electronic nose for selective detection of analytes of interest. This article provides a review of the use of carbon nanotubes in gas and vapor sensing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Carbon-Nanotube-Based Chemical Gas Sensor

    Science.gov (United States)

    Kaul, Arunpama B.

    2010-01-01

    Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

  11. Carbon nanotube based NEMS actuators and sensors

    Science.gov (United States)

    Forney, Michael; Poler, Jordan

    2011-03-01

    Single-walled carbon nanotubes (SWNTs) have been widely studied due to superior mechanical and electrical properties. We have grown vertically aligned SWNTs (VA-SWNTs) onto microcantilever (MC) arrays, which provides an architecture for novel actuators and sensors. Raman spectroscopy confirms that the CVD-grown nanotubes are SWNTs and SEM confirms aligned growth. As an actuator, this hybrid MC/VA-SWNT system can be electrostatically modulated. SWNTs are excellent electron acceptors, so we can charge up the VA-SWNT array by applying a voltage. The electrostatic repulsion among the charged SWNTs provides a surface stress that induces MC deflection. Simulation results show that a few electrons per SWNT are needed for measureable deflections, and experimental actuators are being characterized by SEM, Raman, and an AFM optical lever system. The applied voltage is sinusoidally modulated, and deflection is measured with a lock-in amplifier. These actuators could be used for nano-manipulation, release of drugs from a capsule, or nano-valves. As a sensor, this MC/VA-SWNT system offers an improved sensitivity for chemical and bio-sensing compared to surface functionalized MC-based sensors. Those sensors only have a 2D sensing surface, but a MC/VA-SWNT system has significantly more sensing surface because the VA-SWNTs extend microns off the MC surface.

  12. Pristine carbon nanotubes based resistive temperature sensor

    Science.gov (United States)

    Alam, Md Bayazeed; Saini, Sudhir Kumar; Sharma, Daya Shankar; Agarwal, Pankaj B.

    2016-04-01

    A good sensor must be highly sensitive, faster in response, of low cost cum easily producible, and highly reliable. Incorporation of nano-dimensional particles/ wires makes conventional sensors more effective in terms of fulfilling the above requirements. For example, Carbon Nanotubes (CNTs) are promising sensing element because of its large aspect ratio, unique electronic and thermal properties. In addition to their use for widely reported chemical sensing, it has also been explored for temperature sensing. This paper presents the fabrication of CNTs based temperature sensor, prepared on silicon substrate using low cost spray coating method, which is reliable and reproducible method to prepare uniform CNTs thin films on any substrate. Besides this, simple and inexpensive method of preparation of dispersion of single walled CNTs (SWNTs) in 1,2 dichlorobenzene by using probe type ultrasonicator for debundling the CNTs for improving sensor response were used. The electrical contacts over the dispersed SWNTs were taken using silver paste electrodes. Fabricated sensors clearly show immediate change in resistance as a response to change in temperature of SWNTs. The measured sensitivity (change in resistance with temperature) of the sensor was found ˜ 0.29%/°C in the 25°C to 60°C temperature range.

  13. Three-dimensional carbon nanotube based photovoltaics

    Science.gov (United States)

    Flicker, Jack

    2011-12-01

    Photovoltaic (PV) cells with a three dimensional (3D) morphology are an exciting new research thrust with promise to create cheaper, more efficient solar cells. This work introduces a new type of 3D PV device based on carbon nanotube (CNT) arrays. These arrays are paired with the thin film heterojunction, CdTe/CdS, to form a complete 3D carbon nanotube PV device (3DCNTPV). Marriage of a complicated 3D structure with production methods traditionally used for planar CdTe solar cell is challenging. This work examines the problems associated with processing these types of cells and systematically alters production methods of the semiconductor layers and electrodes to increase the short circuit current (Isc), eliminate parasitic shunts, and increase the open circuit voltage (Voc). The main benefit of 3D solar cell is the ability to utilize multiple photon interactions with the solar cell surface. The three dimensionality allows photons to interact multiple times with the photoactive material, which increases the absorption and the overall power output over what is possible with a two dimensional (2D) morphology. To quantify the increased power output arising from these multiple photon interactions, a new absorption efficiency term, eta3D, is introduced. The theoretical basis behind this new term and how it relates to the absorption efficiency of a planar cell, eta 2D, is derived. A unique model for the average number of multiple photon impingements, Gamma, is proposed based on three categories of 3D morphology: an infinite trench, an enclosed box, and an array of towers. The derivation of eta3D and Gamma for these 3D PV devices gives a complete picture of the enhanced power output over 2D cells based on CNT array height, pitch, radius, and shape. This theory is validated by monte carlo simulations and experiment. This new type of 3D PV devices has been shown to work experimentally. The first 3DCNTPV cells created posses Isc values of 0.085 to 17.872mA/cm2 and Voc values

  14. Carbon-Nanotube-Based Electrodes for Biomedical Applications

    Science.gov (United States)

    Li, Jun; Meyyappan, M.

    2008-01-01

    A nanotube array based on vertically aligned nanotubes or carbon nanofibers has been invented for use in localized electrical stimulation and recording of electrical responses in selected regions of an animal body, especially including the brain. There are numerous established, emerging, and potential applications for localized electrical stimulation and/or recording, including treatment of Parkinson s disease, Tourette s syndrome, and chronic pain, and research on electrochemical effects involved in neurotransmission. Carbon-nanotube-based electrodes offer potential advantages over metal macroelectrodes (having diameters of the order of a millimeter) and microelectrodes (having various diameters ranging down to tens of microns) heretofore used in such applications. These advantages include the following: a) Stimuli and responses could be localized at finer scales of spatial and temporal resolution, which is at subcellular level, with fewer disturbances to, and less interference from, adjacent regions. b) There would be less risk of hemorrhage on implantation because nano-electrode-based probe tips could be configured to be less traumatic. c) Being more biocompatible than are metal electrodes, carbon-nanotube-based electrodes and arrays would be more suitable for long-term or permanent implantation. d) Unlike macro- and microelectrodes, a nano-electrode could penetrate a cell membrane with minimal disruption. Thus, for example, a nanoelectrode could be used to generate an action potential inside a neuron or in proximity of an active neuron zone. Such stimulation may be much more effective than is extra- or intracellular stimulation via a macro- or microelectrode. e) The large surface area of an array at a micron-scale footprint of non-insulated nanoelectrodes coated with a suitable electrochemically active material containing redox ingredients would make it possible to obtain a pseudocapacitance large enough to dissipate a relatively large amount of electric charge

  15. Gecko-inspired carbon nanotube-based self-cleaning adhesives.

    Science.gov (United States)

    Sethi, Sunny; Ge, Liehui; Ci, Lijie; Ajayan, P M; Dhinojwala, Ali

    2008-03-01

    The design of reversible adhesives requires both stickiness and the ability to remain clean from dust and other contaminants. Inspired by gecko feet, we demonstrate the self-cleaning ability of carbon nanotube-based flexible gecko tapes.

  16. Systems and Methods for Fabricating Carbon Nanotube-Based Vacuum Electronic Devices

    Science.gov (United States)

    Manohara, Harish (Inventor); Toda, Risaku (Inventor); Del Castillo, Linda Y. (Inventor); Murthy, Rakesh (Inventor)

    2015-01-01

    Systems and methods in accordance with embodiments of the invention proficiently produce carbon nanotube-based vacuum electronic devices. In one embodiment a method of fabricating a carbon nanotube-based vacuum electronic device includes: growing carbon nanotubes onto a substrate to form a cathode; assembling a stack that includes the cathode, an anode, and a first layer that includes an alignment slot; disposing a microsphere partially into the alignment slot during the assembling of the stack such that the microsphere protrudes from the alignment slot and can thereby separate the first layer from an adjacent layer; and encasing the stack in a vacuum sealed container.

  17. A new nonlinear model for analyzing the behaviour of carbon nanotube-based resonators

    Science.gov (United States)

    Farokhi, Hamed; Païdoussis, Michael P.; Misra, Arun K.

    2016-09-01

    The present study develops a new size-dependent nonlinear model for the analysis of the behaviour of carbon nanotube-based resonators. In particular, based on modified couple stress theory, the fully nonlinear equations of motion of the carbon nanotube-based resonator are derived using Hamilton's principle, taking into account both the longitudinal and transverse displacements. Molecular dynamics simulation is then performed in order to verify the validity of the developed size-dependent continuum model at the nano scale. The nonlinear partial differential equations of motion of the system are discretized by means of the Galerkin technique, resulting in a high-dimensional reduced-order model of the system. The pseudo-arclength continuation technique is employed to examine the nonlinear resonant behaviour of the carbon nanotube-based resonator. A new universal pull-in formula is also developed for predicting the occurrence of the static pull-in and validated using numerical simulations.

  18. Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

    Science.gov (United States)

    Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H

    2014-04-01

    A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an aqueous media or other media to form a suspension, adding reactants and catalyst to the suspension to create a reaction mixture, curing the reaction mixture to form a wet gel, drying the wet gel to produce a dry gel, and pyrolyzing the dry gel to produce the mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel. The aerogel is mechanically robust, electrically conductive, and ultralow-density, and is made of a porous carbon material having 5 to 95% by weight carbon nanotubes and 5 to 95% carbon binder.

  19. Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr, Joe H.

    2016-07-05

    A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an aqueous media or other media to form a suspension, adding reactants and catalyst to the suspension to create a reaction mixture, curing the reaction mixture to form a wet gel, drying the wet gel to produce a dry gel, and pyrolyzing the dry gel to produce the mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel. The aerogel is mechanically robust, electrically conductive, and ultralow-density, and is made of a porous carbon material having 5 to 95% by weight carbon nanotubes and 5 to 95% carbon binder.

  20. On the elastic properties of carbon nanotube-based composites: modelling and characterization

    CERN Document Server

    Thostenson, E T

    2003-01-01

    The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon nanotube strongly influences the overall properties of the composite. The focus of this research is to develop a fundamental understanding of the structure/size influence of carbon nanotubes on the elastic properties of nanotube-based composites. Towards this end, the nanoscale structure and elastic properties of a model composite system of aligned multi-walled carbon nanotubes embedded in a polystyrene matrix were characterized, and a micromechanical approach for modelling of short fibre composites was modified to account for the structure of the nanotube reinforcement to predict the elastic modulus of the nanocomposite as a function of the constituent properties, reinforcement geometry and nanot...

  1. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  2. Systems and Methods for Implementing Robust Carbon Nanotube-Based Field Emitters

    Science.gov (United States)

    Manohara, Harish (Inventor); Kristof, Valerie (Inventor); Toda, Risaku (Inventor)

    2015-01-01

    Systems and methods in accordance with embodiments of the invention implement carbon nanotube-based field emitters. In one embodiment, a method of fabricating a carbon nanotube field emitter includes: patterning a substrate with a catalyst, where the substrate has thereon disposed a diffusion barrier layer; growing a plurality of carbon nanotubes on at least a portion of the patterned catalyst; and heating the substrate to an extent where it begins to soften such that at least a portion of at least one carbon nanotube becomes enveloped by the softened substrate.

  3. Carbon nanotube based stationary phases for microchip chromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kutter, Jörg Peter

    2012-01-01

    The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have...... already been demonstrated in more classical formats, for improved separation performance in gas and liquid chromatography, and for unique applications in solid phase extraction. Carbon nanotubes are now also entering the field of microfluidics, where there is a large potential to be able to provide...... integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels. An evaluation of the different implementations of carbon nanotubes and related carbon-based nanomaterials for microfluidic chromatography devices is given in terms of separation performance...

  4. Carbon Nanotube Based Microfluidic Elements for Filtration and Concentration

    Energy Technology Data Exchange (ETDEWEB)

    Bakajin, O; Ben-Barak, N; Peng, J; Noy, A

    2003-06-25

    We have developed a method for integration of patterned arrays of carbon nanotubes or the ''nanotube mesh'' into microfabricated channels. The method includes standard lithographic methods for patterning and etching the substrate, followed by catalyst patterning, CVD deposition of nanotubes, and anodic bonding of coverslip top. We will describe a carbon nanotube filtering device fabricated using this method and discuss the use of carbon nanotube arrays as molecular concentration and separation media.

  5. Carbon nanotube-based functional materials for optical limiting.

    Science.gov (United States)

    Chen, Yu; Lin, Ying; Liu, Ying; Doyle, James; He, Nan; Zhuang, Xiaodong; Bai, Jinrui; Blau, Werner J

    2007-01-01

    Optical limiting is an important application of nonlinear optics, useful for the protection of human eyes, optical elements, and optical sensors from intense laser pulses. An optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The optical limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent optical limiting responses. In the former case the optical limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real optical limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The optical limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the optical limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the optical limiting. Further improvements in the optical limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by

  6. Carbon nanotube-based separation columns for microchip electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, K. B.; Delacourt, B.; Kutter, Jörg P.

    2015-01-01

    the fabrication and operation protocols for devices with microfabricated carbon nanotube stationary phases for reversephase chromatography. In this protocol, the lithographically defined stationary phase is fabricated in the channel before bonding of a lid, thereby circumventing the difficult packaging procedures...

  7. Roll-to-Roll production of carbon nanotubes based supercapacitors

    Science.gov (United States)

    Zhu, Jingyi; Childress, Anthony; Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Podila, Ramakrishna; Rao, Apparao

    2014-03-01

    Carbon nanomaterials provide an excellent platform for electrochemical double layer capacitors (EDLCs). However, current industrial methods for producing carbon nanotubes are expensive and thereby increase the costs of energy storage to more than 10 Wh/kg. In this regard, we developed a facile roll-to-roll production technology for scalable manufacturing of multi-walled carbon nanotubes (MWNTs) with variable density on run-of-the-mill kitchen Al foils. Our method produces MWNTs with diameter (heights) between 50-100 nm (10-100 μm), and a specific capacitance as high as ~ 100 F/g in non-aqueous electrolytes. In this talk, the fundamental challenges involved in EDLC-suitable MWNT growth, roll-to-roll production, and device manufacturing will be discussed along with electrochemical characteristics of roll-to-roll MWNTs. Research supported by NSF CMMI Grant1246800.

  8. Carbon nanotube-based superconducting and ferromagnetic hybrid systems

    NARCIS (Netherlands)

    Man, H.T.

    2006-01-01

    Carbon Nanotubes are molecules with exceptional physical properties that are most useful for applications in the growing field of nanotechnology. In addition, because of its special electrical properties, they are extremely useful for experiments on the fundamental properties of one-dimensional elec

  9. Carbon Nanotube-Based Separation Columns for Microchip Electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Delacourt, B.; Kutter, Jörg Peter

    2015-01-01

    the fabrication and operation protocols for devices with microfabricated carbon nanotube stationary phases for reverse-phase chromatography. In this protocol, the lithographically defined stationary phase is fabricated in the channel before bonding of a lid, thereby circumventing the difficult packaging...

  10. Carbon nanotube-based heterostructures for solar energy applications.

    Science.gov (United States)

    Wang, Lei; Liu, Haiqing; Konik, Robert M; Misewich, James A; Wong, Stanislaus S

    2013-10-21

    One means of combining the unique physical and chemical properties of both carbon nanotubes and complementary material motifs (such as metal sulfide quantum dots (QDs), metal oxide nanostructures, and polymers) can be achieved by generating carbon nanotube (CNT)-based heterostructures. These materials can be subsequently utilized as novel and interesting constituent building blocks for the assembly of functional light energy harvesting devices and because of their architectural and functional flexibility, can potentially open up novel means of using and taking advantage of existing renewable energy sources. In this review, we present the reliable and reproducible synthesis of several unique model CNT-based heterostructured systems as well as include an accompanying discussion about the charge transfer and energy flow properties of these materials for their potential incorporation into a range of practical solar energy conversion devices.

  11. Carbon Nanotubes Based Glucose Needle-type Biosensor

    Directory of Open Access Journals (Sweden)

    Hong Li

    2008-03-01

    Full Text Available A novel needle-type biosensor based on carbon nanotubes is reported. Thebiosensor was prepared by packing a mixture of multi-wall carbon nanotubes (MWCNTs,graphite powder and glucose oxidase (Gox freeze-dried powder into a glass capillary of 0.5mm inner diameter. The resulting amperometric biosensor was characterizedelectrochemically using amperometry in the presence of hydrogen peroxide and in thepresence of glucose. The glucose biosensor sensitivity was influenced by the glucoseoxidase concentration within the MWCNTs mixture. The optimized glucose needle-typebiosensor displayed better sensitivity and stability, and a detected range of up to 20 mM.Based on its favorable stability, the needle biosensor was first time used in real-timemonitoring system as a kind of online glucose detector. The decay of current response isless than 10% after 24-hour continuous observation.

  12. Carbon Nanotube Based Groundwater Remediation: The Case of Trichloroethylene

    OpenAIRE

    Kshitij C. Jha; Zhuonan Liu; Hema Vijwani; Mallikarjuna Nadagouda; Mukhopadhyay, Sharmila M.; Mesfin Tsige

    2016-01-01

    Adsorption of chlorinated organic contaminants (COCs) on carbon nanotubes (CNTs) has been gaining ground as a remedial platform for groundwater treatment. Applications depend on our mechanistic understanding of COC adsorption on CNTs. This paper lays out the nature of competing interactions at play in hybrid, membrane, and pure CNT based systems and presents results with the perspective of existing gaps in design strategies. First, current remediation approaches to trichloroethylene (TCE), th...

  13. Single Wall Carbon Nanotubes Based Cryogenic Temperature Sensor Platforms.

    Science.gov (United States)

    Monea, Bogdan Florian; Ionete, Eusebiu Ilarian; Spiridon, Stefan Ionut; Leca, Aurel; Stanciu, Anda; Petre, Emil; Vaseashta, Ashok

    2017-09-10

    We present an investigation consisting of single walled carbon nanotubes (SWCNTs) based cryogenic temperature sensors, capable of measuring temperatures in the range of 2-77 K. Carbon nanotubes (CNTs) due to their extremely small size, superior thermal and electrical properties have suggested that it is possible to create devices that will meet necessary requirements for miniaturization and better performance, by comparison to temperature sensors currently available on the market. Starting from SWCNTs, as starting material, a resistive structure was designed. Employing dropcast method, the carbon nanotubes were deposited over pairs of gold electrodes and in between the structure electrodes from a solution. The procedure was followed by an alignment process between the electrodes using a dielectrophoretic method. Two sensor structures were tested in cryogenic field down to 2 K, and the resistance was measured using a standard four-point method. The measurement results suggest that, at temperatures below 20 K, the temperature coefficient of resistance average for sensor 1 is 1.473%/K and for sensor 2 is 0.365%/K. From the experimental data, it can be concluded that the dependence of electrical resistance versus temperature can be approximated by an exponential equation and, correspondingly, a set of coefficients are calculated. It is further concluded that the proposed approach described here offers several advantages, which can be employed in the fabrication of a microsensors for cryogenic applications.

  14. Carbon nanotube based gecko inspired self-cleaning adhesives

    Science.gov (United States)

    Sethi, Sunny; Ge, Liehui; Ajayan, Pulickel; Ali, Dhinojwala

    2008-03-01

    Wall climbing organisms like geckos have unique ability to attach to different surfaces without use of any viscoelastic material. The hairy structure found in gecko feet allows them to obtain intimate contact over a large area thus allowing then to adhere using van der Waals interactions. Not only high adhesion, the geometry of the hairs makes gecko feet self cleaning, thus allowing them to walk continuously without worrying about loosing adhesive strength. Such properties if mimicked synthetically could form basis of a new class of materials, which, unlike conventional adhesives would show two contradictory properties, self cleaning and high adhesion. Such materials would form essential component of applications like wall climbing robot. We tried to synthesize such material using micropatterened vertically aligned carbon nanotubes. When dealing with large areas, probability of defects in the structure increase, forming patterns instead of using uniform film of carbon nanotubes helps to inhibit crack propagation, thus gives much higher adhesive strength than a uniform film. When carbon nanotube patterns with optimized aspect ratio are used, both high adhesion and self cleaning properties are observed.

  15. Monitoring Mechanical Motion of Carbon Nanotube based Nanomotor by Optical Absorption Spectrum

    CERN Document Server

    Wang, Baomin; Wang, Zhan; Wang, Yong; Liu, Kaihui

    2016-01-01

    The optical absorption spectrums of nanomotors made from double-wall carbon nanotubes have been calculated with the time-dependent density functional based tight binding method. When the outer short tube of the nanomotor moves along or rotates around the inner long tube, the peaks in the spectrum will gradually evolve and may shift periodically, the amplitude of which can be as large as hundreds of meV. We show that the features and behaviors of the optical absorption spectrum could be used to monitor the mechanical motions of the double-wall carbon nanotube based nanomotor.

  16. Heat dissipation for microprocessor using multiwalled carbon nanotubes based liquid.

    Science.gov (United States)

    Hung Thang, Bui; Trinh, Pham Van; Chuc, Nguyen Van; Khoi, Phan Hong; Minh, Phan Ngoc

    2013-01-01

    Carbon nanotubes (CNTs) are one of the most valuable materials with high thermal conductivity (2000 W/m · K compared with thermal conductivity of Ag 419 W/m · K). This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED). In this work, multiwalled carbon nanotubes (MWCNTs) based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU's temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU's temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ -processor and other high power electronic devices.

  17. Carbon Nanotube Based Chemical Sensors for Space and Terrestrial Applications

    Science.gov (United States)

    Li, Jing; Lu, Yijiang

    2009-01-01

    A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs), on a pair of interdigitated electrodes (IDE) processed with a silicon-based microfabrication and micromachining technique. The IDE fingers were fabricated using photolithography and thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to nitrogen dioxide, acetone, benzene, nitrotoluene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing of carbon nanotubes in our sensor platform can be understood by intra- and inter-tube electron modulation in terms of charge transfer mechanisms. As a result of the charge transfer, the conductance of p-type or hole-richer SWNTs in air will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost. Additionally, a wireless capability of such a sensor chip can be used for networked mobile and fixed-site detection and warning systems for military bases, facilities and battlefield areas.

  18. Heat Dissipation for Microprocessor Using Multiwalled Carbon Nanotubes Based Liquid

    Directory of Open Access Journals (Sweden)

    Bui Hung Thang

    2013-01-01

    Full Text Available Carbon nanotubes (CNTs are one of the most valuable materials with high thermal conductivity (2000 W/m·K compared with thermal conductivity of Ag 419 W/m·K. This suggested an approach in applying the CNTs in thermal dissipation system for high power electronic devices, such as computer processor and high brightness light emitting diode (HB-LED. In this work, multiwalled carbon nanotubes (MWCNTs based liquid was made by COOH functionalized MWCNTs dispersed in distilled water with concentration in the range between 0.2 and 1.2 gram/liter. MWCNT based liquid was used in liquid cooling system to enhance thermal dissipation for computer processor. By using distilled water in liquid cooling system, CPU’s temperature decreases by about 10°C compared with using fan cooling system. By using MWCNT liquid with concentration of 1 gram/liter MWCNTs, the CPU’s temperature decreases by 7°C compared with using distilled water in cooling system. Theoretically, we also showed that the presence of MWCNTs reduced thermal resistance and increased the thermal conductivity of liquid cooling system. The results have confirmed the advantages of the MWCNTs for thermal dissipation systems for the μ-processor and other high power electronic devices.

  19. Predicting the effective thermal conductivity of carbon nanotube based nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Sastry, N N Venkata; Bhunia, Avijit; Sundararajan, T; Das, Sarit K [Department of Mechanical Engineering, Indian Institute of Technology, Madras, Chennai 600 036 (India)

    2008-02-06

    Adding a small volume fraction of carbon nanotubes (CNTs) to a liquid enhances the thermal conductivity significantly. Recent experimental findings report an anomalously wide range of enhancement values that continue to perplex the research community and remain unexplained. In this paper we present a theoretical model based on three-dimensional CNT chain formation (percolation) in the base liquid and the corresponding thermal resistance network. The model considers random CNT orientation and CNT-CNT interaction forming the percolating chain. Predictions are in good agreement with almost all available experimental data. Results show that the enhancement critically depends on the CNT geometry (length), volume fraction, thermal conductivity of the base liquid and the nanofluid (CNT-liquid suspension) preparation technique. Based on the physical mechanism of heat conduction in the nanofluid, we introduce a new dimensionless parameter that alone characterizes the nanofluid thermal conductivity with reasonable accuracy ({approx} {+-} 5%)

  20. Predicting the effective thermal conductivity of carbon nanotube based nanofluids.

    Science.gov (United States)

    Venkata Sastry, N N; Bhunia, Avijit; Sundararajan, T; Das, Sarit K

    2008-02-06

    Adding a small volume fraction of carbon nanotubes (CNTs) to a liquid enhances the thermal conductivity significantly. Recent experimental findings report an anomalously wide range of enhancement values that continue to perplex the research community and remain unexplained. In this paper we present a theoretical model based on three-dimensional CNT chain formation (percolation) in the base liquid and the corresponding thermal resistance network. The model considers random CNT orientation and CNT-CNT interaction forming the percolating chain. Predictions are in good agreement with almost all available experimental data. Results show that the enhancement critically depends on the CNT geometry (length), volume fraction, thermal conductivity of the base liquid and the nanofluid (CNT-liquid suspension) preparation technique. Based on the physical mechanism of heat conduction in the nanofluid, we introduce a new dimensionless parameter that alone characterizes the nanofluid thermal conductivity with reasonable accuracy (∼ ± 5%).

  1. A carbon nanotube based ammonia sensor on cotton textile

    Science.gov (United States)

    Han, Jin-Woo; Kim, Beomseok; Li, Jing; Meyyappan, M.

    2013-05-01

    A single-wall carbon nanotube (CNT) based ammonia (NH3) sensor was implemented on a cotton yarn. Two types of sensors were fabricated: Au/sensing CNT/Au and conducting/sensing/conducting all CNT structures. Two perpendicular Au wires were designed to contact CNT-cotton yarn for metal-CNT sensor, whereas nanotubes were used for the electrode as well as sensing material for the all CNT sensor. The resistance shift of the CNT network upon NH3 was monitored in a chemiresistor approach. The CNT-cotton yarn sensors exhibited uniformity and repeatability. Furthermore, the sensors displayed good mechanical robustness against bending. The present approach can be utilized for low-cost smart textile applications.

  2. 3D Printing of Carbon Nanotubes-Based Microsupercapacitors.

    Science.gov (United States)

    Yu, Wei; Zhou, Han; Li, Ben Q; Ding, Shujiang

    2017-02-08

    A novel 3D printing procedure is presented for fabricating carbon-nanotubes (CNTs)-based microsupercapacitors. The 3D printer uses a CNTs ink slurry with a moderate solid content and prints a stream of continuous droplets. Appropriate control of a heated base is applied to facilitate the solvent removal and adhesion between printed layers and to improve the structure integrity without structure delamination or distortion upon drying. The 3D-printed electrodes for microsupercapacitors are characterized by SEM, laser scanning confocal microscope, and step profiler. Effect of process parameters on 3D printing is also studied. The final solid-state microsupercapacitors are assembled with the printed multilayer CNTs structures and poly(vinyl alcohol)-H3PO4 gel as the interdigitated microelectrodes and electrolyte. The electrochemical performance of 3D printed microsupercapacitors is also tested, showing a significant areal capacitance and excellent cycle stability.

  3. Recent advances in Carbon Nanotube based Enzymatic Fuel Cells

    Directory of Open Access Journals (Sweden)

    Serge eCosnier

    2014-10-01

    Full Text Available This review summarizes recent trends in the field of enzymatic fuel cells. Thanks to the high specificity of enzymes, biofuel cells can generate electrical energy by oxidation of a targeted fuel (sugars, alcohols or hydrogen at the anode and reduction of oxidants (O2, H2O2 at the cathode in complex media. The combination of carbon nanotubes, enzymes and redox mediators was widely exploited to develop biofuel cells since the electrons, involved in the bio-electrocatalytic processes, can be efficiently transferred from or to an external circuit. Original approaches to construct electron transfer based CNT-bioelectrodes and impressive biofuel cell performances are reported as well as biomedical applications.

  4. Carbon Nanotube Based Groundwater Remediation: The Case of Trichloroethylene.

    Science.gov (United States)

    Jha, Kshitij C; Liu, Zhuonan; Vijwani, Hema; Nadagouda, Mallikarjuna; Mukhopadhyay, Sharmila M; Tsige, Mesfin

    2016-07-21

    Adsorption of chlorinated organic contaminants (COCs) on carbon nanotubes (CNTs) has been gaining ground as a remedial platform for groundwater treatment. Applications depend on our mechanistic understanding of COC adsorption on CNTs. This paper lays out the nature of competing interactions at play in hybrid, membrane, and pure CNT based systems and presents results with the perspective of existing gaps in design strategies. First, current remediation approaches to trichloroethylene (TCE), the most ubiquitous of the COCs, is presented along with examination of forces contributing to adsorption of analogous contaminants at the molecular level. Second, we present results on TCE adsorption and remediation on pure and hybrid CNT systems with a stress on the specific nature of substrate and molecular architecture that would contribute to competitive adsorption. The delineation of intermolecular interactions that contribute to efficient remediation is needed for custom, scalable field design of purification systems for a wide range of contaminants.

  5. Carbon Nanotube Based Groundwater Remediation: The Case of Trichloroethylene

    Directory of Open Access Journals (Sweden)

    Kshitij C. Jha

    2016-07-01

    Full Text Available Adsorption of chlorinated organic contaminants (COCs on carbon nanotubes (CNTs has been gaining ground as a remedial platform for groundwater treatment. Applications depend on our mechanistic understanding of COC adsorption on CNTs. This paper lays out the nature of competing interactions at play in hybrid, membrane, and pure CNT based systems and presents results with the perspective of existing gaps in design strategies. First, current remediation approaches to trichloroethylene (TCE, the most ubiquitous of the COCs, is presented along with examination of forces contributing to adsorption of analogous contaminants at the molecular level. Second, we present results on TCE adsorption and remediation on pure and hybrid CNT systems with a stress on the specific nature of substrate and molecular architecture that would contribute to competitive adsorption. The delineation of intermolecular interactions that contribute to efficient remediation is needed for custom, scalable field design of purification systems for a wide range of contaminants.

  6. Carbon nanotube based sensors and fluctuation enhanced sensing

    Energy Technology Data Exchange (ETDEWEB)

    Kukovecz, Akos; Konya, Zoltan; Haspel, Henrik; Mohl, Melinda; Sapi, Andras; Kiricsi, Imre [Department of Applied and Environmental Chemistry, University of Szeged (Hungary); Molnar, Daniel; Heszler, Peter [Research Group on Laser Physics of the Hungarian Academy of Sciences, University of Szeged (Hungary); Kordas, Krisztian; Maeklin, Jani; Halonen, Niina; Toth, Geza [Microelectronics and Materials Physics Laboratories, and EMPART Research Group of Infotech Oulu, University of Oulu (Finland); Gingl, Zoltan; Mingesz, Robert [Department of Experimental Physics, University of Szeged (Hungary); Moilanen, Hannu [Laserprobe LP Ltd., Oulu (Finland); Roth, Siegmar [Max Planck Institute for Solid State Research, Stuttgart (Germany); Vajtai, Robert; Ajayan, Pulickel M. [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX (United States); Pouillon, Yann; Rubio, Angel [Nano-Bio Spectroscopy Group y ETSF Scientific Development Centre, Dpto. Fisica de Materiales, Universidad del Pais Vasco, Centro de Fisica de Materiales CSIC-UPV/EHU-MPC y DIPC, San Sebastian (Spain)

    2010-04-15

    Drop-cast thin films of multi-walled carbon nanotubes are used as gas sensors in a four-probe measurement setup. The novelty of the approach is that the sensor information is extracted from the noise of the dc resistance data using Fluctuation Enhanced Sensing (FES). We investigate the effects of measurement duration, gate voltage and frequency window on the chemical selectivity of the MWCNT-FES sensor. The selectivity of the device is superior to those of conventional gas sensors, and preliminary experiments indicate that it may also be possible to extract quantitative information from the noise. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. A carbon nanotube based x-ray detector

    Science.gov (United States)

    Boucher, Richard A.; Bauch, Jürgen; Wünsche, Dietmar; Lackner, Gerhard; Majumder, Anindya

    2016-11-01

    X-ray detectors based on metal-oxide semiconductor field effect transistors couple instantaneous measurement with high accuracy. However, they only have a limited measurement lifetime because they undergo permanent degradation due to x-ray beam exposure. A field effect transistor based on carbon nanotubes (CNTs), however, overcomes this drawback of permanent degradation, because it can be reset into its starting state after being exposed to the x-ray beam. In this work the CNTs were deposited using a dielectrophoresis method on SiO2 coated p-type (boron-doped) Si substrates. For the prepared devices a best gate voltage shift of 244 V Gy-1 and a source-drain current sensitivity of 382 nA Gy-1 were achieved. These values are larger than those reached by the currently used MOSFET based devices.

  8. Actuation mechanisms of carbon nanotube-based architectures

    Science.gov (United States)

    Geier, Sebastian; Mahrholz, Thorsten; Wierach, Peter; Sinapius, Michael

    2016-04-01

    State of the art smart materials such as piezo ceramics or electroactive polymers cannot feature both, mechanical stiffness and high active strain. Moreover, properties like low density, high mechanical stiffness and high strain at the same time driven by low energy play an increasingly important role for their future application. Carbon nanotubes (CNT), show this behavior. Their active behavior was observed 1999 the first time using paper-like mats made of CNT. Therefore the CNT-papers are electrical charged within an electrolyte thus forming a double- layer. The measured deflection of CNT material is based on the interaction between the charged high surface area formed by carbon nanotubes and ions provided by the electrolyte. Although CNT-papers have been extensively analyzed as well at the macro-scale as nano-scale there is still no generally accepted theory for the actuation mechanism. This paper focuses on investigations of the actuation mechanisms of CNT-papers in comparison to vertically aligned CNT-arrays. One reason of divergent results found in literature might be attributed to different types of CNT samples. While CNT-papers represent architectures of short CNTs which need to bridge each other to form the dimensions of the sample, the continuous CNTs of the array feature a length of almost 3 mm, along which the experiments are carried out. Both sample types are tested within an actuated tensile test set-up under different conditions. While the CNT-papers are tested in water-based electrolytes with comparably small redox-windows the hydrophobic CNT-arrays are tested in ionic liquids with comparatively larger redox-ranges. Furthermore an in-situ micro tensile test within an SEM is carried out to prove the optimized orientation of the MWCNTs as result of external load. It was found that the performance of CNT-papers strongly depends on the test conditions. However, the CNT-arrays are almost unaffected by the conditions showing active response at negative

  9. Single-Walled Carbon-Nanotubes-Based Organic Memory Structures

    Directory of Open Access Journals (Sweden)

    Sundes Fakher

    2016-09-01

    Full Text Available The electrical behaviour of organic memory structures, based on single-walled carbon-nanotubes (SWCNTs, metal–insulator–semiconductor (MIS and thin film transistor (TFT structures, using poly(methyl methacrylate (PMMA as the gate dielectric, are reported. The drain and source electrodes were fabricated by evaporating 50 nm gold, and the gate electrode was made from 50 nm-evaporated aluminium on a clean glass substrate. Thin films of SWCNTs, embedded within the insulating layer, were used as the floating gate. SWCNTs-based memory devices exhibited clear hysteresis in their electrical characteristics (capacitance–voltage (C–V for MIS structures, as well as output and transfer characteristics for transistors. Both structures were shown to produce reliable and large memory windows by virtue of high capacity and reduced charge leakage. The hysteresis in the output and transfer characteristics, the shifts in the threshold voltage of the transfer characteristics, and the flat-band voltage shift in the MIS structures were attributed to the charging and discharging of the SWCNTs floating gate. Under an appropriate gate bias (1 s pulses, the floating gate is charged and discharged, resulting in significant threshold voltage shifts. Pulses as low as 1 V resulted in clear write and erase states.

  10. Carbon nanotube-based bioceramic grafts for electrotherapy of bone.

    Science.gov (United States)

    Mata, D; Horovistiz, A L; Branco, I; Ferro, M; Ferreira, N M; Belmonte, M; Lopes, M A; Silva, R F; Oliveira, F J

    2014-01-01

    Bone complexity demands the engineering of new scaffolding solutions for its reconstructive surgery. Emerging bone grafts should offer not only mechanical support but also functional properties to explore innovative bone therapies. Following this, ceramic bone grafts of Glass/hydroxyapatite (HA) reinforced with conductive carbon nanotubes (CNTs) - CNT/Glass/HA - were prepared for bone electrotherapy purposes. Computer-aided 3D microstructural reconstructions and TEM analysis of CNT/Glass/HA composites provided details on the CNT 3D network and further correlation to their functional properties. CNTs are arranged as sub-micrometric sized ropes bridging homogenously distributed ellipsoid-shaped agglomerates. This arrangement yielded composites with a percolation threshold of pc=1.5vol.%. At 4.4vol.% of CNTs, thermal and electrical conductivities of 1.5W·m(-1)·K(-1) and 55S·m(-1), respectively, were obtained, matching relevant requisites in electrical stimulation protocols. While the former avoids bone damaging from Joule's heat generation, the latter might allow the confinement of external electrical fields through the conductive material if used for in vivo electrical stimulation. Moreover, the electrically conductive bone grafts have better mechanical properties than those of the natural cortical bone. Overall, these highly conductive materials with controlled size CNT agglomerates might accelerate bone bonding and maximize the delivery of electrical stimulation during electrotherapy practices.

  11. Carbon nanotube-based supercapacitors using low cost collectors

    Science.gov (United States)

    Amirhoseiny, Maryam; Zandi, Majid; Mosayyebi, Abolghasem; Khademian, Mehrzad

    2016-01-01

    In this work, electrochemical double layer supercapacitors were fabricated using multiwalled carbon nanotube (MWCNT) composite microfilm as electrode. To improve the electrochemical properties, MWCNTs were functionalized with -COOH by acid treatments. CNT/PVA films have been deposited on different current collectors by spin coating to drastically enhance the electrode performance. Electrode fabrication involved various stages preparing of the CNT composite, and coating of the CNT/PVA paste on different substrates which also served as current collector. Al, Ni and graphite were used and compared as current collectors. The surface morphology of the fabricated electrodes was investigated with scanning electrode microscopy (SEM). Overall cell performance was evaluated with a multi-channel potentiostat/galvanostat analyzer. Each supercapacitor cell was subjected to charge-discharge cycling study at different current rates from 0.2Ag-1 to 1Ag-1. The results showed that graphite-based electrodes offer advantages of significantly higher conductivity and superior capacitive behavior compared to thin film electrodes formed on Ni and Al current collectors. The specific capacitance of graphite based electrode is found to be 29Fg-1.

  12. Fowler Nordheim theory of carbon nanotube based field emitters

    Science.gov (United States)

    Parveen, Shama; Kumar, Avshish; Husain, Samina; Husain, Mushahid

    2017-01-01

    Field emission (FE) phenomena are generally explained in the frame-work of Fowler Nordheim (FN) theory which was given for flat metal surfaces. In this work, an effort has been made to present the field emission mechanism in carbon nanotubes (CNTs) which have tip type geometry at nanoscale. High aspect ratio of CNTs leads to large field enhancement factor and lower operating voltages because the electric field strength in the vicinity of the nanotubes tip can be enhanced by thousand times. The work function of nanostructure by using FN plot has been calculated with reverse engineering. With the help of modified FN equation, an important formula for effective emitting area (active area for emission of electrons) has been derived and employed to calculate the active emitting area for CNT field emitters. Therefore, it is of great interest to present a state of art study on the complete solution of FN equation for CNTs based field emitter displays. This manuscript will also provide a better understanding of calculation of different FE parameters of CNTs field emitters using FN equation.

  13. Carbon Nanotube-Based Structural Health Monitoring Sensors

    Science.gov (United States)

    Wincheski, Russell; Jordan, Jeffrey; Oglesby, Donald; Watkins, Anthony; Patry, JoAnne; Smits, Jan; Williams, Phillip

    2011-01-01

    Carbon nanotube (CNT)-based sensors for structural health monitoring (SHM) can be embedded in structures of all geometries to monitor conditions both inside and at the surface of the structure to continuously sense changes. These CNTs can be manipulated into specific orientations to create small, powerful, and flexible sensors. One of the sensors is a highly flexible sensor for crack growth detection and strain field mapping that features a very dense and highly ordered array of single-walled CNTs. CNT structural health sensors can be mass-produced, are inexpensive, can be packaged in small sizes (0.5 micron(sup 2)), require less power than electronic or piezoelectric transducers, and produce less waste heat per square centimeter than electronic or piezoelectric transducers. Chemically functionalized lithographic patterns are used to deposit and align the CNTs onto metallic electrodes. This method consistently produces aligned CNTs in the defined locations. Using photo- and electron-beam lithography, simple Cr/Au thin-film circuits are patterned onto oxidized silicon substrates. The samples are then re-patterned with a CNT-attracting, self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES) to delineate the desired CNT locations between electrodes. During the deposition of the solution-suspended single- wall CNTs, the application of an electric field to the metallic contacts causes alignment of the CNTs along the field direction. This innovation is a prime candidate for smart skin technologies with applications ranging from military, to aerospace, to private industry.

  14. Molecular dynamics simulations of carbon nanotube-based gears

    Science.gov (United States)

    Han, Jie; Globus, Al; Jaffe, Richard; Deardorff, Glenn

    1997-09-01

    We use a molecular dynamics simulation to investigate the properties and design space of molecular gears fashioned from carbon nanotubes with teeth added via a benzyne reaction known to occur with 0957-4484/8/3/001/img1. Brenner's reactive hydrocarbon potential is used to model interatomic forces within each molecular gear. A Lennard - Jones 6 - 12 potential or the Buckingham 0957-4484/8/3/001/img2 potential plus electrostatic interaction terms are used for intermolecular interactions between gears. A number of gear and gear/shaft configurations are simulated on parallel computers. One gear is powered by forcing the atoms near the end of the nanotube to rotate, and a second gear is allowed to rotate by keeping the atoms near the end of its nanotube constrained to a cylinder. The meshing aromatic gear teeth transfer angular momentum from the powered gear to the driven gear. Results suggest that these gears can operate at up to 50 - 100 GHz in a vacuum at room temperature. The failure mode involves tooth slip, not bond breaking, so failed gears can be returned to operation by lowering the temperature and/or rotation rate.

  15. A Review of Carbon Nanotubes-Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2009-01-01

    Full Text Available Gas sensors have attracted intensive research interest due to the demand of sensitive, fast response, and stable sensors for industry, environmental monitoring, biomedicine, and so forth. The development of nanotechnology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. The extremely high surface-to-volume ratio and hollow structure of nanomaterials is ideal for the adsorption of gas molecules. Particularly, the advent of carbon nanotubes (CNTs has fuelled the inventions of gas sensors that exploit CNTs' unique geometry, morphology, and material properties. Upon exposure to certain gases, the changes in CNTs' properties can be detected by various methods. Therefore, CNTs-based gas sensors and their mechanisms have been widely studied recently. In this paper, a broad but yet in-depth survey of current CNTs-based gas sensing technology is presented. Both experimental works and theoretical simulations are reviewed. The design, fabrication, and the sensing mechanisms of the CNTs-based gas sensors are discussed. The challenges and perspectives of the research are also addressed in this review.

  16. Fowler Nordheim theory of carbon nanotube based field emitters

    Energy Technology Data Exchange (ETDEWEB)

    Parveen, Shama; Kumar, Avshish [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Samina [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (Central University), New Delhi (India); Husain, Mushahid, E-mail: mush_reslab@rediffmail.com [Department of Physics, Jamia Millia Islamia (Central University), New Delhi (India)

    2017-01-15

    Field emission (FE) phenomena are generally explained in the frame-work of Fowler Nordheim (FN) theory which was given for flat metal surfaces. In this work, an effort has been made to present the field emission mechanism in carbon nanotubes (CNTs) which have tip type geometry at nanoscale. High aspect ratio of CNTs leads to large field enhancement factor and lower operating voltages because the electric field strength in the vicinity of the nanotubes tip can be enhanced by thousand times. The work function of nanostructure by using FN plot has been calculated with reverse engineering. With the help of modified FN equation, an important formula for effective emitting area (active area for emission of electrons) has been derived and employed to calculate the active emitting area for CNT field emitters. Therefore, it is of great interest to present a state of art study on the complete solution of FN equation for CNTs based field emitter displays. This manuscript will also provide a better understanding of calculation of different FE parameters of CNTs field emitters using FN equation.

  17. Multi-walled carbon nanotube-based RF antennas.

    Science.gov (United States)

    Elwi, Taha A; Al-Rizzo, Hussain M; Rucker, Daniel G; Dervishi, Enkeleda; Li, Zhongrui; Biris, Alexandru S

    2010-01-29

    A novel application that utilizes conductive patches composed of purified multi-walled carbon nanotubes (MWCNTs) embedded in a sodium cholate composite thin film to create microstrip antennas operating in the microwave frequency regime is proposed. The MWCNTs are suspended in an adhesive solvent to form a conductive ink that is printed on flexible polymer substrates. The DC conductivity of the printed patches was measured by the four probe technique and the complex relative permittivity was measured by an Agilent E5071B probe. The commercial software package, CST Microwave Studio (MWS), was used to simulate the proposed antennas based on the measured constitutive parameters. An excellent agreement of less than 0.2% difference in resonant frequency is shown. Simulated and measured results were also compared against identical microstrip antennas that utilize copper conducting patches. The proposed MWCNT-based antennas demonstrate a 5.6% to 2.2% increase in bandwidth, with respect to their corresponding copper-based prototypes, without significant degradation in gain and/or far-field radiation patterns.

  18. Molecular Dynamics Simulation of Carbon Nanotube Based Gears

    Science.gov (United States)

    Han, Jie; Globus, Al; Jaffe, Richard; Deardorff, Glenn; Chancellor, Marisa K. (Technical Monitor)

    1996-01-01

    We used molecular dynamics to investigate the properties and design space of molecular gears fashioned from carbon nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. One gear was powered by forcing the atoms near the end of the buckytube to rotate, and a second gear was allowed.to rotate by keeping the atoms near the end of its buckytube on a cylinder. The meshing aromatic gear teeth transfer angular momentum from the powered gear to the driven gear. A number of gear and gear/shaft configurations were simulated. Cases in vacuum and with an inert atmosphere were examined. In an extension to molecular dynamics technology, some simulations used a thermostat on the atmosphere while the hydrocarbon gear's temperature was allowed to fluctuate. This models cooling the gears with an atmosphere. Results suggest that these gears can operate at up to 50-100 gigahertz in a vacuum or inert atmosphere at room temperature. The failure mode involves tooth slip, not bond breaking, so failed gears can be returned to operation by lowering temperature and/or rotation rate. Videos and atomic trajectory files in xyz format are presented.

  19. Molecular Dynamics Simulation of Carbon Nanotube Based Gears

    Science.gov (United States)

    Han, Jie; Globus, Al; Jaffe, Richard; Deardorff, Glenn; Chancellor, Marisa K. (Technical Monitor)

    1996-01-01

    We used molecular dynamics to investigate the properties and design space of molecular gears fashioned from carbon nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. One gear was powered by forcing the atoms near the end of the buckytube to rotate, and a second gear was allowed.to rotate by keeping the atoms near the end of its buckytube on a cylinder. The meshing aromatic gear teeth transfer angular momentum from the powered gear to the driven gear. A number of gear and gear/shaft configurations were simulated. Cases in vacuum and with an inert atmosphere were examined. In an extension to molecular dynamics technology, some simulations used a thermostat on the atmosphere while the hydrocarbon gear's temperature was allowed to fluctuate. This models cooling the gears with an atmosphere. Results suggest that these gears can operate at up to 50-100 gigahertz in a vacuum or inert atmosphere at room temperature. The failure mode involves tooth slip, not bond breaking, so failed gears can be returned to operation by lowering temperature and/or rotation rate. Videos and atomic trajectory files in xyz format are presented.

  20. Carbon Nanotube Based Nano-Electro-Mechanical Systems (NEMS)

    Science.gov (United States)

    Han, Jie; Dai, Hongjie; Saini, Subhash

    1998-01-01

    Carbon nanotubes (CNT) enable nanoelectromechanical systems (NEMS) because of their inherent nanostructure, intrinsic electric conductivity and mechanical resilience. The collaborative work between Stanford (experiment) and NASA Ames (theory and simulation) has made progress in two types of CNT based NEMS for nanoelectronics and sensor applications. The CNT tipped scanning probe microscopy (SPM) is a NEMS in which CNT tips are used for nanoscale probing, imaging and manipulating. It showed great improvement in probing surfaces and biological systems over conventional tips. We have recently applied it to write (lithography) and read (image) uniform SiO2 lines on large Si surface area at speed up to 0.5 mm per s. Preliminary work using approximately 10 nm multiwall nanotube tips produced approximately 10 nm structures and showed that the CNT tips didn't wear down when crashed as conventional tips often do. This presents a solution to the long standing tip-wear problem in SPM nanolithography. We have also explored potential of CNT tips in imaging DNA in water. Preliminary experiment using 10 nm CNT tips reached 5 nm resolution. The 1 nm nanolithography and 1 nm DNA imaging can be expected by using approximately 1 nm CNT tips. In contrast to CNT tipped SPM, we also fabricated CNT devices on silicon wafer in which CNTs connect patterned metallic lines on SiO2/Si by a simple chemical vapor deposition process. Using conventional lithography for silicon wafer, we have been able to obtain CNT based transistors and sensors. Investigations of the CNT NEMS as physical, biological and chemical sensors are in progress and will be discussed.

  1. Critical Role of the Sorting Polymer in Carbon Nanotube-Based Minority Carrier Devices

    Energy Technology Data Exchange (ETDEWEB)

    Mallajosyula, Arun T.; Nie, Wanyi; Gupta, Gautam; Blackburn, Jeffrey L.; Doorn, Stephen K.; Mohite, Aditya D.

    2016-12-27

    A prerequisite for carbon nanotube-based optoelectronic devices is the ability to sort them into a pure semiconductor phase. One of the most common sorting routes is enabled through using specific wrapping polymers. Here we show that subtle changes in the polymer structure can have a dramatic influence on the figures of merit of a carbon nanotube-based photovoltaic device. By comparing two commonly used polyfluorenes (PFO and PFO-BPy) for wrapping (7,5) and (6,5) chirality SWCNTs, we demonstrate that they have contrasting effects on the device efficiency. We attribute this to the differences in their ability to efficiently transfer charge. Although PFO may act as an efficient interfacial layer at the anode, PFO-BPy, having the additional pyridine side groups, forms a high resistance layer degrading the device efficiency. By comparing PFO|C60 and C60-only devices, we found that presence of a PFO layer at low optical densities resulted in the increase of all three solar cell parameters, giving nearly an order of magnitude higher efficiency over that of C60-only devices. In addition, with a relatively higher contribution to photocurrent from the PFO-C60 interface, an open circuit voltage of 0.55 V was obtained for PFO-(7,5)-C60 devices. On the other hand, PFO-BPy does not affect the open circuit voltage but drastically reduces the short circuit current density. These results indicate that the charge transport properties and energy levels of the sorting polymers have to be taken into account to fully understand their effect on carbon nanotube-based solar cells.

  2. Considerably improved photovoltaic performance of carbon nanotube-based solar cells using metal oxide layers.

    Science.gov (United States)

    Wang, Feijiu; Kozawa, Daichi; Miyauchi, Yuhei; Hiraoka, Kazushi; Mouri, Shinichiro; Ohno, Yutaka; Matsuda, Kazunari

    2015-02-18

    Carbon nanotube-based solar cells have been extensively studied from the perspective of potential application. Here we demonstrated a significant improvement of the carbon nanotube solar cells by the use of metal oxide layers for efficient carrier transport. The metal oxides also serve as an antireflection layer and an efficient carrier dopant, leading to a reduction in the loss of the incident solar light and an increase in the photocurrent, respectively. As a consequence, the photovoltaic performance of both p-single-walled carbon nanotube (SWNT)/n-Si and n-SWNT/p-Si heterojunction solar cells using MoOx and ZnO layers is improved, resulting in very high photovoltaic conversion efficiencies of 17.0 and 4.0%, respectively. These findings regarding the use of metal oxides as multifunctional layers suggest that metal oxide layers could improve the performance of various electronic devices based on carbon nanotubes.

  3. Novel self-sensing carbon nanotube-based composites for rehabilitation of structural steel members

    Science.gov (United States)

    Ahmed, Shafique; Doshi, Sagar; Schumacher, Thomas; Thostenson, Erik T.; McConnell, Jennifer

    2016-02-01

    Fatigue and fracture are among the most critical forms of damage in metal structures. Fatigue damage can initiate from microscopic defects (e.g., surface scratches, voids in welds, and internal defects) and initiate a crack. Under cyclic loading, these cracks can grow and reach a critical level to trigger fracture of the member which leads to compromised structural integrity and, in some cases, catastrophic failure of the entire structure. In our research, we are investigating a solution using carbon nanotube-based sensing composites, which have the potential to simultaneously rehabilitate and monitor fatigue-cracked structural members. These composites consist of a fiber-reinforced polymer (FRP) layer and a carbon nanotube-based sensing layer, which are integrated to form a novel structural self-sensing material. The sensing layer is composed of a non-woven aramid fabric that is coated with carbon nanotubes (CNT) to form an electrically conductive network that is extremely sensitive to detecting deformation as well as damage accumulation via changes in the resistance of the CNT network. In this paper, we introduce the sensing concept, describe the manufacturing of a model sensing prototype, and discuss a set of small-scale laboratory experiments to examine the load-carrying capacity and damage sensing response.

  4. Carbon nanotube-based sensing devices for human Arginase-1 detection

    Directory of Open Access Journals (Sweden)

    S. Baldo

    2016-03-01

    Full Text Available A new carbon nanotube-based device for detection of Arginase 1 (ARG-1 was produced. Multi-walled carbon nanotubes (MWCNTs were deposited between electrodes by dielectrophoresis (DEP in an accurate and reproducible way. This deposition method has the advantages of low cost and room temperature conditions and therefore, can be used on different kinds of substrates (silicon, glass, plastics allowing for large scale production of chemical or biological sensors. Scanning electrical microscope (SEM and electrical characterization have been performed on the biosensors before and after protein exposure. The devices were tested in the present work for the detection of ARG-1. They show high sensitivity and reproducibility, and can be easily and suitably modified to detect other proteins.

  5. Influence of functionalization on mechanical and electrical properties of carbon nanotube-based silver composites

    Science.gov (United States)

    Pal, Hemant; Sharma, Vimal; Sharma, Manjula

    2014-05-01

    In this study, we have extended the molecular-level mixing method to fabricate multiwall carbon nanotube (CNT)-reinforced silver nanocomposites. The multiwall nanotubes used in the synthesis process were dispersed by two ways viz. covalent and non-covalent functionalization techniques. To elucidate the comparative effects of functionalization, structural, mechanical and electrical properties of nanocomposites were evaluated before and after sintering. The structural characterization revealed that the nanotubes were embedded, anchored and homogenously dispersed within the silver matrix. Hardness and Young's modulus of nanotube-reinforced nanocomposite were increased by a factor of 1-1.6 times than that of pure silver, even before and after the sintering. Covalently functionalized nanotube-based composites have shown more enhanced mechanical properties. The CNT reinforcement also improved the electrical conductivity of low-conducting nanosilver matrix before sintering. Non-covalently functionalized nanotube-based nanosilver composites showed more increased electrical conductivity before sintering. But a negative reinforcement effect was observed in high-conducting bulk silver matrix after the sintering. Thus, covalent functionalization might be appropriate for mechanical improvement in low-strength materials. However, non-covalent functionalization is suitable for electrical enhancement in low-conducting nanomaterials.

  6. Modelling the nonlinear behaviour of double walled carbon nanotube based resonator with curvature factors

    Science.gov (United States)

    Patel, Ajay M.; Joshi, Anand Y.

    2016-10-01

    This paper deals with the nonlinear vibration analysis of a double walled carbon nanotube based mass sensor with curvature factor or waviness, which is doubly clamped at a source and a drain. Nonlinear vibrational behaviour of a double-walled carbon nanotube excited harmonically near its primary resonance is considered. The double walled carbon nanotube is harmonically excited by the addition of an excitation force. The modelling involves stretching of the mid plane and damping as per phenomenon. The equation of motion involves four nonlinear terms for inner and outer tubes of DWCNT due to the curved geometry and the stretching of the central plane due to the boundary conditions. The vibrational behaviour of the double walled carbon nanotube with different surface deviations along its axis is analyzed in the context of the time response, Poincaré maps and Fast Fourier Transformation diagrams. The appearance of instability and chaos in the dynamic response is observed as the curvature factor on double walled carbon nanotube is changed. The phenomenon of Periodic doubling and intermittency are observed as the pathway to chaos. The regions of periodic, sub-harmonic and chaotic behaviour are clearly seen to be dependent on added mass and the curvature factors in the double walled carbon nanotube. Poincaré maps and frequency spectra are used to explicate and to demonstrate the miscellany of the system behaviour. With the increase in the curvature factor system excitations increases and results in an increase of the vibration amplitude with reduction in excitation frequency.

  7. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    Science.gov (United States)

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  8. A Multi-Walled Carbon Nanotube-based Biosensor for Monitoring Microcystin-LR in Sources of Drinking Water Supplies

    Science.gov (United States)

    A multi-walled carbon nanotube-based electrochemical biosensor is developed for monitoring microcystin-LR (MC-LR), a toxic cyanobacterial toxin, in sources of drinking water supplies. The biosensor electrodes are fabricated using dense, mm-long multi-walled CNT (MWCNT) arrays gro...

  9. Frequency Shift of Carbon-Nanotube-Based Mass Sensor Using Nonlocal Elasticity Theory

    Directory of Open Access Journals (Sweden)

    Lee Haw-Long

    2010-01-01

    Full Text Available Abstract The frequency equation of carbon-nanotube-based cantilever sensor with an attached mass is derived analytically using nonlocal elasticity theory. According to the equation, the relationship between the frequency shift of the sensor and the attached mass can be obtained. When the nonlocal effect is not taken into account, the variation of frequency shift with the attached mass on the sensor is compared with the previous study. According to this study, the result shows that the frequency shift of the sensor increases with increasing the attached mass. When the attached mass is small compared with that of the sensor, the nonlocal effect is obvious and increasing nonlocal parameter decreases the frequency shift of the sensor. In addition, when the location of the attached mass is closer to the free end, the frequency shift is more significant and that makes the sensor reveal more sensitive. When the attached mass is small, a high sensitivity is obtained.

  10. Charge transport in carbon nanotubes based materials: a Kubo-Greenwood computational approach

    Science.gov (United States)

    Ishii, Hiroyuki; Triozon, François; Kobayashi, Nobuhiko; Hirose, Kenji; Roche, Stephan

    2009-05-01

    In this contribution, we present a numerical study of quantum transport in carbon nanotubes based materials. After a brief presentation of the computational approach used to investigate the transport coefficient (Kubo method), the scaling properties of quantum conductance in ballistic regime as well as in the diffusive regimes are illustrated. The impact of elastic (impurities) and dynamical disorders (phonon vibrations) are analyzed separately, with the extraction of main transport length scales (mean free path and localization length), as well as the temperature dependence of the nanotube resistance. The results are found in very good agreement with both analytical results and experimental data, demonstrating the predictability efficiency of our computational strategy. To cite this article: H. Ishii et al., C. R. Physique 10 (2009).

  11. Single-wall carbon nanotube-based proton exchange membrane assembly for hydrogen fuel cells.

    Science.gov (United States)

    Girishkumar, G; Rettker, Matthew; Underhile, Robert; Binz, David; Vinodgopal, K; McGinn, Paul; Kamat, Prashant

    2005-08-30

    A membrane electrode assembly (MEA) for hydrogen fuel cells has been fabricated using single-walled carbon nanotubes (SWCNTs) support and platinum catalyst. Films of SWCNTs and commercial platinum (Pt) black were sequentially cast on a carbon fiber electrode (CFE) using a simple electrophoretic deposition procedure. Scanning electron microscopy and Raman spectroscopy showed that the nanotubes and the platinum retained their nanostructure morphology on the carbon fiber surface. Electrochemical impedance spectroscopy (EIS) revealed that the carbon nanotube-based electrodes exhibited an order of magnitude lower charge-transfer reaction resistance (R(ct)) for the hydrogen evolution reaction (HER) than did the commercial carbon black (CB)-based electrodes. The proton exchange membrane (PEM) assembly fabricated using the CFE/SWCNT/Pt electrodes was evaluated using a fuel cell testing unit operating with H(2) and O(2) as input fuels at 25 and 60 degrees C. The maximum power density obtained using CFE/SWCNT/Pt electrodes as both the anode and the cathode was approximately 20% better than that using the CFE/CB/Pt electrodes.

  12. Analysis of Tribological Behavior of Carbon Nanotube Based Industrial Mineral Gear Oil 250 cSt Viscosity

    Directory of Open Access Journals (Sweden)

    Shubrajit Bhaumik

    2014-01-01

    Full Text Available The paper investigates the exceptional antiwear and extreme pressure properties of multiwalled carbon nanotube based mineral oil. Different samples of oil containing varying proportions of MWNT (MWNT and graphite were prepared. The samples were tested for their antiwear and load bearing capacity according to ASTM G99 and ASTM D-2783 standards. After pass load test in four ball tester the rubbed surfaces were investigated with Scanning Electron Microscope (SEM images. The wear test results show a decrease wear by 70–75% in case of multiwalled nanotube based mineral oil as compared with pure mineral oil. Furthermore, it has been observed that the load bearing capacity in case of multiwalled carbon nanotube based mineral oil increases by 20% as compared to pure mineral oil. A comparison in the antiwear and load bearing capacity properties of graphite and nanotube based mineral oil was studied which showed the inefficiency of graphite based lubricant over MWNT based oil. Thus, the finding would be helpful in developing new nanoparticle based lubricants.

  13. Development of Carbon Nanotube-Based Sensor to Monitor Crack Growth in Cracked Aluminum Structures Underneath Composite Patching

    Science.gov (United States)

    2014-06-01

    carbon nanotube/epoxy composites,” Carbon, vol. 44, no. 14, pp. 3022–3029, Nov. 2006. [15] I. D. Rosca and S. V. Hoa , “Highly conductive...nanotube- based sensor- A review,” IEEE Sensors Journal, vol. 7, no. 1-2, pp. 266–284, Jan.–Feb., 2007. [23] M. Nofar, S. V. Hoa and M. D. Pugh

  14. Rectifying Properties of a Nitrogen/Boron-Doped Capped-Carbon-Nanotube-Based Molecular Junction

    Institute of Scientific and Technical Information of China (English)

    ZHAO Peng; LIU De-Sheng; ZHANG Ying; WANG Pei-Ji; ZHANG Zhong

    2011-01-01

    @@ Based on the non-equilibrium Green's function method and first-principles density functional theory calculations, we investigate the electronic transport properties of a nitrogen/boron-doped capped-single-walled carbonnanotube-based molecular junction.Obvious rectifying behavior is observed and it is strongly dependent on the doping site.The best rectifying performance can be carried out when the nitrogen/boron atom dopes at a carbon site in the second layer.Moreover, the rectifying performance can be further improved by adjusting the distance between the Cso nanotube caps.%Based on the non-equilibrium Green's function method and first-principles density functional theory calculations, we investigate the electronic transport properties of a nitrogen/boron-doped capped-single-walled carbon-nanotube-based molecular junction. Obvious rectifying behavior is observed and it is strongly dependent on the doping site. The best rectifying performance can be carried out when the nitrogen/boron atom dopes at a carbon site in the second layer. Moreover, the rectifying performance can be further improved by adjusting the distance between the C60 nanotube caps.

  15. Controlling the Cross-Sensitivity of Carbon Nanotube-Based Gas Sensors to Water Using Zeolites.

    Science.gov (United States)

    Evans, Gwyn P; Buckley, David J; Adedigba, Abdul-Lateef; Sankar, Gopinathan; Skipper, Neal T; Parkin, Ivan P

    2016-10-05

    Carbon nanotube-based gas sensors can be used to detect harmful environmental pollutants such as NO2 at room temperature. Although they show promise as low-powered, sensitive, and affordable monitoring devices, cross-sensitivity of functionalized carbon nanotubes to water vapor often obscures the detection of target molecules. This is a barrier to adoption for monitoring of airborne pollutants because of the varying humidity levels found in real world environments. Zeolites, also known as molecular sieves because of their selective adsorption properties, are used in this work to control the cross-sensitivity of single-walled carbon nanotube (SWCNT)-based sensors to water vapor. Zeolites incorporated into the sensing layer are found to reduce interference effects that would otherwise obscure the identification of NO2 gas, permitting repeatable detection over a range of relative humidities. This significant improvement is found to depend on the arrangement of the SWCNT-zeolite layers in the sensing device, as well as the hydrophilicity of the chosen zeolite.

  16. Processing and Characterization of a Novel Distributed Strain Sensor Using Carbon Nanotube-Based Nonwoven Composites

    Directory of Open Access Journals (Sweden)

    Hongbo Dai

    2015-07-01

    Full Text Available This paper describes the development of an innovative carbon nanotube-based non-woven composite sensor that can be tailored for strain sensing properties and potentially offers a reliable and cost-effective sensing option for structural health monitoring (SHM. This novel strain sensor is fabricated using a readily scalable process of coating Carbon nanotubes (CNT onto a nonwoven carrier fabric to form an electrically-isotropic conductive network. Epoxy is then infused into the CNT-modified fabric to form a free-standing nanocomposite strain sensor. By measuring the changes in the electrical properties of the sensing composite the deformation can be measured in real-time. The sensors are repeatable and linear up to 0.4% strain. Highest elastic strain gage factors of 1.9 and 4.0 have been achieved in the longitudinal and transverse direction, respectively. Although the longitudinal gage factor of the newly formed nanocomposite sensor is close to some metallic foil strain gages, the proposed sensing methodology offers spatial coverage, manufacturing customizability, distributed sensing capability as well as transverse sensitivity.

  17. Analytical Calculation of Sensing Parameters on Carbon Nanotube Based Gas Sensors

    Directory of Open Access Journals (Sweden)

    Elnaz Akbari

    2014-03-01

    Full Text Available Carbon Nanotubes (CNTs are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH3 and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH3 gas detection. With respect to this conductance change, the I–V characteristic of the CNT is investigated. Finally, a comparative study shows satisfactory agreement between the proposed model and the experimental data from the mentioned research.

  18. Bridged single-walled carbon nanotube-based atomic-scale mass sensors

    Science.gov (United States)

    Ali-Akbari, H. R.; Shaat, M.; Abdelkefi, A.

    2016-08-01

    The potentials of carbon nanotubes (CNTs) as mechanical resonators for atomic-scale mass sensing are presented. To this aim, a nonlocal continuum-based model is proposed to study the dynamic behavior of bridged single-walled carbon nanotube-based mass nanosensors. The carbon nanotube (CNT) is considered as an elastic Euler-Bernoulli beam with von Kármán type geometric nonlinearity. Eringen's nonlocal elastic field theory is utilized to model the interatomic long-range interactions within the structure of the CNT. This developed model accounts for the arbitrary position of the deposited atomic-mass. The natural frequencies and associated mode shapes are determined based on an eigenvalue problem analysis. An atom of xenon (Xe) is first considered as a specific case where the results show that the natural frequencies and mode shapes of the CNT are strongly dependent on the location of the deposited Xe and the nonlocal parameter of the CNT. It is also indicated that the first vibrational mode is the most sensitive when the mass is deposited at the middle of a single-walled carbon nanotube. However, when deposited in other locations, it is demonstrated that the second or third vibrational modes may be more sensitive. To investigate the sensitivity of bridged single-walled CNTs as mass sensors, different noble gases are considered, namely Xe, argon (Ar), and helium (He). It is shown that the sensitivity of the single-walled CNT to the Ar and He gases is much lower than the Xe gas due to the significant decrease in their masses. The derived model and performed analysis are so needed for mass sensing applications and particularly when the detected mass is randomly deposited.

  19. Pronounced Hysteresis and High Charge Storage Stability of Single-Walled Carbon Nanotube-Based Field-Effect Transistors

    OpenAIRE

    Wang, S.G.; Sellin, P.

    2005-01-01

    In this letter, pronounced hysteresis loops were observed in single-walled carbon nanotube-based field-effect transistors (CNTFETs). The shift in threshold voltage was found to increase with increasing gate voltage sweep ranges. A significant enhancement in the charge storage stability over 14 days was obtained at room temperature after a two-stage hydrogen and air annealing process was applied to the CNTFETs. The passivation of interface traps by annealing in hydrogen and the removal of phys...

  20. Analysis of Tribological Behavior of Carbon Nanotube Based Industrial Mineral Gear Oil 250 cSt Viscosity

    OpenAIRE

    Shubrajit Bhaumik; Prabhu, S.; Kingsly Jeba Singh

    2014-01-01

    The paper investigates the exceptional antiwear and extreme pressure properties of multiwalled carbon nanotube based mineral oil. Different samples of oil containing varying proportions of MWNT (MWNT) and graphite were prepared. The samples were tested for their antiwear and load bearing capacity according to ASTM G99 and ASTM D-2783 standards. After pass load test in four ball tester the rubbed surfaces were investigated with Scanning Electron Microscope (SEM) images. The wear test results s...

  1. Molecular Dynamics Simulation of a Multi-Walled Carbon Nanotube Based Gear

    Science.gov (United States)

    Han, Jie; Globus, Al; Srivastava, Deepak; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We used molecular dynamics to investigate the properties of a multi-walled carbon nanotube based gear. Previous work computationally suggested that molecular gears fashioned from (14,0) single-walled carbon nanotubes operate well at 50-100 gigahertz. The gears were formed from nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. The gear in this study was based on the smallest multi-walled nanotube supported by some experimental evidence. Each gear was a (52,0) nanotube surrounding a (37,10) nanotube with approximate 20.4 and 16,8 A radii respectively. These sizes were chosen to be consistent with inter-tube spacing observed by and were slightly larger than graphite inter-layer spacings. The benzyne teeth were attached via 2+4 cycloaddition to exterior of the (52,0) tube. 2+4 bonds were used rather than the 2+2 bonds observed by Hoke since 2+4 bonds are preferred by naphthalene and quantum calculations by Jaffe suggest that 2+4 bonds are preferred on carbon nanotubes of sufficient diameter. One gear was 'powered' by forcing the atoms near the end of the outside buckytube to rotate to simulate a motor. A second gear was allowed to rotate by keeping the atoms near the end of its outside buckytube on a cylinder. The ends of both gears were constrained to stay in an approximately constant position relative to each other, simulating a casing, to insure that the gear teeth meshed. The stiff meshing aromatic gear teeth transferred angular momentum from the powered gear to the driven gear. The simulation was performed in a vacuum and with a software thermostat. Preliminary results suggest that the powered gear had trouble turning the driven gear without slip. The larger radius and greater mass of these gears relative to the (14,0) gears previously studied requires a

  2. Molecular Dynamics Simulation of a Multi-Walled Carbon Nanotube Based Gear

    Science.gov (United States)

    Han, Jie; Globus, Al; Srivastava, Deepak; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    We used molecular dynamics to investigate the properties of a multi-walled carbon nanotube based gear. Previous work computationally suggested that molecular gears fashioned from (14,0) single-walled carbon nanotubes operate well at 50-100 gigahertz. The gears were formed from nanotubes with teeth added via a benzyne reaction known to occur with C60. A modified, parallelized version of Brenner's potential was used to model interatomic forces within each molecule. A Leonard-Jones 6-12 potential was used for forces between molecules. The gear in this study was based on the smallest multi-walled nanotube supported by some experimental evidence. Each gear was a (52,0) nanotube surrounding a (37,10) nanotube with approximate 20.4 and 16,8 A radii respectively. These sizes were chosen to be consistent with inter-tube spacing observed by and were slightly larger than graphite inter-layer spacings. The benzyne teeth were attached via 2+4 cycloaddition to exterior of the (52,0) tube. 2+4 bonds were used rather than the 2+2 bonds observed by Hoke since 2+4 bonds are preferred by naphthalene and quantum calculations by Jaffe suggest that 2+4 bonds are preferred on carbon nanotubes of sufficient diameter. One gear was 'powered' by forcing the atoms near the end of the outside buckytube to rotate to simulate a motor. A second gear was allowed to rotate by keeping the atoms near the end of its outside buckytube on a cylinder. The ends of both gears were constrained to stay in an approximately constant position relative to each other, simulating a casing, to insure that the gear teeth meshed. The stiff meshing aromatic gear teeth transferred angular momentum from the powered gear to the driven gear. The simulation was performed in a vacuum and with a software thermostat. Preliminary results suggest that the powered gear had trouble turning the driven gear without slip. The larger radius and greater mass of these gears relative to the (14,0) gears previously studied requires a

  3. Electrical characterization and microwave application of polyacrylonitrile/carbon nanotube-based carbon fibers

    Science.gov (United States)

    Sano, Eiichi; Watanuki, Takehito; Ikebe, Masayuki; Fugetsu, Bunshi

    2017-09-01

    The addition of carbon nanotubes (CNTs) in polyacrylonitrile (PAN) precursor is an effective way to increase the electrical conductivity of derived carbon fibers. The electrical conductivity of 4.9 × 104 S/m for a PAN-based carbon fiber at room temperature increases to 9.4 × 104 S/m by adding 0.5 wt % CNTs. The measured conductivity for both PAN/CNT- and PAN-based carbon fibers monotonically increases as the temperature increases from 10 and 300 K. An attempt to explain the measured temperature dependences of electrical conductivities by various carrier transport models showed that a simple two-carrier model can give reasonable electron and hole mobility. A monopole antenna fabricated with PAN/CNT-based carbon fibers shows a gain of 2.3 dBi at 2.4 GHz, which is only 0.2 dB smaller than that of a reference (Cu-wire) monopole antenna. This result suggests the possibility of using PAN/CNT-based carbon fibers as antenna elements.

  4. Heat dissipation for the Intel Core i5 processor using multiwalled carbon-nanotube-based ethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Thang, Bui Hung; Trinh, Pham Van; Quang, Le Dinh; Khoi, Phan Hong; Minh, Phan Ngoc [Vietnam Academy of Science and Technology, Ho Chi Minh CIty (Viet Nam); Huong, Nguyen Thi [Hanoi University of Science, Hanoi (Viet Nam); Vietnam National University, Hanoi (Viet Nam)

    2014-08-15

    Carbon nanotubes (CNTs) are some of the most valuable materials with high thermal conductivity. The thermal conductivity of individual multiwalled carbon nanotubes (MWCNTs) grown by using chemical vapor deposition is 600 ± 100 Wm{sup -1}K{sup -1} compared with the thermal conductivity 419 Wm{sup -1}K{sup -1} of Ag. Carbon-nanotube-based liquids - a new class of nanomaterials, have shown many interesting properties and distinctive features offering potential in heat dissipation applications for electronic devices, such as computer microprocessor, high power LED, etc. In this work, a multiwalled carbon-nanotube-based liquid was made of well-dispersed hydroxyl-functional multiwalled carbon nanotubes (MWCNT-OH) in ethylene glycol (EG)/distilled water (DW) solutions by using Tween-80 surfactant and an ultrasonication method. The concentration of MWCNT-OH in EG/DW solutions ranged from 0.1 to 1.2 gram/liter. The dispersion of the MWCNT-OH-based EG/DW solutions was evaluated by using a Zeta-Sizer analyzer. The MWCNT-OH-based EG/DW solutions were used as coolants in the liquid cooling system for the Intel Core i5 processor. The thermal dissipation efficiency and the thermal response of the system were evaluated by directly measuring the temperature of the micro-processor using the Core Temp software and the temperature sensors built inside the micro-processor. The results confirmed the advantages of CNTs in thermal dissipation systems for computer processors and other high-power electronic devices.

  5. Electrical and optical properties of reduced graphene oxide and multi-walled carbon nanotubes based nanocomposites: A comparative study

    Science.gov (United States)

    Goumri, Meryem; Lucas, Bruno; Ratier, Bernard; Baitoul, Mimouna

    2016-10-01

    Graphene and multi-walled carbon nanotubes have attracted interest for a number of potential applications. One of the most actively pursued applications uses graphene and carbon nanotubes as a transparent conducting electrode in solar cells, displays or touch screens. In this work, in situ reduced graphene oxide/Poly (vinyl alcohol) and multi-walled carbon nanotubes/Sodium Dodecyl Sulfate/Poly (vinyl alcohol) composites were prepared by water dispersion and different reduction treatments. Comparative studies were conducted to explore the electrical and optical properties of nanocomposites based on graphene and multi-walled carbon nanotubes. A thermal reduction of graphene oxide was more effective, producing films with sheet resistances as low as 102-103 Ω/square with 80% transmittance for 550 nm light. The percolation threshold of the thermally reduced graphene oxide composites (0.35 vol%) was much lower than that of the chemically reduced graphene oxide composites (0.57 vol%), and than that of the carbon nanotubes composites (0.47 vol%). The Seebeck coefficient of graphene oxide films changes from about 40 μV/K to -30 μV/K after an annealing of three hours at 200 °C. The optical absorption of the nanocomposites showed a high absorbance in near UV regions and the photoluminescence enhancement was achieved at 1 wt% graphene loading, while the carbon nanotubes based composite presents a significant emission at 0.7 wt% followed with a photoluminescence quenching at higher fraction of the nanofillers 1.6 wt% TRGO and 1 wt% MWCNTs.

  6. Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.

    2016-10-04

    Disclosed here is a device comprising a porous carbon aerogel or composite thereof as an energy storage material, catalyst support, sensor or adsorbent, wherein the porous carbon aerogel comprises a network of interconnected struts comprising carbon nanotube bundles covalently crosslinked by graphitic carbon nanoparticles, wherein the carbon nanotubes account for 5 to 95 wt. % of the aerogel and the graphitic carbon nanoparticles account for 5 to 95 wt. % of the aerogel, and wherein the aerogel has an electrical conductivity of at least 10 S/m and is capable of withstanding strains of more than 10% before fracture.

  7. Carbon Nanotube-Based Adsorbents for Ultrafine Particulate and Volatile Air Contaminants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While the protective qualities of activated carbon have been enhanced by the addition of specific metal salts, activated carbon technology has changed little over...

  8. Carbon nanotube based multi electrode arrays for neuronal interfacing: progress and prospects

    OpenAIRE

    Yael eHanein; Lilach eBareket-Keren

    2013-01-01

    Carbon nanotube coatings have been demonstrated over the past several years as a promising material for neuronal interfacing applications. In particular, in the realm of neuronal implants, carbon nanotubes have major advantages owing to their unique mechanical and electrical properties. Here we review recent investigations utilizing carbon nanotubes in neuro-interfacing applications. Cell adhesion, neuronal engineering and multi electrode recordings with carbon nanotubes are described. We als...

  9. Carbon nanotube based multi electrode arrays for neuronal interfacing: progress and prospects

    Directory of Open Access Journals (Sweden)

    Yael eHanein

    2013-01-01

    Full Text Available Carbon nanotube coatings have been demonstrated over the past several years as a promising material for neuronal interfacing applications. In particular, in the realm of neuronal implants, carbon nanotubes have major advantages owing to their unique mechanical and electrical properties. Here we review recent investigations utilizing carbon nanotubes in neuro-interfacing applications. Cell adhesion, neuronal engineering and multi electrode recordings with carbon nanotubes are described. We also highlight prospective advances in this field, in particular, progress towards flexible, bio-compatible carbon nanotubes technology.

  10. Carbon nanotube based biomedical agents for heating, temperature sensoring and drug delivery

    CERN Document Server

    Klingeler, Ruediger; Buechner, Bernd

    2009-01-01

    Due to their extraordinary physical and chemical properties carbon nanotubes reveal a promising potential as biomedical agents for heating, temperature sensoring and drug delivery on the cellular level. Filling carbon nanotubes with tailored materials realises nanoscaled containers in which the active content is encapsulated by a protecting carbon shell. We describe different synthesis routes and show the structural and magnetic properties of carbon nanotubes. In particular, the filling with magnetic materials offers the potential for hyperthermia applications while the insertion of NMR active substances allows the usage as markers and sensors. The potential of carbon nanotubes for biomedical applications is highlighted by hyperthermia studies which prove their applicability for local in-situ heating. In addition we have shown that a non-invasive temperature control by virtue of a carbon-wrapped nanoscaled thermometer and filling with anti-cancer drugs is possible.

  11. Carbon Nanotube Based Electric Propulsion Thruster with Low Power Consumption Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project is to develop field emission electric propulsion (FEEP) thruster using carbon nanotubes (CNT) integrated anode. FEEP thrusters have gained...

  12. Carbon nanotube-based coatings to induce flow enhancement in hydrophilic nanopores

    DEFF Research Database (Denmark)

    Wagemann, Enrique; Walther, Jens Honore; Zambrano, Harvey

    2016-01-01

    that carbon nanotubes (CNTs) feature ultrafast waterflow rates which result in flow enhancements of 1 to 5 orders of magnitude compared to Hagen-Poiseuille predictions. In the present study, CNT-based coatings are considered to induce water flow enhancement in silica nanopores with different radius. We......-walled carbon nanotubes implemented as coating material in silica nanopores....

  13. Carbon nanotube based separation columns for high electrical field strengths in microchip electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Chen, Miaoxiang Max; Mølhave, Kristian

    2011-01-01

    Patterning carbon nanotubes into an array of pillars makes it possible to increase the electrical field strength applied across a separation column by more than one order of magnitude.......Patterning carbon nanotubes into an array of pillars makes it possible to increase the electrical field strength applied across a separation column by more than one order of magnitude....

  14. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    NARCIS (Netherlands)

    Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

  15. Nondestructive Evaluation Techniques for Development and Characterization of Carbon Nanotube Based Superstructures

    Science.gov (United States)

    Wincheski, Buzz; Kim, Jae-Woo; Sauti, Godfrey; Wainwright, Elliot; Williams, Phillip; Siochi, Emile J.

    2014-01-01

    Recently, multiple commercial vendors have developed capability for the production of large-scale quantities of high-quality carbon nanotube sheets and yarns. While the materials have found use in electrical shielding applications, development of structural systems composed of a high volume fraction of carbon nanotubes is still lacking. A recent NASA program seeks to address this by prototyping a structural nanotube composite with strength-toweight ratio exceeding current state-of-the-art carbon fiber composites. Commercially available carbon nanotube sheets, tapes, and yarns are being processed into high volume fraction carbon nanotube-polymer nanocomposites. Nondestructive evaluation techniques have been applied throughout this development effort for material characterization and process control. This paper will report on the progress of these efforts, including magnetic characterization of residual catalyst content, Raman scattering characterization of nanotube diameter, defect ratio, and nanotube strain, and polarized Raman scattering for characterization of nanotube alignment.

  16. DQ thermal buckling analysis of embedded curved carbon nanotubes based on nonlocal elasticity theory

    National Research Council Canada - National Science Library

    Setoodeh, AliReza; Derahaki, Morteza; Bavi, Navid

    2015-01-01

    Abstract To investigate the thermal buckling of curved carbon nanotubes (CCNTs) embedded in an elastic medium, nonlocal elasticity theory is employed in combination with the theory of thin curved beams...

  17. Effect of sintering on mechanical and electrical properties of carbon nanotube based silver nanocomposites

    Science.gov (United States)

    Pal, H.; Sharma, V.

    2015-03-01

    Nanocrystalline (single and multiwall) carbon nanotube reinforced silver nanocomposites are successfully synthesized by a modified molecular level mixing method. These materials are subsequently sintered up to 800 °C in inert atmosphere for 12 h. To elucidate the effect of sintering, micro-structural, mechanical and electrical properties of fabricated nanocomposites are evaluated before and after sintering. Scanning and transmission electron microscopic characterization have revealed that the carbon nanotubes are embedded, anchored and homogenously dispersed in silver matrix. Measured hardness and Young's modulus of fabricated nanocomposites are increased by 20-30 % after sintering. The carbon nanotube reinforcement has also improved electrical conductivity of low conducting nano-silver matrix before sintering. However, negative reinforcement effect is observed in high conducting bulk silver matrix after sintering. Comparatively improved mechanical and electrical properties of single wall carbon nanotube reinforced nanocomposites than multiwall nanotube reinforced nanocomposite are observed, which are correlated with high aspect ratio and larger effective contact surface area of single wall carbon nanotubes.

  18. Carbon nanotube-based sensor and method for detection of crack growth in a structure

    Science.gov (United States)

    Smits, Jan M. (Inventor); Kite, Marlen T. (Inventor); Moore, Thomas C. (Inventor); Wincheski, Russell A. (Inventor); Ingram, JoAnne L. (Inventor); Watkins, Anthony N. (Inventor); Williams, Phillip A. (Inventor)

    2007-01-01

    A sensor has a plurality of carbon nanotube (CNT)-based conductors operatively positioned on a substrate. The conductors are arranged side-by-side, such as in a substantially parallel relationship to one another. At least one pair of spaced-apart electrodes is coupled to opposing ends of the conductors. A portion of each of the conductors spanning between each pair of electrodes comprises a plurality of carbon nanotubes arranged end-to-end and substantially aligned along an axis. Because a direct correlation exists between the resistance of a carbon nanotube and its strain, changes experienced by the portion of the structure to which the sensor is coupled induce a corresponding change in the electrical properties of the conductors, thereby enabling detection of crack growth in the structure.

  19. Carbon Nanotube Based Molecular Electronics and Motors: A View from Classical and Quantum Dynamics Simulations

    Science.gov (United States)

    Srivastava, Deepak; Saini, Subhash (Technical Monitor)

    1998-01-01

    The tubular forms of fullerenes popularly known as carbon nanotubes are experimentally produced as single-, multiwall, and rope configurations. The nanotubes and nanoropes have shown to exhibit unusual mechanical and electronic properties. The single wall nanotubes exhibit both semiconducting and metallic behavior. In short undefected lengths they are the known strongest fibers which are unbreakable even when bent in half. Grown in ropes their tensile strength is approximately 100 times greater than steel at only one sixth the weight. Employing large scale classical and quantum molecular dynamics simulations we will explore the use of carbon nanotubes and carbon nanotube junctions in 2-, 3-, and 4-point molecular electronic device components, dynamic strength characterization for compressive, bending and torsional strains, and chemical functionalization for possible use in a nanoscale molecular motor. The above is an unclassified material produced for non-competitive basic research in the nanotechnology area.

  20. Sub percolation threshold carbon nanotube based polyvinylidene fluoride polymer-polymer composites

    Science.gov (United States)

    Jacob, Cedric Antony

    The study of piezoelectric materials has traditionally focused largely on homogeneous crystalline or semi-crystalline materials. This research focuses on the concept of piezoelectric composites using selective microstructural reinforcement in the piezoelectric material to improve the piezoelectric properties. This is done using a polyvinylidene fluoride (PVDF) and carbon nanotube composite as the model system. A multi-tiered engineering approach is taken to understand the material (experimental and computational analyses) and design a composite system which provides an effective platform for future research in piezoelectric improvement. A finite element analysis is used to evaluate the ability of carbon nanotubes to generate a heterogeneous electric field where local improvements in electric field produce an increase in the effective piezoelectric strength. The study finds that weight percent and aspect ratio of the carbon nanotubes are of key importance while formations of percolating networks are detrimental to performance. This motivates investigation into electrospinning into a method of producing sub percolation threshold composites with large carbon nanotube content. However, the electrospun fabrics have too low of a dielectric strength to sustain high strength electric fields. This is studied within the context of high voltage physics and a solution inspired by traditional composites manufacturing is proposed wherein the electrospun fiber mat is used as the fiber reinforcing component of a polymer-polymer composite. This composite is thoroughly analyzed to show that it allows for a high dielectric strength combined with high carbon nanotube content. It is also shown that the PVDF contains the proper crystal structure to allow for piezoelectric properties. Furthermore, the addition of carbon nanotubes greatly improves the strength and stiffness of the composite, as well as affecting the internal electric field response to an applied voltage. These qualities

  1. Multifunctional Carbon Nanotube-Based Sensors for Damage Detection and Self Healing in Structural Composites

    Science.gov (United States)

    2010-10-29

    processing of thick-section composites, an alternative approach to the traditional calendering method of carbon nanotube dispersion has been...accomplished using a high shear stress field [2]. This method of dispersion incorporates a calendering approach through which large agglomerates of nanotubes...comparison of the different microstructural configurations resulting from the calendering approach vs. the sizing approach. The electrical conductivity of

  2. Carbon nanotube-based structural health monitoring for fiber reinforced composite materials

    Science.gov (United States)

    Liu, Hao; Liu, Kan; Mardirossian, Aris; Heider, Dirk; Thostenson, Erik

    2017-04-01

    In fiber reinforced composite materials, the modes of damage accumulation, ranging from microlevel to macro-level (matrix cracks development, fiber breakage, fiber-matrix de-bonding, delamination, etc.), are complex and hard to be detected through conventional non-destructive evaluation methods. Therefore, in order to assure the outstanding structural performance and high durability of the composites, there has been an urgent need for the design and fabrication smart composites with self-damage sensing capabilities. In recent years, the macroscopic forms of carbon nanotube materials have been maturely investigated, which provides the opportunity for structural health monitoring based on the carbon nanotubes that are integrated in the inter-laminar areas of advanced fiber composites. Here in this research, advanced fiber composites embedded with laminated carbon nanotube layers are manufactured for damage detection due to the relevant spatial electrical property changes once damage occurs. The mechanical-electrical coupling response is recorded and analyzed during impact test. The design and manufacturing of integrating the carbon nanotubes intensely affect the detecting sensitivity and repeatability of the integrated multifunctional sensors. The ultimate goal of the reported work is to develop a novel structural health monitoring method with the capability of reporting information on the damage state in a real-time way.

  3. Study of Electromagnetic Wave Absorption Properties of Carbon Nanotubes-Based Composites

    Science.gov (United States)

    2012-11-29

    Publications: [1]. G. L. Zhao, Z. Ye, Z. Li, J. A. Roberts, "New carbon nanotube-epoxy composite for dampening microwave cavity resonance", IEEE Xplore ...Nanotechnology ( IEEE - NANO), 2012 12th IEEE Conference on 20-23 Aug. 2012. [2]. Z. Li, G. L. Zhao, P. Zhang, S. Guo, J. Tang, " Thermoelectric

  4. Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites

    Science.gov (United States)

    Nikolaev, Pavel; Arepalli, Sivaram; Holmes, William; Gorelik, Olga; Files, Brad; Scott, Carl; Santos, Beatrice; Mayeaux, Brian; Victor, Joe

    1999-01-01

    The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process

  5. Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites

    Science.gov (United States)

    Nikolaev, Pavel; Arepalli, Sivaram; Holmes, William; Gorelik, Olga; Files, Brad; Scott, Carl; Santos, Beatrice; Mayeaux, Brian; Victor, Joe

    1999-01-01

    The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process

  6. Self-propelled carbon nanotube based microrockets for rapid capture and isolation of circulating tumor cells

    Science.gov (United States)

    Banerjee, Shashwat S.; Jalota-Badhwar, Archana; Zope, Khushbu R.; Todkar, Kiran J.; Mascarenhas, Russel R.; Chate, Govind P.; Khutale, Ganesh V.; Bharde, Atul; Calderon, Marcelo; Khandare, Jayant J.

    2015-05-01

    Here, we report a non-invasive strategy for isolating cancer cells by autonomously propelled carbon nanotube (CNT) microrockets. H2O2-driven oxygen (O2) bubble-propelled microrockets were synthesized using CNT and Fe3O4 nanoparticles in the inner surface and covalently conjugating transferrin on the outer surface. Results show that self-propellant microrockets can specifically capture cancer cells.Here, we report a non-invasive strategy for isolating cancer cells by autonomously propelled carbon nanotube (CNT) microrockets. H2O2-driven oxygen (O2) bubble-propelled microrockets were synthesized using CNT and Fe3O4 nanoparticles in the inner surface and covalently conjugating transferrin on the outer surface. Results show that self-propellant microrockets can specifically capture cancer cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01797a

  7. Monitoring of Glucose in Beer Brewing by a Carbon Nanotubes Based Nylon Nanofibrous Biosensor

    Directory of Open Access Journals (Sweden)

    Marco Mason

    2016-01-01

    Full Text Available This work presents the design, preparation, and characterization of a novel glucose electrochemical biosensor based on the immobilization of glucose oxidase (GOX into a nylon nanofibrous membrane (NFM prepared by electrospinning and functionalized with multiwalled carbon nanotubes (CNT. A disc of such GOX/CNT/NFM membrane (40 μm in thickness was used for coating the surface of a glassy carbon electrode. The resulting biosensor was characterized by cyclic voltammetry and chronoamperometry, with ferrocene methanol as mediator. The binding of GOX around the CNT/NFM greatly enhances the electron transfer, which results in a biosensor with a current five times higher than without CNT. The potential usefulness of the proposed biosensor was demonstrated with the analysis of glucose in commercial beverages and along the monitoring of the brewing process for making beer, from the mashing to the fermentation steps.

  8. A carbon nanotubes based ATP apta-sensing platform and its application in cellular assay.

    Science.gov (United States)

    Zhang, Libing; Wei, Hui; Li, Jing; Li, Tao; Li, Dan; Li, Yunhui; Wang, Erkang

    2010-04-15

    In this paper, a sensitive and selective fluorescent aptasensor for adenosine triphosphate (ATP) detection is constructed, based on the noncovalent assembly of dye-labeled ATP aptamer and single-walled carbon nanotubes (SWNTs). In the absence of ATP, the dye tethered to the ATP aptamer is close to SWNTs, which can effectively quench fluorescence of the dye. Upon adding ATP, the fluorophore keeps away from the quencher, since ATP specifically binds to the aptamer and competes with carbon nanotubes, resulting in an increase in the fluorescence intensity. This enables ATP to be detected down to 4.5nM. To the best of our knowledge, this is the most sensitive fluorescent ATP aptasensor. In addition, prominent fluorescence signals were obtained in cellular ATP assays, thus the aptasensor could be used to detect ATP in real samples.

  9. Carbon Nanotube-based Super Nanotube: Tailorable Thermal Conductivity at Three-dimensional

    CERN Document Server

    Zhan, Haifei; Gu, Yuantong

    2015-01-01

    The advancements of nanomaterials or nanostructures have enabled the possibility of fabricating multifunctional materials that hold great promises in engineering applications. The carbon nanotube (CNT)-based nanostructure is one representative building block for such multifunctional materials. Based on a series of in silico studies, we report the tailorability of the thermal conductivity of a three-dimensional CNT-based nanostructure, i.e., the single wall CNT (SWNT)-based super nanotube (ST). It is shown that the thermal conductivity of STs varies with different connecting carbon rings, and the ST with longer constituent SWNTs and larger diameter yield to a smaller thermal conductivity. Further results reveal that the inverse of the ST thermal conductivity exhibits a good linear relationship with the inverse of its length. Particularly, it is found that the thermal conductivity exhibits an approximately proportional relationship with the inverse of the temperature, but appears insensitive to the axial strain...

  10. Self-propelled carbon nanotube based microrockets for rapid capture and isolation of circulating tumor cells.

    Science.gov (United States)

    Banerjee, Shashwat S; Jalota-Badhwar, Archana; Zope, Khushbu R; Todkar, Kiran J; Mascarenhas, Russel R; Chate, Govind P; Khutale, Ganesh V; Bharde, Atul; Calderon, Marcelo; Khandare, Jayant J

    2015-05-21

    Here, we report a non-invasive strategy for isolating cancer cells by autonomously propelled carbon nanotube (CNT) microrockets. H2O2-driven oxygen (O2) bubble-propelled microrockets were synthesized using CNT and Fe3O4 nanoparticles in the inner surface and covalently conjugating transferrin on the outer surface. Results show that self-propellant microrockets can specifically capture cancer cells.

  11. Fabrication and Electrochemical Properties of Carbon Nanotube-based Composite Electrodes for Electrochemical Capacitor Applications

    Institute of Scientific and Technical Information of China (English)

    Kwang; Bum; Kim

    2007-01-01

    1 Results Electrochemical capacitors (ECs) are expected to be used in hybrid electric vehicles in combination with batteries or fuel cells because of their higher power density than batteries. ECs using electrical double layer capacitance of carbon based materials and pseudocapacitance of transition metal oxides are called electrochemical double layer capacitors (EDLC) and supercapacitors (or pseudocapacitor), respectively. Transition metal oxides are considered the best candidates for high energy dens...

  12. Variational principles for transversely vibrating multiwalled carbon nanotubes based on nonlocal Euler-Bernoulli beam model.

    Science.gov (United States)

    Adali, Sarp

    2009-05-01

    Variational principles are derived for multiwalled carbon nanotubes undergoing vibrations. Derivations are based on the continuum modeling with the Euler-Bernoulli beam representing the nanotubes and small scale effects taken into account via the nonlocal elastic theory. Hamilton's principle for multiwalled nanotubes is given and Rayleigh's quotient for the frequencies is derived for nanotubes undergoing free vibrations. Natural and geometric boundary conditions are derived which lead to a set of coupled boundary conditions due to nonlocal effects.

  13. Development of a Polymer-carbon Nanotubes based Economic Solar Collector

    OpenAIRE

    Kim, S. I.; Kissick, John; Spence, Stephen; Boyle, Christine

    2014-01-01

    A low cost solar collector was developed by using polymeric components as opposed to metal and glass components of traditional solar collectors. In order to utilize polymers for the absorber of the solar collector, Carbon Nanotubes (CNT) has been added as a filler to improve the thermal conductivity and the solar absorptivity of polymers. The solar collector was designed as a multi-layer construction with considering the economic manufacturing. Through the mathematical heat transfer analysis,...

  14. Vibration signature analysis of single walled carbon nanotube based nanomechanical sensors

    Science.gov (United States)

    Joshi, Anand Y.; Harsha, S. P.; Sharma, Satish C.

    2010-06-01

    In the present paper, the simulation of the mechanical responses of individual carbon nanotubes treated as thin shells with thickness has been done using FEM. The resonant frequencies of the fixed free and the bridged SWCNT have been investigated. This analysis explores the resonant frequency shift of SWCNTs caused by the changes in the size of CNT in terms of length as well as the masses. The results showed the sensitivity of the single walled carbon nanotubes to different masses and different lengths. The results indicate that the mass sensitivity of carbon nanotube nanobalances can reach 10 -21 g and the mass sensitivity increases when smaller size nanotube resonators are used in mass sensors. The vibration signature exhibits super-harmonic and sub-harmonic response with different level of mass. In order to explore the suitability of the SWCNT as a mass detector device, the simulation results of the resonant frequency of fixed free SWCNT are compared to the published experimental data. It is shown that the FEM simulation results are in good agreement with the experimental data and hence the current modelling approach is suitable as a coupled-field design tool for the development of SWCNT-based NEMS applications.

  15. Vibration Analysis of Randomly Oriented Carbon Nanotube Based on FGM Beam Using Timoshenko Theory

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rashidifar

    2015-02-01

    Full Text Available The carbon nanotube (CNT reinforced functionally graded materials (FGM are expected to be the new generation materials having wide range of unexplored potential applications in various technological areas such as aerospace and structural and chemical industry. The present work deals with the finite element modeling and free vibration analysis of CNT based functionally graded beam using three-dimensional Timoshenko beam theory. It has been assumed that the material properties of CNT based FG beam vary only along the thickness and these properties are evaluated by rule of mixture. The extended Hamilton principle has been applied to find out the governing equations of CNT based FG beam. Finite element method is used to solve governing equation with the exact shape functions. Initial analysis deals with CNTs assumed to be oriented along the length direction only. But practically it is not possible. So, further work deals with the free vibration analysis of functionally graded nanocomposite beams reinforced by randomly oriented straight single walled carbon nanotubes (SWCNTs. The Eshelby-Mori-Tanaka approach based on an equivalent fiber is used to investigate the material properties of the beam. Results are presented in tabular and graphical forms to show the effects of carbon nanotube orientations, slenderness ratios, and boundary conditions on the dynamic behavior of the beam.

  16. Potentiometric online detection of aromatic hydrocarbons in aqueous phase using carbon nanotube-based sensors.

    Science.gov (United States)

    Washe, Alemayehu P; Macho, Santiago; Crespo, Gastón A; Rius, F Xavier

    2010-10-01

    Surfaces made of entangled networks of single-walled carbon nanotubes (SWCNTs) display a strong adsorption affinity for aromatic hydrocarbons. Adsorption of these compounds onto the walls of SWCNTs changes the electrical characteristics of the SWCNT-solution interface. Using these features, we have developed a potentiometric sensor to detect neutral aromatic species. Specifically, we can detect online aromatic hydrocarbons in industrial coolant water. Our chromatographic results confirm the adsorption of toluene onto the walls of carbon nanotubes, and our impedance spectroscopy data show the change in the double layer capacitance of the carbon nanotube-solution interface upon addition of toluene, thus confirming the proposed sensing mechanism. The sensor showed a toluene concentration dependent EMF response that follows the shape of an adsorption isotherm and displayed an immediate response to the presence of toluene with a detection limit of 2.1 ppm. The sensor does not respond to other nonaromatic hydrocarbons that may coexist with aromatic hydrocarbons in water. It shows a qualitative sensitivity and selectivity of 100% and 83%, respectively, which confirms its ability to detect aromatic hydrocarbons in aqueous solutions. The sensor showed an excellent ability to immediately detect the presence of toluene in actual coolant water. Its operational characteristics, including its fast response, low cost, portability, and easy use in online industrial applications, improve those of current chromatographic or spectroscopic techniques.

  17. Carbon-nanotube-based single electron memories processed by double self-assembly

    Science.gov (United States)

    Bouchiat, Vincent; Marty, Laetitia; Naud, Cecile; Bonhomme, Aurore; Andre, Emmanuel; Iaia, Antonio; Richard, Emmanuelle

    2005-03-01

    We demonstrate wafer-scale integration and operation of single electron memories based on carbon nanotube field effect transistors (CNFETs). Our method involves a two step double self assembly process. The first step consists of a Hot-Filament CVD growth and in situ electrical connection of single walled carbon nanotubes on a predefined submicron catalytic template acting as contact electrodes. We obtain a overall integration yield of semiconducting carbon nanotubes exhibiting field effect that can exceed 50% for 9000 devices on a 2 inches wafer. The second step is a wet step which consists of local functionalization and controlled attachment of a colloidal gold bead of radius 15nm on the nanotube. The sample is then coated with parylene dielectric followed by deposition of a top gate electrode aligned with respect to the nanotubes. The bead acts as a storage node for the memory while the CNFETs operated in the subthreshold regime behave as electrometers with exponential amplification. Operation of devices with retention of single charge quantum is successfully demonstrated at liquid helium temperature. Depending on the nanotube-dot coupling, the transfer of a single electron into the gold dot can lead up to one order of magnitude increase of the CNFET channel current.

  18. Carbon nanotubes-based chemiresistive immunosensor for small molecules: Detection of nitroaromatic explosives

    Science.gov (United States)

    Park, Miso; Cella, Lakshmi N; Chen, Wilfred; Myung, Nosang V.

    2010-01-01

    In recent years, there has been a growing focus on use of one-dimensional (1-D) nanostructures, such as carbon nanotubes and nanowires, as transducer elements for label-free chemiresistive/field-effect transistor biosensors as they provide label-free and high sensitivity detection. While research to-date has elucidated the power of carbon nanotubes- and other 1-D nanostructure- based field effect transistors immunosensors for large charged macromolecules such as proteins and viruses, their application to small uncharged or charged molecules has not been demonstrated. In this paper we report a single-walled carbon nanotubes (SWNTs)-based chemiresistive immunosensor for label-free, rapid, sensitive and selective detection of 2,4,6-trinitrotoluene (TNT), a small molecule. The newly developed immunosensor employed a displacement mode/format in which SWNTs network forming conduction channel of the sensor was first modified with trinitrophenyl (TNP), an analog of TNT, and then ligated with the anti-TNP single chain antibody. Upon exposure to TNT or its derivatives the bound antibodies were displaced producing a large change, several folds higher than the noise, in the resistance/conductance of SWNTs giving excellent limit of detection, sensitivity and selectivity. The sensor detected between 0.5 ppb and 5000 ppb TNT with good selectivity to other nitroaromatic explosives and demonstrated good accuracy for monitoring TNT in untreated environmental water matrix. We believe this new displacement format can be easily generalized to other one-dimensional nanostructure-based chemiresistive immuno/affinity-sensors for detecting small and/or uncharged molecules of interest in environmental monitoring and health care. PMID:20688506

  19. Carbon Nanotube-Based Electrochemical Sensor for the Determination of Anthraquinone Hair Dyes in Wastewaters

    Directory of Open Access Journals (Sweden)

    Ricardo de Oliveira

    2015-03-01

    Full Text Available The present work describes the development of a voltammetric sensor for the selective determination of Acid Green 25 (AG25 hair dye, widely used in commercial temporary hair dyes. The method is based on a glassy carbon electrode modified with multiwalled carbon nanotubes activated in the presence of sulfuric acid, where the anthraquinone group present as a chromophore in the dye molecule is reduced at −0.44 V vs. Ag/AgCl in a reversible process involving two electrons in Britton-Robinson (B-R buffer solution at pH 4.0. Analytical curves were obtained using square wave voltammetry in the range from 1.0 × 10−7 to 7.0 × 10−6 mol·L−1, achieving a detection limit of 2.7 × 10−9 mol·L−1. The voltammograms recorded for the Acid Black 1 (AB1 dye showed that the azo groups of the dye were reduced on the carbon nanotube-modified electrode (CNTME, presenting a pair of redox peaks at −0.27 V and −0.24 V in the reverse scan. Under these experimental conditions, both dyes could be detected in the water sample, since the AG25 dye is reduced at −0.47 V. The presence of other hair dyes bearing other chromophore groups, such as Acid Black 1, Acid Red 33 and basic blue 99, did not interfere with the method, which showed an average recovery of 96.7 ± 3.5% (n = 5 for AG25 dye determination in the presence of all of these dyes. The method was successfully applied to tap water and wastewater samples collected from a water treatment plant.

  20. Carbon Nanotubes-Based Potentiometric Bio-Sensors for Determination of Urea

    Directory of Open Access Journals (Sweden)

    Ewa Jaworska

    2015-07-01

    Full Text Available The possibility of using disposable plastic-carbon potentiometric sensors as enzyme biosensors was examined. Urease enzyme was immobilized on poly(vinyl chloride based H+- or NH4+-selective membranes using cellulose acetate. This approach has resulted in a potentiometric response on changing the pH of the solution or NH4+ ion content due to an enzymatic reaction that occurs between urease and urea. Both types of potentiometric biosensors for urea were characterized by good analytical parameters as high sensitivity and fast response time.

  1. Gas sensing properties of branched carbon nanotube-based structures using a novel low voltage emission.

    Science.gov (United States)

    Darbari, S; Azimi, S; Abdi, Y; Mohajerzadeh, S

    2012-11-01

    Branched carbon nanostructures have been successfully grown on interdigital comb-like structures for a gas sensing application. Field emission scanning electron microscopy has been utilized to investigate the morphology and structure of the grown nanostructures at different stages of growth process. Tunneling current of the fabricated sensor has been measured when a monotonically increasing voltage is applied between the electrodes. The effect of exposure to three different gases on the measured current has been studied. A data processing on the measured current voltage characteristics results in the evolution of various peaks at distinct voltages which depends on the type of the gas.

  2. Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-03-24

    Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

  3. An approach to a multi walled carbon nanotube based mass sensor

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Davis, Zachary James; Madsen, Dorte Nørgaard;

    2004-01-01

    We propose an approach to a nanoscale mass sensor based on a gold electrode structure, on which a multi-walled carbon nanotube (MWCNT) bridge can be placed and soldered. The structure is comprised of three electrodes with a width of 2 or 4 mum. Two outer electrodes with a length of 10 or 15 mum...... the bridging nanotube. The free standing MWCNTs were fabricated by chemical vapour deposition of Fe(H) phthalocyanine. A nanomanipulator with an x - y - z translation stage was used for placing the MWCNTs across the source-drain electrodes. The nanotubes were soldered onto the substrate by electron beam...

  4. Measurement of Contractile Activity in Small Animal's Digestive Organ by Carbon Nanotube-Based Force Transducer

    Science.gov (United States)

    Hirata, Takamichi; Takeda, Naoki; Tsutsui, Chihiro; Koike, Kanako; Shimatani, Yuichi; Sakai, Takafumi; Akiya, Masahiro; Taguchi, Akira

    2011-03-01

    A carbon nanotube (CNT)-based force transducer designed to be embedded in the body of a live animal was fabricated and implanted into the stomach of a rat omit to measure contractile movement. The transducer comprised dispersed poly(ethylene glycol)-grafted multiwalled CNTs applied to a comb-like Au-electrode formed on a poly(dimethylsiloxane) sheet. The implanted rat was injected with acetylcholine to induce muscular contractions and changes in the resistance of the transducer were measured. Such changes arise owing to strain in the CNT network upon distortion. The measured resistance change was found to be proportional to the concentration of injected acetylcholine.

  5. Building a multi-walled carbon nanotube-based mass sensor with the atomic force microscope

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Kuhle, A.; Marie, Rodolphe Charly Willy;

    2005-01-01

    We report an approach for building a mass sensor based on multi-walled carbon nanotubes (MWCNT). We propose a method with a great potential for the positioning of MWCNTs based on self-assembly onto patterned hydrophilic areas. For the experiments ultra flat mica substrates covered with gold...... are used. The gold substrate is first covered with hydrophobic thiol molecules: octadecanthiol. The octadecanthiol molecules are then selectively removed from small areas by nanoshaving the gold substrate with the tip of an atomic force microscope (AFM) operating in contact mode. Hydrophilic thiols (2...

  6. Development of novel graphene and carbon nanotubes based multifunctional polymer matrix composites

    Science.gov (United States)

    Leung, S. N.; Khan, M. O.; Naguib, H. E.

    2014-05-01

    This paper investigates strategies to alter the nano-and-microstructures of carbon-based filler-reinforced polymer matrix composites (PMCs). The matrix materials being studied in this work include polyphenylene sulfide (PPS) and liquid crystal polymer (LCP). A set of experiments were performed to investigate various strategies (i) to fabricate a morphological structure within the polymer matrix; (ii) to develop a thermally and electrically conductive network of nano-scaled fillers; and (iii) to produce a thermally conductive but electrically insulative network of hybrid fillers of nano-and-micro scales. The PMCs' structure-to-property relationships, including electrical and thermal properties, were revealed. In particular, the composites' effective thermal conductivities could be increased by as much as 10-folded over the neat polymers. By structuring the embedded electrically conductive pathways in the PMCs, their electrical conductivities could be tailored to levels that ranged from those of electrical insulators to those of semi-conductors. These multifunctional carbon-based filler-reinforced PMCs are envisioned to be potential solutions of various engineering problems. For example, light-weight thermally conductive PMCs with tailored electrical conductivities can serve as a new family of materials for electronic packaging or heat management applications.

  7. Growth of half-meter long carbon nanotubes based on Schulz-Flory distribution.

    Science.gov (United States)

    Zhang, Rufan; Zhang, Yingying; Zhang, Qiang; Xie, Huanhuan; Qian, Weizhong; Wei, Fei

    2013-07-23

    The Schulz-Flory distribution is a mathematical function that describes the relative ratios of polymers of different length after a polymerization process, based on their relative probabilities of occurrence. Carbon nanotubes (CNTs) are big carbon molecules which have a very high length-to-diameter ratio, somewhat similar to polymer molecules. Large amounts of ultralong CNTs have not been obtained although they are highly desired. Here, we report that the Schulz-Flory distribution can be applied to describe the relative ratios of CNTs of different lengths produced with a floating chemical vapor deposition process, based on catalyst activity/deactivation probability. With the optimized processing parameters, we successfully synthesized 550-mm-long CNTs, for which the catalyst deactivation probability of a single growth step was ultralow. Our finding bridges the Schulz-Flory distribution and the synthesis of one-dimensional nanomaterials for the first time, and sheds new light on the rational design of process toward controlled production of nanotubes/nanowires.

  8. Characteristics of permeability in carbonate areas of Korea

    Science.gov (United States)

    Park, Y.; Lee, J.; Lim, H.; Keehm, Y.

    2010-12-01

    Permeability (hydraulic conductivity) in carbonate areas is affected by various factors such as fracture, pore and degree of weathering and diagenesis. Also, caves developed in carbonate area are main factors. This study was performed to understand factors controlling the permeability in carbonate areas in Korea. In order to conduct this study, the permeability and well logging data (n=30) were collected from many literatures and rock samples were collected around wells. Vertical profile of the carbonate areas can be classified into soil, weathered carbonate and fresh carbonate zone. They show a different range at each region. Most of the rock samples were hardly weathered. The permeability showed wide ranges (0.009 to 1.1 m/day). The average value of the permeability was 0.159 m/day. However, 80% (n=24) of total data had the permeability valves lower than 0.1 m/day. The permeability values were distinguished according to degree of development of fractures. The permeability showed low values (approximately 0.5 m/day) in highly fractured carbonate. These results mean that fractures are dominant factors controlling the permeability in carbonate areas of Korea than others. This work was supported by Energy Resource R&D program (2009T100200058) under the Ministry of Knowledge Economy, Republic of Korea.

  9. Carbon nanotube-based electrochemical biosensing platforms: fundamentals, applications, and future possibilities.

    Science.gov (United States)

    Luong, John H T; Male, Keith B; Hrapovic, Sabahudin

    2007-01-01

    Biosensors can be considered as a most plausible and exciting application area for nanobiotechnology. The recent bloom of nanofabrication technology and biofunctionalization methods of carbon nanotubes (CNTs) has stimulated significant research interest to develop CNT-based biosensors for monitoring biorecognition events and biocatalytic processes. The unique properties of CNTs, rolled-up sheets of carbon atoms with a diameter less than 1 nm, offer excellent prospects for interfacing biological recognition events with electronic signal transduction. CNT-based biosensors could be developed to sense only a few or even a single molecule of a chemical or biological agent. Both hydrogen peroxide and NADH, two by-products of over 300 oxidoreductases, are efficiently oxidized by CNT-modified electrodes at significantly lower potentials with minimal surface fouling. This appealing feature enables the development of useful biosensors for diversified applications. Aligned CNT "forests" can act as molecular wires to allow efficient electron transfer between the detecting electrode and the redox centers of enzymes to fabricate reagentless biosensors. Electrochemical sensing for DNA can greatly benefit from the use of CNT based platforms since guanine, one of the four bases, can be detected with significantly enhanced sensitivity. CNTs fluoresce, or emit light after absorbing light, in the near infrared region and retain their ability to fluoresce over time. This feature will allow CNT-based sensors to transmit information from inside the body. The combination of micro/nanofabrication and chemical functionalization, particularly nanoelectrode assembly interfaced with biomolecules, is expected to pave the way to fabricate improved biosensors for proteins, chemicals, and pathogens. However, several technical challenges need to be overcome to tightly integrate CNT-based platforms with sampling, fluidic handling, separation, and other detection principles. The biosensing platform

  10. Carbon Nanotube-Based Nanomechanical Sensor: Theoretical Analysis of Mechanical and Vibrational Properties

    Directory of Open Access Journals (Sweden)

    Toshiaki Natsuki

    2017-08-01

    Full Text Available This paper reviews the recent research of carbon nanotubes (CNTs used as nanomechanical sensing elements based mainly on theoretical models. CNTs have demonstrated considerable potential as nanomechanical mass sensor and atomic force microscope (AFM tips. The mechanical and vibrational characteristics of CNTs are introduced to the readers. The effects of main parameters of CNTs, such as dimensions, layer number, and boundary conditions on the performance characteristics are investigated and discussed. It is hoped that this review provides knowledge on the application of CNTs as nanomechanical sensors and computational methods for predicting their properties. Their theoretical studies based on the mechanical properties such as buckling strength and vibration frequency would give a useful reference for designing CNTs as nanomechanical mass sensor and AFM probes.

  11. CFD Analysis for Optimum Thermal Design of Carbon Nanotube Based Micro-Channel Heatsink

    Directory of Open Access Journals (Sweden)

    M. Mahbub

    2011-10-01

    Full Text Available Carbon nanotube (CNT is considered as an ideal material for thermal management in electronic packaging because of its extraordinary high thermal conductivity. Fabricated onto a silicon substrate to form micro-channels, the CNT based cooling fins show high heat dissipation efficiency. A series of 2D and 3D CFD simulations have been carried out for CNT based micro-channel cooling architectures based on one and two dimensional fin array in this paper using COMSOL 4.0a software. Micro-channels are generally regarded as an effective method for the heat transfer in electronic products. The influence of various fluids, micro-fin structures, fluid velocity and heating powers on cooling effects have been simulated and compared in this study. Steady-state thermal stress analyses for the forced convection heat transfer are also performed to determine maximum allowable stress and deflections for the different types of cooling assembly.

  12. Using of Multiwall Carbon Nanotube Based Nanofluid in the Heat Pipe to Get Better Thermal Performance

    Directory of Open Access Journals (Sweden)

    Y. Bakhshan

    2014-09-01

    Full Text Available Thermal performance of a cylindrical heat pipe is investigated numerically. Three different types of water based nanofluids, namely, Al2O3 + Water, Diamond + Water, and Multi-Wall Carbon Nano tube (MWCNT + Water, have been used. The influence of using the simple nanofluids and MWCNT nanofluid on the heat pipe characteristics such as liquid velocity, pressure profile, temperature profile, thermal resistance, and heat transfer coefficient of heat pipe has been studied. A new correlation developed by Bakhshan and Saljooghi (2014 for viscosity of nanofluids has been implemented. The results show, a good agreement with the available analytical and experimental data. Also the results show, that the MWCNT based nanofluid has lower thermal resistance, higher heat transfer coefficient, and lower temperature difference between evaporator and condenser sections, so it has good thermal specifications as a working fluid for use in heat pipes. The prepared code has capability for parametric studies also.

  13. Carbon-Nanotube-Based Electrochemical Double-Layer Capacitor Technologies for Spaceflight Applications

    Science.gov (United States)

    Arepalli, S.; Fireman, H.; Huffman, C.; Maloney, P.; Nikolaev, P.; Yowell, L.; Kim, K.; Kohl, P. A.; Higgins, C. D.; Turano, S. P.

    2005-01-01

    Electrochemical double-layer capacitors, or supercapacitors, have tremendous potential as high-power energy sources for use in low-weight hybrid systems for space exploration. Electrodes based on single-wall carbon nanotubes (SWCNTs) offer exceptional power and energy performance due to the high surface area, high conductivity, and the ability to functionalize the SWCNTs to optimize capacitor properties. This paper will report on the preparation of electrochemical capacitors incorporating SWCNT electrodes and their performance compared with existing commercial technology. Preliminary results indicate that substantial increases in power and energy density are possible. The effects of nanotube growth and processing methods on electrochemical capacitor performance is also presented. The compatibility of different SWCNTs and electrolytes was studied by varying the type of electrolyte ions that accumulate on the high-surface-area electrodes.

  14. Novel Carbon Nanotube-Based Nanostructures for High-Temperature Gas Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhi Chen; Kozo Saito

    2008-08-31

    The primary objective of this research is to examine the feasibility of using vertically aligned multi-wall carbon nanotubes (MWCNTs) as a high temperature sensor material for fossil energy systems where reducing atmospheres are present. In the initial period of research, we fabricated capacitive sensors for hydrogen sensing using vertically aligned MWCNTs. We found that CNT itself is not sensitive to hydrogen. Moreover, with the help of Pd electrodes, hydrogen sensors based on CNTs are very sensitive and fast responsive. However, the Pd-based sensors can not withstand high temperature (T<200 C). In the last year, we successfully fabricated a hydrogen sensor based on an ultra-thin nanoporous titanium oxide (TiO{sub 2}) film supported by an AAO substrate, which can operate at 500 C with hydrogen concentrations in a range from 50 to 500 ppm.

  15. Electrical and mechanical characterisation of single wall carbon nanotubes based composites for tissue engineering applications.

    Science.gov (United States)

    Whulanza, Yudan; Battini, Elena; Vannozzi, Lorenzo; Vomero, Maria; Ahluwalia, Arti; Vozzi, Giovanni

    2013-01-01

    This paper presents the realisation of conductive matrices for application to tissue engineering research. We used poly(L-lactide (PLLA)), poly(epsilon-caprolactone) (PCL), and poly(lactide-co-glycolide) (PLGA) as polymer matrix, because they are biocompatible and biodegradable. The conductive property was integrated to them by adding single wall carbon nanotubes (SWNTs) into the polymer matrix. Several SWNTs concentrations were introduced aiming to understand how they influence and modulate mechanical properties, impedance features and electric percolation threshold of polymer matrix. It was observed that a concentration of 0.3% was able to transform insulating matrix into conductive one. Furthermore, a conductive model of the SWNT/polymer was developed by applying power law of percolation threshold.

  16. Bioinspired Multifunctional Superhydrophobic Surfaces with Carbon-Nanotube-Based Conducting Pastes by Facile and Scalable Printing.

    Science.gov (United States)

    Han, Joong Tark; Kim, Byung Kuk; Woo, Jong Seok; Jang, Jeong In; Cho, Joon Young; Jeong, Hee Jin; Jeong, Seung Yol; Seo, Seon Hee; Lee, Geon-Woong

    2017-03-01

    Directly printed superhydrophobic surfaces containing conducting nanomaterials can be used for a wide range of applications in terms of nonwetting, anisotropic wetting, and electrical conductivity. Here, we demonstrated that direct-printable and flexible superhydrophobic surfaces were fabricated on flexible substrates via with an ultrafacile and scalable screen printing with carbon nanotube (CNT)-based conducting pastes. A polydimethylsiloxane (PDMS)-polyethylene glycol (PEG) copolymer was used as an additive for conducting pastes to realize the printability of the conducting paste as well as the hydrophobicity of the printed surface. The screen-printed conducting surfaces showed a high water contact angle (WCA) (>150°) and low contact angle hysteresis (WCA superhydrophobic surfaces also showed sticky superhydrophobic characteristics and were used to transport water droplets. Moreover, fabricated films on metal meshes were used for an oil/water separation filter, and liquid evaporation behavior was investigated on the superhydrophobic and conductive thin-film heaters by applying direct current voltage to the film.

  17. Intrinsic memory function of carbon nanotube-based ferroelectric field-effect transistor.

    Science.gov (United States)

    Fu, Wangyang; Xu, Zhi; Bai, Xuedong; Gu, Changzhi; Wang, Enge

    2009-03-01

    We demonstrate the intrinsic memory function of ferroelectric field-effect transistors (FeFETs) based on an integration of individual single-walled carbon nanotubes (SWCNTs) and epitaxial ferroelectric films. In contrast to the previously reported "charge-storage" CNT-FET memories, whose operations are haunted by a lack of control over the "charge traps", the present CNT-FeFETs exhibit a well-defined memory hysteresis loop induced by the reversible remnant polarization of the ferroelectric films. Large memory windows approximately 4 V, data retention time up to 1 week, and ultralow power consumption (energy per bit) of femto-joule, are highlighted in this report. Further simulations and experimental results show that the memory device is valid under operation voltage less than 1 V due to an electric-field enhancement effect induced by the ultrathin SWCNTs.

  18. Carbon Nanotube-Based Digital Vacuum Electronics and Miniature Instrumentation for Space Exploration

    Science.gov (United States)

    Manohara, H.; Toda, R.; Lin, R. H.; Liao, A.; Mojarradi, M.

    2010-01-01

    JPL has developed high performance cold cathodes using arrays of carbon nanotube bundles that produce > 15 A/sq cm at applied fields of 5 to 8 V/micron without any beam focusing. They have exhibited robust operation in poor vacuums of 10(exp -6) to 10(exp -4) Torr- a typically achievable range inside hermetically sealed microcavities. Using these CNT cathodes JPL has developed miniature X-ray tubes capable of delivering sufficient photon flux at acceleration voltages of electronics potentially for Venus in situ missions and defense applications. These digital vacuum electronic devices are inherently high-temperature tolerant and radiation insensitive. Device design, fabrication and DC switching operation at temperatures up to 700 C are presented in this paper.

  19. Electrophoretically deposited multiwalled carbon nanotube based amperometric genosensor for E.coli detection

    Science.gov (United States)

    Bhardwaj, Hema; Solanki, Shipra; Sumana, Gajjala

    2016-04-01

    This work reports on a sensitive and selective genosensor fabrication method for Escherichia coli (E.coli) detection. The functionalized multiwalled carbon nanotubes (MWCNT) synthesized via chemical vapour deposition have been deposited electrophoretically onto indium tin oxide coated glass surface and have been utilized as matrices for the covalent immobilization of E.coli specific probe oligonucleotide that was identified from the 16s rRNA coding region of the E.coli genome. This fabricated functionalized MWCNT based platform sought to provide improved fundamental characteristics to electrode interface in terms of electro-active surface area and diffusion coefficient. Electrochemical cyclic voltammetry revealed that this genosensor exhibits a linear response to complementary DNA in the concentration range of 10-7 to 10-12 M with a detection limit of 1×10-12 M.

  20. Determination of calcium ion in sap using carbon nanotube-based ion-selective electrodes.

    Science.gov (United States)

    Hernández, Rafael; Riu, Jordi; Rius, F Xavier

    2010-08-01

    A new reduced-size solid-state electrode using carbon nanotubes as the transducing layer has been developed for the direct determination of Ca(2+) in sap, overcoming problems encountered by commercial ISEs analysing real complex samples. We show that this solid-contact ISE, which can be easily miniaturized, can be used directly in diluted real samples without any other pretreatment. The performance parameters of the new ISE include a Nernstian slope and excellent stability, good coefficients of selectivity, range of linearity (10(-5) to 10(-2.5) M) and limit of detection (10(-6.2) M), thus making it an excellent tool for determining Ca(2+) in a wide range of plant species.

  1. Carbon nanotube based X-ray sources: Applications in pre-clinical and medical imaging

    Science.gov (United States)

    Lee, Yueh Z.; Burk, Laurel; Wang, Ko-Han; Cao, Guohua; Lu, Jianping; Zhou, Otto

    2011-08-01

    Field emission offers an alternate method of electron production for Bremsstrahlung based X-ray tubes. Carbon nanotubes (CNTs) serve as very effective field emitters, allowing them to serve as electron sources for X-ray sources, with specific advantages over traditional thermionic tubes. CNT derived X-ray sources can create X-ray pulses of any duration and frequency, gate the X-ray pulse to any source and allow the placement of many sources in close proximity.We have constructed a number of micro-CT systems based on CNT X-ray sources for applications in small animal imaging, specifically focused on the imaging of the heart and lungs. This paper offers a review of the pre-clinical applications of the CNT based micro-CT that we have developed. We also discuss some of the current and potential clinical applications of the CNT X-ray sources.

  2. Fabrication of single-walled carbon-nanotube-based pressure sensors.

    Science.gov (United States)

    Stampfer, C; Helbling, T; Obergfell, D; Schöberle, B; Tripp, M K; Jungen, A; Roth, S; Bright, V M; Hierold, C

    2006-02-01

    We report on the fabrication and characterization of bulk micromachined pressure sensors based on individual single-walled carbon nanotubes (SWNTs) as the active electromechanical transducer elements. The electromechanical sensor device consists of an individual electrically connected SWNT adsorbed on top of a 100-nm-thick atomic layer deposited (ALD) circular alumina (Al(2)O(3)) membrane with a radius in the range of 50-100 microm. A white light interferometer (WLI) was used to measure the deflection of the membrane due to differential pressure, and the mechanical properties of the device were characterized by bulge testing. Finally, we performed the first electromechanical measurements on strained metallic SWNTs adhering to a membrane and found a piezoresistive gauge factor of approximately 210 for metallic SWNTs.

  3. Multi-walled carbon nanotubes based catalyst plasmon resonance light scattering analysis of tetracycline hydrochloride

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It was found that multi-walled carbon nanotubes (MWNTs) could catalyze the redox reaction between chlorauric acid (HAuCl4) and reductive drugs such as tetracycline hydrochloride (TC), producing gold nanoparticles (Au NPs). By measuring the plasmon resonance light scattering (PRLS) signals of the resulting Au NPs, tetracycline hydrochloride can be detected simply and rapidly with a linear range of 4―26 μmol/L, a correlated coefficient (r ) of 0.9955, and a limit of detection (3σ) of 6.0 nmol/L. This method has been successfully applied to the detection of tetracycline hydrochloride tablets in clinic with the recovery of 101.9% and that of fresh urine samples with the recovery of 98.3%―102.0%.

  4. Label-Free Electrical Detection Using Carbon Nanotube-Based Biosensors

    Directory of Open Access Journals (Sweden)

    Kenzo Maehashi

    2009-07-01

    Full Text Available Label-free detections of biomolecules have attracted great attention in a lot of life science fields such as genomics, clinical diagnosis and practical pharmacy. In this article, we reviewed amperometric and potentiometric biosensors based on carbon nanotubes (CNTs. In amperometric detections, CNT-modified electrodes were used as working electrodes to significantly enhance electroactive surface area. In contrast, the potentiometric biosensors were based on aptamer-modified CNT field-effect transistors (CNTFETs. Since aptamers are artificial oligonucleotides and thus are smaller than the Debye length, proteins can be detected with high sensitivity. In this review, we discussed on the technology, characteristics and developments for commercialization in label-free CNT-based biosensors.

  5. Viscoelastic wave propagation in the viscoelastic single walled carbon nanotubes based on nonlocal strain gradient theory

    Science.gov (United States)

    Tang, Yugang; Liu, Ying; Zhao, Dong

    2016-10-01

    In this paper, the viscoelastic wave propagation in an embedded viscoelastic single-walled carbon nanotube (SWCNT) is studied based on the nonlocal strain gradient theory. The characteristic equation for the viscoelastic wave in SWCNTs is derived. The emphasis is placed on the influence of the tube diameter on the viscoelastic wave dispersion. A blocking diameter is observed, above which the wave could not propagate in SWCNTs. The results show that the blocking diameter is greatly dependent on the damping coefficient, the nonlocal and the strain gradient length scale parameters, as well as the Winkler modulus of the surrounding elastic medium. These findings may provide a prospective application of SWCNTs in nanodevices and nanocomposites.

  6. Morphology and Cure Behavior of Multi-walled Carbon Nanotubes-based Thermally Conductive Adhesive

    Institute of Scientific and Technical Information of China (English)

    WANG Junxia; YAN Shilin; HE Yunban; YAN Fei; XIE Beiping

    2014-01-01

    We evaluated the cure behavior of multi-walled carbon nanotubes (MWCNTs) based thermally conductive adhesive by comprehensively thermal analysis, which presented extremely complicated variability of conversion ratioαas a function of temperature with synergistic action of positive effect and negative volume-blocking effect of MWCNTs and cross-linked network of cured polymer molecules. Due to the decomposition of MWCNTs and degradation of polymer, the mass drop is dramatically obvious over the temperature range of 330-370℃. Binary resins filled with acid-treated MWCNTs present similar reaction interval as neat epoxy and matrix resins, which is distinct from the material filled with raw MWCNTs. The alteration of the crystalline temperature and cure temperature of resins is attributed to heterogeneous nucleation of MWCNTs in matrix resins. The-COOH group of acid-treated MWCNTs reacts with epoxy groups and thus generates cross-linking, accelerates the reaction rate and reduces the cure temperature.

  7. Shear deformable deformation of carbon nanotubes based on a new analytical nonlocal Timoshenko beam nodel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianming; Yang, Yang [Department of Engineering Mechanics, Kunming University of Science and Technology, Kunming 650051, Yunnan (China)

    2015-03-10

    According to Hamilton’s principle, a new mathematical model and analytical solutions for nonlocal Timoshenko beam model (ANT) is established based on nonlocal elastic continuum theory when shear deformation and nonlocal effect are considered. The new ANT equilibrium equations and boundary conditions are derived for bending analysis of carbon nanotubes (CNTs) with simply supported, clamped and cantilever. The ANT deflection solutions demonstrate that the CNT stiffness is enhanced by the presence of nonlocal stress effects. Furthermore, the new ANT model concluded verifiable bending behaviors for a cantilever CNT with point load at the free end, which depends on the strength of nonlocal stress. Therefore, this new model will gives a better prediction for mechanical behaviors of nanostructures.

  8. Detection of airborne carbon nanotubes based on the reactivity of the embedded catalyst.

    Science.gov (United States)

    Neubauer, N; Kasper, G

    2015-01-01

    A previously described method for detecting catalyst particles in workplace air((1,2)) was applied to airborne carbon nanotubes (CNT). It infers the CNT concentration indirectly from the catalytic activity of metallic nanoparticles embedded as part of the CNT production process. Essentially, one samples airborne CNT onto a filter enclosed in a tiny chemical reactor and then initiates a gas-phase catalytic reaction on the sample. The change in concentration of one of the reactants is then determined by an IR sensor as measure of activity. The method requires a one-point calibration with a CNT sample of known mass. The suitability of the method was tested with nickel containing (25 or 38% by weight), well-characterized multi-walled CNT aerosols generated freshly in the lab for each experiment. Two chemical reactions were investigated, of which the oxidation of CO to CO2 at 470°C was found to be more effective, because nearly 100% of the nickel was exposed at that temperature by burning off the carbon, giving a linear relationship between CO conversion and nickel mass. Based on the investigated aerosols, a lower detection limit of 1 μg of sampled nickel was estimated. This translates into sampling times ranging from minutes to about one working day, depending on airborne CNT concentration and catalyst content, as well as sampling flow rate. The time for the subsequent chemical analysis is on the order of minutes, regardless of the time required to accumulate the sample and can be done on site.

  9. Continuous Carbon Nanotube-Based Fibers and Films for Applications Requiring Enhanced Heat Dissipation.

    Science.gov (United States)

    Liu, Peng; Fan, Zeng; Mikhalchan, Anastasiia; Tran, Thang Q; Jewell, Daniel; Duong, Hai M; Marconnet, Amy M

    2016-07-13

    The production of continuous carbon nanotube (CNT) fibers and films has paved the way to leverage the superior properties of individual carbon nanotubes for novel macroscale applications such as electronic cables and multifunctional composites. In this manuscript, we synthesize fibers and films from CNT aerogels that are continuously grown by floating catalyst chemical vapor deposition (FCCVD) and measure thermal conductivity and natural convective heat transfer coefficient from the fiber and film. To probe the mechanisms of heat transfer, we develop a new, robust, steady-state thermal characterization technique that enables measurement of the intrinsic fiber thermal conductivity and the convective heat transfer coefficient from the fiber to the surrounding air. The thermal conductivity of the as-prepared fiber ranges from 4.7 ± 0.3 to 28.0 ± 2.4 W m(-1) K(-1) and depends on fiber volume fraction and diameter. A simple nitric acid treatment increases the thermal conductivity by as much as a factor of ∼3 for the fibers and ∼6.7 for the thin films. These acid-treated CNT materials demonstrate specific thermal conductivities significantly higher than common metals with the same absolute thermal conductivity, which means they are comparatively lightweight, thermally conductive fibers and films. Beyond thermal conductivity, the acid treatment enhances electrical conductivity by a factor of ∼2.3. Further, the measured convective heat transfer coefficients range from 25 to 200 W m(-2) K(-1) for all fibers, which is higher than expected for macroscale materials and demonstrates the impact of the nanoscale CNT features on convective heat losses from the fibers. The measured thermal and electrical performance demonstrates the promise for using these fibers and films in macroscale applications requiring effective heat dissipation.

  10. Carbon nanotube-based glucose oxidase nanocomposite anode materials for bio-fuel cells

    Science.gov (United States)

    Dudzik, Jonathan

    The field of nanotechnology has benefited medicine, science, and engineering. The advent of Carbon Nanotubes (CNTs) and protein-inorganic interfacing have received much attention due to their unique nanostructures which can be modified to act as a scaffold to house proteins or create nanowires. The current trend incorporates the robustness and specificity characteristics of proteins to the mechanical strength, enlarged surface area, and conductive capabilities emblematic of their inorganic counterparts. Bio-Fuel Cells (BFCs) and Biosensors remain at the forefront and devices such as implantable glucose monitors are closer to realization than ever before. This research strives to exploit potential energy from the eukaryotic enzyme Glucose Oxidase (GOx) during oxidation of its substrate, glucose. During this process, a two-electron transfer occurs at its two FAD redox centres which can be harnessed via an electrochemical setup involving a Multi-Walled Carbon Nanotube (MWCNTs) modified electrode. The objective is to develop a MWCNT-GOx bionanocomposite capable of producing and sustaining a competitive power output. To help with this aim, investigation into a crosslinked enzyme cluster (CEC) immobilization technique is envisioned to amplify power output due to its highly concentrated, reusable, and thermally stable characteristics. Numerous CEC-GOx-MWCNT composites were fabricated with the highest initial output reaching 170 muW/cm 2. It was hypothesized that the carbohydrate moiety increased tunnelling distance and therefore hindered electron transfer. Efforts to produce a recombinant GOx without the encumbrance were unsuccessful. Two sub-clone constructs were explored and although a recombinant protein was identified, it was not confirmed to be GOx. BFC testing on bionanocomposites integrating non-glycosylated GOx could not be performed although there remains a strong contention that the recombinant would demonstrate superior power densities in comparison to its

  11. Carbon Nanotube Based Nanotechnology for NASA Mission Needs and Societal Applications

    Science.gov (United States)

    Li, Jing; Meyyappan, M.

    2011-01-01

    Carbon nanotubes (CNT) exhibit extraordinary mechanical properties and unique electronic properties and therefore, have received much attention for more than a decade now for a variety of applications ranging from nanoelectronics, composites to meeting needs in energy, environmental and other sectors. In this talk, we focus on some near term potential of CNT applications for both NASA and other Agency/societal needs. The most promising and successful application to date is a nano chem sensor at TRL 6 that uses a 16-256 sensor array in the construction of an electronic nose. Pristine, doped, functionalized and metal-loaded SWCNTs are used as conducting materials to provide chemical variation across the individual elements of the sensor array. This miniaturized sensor has been incorporated in an iPhone for homeland security applications. Gases and vapors relevant to leak detection in crew vehicles, biomedical, mining, chemical threats, industrial spills and others have been demonstrated. SWCNTs also respond to radiation exposure via a change in conductivity and therefore, a similar strategy is being pursued to construct a radiation nose to identify radiation sources (gamma, protons, neutrons, X-ray, etc.) with their energy levels. Carbon nanofibers (CNFs) grown using plasma enhanced CVD typically are vertical, individual, freestanding structures and therefore, are ideal for construction of nanoelectrodes. A nanoelectrode array (NEA) can be the basis for an affinity-based biosensor to meet the needs in applications such as lab-on-a-chip, environmental monitoring, cancer diagnostics, biothreat monitoring, water and food safety and others. A couple of demonstrations including detection of e-coli and ricin will be discussed. The NEA is also useful for implantation in the brain for deep brain stimulation and neuroengineering applications. Miniaturization of payload such as science instrumentation and power sources is critical to reduce launch costs. High current density

  12. Modeling of Energy Transfer for Carbon Nanotube-Based Precision Machining

    Science.gov (United States)

    Wong, Basil T.; Pinar Menguc, M.; Vallance, R. Ryan; Rao, Apparao M.

    2003-03-01

    INTRODUCTION Possible use of electron emission from carbon nanotubes (CNTs) for precision machining has been realized only recently. It is hypothesized that by coupling CNT electron emission with radiation transfer mechanism nano-scaled machining can be achieved. A laser, for example, can be used to raise the temperature of the workpiece near its melting point, and a carbon nanotube is then used to transfer additional energy required to the workpiece to complete the removal of minute amount of materials for nanomachining process. To investigate this hypothesis, a detailed numerical/analytical study is conducted. Electron transfer is modeled using a Monte Carlo approach, and a detailed radiation transfer model, including Fresnel reflections is adapted. Based on the numerical simulations we found that a power of one-tenth of a watt is required from a CNT alone to raise the temperature of gold beyond its melting point. However, using a localized heating with a laser, the required power can be reduced by roughly more than a half. This paper outlines the details of the numerical simulation and establishes a set of design guidelines for future nanomachining modalities. We are interested in nanomachining using the CNTs. Our objective is to determine if we can effectively remove tens of atoms from the workpiece by electron transfer from a single CNT and proper laser heating from either side of the workpiece. To reach our goal, energy transfer from a single CNT may not be sufficient. One way to overcome this setback is to preheat the workpiece to a certain temperature through a bulk heating, and using a subsequent localized heating by the laser beam to further increase the temperature of a specified location. Thus only a minimum amount of energy is required from the nanotube to process the material, i.e. to remove tens of atoms. Due to the complicated interactions between propagating electrons and the solid material, obtaining a physically realistic theoretical analysis

  13. Estimation of local concentration from measurements of stochastic adsorption dynamics using carbon nanotube-based sensors

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Hong; Lee, Jay H. [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Braatz, Richard D. [Massachusetts Institute of Technology (MIT), Cambridge (United States)

    2016-01-15

    This paper proposes a maximum likelihood estimation (MLE) method for estimating time varying local concentration of the target molecule proximate to the sensor from the time profile of monomolecular adsorption and desorption on the surface of the sensor at nanoscale. Recently, several carbon nanotube sensors have been developed that can selectively detect target molecules at a trace concentration level. These sensors use light intensity changes mediated by adsorption or desorption phenomena on their surfaces. The molecular events occurring at trace concentration levels are inherently stochastic, posing a challenge for optimal estimation. The stochastic behavior is modeled by the chemical master equation (CME), composed of a set of ordinary differential equations describing the time evolution of probabilities for the possible adsorption states. Given the significant stochastic nature of the underlying phenomena, rigorous stochastic estimation based on the CME should lead to an improved accuracy over than deterministic estimation formulated based on the continuum model. Motivated by this expectation, we formulate the MLE based on an analytical solution of the relevant CME, both for the constant and the time-varying local concentrations, with the objective of estimating the analyte concentration field in real time from the adsorption readings of the sensor array. The performances of the MLE and the deterministic least squares are compared using data generated by kinetic Monte Carlo (KMC) simulations of the stochastic process. Some future challenges are described for estimating and controlling the concentration field in a distributed domain using the sensor technology.

  14. Sensing human physiological response using wearable carbon nanotube-based fabrics

    Science.gov (United States)

    Wang, Long; Loh, Kenneth J.; Koo, Helen S.

    2016-04-01

    Flexible and wearable sensors for human monitoring have received increased attention. Besides detecting motion and physical activity, measuring human vital signals (e.g., respiration rate and body temperature) provide rich data for assessing subjects' physiological or psychological condition. Instead of using conventional, bulky, sensing transducers, the objective of this study was to design and test a wearable, fabric-like sensing system. In particular, multi-walled carbon nanotube (MWCNT)-latex thin films of different MWCNT concentrations were first fabricated using spray coating. Freestanding MWCNT-latex films were then sandwiched between two layers of flexible fabric using iron-on adhesive to form the wearable sensor. Second, to characterize its strain sensing properties, the fabric sensors were subjected to uniaxial and cyclic tensile load tests, and they exhibited relatively stable electromechanical responses. Finally, the wearable sensors were placed on a human subject for monitoring simple motions and for validating their practical strain sensing performance. Overall, the wearable fabric sensor design exhibited advances such as flexibility, ease of fabrication, light weight, low cost, noninvasiveness, and user comfort.

  15. Processing strategies for smart electroconductive carbon nanotube-based bioceramic bone grafts

    Science.gov (United States)

    Mata, D.; Oliveira, F. J.; Ferreira, N. M.; Araújo, R. F.; Fernandes, A. J. S.; Lopes, M. A.; Gomes, P. S.; Fernandes, M. H.; Silva, R. F.

    2014-04-01

    Electroconductive bone grafts have been designed to control bone regeneration. Contrary to polymeric matrices, the translation of the carbon nanotube (CNT) electroconductivity into oxide ceramics is challenging due to the CNT oxidation during sintering. Sintering strategies involving reactive-bed pressureless sintering (RB + P) and hot-pressing (HP) were optimized towards prevention of CNT oxidation in glass/hydroxyapatite (HA) matrices. Both showed CNT retentions up to 80%, even at 1300 °C, yielding an increase of the electroconductivity in ten orders of magnitude relative to the matrix. The RB + P CNT compacts showed higher electroconductivity by ˜170% than the HP ones due to the lower damage to CNTs of the former route. Even so, highly reproducible conductivities with statistical variation below 5% and dense compacts up to 96% were only obtained by HP. The hot-pressed CNT compacts possessed no acute toxicity in a human osteoblastic cell line. A normal cellular adhesion and a marked orientation of the cell growth were observed over the CNT composites, with a proliferation/differentiation relationship favouring osteoblastic functional activity. These sintering strategies offer new insights into the sintering of electroconductive CNT containing bioactive ceramics with unlimited geometries for electrotherapy of the bone tissue.

  16. Development of functionalized multi-walled carbon-nanotube-based alginate hydrogels for enabling biomimetic technologies

    Science.gov (United States)

    Joddar, Binata; Garcia, Eduardo; Casas, Atzimba; Stewart, Calvin M.

    2016-08-01

    Alginate is a hydrogel commonly used for cell culture by ionically crosslinking in the presence of divalent Ca2+ ions. However these alginate gels are mechanically unstable, not permitting their use as scaffolds to engineer robust biological bone, breast, cardiac or tumor tissues. This issue can be addressed via encapsulation of multi-walled carbon nanotubes (MWCNT) serving as a reinforcing phase while being dispersed in a continuous phase of alginate. We hypothesized that adding functionalized MWCNT to alginate, would yield composite gels with distinctively different mechanical, physical and biological characteristics in comparison to alginate alone. Resultant MWCNT-alginate gels were porous, and showed significantly less degradation after 14 days compared to alginate alone. In vitro cell-studies showed enhanced HeLa cell adhesion and proliferation on the MWCNT-alginate compared to alginate. The extent of cell proliferation was greater when cultured atop 1 and 3 mg/ml MWCNT-alginate; although all MWCNT-alginates lead to enhanced cell cluster formation compared to alginate alone. Among all the MWCNT-alginates, the 1 mg/ml gels showed significantly greater stiffness compared to all other cases. These results provide an important basis for the development of the MWCNT-alginates as novel substrates for cell culture applications, cell therapy and tissue engineering.

  17. Wearable carbon nanotube-based fabric sensors for monitoring human physiological performance

    Science.gov (United States)

    Wang, Long; Loh, Kenneth J.

    2017-05-01

    A target application of wearable sensors is to detect human motion and to monitor physical activity for improving athletic performance and for delivering better physical therapy. In addition, measuring human vital signals (e.g., respiration rate and body temperature) provides rich information that can be used to assess a subject’s physiological or psychological condition. This study aims to design a multifunctional, wearable, fabric-based sensing system. First, carbon nanotube (CNT)-based thin films were fabricated by spraying. Second, the thin films were integrated with stretchable fabrics to form the fabric sensors. Third, the strain and temperature sensing properties of sensors fabricated using different CNT concentrations were characterized. Furthermore, the sensors were demonstrated to detect human finger bending motions, so as to validate their practical strain sensing performance. Finally, to monitor human respiration, the fabric sensors were integrated with a chest band, which was directly worn by a human subject. Quantification of respiration rates were successfully achieved. Overall, the fabric sensors were characterized by advantages such as flexibility, ease of fabrication, lightweight, low-cost, noninvasiveness, and user comfort.

  18. A heparin-functionalized carbon nanotube-based affinity biosensor for dengue virus.

    Science.gov (United States)

    Wasik, Daniel; Mulchandani, Ashok; Yates, Marylynn V

    2017-05-15

    Dengue virus is an arthropod-borne virus transmitted primarily by Aedes mosquitos and is major cause of disease in tropical and subtropical regions. Colloquially known as Dengue Fever, infection can cause hemorrhagic disorders and death in humans and non-human primates. We report a novel electronic biosensor based on a single-walled carbon nanotube network chemiresistive transducer that is functionalized with heparin for low-cost, label-free, ultra-sensitive, and rapid detection of whole dengue virus (DENV). Heparin, an analog of the heparan sulfate proteoglycans that are receptors for dengue virus during infection of Vero cells and hepatocytes, was used for the first time in a biosensor as a biorecognition element instead of traditional antibody. Detection of DENV in viral culture supernatant has similar sensitivity as the corresponding viral titer in phosphate buffer despite the presence of growth media and Vero cell lysate. The biosensor demonstrated sensitivity within the clinically relevant range for humans and infected Aedes aegypti. It has potential application in clinical diagnosis and can improve point-of-care diagnostics of dengue infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Sustaining GHz oscillation of carbon nanotube based oscillators via a MHz frequency excitation

    Science.gov (United States)

    Motevalli, Benyamin; Taherifar, Neda; Zhe Liu, Jefferson

    2016-05-01

    There have been intensive studies to investigate the properties of gigahertz nano-oscillators based on multi-walled carbon nanotubes (MWCNTs). Many of these studies, however, revealed that the unique telescopic translational oscillations in such devices would damp quickly due to various energy dissipation mechanisms. This challenge remains the primary obstacle against its practical applications. Herein, we propose a design concept in which a GHz oscillation could be re-excited by a MHz mechanical motion. This design involves a triple-walled CNT, in which sliding of the longer inner tube at a MHz frequency can re-excite and sustain a GHz oscillation of the shorter middle tube. Our molecular dynamics (MD) simulations prove this design concept at ˜10 nm scale. A mathematical model is developed to explore the feasibility at a larger size scale. As an example, in an oscillatory system with the CNT’s length above 100 nm, the high oscillatory frequency range of 1.8-3.3 GHz could be excited by moving the inner tube at a much lower frequency of 53.4 MHz. This design concept together with the mechanical model could energize the development of GHz nano-oscillators in miniaturized electro-mechanical devices.

  20. Performance of a 60 F carbon nanotubes-based supercapacitor for hybrid power sources

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Wang; Dianbo Ruan; Zheng You; Yiqiang Lu; Qiqian Sha

    2005-01-01

    A supercapacitor based on charge storage at the interface between a high surface area carbon nanotube electrode and a LiClO4/PC electrolyte was assembled. The performance of the capacitor depends on not only the material used in the cell but also the construction of the cell. From a constant charge-discharge test, the capacitance of 60 F was obtained. The performance of the power power supercapacitor were demonstrated with a cell of the maximum operating voltage of 2.5 V. A hybrid power source consisting of a lithium ionic battery and the 60 F supercapacitor was demonstrated to power successfully a simulated power load encountered in GSM portable communication equipment. The addition of the supercapacitor to the power train of a cellular phone results in significantly more energy from the battery being used by the load. The experiments indicate that more than 33.8% energy is utilized by load and less stored energy is dissipated within the battery for each charge-discharge cycle.

  1. Substrate pre-treatment of flexible material for printed electronics with carbon nanotube based ink

    Science.gov (United States)

    Denneulin, Aurore; Bras, Julien; Blayo, Anne; Neuman, Charles

    2011-02-01

    In this work, an innovative solution was developed in order to make paper-based material, used traditionally in the packaging and labelling industries, compatible with the printing of functional conductive inks. In order to avoid the deterioration of the ink functionalities due to different paper properties, a UV-curing inkjettable primer layer was developed. This pre-treatment enables homogeneous surface properties such as smoothness, absorption capacity and surface energy to be obtained, for almost all the examined substrates. To confirm the positive impact of such pre-treatment, conductivity has been measured when using a new conductive ink, combining the processability of the PEDOT-PSS conductive polymer with the high electrical properties of carbon nanotubes (CNTs). Significant improvement has been measured for all paper materials and similar conductivity (close to reference PET film) has been obtained whatever the substrate involved. This pre-treatment now makes it possible to consider paper-based material as a potential substrate for printed electronics. In this case, the substrate adaptation technique offers an innovative solution to produce low-cost and flexible electronics.

  2. Scratch-resistant, highly conductive, and high-strength carbon nanotube-based composite yarns.

    Science.gov (United States)

    Liu, Kai; Sun, Yinghui; Lin, Xiaoyang; Zhou, Ruifeng; Wang, Jiaping; Fan, Shoushan; Jiang, Kaili

    2010-10-26

    High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

  3. Carbon Nanotube-Based Digital Vacuum Electronics and Miniature Instrumentation for Space Exploration

    Science.gov (United States)

    Manohara, H.; Toda, R.; Lin, R. H.; Liao, A.; Mojarradi, M.

    2010-01-01

    JPL has developed high performance cold cathodes using arrays of carbon nanotube bundles that produce > 15 A/sq cm at applied fields of 5 to 8 V/micron without any beam focusing. They have exhibited robust operation in poor vacuums of 10(exp -6) to 10(exp -4) Torr- a typically achievable range inside hermetically sealed microcavities. Using these CNT cathodes JPL has developed miniature X-ray tubes capable of delivering sufficient photon flux at acceleration voltages of <20kV to perform definitive mineralogy on planetary surfaces; mass ionizers that offer two orders of magnitude power savings, and S/N ratio better by a factor of five over conventional ionizers. JPL has also developed a new class of programmable logic gates using CNT vacuum electronics potentially for Venus in situ missions and defense applications. These digital vacuum electronic devices are inherently high-temperature tolerant and radiation insensitive. Device design, fabrication and DC switching operation at temperatures up to 700 C are presented in this paper.

  4. Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring in civil engineering

    Energy Technology Data Exchange (ETDEWEB)

    Lebental, B [Universite Paris-Est, IFSTTAR, 58 boulevard Lefebvre, 75732 Paris Cedex 15 (France); Chainais, P [INRIA Lille-Nord Europe (SEQUEL), 40 avenue Halley, 59650 Villeneuve d' Ascq (France); Chenevier, P [SPEC, IRAMIS, CEA/Saclay, Gif-sur-Yvette (France); Chevalier, N; Delevoye, E; Fabbri, J-M; Nicoletti, S; Renaux, P; Ghis, A, E-mail: berengere.lebental@ifsttar.fr [CEA, LETI, MINATEC Campus, F-38054 Grenoble (France)

    2011-09-30

    Structural health monitoring of porous materials such as concrete is becoming a major component in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large numbers within a porous material in order to provide information on its durability by monitoring in situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration over a large range of frequencies spanning from 100 kHz to 5 MHz.

  5. Carbon Nanotube-Based Digital Vacuum Electronics and Miniature Instrumentation for Space Exploration

    Science.gov (United States)

    Manohara, H.; Toda, R.; Lin, R. H.; Liao, A.; Mojarradi, M.

    2010-01-01

    JPL has developed high performance cold cathodes using arrays of carbon nanotube bundles that produce > 15 A/sq cm at applied fields of 5 to 8 V/micron without any beam focusing. They have exhibited robust operation in poor vacuums of 10(exp -6) to 10(exp -4) Torr- a typically achievable range inside hermetically sealed microcavities. Using these CNT cathodes JPL has developed miniature X-ray tubes capable of delivering sufficient photon flux at acceleration voltages of <20kV to perform definitive mineralogy on planetary surfaces; mass ionizers that offer two orders of magnitude power savings, and S/N ratio better by a factor of five over conventional ionizers. JPL has also developed a new class of programmable logic gates using CNT vacuum electronics potentially for Venus in situ missions and defense applications. These digital vacuum electronic devices are inherently high-temperature tolerant and radiation insensitive. Device design, fabrication and DC switching operation at temperatures up to 700 C are presented in this paper.

  6. Quantitative Conductive Atomic Force Microscopy on Single-Walled Carbon Nanotube-Based Polymer Composites.

    Science.gov (United States)

    Bârsan, Oana A; Hoffmann, Günter G; van der Ven, Leendert G J; de With, Gijsbertus

    2016-08-03

    Conductive atomic force microscopy (C-AFM) is a valuable technique for correlating the electrical properties of a material with its topographic features and for identifying and characterizing conductive pathways in polymer composites. However, aspects such as compatibility between tip material and sample, contact force and area between the tip and the sample, tip degradation and environmental conditions render quantifying the results quite challenging. This study aims at finding the suitable conditions for C-AFM to generate reliable, reproducible, and quantitative current maps that can be used to calculate the resistance in each point of a single-walled carbon nanotube (SWCNT) network, nonimpregnated as well as impregnated with a polymer. The results obtained emphasize the technique's limitation at the macroscale as the resistance of these highly conductive samples cannot be distinguished from the tip-sample contact resistance. Quantitative C-AFM measurements on thin composite sections of 150-350 nm enable the separation of sample and tip-sample contact resistance, but also indicate that these sections are not representative for the overall SWCNT network. Nevertheless, the technique was successfully used to characterize the local electrical properties of the composite material, such as sample homogeneity and resistance range of individual SWCNT clusters, at the nano- and microscale.

  7. Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring in civil engineering.

    Science.gov (United States)

    Lebental, B; Chainais, P; Chenevier, P; Chevalier, N; Delevoye, E; Fabbri, J-M; Nicoletti, S; Renaux, P; Ghis, A

    2011-09-30

    Structural health monitoring of porous materials such as concrete is becoming a major component in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large numbers within a porous material in order to provide information on its durability by monitoring in situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration over a large range of frequencies spanning from 100 kHz to 5 MHz.

  8. Carbon nanotube-based nanocarriers: the importance of keeping it clean.

    Science.gov (United States)

    Delogu, Lucia G; Stanford, Stephanie M; Santelli, Eugenio; Magrini, Andrea; Bergamaschi, Antonio; Motamedchaboki, Khatereh; Rosato, Nicola; Mustelin, Tomas; Bottini, Nunzio; Bottini, Massimo

    2010-08-01

    Nanotechnology-introduced materials have promising applications as nanocarriers for drugs, peptides, proteins and nucleic acids. Several studies showed that the geometry (shape and size) and chemical properties of nanoparticles affect the kinetics and pathways of cellular uptake and their intracellular trafficking and signaling. Accurate physico-chemical characterization of nanoparticles customarily precedes their use in cell biology and in vivo experiments. However, a fact that is easily overlooked is that nanomaterials decorated with organic matter or resuspended in aqueous buffers can be theoretically contaminated by fungal and bacterial microorganisms. While investigating the effects of extensively characterized PEGylated carbon nanotubes (PNTs) on T lymphocyte activation, we demonstrated bacterial contamination of PNTs, which correlated with low reproducibility and artifacts in cell signaling assays. Contamination and artifacts were easily eliminated by preparing the materials in sterile conditions. We propose that simple sterile preparation procedures should be adopted and sterility evaluation of nanoparticles should be customarily performed, prior to assessing nanoparticle intracellular internalization, trafficking and their effects on cells and entire organisms.

  9. Morphology of PEDOT:PSS/SWCNT Composites: Insight into Carbon Nanotube Based Organic Thermoelectric Matrices

    Science.gov (United States)

    Etampawala, Thusitha; Tehrani, Mehran; Dadmun, Mark

    2015-03-01

    Carbon nanotube (CNT) loaded poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanocomposites are promising materials as the active layer in organic thermoelectric devices. Improvements in the thermoelectric performance of these nanocomposites have been hampered by the lack of an understanding of the correlation between thermo-electrical performance and morphology. In this study, the morphology of highly conducting single walled CNT/PEDOT:PSS nanocomposites were probed by small and ultra-small angle neutron scattering (SANS and USANS respectively) as a function of CNT loading (10wt%, 30wt% and 50wt%,), sonication duration to control the CNT dispersion, and presence and absence of ethylene glycol (EG) in the deposition solution of PEDOT:PSS. The morphology of these composites is currently being correlated to their thermo-electric performance. The SANS and USANS profiles were analyzed with the hierarchical Beaucage model. Further, the USANS data were fit to a two ellipsoidal form factor, which is consistent with the analysis of the USANS data by the Beaucage model and SEM results. These results reveal that the sonication duration and presence of EG effectively de-bundle the CNTs and disperse them in the PEDOT:PSS matrix.

  10. Substrate pre-treatment of flexible material for printed electronics with carbon nanotube based ink

    Energy Technology Data Exchange (ETDEWEB)

    Denneulin, Aurore, E-mail: Aurore@polypore.fr [Polypore - 27, bd Louise Michel, F-92230 Gennevilliers (France); Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) (UMR 5518 CNRS-CTP-INPG), Grenoble Institute of Technology, INP Grenoble - PAGORA, 461 Rue de la Papeterie, BP 65, 38402 St Martin d' Heres Cedex (France); Bras, Julien, E-mail: Julien.Bras@grenoble-inp.fr [Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) (UMR 5518 CNRS-CTP-INPG), Grenoble Institute of Technology, INP Grenoble - PAGORA, 461 Rue de la Papeterie, BP 65, 38402 St Martin d' Heres Cedex (France); Blayo, Anne, E-mail: Anne.Blayo@grenoble-inp.fr [Laboratory of Pulp and Paper Science and Graphic Arts (LGP2), UMR 5518 CNRS-CTP-INPG, Grenoble Institute of Technology (INP Grenoble - PAGORA), 461 Rue de la Papeterie, BP 65, 38402 St Martin d' Heres Cedex (France); Neuman, Charles [Polypore - 27, bd Louise Michel, F-92230 Gennevilliers (France)

    2011-02-01

    In this work, an innovative solution was developed in order to make paper-based material, used traditionally in the packaging and labelling industries, compatible with the printing of functional conductive inks. In order to avoid the deterioration of the ink functionalities due to different paper properties, a UV-curing inkjettable primer layer was developed. This pre-treatment enables homogeneous surface properties such as smoothness, absorption capacity and surface energy to be obtained, for almost all the examined substrates. To confirm the positive impact of such pre-treatment, conductivity has been measured when using a new conductive ink, combining the processability of the PEDOT-PSS conductive polymer with the high electrical properties of carbon nanotubes (CNTs). Significant improvement has been measured for all paper materials and similar conductivity (close to reference PET film) has been obtained whatever the substrate involved. This pre-treatment now makes it possible to consider paper-based material as a potential substrate for printed electronics. In this case, the substrate adaptation technique offers an innovative solution to produce low-cost and flexible electronics.

  11. Carbon nanotube-based polymer nanocomposites: Fractal network to hierarchical morphology

    Science.gov (United States)

    Chatterjee, Tirtha

    The dispersion of anisotropic nanoparticles such as single-walled carbon nanotubes in polymeric matrices promises the ability to develop advanced materials with controlled and tailored combinations of properties. However, dispersion of such nanotubes in a polymer matrix is an extremely challenging task due to strong attractive interactions between the nanotubes. The successful dispersion of single-walled carbon nanotubes in poly(ethylene oxide) using an anionic surfactant (lithium dodecyl sulfate) as compatibilizer is reported here. The geometrical percolation threshold (pc, in vol %) of nanotubes, as revealed by melt-state rheological measurements, is found to be at ˜ 0.09 vol % loading, which corresponds to an effective tube anisotropy of ˜ 650. The system shows an even earlier development of the electrical percolation at 0.03 vol % SWNT loading as obtained by electrical conductivity measurements. In their quiescent state, the nanotubes show hierarchical fractal network (mass fractal dimension ˜ 2.3 +/- 0.2) made of aggregated flocs. Inside the floc, individual or small bundles of nanotubes overlap each other to form a dense mesh. The interfloc interactions provides the stress bearing capacity for these nano composites and are responsible for the unique modulus scaling of these systems (˜(p-pc)delta, 3.0 ≤ delta ≤ 4.5). The interaction is inversely related to the particle dispersion state, which influences the absolute values of the viscoelastic parameters. As a direct consequence of the self-similar fractal network, the linear flow properties display 'time-temperature-composition' superposition. This superposability can be extended for non-linear deformations when the non-linear properties are scaled by the local strain experienced by the elements of the network. More interestingly, under steady shear, these nanocomposites show network-independent behavior. The absolute stress value is a function of the nanotube loading, but the characteristic time

  12. Modeling the electromechanical and strain response of carbon nanotube-based nanocomposites

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Burton, Andrew R.; Loyola, Bryan R.

    2014-04-01

    Over the last few decades, carbon nanotube (CNT)-based thin films or nanocomposites have been widely investigated as a multifunctional material. The proposed applications extend beyond sensing, ultra-strong coatings, biomedical grafts, and energy harvesting, among others. In particular, thin films characterized by a percolated and random distribution of CNTs within a flexible polymeric matrix have been shown to change its electrical properties in response to applied strains. While a plethora of experimental work has been conducted, modeling their electromechanical response remains challenging. Furthermore, their design and optimization require the derivation of accurate electromechanical models that could predict thin film response to applied strains. Thus, the objective of this study is to implement a percolation-based piezoresistive model that could explain the underlying mechanisms for strain sensing. First, a percolation-based model with randomly distributed, straight CNTs was developed in MATLAB. Second, the number of CNTs within a unit area was varied to explore its influence on percolation probability. Then, to understand how the film's electrical properties respond to strain, two different models were implemented. Both models calculated the geometrical response of the film and CNTs due to applied uniaxial strains. The first model considered the fact that the electrical resistance of individual CNTs changed depending solely on its length between junctions. The other model further explored the idea of incorporating strain sensitivity of individual CNTs. The electromechanical responses and the strain sensitivities of the two models were compared by calculating how their bulk resistance varied due to applied tensile and compressive strains. The numerical model results were then qualitatively compared to experimental results reported in the literature.

  13. Protein functionalized carbon nanotubes-based smart lab-on-a-chip.

    Science.gov (United States)

    Ali, Md Azahar; Solanki, Pratima R; Srivastava, Saurabh; Singh, Samer; Agrawal, Ved V; John, Renu; Malhotra, Bansi D

    2015-03-18

    A label-free impedimetric lab on a chip (iLOC) is fabricated using protein (bovine serum albumin) and antiapolipoprotein B functionalized carbon nanotubes-nickel oxide (CNT-NiO) nanocomposite for low-density lipoprotein (LDL) detection. The antiapolipoprotein B (AAB) functionalized CNT-NiO microfluidic electrode is assembled with polydimethylsiloxane rectangular microchannels (cross section: 100 × 100 μm). Cytotoxicity of the synthesized CNTs, NiO nanoparticles, and CNT-NiO nanocomposite has been investigated in the presence of lung epithelial cancer A549 cell line using MTT assay. The CNT-NiO nanocomposite shows higher cell viability at a concentration of 6.5 μg/mL compared to those using individual CNTs. The cell viability and proliferation studies reveal that the toxicity increases with increasing CNTs concentration. The X-ray photoelectron spectroscopy studies have been used to quantify the functional groups present on the CNT-NiO electrode surface before and after proteins functionalization. The binding kinetic and electrochemical activities of CNT-NiO based iLOC have been conducted using chronocoulometry and impedance spectroscopic techniques. This iLOC shows excellent sensitivity of 5.37 kΩ (mg/dL)(-1) and a low detection limit of 0.63 mg/dL in a wide concentration range (5-120 mg/dL) of LDL. The binding kinetics of antigen-antibody interaction of LDL molecules reveal a high association rate constant (8.13 M(-1) s(-1)). Thus, this smart nanocomposite (CNT-NiO) based iLOC has improved stability and reproducibility and has implications toward in vivo diagnostics.

  14. Synthesis, Characterization and Utility of Carbon Nanotube Based Hybrid Sensors in Bioanalytical Applications

    Science.gov (United States)

    Badhulika, Sushmee

    The detection of gaseous analytes and biological molecules is of prime importance in the fields of environmental pollution control, food and water - safety and analysis; and medical diagnostics. This necessitates the development of advanced and improved technology that is reliable, inexpensive and suitable for high volume production. The conventional sensors are often thin film based which lack sensitivity due to the phenomena of current shunting across the charge depleted region when an analyte binds with them. One dimensional (1-D) nanostructures provide a better alternative for sensing applications by eliminating the issue of current shunting due to their 1-D geometries and facilitating device miniaturization and low power operations. Carbon nanotubes (CNTs) are 1-D nanostructures that possess small size, high mechanical strength, high electrical and thermal conductivity and high specific area that have resulted in their wide spread applications in sensor technology. To overcome the issue of low sensitivity of pristine CNTs and to widen their scope, hybrid devices have been fabricated that combine the synergistic properties of CNTs along with materials like metals and conducting polymers (CPs). CPs exhibit electronic, magnetic and optical properties of metals and semiconductors while retaining the processing advantages of polymers. Their high chemical sensitivity, room temperature operation and tunable charge transport properties has made them ideal for use as transducing elements in chemical sensors. In this dissertation, various CNT based hybrid devices such as CNT-conducting polymer and graphene-CNT-metal nanoparticles based sensors have been developed and demonstrated towards bioanalytical applications such as detection of volatile organic compounds (VOCs) and saccharides. Electrochemical polymerization enabled the synthesis of CPs and metal nanoparticles in a simple, cost effective and controlled way on the surface of CNT based platforms thus resulting in

  15. Investigations of niobium carbide contact for carbon-nanotube-based devices

    Science.gov (United States)

    Huang, L.; Chor, E. F.; Wu, Y.; Guo, Z.

    2010-03-01

    Single-walled carbon nanotube (SWCNT) field effect transistors (FETs) with Nb contacts have been fabricated and upon annealing in vacuum at 700 °C for 1 h, niobium carbide (Nb2C) is formed at the Nb/SWCNT interface. The Nb2C/SWCNT contacts demonstrate a very small Schottky barrier height of ~ 18 meV (decreased by > 80% relative to that of pristine Nb/SWCNT contact of ~ 98 meV) to p-type transport. This is attributed to the higher work function of Nb2C (~5.2 eV) than Nb (~4.3 eV) and better bonding between Nb2C and SWCNTs. The performance of Nb2C-contacted SWCNT FETs is as follows: the p-channel ON current is as high as 0.5 µA at VDS = 0.1 V, the ION/IOFF ratio is up to ~ 105 and the subthreshold slope is ~ 550 mV/dec, which is as good as that of titanium carbide (TiC-) and Pd-contacted SWCNT FETs. Compared with TiC, Nb2C contacts yield more unipolar p-type SWCNT FETs, as a result of the Nb2Cs higher work function. More importantly, Nb2C contacts can form near-ohmic contacts to both large-(>=1.6 nm) and small-diameter (~1 nm) SWCNTs, while Pd can only form near-ohmic contacts for large-diameter SWCNTs. Moreover, the Nb2C contacts demonstrate good stability in air.

  16. Investigations of niobium carbide contact for carbon-nanotube-based devices

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L; Chor, E F [Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, Blk E3 02-07, Engineering Drive 3, Singapore 117576 (Singapore); Wu, Y [Information Storage Materials Laboratory, Department of Electrical and Computer Engineering, National University of Singapore, WS2, 03-25, 1 Engineering Drive 3, Singapore 117576 (Singapore); Guo, Z, E-mail: g0403704@nus.edu.sg [Data Storage Institute, 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2010-03-05

    Single-walled carbon nanotube (SWCNT) field effect transistors (FETs) with Nb contacts have been fabricated and upon annealing in vacuum at 700 deg. C for 1 h, niobium carbide (Nb{sub 2}C) is formed at the Nb/SWCNT interface. The Nb{sub 2}C/SWCNT contacts demonstrate a very small Schottky barrier height of {approx} 18 meV (decreased by > 80% relative to that of pristine Nb/SWCNT contact of {approx} 98 meV) to p-type transport. This is attributed to the higher work function of Nb{sub 2}C ({approx}5.2 eV) than Nb ({approx}4.3 eV) and better bonding between Nb{sub 2}C and SWCNTs. The performance of Nb{sub 2}C-contacted SWCNT FETs is as follows: the p-channel ON current is as high as 0.5 {mu}A at V{sub DS} = 0.1 V, the I{sub ON}/I{sub OFF} ratio is up to {approx} 10{sup 5} and the subthreshold slope is {approx} 550 mV/dec, which is as good as that of titanium carbide (TiC-) and Pd-contacted SWCNT FETs. Compared with TiC, Nb{sub 2}C contacts yield more unipolar p-type SWCNT FETs, as a result of the Nb{sub 2}Cs higher work function. More importantly, Nb{sub 2}C contacts can form near-ohmic contacts to both large-({>=}1.6 nm) and small-diameter ({approx}1 nm) SWCNTs, while Pd can only form near-ohmic contacts for large-diameter SWCNTs. Moreover, the Nb{sub 2}C contacts demonstrate good stability in air.

  17. Electron optics simulation for designing carbon nanotube based field emission x-ray source

    Science.gov (United States)

    Sultana, Shabana

    In this dissertation, electron optics simulation for designing carbon nanotube (CNT) based field emission x-ray source for medical imaging applications will be presented. However, for design optimization of x-ray tubes accurate electron beam optics simulation is essential. To facilitate design of CNT x-ray sources a commercial 3D finite element software has been chosen for extensive simulation. The results show that a simplified model of uniform electron field emission from the cathode surface is not sufficient when compared to experimental measurements. This necessitated the development of a refined model to describe a macroscopic field emission CNT cathode for electron beam optics simulations. The model emulates the random distribution of CNTs and the associated variation of local field enhancement factor. The main parameter of the model has been derived empirically from the experimentally measured I-V characteristics of the CNT cathode. Simulation results based on this model agree well with experiments which include measurements of the transmission rate and focus spot size. The model provides a consistent simulation platform for optimization of electron beam optics in CNT x-ray source design. A systematic study of electron beam optics in CNT x-ray tubes led to the development of a new generation of compact x-ray source with multiple pixels. A micro focus field emission x-ray source with a variable focal spot size has been fully characterized and evaluated. It has been built and successfully integrated into micro-CT scanners which are capable of dynamic cardiac imaging of free-breathing small animals with high spatial and temporal resolutions. In addition a spatially distributed high power multi-beam x-ray source has also been designed and integrated into a stationary digital breast tomosynthesis (s-DBT) configuration. This system has the potential to reduce the total scan time to 4 seconds and yield superior image quality in breast imaging.

  18. Characteristics of cesium ion sorption from aqueous solution on bentonite- and carbon nanotube-based composites

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shubin [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Han, Cho [Graduate School of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan); Wang, Xiangke [Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Faculty of Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Nagatsu, Masaaki, E-mail: tmnagat@ipc.shizuoka.ac.jp [Graduate School of Science and Technology, Shizuoka University, Hamamatsu 432-8561 (Japan); Graduate School of Engineering, Shizuoka University, Hamamatsu 432-8561 (Japan)

    2014-06-01

    Highlights: • The effects of cation and hydroxyl exchanges on Cs{sup +} sorption are investigated. • The CS-g-CNTs and the CS-g-bentonite composites are designed. • The effect of different cations on Cs{sup +} adsorption is detected. • The cation-exchange is much more effective in Cs{sup +} sorption than the hydroxyl group. • We give the future directions of new and selective adsorbents for Cs{sup +} ions. - Abstract: The technology development of Cs{sup +} capture from aqueous solution is crucial for the disposal of nuclear waste and still remains a significant challenge. Previous researches have been proven that ion exchanges with the cations and hydroxyl exchange are the main sorption mechanisms for Cs{sup +}. Therefore, how important are the cation exchange and the hydroxyl exchange mechanisms to Cs{sup +} sorption? And whether can we improve the sorption capacity of the material by increasing the amount of hydroxyl groups? With these in mind, we herein designed the chitosan-grafted carbon nanotubes (CS-g-CNTs) and the chitosan-grafted bentonite (CS-g-bentonite) by plasma-induced grafting method. The interactions of Cs{sup +} with CNTs, bentonite, CS-g-CNTs and CS-g-bentonite composites were investigated. The sorption of Cs{sup +} is mainly dominated by strong cation exchange in monovalent Group I and divalent Group II. And the cation-exchange mechanism is much more effective than the hydroxyl group exchange. The effect of hydroxyl groups is dependent on the property of the matrix. We cannot improve the Cs adsorption capacity of material for Cs{sup +} only by increasing the amount of hydroxyl groups in any case. The spatial structure and the cation-exchange capacity of the material are important factors for choosing the sorbent for Cs{sup +} removal from radioactive waste water.

  19. Single-walled carbon nanotube based transparent immunosensor for detection of a prostate cancer biomarker osteopontin

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Abhinav; Hong, Seongkyeol; Singh, Renu [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Jang, Jaesung, E-mail: jjang@unist.ac.kr [School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); Department of Biomedical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of); School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798 (Korea, Republic of)

    2015-04-15

    Highlights: • A transparent CNT immunosensor is presented for detection of a prostate cancer biomarker osteopontin. • This immunosensor showed a highly linear and reproducible behavior from 1 pg mL{sup −1} to 1 μg mL{sup −1}. • The limit of detection of the immunosensor was 0.3 pg mL{sup −1}. • This immunosensor demonstrated high selectivity against bovine serum albumin and human serum. - Abstract: Osteopontin (OPN) is involved in almost all steps of cancer development, and it is being investigated as a potential biomarker for a diagnosis and prognosis of prostate cancer. Here, we report a label-free, highly sensitive and transparent immunosensor based on single-walled carbon nanotubes (SWCNTs) for detection of OPN. A high density of −COOH functionalized SWCNTs was deposited between two gold/indium tin oxide electrodes on a glass substrate by dielectrophoresis. Monoclonal antibodies specific to OPN were covalently immobilized on the SWCNTs. Relative resistance change of the immunosensors was measured as the concentration of OPN in phosphate buffer saline (PBS) and human serum was varied from 1 pg mL{sup −1} to 1 μg mL{sup −1} for different channel lengths of 2, 5, and 10 μm, showing a highly linear and reproducible behavior (R{sup 2} > 97%). These immunosensors were also specific to OPN against another test protein, bovine serum albumin, PBS and human serum, showing that a limit of detection for OPN was 0.3 pg mL{sup −1}. This highly sensitive and transparent immunosensor has a great potential as a simple point-of-care test kit for various protein biomarkers.

  20. Development of a Carbon Nanotube-Based Micro-CT and its Applications in Preclinical Research

    Science.gov (United States)

    Burk, Laurel May

    Due to the dependence of researchers on mouse models for the study of human disease, diagnostic tools available in the clinic must be modified for use on these much smaller subjects. In addition to high spatial resolution, cardiac and lung imaging of mice presents extreme temporal challenges, and physiological gating methods must be developed in order to image these organs without motion blur. Commercially available micro-CT imaging devices are equipped with conventional thermionic x-ray sources and have a limited temporal response and are not ideal for in vivo small animal studies. Recent development of a field-emission x-ray source with carbon nanotube (CNT) cathode in our lab presented the opportunity to create a micro-CT device well-suited for in vivo lung and cardiac imaging of murine models for human disease. The goal of this thesis work was to present such a device, to develop and refine protocols which allow high resolution in vivo imaging of free-breathing mice, and to demonstrate the use of this new imaging tool for the study many different disease models. In Chapter 1, I provide background information about x-rays, CT imaging, and small animal micro-CT. In Chapter 2, CNT-based x-ray sources are explained, and details of a micro-focus x-ray tube specialized for micro-CT imaging are presented. In Chapter 3, the first and second generation CNT micro-CT devices are characterized, and successful respiratory- and cardiac-gated live animal imaging on normal, wild-type mice is achieved. In Chapter 4, respiratory-gated imaging of mouse disease models is demonstrated, limitations to the method are discussed, and a new contactless respiration sensor is presented which addresses many of these limitations. In Chapter 5, cardiac-gated imaging of disease models is demonstrated, including studies of aortic calcification, left ventricular hypertrophy, and myocardial infarction. In Chapter 6, several methods for image and system improvement are explored, and radiation

  1. Materials Integration and Doping of Carbon Nanotube-based Logic Circuits

    Science.gov (United States)

    Geier, Michael

    Over the last 20 years, extensive research into the structure and properties of single- walled carbon nanotube (SWCNT) has elucidated many of the exceptional qualities possessed by SWCNTs, including record-setting tensile strength, excellent chemical stability, distinctive optoelectronic features, and outstanding electronic transport characteristics. In order to exploit these remarkable qualities, many application-specific hurdles must be overcome before the material can be implemented in commercial products. For electronic applications, recent advances in sorting SWCNTs by electronic type have enabled significant progress towards SWCNT-based integrated circuits. Despite these advances, demonstrations of SWCNT-based devices with suitable characteristics for large-scale integrated circuits have been limited. The processing methodologies, materials integration, and mechanistic understanding of electronic properties developed in this dissertation have enabled unprecedented scales of SWCNT-based transistor fabrication and integrated circuit demonstrations. Innovative materials selection and processing methods are at the core of this work and these advances have led to transistors with the necessary transport properties required for modern circuit integration. First, extensive collaborations with other research groups allowed for the exploration of SWCNT thin-film transistors (TFTs) using a wide variety of materials and processing methods such as new dielectric materials, hybrid semiconductor materials systems, and solution-based printing of SWCNT TFTs. These materials were integrated into circuit demonstrations such as NOR and NAND logic gates, voltage-controlled ring oscillators, and D-flip-flops using both rigid and flexible substrates. This dissertation explores strategies for implementing complementary SWCNT-based circuits, which were developed by using local metal gate structures that achieve enhancement-mode p-type and n-type SWCNT TFTs with widely separated and

  2. Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF{sub 6} electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Azam, M.A., E-mail: asyadi@utem.edu.my [Carbon Research Technology Research Group, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A. [Carbon Research Technology Research Group, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Kudin, T.I.T. [Ionics Materials & Devices Research Laboratory, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor (Malaysia); Yahya, M.Z.A. [Ionics Materials & Devices Research Laboratory, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor (Malaysia); National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia)

    2015-09-15

    Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF{sub 6} non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g{sup −1}. - Abstract: Carbon nanotubes have been extensively studied because of their wide range of potential application such as in nanoscale electric circuits, textiles, transportation, health, and the environment. Carbon nanotubes feature extraordinary properties, such as electrical conductivities higher than those of copper, hardness and thermal conductivity higher than those of diamond, and strength surpassing that of steel, among others. This research focuses on the fabrication of an energy storage device, namely, an electrochemical capacitor, by using carbon materials, i.e., activated carbon and single-walled carbon nanotubes, of a specific weight ratio as electrode materials. The electrolyte functioning as an ion carrier is 1 M lithium hexafluorophosphate. Variations in the electrochemical performance of the device, including its capacitance, charge/discharge characteristics, and impedance, are reported in this paper. The electrode proposed in this work exhibits a maximum capacitance of 60.97 F g{sup −1} at a scan rate of 1 mV s{sup −1}.

  3. Dynamic response of a carbon nanotube-based rotary nano device with different carbon-hydrogen bonding layout

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Hang [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Cai, Kun, E-mail: caikun1978@163.com [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Wan, Jing [College of Water Resources and Architectural Engineering, Northwest A& F University, Yangling 712100 (China); Gao, Zhaoliang, E-mail: coopcg@163.com [Institute of Soil and Water Conservation, Northwest A& F University, Yangling, 712100 (China); Chen, Zhen [State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Faculty of Vehicle Engineering and Mechanics, Dalian University of Technology, Dalian 116024 (China)

    2016-03-01

    Graphical abstract: - Highlights: • The rotational transmission performance of a rotational transmission system (RTS) with different types of C−H bonding layouts on the edge of motor and rotor is investigated using MD simulation method. • The L–J interaction between covalently bonded hydrogen atoms and sp1 carbon atoms is too weak to support a stable rotational transmission when only the motor or rotor has bonded hydrogen atoms. • When both the motor and rotor have the same C−H bonding layout on their adjacent ends, a stable output rotational speed of rotor can be obtained. • A low input rotational speed (e.g., 100 GHz) would lead to a synchronous rotational transmission if the system has (+0.5H) C−H bonding layout. - Abstract: In a nano rotational transmission system (RTS) which consists of a single walled carbon nanotube (SWCNT) as the motor and a coaxially arranged double walled carbon nanotube (DWCNT) as a bearing, the interaction between the motor and the rotor in bearing, which has great effects on the response of the RTS, is determined by their adjacent edges. Using molecular dynamics (MD) simulation, the interaction is analyzed when the adjacent edges have different carbon-hydrogen (C−H) bonding layouts. In the computational models, the rotor in bearing and the motor with a specific input rotational speed are made from the same armchair SWCNT. Simulation results demonstrate that a perfect rotational transmission could happen when the motor and rotor have the same C−H bonding layout on their adjacent ends. If only half or less of the carbon atoms on the adjacent ends are bonded with hydrogen atoms, the strong attraction between the lower speed (100 GHz) motor and rotor leads to a synchronous rotational transmission. If only the motor or the rotor has C−H bonds on their adjacent ends, no rotational transmission happens due to weak interaction between the bonded hydrogen atoms on one end with the sp{sup 1} bonded carbon atoms on the other

  4. Modification of anisotropic plasma diffusion via auxiliary electrons emitted by a carbon nanotubes-based electron gun in an electron cyclotron resonance ion source.

    Science.gov (United States)

    Malferrari, L; Odorici, F; Veronese, G P; Rizzoli, R; Mascali, D; Celona, L; Gammino, S; Castro, G; Miracoli, R; Serafino, T

    2012-02-01

    The diffusion mechanism in magnetized plasmas is a largely debated issue. A short circuit model was proposed by Simon, assuming fluxes of lost particles along the axial (electrons) and radial (ions) directions which can be compensated, to preserve the quasi-neutrality, by currents flowing throughout the conducting plasma chamber walls. We hereby propose a new method to modify Simon's currents via electrons injected by a carbon nanotubes-based electron gun. We found this improves the source performances, increasing the output current for several charge states. The method is especially sensitive to the pumping frequency. Output currents for given charge states, at different auxiliary electron currents, will be reported in the paper and the influence of the frequency tuning on the compensation mechanism will be discussed.

  5. Comparative study of multi walled carbon nanotubes-based electrodes in micellar media and their application to micellar electrokinetic capillary chromatography.

    Science.gov (United States)

    Chicharro, Manuel; Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio

    2007-12-15

    This work reports on a comparative study of the electrochemical performance of carbon nanotubes-based electrodes in micellar media and their application for amperometric detection in micellar electrokinetic capillary chromatography (MEKC) separations. These electrodes were prepared in two different ways: immobilization of a layer of carbon nanotubes dispersed in polyethylenimine (PEI), ethanol or Nafion onto glassy carbon electrodes or preparation of paste electrodes using mineral oil as binder. Scanning electron microscopy (SEM) was employed for surface morphology characterization while cyclic voltammetry of background electrolyte was used for capacitance estimation. The amperometric responses to hydrogen peroxide, amitrol, diuron and 2,3-dichlorophenol (2,3CP) in the presence and in the absence of sodium dodecylsulphate (SDS) were studied by flow injection analysis (FIA), demonstrating that the electrocatalytic activity, background current and electroanalytical performance were strongly dependent on the electrodes preparation procedure. Glassy carbon electrodes modified with carbon nanotubes dispersed in PEI (GC/(CNT/PEI)) displayed the most adequate performance in micellar media, maintaining good electrocatalytic properties combined with acceptable background currents and resistance to passivation. The advantages of using GC/(CNT/PEI) as detectors in capillary electrophoresis were illustrated for the MEKC separations of phenolic pollutants (phenol, 3-chlorophenol, 2,3-dichlorophenol and 4-nitrophenol) and herbicides (amitrol, asulam, diuron, fenuron, monuron and chlortoluron).

  6. Correlation between permeability and groundwater flow patterns in carbonate rocks

    Science.gov (United States)

    Park, Y.; Lee, J.; Park, Y.; Keehm, Y.

    2011-12-01

    Groundwater flow in carbonate rocks is controlled by many factors such as degree of fracture and pore development, weathering and diagenesis. Among these factors, fracture is main factor and can form main flow path. Also, flow patterns in carbonate area are decided by these factors. This study was performed to understand factors controlling permeability and flow patterns in carbonate area and to evaluate correlation between permeability and flow patterns. Data used in this study were collected from many literatures and these data were analyzed and evaluated using graphic and statistical analysis. In many carbonate areas, branching conduit patterns were dominant. Of these areas, permeability was relatively high in areas where moving distance of flow was short and hydraulic gradient was steep. This work was supported by the Energy Resources R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2009201030001A).

  7. High surface area, high permeability carbon monoliths

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, R.R.; Schroeder, J.L. [Sandia National Labs., Albuquerque, NM (United States). Organic Materials Processing Dept.

    1994-12-31

    The goal of this work is to prepare carbon monoliths having precisely tailored pore size distribution. Prior studies have demonstrated that poly(acrylonitrile) can be processed into a precursor having tailored macropore structure. Since the macropores were preserved during pyrolysis, this synthetic process provided a route to porous carbon having macropores with size =0.1 to 10{mu}m. No micropores of size <2 nm could be detected in the carbon, however, by nitrogen adsorption. In the present work, the authors have processed a different polymer, poly(vinylidene chloride) into a macroporous precursor, Pyrolysis produced carbon monoliths having macropores derived from the polymer precursor as well as extensive microporosity produced during the pyrolysis of the polymer. One of these carbons had BET surface area of 1,050 m{sup 2}/g and about 1.2 cc/g total pore volume, with about 1/3 of the total pore volume in micropores and the remainder in 1{mu}m macropores. No mesopores in the intermediate size range could be detected by nitrogen adsorption. Carbon materials having high surface area as well as micron size pores have potential applications as electrodes for double layer supercapacitors containing liquid electrolyte, or as efficient media for performing chemical separations.

  8. Single-walled and multi-walled carbon nanotubes based drug delivery system: Cancer therapy: A review

    OpenAIRE

    Dineshkumar, B.; Krishnakumar, K; A R Bhatt; D Paul; Cherian, J; John, A.; S. Suresh

    2015-01-01

    Carbon nanotubes (CNTs) are advanced nano-carrier for delivery of drugs especially anti-cancer drugs. In the field of CNT-based drug delivery system, both single-walled carbon nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs) can be used for targeting anticancer drugs in tissues and organs, where the high therapeutic effect is necessary. Benefits of the carbon nanotubes (CNTs) in drug delivery systems are; avoiding solvent usage and reducing the side effects. Therefore, the present revie...

  9. Single-walled and multi-walled carbon nanotubes based drug delivery system: Cancer therapy: A review

    Directory of Open Access Journals (Sweden)

    B Dineshkumar

    2015-01-01

    Full Text Available Carbon nanotubes (CNTs are advanced nano-carrier for delivery of drugs especially anti-cancer drugs. In the field of CNT-based drug delivery system, both single-walled carbon nanotubes (SWCNTs and multi-walled nanotubes (MWCNTs can be used for targeting anticancer drugs in tissues and organs, where the high therapeutic effect is necessary. Benefits of the carbon nanotubes (CNTs in drug delivery systems are; avoiding solvent usage and reducing the side effects. Therefore, the present review article described about achievement of SWCNTs and MWCNTs to deliver the anticancer drugs with different cancerous cell lines.

  10. Single-walled and multi-walled carbon nanotubes based drug delivery system: Cancer therapy: A review.

    Science.gov (United States)

    Dineshkumar, B; Krishnakumar, K; Bhatt, A R; Paul, D; Cherian, J; John, A; Suresh, S

    2015-01-01

    Carbon nanotubes (CNTs) are advanced nano-carrier for delivery of drugs especially anti-cancer drugs. In the field of CNT-based drug delivery system, both single-walled carbon nanotubes (SWCNTs) and multi-walled nanotubes (MWCNTs) can be used for targeting anticancer drugs in tissues and organs, where the high therapeutic effect is necessary. Benefits of the carbon nanotubes (CNTs) in drug delivery systems are; avoiding solvent usage and reducing the side effects. Therefore, the present review article described about achievement of SWCNTs and MWCNTs to deliver the anticancer drugs with different cancerous cell lines.

  11. Design and adaptation of miniaturized electrochemical devices integrating carbon nanotube-based sensors to commercial CE equipment.

    Science.gov (United States)

    Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Angeles Lorenzo, M; Zapardiel, Antonio; Chicharro, Manuel

    2009-10-01

    The design of new electrochemical devices integrating carbon nanotube sensors and their adaptation to commercial CE equipments are described. One of these designs was made for using commercial screen-printed electrodes, whereas the second was projected for coupling commercial glassy carbon electrodes. The electrochemical characterization of these devices revealed that their hydrodynamic behaviour is strongly influenced by the electrode modification with multi-wall carbon nanotubes that provided faster and/or more sensitive signals. The analytical applicability of these devices was illustrated for the CZE separation of chlorinated phenols and the MEKC separation of endocrine disruptors, where the use of carbon nanotube sensors has proved to be advantageous when compared with unmodified ones, with good electrocatalytic properties combined with acceptable background currents and a remarkable resistance to passivation.

  12. On the Strength of the Carbon Nanotube-Based Space Elevator Cable: From Nano- to Mega-Mechanics

    OpenAIRE

    Pugno, Nicola M.

    2006-01-01

    In this paper different deterministic and statistical models, based on new quantized theories proposed by the author, are presented to estimate the strength of a real, thus defective, space elevator cable. The cable, of ~100 megameters in length, is composed by carbon nanotubes, ~100 nanometers long: thus, its design involves from the nano- to the mega-mechanics. The predicted strengths are extensively compared with the experiments and the atomistic simulations on carbon nanotubes available i...

  13. Effects of initial stress on transverse wave propagation in carbon nanotubes based on Timoshenko laminated beam models

    Science.gov (United States)

    Cai, H.; Wang, X.

    2006-01-01

    Based on Timoshenko laminated beam models, this paper investigates the influence of initial stress on the vibration and transverse wave propagation in individual multi-wall carbon nanotubes (MWNTs) under ultrahigh frequency (above 1 THz), in which the initial stress in the MWNTs can occur due to thermal or lattice mismatch between different materials. Considering van der Waals force interaction between two adjacent tubes and effects of rotary inertia and shear deformation, results show that the initial stress in individual multi-wall carbon nanotubes not only affects the number of transverse wave speeds and the magnitude of transverse wave speeds, but also terahertz critical frequencies at which the number of wave speeds changes. When the initial stress in individual multi-wall carbon nanotubes is the compressive stress, transverse wave speeds decrease and the vibration amplitude ratio of two adjacent tubes increases. When the initial stress in individual multi-wall carbon nanotubes is the tensile stress, transverse wave speeds increase and the vibration amplitude ratio of two adjacent tubes decreases. The investigation of the effects of initial stress on transverse wave propagation in carbon nanotubes may be used as a useful reference for the application and the design of nanoelectronic and nanodrive devices, nano-oscillators, and nanosensors, in which carbon nanotubes act as basic elements.

  14. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals.

    Science.gov (United States)

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf

    2014-09-19

    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  15. Determination of the effective Young's modulus of vertically aligned carbon nanotube arrays: a simple nanotube-based varactor.

    Science.gov (United States)

    Olofsson, Niklas; Ek-Weis, Johan; Eriksson, Anders; Idda, Tonio; Campbell, Eleanor E B

    2009-09-23

    The electromechanical properties of arrays of vertically aligned multiwalled carbon nanotubes were studied in a parallel plate capacitor geometry. The electrostatic actuation was visualized using both optical microscopy and scanning electron microscopy, and highly reproducible behaviour was achieved for actuation voltages below the pull-in voltage. The walls of vertically aligned carbon nanotubes behave as solid cohesive units. The effective Young's modulus for the carbon nanotube arrays was determined by comparing the actuation results with the results of electrostatic simulations and was found to be exceptionally low, of the order of 1-10 MPa. The capacitance change and Q-factor were determined by measuring the frequency dependence of the radio-frequency transmission. Capacitance changes of over 20% and Q-factors in the range 100-10 were achieved for a frequency range of 0.2-1.5 GHz.

  16. Carbon Nanotube-Based Supercapacitors with Excellent ac Line Filtering and Rate Capability via Improved Interfacial Impedance.

    Science.gov (United States)

    Rangom, Yverick; Tang, Xiaowu Shirley; Nazar, Linda F

    2015-07-28

    We report the fabrication of high-performance, self-standing composite sp(2)-carbon supercapacitor electrodes using single-walled carbon nanotubes (CNTs) as conductive binder. The 3-D mesoporous mesh architecture of CNT-based composite electrodes grants unimpaired ionic transport throughout relatively thick films and allows superior performance compared to graphene-based devices at an ac line frequency of 120 Hz. Metrics of 601 μF/cm(2) with a -81° phase angle and a rate capability (RC) time constant of 199 μs are obtained for thin carbon films. The free-standing carbon films were obtained from a chlorosulfonic acid dispersion and interfaced to stainless steel current collectors with various surface treatments. CNT electrodes were able to cycle at 200 V/s and beyond, still showing a characteristic parallelepipedic cyclic votammetry shape at 1 kV/s. Current densities are measured in excess of 6400 A/g, and the electrodes retain more than 98% capacity after 1 million cycles. These promising results are attributed to a reduction of series resistance in the film through the CNT conductive network and especially to the surface treatment of the stainless steel current collector.

  17. Outstanding field emission properties of wet-processed titanium dioxide coated carbon nanotube based field emission devices

    Science.gov (United States)

    Xu, Jinzhuo; Xu, Peng; Ou-Yang, Wei; Chen, Xiaohong; Guo, Pingsheng; Li, Jun; Piao, Xianqing; Wang, Miao; Sun, Zhuo

    2015-02-01

    Field emission devices using a wet-processed composite cathode of carbon nanotube films coated with titanium dioxide exhibit outstanding field emission characteristics, including ultralow turn on field of 0.383 V μm-1 and threshold field of 0.657 V μm-1 corresponding with a very high field enhancement factor of 20 000, exceptional current stability, and excellent emission uniformity. The improved field emission properties are attributed to the enhanced edge effect simultaneously with the reduced screening effect, and the lowered work function of the composite cathode. In addition, the highly stable electron emission is found due to the presence of titanium dioxide nanoparticles on the carbon nanotubes, which prohibits the cathode from the influence of ions and free radical created in the emission process as well as residual oxygen gas in the device. The high-performance solution-processed composite cathode demonstrates great potential application in vacuum electronic devices.

  18. Single walled carbon nanotube-based electrical biosensor for the label-free detection of pathogenic bacteria

    DEFF Research Database (Denmark)

    Yoo, S. M.; Baek, Y. K.; Shin, S.

    2016-01-01

    We herein describe the development of a single-walled carbon nanotube (SWNT)-based electrical biosensor consisting of a two-terminal resistor, and report its use for the specific, label-free detection of pathogenic bacteria via changes in conductance. The ability of this biosensor to recognize....... This SWNT-based electrical biosensor will prove useful for the development of highly sensitive and specific handheld pathogen detectors....

  19. Design of carbon nanotube-based gas-diffusion cathode for O{sub 2} reduction by multicopper oxidases

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Carolin; Adkins, Emily R.; Atanassov, Plamen [University of New Mexico, Center for Emerging Energy Technologies, Albuquerque, NM (United States); Ramasamy, Ramaraja P. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States); Nano-Electrochemistry Laboratory, Faculty of Engineering, University of Georgia, Athens, GA (United States); Luckarift, Heather R.; Johnson, Glenn R. [Microbiology and Applied Biochemistry, Airbase Sciences, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States)

    2012-01-15

    Multicopper oxidases, such as laccase or bilirubin oxidase, are known to reduce molecular oxygen at very high redox potentials, which makes them attractive biocatalysts for enzymatic cathodes in biological fuel cells. By designing an enzymatic gas-diffusion electrode, molecular oxygen can be supplied through the gaseous phase, avoiding solubility and diffusion limitations typically associated with liquid electrolytes. In doing so, the current density of enzymatic cathodes can theoretically be enhanced. This publication presents a material study of carbon/Teflon composites that aim to optimize the functionality of the gas-diffusion and catalytic layers for application in enzymatic systems. The modification of the catalytic layer with multiwalled carbon nanotubes, for example, creates the basis for stronger {pi}-{pi} stacking interactions through tethered enzymatic linkers, such as pyrenes or perylene derivates. Cyclic voltammograms show the effective direct electron contact of laccase with carbon nanotube-modified electrodes via tethered crosslinking molecules as a model system. The polarization behavior of laccase-modified gas-diffusion electrodes reveals open-circuit potentials of +550 mV (versus Ag/AgCl) and current densities approaching 0.5 mA cm{sup 2} (at zero potential) in air-breathing mode. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Implementation of a safe-by-design approach in the development of new open pilot lines for the manufacture of carbon nanotube-based nano-enabled products

    Science.gov (United States)

    López de Ipiña, Jesús M.; Hernan, Angel; Cenigaonaindia, Xabier; Insunza, Mario; Florez, Sonia; Seddon, Richard; Vavouliotis, Antonios; Kostopoulos, Vasilios; Latko, Paulina; Durałek, Paweł; Kchit, Nadir

    2017-06-01

    The project PLATFORM (H2020, GA 646307) aims to develop three new pilot lines (PPLs) for the manufacture of carbon nanotube-based nano-enabled products (buckypapers, treated prepregs, doped veils), for the European aeronautics and automotive industries (a Technology Readiness Level 6 - TRL6 - is expected at the end of the project). The Machinery Directive 2006/42/EC (MD) - transposed into the respective national legislations - is the European regulatory framework for the design and construction of new machinery, as the future PPLs. PPLs are not required to comply with the provisions of the MD until they are put into service - expected in 2020, after project completion - but then, the MD will be fully applicable. In this regulatory context, the project PLATFORM is aligning the design of the PPLs according to the MD requirements, in order to facilitate the CE marking in 2020 (TRL9) and avoid potential economic costs associated with future re-adaptations or modifications needed to ensure compliance with the MD. This paper discusses the methodological approach followed by the project PLATFORM to integrate all the nanosafety aspects in the design of the PPLs, in order to achieve safe designs in conformity with the relevant Essential Health and Safety Requirements (EHSRs) of the MD. Since machinery must be designed and constructed taking into account the results of the risk assessment (RA), this paper describes the systematic and iterative approach for RA and risk reduction followed to eliminate hazards as far practicable and to adequately reduce risks by the implementation of protective measures. This process has been guided by the harmonized standards EN ISO 12100 and EN ISO 14123, taking the relevant phases of life cycle, expected uses and operation modes of the PPLs into account. A specific tool to guide the safe design of the PPLs and facilitate the RA process has also been produced by the project (PLATFORM - SbD toolkit).

  1. Rayleigh-Ritz Vibrational Analysis of Multiwalled Carbon Nanotubes Based on the Nonlocal Flügge Shell Theory

    Directory of Open Access Journals (Sweden)

    H. Rouhi

    2015-01-01

    Full Text Available A nonlocal elastic shell model considering the small scale effects is developed to study the free vibrations of multiwalled carbon nanotubes subject to different types of boundary conditions. Based on the nonlocal elasticity and the Flügge shell theory, the governing equations are derived which include the interaction of van der Waals forces between adjacent and nonadjacent layers. To analytically solve the problem, the Rayleigh-Ritz method is employed. In the present analysis, different combinations of layerwise boundary conditions are taken into account. Some new intertube resonant frequencies and the associated noncoaxial vibrational modes are identified owing to incorporating circumferential modes into the shell model.

  2. Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory.

    Science.gov (United States)

    Fakhrabadi, Mir Masoud Seyyed; Rastgoo, Abbas; Ahmadian, Mohammad Taghi

    2013-01-01

    The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes.

  3. A Carbon Nanotube-based NEMS Parametric Amplifier for Enhanced Radio Wave Detection and Electronic Signal Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Aleman, B J; Sussman, A; Zettl, A [Physics Department, University of California, Berkeley, CA 94720 (United States); Mickelson, W, E-mail: azettl@berkeley.edu [Center of Integrated Nanomechanical Systems, University of California, Berkeley, CA 94720 (United States)

    2011-07-20

    We propose a scheme for a parametric amplifier based on a single suspended carbon nanotube field-emitter. This novel electromechanical nanotube device acts as a phase-sensitive, variable-gain, band-pass-filtering amplifier for electronic signal processing and, at the same time, can operate as a variable-sensitivity, tuneable detector and transducer of radio frequency electromagnetic waves. The amplifier can exhibit infinite gain at pumping voltages much less than 10 Volts. Additionally, the amplifier's low overhead power consumption (10-1000 nW) make it exceptionally attractive for ultra-low-power applications.

  4. Vibrational behavior of single-walled carbon nanotubes based on cylindrical shell model using wave propagation approach

    Directory of Open Access Journals (Sweden)

    Muzamal Hussain

    2017-04-01

    Full Text Available The vibration analysis, based on the Donnell thin shell theory, of single-walled carbon nanotubes (SWCNTs has been investigated. The wave propagation approach in standard eigenvalue form has been employed in order to derive the characteristic frequency equation describing the natural frequencies of vibration in SWCNTs. The complex exponential functions, with the axial modal numbers that depend on the boundary conditions stated at edges of a carbon nanotube, have been used to compute the axial modal dependence. In our new investigations, the vibration frequency spectra are obtained and calculated for various physical parameters like length-to-diameter ratios for armchair and zigzag SWCNTs for different modes and in-plane rigidity and mass density per unit lateral area for armchair and zigzag SWCNTs on the vibration frequencies. The computer software MATLAB is used in order to compute these frequencies of the SWCNTs. The results obtained from wave propagation method are found to be in satisfactory agreement with that obtained through the previously known numerical molecular dynamics simulations.

  5. Stable and sensitive flow-through monitoring of phenol using a carbon nanotube based screen printed biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Alarcon, G; Guix, M; Ambrosi, A; Merkoci, A [Nanobioelectronics and Biosensors Group, Catalan Institute of Nanotechnology, Campus UAB, 08193 Bellaterra, Barcelona, Catalonia (Spain); Ramirez Silva, M T [Departamento de Quimica, Universidad Autonoma Metropolitana Iztapalapa, 09340 Mexico Distrito Federal (Mexico); Palomar Pardave, M E, E-mail: arben.merkoci.icn@uab.es [Departamento de Materiales, Universidad Autonoma Metropolitana, Azcapotzalco, 02200 Mexico Distrito Federal (Mexico)

    2010-06-18

    A stable and sensitive biosensor for phenol detection based on a screen printed electrode modified with tyrosinase, multiwall carbon nanotubes and glutaraldehyde is designed and applied in a flow injection analytical system. The proposed carbon nanotube matrix is easy to prepare and ensures a very good entrapment environment for the enzyme, being simpler and cheaper than other reported strategies. In addition, the proposed matrix allows for a very fast operation of the enzyme, that leads to a response time of 15 s. Several parameters such as the working potential, pH of the measuring solution, biosensor response time, detection limit, linear range of response and sensitivity are studied. The obtained detection limit for phenol was 0.14 x 10{sup -6} M. The biosensor keeps its activity during continuous FIA measurements at room temperature, showing a stable response (RSD 5%) within a two week working period at room temperature. The developed biosensor is being applied for phenol detection in seawater samples and seems to be a promising alternative for automatic control of seawater contamination. The developed detection system can be extended to other enzyme biosensors with interest for several other applications.

  6. A carbon nanotube-based high-sensitivity electrochemical immunosensor for rapid and portable detection of clenbuterol.

    Science.gov (United States)

    Liu, Gang; Chen, Haode; Peng, Hongzhen; Song, Shiping; Gao, Jimin; Lu, Jianxin; Ding, Min; Li, Lanying; Ren, Shuzhen; Zou, Ziying; Fan, Chunhai

    2011-10-15

    Carbon nanotubes have shown their unique advantages of mechanical, chemical and electronic properties in bioanalysis. We herein report a new method to efficiently and reproducibly prepare multi-walled carbon nanotubes (MWNTs)-protein sensing layers for electrochemical immunosensors. This method employs centrifugation to prepare a conjugate of MWNTs and goat anti mouse-immunoglobulin G (IgG) (secondary antibody). The conjugates were then deposited on screen-printed electrodes to form a nanostructured layer (MWNT-I layer). CLB monoclonal antibody was assembled through its binding to the secondary antibody. The MWNT-I layer-based electrodes were used for rapid and sensitive amperometric immunosensing detection of clenbuterol (CLB) in swine urine samples. Horseradish peroxidase-coupled CLB (CLB-HRP) competed with free CLB in the samples to bind the monoclonal antibody. It has shown significantly higher sensitivity and better reproducibility than the chemical conjugation method. This MWNT-based immunosensor is highly sensitive, leading to a limit of detection of 0.1 ng/mL within a rapid assay time of 16 min. Its sensitivity is at least 1 order of magnitude higher than that of a normal immunosensor (without MWNTs). The sensing device is portable with disposable screen-printed electrode, satisfactorily meeting the requirements for field detection of food security-related species.

  7. Outstanding field emission properties of wet-processed titanium dioxide coated carbon nanotube based field emission devices

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jinzhuo; Ou-Yang, Wei, E-mail: ouyangwei@phy.ecnu.edu.cn; Chen, Xiaohong; Guo, Pingsheng; Piao, Xianqing; Sun, Zhuo [Engineering Research Center for Nanophotonics and Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062 (China); Xu, Peng; Wang, Miao [Department of Physics, Zhejiang University, 38 ZheDa Road, Hangzhou 310027 (China); Li, Jun [Department of Electronic Science and Technology, Tongji University, 4800 Caoan Road, Shanghai 201804 (China)

    2015-02-16

    Field emission devices using a wet-processed composite cathode of carbon nanotube films coated with titanium dioxide exhibit outstanding field emission characteristics, including ultralow turn on field of 0.383 V μm{sup −1} and threshold field of 0.657 V μm{sup −1} corresponding with a very high field enhancement factor of 20 000, exceptional current stability, and excellent emission uniformity. The improved field emission properties are attributed to the enhanced edge effect simultaneously with the reduced screening effect, and the lowered work function of the composite cathode. In addition, the highly stable electron emission is found due to the presence of titanium dioxide nanoparticles on the carbon nanotubes, which prohibits the cathode from the influence of ions and free radical created in the emission process as well as residual oxygen gas in the device. The high-performance solution-processed composite cathode demonstrates great potential application in vacuum electronic devices.

  8. Wave dispersion in viscoelastic single walled carbon nanotubes based on the nonlocal strain gradient Timoshenko beam model

    Science.gov (United States)

    Tang, Yugang; Liu, Ying; Zhao, Dong

    2017-03-01

    Based on the nonlocal strain gradient theory and Timoshenko beam model, the properties of wave propagation in a viscoelastic single-walled carbon nanotube (SWCNT) are investigated. The characteristic equations for flexural and shear waves in visco-SWCNTs are established. The influence of the tube size on the wave dispersion is clarified. For a low damping coefficient, threshold diameter for shear wave (SW) is observed, below which the phase velocity of SW is equal to zero, whilst flexural wave (FW) always exists. For a high damping coefficient, SW is absolutely constrained, and blocking diameter for FW is observed, above which the wave propagation is blocked. The effects of the wave number, nonlocal and strain gradient length scale parameters on the threshold and blocking diameters are discussed in detail.

  9. Imperfection Sensitivity of Nonlinear Vibration of Curved Single-Walled Carbon Nanotubes Based on Nonlocal Timoshenko Beam Theory

    Directory of Open Access Journals (Sweden)

    Iman Eshraghi

    2016-09-01

    Full Text Available Imperfection sensitivity of large amplitude vibration of curved single-walled carbon nanotubes (SWCNTs is considered in this study. The SWCNT is modeled as a Timoshenko nano-beam and its curved shape is included as an initial geometric imperfection term in the displacement field. Geometric nonlinearities of von Kármán type and nonlocal elasticity theory of Eringen are employed to derive governing equations of motion. Spatial discretization of governing equations and associated boundary conditions is performed using differential quadrature (DQ method and the corresponding nonlinear eigenvalue problem is iteratively solved. Effects of amplitude and location of the geometric imperfection, and the nonlocal small-scale parameter on the nonlinear frequency for various boundary conditions are investigated. The results show that the geometric imperfection and non-locality play a significant role in the nonlinear vibration characteristics of curved SWCNTs.

  10. A styrene-butadiene rubber (SBR)/carbon nanotube-based smart force sensor for automotive tire deformation monitoring

    Science.gov (United States)

    Cho, Min-Young; Kim, Ji-Sik; Lee, Ho-Geun; Choi, Seung-Bok; Kim, Gi-Woo

    2016-04-01

    This paper provides a preliminary study on the piezoresistive effect of a styrene-butadiene Rubber (SBR), one of the main ingredients of automotive tire, dispersed with carbon nanotubes (CNTs) to explore its feasibility as a force sensor embedded in automotive tires. Typically, the application of CNTs has been successfully applied to the mechanical sensing technology such as a stress/strain and impact sensor. In this study, the potential of using the SBR/CNT as a force sensor for monitoring automotive tire deformation is evaluated for the first time. Experimental results show that the electrical resistance of the SBR/CNT composite changes in response to the sinusoidal loading, as well as static compressive load. These piezoresistive responses of the SBR/CNT composite will be used for sensing the tire deformation caused by the vehicle loading or cracks of tires.

  11. Targeted therapy of SMMC-7721 liver cancer in vitro and in vivo with carbon nanotubes based drug delivery system.

    Science.gov (United States)

    Ji, Zongfei; Lin, Gaofeng; Lu, Qinghua; Meng, Lingjie; Shen, Xizhong; Dong, Ling; Fu, Chuanlong; Zhang, Xiaoke

    2012-01-01

    A new type of drug delivery system (DDS) involved chitosan (CHI) modified single walled carbon nanotubes (SWNTs) for controllable loading/release of anti-cancer doxorubicin (DOX) was constructed. CHI was non-covalently wrapped around SWNTs, imparting water-solubility and biocompatibility to the nanotubes. Folic acid (FA) was also bounded to the outer CHI layer to realize selective killing of tumor cells. The targeting DDS could effectively kill the HCC SMMC-7721 cell lines and depress the growth of liver cancer in nude mice, showing superior pharmaceutical efficiency to free DOX. The results of the blood routine and serum biochemical parameters, combined with the histological examinations of vital organs, demonstrating that the targeting DDS had negligible in vivo toxicity. Thus, this DDS is promising for high treatment efficacy and low side effects for future cancer therapy.

  12. Design and characterization of a carbon-nanotube-based micro-focus x-ray tube for small animal imaging

    Science.gov (United States)

    Sultana, Shabana; Calderón-Colón, Xiomara; Cao, Guohua; Zhou, Otto; Lu, Jianping

    2010-04-01

    We report the progress in development of carbon nanotube (CNT) field emission micro-focus x-ray tubes for dynamic small animal imaging with high spatial and temporal resolution. Extensive electron optics simulations were performed to study the focusing structure and optimize the tube design. 3D finite element analysis was used for modeling and simulating electron beam optics. A simple and intuitive model is developed to model the field emission properties of CNT cathodes. The dependence of focus spot size and the anode current on the gate extracting voltage, the focusing voltages, the gate mesh geometry, and other geometric parameters were studied. Several tubes were built according to the optimal design. The experimentally measured focus spot size and its dependence on the focus voltages were found to be in quantitative agreement with simulations.

  13. Carbon Nanotube-based Nanohybrid Materials as Counter Electrode for Highly Efficient Dye-sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-Soo; Sim, Eun-Ju; Dao, Van-Duong; Choi, Ho-Suk [Chungnam National University, Daejeon (Korea, Republic of)

    2016-04-15

    In this study, we present an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic PtAu nanoparticles (NPs) on a multi-walled carbon nanotube (MWNT)-coated layer through dry plasma reduction. The NPs are stably and uniformly immobilized on the surface of MWNTs and the nanohybrid materials are applied to counter electrode (CE) of dye-sensitized solar cells (DSCs). The electrochemical properties of CEs are examined through cyclic voltammogram, electrochemical impedance spectroscopy, and Tafel measurements. As a result, both electrochemical catalytic activity and electrical conductivity are highest for PtAu/MWNT electrode. The DSC employing PtAu/MWNT CE exhibits power conversion efficiency of 7.9%. The efficiency is better than those of devices with MWNT (2.6%), AuNP/MWNT (2.7%) and PtNP/MWNT (7.5%) CEs.

  14. Conducting polymer functionalized single-walled carbon nanotube based chemiresistive biosensor for the detection of human cardiac myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Puri, Nidhi [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Department of Physics, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi 110025 (India); Niazi, Asad [Department of Physics, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi 110025 (India); Biradar, Ashok M.; Rajesh, E-mail: rajesh-csir@yahoo.com, E-mail: adani@engr.ucr.edu [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Mulchandani, Ashok, E-mail: rajesh-csir@yahoo.com, E-mail: adani@engr.ucr.edu [Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521 (United States)

    2014-10-13

    We report the fabrication of a single-walled carbon nanotube (SWNT) based ultrasensitive label-free chemiresistive biosensor for the detection of human cardiac biomarker, myoglobin (Ag-cMb). Poly(pyrrole-co-pyrrolepropylic acid) with pendant carboxyl groups was electrochemically deposited on electrophoretically aligned SWNT channel, as a conducting linker, for biomolecular immobilization of highly specific cardiac myoglobin antibody. The device was characterized by scanning electron microscopy, source-drain current-voltage (I-V), and charge-transfer characteristic studies. The device exhibited a linear response with a change in conductance in SWNT channel towards the target, Ag-cMb, over the concentration range of 1.0 to 1000 ng ml{sup −1} with a sensitivity of ∼118% per decade with high specificity.

  15. Fabrication of platinum-decorated single-walled carbon nanotube based hydrogen sensors by aerosol jet printing.

    Science.gov (United States)

    Liu, Rui; Ding, Haiyan; Lin, Jian; Shen, Fangping; Cui, Zheng; Zhang, Ting

    2012-12-21

    The coffee ring effect is reduced effectively and a hydrogen sensor with platinum-decorated single-walled carbon nanotubes (SWCNTs) is prepared by aerosol jet printing (AJP) technology. The stable aqueous solution of platinum functional SWCNTs is prepared by a series of chemical and physical processes and the electrode array is formed by micro-fabrication technology. The AJP process is also researched in detail including the number of printing passes and the printing distance between electrodes. Then, the functional SWCNT aqueous solution is printed on the electrode array and the response of this sensor to the hydrogen is measured carefully. The results show that a functional SWCNT sensor has excellent sensing properties toward hydrogen.

  16. Effective Permeability Change in Wellbore Cement with Carbon Dioxide Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Jung, Hun Bok; Martin, Paul F.; McGrail, B. Peter

    2011-11-01

    -sized calcite on the outside surface of cement, which resulted in the decrease in BJH pore volume and BET surface area. Cement carbonation and pore structure change are significantly dependent on pressure and temperature conditions as well as the phase of CO{sub 2}, which controls the balance between precipitation and dissolution in cement matrix. Geochemical modeling result suggests that ratio of solid (cement)-to-solution (carbonated water) has a significant effect on cement carbonation, thus the cement-CO{sub 2} reaction experiment needs to be conducted under realistic conditions representing the in-situ wellbore environment of carbon sequestration field site. Total porosity and air permeability for a duplicate cement column with water-to-cement ratio of 0.38 measured after oven-drying by Core Laboratories using Boyle's Law technique and steady-state method were 31% and 0.576 mD. A novel method to measure the effective liquid permeability of a cement column using X-ray micro-tomography images after injection of pressurized KI (potassium iodide) is under development by PNNL. Preliminary results indicate the permeability of a cement column with water-to-cement ratio of 0.38 is 4-8 mD. PNNL will apply the method to understand the effective permeability change of Portland cement by CO{sub 2}(g) reaction under a variety of pressure and temperature conditions to develop a more reliable well-bore leakage risk model.

  17. Mechanical, electrical, and thermal expansion properties of carbon nanotube-based silver and silver-palladium alloy composites

    Institute of Scientific and Technical Information of China (English)

    Hemant Pal; Vimal Sharma

    2014-01-01

    The mechanical, electrical, and thermal expansion properties of carbon nanotube (CNT)-based silver and silver–palladium (10:1, w/w) alloy nanocomposites are reported. To tailor the properties of silver, CNTs were incorporated into a silver matrix by a modified mo-lecular level-mixing process. CNTs interact weakly with silver because of their non-reactive nature and lack of mutual solubility. Therefore, palladium was utilized as an alloying element to improve interfacial adhesion. Comparative microstructural characterizations and property evaluations of the nanocomposites were performed. The structural characterizations revealed that decorated type-CNTs were dispersed, em-bedded, and anchored into the silver matrix. The experimental results indicated that the modification of the silver and silver–palladium nanocomposite with CNT resulted in increases in the hardness and Young’s modulus along with concomitant decreases in the electrical con-ductivity and the coefficient of thermal expansion (CTE). The hardness and Young’s modulus of the nanocomposites were increased by 30%-40% whereas the CTE was decreased to 50%-60% of the CTE of silver. The significantly improved CTE and the mechanical proper-ties of the CNT-reinforced silver and silver–palladium nanocomposites are correlated with the intriguing properties of CNTs and with good interfacial adhesion between the CNTs and silver as a result of the fabrication process and the contact action of palladium as an alloying ele-ment.

  18. Single-walled carbon nanotubes based chemiresistive genosensor for label-free detection of human rheumatic heart disease

    Science.gov (United States)

    Singh, Swati; Kumar, Ashok; Khare, Shashi; Mulchandani, Ashok; Rajesh

    2014-11-01

    A specific and ultrasensitive, label free single-walled carbon nanotubes (SWNTs) based chemiresistive genosensor was fabricated for the early detection of Streptococcus pyogenes infection in human causing rheumatic heart disease. The mga gene of S. pyogenes specific 24 mer ssDNA probe was covalently immobilized on SWNT through a molecular bilinker, 1-pyrenemethylamine, using carbodiimide coupling reaction. The sensor was characterized by the current-voltage (I-V) characteristic curve and scanning electron microscopy. The sensing performance of the sensor was studied with respect to changes in conductance in SWNT channel based on hybridization of the target S. pyogenes single stranded genomic DNA (ssG-DNA) to its complementary 24 mer ssDNA probe. The sensor shows negligible response to non-complementary Staphylococcus aureus ssG-DNA, confirming the specificity of the sensor only with S. pyogenes. The genosensor exhibited a linear response to S. pyogenes G-DNA from 1 to1000 ng ml-1 with a limit of detection of 0.16 ng ml-1.

  19. A novel multi-walled carbon nanotube-based antibody conjugate for quantitative and semi-quantitative lateral flow assays.

    Science.gov (United States)

    Sun, Wenjuan; Hu, Xiaolong; Liu, Jia; Zhang, Yurong; Lu, Jianzhong; Zeng, Libo

    2017-10-01

    In this study, the multi-walled carbon nanotubes (MWCNTs) were applied in lateral flow strips (LFS) for semi-quantitative and quantitative assays. Firstly, the solubility of MWCNTs was improved using various surfactants to enhance their biocompatibility for practical application. The dispersed MWCNTs were conjugated with the methamphetamine (MET) antibody in a non-covalent manner and then manufactured into the LFS for the quantitative detection of MET. The MWCNTs-based lateral flow assay (MWCNTs-LFA) exhibited an excellent linear relationship between the values of test line and MET when its concentration ranges from 62.5 to 1500 ng/mL. The sensitivity of the LFS was evaluated by conjugating MWCNTs with HCG antibody and the MWCNTs conjugated method is 10 times more sensitive than the one conjugated with classical colloidal gold nanoparticles. Taken together, our data demonstrate that MWCNTs-LFA is a more sensitive and reliable assay for semi-quantitative and quantitative detection which can be used in forensic analysis.

  20. Single-walled carbon nanotubes based chemiresistive genosensor for label-free detection of human rheumatic heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Swati; Kumar, Ashok, E-mail: rajesh-csir@yahoo.com, E-mail: ashokigib@rediffmail.com [CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi 110007 (India); Academy of Scientific and Innovative Research (AcSIR), New Delhi (India); Khare, Shashi [National Centre for Disease Control, Sham Nath Marg, Delhi 110054 (India); Mulchandani, Ashok [Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521 (United States); Rajesh, E-mail: rajesh-csir@yahoo.com, E-mail: ashokigib@rediffmail.com [CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2014-11-24

    A specific and ultrasensitive, label free single-walled carbon nanotubes (SWNTs) based chemiresistive genosensor was fabricated for the early detection of Streptococcus pyogenes infection in human causing rheumatic heart disease. The mga gene of S. pyogenes specific 24 mer ssDNA probe was covalently immobilized on SWNT through a molecular bilinker, 1-pyrenemethylamine, using carbodiimide coupling reaction. The sensor was characterized by the current-voltage (I-V) characteristic curve and scanning electron microscopy. The sensing performance of the sensor was studied with respect to changes in conductance in SWNT channel based on hybridization of the target S. pyogenes single stranded genomic DNA (ssG-DNA) to its complementary 24 mer ssDNA probe. The sensor shows negligible response to non-complementary Staphylococcus aureus ssG-DNA, confirming the specificity of the sensor only with S. pyogenes. The genosensor exhibited a linear response to S. pyogenes G-DNA from 1 to1000 ng ml{sup −1} with a limit of detection of 0.16 ng ml{sup −1}.

  1. Heating-Rate-Triggered Carbon-Nanotube-based 3-Dimensional Conducting Networks for a Highly Sensitive Noncontact Sensing Device

    KAUST Repository

    Tai, Yanlong

    2016-01-28

    Recently, flexible and transparent conductive films (TCFs) are drawing more attention for their central role in future applications of flexible electronics. Here, we report the controllable fabrication of TCFs for moisture-sensing applications based on heating-rate-triggered, 3-dimensional porous conducting networks through drop casting lithography of single-walled carbon nanotube (SWCNT)/poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS) ink. How ink formula and baking conditions influence the self-assembled microstructure of the TCFs is discussed. The sensor presents high-performance properties, including a reasonable sheet resistance (2.1 kohm/sq), a high visible-range transmittance (>69%, PET = 90%), and good stability when subjected to cyclic loading (>1000 cycles, better than indium tin oxide film) during processing, when formulation parameters are well optimized (weight ratio of SWCNT to PEDOT:PSS: 1:0.5, SWCNT concentration: 0.3 mg/ml, and heating rate: 36 °C/minute). Moreover, the benefits of these kinds of TCFs were verified through a fully transparent, highly sensitive, rapid response, noncontact moisture-sensing device (5 × 5 sensing pixels).

  2. A fully roll-to-roll gravure-printed carbon nanotube-based active matrix for multi-touch sensors

    Science.gov (United States)

    Lee, Wookyu; Koo, Hyunmo; Sun, Junfeng; Noh, Jinsoo; Kwon, Kye-Si; Yeom, Chiseon; Choi, Younchang; Chen, Kevin; Javey, Ali; Cho, Gyoujin

    2015-12-01

    Roll-to-roll (R2R) printing has been pursued as a commercially viable high-throughput technology to manufacture flexible, disposable, and inexpensive printed electronic devices. However, in recent years, pessimism has prevailed because of the barriers faced when attempting to fabricate and integrate thin film transistors (TFTs) using an R2R printing method. In this paper, we report 20 × 20 active matrices (AMs) based on single-walled carbon nanotubes (SWCNTs) with a resolution of 9.3 points per inch (ppi) resolution, obtained using a fully R2R gravure printing process. By using SWCNTs as the semiconducting layer and poly(ethylene terephthalate) (PET) as the substrate, we have obtained a device yield above 98%, and extracted the key scalability factors required for a feasible R2R gravure manufacturing process. Multi-touch sensor arrays were achieved by laminating a pressure sensitive rubber onto the SWCNT-TFT AM. This R2R gravure printing system overcomes the barriers associated with the registration accuracy of printing each layer and the variation of the threshold voltage (Vth). By overcoming these barriers, the R2R gravure printing method can be viable as an advanced manufacturing technology, thus enabling the high-throughput production of flexible, disposable, and human-interactive cutting-edge electronic devices based on SWCNT-TFT AMs.

  3. Development of a Carbon Nanotube-Based Touchscreen Capable of Multi-Touch and Multi-Force Sensing

    Directory of Open Access Journals (Sweden)

    Wonhyo Kim

    2015-11-01

    Full Text Available A force sensing touchscreen, which detects touch point and touch force simultaneously by sensing a change in electric capacitance, was designed and fabricated. It was made with single-walled carbon nanotubes (SWCNTs which have better mechanical and chemical characteristics than the indium-tin-oxide transparent electrodes used in most contemporary touchscreen devices. The SWCNTs, with a transmittance of about 85% and electric conductivity of 400 Ω per square; were coated and patterned on glass and polyethyleneterephthalate (PET film substrates. The constructed force sensing touchscreen has a total size and thickness of 62 mm × 100 mm × 1.4 mm, and is composed of 11 driving line and 19 receiving line channels. The gap between the channels was designed to be 20 µm, taking visibility into consideration, and patterned by a photolithography and plasma etching processes. The mutual capacitance formed by the upper and lower transparent electrodes was initially about 2.8 pF and, on applying a 500 gf force with a 3 mm diameter tip, it showed a 25% capacitance variation. Furthermore, the touchscreen can detect multiple touches and forces simultaneously and is unaffected by touch material characteristics, such as conductance or non-conductance.

  4. Effect of a concave grid mesh in a carbon nanotube-based field emission X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Suk; Castro, Edward Joseph D. [Regional Innovation Center for Next Generation Industrial Radiation Technology, Division of Microelectronics and Display Technology, Iksan (Korea, Republic of); Lee, Choong Hun, E-mail: chlee12345@gmail.com [Regional Innovation Center for Next Generation Industrial Radiation Technology, Division of Microelectronics and Display Technology, Iksan (Korea, Republic of); Solar Cell Research Institute, Wonkwang University, Iksan (Korea, Republic of)

    2014-10-15

    Highlights: • Successful design using a concave grid mesh for the focusing electron. • Much better X-ray image due to the concave grid mesh. • Higher anode current efficiency using the concave grid mesh versus a flat grid mesh. - Abstract: This study introduces a simple approach to improve the X-ray image quality produced by the carbon nanotube (CNT) field emitter X-ray source by altering the geometrical shape of the grid mesh from the conventional flat shape to a concave one in a typical triode structure. The concave shape of the grid electrode increases the effective number of the grid cells in the mesh, which exerted an electric field in the direction of the emitted electrons, thereby increasing the emission current reaching the anode. Furthermore, the curved mesh (concave grid mesh), which was responsible for the extraction of electrons from the field emitter, exhibited a focusing effect on the electron beam trajectory thereby, reducing the focal spot size impinging on the anode and resulted in a better spatial resolution of the X-ray images produced.

  5. Characterization and In Vitro Sustained Release of Silibinin from pH Responsive Carbon Nanotube-Based Drug Delivery System

    Directory of Open Access Journals (Sweden)

    Julia M. Tan

    2014-01-01

    Full Text Available The objective of the present study was to develop and characterize an in vitro sustained release formulation of silibinin (SB using commercially available carboxylated multiwalled carbon nanotubes (COOH-MWCNTs and to investigate cytotoxicity action of the synthesized nanohybrid (SB-MWCNTs. The resulting nanohybrid was characterized with Fourier transform infrared (FTIR, Raman spectroscopy, thermogravimetric analysis (TGA, ultraviolet-visible spectrophotometry (UV-Vis, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. FTIR, Raman spectroscopy, and TGA analysis confirmed the adsorption of SB molecules to the COOH-MWCNTs. The release of SB from the COOH-MWCNTs nanocarrier was found to be sustained and pH-dependent. The maximum percentage release of SB from the nanocarrier reached approximately 96.6% and 43.1% within 1000 minutes when exposed to pH 7.4 and pH 4.8 solutions, respectively. It was observed that the release of kinetic behaviour of SB from the MWCNTs nanocarrier conformed well to pseudo-second order kinetic model. The obtained MTT result showed that the SB-MWCNTs exhibited enhanced cytotoxicity to human cancer cell lines in comparison with free SB at lower concentrations. These results suggest that SB-MWCNTs nanohybrid may be a promising nanodrug delivery system with sustained release property for the treatment of cancers.

  6. Role of the Material Electrodes on Resistive Behaviour of Carbon Nanotube-Based Gas Sensors for H2S Detection

    Directory of Open Access Journals (Sweden)

    M. Lucci

    2012-01-01

    Full Text Available Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 μm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H2S gas, in the concentration range 10–100 ppm, using N2 as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H2S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H2S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the Au surfaces by H2S molecules and modification of the contact resistance at the Au/nanotube interface.

  7. Robotic voltammetry with carbon nanotube-based sensors: a superb blend for convenient high-quality antimicrobial trace analysis

    Science.gov (United States)

    Theanponkrang, Somjai; Suginta, Wipa; Weingart, Helge; Winterhalter, Mathias; Schulte, Albert

    2015-01-01

    A new automated pharmacoanalytical technique for convenient quantification of redox-active antibiotics has been established by combining the benefits of a carbon nanotube (CNT) sensor modification with electrocatalytic activity for analyte detection with the merits of a robotic electrochemical device that is capable of sequential nonmanual sample measurements in 24-well microtiter plates. Norfloxacin (NFX) and ciprofloxacin (CFX), two standard fluoroquinolone antibiotics, were used in automated calibration measurements by differential pulse voltammetry (DPV) and accomplished were linear ranges of 1–10 μM and 2–100 μM for NFX and CFX, respectively. The lowest detectable levels were estimated to be 0.3±0.1 μM (n=7) for NFX and 1.6±0.1 μM (n=7) for CFX. In standard solutions or tablet samples of known content, both analytes could be quantified with the robotic DPV microtiter plate assay, with recoveries within ±4% of 100%. And recoveries were as good when NFX was evaluated in human serum samples with added NFX. The use of simple instrumentation, convenience in execution, and high effectiveness in analyte quantitation suggest the merger between automated microtiter plate voltammetry and CNT-supported electrochemical drug detection as a novel methodology for antibiotic testing in pharmaceutical and clinical research and quality control laboratories. PMID:25670899

  8. Carbon Nanotube-based Cold Cathode for High Power MicrowaveVacuum Electronic Devices: A Potential Field Emitter

    Directory of Open Access Journals (Sweden)

    P. Verma

    2008-09-01

    Full Text Available Carbon nanotubes (CNTs can be grown in the form of small, sharp spikes capable of carrying very highcurrent densities which suggest great potential application of CNTs as cold cathode in high power microwavevacuum device applications. These cold cathode vacuum microwave devices are expected to be ideally suitedfor air-borne and space applications. This paper  reports the initial efforts made in the development of coldcathode using PECVD grown vertically-aligned matrix of CNTs with uniform height and optimum tip densityon silicon substrate. The high aspect ratio (of the order of 10,000 and novel electrical, mechanical, and thermalproperties of the CNT are found to be very attractive characteristics for emission of large and stable currentdensities at reasonably low field. The field emission current voltage characteristics of a typical cathode gaveemission current density in excess of 35 mA/cm2 at reasonably low field. The emission current in most of thesamples is found to be stable over long period of time but is greatly effected by the vacuum condition duringmeasurement. The initial measured data suggests great promise for achieving high current densities at practicalelectric fields.Defence Science Journal, 2008, 58(5, pp.650-654, DOI:http://dx.doi.org/10.14429/dsj.58.1688

  9. Robotic voltammetry with carbon nanotube-based sensors: a superb blend for convenient high-quality antimicrobial trace analysis

    Directory of Open Access Journals (Sweden)

    Theanponkrang S

    2015-01-01

    Full Text Available Somjai Theanponkrang,1,2 Wipa Suginta,2,3 Helge Weingart,4 Mathias Winterhalter,4 Albert Schulte1,2 1School of Chemistry, 2Biochemistry–Electrochemistry Research Unit, Institute of Science, 3School of Biochemistry, Suranaree University of Technology, Nakhon Ratchasima, Thailand; 4Life Sciences, School of Engineering and Science, Jacobs University Bremen, Bremen, Germany Abstract: A new automated pharmacoanalytical technique for convenient quantification of redox-active antibiotics has been established by combining the benefits of a carbon nanotube (CNT sensor modification with electrocatalytic activity for analyte detection with the merits of a robotic electrochemical device that is capable of sequential nonmanual sample measurements in 24-well microtiter plates. Norfloxacin (NFX and ciprofloxacin (CFX, two standard fluoroquinolone antibiotics, were used in automated calibration measurements by differential pulse voltammetry (DPV and accomplished were linear ranges of 1–10 µM and 2–100 µM for NFX and CFX, respectively. The lowest detectable levels were estimated to be 0.3±0.1 µM (n=7 for NFX and 1.6±0.1 µM (n=7 for CFX. In standard solutions or tablet samples of known content, both analytes could be quantified with the robotic DPV microtiter plate assay, with recoveries within ±4% of 100%. And recoveries were as good when NFX was evaluated in human serum samples with added NFX. The use of simple instrumentation, convenience in execution, and high effectiveness in analyte quantitation suggest the merger between automated microtiter plate voltammetry and CNT-supported electrochemical drug detection as a novel methodology for antibiotic testing in pharmaceutical and clinical research and quality control laboratories. Keywords: antibiotics, electroanalysis, automation, microtiter plates, pharmaceutical screening, pharmacoanalytics

  10. Targeted Control of Permeability Using Carbonate Dissolution/Precipitation Reactions

    Science.gov (United States)

    Clarens, A. F.; Tao, Z.; Plattenberger, D.

    2016-12-01

    Targeted mineral precipitation reactions are a promising approach for controlling fluid flow in the deep subsurface. Here we studied the potential to use calcium and magnesium bearing silicates as cation donors that would react with aqueous phase CO2 under reservoir conditions to form solid carbonate precipitates. Preliminary experiments in high pressure and temperature columns suggest that these reactions can effectively lower the permeability of a porous media. Wollastonite (CaSiO3) was used as the model silicate, injected as solid particles into the pore space of a packed column, which was then subsequently flooded with CO2(aq). The reactions occur spontaneously, leveraging the favorable kinetics that occur at the high temperature and pressure conditions characteristic of the deep subsurface, to form solid phase calcium carbonate (CaCO3) and amorphous silica (SiO2) within the pore space. Both x-ray tomography imaging of reacted columns and electron microscopy imaging of thin sections were used to characterize where dissolution/precipitation occurred within the porous media. The spatial distribution of the products was closely tied to the flow rate and the duration of the experiment. The SiO2 product precipitated in close spatial proximity to the CaSiO3 reactant. The CaCO3 product, which is sensitive to the low pH and high pCO2 brine, precipitated out of solution further down the column as Ca2+ ions moved with the brine. The permeability of the columns decreased by several orders of magnitude after injecting the CaSiO3 particles. Following carbonation, the permeability decreased even further as precipitates filled flow paths within the pore network. A pore network model was developed to help understand the interplay between precipitation kinetics and flow in altering the permeability of the porous media. The effect of particle concentration and size, pore size, reaction time, and pCO2, are explored on pore/fracture aperture and reaction extent. To provide better

  11. Thermal effects on nonlinear vibration of a carbon nanotube-based mass sensor using finite element analysis

    Science.gov (United States)

    Kang, Dong-Keun; Kim, Chang-Wan; Yang, Hyun-Ik

    2017-01-01

    In the present study we carried out a dynamic analysis of a CNT-based mass sensor by using a finite element method (FEM)-based nonlinear analysis model of the CNT resonator to elucidate the combined effects of thermal effects and nonlinear oscillation behavior upon the overall mass detection sensitivity. Mass sensors using carbon nanotube (CNT) resonators provide very high sensing performance. Because CNT-based resonators can have high aspect ratios, they can easily exhibit nonlinear oscillation behavior due to large displacements. Also, CNT-based devices may experience high temperatures during their manufacture and operation. These geometrical nonlinearities and temperature changes affect the sensing performance of CNT-based mass sensors. However, it is very hard to find previous literature addressing the detection sensitivity of CNT-based mass sensors including considerations of both these nonlinear behaviors and thermal effects. We modeled the nonlinear equation of motion by using the von Karman nonlinear strain-displacement relation, taking into account the additional axial force associated with the thermal effect. The FEM was employed to solve the nonlinear equation of motion because it can effortlessly handle the more complex geometries and boundary conditions. A doubly clamped CNT resonator actuated by distributed electrostatic force was the configuration subjected to the numerical experiments. Thermal effects upon the fundamental resonance behavior and the shift of resonance frequency due to attached mass, i.e., the mass detection sensitivity, were examined in environments of both high and low (or room) temperature. The fundamental resonance frequency increased with decreasing temperature in the high temperature environment, and increased with increasing temperature in the low temperature environment. The magnitude of the shift in resonance frequency caused by an attached mass represents the sensing performance of a mass sensor, i.e., its mass detection

  12. Development of Acidizing Techniques for Low-permeability Carbonate Reservoirs

    Institute of Scientific and Technical Information of China (English)

    Liu Tongbin

    1996-01-01

    @@ Geological Background In accordance with gas reservoir occurrence, reserve type and trap type, the discovered and developed carbonate reservoirs in Sichuan Basin can be classified into the following three types: the first type is the layered porous gas reservoir (including porous and fractured porous gas reservoir), mainly distributed in East Sichuan area; the second is the block vug bottom water drive gas reservoir; the third is the irregular gas reservoir with fracture system, mainly distributed in the areas of South Sichuan and Southwest Sichuan. The reservoirs of these gas pools are mainly of carbonatite. The matrix porosity and permeability of carbonatite are very low, the porosity being below 1% - 3% and the permeability, 0.1×10-3-8× 10-3 μm2. Also the throat capillary resistance force is considerable with the mid-value width of the throat (γ50)of 0.1 - 4 μm, most below 2 μm. Owing to the low permeability and porosity as well as the serious heterogeneity of the reservoir, the productivi ty of gas wells changes greatly.

  13. Study on Permeability Change Rule of Different Rank Coals by Injecting Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Guo Hui

    2015-01-01

    Full Text Available This paper provides an experimental support for increasing the flow conductivity of coal reservoir by identifying permeability change rule caused by reactions with different minerals in coal after injecting carbon dioxide. Based on measurement of nitrogen adsorption, mineral composition and permeability of medium-high rank coal in Tunlan mine and Sihe mine, it is used to investigate the permeability change rule caused by reactions with different minerals in coal and its improving effect after injecting carbon dioxide. A permeability change model was established by making a nonlinear regression analysis of the initial permeability, the reaction time and the improved permeability. The results showed that as a result of CO2-water-rock interaction, permeability of medium-high rank coal increases at first and then decreases with time going by after injecting carbon dioxide. The permeability of Sihe coal samples reaches maximum value earlier than that of Tunlan coal samples. Improving effect of permeability of Sihe coal samples is better than that of Tunlan coal samples. The initial permeability which is too large or too small is insensitive to the change of permeability, while the medium permeability within 0.1--0.2×10-3μm2 is more favorable. The reliability of the mathematical model is verified by the experiment. The results can also provide a theoretical basis for the analysis of permeability change after injecting carbon dioxide.

  14. Photoluminescent carbon nanotubes interrogate the permeability of multicellular tumor spheroids

    Science.gov (United States)

    Shah, Janki; Roxbury, Daniel; Paknejad, Navid; Heller, Daniel A.

    2015-01-01

    Nanomaterials have been extensively investigated for cancer drug delivery and imaging applications. Nanoparticles that show promise in two-dimensional cell culture systems often fail in more complex environments, possibly due to the lack of penetration in dense, three-dimensional structures. Multicellular tumor spheroids are an emerging model system to investigate interactions of nanoparticles with 3D in vitro cell culture environments. Using the intrinsic near-infrared emission of semiconducting carbon nanotubes to optically reconstruct their localization within a three-dimensional volume, we resolved the relative permeability of two different multicellular tumor spheroids. Nanotube photoluminescence revealed that nanotubes rapidly internalized into MCF-7 breast cancer cell-derived spheroids, whereas they exhibited little penetration into spheroids derived from SK-136, a cell line that we developed from murine liver cancer. Characterization of the spheroids by electron microscopy and immunohistochemistry revealed large differences in the extracellular matrix and interstitial spacing, which correlated directly with nanotube penetration. This platform portends a new approach to characterize the permeability of living multicellular environments. PMID:26456974

  15. Carbonate Microfabrics Permeability Characteristics of Continental Slope and Deep-Water Carbonates from a Microfabric Perspective

    Science.gov (United States)

    1994-01-01

    carbonate sediments composed of sediments recovered from Exuma Sound and north of Little aragonite needles have higher permeabilities (I X 10-5 cm/s) Bahama...environments and are useful for interpreting the geological record. The northern Little Bahama Bank and Exuma Sound slopes sampled in this study (Fig...slope, an early stage in the evolution of carbonate slopes. Exuma "Sound, much steeper at 120 to 140, represen:s thoi final-" erosional bypass stage of

  16. Permeability variation characteristics of coal after injecting carbon dioxide into a coal seam

    Institute of Scientific and Technical Information of China (English)

    Ni Xiaoming; Li Quanzhong; Wang Yanbin; Gao Shasha

    2015-01-01

    A theoretical basis for the optimization of carbon dioxide injection parameters and the development of the drainage system can be provided by identifying the permeability change characteristic of coal and rock after injection of carbon dioxide into the coal seam. Sihe, Yuwu, and Changcun mines were used as research sites. Scanning electron microscopy and permeability instruments were used to measure coal properties such as permeability and surface structure of the coal samples at different pH values of carbon dioxide solution and over different timescales. The results show that the reaction between minerals in coal and carbonate solution exhibit positive and negative aspects of permeability-the dissolution reaction between carbonate minerals in coal and acid solution improves the conductivity of coal whilst, on the other hand, the clay minerals in the coal (mainly including montmorillonite, illite and kaolinite) exhibit expansion as a result of ion exchange with the H+in acid solution, which has a negative effect on the per-meability of the coal. The permeability of coal samples increased at first and then decreased with immer-sion time, and when the soaking time is 2–3 months the permeability of the coal reached a maximum. In general, for coals with permeabilities less than 0.2 mD or greater than 2 mD, the effect on the permeabil-ity is low;when the permeability of the coal is in the range 0.2–2 mD, the effect on the permeability is highest. Research into permeability change characteristics can provide a theoretical basis for carbon diox-ide injection under different reservoir permeability conditions and subsequent drainage.

  17. Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

    Science.gov (United States)

    Poston, S. W.

    1991-01-01

    The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.

  18. Simulation of permeability evolution of leakage pathway in carbonate-rich caprocks in carbon sequestration

    Science.gov (United States)

    Guo, B.; Fitts, J. P.; Dobossy, M. E.; Peters, C. A.

    2013-12-01

    Geologic carbon sequestration in deep saline aquifers is a promising strategy for mitigating climate change. A major concern is the possibility of brine and CO2 migration through the caprock such as through fractures and faults. In this work, we examine the extent to which mineral dissolution will substantially alter the porosity and permeability of caprock leakage pathways as CO2-acidified brine flows through them. Three models were developed. Firstly, a reactive transport model, Permeability Evolution of Leakage pathway (PEL), was developed to simulate permeability evolution of a leakage pathway during the injection period, and assumes calcite is the only reactive mineral. The system domain is a 100 m long by 0.2 m diameter cylindrical flow path with fixed boundaries containing a rock matrix with an initial porosity of 30% and initial permeability of 1×10-13 m2. One example result is for an initial calcite volume fraction (CVF) of 0.20, in which all the calcite is dissolved after 50 years and the permeability reaches 3.2×10-13 m2. For smaller values of CVF, the permeability reaches its final value earlier but the increase in permeability is minimal. For a large value of CVF such as 0.50, the permeability could eventually reach 1×10-12 m2, but the large amount of dissolved calcium buffers the solution and slows the reaction. After 50 years the permeability change is negligible. Thus, there is a non-monotonic relationship between the amount of calcite in the rock and the resulting permeability change because of the competing dynamics of calcite dissolution and alkalinity build-up. In the second model, PEL was coupled to an existing basin-scale multiphase flow model, Princeton's Estimating Leakage Semi-Analytical (ELSA) model. The new model, ELSA-PEL, estimates the brine and CO2 leakage rates during the injection period under conditions of permeability evolution. The scenario considered in this work is for 50 years of CO2 injection into the Mt. Simon formation in

  19. Estimating permeability of carbonate rocks from porosity and v(p)/v(s)

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke; Baechle, G.; Eberli, G.P.

    2007-01-01

    We present a method for predicting permeability from sonic and density data. The method removes the porosity effect on the ratio upsilon(p)/upsilon(s), of dry rock, and it addresses the specific surface as an indirect measure of permeability. We look at ultrasonic data, porosity......, and the permeability of 114 carbonate core plugs. In doing so, we establish an empirical relationship between the specific surface of the solid phase (as calculated by Kozeny's equation) and upsilon(p)/upsilon(s) (linearly transformed to remove the porosity effect). One must view the specific surface derived by using...... settings. We find a reasonable match between predicted and measured permeability. The match is better for samples with carbonate mud-filled depositional textures than for carbonate mud-poor depositional textures. Diagenetic factors such as vuggy porosity decrease the predictability of permeability....

  20. Relative permeability experiments of carbon dioxide displacing brine and their implications for carbon sequestration.

    Science.gov (United States)

    Levine, Jonathan S; Goldberg, David S; Lackner, Klaus S; Matter, Juerg M; Supp, Michael G; Ramakrishnan, T S

    2014-01-01

    To mitigate anthropogenically induced climate change and ocean acidification, net carbon dioxide emissions to the atmosphere must be reduced. One proposed option is underground CO2 disposal. Large-scale injection of CO2 into the Earth's crust requires an understanding of the multiphase flow properties of high-pressure CO2 displacing brine. We present laboratory-scale core flooding experiments designed to measure CO2 endpoint relative permeability for CO2 displacing brine at in situ pressures, salinities, and temperatures. Endpoint drainage CO2 relative permeabilities for liquid and supercritical CO2 were found to be clustered around 0.4 for both the synthetic and natural media studied. These values indicate that relative to CO2, water may not be strongly wetting the solid surface. Based on these results, CO2 injectivity will be reduced and pressure-limited reservoirs will have reduced disposal capacity, though area-limited reservoirs may have increased capacity. Future reservoir-scale modeling efforts should incorporate sensitivity to relative permeability. Assuming applicability of the experimental results to other lithologies and that the majority of reservoirs are pressure limited, geologic carbon sequestration would require approximately twice the number of wells for the same injectivity.

  1. Enhancing the electrical conductivity of carbon-nanotube-based transparent conductive films using functionalized few-walled carbon nanotubes decorated with palladium nanoparticles as fillers.

    Science.gov (United States)

    Li, Yu-An; Tai, Nyan-Hwa; Chen, Swe-Kai; Tsai, Tsung-Yen

    2011-08-23

    This work demonstrates the processing and characterization of the transparent and highly electrically conductive film using few-walled carbon nanotubes (FWCNTs) decorated with Pd nanoparticles as fillers. The approach included functionalizing the FWCNTs, immersing them in an aqueous solution of palladate salts, and subsequently subjecting them to a reduction reaction in H(2). Field-emission scanning electron microscopy and transmission electron microscopy images showed that the functionalized FWCNTs (f-FWCNTs) were decorated with uniform and homogeneous Pd nanoparticles with an average diameter of 5 nm. A shift of the G-band to a higher frequency in the Raman spectra of the Pd-decorated f-FWCNTs (Pd@f-FWCNTs) illustrates that the p-type doping effect was enhanced. X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy showed that PdCl(2) was the primary decoration compound on the f-FWCNTs prior to the reduction reaction and that Pd nanoparticles were the only decorated nanoparticles after H(2) reduction. The contact resistance between the metallic materials and the semiconducting CNTs in FWCNTs, controlled by the Schottky barrier, was significantly decreased compared to the pristine FWCNTs. The decrease in contact resistance is attributed to the 0.26 eV increase of the work function of the Pd@f-FWCNTs. Extremely low sheet resistance of 274 ohm/sq of the poly(ethylene terephthalate) substrates coated with Pd@f-FWCNTs was attained, which was 1/25 the resistance exhibited by those coated with FWCNTs, whereas the same optical transmittance of 81.65% at a wavelength of 550 nm was maintained. © 2011 American Chemical Society

  2. Determination of the effective Young's modulus of vertically aligned carbon nanotube arrays: a simple nanotube-based varactor

    Energy Technology Data Exchange (ETDEWEB)

    Olofsson, Niklas; Eriksson, Anders [Department of Physics, Goeteborg University, SE-41296 Goeteborg (Sweden); Ek-Weis, Johan; Campbell, Eleanor E B [School of Chemistry, Edinburgh University, West Mains Road, Edinburgh EH9 3JJ (United Kingdom); Idda, Tonio, E-mail: eleanor.campbell@ed.ac.u [LAAS-CNRS, 7 Avenue du Colonel Roche, 31077 Toulouse Cedex (France)

    2009-09-23

    The electromechanical properties of arrays of vertically aligned multiwalled carbon nanotubes were studied in a parallel plate capacitor geometry. The electrostatic actuation was visualized using both optical microscopy and scanning electron microscopy, and highly reproducible behaviour was achieved for actuation voltages below the pull-in voltage. The walls of vertically aligned carbon nanotubes behave as solid cohesive units. The effective Young's modulus for the carbon nanotube arrays was determined by comparing the actuation results with the results of electrostatic simulations and was found to be exceptionally low, of the order of 1-10 MPa. The capacitance change and Q-factor were determined by measuring the frequency dependence of the radio-frequency transmission. Capacitance changes of over 20% and Q-factors in the range 100-10 were achieved for a frequency range of 0.2-1.5 GHz.

  3. Permeability, diffusivity and solubility of carbon dioxide in fluoropolymers: An experimental and modeling study

    DEFF Research Database (Denmark)

    Neela, Vasu; von Solms, Nicolas

    2014-01-01

    . Using a high-pressure permeation cell, the permeability and diffusivity of carbon dioxide were measured in several polymers used as packing and sealing materials. These were the fluoropolymers PTFE, FKM and TFM, both pure and containing glass, graphite, Ekonol and polysulfone as additives...

  4. Developments in Analytical Chemistry: Acoustically Levitated Drop Reactors for Enzyme Reaction Kinetics and Single-Walled Carbon Nanotube-Based Sensors for Detection of Toxic Organic Phosphonates

    Science.gov (United States)

    Field, Christopher Ryan

    2009-01-01

    Developments in analytical chemistry were made using acoustically levitated small volumes of liquid to study enzyme reaction kinetics and by detecting volatile organic compounds in the gas phase using single-walled carbon nanotubes. Experience gained in engineering, electronics, automation, and software development from the design and…

  5. Evolution of permeability and microstructure of tight carbonates due to numerical simulation of calcite dissolution

    Science.gov (United States)

    Miller, Kevin; Vanorio, Tiziana; Keehm, Youngseuk

    2017-06-01

    The current study concerns fundamental controls on fluid flow in tight carbonate rocks undergoing CO2 injection. Tight carbonates exposed to weak carbonic acid exhibit order of magnitude changes in permeability while maintaining a nearly constant porosity with respect to the porosity of the unreacted sample. This study aims to determine—if not porosity—what are the microstructural changes that control permeability evolution in these rocks? Given the pore-scale nature of chemical reactions, we took a digital rock physics approach. Tight carbonate mudstone was imaged using X-ray microcomputed tomography. We simulated calcite dissolution using a phenomenological numerical model that stands from experimental and microstructural observations under transport-limited reaction conditions. Fluid flow was simulated using the lattice-Boltzmann method, and the pore wall was adaptively eroded at a rate determined by the local surface area and velocity magnitude, which we use in place of solvent flux. We identified preexisting, high-conductivity fluid pathways imprinted in the initial microstructure. Though these pathways comprise a subset of the total connected porosity, they accommodated 80 to 99% of the volumetric flux through the digital sample and localized dissolution. Porosity-permeability evolution exhibited two stages: selective widening of narrow pore throats that comprised preferential pathways and development and widening of channels. We quantitatively monitored attributes of the pore geometry, namely, porosity, specific surface area, tortuosity, and average hydraulic diameter, which we qualitatively linked to permeability. This study gives a pore-scale perspective on the microstructural origins of laboratory permeability-porosity trends of tight carbonates undergoing transport-limited reaction with CO2-rich fluid.

  6. NEURAL NETWORK ANALYSIS APPLICATION TO PERMEABILITY DETERMINATION OF FIBERGLASS AND CARBON PREFORMS

    Institute of Scientific and Technical Information of China (English)

    Hossein Golestanian; Mehrdad Poursina

    2009-01-01

    Preform permeability is an important process parameter in liquid injection molding of composite parts.This parameter is currently determined with time consuming and expensive experimental procedures.This paper presents the application of a back-propagation neural network to predicting fiber bed permeability of three types of reinforcement mats.Resin flow experiments were performed to simulate the injection cycle of a resin transfer molding process.The results of these experiments were used to prepare a training set for the back propagation neural network program.The reinforcements consisted of plain-weave carbon,plain-weave fiberglass,and chopped fiberglass mats.The effects of reinforcement type,porosity and injection pressure on fiber bed permeability in the preform principal directions were investigated.Therefore,in the training of the neural network reinforcement type,these process parameters were used as the input data.Fiber bed permeability values were the specified output of the program.As a result of the specified parameters,the program was able to estimate fiber bed permeability in the preform principal directions for any given processing condition.The results indicate that neural network may be used to predict preform permeability.

  7. Experimental measurements of the permeability of fibrous carbon at high temperature

    CERN Document Server

    Panerai, Francesco; Cochell, Thomas J; Schroeder, Olivia M; Mansour, Nagi N; Wright, Michael J; Martin, Alexandre

    2016-01-01

    A series of experiments was performed to obtain permeability data on FiberForm(R), a commercial carbon preform used for manufacturing thermal protection systems. A porous sample was placed in a quartz flow-tube heated by an isothermal furnace. The setup was instrumented to measure mass flow through and pressure drop across the sample. The intrinsic permeability and the Klinkenberg correction, which accounts for rarefied effects, were computed from the experimental data. The role of the gas temperature and pressure on the effective permeability is shown, and it is demonstrated that with proper data reduction, the intrinsic permeability is strictly a function of the micro-structure of the material. A function for the effective permeability of FiberForm, dependent on temperature, pressure, pore geometry, and type of gas is proposed. The intrinsic permeability was evaluated at $K_0 = 5.57 \\times 10^{-11}$ m$^2$, with a Klinkenberg parameter of $8c/d_p = 2.51 \\times 10^5$ m$^{-1}$ and a reference porosity of $\\phi...

  8. Characterization and prevention of formation damage for fractured carbonate reservoir formations with low permeability

    Institute of Scientific and Technical Information of China (English)

    Shu Yong; Yan Jienian

    2008-01-01

    Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure,lithology, porosity, permeability and mineral components all affect the potential for formation damage.The experimental results showed that the permeability loss was 83.8%-98.6% caused by stress sensitivity,and was 27.9%-48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows: the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide (MMH) drilling fluid system was developed,which was mainly composed of low-fluorescence shale control agent, filtration control agent, lowfluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability (over 85%) of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate (API filtration less than 5 ml after aging at 120 ℃ for 4 hours). Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid.Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.

  9. Effect of the Carbon-Nanotube Length on Water Permeability

    Institute of Scientific and Technical Information of China (English)

    LI Jing-Yuan; YANG Zai-Xing; FANG Hai-Ping; ZHOU Ru-Hong; TANG Xiao-Wei

    2007-01-01

    Effect of the carbon nanotube (CNT) channel length on the water flow through the CNT is studied using molecular dynamics simulations. The water flow is found to decay with the channel length (~ 1/N2.3, N is the number of carbon rings along the nanotube axis), much faster than that predicted by a previous continuous-time random walk (CTRW) model (~ 1/N). This unexpected decay rate of flow is found to result from the weakening of the correlation of the concerted motion of the water molecules inside the CNT. An improved CTRW model is then proposed by taking into account of this effect. Meanwhile, the diffusion constant of water molecules inside CNTs with various lengths is found to be relatively invariant, which results in a relatively constant hopping rate.

  10. Passively Q-switched Er,Yb:GdAl3(BO3)4 laser with single-walled carbon nanotube based saturable absorber

    Science.gov (United States)

    Gorbachenya, K. N.; Kisel, V. E.; Yasukevich, A. S.; Prudnikova, M. B.; Maltsev, V. V.; Leonyuk, N. I.; Choi, S. Y.; Rotermund, F.; Kuleshov, N. V.

    2017-03-01

    We demonstrate a passively Q-switched Er,Yb:GdAl3(BO3)4 diode-pumped laser emitting near 1.5 µm. By using a single-walled carbon nanotube (SWCNT) as a saturable absorber, Q-switched laser pulses with energy of 0.8 µJ and duration of 130 ns at a maximum repetition rate of 500 kHz were obtained at 1550 nm.

  11. Permeability characterization of stitched carbon fiber preforms by fiber optic sensors

    Directory of Open Access Journals (Sweden)

    V. Antonucci

    2011-12-01

    Full Text Available The in-plane and through thickness permeability of unidirectional stitched carbon fiber preforms have been determined through vacuum infusion tests. The impregnation of various dry preforms with different stitching characteristics has been monitored by fiber optic sensors that have been stitched together with the dry tow to manufacture the dry preform. The experimental infusion times have been fitted by a numerical procedure based on Finite Element (FE processing simulations. A good agreement between the numerical and experimental infusion times has been found demonstrating the potentiality of the fiber sensor system as suitable tool to evaluate impregnation times and permeability characteristics.

  12. Ultra-high speed all-optical signal processing using silicon waveguides and a carbon nanotubes based mode-locked laser

    DEFF Research Database (Denmark)

    Ji, Hua

    This thesis concerns the use of nano-engineered silicon waveguides for ultra-high speed optical serial data signal processing. The fundamental nonlinear properties of nano-engineered silicon waveguides are characterized. Utilizing the nonlinear effect in nano-engineered silicon waveguides...... for demultiplexing of 1.28 Tbit/s optical time division multiplexing data signal is investigated. A sampling system for ultra-high speed signal waveforms based on nano-engineered silicon waveguide is explored. To set up a sampling source, using carbon nanotubes for generating ultra-short pulses is pursued. A silicon...

  13. Yeast and carbon nanotube based biocatalyst developed by synergetic effects of covalent bonding and hydrophobic interaction for performance enhancement of membraneless microbial fuel cell.

    Science.gov (United States)

    Christwardana, Marcelinus; Kwon, Yongchai

    2017-02-01

    Membraneless microbial fuel cell (MFC) employing new microbial catalyst formed as yeast cultivated from Saccharomyces cerevisiae and carbon nanotube (yeast/CNT) is suggested. To analyze its catalytic activity and performance and stability of MFC, several characterizations are performed. According to the characterizations, the catalyst shows excellent catalytic activities by facile transfer of electrons via reactions of NAD, FAD, cytochrome c and cytochrome a3, while it induces high maximum power density (MPD) (344mW·m(-2)). It implies that adoption of yeast induces increases in catalytic activity and MFC performance. Furthermore, MPD is maintained to 86% of initial value even after eight days, showing excellent MFC stability.

  14. Development of carbon nanotubes based gas diffusion layers by in situ chemical vapor deposition process for proton exchange membrane fuel cells

    Science.gov (United States)

    Kannan, A. M.; Kanagala, P.; Veedu, V.

    A proprietary in situ chemical vapor deposition (CVD) process was developed for gas diffusion layer (GDL) by growing a micro-porous layer on the macro-porous, non-woven fibrous carbon paper. The characteristics of the GDL samples such as, surface morphology, wetting characteristics, and cross-section were characterized using electron microscopes, goniometer and focused ion beam, respectively. Fuel cell performance of the GDLs was evaluated using single cell with hydrogen/oxygen as well as hydrogen/air at ambient pressure, at elevated temperature and various RH conditions using Nafion-212 as an electrolyte. The GDLs with in situ growth of micro-porous layers containing carbon nanotubes (CNTs) without any hydrophobic agent showed significant improvement in mechanical robustness as well as fuel cell performance at elevated temperature at lower RH conditions. The micro-porous layer of the GDLs as seen under scanning electron microscope showed excellent surface morphology with surface homogeneity through reinforcement by the multi-walled CNTs.

  15. NO x gas detection characteristics in FET-type multi-walled carbon nanotube-based gas sensors for various electrode spacings

    Science.gov (United States)

    Kim, Hyun Soo; Jang, Kyung Uk; Kim, Tae Wan

    2016-03-01

    In this study, we fabricated a p-channel FET-type NO x gas sensor by using multi-walled carbon nanotubes (MWCNTs). Carbon nanotubes (CNTs) have good electronic, chemical-stability, and sensitivity characteristics. In particular, gas sensors require characteristics such as high speed, selectivity, and sensitivity. The fabricated sensor was used to detect NO x gas for different values of the gate-source voltage (V gs ) and the electrode spacings (30, 60, 90, and 120 μm). The gas sensor that absorbed NO x gas molecules showed a decrease in resistance. The sensitivity of the gas sensor was increased by increasing the electrode spacing. Additionally, while changing the Vgs and the temperature inside the chamber for the MWCNT gas sensor, we obtained the sensitivity and the normalized response for detecting NO x gas. We also obtained the adsorption energy (U a ) by using Arrhenius plots based on the reduction of resistance due to voltage variations. The adsorption energy was found to increase with increasing applied voltage.

  16. Electrocatalytic Synthesis of Ammonia at Room Temperature and Atmospheric Pressure from Water and Nitrogen on a Carbon-Nanotube-Based Electrocatalyst.

    Science.gov (United States)

    Chen, Shiming; Perathoner, Siglinda; Ampelli, Claudio; Mebrahtu, Chalachew; Su, Dangsheng; Centi, Gabriele

    2017-03-01

    Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in a flow electrochemical cell operating in gas phase (half-cell for the NH3 synthesis). Iron supported on carbon nanotubes (CNTs) was used as the electrocatalyst in this half-cell. A rate of ammonia formation of 2.2×10(-3)  gNH3  m(-2)  h(-1) was obtained at room temperature and atmospheric pressure in a flow of N2 , with stable behavior for at least 60 h of reaction, under an applied potential of -2.0 V. This value is higher than the rate of ammonia formation obtained using noble metals (Ru/C) under comparable reaction conditions. Furthermore, hydrogen gas with a total Faraday efficiency as high as 95.1 % was obtained. Data also indicate that the active sites in NH3 electrocatalytic synthesis may be associated to specific carbon sites formed at the interface between iron particles and CNT and able to activate N2 , making it more reactive towards hydrogenation.

  17. Nanosecond soliton pulse generation by mode-locked erbium-doped fiber laser using single-walled carbon-nanotube-based saturable absorber.

    Science.gov (United States)

    Ismail, Mohd Afiq; Harun, Sulaiman Wadi; Zulkepely, Nurul Rozullyah; Nor, Roslan Md; Ahmad, Fauzan; Ahmad, Harith

    2012-12-20

    We demonstrate a simple and low cost mode-locked erbium-doped fiber laser (EDFL) operating in the nanosecond region using a single-walled carbon nanotube (SWCNT)-based saturable absorber (SA). A droplet of SWCNT solution is applied on the end of a fiber ferrule, which is then mated to another clean connector ferrule to construct an SA. Then the SA is integrated into a ring EDFL cavity for nanosecond pulse generation. The EDFL operates at around 1570.4 nm, with a soliton-like spectrum with small Kelly sidebands, which confirms the attainment of the anomalous dispersion. It produces a soliton pulse train with a 332 ns width, repetition rate of 909.1 kHz, an average output power of 0.31 mW, and energy of 0.34 nJ at the maximum pump power of 130.8 mW.

  18. Label-free detection of cardiac troponin-I using gold nanoparticles functionalized single-walled carbon nanotubes based chemiresistive biosensor

    Science.gov (United States)

    Rajesh, Sharma, Vikash; Puri, Nitin K.; Singh, Rajiv K.; Biradar, Ashok M.; Mulchanadani, Ashok

    2013-11-01

    We report a specific and ultrasensitive, label-free chemiresistive biosensor based on mercaptopropionic acid capped gold nanoparticles (GNP) functionalized single walled carbon nanotube (SWNT) hybrid for the detection of cardiac specific biomarker troponin-I (cTnI). GNPs were attached to SWNTs through a molecular linker 1-pyrenemethylamine. The highly specific cTnI antibody was covalently immobilized on GNPs through capping agent using carbodiimide coupling reaction. The cTnI interaction to its corresponding antibody was studied with respect to changes in conductance in SWNTs channel, and a detailed field-effect transistor characteristic was delineated. The device exhibited a linear response to cTnI from 0.01 to 10 ng ml-1.

  19. Investigation on the Vibration of Carbon Nanotube Based Mass Sensors%碳纳米管质量传感器振动特性研究

    Institute of Scientific and Technical Information of China (English)

    陈越; 李明林

    2015-01-01

    基于欧拉-伯努利梁理论对单壁碳纳米管质量传感器的振动特性进行研究。分别考虑悬臂梁式和两端固定式碳纳米管质量传感器,研究吸附质量对其谐振频率漂移的影响。推导出任意位置的吸附质量下,碳纳米管质量传感器的等效刚度、等效质量和谐振频率的解析表达式,推导出传感器的非线性应用方程及其简化形式。在特定位置下吸附质量对不同长度碳纳米管谐振频率的影响进行了研究。数值仿真结果表明,对于不同的边界约束和特定的吸附位置条件下,吸附质量越大、碳纳米管的长度越短,导致的碳纳米管频率漂移越大。对于8 nm长的碳纳米管,在悬臂式约束下,吸附质量越远离固定端,引起的频率漂移越大。而在两端固定约束下,则是吸附质量越靠近固定端,频率漂移越大。揭示了传感器的谐振特性,有助于促进碳纳米管在纳机谐振器领域的推广应用。%Vibrational properties of single-wal ed carbon nanotubes ( SWCNTs) as a mass sensor is examined using Euler–Ber-noul i beam theory based approach. ln order to figure out how the attached mass affects the resonant frequency of the carbon nano-tube resonators, the resonators both in bridged and in cantilevered configurations are studied. Firstly, analytical formulas of equiva-lent stiffness, equivalent mass and resonant frequency are developed for CNT-based nanoresonators with attached mass at any lo-cation. ln addition, a simplified form of the nonlinear sensor equation and image analysis of the relationship among load location, the attached mass and resonant frequency have been investigated. Then for different lengths of SWCNTs, the influence of the attached mass in a specific location on the resonant frequency has been derived. The simulation results indicate that in the condition of differ-ent boundary constraints and the specific adsorption location, the heavier

  20. Carbon nanotube-based substrates promote cardiogenesis in brown adipose-derived stem cells via β1-integrin-dependent TGF-β1 signaling pathway

    Directory of Open Access Journals (Sweden)

    Sun H

    2016-09-01

    Full Text Available Hongyu Sun,1,* Yongchao Mou,2,* Yi Li,3,* Xia Li,4,* Zi Chen,2 Kayla Duval,2 Zhu Huang,1 Ruiwu Dai,1 Lijun Tang,1 Fuzhou Tian1 1Department of General Surgery, Chengdu Military General Hospital, Chengdu, People’s Republic of China; 2Thayer School of Engineering, Dartmouth College, Hanover, NH, USA; 3Department of Cardiology, The General Hospital of Chinese People’s Armed Police Forces, Beijing, People’s Republic of China; 4Affiliated Hospital of Academy of Military Medical Sciences, Beijing, People’s Republic of China *These authors contributed equally to this work Abstract: Stem cell-based therapy remains one of the promising approaches for cardiac repair and regeneration. However, its applications are restricted by the limited efficacy of cardiac differentiation. To address this issue, we examined whether carbon nanotubes (CNTs would provide an instructive extracellular microenvironment to facilitate cardiogenesis in brown adipose-derived stem cells (BASCs and to elucidate the underlying signaling pathways. In this study, we systematically investigated a series of cellular responses of BASCs due to the incorporation of CNTs into collagen (CNT-Col substrates that promoted cell adhesion, spreading, and growth. Moreover, we found that CNT-Col substrates remarkably improved the efficiency of BASCs cardiogenesis by using fluorescence staining and quantitative real-time reverse transcription-polymerase chain reaction. Critically, CNTs in the substrates accelerated the maturation of BASCs-derived cardiomyocytes. Furthermore, the underlying mechanism for promotion of BASCs cardiac differentiation by CNTs was determined by immunostaining, quantitative real-time reverse transcription-polymerase chain reaction, and Western blotting assay. It is notable that β1-integrin-dependent TGF-β1 signaling pathway modulates the facilitative effect of CNTs in cardiac differentiation of BASCs. Therefore, it is an efficient approach to regulate cardiac

  1. [Determination of 21 organophosphorus pesticides in tea by gas chromatography-mass spectrometry coupled with hydroxylated multi-walled carbon nanotubes based on dispersive solid-phase extraction].

    Science.gov (United States)

    Rong, Jiefeng; Wei, Hang; Li, Yijun; Huang, Huoshui; Xu, Meizhu

    2016-02-01

    A rapid determination method of 21 organophosphorus pesticides in tea was developed by QuEChERS method using modified multi-walled carbon nanotubes (MWCNTs-OH), primary-secondary amine (PSA) and MgSO4 coupled with gas chromatography-mass spectrometry. The pesticide residues in tea were extracted with a hexane-acetone (2:1, v/v) mixture, and cleaned up by dispersive solid-phase extraction using MWCNTs-OH and primary-secondary amine (PSA) as the sorbents. After centrifugation and filtration, the target compounds were analyzed by gas chromatography-mass spectrometry and quantified by the external standard method. Under the optimized conditions, good linearities were obtained in the range of 0. 01- 0. 50 mg/kg. The average recoveries were in the range of 81. 5% -109. 4% at three spiked levels, with relative standard deviations (RSDs, n = 5 ) of 2. 3% - 10. 6%. The limits of quantification were 0. 001-0. 040 mg/kg. This method is simple, fast, sensitive, cheap, and can meet the requirements of the rapid detection of organophosphorus pesticides in tea.

  2. Multi-walled carbon nanotube-based ternary rare earth (Eu3+, Tb3+) hybrid materials with organically modified silica-oxygen bridge.

    Science.gov (United States)

    Li, Qiu-Ping; Yan, Bing

    2012-08-15

    A series of ternary rare earth (Eu(3+), Tb(3+)) complexes are covalently coated to the 3-aminopropyltriethoxysilane functionalized multi-walled carbon nanotube (MWCNT) by a simple in situ sol-gel method by the bifunctional silylated monomer TTA-Si and TAA-Si (TTA-Si and TAA-Si are 3-(triethoxysilyl)propylisocyanate (TEPIC) modified thenoyltrifluoroacetone (TTA) and trifluoroacetylacetone (TAA), respectively). The resulting materials are characterized by Fourier transform infrared spectra, scanning electronic microscope, transmission electron microscope, thermogravimetric analysis, ultraviolet visible diffused reflection measure, photoluminescence spectra, and X-ray diffraction. The photoluminesce measurements indicated that these hybrids exhibit characteristic red and green luminescence originating from the corresponding ternary rare earth ion (Eu(3+), Tb(3+)). The luminescence quenching effect of MWCNT networks have been successfully restrained by coating a relatively thicker silica-oxygen-based organic-inorganic complex. Furthermore, the fluorescence lifetimes and emission quantum efficiencies of Eu(3+) hybrid materials are also determined. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Photothermal-Responsive Single-Walled Carbon Nanotube-Based Ultrathin Membranes for On/Off Switchable Separation of Oil-in-Water Nanoemulsions.

    Science.gov (United States)

    Hu, Liang; Gao, Shoujian; Ding, Xianguang; Wang, Dong; Jiang, Jiang; Jin, Jian; Jiang, Lei

    2015-05-26

    Oil-contaminated wastewater threatens our environment and health, especially that stabilized by surfactants. Conventional separation protocols become invalid for those surfactant-stabilized nanoemulsions due to their nanometer-sized droplets and extremely high stability. In this paper, photothermal-responsive ultrathin Au nanorods/poly(N-isopropylacrylamide-co-acrylamide) cohybrid single-walled carbon nanotube (SWCNT) nanoporous membranes are constructed. Such membranes are capable of separating oil-in-water nanoemulsions with a maximum flux up to 35 890 m(2)·h(-1)·bar(-1) because they feature hydrophilicity, underwater oleophobicity, and nanometer pore sizes. It is remarkable that the permeation flux can be simply modulated by light illumination during the process of separation, due to the incorporation of thermal-responsive copolymers and Au nanorods. Meanwhile, it shows ultrahigh separation efficiency (>99.99%) and desired antifouling and recyclability properties. We anticipate that our ultrathin photothermal-responsive SWCNT-based membranes provide potential for the generation of point-of-use water treatment devices.

  4. Rapid extraction and quantitative detection of the herbicide diuron in surface water by a hapten-functionalized carbon nanotubes based electrochemical analyzer.

    Science.gov (United States)

    Sharma, Priyanka; Bhalla, Vijayender; Tuteja, Satish; Kukkar, Manil; Suri, C Raman

    2012-05-21

    A solid phase extraction micro-cartridge containing a non-polar polystyrene absorbent matrix was coupled with an electrochemical immunoassay analyzer (EIA) and used for the ultra-sensitive detection of the phenyl urea herbicide diuron in real samples. The EIA was fabricated by using carboxylated carbon nanotubes (CNTs) functionalized with a hapten molecule (an amine functionalized diuron derivative). Screen printed electrodes (SPE) were modified with these haptenized CNTs and specific in-house generated anti diuron antibodies were used for bio-interface development. The immunodetection was realized in a competitive electrochemical immunoassay format using alkaline phosphatase labeled secondary anti-IgG antibody. The addition of 1-naphthyl phosphate substrate resulted in the production of an electrochemically active product, 1-naphthol, which was monitored by using differential pulse voltammetry (DPV). The assay exhibited excellent sensitivity and specificity having a dynamic response range of 0.01 pg mL(-1) to 10 μg mL(-1) for diuron with a limit of detection of around 0.1 pg mL(-1) (n = 3) in standard water samples. The micro-cartridge coupled hapten-CNTs modified SPE provided an effective and efficient electrochemical immunoassay for the real-time monitoring of pesticides samples with a very high degree of sensitivity.

  5. Scalability of carbon-nanotube-based thin film transistors for flexible electronic devices manufactured using an all roll-to-roll gravure printing system

    Science.gov (United States)

    Koo, Hyunmo; Lee, Wookyu; Choi, Younchang; Sun, Junfeng; Bak, Jina; Noh, Jinsoo; Subramanian, Vivek; Azuma, Yasuo; Majima, Yutaka; Cho, Gyoujin

    2015-09-01

    To demonstrate that roll-to-roll (R2R) gravure printing is a suitable advanced manufacturing method for flexible thin film transistor (TFT)-based electronic circuits, three different nanomaterial-based inks (silver nanoparticles, BaTiO3 nanoparticles and single-walled carbon nanotubes (SWNTs)) were selected and optimized to enable the realization of fully printed SWNT-based TFTs (SWNT-TFTs) on 150-m-long rolls of 0.25-m-wide poly(ethylene terephthalate) (PET). SWNT-TFTs with 5 different channel lengths, namely, 30, 80, 130, 180, and 230 μm, were fabricated using a printing speed of 8 m/min. These SWNT-TFTs were characterized, and the obtained electrical parameters were related to major mechanical factors such as web tension, registration accuracy, impression roll pressure and printing speed to determine whether these mechanical factors were the sources of the observed device-to-device variations. By utilizing the electrical parameters from the SWNT-TFTs, a Monte Carlo simulation for a 1-bit adder circuit, as a reference, was conducted to demonstrate that functional circuits with reasonable complexity can indeed be manufactured using R2R gravure printing. The simulation results suggest that circuits with complexity, similar to the full adder circuit, can be printed with a 76% circuit yield if threshold voltage (Vth) variations of less than 30% can be maintained.

  6. Probe imaging studies of magnetic susceptibility and permeability for sensitive characterisation of carbonate reservoir rocks

    Science.gov (United States)

    Ivakhnenko, Aleksandr; Bigaliyeva, Akmaral; Dubinin, Vladislav

    2016-04-01

    In this study were disclosed the main principals of identifying petrophysical properties of carbonate reservoirs such as porosity, permeability and magnetic susceptibility. While exploring and developing reservoir there are significant diversity of tasks that can be solved by appropriate knowledge of properties which are listed above. Behavior of fluid flow, distribution of hydrocarbons and other various industrial applications can be solved by measuring areal distribution of these petrophysical parameters. The results demonstrate how magnetic probe and hysteresis measurements correlate with petrophysical parameters in carbonate reservoirs. We made experimental measurements and theoretical calculations of how much magnetic susceptibility depends on the porosity of the rocks and analyzed data with graphics. In theoretical model of the carbonate rocks we considered calcite, dolomite, quartz and combinations of calcite and dolomite, calcite and Fe-dolomite, calcite and quartz, calcite and aragonite with increasing concentrations of the dolomite, Fe-dolomite, quartz and aragonite up to 50% with step of 5%. Here we defined dependence of magnetic susceptibility from the porosity: the higher porosity measurements, the less slope of magnetic susceptibility, consequently mass magnetization is higher for diamagnetic and lower for paramagnetic carbonate rocks, but in the both cases magnetic susceptibility tries to reach zero with increasing of the total porosity. Rock measurements demonstrate that reservoir zones of the low diamagnetic magnetic susceptibility are generally correlated with higher permeability and also porosity distribution. However for different carbonate reservoirs we establish different relationships depending on the complexity of their mineralogy and texture. Application of integral understanding in distribution of permeability, porosity and mineral content in heterogeneous carbonates represented by this approach can be useful tool for carbonate reservoir

  7. Multiwalled carbon nanotube based molecular imprinted polymer for trace determination of 2,4-dichlorophenoxyaceticacid in natural water samples using a potentiometric method

    Science.gov (United States)

    Anirudhan, Thayyath S.; Alexander, Sheeba

    2014-06-01

    A novel potentiometric sensor based on ion imprinted polymer inclusion membrane (IPIM) was prepared from the modification of multiwalled carbon nanotube (MWCNT) based molecularly imprinted polymer for the trace determination of the pesticide 2,4-D (2,4-dichlorophenoxyacetic acid) in natural water samples. MWCNTs are initially functionalized with vinyl groups through nitric acid oxidation along with reacting by allylamine. MWCNT based imprinted polymer (MWCNT-MIP) was synthesized by means of methacrylic acid (MAA) as the monomer, trimethylol propane trimethacrylate (TRIM) as the cross linker, α,α‧-azobisisobutyronitrile (AIBN) as the initiator and 2,4-D an organochlorine pesticide molecule as the template. Organized material was characterized by means of FTIR, XRD and SEM analyses. The sensing membrane was developed by the inclusion of 2,4-D imprinted polymer materials in the polyvinyl chloride (PVC) matrix. The optimization of operational parameters normally used such as amount and nature of plasticizers sensing material, pH and response time was conducted. From the non-imprinted (NIPIM) and imprinted polymer inclusion membrane (IPIM) sensors the response behavior of 2,4-D was compared under optimum conditions. The IPIM sensor responds in the range of 1 × 10-9-1 × 10-5 M and the detection limit was found to be 1.2 × 10-9 M. The stability of MWCNT-IPIM sensor was checked by various methods and it is found to be 3 months and it can be reused many times without losing its sensitivity. For the application of sensor experiments with ground and tap water samples were performed.

  8. Accelerated killing of cancer cells using a multifunctional single-walled carbon nanotube-based system for targeted drug delivery in combination with photothermal therapy

    Directory of Open Access Journals (Sweden)

    Jeyamohan P

    2013-07-01

    Full Text Available Prashanti Jeyamohan, Takashi Hasumura, Yutaka Nagaoka, Yasuhiko Yoshida, Toru Maekawa, D Sakthi Kumar Bio-Nano Electronics Research Centre, Graduate School of Interdisciplinary New Science, Toyo University, Kawagoe, Japan Abstract: The photothermal effect of single-walled carbon nanotubes (SWCNTs in combination with the anticancer drug doxorubicin (DOX for targeting and accelerated destruction of breast cancer cells is demonstrated in this paper. A targeted drug-delivery system was developed for selective killing of breast cancer cells with polyethylene glycol biofunctionalized and DOX-loaded SWCNTs conjugated with folic acid. In our work, in vitro drug-release studies showed that the drug (DOX binds at physiological pH (pH 7.4 and is released only at a lower pH, ie, lysosomal pH (pH 4.0, which is the characteristic pH of the tumor environment. A sustained release of DOX from the SWCNTs was observed for a period of 3 days. SWCNTs have strong optical absorbance in the near-infrared (NIR region. In this special spectral window, biological systems are highly transparent. Our study reports that under laser irradiation at 800 nm, SWCNTs exhibited strong light–heat transfer characteristics. These optical properties of SWCNTs open the way for selective photothermal ablation in cancer therapy. It was also observed that internalization and uptake of folate-conjugated NTs into cancer cells was achieved by a receptor-mediated endocytosis mechanism. Results of the in vitro experiments show that laser was effective in destroying the cancer cells, while sparing the normal cells. When the above laser effect was combined with DOX-conjugated SWCNTs, we found enhanced and accelerated killing of breast cancer cells. Thus, this nanodrug-delivery system, consisting of laser, drug, and SWCNTs, looks to be a promising selective modality with high treatment efficacy and low side effects for cancer therapy. Keywords: cancer, nanotherapy, SWCNTs, targeted drug delivery

  9. Formation of Carbon Nanotube Based Gears: Quantum Chemistry and Molecular Mechanics Study of the Electrophilic Addition of o-Benzyne to Fullerenes, Graphene, and Nanotubes

    Science.gov (United States)

    Jaffe, Richard; Han, Jie; Globus, Al; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    Considerable progress has been made in recent years in chemical functionalization of fullerene molecules. In some cases, the predominant reaction products are different from those obtained (using the same reactants) from polycyclic aromatic hydrocarbons (PAHs). One such example is the cycloaddition of o-benzyne to C60. It is well established that benzyne adds across one of the rings in naphthalene, anthracene and other PAHs forming the [2+4] cycloaddition product (benzobicyclo[2.2.2.]-octatriene with naphthalene and triptycene with anthracene). However, Hoke et al demonstrated that the only reaction path for o-benzyne with C60 leads to the [2+2] cycloaddition product in which benzyne adds across one of the interpentagonal bonds (forming a cyclobutene ring in the process). Either reaction product results in a loss of aromaticity and distortion of the PAH or fullerene substrate, and in a loss of strain in the benzyne. It is not clear, however, why different products are preferred in these cases. In the current paper, we consider the stability of benzyne-nanotube adducts and the ability of Brenner's potential energy model to describe the structure and stability of these adducts. The Brenner potential has been widely used for describing diamondoid and graphitic carbon. Recently it has also been used for molecular mechanics and molecular dynamics simulations of fullerenes and nanotubes. However, it has not been tested for the case of functionalized fullerenes (especially with highly strained geometries). We use the Brenner potential for our companion nanogear simulations and believe that it should be calibrated to insure that those simulations are physically reasonable. In the present work, Density Functional theory (DFT) calculations are used to determine the preferred geometric structures and energetics for this calibration. The DFT method is a kind of ab initio quantum chemistry method for determining the electronic structure of molecules. For a given basis set

  10. Characterization of facies and permeability patterns in carbonate reservoirs based on outcrop analogs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kerans, C.; Lucia, F.J.; Senger, R.K.; Fogg, G.E.; Nance, H.S.; Hovorka, S.D.

    1993-07-01

    The primary objective of this research is to develop methods for better describing the three-dimensional geometry of carbonate reservoir flow units as related to conventional or enhanced recovery of oil. San Andres and Grayburg reservoirs were selected for study because of the 13 Bbbl of remaining mobile oil and 17 Bbbl of residual oil in these reservoirs. The key data base is provided by detailed characterization of geologic facies and rock permeability in reservior-scale outcrops of the Permian San Andres Formation in the Guadalupe Mountains of New Mexico. Emphasis is placed on developing an outcrop analog for San Andres strata that can be used as (1) a guide to interpreting the regional and local geologic framework of the subsurface reservoirs (2) a data source illustrating the scales and patterns of variability of rock-fabric facies and petrophysical properties, particularly in lateral dimension, and on scales that cannot be studied during subsurface reservoir characterization. The research approach taken to achieve these objectives utilizes the integration of geologic description, geostatistical techniques, and reservoir flow simulation experiments. Results from this research show that the spatial distribution of facies relative to the waterflood direction can significantly affect how the reservoir produces. Bypassing of unswept oil occurs due to cross flow of injected water from high permeability zones into lower permeability zones were high permeability zones terminate. An area of unswept oil develops because of the slower advance of the water-injection front in the lower permeability zones. When the injection pattern is reversed, the cross-flow effect changes due to the different arrangements of rock-fabric flow units relative to the flow of injected water, and the sweep efficiency is significantly different. Flow across low-permeability mudstones occurs showing that these layers do not necessarily represent flow barriers.

  11. CO2-induced dissolution of low permeability carbonates. Part I: Characterization and experiments

    Science.gov (United States)

    Smith, Megan M.; Sholokhova, Yelena; Hao, Yue; Carroll, Susan A.

    2013-12-01

    The effect of elevated dissolved CO2 concentrations on compositionally and structurally distinct carbonate sample cores from the Weyburn-Midale CO2-enhanced oil recovery and storage site (Canada) was measured from analysis of 3-D sample characterization and fluid chemistry data from core-flood experiments. Experimental conditions (60 °C; 24.8 MPa confining pressure) and brine composition were chosen to mimic in situ reservoir conditions. Mineralogy and pore space distributions within the eight individual cores were characterized with X-ray computed microtomography and scanning electron microscopy both before and after exposure to brine with 0.5 ⩽ pCO2 ⩽ 3 MPa, while solution chemistry and differential fluid pressures were monitored during experiments. Our experimental study aimed to quantify the relationship between fluid flow, heterogeneity, and reaction specific to carbon storage at the Weyburn-Midale field by integrating characterization imaging, pressure data, and solution chemistry. Through the use of non-invasive microtomographic imaging, a variety of dissolution behaviors were observed, with variable effects on the evolution of solution chemistry and permeability as a result of heterogeneity within these two relatively low permeability carbonate samples. Similar-sized, evenly distributed pores, and steadily advancing dissolution fronts suggested that uniform flow velocities were maintained throughout the duration of the higher permeability “Marly” dolostone core experiments. The development of unstable dissolution fronts and fast pathways occurred in the “Vuggy” sample experiments when fluid velocities varied widely within the sample (as a result of increased pore structure heterogeneity). The overall effect of fast pathway development was to increase bulk permeability values by several orders of magnitude, allowing CO2-acidified fluids to travel through the cores largely unmodified by carbonate mineral reaction, as indicated by a lack of change

  12. Carbon Nanotube-based Supercapacitor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address NASA Goddard Space Flight Center's need for improved cost-effective, low mass and low volume devices or methods to store electrical energy onboard long...

  13. Evolution of permeability and microstructure of tight carbonates due to numerical simulation of calcite dissolution

    Science.gov (United States)

    Miller, K. J.; Vanorio, T.; Keehm, Y.

    2016-12-01

    The current study concerns fundamental controls on fluid flow in tight carbonate rocks during CO2 injection, which has implications for understanding carbonate diagenesis, enhanced hydrocarbon recovery, and CO2 sequestration. Experimental CO2-injection studies find that initial pore geometry is important to the trajectory of permeability-porosity trends. For example, Vanorio et al., [2014] observed over an order of magnitude increase in permeability over <1% increase in connected porosity. The focus of this study is to understand the microstructural origins for these changes and determine - if not porosity - the primary controls on permeability during CO2-injection. Given the grain-scale nature of chemical reactions, we took a digital rock physics approach. A 4.5-mm tight carbonate core was imaged using X-ray micro-computed tomography. Fluid flow was simulated using the Lattice-Boltzmann Method (LBM) [Keehm, 2003]. Dissolution was modeled using a simple, phenomenological approach that coupled the local surface area and velocity to the local reaction rate. Though our model does not include diffusion, it builds upon basic physicochemical principles that underpin transport-limited reaction behavior, namely: (a) the reaction in in non-percolating pathways is fully buffered and (b) the reaction is most rapid in regions where solvent flux is high. The results of our dissolution model mimic experimental CO2-injection: increasing permeability by 300 mD over <1% increase in connected porosity. An analysis of the fluid flux distribution showed that fluid flow tended to channelize, localizing dissolution to paths of least hydraulic resistance. These so-called percolation pathways [Martys and Garboczi, 1992; David, 1993] constituted less than half of the connected pore volume, yet accommodated 90% of the volumetric flux. Interestingly, the percolation porosity exhibited two stages of evolution: (1) decrease at the onset of dissolution until channels were established; (2

  14. Method for the preparation of high surface area high permeability carbons

    Science.gov (United States)

    Lagasse, R.R.; Schroeder, J.L.

    1999-05-11

    A method for preparing carbon materials having high surface area and high macropore volume to provide high permeability. These carbon materials are prepared by dissolving a carbonizable polymer precursor, in a solvent. The solution is cooled to form a gel. The solvent is extracted from the gel by employing a non-solvent for the polymer. The non-solvent is removed by critical point drying in CO{sub 2} at an elevated pressure and temperature or evaporation in a vacuum oven. The dried product is heated in an inert atmosphere in a first heating step to a first temperature and maintained there for a time sufficient to substantially cross-link the polymer material. The cross-linked polymer material is then carbonized in an inert atmosphere. 3 figs.

  15. Method for the preparation of high surface area high permeability carbons

    Energy Technology Data Exchange (ETDEWEB)

    Lagasse, Robert R. (Albuquerque, NM); Schroeder, John L. (Albuquerque, NM)

    1999-05-11

    A method for preparing carbon materials having high surface area and high macropore volume to provide high permeability. These carbon materials are prepared by dissolving a carbonizable polymer precursor, in a solvent. The solution is cooled to form a gel. The solvent is extracted from the gel by employing a non-solvent for the polymer. The non-solvent is removed by critical point drying in CO.sub.2 at an elevated pressure and temperature or evaporation in a vacuum oven. The dried product is heated in an inert atmosphere in a first heating step to a first temperature and maintained there for a time sufficient to substantially cross-link the polymer material. The cross-linked polymer material is then carbonized in an inert atmosphere.

  16. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    Science.gov (United States)

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  17. CO2-induced dissolution of low permeability carbonates. Part II: Numerical modeling of experiments

    Science.gov (United States)

    Hao, Yue; Smith, Megan; Sholokhova, Yelena; Carroll, Susan

    2013-12-01

    We used the 3D continuum-scale reactive transport models to simulate eight core flood experiments for two different carbonate rocks. In these experiments the core samples were reacted with brines equilibrated with pCO2 = 3, 2, 1, 0.5 MPa (Smith et al., 2013 [27]). The carbonate rocks were from specific Marly dolostone and Vuggy limestone flow units at the IEAGHG Weyburn-Midale CO2 Monitoring and Storage Project in south-eastern Saskatchewan, Canada. Initial model porosity, permeability, mineral, and surface area distributions were constructed from micro tomography and microscopy characterization data. We constrained model reaction kinetics and porosity-permeability equations with the experimental data. The experimental data included time-dependent solution chemistry and differential pressure measured across the core, and the initial and final pore space and mineral distribution. Calibration of the model with the experimental data allowed investigation of effects of carbonate reactivity, flow velocity, effective permeability, and time on the development and consequences of stable and unstable dissolution fronts. The continuum scale model captured the evolution of distinct dissolution fronts that developed as a consequence of carbonate mineral dissolution and pore scale transport properties. The results show that initial heterogeneity and porosity contrast control the development of the dissolution fronts in these highly reactive systems. This finding is consistent with linear stability analysis and the known positive feedback between mineral dissolution and fluid flow in carbonate formations. Differences in the carbonate kinetic drivers resulting from the range of pCO2 used in the experiments and the different proportions of more reactive calcite and less reactive dolomite contributed to the development of new pore space, but not to the type of dissolution fronts observed for the two different rock types. The development of the dissolution front was much more

  18. Microbially Induced Carbonate Precipitation: a Novel Grout for Permeability Control in Subsurface Engineering Works

    Science.gov (United States)

    Minto, J. M.; Hingerl, F.; Lunn, R. J.; Benson, S. M.

    2016-12-01

    ContextWe utilise the urea hydrolysing capability of soil bacteria Sporosarcina pasteurii to precipitate CaCO3 in a process termed Microbially Induced Carbonate Precipitation (MICP). MICP injection fluid properties are low particle size and low viscosity giving excellent grout penetrability. The CaCO3 grout has been shown to be effective at reducing permeability in porous and fractured media. MICP has consequently been proposed as an alternative to more traditional cement and chemical grouts, particularly in the fields of radioactive waste disposal and geological sequestration of CO2. This study investigates the role of fluid flow/CaCO3 feedback during precipitation and accelerated dissolution to better understand the longevity of an MICP grout under low pH environmental conditions such as found in a carbon sequestration reservoir. MethodsExperiments were conducted on a single Berea sandstone core in a high pressure core holder to characterise permeability, porosity and multiphase flow behaviour at sequestration reservoir temperature and pressure. Characterisation was carried out before MICP, after MICP, and after accelerated dissolution with hydrochloric acid. At each step the entire core was scanned in a medical x-ray CT scanner to spatially resolve (with a resolution of 0.5x0.5x1mm) the changes in porosity and saturation with CaCO3 precipitation and dissolution. Finally, the dried core was scanned with μ-CT at 30μm (full core) and 10μm (sub-volume) resolutions to investigate structural changes to the Berea at near pore scale. ResultsSix MICP treatment cycles over two days reduced core permeability from 886 mDarcy to 40 mDarcy with a greater reduction in porosity at the inlet. Dissolution with acid restored much of the porosity, but did not restore permeability to the same extent. Preferential flow paths formed during the dissolution step were visible in the first 4mm of the 100mm core, but did not extend further into the core. DiscussionThis study provides

  19. Quantifying porosity and permeability of fractured carbonates and fault rocks in natural groundwater reservoirs

    Science.gov (United States)

    Pirmoradi, Reza; Wolfmayr, Mariella; Bauer, Helene; Decker, Kurt

    2017-04-01

    This study presents porosity and permeability data for a suite of different carbonate rocks from two major groundwater reservoirs in eastern Austria that supply more than 60% of Vienna`s drinking water. Data includes a set of lithologically different, unfractured host rocks, fractured rocks with variable fracture intensities, and fault rocks such as dilation breccias, different cataclasites and dissolution-precipitation fault rocks. Fault rock properties are of particular importance, since fault zones play an important role in the hydrogeology of the reservoirs. The reservoir rocks are exposed at two major alpine karst plateaus in the Northern Calcareous Alps. They comprise of various Triassic calcareous strata of more than 2 km total thickness that reflect facies differentiation since Anisian times. Rocks are multiply deformed resulting in a partly dense network of fractures and faults. Faults differ in scale, fault rock content, and fault rock volumes. Methods used to quantify the porosity and permeability of samples include a standard industry procedure that uses the weight of water saturated samples under hydrostatic uplift and in air to determine the total effective (matrix and fracture) porosity of rocks, measurements on plugs with a fully automated gas porosity- and permeameter using N2 gas infiltrating plugs under a defined confining pressure (Coreval Poro 700 by Vinci technologies), and percolation tests. The latter were conducted in the field along well known fault zones in order to test the differences in fractured rock permeability in situ and on a representative volume, which is not ensured with plug measurements. To calculate hydraulic conductivity by the Darcy equation the measured elapsed time for infiltrating a standard volume of water into a small borehole has been used. In general, undisturbed host rock samples are all of low porosity (average around 1%). The open porosity of the undisturbed rocks belonging to diverse formations vary from 0

  20. Production-log base model for carbonate permeability distribution and steam flood optimization

    Energy Technology Data Exchange (ETDEWEB)

    Ahamed, S.F.; Choudhry, M.A.; Abdulbaqi, J.B. [Kuwait Gulf Oil Co. (Kuwait)

    2008-10-15

    This paper presented a model for the effective management of primary and thermal oil recovery operations in the Wafra Field in Kuwait, where a small huff and puff project was carried out in 1998 to determine if steam injection was a feasible recovery option for the field. The Eocene heavy oil reservoirs of the Wafra Field are carbonate rock admixtures with gypsum and anhydrite. They are the shallowest of the field's productive horizons and exhibit a high degree of fluid flow heterogeneity. The assessment of vertical and lateral permeability variation is a key factor for success of the reservoir development plan. Steam injection began in 2006 in a small scale test (SST) to determine if the innovative technology could produce steam from effluent water and to test the viability of steam injection in carbonate reservoirs. Following the success of the SST, a large scale pilot (LSP) is schedule to start in 2009. It can be used for completion strategies of injectors and producers in steam injection. The model showed that the productivity of the Eocene wells could be correlated with common available logs to develop a log based-permeability model. A series of cross plots for the perforated intervals of high and low productivity wells were constructed to develop a relationship between well productivity and location of log parameters on the plots. A relationship between rock quality, productivity and conventional log parameters was established. It was concluded that the vertical permeability and interwell continuity in the Eocene wells can be used to optimize new well placement for horizontal and vertical infill drilling. The model is also an effective tool to predict the steam injectivity profile to understand the anomalies related to temperature-depth distribution. The model can be used to improve the efficiency of formation heating by optimizing the steam flood process and steam pattern well completion. 16 refs.

  1. Numerical modelling of thermal convection related to fracture permeability in Dinantian carbonate platform, Luttelgeest, the Netherlands

    Science.gov (United States)

    Lipsey, Lindsay; Pluymaekers, Maarten; van Wees, Jan-Diederik; Limberger, Jon; Cloetingh, Sierd

    2016-04-01

    The presence of convective fluid flow in permeable layers can create zones of anomalously high temperature which can be exploited for geothermal energy. Temperature measurements from the Luttelgeest-01 (LTG-01) well in the northern onshore region of the Netherlands indicate variations in the thermal regime that could be indicative of convection. This thermal anomaly coincides with a 600 m interval (4600 - 5200 m) of Dinantian carbonates showing signs of increased fracture permeability of ~60 mD. For the purpose of geothermal energy exploration, it is of interest to know whether or not convection can occur in a particular reservoir, where convection cells are likely to develop and the temperature enhancements in convective upwellings. Three-dimensional numerical simulations provide insight on possible flow and thermal structures within the fractured carbonate interval. The development and number of convection cells is very much a time dependent process. First longitudinal rolls fill the domain, increasing in width until ultimately transforming into a more complex polyhedral structure. The model relaxes into a steady-state five-cell convection pattern. Furthermore, geometric aspects of the carbonate platform itself likely control the shape and location of upwellings. Convective upwellings can create significant temperature enhancements relative to the conductive profile and in agreement with the observations in the Luttelgeest carbonate platform. This enhancement is critically dependent on the aquifer thickness and geothermal gradient. Given a gradient of 39 °C/km and an aquifer thickness of 600 m, a temperature of 203 °C can be obtained at a depth of 4600 m directly above upwelling zones. Contrarily, downwelling zones result in a temperature of 185 °C at the same depth. This demonstrates the strong spatial variability of thermal anomalies in convective fractures aquifers at large depth, which can have a strong effect on exploration opportunity and risk of

  2. Carbon and chlorine isotopologue fractionation of chlorinated hydrocarbons during diffusion in water and low permeability sediments

    Science.gov (United States)

    Wanner, Philipp; Hunkeler, Daniel

    2015-05-01

    To identify reactive processes in diffusion dominated water-saturated systems using compound-specific isotope analysis (CSIA), the effect of the diffusive transport process on isotope ratios needs to be known. This study aims to quantify the magnitude of carbon and chlorine isotopologue fractionation of two chlorinated hydrocarbons (trichloroethene (TCE) and 1,2-dichloroethane (1,2-DCA)) during diffusion in the aqueous phase and to relate for the first time laboratory with field results. Diffusion coefficient ratios in the aqueous phase were experimentally quantified with a modified Stokes diffusion cell. The experiment revealed a significant shift of carbon and chlorine isotopologue ratios of TCE and 1,2-DCA during diffusion. For both TCE and 1,2-DCA, the magnitude of the shift of chlorine isotopologue ratios was larger (TCE: D132/D130 = 0.99963 ± 0.00003; 1,2-DCA: D102/D100 = 0.99939 ± 0.00003) in comparison to carbon isotopologue ratios (TCE: D131/D130 = 0.99978 ± 0.00006; 1,2-DCA: D101/D100 = 0.99977 ± 0.00004), which is consistent with the larger mass difference between stable chlorine compared to carbon isotopes. Determined diffusion coefficients for carbon and chlorine isotopologues of TCE and 1,2-DCA follow an inverse power law form (D ∝m-β) with β < 0.5 revealing that the magnitude of isotopologue fractionation of TCE and 1,2-DCA is lower than in the previously postulated kinetic theory (D ∝m-0.5). To relate laboratory with field results, a water-saturated clay core from a VOC contaminated site was retrieved and subsampled as a function of depth to assess possible shifts in isotopologue ratios during downward diffusion of VOCs into the low permeable clay. Observed small shifts of TCE carbon and chlorine isotopologue ratio profiles were consistent with laboratory determined diffusion coefficient ratios, demonstrated by a 1D-diffusion model. Further 1D-simulations for shorter diffusion periods (5-10 years) than observed in the retrieved clay core

  3. Rapid chloride permeability test for durability study of carbon nanoreinforced mortar

    Science.gov (United States)

    Alafogianni, P.; Dalla, P. T.; Tragazikis, I. K.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The addition of a conductive admixture in a cement-based material could lead to innovative products with multifunctional features. These materials are designed to possess enhanced properties, such as improved mechanical properties, electrical and thermal conductivity, and piezo-electric characteristics. Carbon nanotubes (CNTs) can be used as nano-reinforcement in cement-based materials because of their huge aspect ratio as well as their extremely large specific surface area. For cement-based composites, one of the major types of environmental attack is the chloride ingress, which leads to corrosion of the material and, subsequently, to the reduction of strength and serviceability of the structure. A common method of preventing such deterioration is to avert chlorides from penetrating the structure. The penetration of the concrete by chloride ions is a slow process. It cannot be determined directly in a time frame that would be useful as a quality control measure. Therefore, in order to assess chloride penetration, a test method that accelerates the process is needed, to allow the determination of diffusion values in a reasonable time. In the present research, nanomodified mortars with various concentrations of multi-wall carbon nanotubes (0.2% wt. cement CNTs - 0.6% wt. cement CNTs) were used. The chloride penetration in these materials was monitored according to ASTM C1202 standard. This is known as the Coulomb test or Rapid Chloride Permeability Test (RCPT).

  4. Relative permeabilities of supercritical CO2 and brine in carbon sequestration by a two-phase lattice Boltzmann method

    Science.gov (United States)

    Xie, Jian.-Fei.; He, S.; Zu, Y. Q.; Lamy-Chappuis, B.; Yardley, B. W. D.

    2017-08-01

    In this paper, the migration of supercritical carbon dioxide (CO2) in realistic sandstone rocks under conditions of saline aquifers, with applications to the carbon geological storage, has been investigated by a two-phase lattice Boltzmann method (LBM). Firstly the digital images of sandstone rocks were reproduced utilizing the X-ray computed microtomography (micro-CT), and high resolutions (up to 2.5 μm) were applied to the pore-scale LBM simulations. For the sake of numerical stability, the digital images were "cleaned" by closing the dead holes and removing the suspended particles in sandstone rocks. In addition, the effect of chemical reactions occurred in the carbonation process on the permeability was taken into account. For the wetting brine and non-wetting supercritical CO2 flows, they were treated as the immiscible fluids and were driven by pressure gradients in sandstone rocks. Relative permeabilities of brine and supercritical CO2 in sandstone rocks were estimated. Particularly the dynamic saturation was applied to improve the reliability of the calculations of the relative permeabilities. Moreover, the effects of the viscosity ratio of the two immiscible fluids and the resolution of digital images on the relative permeability were systematically investigated.

  5. Permeability of methane, carbon dioxide, oxygen and nitrogen gases using a composite membrane of polyethersulfone/polyamide 11

    Directory of Open Access Journals (Sweden)

    Bahreini Habib

    2016-12-01

    Full Text Available With the expansion of the refining industry, processing and transportation of gas in Iran, it is of high importance to use new technologies of gas separation. Membrane methods, in particular, separation process through polymeric membranes have been growingly used in recent years. The results of multiple studies show that polyether sulfone compounds have a very good performance in manufacturing polymeric membranes in the area of gas separation. However, efforts are ongoing to improve the permeability and selectivity properties of the membranes. This study investigated separation of methane, carbon dioxide, oxygen and nitrogen gases using composite membranes including, polyethersulfone/ polyamide 11 as the polymer. The membrane was made by molding solution with a composition of 9% to 1% polyethersulfone/polyamide -11. Morphology and structure of the membrane made were examined by Fourier infrared transform (FTIR and scanning electron microscopy (SEM. The level of permeability of the membranes was measured by a fixed volume-variable pressure. Overall results indicated that with 6 time increase of pressure, the amount of permeability of carbon dioxide reduced and then increased. Selectivity for dual gases of carbon dioxide- nitrogen increased by the increase in pressure and maximum amount of pressure is 11/187 at 8 times of increase. The selectivity of carbon dioxide- nitrogen has the greatest value among dual gases.

  6. Seasonal, daily and diel N2 effluxes in permeable carbonate sediments

    Directory of Open Access Journals (Sweden)

    D. T. Maher

    2012-12-01

    Full Text Available Benthic metabolism and inorganic nitrogen and N2 flux rates (denitrification were measured in permeable carbonate sands from Heron Island (Great Barrier Reef. Some of the N2 flux rates were among the highest measured in sediments. All benthic fluxes showed a significant difference between seasons with higher rates in summer and late summer. There was no distinct response of the benthic system to mass coral spawning. Instead, changes in benthic fluxes over 12 days in summer appears to be driven by tidal changes in water depth and associated changes in phytosynthetically active radiation reaching the sediments. Dark N2 fluxes were strongly correlated to benthic oxygen consumption across all sites and seasons (r2 = 0.64; p 2 flux versus benthic oxygen consumption relationship. The lower slope (0.035 was most likely due to high carbon : nitrogen (C : N organic matter from coral reefs, but competition by benthic microalgae for nitrogen, N-fixation or inefficient coupling between respiration and nitrification-denitrification can not be excluded. The steeper slope (0.089 was most likely due to respiration being driven by low C : N phyto-detritus. If the different slopes were driven by the sources of organic matter then global estimates of continental shelf denitrification are probably about right. In contrast, global estimates of continental shelf may be over-estimated if the low slope was due to inefficient coupling between respiration and nitrification-denitrification and also due to reduced N2 effluxes in the light associated with competition by benthic microalgae for nitrogen and N-fixation.

  7. Tomato Seed Coat Permeability to Selected Carbon Nanomaterials and Enhancement of Germination and Seedling Growth.

    Science.gov (United States)

    Ratnikova, Tatsiana A; Podila, Ramakrishna; Rao, Apparao M; Taylor, Alan G

    2015-01-01

    Seed coat permeability was examined using a model that tested the effects of soaking tomato (Solanum lycopersicon) seeds in combination with carbon-based nanomaterials (CBNMs) and ultrasonic irradiation (US). Penetration of seed coats to the embryo by CBNMs, as well as CBNMs effects on seed germination and seedling growth, was examined. Two CBNMs, C60(OH)20 (fullerol) and multiwalled nanotubes (MWNTs), were applied at 50 mg/L, and treatment exposure ranged from 0 to 60 minutes. Bright field, fluorescence, and electron microscopy and micro-Raman spectroscopy provided corroborating evidence that neither CBNM was able to penetrate the seed coat. The restriction of nanomaterial (NM) uptake was attributed to the semipermeable layer located at the innermost layer of the seed coat adjacent to the endosperm. Seed treatments using US at 30 or 60 minutes in the presence of MWNTs physically disrupted the seed coat; however, the integrity of the semipermeable layer was not impaired. The germination percentage and seedling length and weight were enhanced in the presence of MWNTs but were not altered by C60(OH)20. The combined exposure of seeds to NMs and US provided insight into the nanoparticle-seed interaction and may serve as a delivery system for enhancing seed germination and early seedling growth.

  8. A computational assessment of the permeability and salt rejection of carbon nanotube membranes and their application to water desalination.

    Science.gov (United States)

    Thomas, Michael; Corry, Ben

    2016-02-13

    Membranes made from nanomaterials such as nanotubes and graphene have been suggested to have a range of applications in water filtration and desalination, but determining their suitability for these purposes requires an accurate assessment of the properties of these novel materials. In this study, we use molecular dynamics simulations to determine the permeability and salt rejection capabilities for membranes incorporating carbon nanotubes (CNTs) at a range of pore sizes, pressures and concentrations. We include the influence of osmotic gradients and concentration build up and simulate at realistic pressures to improve the reliability of estimated membrane transport properties. We find that salt rejection is highly dependent on the applied hydrostatic pressure, meaning high rejection can be achieved with wider tubes than previously thought; while membrane permeability depends on salt concentration. The ideal size of the CNTs for desalination applications yielding high permeability and high salt rejection is found to be around 1.1 nm diameter. While there are limited energy gains to be achieved in using ultra-permeable CNT membranes in desalination by reverse osmosis, such membranes may allow for smaller plants to be built as is required when size or weight must be minimized. There are diminishing returns in further increasing membrane permeability, so efforts should focus on the fabrication of membranes containing narrow or functionalized CNTs that yield the desired rejection or selection properties rather than trying to optimize pore densities.

  9. Evaluating the Influence of Pore Architecture and Initial Saturation on Wettability and Relative Permeability in Heterogeneous, Shallow-Shelf Carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Byrnes, Alan P.; Bhattacharya, Saibal; Victorine, John; Stalder, Ken

    2007-09-30

    carbonate reservoirs of widely varying moldic pore systems that represent the major of reservoirs in Kansas and are important nationally and worldwide. A goal of the project is to measure wettability, using representative oils from Kansas fields, on a wide range of moldic-porosity lithofacies that are representative of Kansas and midcontinent shallow-shelf carbonate reservoirs. This investigation will discern the relative influence of wetting and pore architecture. In the midcontinent, reservoir water saturations are frequently greater than 'irreducible' because many reservoirs are largely in the capillary transition zone. This can change the imbibition oil-water relative permeability relations. Ignoring wettability and transition-zone relative permeabilities in reservoir modeling can lead to over- and under-prediction of oil recovery and recovery rates, and less effective improved recovery management. A goal of this project is to measure drainage and imbibition oil-water relative permeabilities for a large representative range of lithofacies at differ ent initial water saturations to obtain relations that can be applied everywhere in the reservoir. The practical importance of these relative permeability and wettability models will be demonstrated by using reservoir simulation studies on theoretical/generic and actual reservoir architectures. The project further seeks to evaluate how input of these new models affects reservoir simulation results at varying scales. A principal goal is to obtain data that will allow us to create models that will show how to accurately simulate flow in the shallow-structure, complex carbonate reservoirs that lie in the transition zone. Tasks involved to meet the project objectives include collection and consolidation of available data into a publicly accessible relational digital database and collection of oil and rock samples from carbonate fields around the state (Task 1). Basic properties of these rocks and oils will be measured

  10. Evaluating the Influence of Pore Architecture and Initial Saturation on Wettability and Relative Permeability in Heterogeneous, Shallow-Shelf Carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Byrnes, Alan P.; Bhattacharya, Saibal; Victorine, John; Stalder, Ken

    2007-09-30

    carbonate reservoirs of widely varying moldic pore systems that represent the major of reservoirs in Kansas and are important nationally and worldwide. A goal of the project is to measure wettability, using representative oils from Kansas fields, on a wide range of moldic-porosity lithofacies that are representative of Kansas and midcontinent shallow-shelf carbonate reservoirs. This investigation will discern the relative influence of wetting and pore architecture. In the midcontinent, reservoir water saturations are frequently greater than 'irreducible' because many reservoirs are largely in the capillary transition zone. This can change the imbibition oil-water relative permeability relations. Ignoring wettability and transition-zone relative permeabilities in reservoir modeling can lead to over- and under-prediction of oil recovery and recovery rates, and less effective improved recovery management. A goal of this project is to measure drainage and imbibition oil-water relative permeabilities for a large representative range of lithofacies at differ ent initial water saturations to obtain relations that can be applied everywhere in the reservoir. The practical importance of these relative permeability and wettability models will be demonstrated by using reservoir simulation studies on theoretical/generic and actual reservoir architectures. The project further seeks to evaluate how input of these new models affects reservoir simulation results at varying scales. A principal goal is to obtain data that will allow us to create models that will show how to accurately simulate flow in the shallow-structure, complex carbonate reservoirs that lie in the transition zone. Tasks involved to meet the project objectives include collection and consolidation of available data into a publicly accessible relational digital database and collection of oil and rock samples from carbonate fields around the state (Task 1). Basic properties of these rocks and oils will be measured

  11. Improvement of Carbon Dioxide Sweep Efficiency by Utilization of Microbial Permeability Profile Modification to Reduce the Amount of Oil Bypassed During Carbon Dioxide Flood

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Darrel [Mississippi State Univ., Mississippi State, MS (United States); Brown, Lewis [Mississippi State Univ., Mississippi State, MS (United States); Lynch, F. Leo [Mississippi State Univ., Mississippi State, MS (United States); Kirkland, Brenda L. [Mississippi State Univ., Mississippi State, MS (United States); Collins, Krystal M. [Mississippi State Univ., Mississippi State, MS (United States); Funderburk, William K. [Mississippi State Univ., Mississippi State, MS (United States)

    2010-12-31

    The objective of this project was to couple microbial permeability profile modification (MPPM), with carbon dioxide flooding to improve oil recovery from the Upper Cretaceous Little Creek Oil Field situated in Lincoln and Pike counties, MS. This study determined that MPPM technology, which improves production by utilizing environmentally friendly nutrient solutions to simulate the growth of the indigenous microflora in the most permeable zones of the reservoir thus diverting production to less permeable, previously unswept zones, increased oil production without interfering with the carbon dioxide flooding operation. Laboratory tests determined that no microorganisms were produced in formation waters, but were present in cores. Perhaps the single most significant contribution of this study is the demonstration that microorganisms are active at a formation temperature of 115°C (239°F) by using a specially designed culturing device. Laboratory tests were employed to simulate the MPPM process by demonstrating that microorganisms could be activated with the resulting production of oil in coreflood tests performed in the presence of carbon dioxide at 66°C (the highest temperature that could be employed in the coreflood facility). Geological assessment determined significant heterogeneity in the Eutaw Formation, and documented relatively thin, variably-lithified, well-laminated sandstone interbedded with heavily-bioturbated, clay-rich sandstone and shale. Live core samples of the Upper Cretaceous Eutaw Formation from the Heidelberg Field, MS were quantitatively assessed using SEM, and showed that during MPPM permeability modification occurs ubiquitously within pore and throat spaces of 10-20 μm diameter. Testing of the MPPM procedure in the Little Creek Field showed a significant increase in production occurred in two of the five production test wells; furthermore, the decline curve in each of the production wells became noticeably less steep. This project greatly

  12. An Evaluation of Subsurface Microbial Activity Conditional to Subsurface Temperature, Porosity, and Permeability at North American Carbon Sequestration Sites

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, B. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Mordensky, S. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Verba, Circe [National Energy Technology Lab. (NETL), Albany, OR (United States); Rabjohns, K. [Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); National Energy Technology Lab. (NETL), Albany, OR (United States); Colwell, F. [National Energy Technology Lab. (NETL), Albany, OR (United States); Oregon State Univ., Corvallis, OR (United States). College of Earth, Ocean, and Atmospheric Sciences

    2016-06-21

    Several nations, including the United States, recognize global climate change as a force transforming the global ecosphere. Carbon dioxide (CO2) is a greenhouse gas that contributes to the evolving climate. Reduction of atmospheric CO2 levels is a goal for many nations and carbon sequestration which traps CO2 in the Earth’s subsurface is one method to reduce atmospheric CO2 levels. Among the variables that must be considered in developing this technology to a national scale is microbial activity. Microbial activity or biomass can change rock permeability, alter artificial seals around boreholes, and play a key role in biogeochemistry and accordingly may determine how CO2 is sequestered underground. Certain physical parameters of a reservoir found in literature (e.g., temperature, porosity, and permeability) may indicate whether a reservoir can host microbial communities. In order to estimate which subsurface formations may host microbes, this report examines the subsurface temperature, porosity, and permeability of underground rock formations that have high potential to be targeted for CO2 sequestration. Of the 268 North American wellbore locations from the National Carbon Sequestration Database (NATCARB; National Energy and Technology Laboratory, 2015) and 35 sites from Nelson and Kibler (2003), 96 sequestration sites contain temperature data. Of these 96 sites, 36 sites have temperatures that would be favorable for microbial survival, 48 sites have mixed conditions for supporting microbial populations, and 11 sites would appear to be unfavorable to support microbial populations. Future studies of microbe viability would benefit from a larger database with more formation parameters (e.g. mineralogy, structure, and groundwater chemistry), which would help to increase understanding of where CO2 sequestration could be most efficiently implemented.

  13. Reactive Flow Experiments to Characterize Porosity and Permeability Evolution during CO2 Transport in Weyburn-Midale Carbonate Rocks

    Science.gov (United States)

    Smith, M. M.; Sholokhova, Y.; Hao, Y.; Carroll, S.

    2011-12-01

    We investigated the relative effects of CO2-induced disequilibrium and pre-existing mineralogy and void space heterogeneity on permeability development in carbonate core samples from the Weyburn-Midale hydrocarbon reservoir (Canada). The aim of our work was to use detailed pre- and post-experimental x-ray computed tomography (XCMT) imaging, as well as geochemical data, to constrain reactive transport models that predict the evolution of pore space and permeability for geologic storage of CO2 in enhanced oil recovery (EOR) fields. A total of nine core-flooding experiments were completed, using three distinct rock types (tight limestone, porous dolostone, and evaporite caprock) to represent the range of natural reservoir physical and chemical heterogeneity. Experiments were conducted under 25 MPa confining pressure, 60C temperature, and elevated salinity conditions, with pCO2 levels from 0.5-3 MPa. The coupling of intensive characterization with pressure/permeability and solution chemistry measurements provided powerful tools for interpreting and correlating mineral reactions and stability with pre-existing features and heterogeneities. We observed increased carbonate mass transfer rates, stable dissolution fronts, and greater volumes of dissolved minerals for cores with relatively homogeneous pore networks. Samples with more heterogeneous pore size distributions responded with variable mass transfer rates and development of fast transport pathways in regions with preexisting fractures. We infer that the breakthrough of these preferential fluid pathways leads to reductions in available reactive surface area, allowing undersaturated fluids to be transported through the cores despite relatively fast carbonate dissolution kinetics.

  14. Simulation of Carbon Nanotube-based Heat Dissipation of High Power LED Lamp%碳纳米管在大功率LED灯具中的散热模拟

    Institute of Scientific and Technical Information of China (English)

    黄海波; 王元樟; 李爱玉; 程再军; 刘正达

    2016-01-01

    A finite element simulation of carbon nanotubes function in high power LED thermal management was conducted using FloEFD software in order to find out how carbon nanotube functions in heat dissipation of high power electronic devices. A simplified heat conduction model of multi⁃walled carbon nanotube arrays was established, and effective thermal conductivity of the multi⁃walled carbon nanotube array calculated based on the model. The steady⁃state temperature distributions of the LED with different thermal interface materials were then compared. It is shown that carbon nanotube arrays can greatly improve the thermal management performance of lamps, and that carbon nanotube polyurethane composite coating can greatly reduce the junction temperature.%用基于有限元方法的FloEFD软件,对碳纳米管在大功率发光二极管( LED)热管理中的应用进行模拟。建立起一个多壁碳纳米管阵列热传导的简化模型,据此模型对多壁碳纳米管阵列的等效热导率进行了计算。通过对采用不同热界面材料后LED灯具的稳态温度场分布的比较,发现碳纳米管阵列能大大提高灯具的热管理性能。模拟结果显示,采用聚氨酯碳纳米管复合材料涂层能大大降低结温。

  15. Rapid prototyping of nanotube-based devices using topology-optimized microgrippers

    DEFF Research Database (Denmark)

    Sardan, Özlem; Eichhorn, Volkmar; Petersen, D.H.

    2008-01-01

    Nanorobotic handling of carbon nanotubes (CNTs) using microgrippers is one of the most promising approaches for the rapid characterization of the CNTs and also for the assembly of prototypic nanotube-based devices. In this paper, we present pick-and-place nanomanipulation of multi-walled CNTs...... as well as close. Topology optimization leads to a 10-100 times improvement of the gripping force compared to conventional designs of similar size. Furthermore, we improved our nanorobotic system to offer more degrees of freedom. TEM investigation of the CNTs shows that the multi-walled tubes are coated...

  16. Effect of weave tightness and structure on the in-plane and through-plane air permeability of woven carbon fibers for gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Caston, Terry B.; Murphy, Andrew R.; Harris, Tequila A.L. [Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-01-15

    In this study, woven gas diffusion layers (GDLs) with varying weave type and tightness are investigated. Plain and twill weave patterns were manufactured in-house. The in-plane and through-plane air permeability of the woven samples were tested, and mercury intrusion porosimetry (MIP) tests were performed to study the pore structure. It was found that the twill weave has a higher permeability than the plain weave, which is consistent with literature. Like non-woven carbon papers, woven GDLs have higher in-plane permeability than through-plane permeability; however it has been shown that it is possible to manufacture a GDL with higher through-plane permeability than in-plane permeability. It was also concluded that the percentage of macropores in the weave is the driving factor in determining the through-plane air permeability. This work lays the groundwork for future studies to attempt to characterize the relationship between the weave structure and the air permeability in woven GDLs. (author)

  17. Comprehensive Evaluation Method for the Low Permeability Carbonate Reservoir%低渗碳酸盐岩油藏储层综合评价方法

    Institute of Scientific and Technical Information of China (English)

    杨正明; 蒋帅; 张亚蒲; 朱光亚; 郭和坤

    2016-01-01

    The low permeability carbonate reservoir is an important oil reservoir type developed overseas by PetroChina. Due to the complex structures of microscopic pore-throat and apparent differences with low permeability sandstone reservoir,it is necessary to research on the evaluation method of the low permeability carbonate reservoirs. Based on the test of 550 low permeability carbonate cores,the mainstream throat radius,the movable fluid percentage,the threshold gradient and the crude oil viscosity are determined to be the four paramenters to evaluate the low permeability carbonate reservoir. The research shows that the throat radius changes largely at the low permeability carbonate cores with different permeability and the full diameter cores′gas permeability has a semi-logarithmic relationship with the percentage of movable fluid. Besides,under the condition of same permeability,most throat radius of low permeability carbonate cores is smaller than that of low permeability sandstone, while the movable fluid percentage of carbonate is larger than that of sandstone which is in agreement with the reservoir property. Based on the results,four-factor classification of low permeability carbonate reservoir is put forward and the comprehensive evaluation method is hence introduced,which is successfully applied to the evaluation of the layers in a typical low permeability carbonate reservoir overseas.%低渗碳酸盐岩油藏是中国石油在海外开发的重要油藏类型,该油藏储层微观孔喉结构复杂,与低渗砂岩油藏有明显的差异,急需进行低渗碳酸盐岩油藏储层评价方面的研究工作。在550块低渗碳酸盐岩岩芯测试的基础上,提出了用主流喉道半径、启动压力梯度、可动流体百分数和原油黏度4个参数作为低渗碳酸盐岩油藏储层评价参数。研究表明:不同渗透率的低渗碳酸盐岩岩芯,其喉道半径分布差异显著,全直径岩样的气测渗透率和可动流

  18. Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-12-15

    Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

  19. Carbon dioxide transport in alligator blood and its erythrocyte permeability to anions and water

    DEFF Research Database (Denmark)

    Jensen, F B; Wang, T; Jones, D R

    1998-01-01

    Deoxygenation of alligator red blood cells (RBCs) caused binding of two HCO3- equivalents per hemoglobin (Hb) tetramer at physiological pH. At lowered pH, some HCO3- binding also occurred to oxygenated Hb. The erythrocytic total CO2 content was large, and Hb-bound HCO3-, free HCO3-, and carbamate......+ binding. Erythrocyte volume, plasma pH, and plasma HCO3- concentration also varied little with the degree of oxygenation. Diffusional water permeability was higher in oxygenated than deoxygenated RBCs. The RBCs have rapid band 3-mediated Cl- and HCO3- transport, which was not affected by degree...... of oxygenation, but net fluxes of Cl- and HCO3- via the anion exchanger are small during blood circulation at rest. Most of the CO2 taken up into the blood as it flows through tissue capillaries is carried within the erythrocytes as Hb-bound HCO3- until CO2 is excreted when blood flows through pulmonary...

  20. Nanotube-Based Chemical and Biomolecular Sensors

    Institute of Scientific and Technical Information of China (English)

    J.Koh; B.Kim; S.Hong; H.Lim; H.C.Choi

    2008-01-01

    We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomolecular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) process or "surface programmed assembly" method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.

  1. Porosity and Permeability Development of the Deep-Water Late-Oligocene Carbonate Debris Reservoir in the Surroundings of the Paternoster Platform, South Makassar Basin, Indonesia

    Directory of Open Access Journals (Sweden)

    Gadjah E. Pireno

    2015-12-01

    Full Text Available The discovery of gas within the carbonate debris reservoir of the late Oligocene Berai formation near the Paternoster Platform, South Makassar Basin, is a new exploration play in Indonesia. The carbonate was deposited in a deep-water environment and is a good example of a less well known carbonate play type. The carbonate debris reservoir in this area consists of re-deposited carbonate, originally located on a large carbonate platform that has been eroded, abraded and transported to the deep-water sub-basin. The limestone clasts range from pebble-size to boulders within a matrix of micrite and fine abraded bioclasts. This carbonate debris can be divided into clast-supported facies and matrix-supported facies. The matrix-supported facies have much better porosity and permeability than the clast-supported facies. Porosity in both the transported clasts and the matrix is generally mouldic and vuggy, resulting mostly from dissolution of foraminifera and other bioclastics after transportation. In the matrix intercrystal porosity has developed. The porosity and permeability development of this deep-water carbonate debris was controlled by a deep-burial diagenetic process contributed by the bathyal shales de-watering from the Lower Berai shales beneath the carbonate reservoir and the Lower Warukin shales above the carbonate reservoir during the burial process.

  2. Simultaneous effects of single wall carbon nanotube and effective variable viscosity for peristaltic flow through annulus having permeable walls

    Science.gov (United States)

    Shahzadi, Iqra; Nadeem, S.; Rabiei, Faranak

    The current article deals with the combine effects of single wall carbon nanotubes and effective viscosity for the peristaltic flow of nanofluid through annulus. The nature of the walls is assumed to be permeable. The present theoretical model can be considered as mathematical representation to the motion of conductive physiological fluids in the existence of the endoscope tube which has many biomedical applications such as drug delivery system. The outer tube has a wave of sinusoidal nature that is travelling along its walls while the inner tube is rigid and uniform. Lubrication approach is used for the considered analysis. An empirical relation for the effective variable viscosity of nanofluid is proposed here interestingly. The viscosity of nanofluid is the function of radial distance and the concentration of nanoparticles. Exact solution for the resulting system of equations is displayed for various quantities of interest. The outcomes show that the maximum velocity of SWCNT-blood nanofluid enhances for larger values of viscosity parameter. The pressure gradient in the more extensive part of the annulus is likewise found to increase as a function of variable viscosity parameter. The size of the trapped bolus is also influenced by variable viscosity parameter. The present examination also revealed that the carbon nanotubes have many applications related to biomedicine.

  3. Use of 3D Seismic Azimuthal Iso-Frequency Volumes for the Detection and Characterization of High Porosity/Permeability Zones in Carbonate Reservoirs

    Science.gov (United States)

    Toelle, Brian E.

    Among the most important properties controlling the production from conventional oil and gas reservoirs is the distribution of porosity and permeability within the producing geologic formation. The geometry of the pore space within these reservoirs, and the permeability associated with this pore space geometry, impacts not only where production can occur and at what flow rates but can also have significant influence on many other rock properties. Zones of high matrix porosity can result in an isotropic response for certain reservoir properties whereas aligned porosity/permeability, such as open, natural fracture trends, have been shown to result in reservoirs being anisotropic in many properties. The ability to identify zones within a subsurface reservoir where porosity/permeability is significantly higher and to characterize them according to their geometries would be of great significance when planning where new boreholes, particularly horizontal boreholes, should be drilled. The detection and characterization of these high porosity/permeability zones using their isotropic and anisotropic responses may be possible through the analysis of azimuthal (also referred to as azimuth-limited) 3D seismic volumes. During this study the porosity/permeability systems of a carbonate, pinnacle reef within the northern Michigan Basin undergoing enhanced oil recovery were investigated using selected seismic attributes extracted from azimuthal 3D seismic volumes. Based on the response of these seismic attributes an interpretation of the geometry of the porosity/permeability system within the reef was made. This interpretation was supported by well data that had been obtained during the primary production phase of the field. Additionally, 4D seismic data, obtained as part of the CO2 based EOR project, supported reservoir simulation results that were based on the porosity/permeability interpretation.

  4. Comparative study of all-printed polyimide humidity sensors with single- and multiwalled carbon nanotube gas-permeable top electrodes

    Science.gov (United States)

    Itoh, Eiji; Yuan, Zihan

    2017-05-01

    We have developed printed capacitive humidity sensors with highly gas permeable carbon nanotube top electrodes using solution techniques. The hydrophobic, porous multiwalled carbon nanotube (MWCNT) network was suitable for gas permeation, and the response of the capacitive humidity sensors was faster than that of a device with a single-walled carbon nanotube (SWCNT) top electrode. The newly developed measurement system consisting of a small measurement chamber, a computer-controlled high-speed solenoid valve, and a mass-flow controller enabled us to vary the ambient relative humidity within 0.1 s. A comparative study of the devices consisting of a 1.1-µm-thick partially fluorinated polyimide dielectric layer and an MWCNT or SWCNT top electrode revealed that the rise time (humidification process) of the device with MWCNTs (0.49 s) in the transient measurement was almost 3 times shorter than that with SWCNTs (1.48 s) owing to the hydrophobic surface of the MWCNTs. A much larger difference was observed during the drying process (recovery time) probably owing to the hydrophilic parts of the SWCNT surface. It was revealed that the response time was almost proportional to the square of the thickness of the polyimide dielectric layer, d, and the sensitivity was inversely proportional to d. The rise time decreased to 0.15 s and a sensitivity per unit area of 12.1 pF %RH-1 cm-2 was obtained in a device with 0.6-µm-thick polyimide and MWCNT top electrodes. This value is suitable for use in high-speed humidity sensors to realize a real-time humidity and breath-sensing measurement system.

  5. Multiscale modeling and simulation of nanotube-based torsional oscillators

    Directory of Open Access Journals (Sweden)

    Xiao Shaoping

    2006-01-01

    Full Text Available AbstractIn this paper, we propose the first numerical study of nanotube-based torsional oscillators via developing a new multiscale model. The edge-to-edge technique was employed in this multiscale method to couple the molecular model, i.e., nanotubes, and the continuum model, i.e., the metal paddle. Without losing accuracy, the metal paddle was treated as the rigid body in the continuum model. Torsional oscillators containing (10,0 nanotubes were mainly studied. We considered various initial angles of twist to depict linear/nonlinear characteristics of torsional oscillators. Furthermore, effects of vacancy defects and temperature on mechanisms of nanotube-based torsional oscillators were discussed.

  6. Carbon nanotubes based nafion composite membranes for fuel cell applications

    CSIR Research Space (South Africa)

    Cele, NP

    2009-01-01

    Full Text Available surface oxidation as well as functionalisation in composite membranes was investigated by focussing on three aspects: thermo-mechanical stability, thermal degradation and proton conductivity. The oCNTs-containing Nafion composite membrane exhibited...

  7. Carbon Nanotube-Based Adsorbents for Volatile Air Contaminants Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In completing the Phase I SBIR, Agave BioSystems and the Universities Space Research Association, have successfully demonstrated proof of concept for the use of...

  8. Carbon nanotube based VLSI interconnects analysis and design

    CERN Document Server

    Kaushik, Brajesh Kumar

    2015-01-01

    The brief primarily focuses on the performance analysis of CNT based interconnects in current research scenario. Different CNT structures are modeled on the basis of transmission line theory. Performance comparison for different CNT structures illustrates that CNTs are more promising than Cu or other materials used in global VLSI interconnects. The brief is organized into five chapters which mainly discuss: (1) an overview of current research scenario and basics of interconnects; (2) unique crystal structures and the basics of physical properties of CNTs, and the production, purification and applications of CNTs; (3) a brief technical review, the geometry and equivalent RLC parameters for different single and bundled CNT structures; (4) a comparative analysis of crosstalk and delay for different single and bundled CNT structures; and (5) various unique mixed CNT bundle structures and their equivalent electrical models.

  9. Carbon Nanotube-Based Separation Columns for Microchip Electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Delacourt, B.; Kutter, Jörg Peter

    2015-01-01

    Fabrication of the stationary phase for microchip chromatography is most often done by packing of the individual separation channel after fabrication of the microfluidic chip, which is a very time-consuming and costly process (Kutter. J Chromatogr A 1221:72–82, 2012). Here, we describe in detail...

  10. Study of the interactions bacteria - phenanthrene - activated carbon for the preparation of a permeable reactive barrier; Etude des interactions bacteries - phenanthrene - charbon en vue de l'elaboration d'une barriere permeable reactive

    Energy Technology Data Exchange (ETDEWEB)

    Leglize, P.

    2004-12-01

    Permeable Reactive Barrier (PRB) is a new way for the remediation of contaminated groundwater, but up to now Polycyclic Aromatic Hydrocarbons (PAHs) were rarely considered. We investigated PAH - bacteria - materials interactions in order to validate the feasibility of PRB for PAH contamination. PHE Adsorption/desorption kinetics onto different materials, activated carbons (CA), pozzolana (Pz) and pozzolana coated with heavy fuel (PzF), were investigated. PHE biodegradation were performed on batch using PAH degrading bacteria and the PRB materials. CA was a good media for PRB process: Phenanthrene sorption capacity is 100 to 10000 fold higher than PzF and Pz. Phenanthrene mineralization with CA was higher than without material. Bacterial properties affected PHE biodegradation. Bio-film production improved PHE biodegradation by PAH degrading bacteria. Column studies showed that inoculation of the column improved its efficiency: adsorbed PHE degradation and increased retardation of PHE. (author)

  11. Notional Permeability

    NARCIS (Netherlands)

    Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.

    2012-01-01

    Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath

  12. Study on permeability of gestodene from polytrimethylene carbonate%聚三亚甲基碳酸酯对孕二烯酮透过性的影响

    Institute of Scientific and Technical Information of China (English)

    刘丹华; 陈大为; 杨丹; 张翀; 关艳敏; 郭晶

    2011-01-01

    目的 考察聚三亚甲基碳酸酯对孕二烯酮的透过性,以期为避孕及其他埋植剂、透皮制剂的制备提供一定的参考依据.方法 采用溶剂自然挥散法制备薄膜,双隔室静态小室法进行透过实验,紫外-可见分光光度法测定孕二烯酮的透过量.结果 聚三亚甲基碳酸酯成膜性能良好,24h孕二烯酮的透过量接近或大于4.425×10-6 g·cm-2.结论 通过控制分子质量、剂型和载药面积,聚三亚甲基碳酸酯可作为降解型避孕药物控释系统的载体.%Objective To investigate the permeability of gestodene from polytrimethylene carbonate and consequently to provide a reference for the preparation of implants for contraception, other implants and trans-dermal preparations. Methods A natural solvent evaporation method was adopted for preparing the film, a double-compartment static chamber method was used for carrying out the permeability experiment, and a UV-visible absorbance method was used for measuring the permeating amount of gestodene. Results Polytrimethylene carbonate had a good film-forming property, and the amount of gestodene permeating from the film was close to or greater than 4.425 x 10 "6 g-cm"2 after 24 hours permeability experiment. Conclusions By controlling molecular weight,formulation and drug-carrying area,polytrimethylene carbonate can be used as a carrier of degradable controlled-release delivery system for contraceptive drugs.

  13. Design and Analysis of Nanotube-Based Memory Cells

    Directory of Open Access Journals (Sweden)

    Andersen David

    2008-01-01

    Full Text Available Abstract In this paper, we proposed a nanoelectromechanical design as memory cells. A simple design contains a double-walled nanotube-based oscillator. Atomistic materials are deposed on the outer nanotube as electrodes. Once the WRITE voltages are applied on electrodes, the induced electromagnetic force can overcome the interlayer friction between the inner and outer tubes so that the oscillator can provide stable oscillations. The READ voltages are employed to indicate logic 0/1 states based on the position of the inner tube. A new continuum modeling is developed in this paper to analyze large models of the proposed nanoelectromechanical design. Our simulations demonstrate the mechanisms of the proposed design as both static and dynamic random memory cells.

  14. Permeability reduction produced by grain reorganization and accumulation of exsolved CO2 during geologic carbon sequestration: a new CO2 trapping mechanism.

    Science.gov (United States)

    Luhmann, Andrew J; Kong, Xiang-Zhao; Tutolo, Benjamin M; Ding, Kang; Saar, Martin O; Seyfried, William E

    2013-01-01

    Carbon sequestration experiments were conducted on uncemented sediment and lithified rock from the Eau Claire Formation, which consisted primarily of K-feldspar and quartz. Cores were heated to accentuate reactivity between fluid and mineral grains and to force CO(2) exsolution. Measured permeability of one sediment core ultimately reduced by 4 orders of magnitude as it was incrementally heated from 21 to 150 °C. Water-rock interaction produced some alteration, yielding sub-μm clay precipitation on K-feldspar grains in the core's upstream end. Experimental results also revealed abundant newly formed pore space in regions of the core, and in some cases pores that were several times larger than the average grain size of the sediment. These large pores likely formed from elevated localized pressure caused by rapid CO(2) exsolution within the core and/or an accumulating CO(2) phase capable of pushing out surrounding sediment. CO(2) filled the pores and blocked flow pathways. Comparison with a similar experiment using a solid arkose core indicates that CO(2) accumulation and grain reorganization mainly contributed to permeability reduction during the heated sediment core experiment. This suggests that CO(2) injection into sediments may store more CO(2) and cause additional permeability reduction than is possible in lithified rock due to grain reorganization.

  15. Nitrogen-doped MoS2/carbon as highly oxygen-permeable and stable catalysts for oxygen reduction reaction in microbial fuel cells

    Science.gov (United States)

    Hao, Liang; Yu, Jia; Xu, Xin; Yang, Liu; Xing, Zipeng; Dai, Ying; Sun, Ye; Zou, Jinlong

    2017-01-01

    Developing non-noble metal catalysts with high oxygen-permeability and activity for oxygen reduction reaction (ORR) is crucial for microbial fuel cells (MFCs). In this study, nitrogen-doped molybdenum disulfide/carbon (N-MoS2/C) is prepared using melamine as nitrogen and carbon sources. Ammonium molybdate, thiourea and Pluronic F127 are used as Mo source, S source and surfactant, respectively. Mo-S-melamine complex precursor is obtained through the evaporation-induced self-assembly route, which is then carbonized at 800, 900 and 1000 °C to fabricate N-MoS2/C. Defect-rich N-MoS2/C has a large number of exposed active sites and a high oxygen permeability. N-MoS2/C (900 °C) with regular honeycomb structure shows the maximum power density of 0.815 W m-2, which is far higher than that of Pt/C (0.520 W m-2) and only has a decline of 1.23% after 1800 h operation in MFCs. Four-electron (4e-) reduction of O2 is the main ORR pathway for N-MoS2/C (900 °C), attributing to the efficient permeation, adsorption, activation and reduction of O2 on the active sites. The synergy among abundant defects, N-species (pyridinic N, graphitic N and Mo-Nx) and high conductivity contributes to the promising ORR activity. This simple synthetic route of N-doped metal sulfides/carbon composites displays a new prospect for preparation of ORR catalyst.

  16. DE-SC0004118 (Wong & Lindquist). Final Report: Changes of Porosity, Permeability and Mechanical Strength Induced by Carbon Dioxide Sequestration.

    Energy Technology Data Exchange (ETDEWEB)

    WONG, TENG-FONG; Lindquist, Brent

    2014-09-22

    In the context of CO{sub 2} sequestration, the overall objective of this project is to conduct a systematic investigation of how the flow of the acidic, CO{sub 2} saturated, single phase component of the injected/sequestered fluid changes the microstructure, permeability and strength of sedimentary rocks, specifically limestone and sandstone samples. Hydromechanical experiments, microstructural observations and theoretical modeling on multiple scales were conducted.

  17. Nanotube-based source of charges for experiments with solid helium at low temperatures

    Science.gov (United States)

    Borisenko, D. N.; Walmsley, P. M.; Golov, A. I.; Kolesnikov, N. N.; Kotov, Yu. V.; Levchenko, A. A.; Mezhov-Deglin, L. P.; Fear, M. J.

    2015-07-01

    Methods of preparation of the field-emission sources of charges from carbon nanotubes suitable for study of injected charges in solid helium at low temperatures T nanotubes onto a flat copper substrate or by mechanical rubbing of nanotubes into porous metal surface. The test study of the voltage-current characteristics of a diode cell with the nanotube source in superfluid He II have shown that at voltages above 120 V one can observe a relatively large current I ≥ 10-13 A of negative charges in liquid helium. The field and temperature dependences of positive and negative currents in solid 4He were studied in samples grown by the blocked capillary technique. Usage of the nanotube based source of injected charges had permitted us for the first time to observe motion of the positive charges in solid helium at temperatures below 0.1 K. The current-voltage dependence could be described by a power law I ˜Uα , with the value of the exponent α ≫ 2, much higher than what one would expect for the regime of space charge limited currents.

  18. Multiscale modeling of graphene- and nanotube-based reinforced polymer nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Montazeri, A. [Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Rafii-Tabar, H., E-mail: rafii-tabar@nano.ipm.ac.ir [Computational Physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); Department of Medical Physics and Biomedical Engineering, and Research Centre for Medical Nanotechnology and Tissue Engineering, Shahid Beheshti University of Medical Sciences, Evin, Tehran (Iran, Islamic Republic of)

    2011-10-31

    A combination of molecular dynamics, molecular structural mechanics, and finite element method is employed to compute the elastic constants of a polymeric nanocomposite embedded with graphene sheets, and carbon nanotubes. The model is first applied to study the effect of inclusion of graphene sheets on the Young modulus of the composite. To explore the significance of the nanofiller geometry, the elastic constants of nanotube-based and graphene-based polymer composites are computed under identical conditions. The reinforcement role of these nanofillers is also investigated in transverse directions. Moreover, the dependence of the nanocomposite's axial Young modulus on the presence of ripples on the surface of the embedded graphene sheets, due to thermal fluctuations, is examined via MD simulations. Finally, we have also studied the effect of sliding motion of graphene layers on the elastic constants of the nanocomposite. -- Highlights: → A hierarchical MD/FEM multiscale model of nanocomposites is developed. → At low nanofiller content, graphene layers perform significantly better than CNTs. → Ripples in the graphene layers reduce the Young modulus of nanocomposites. → The elastic moduli is considerably affected by the shear of graphene layers.

  19. Notional Permeability

    OpenAIRE

    Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; van der Meer, J W

    2012-01-01

    Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath the armour layer has the ability to dissipate more wave energy and therefore requires less weight of the armour layer. The influence of this parameter is thus very important in economic sense. Up u...

  20. A High-Flux, Flexible Membrane with Parylene-encapsulated Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Park, H G; In, J; Kim, S; Fornasiero, F; Holt, J K; Grigoropoulos, C P; Noy, A; Bakajin, O

    2008-03-14

    We present fabrication and characterization of a membrane based on carbon nanotubes (CNTs) and parylene. Carbon nanotubes have shown orders of magnitude enhancement in gas and water permeability compared to estimates generated by conventional theories [1, 2]. Large area membranes that exhibit flux enhancement characteristics of carbon nanotubes may provide an economical solution to a variety of technologies including water desalination [3] and gas sequestration [4]. We report a novel method of making carbon nanotube-based, robust membranes with large areas. A vertically aligned dense carbon nanotube array is infiltrated with parylene. Parylene polymer creates a pinhole free transparent film by exhibiting high surface conformity and excellent crevice penetration. Using this moisture-, chemical- and solvent-resistant polymer creates carbon nanotube membranes that promise to exhibit high stability and biocompatibility. CNT membranes are formed by releasing a free-standing film that consists of parylene-infiltrated CNTs, followed by CNT uncapping on both sides of the composite material. Thus fabricated membranes show flexibility and ductility due to the parylene matrix material, as well as high permeability attributed to embedded carbon nanotubes. These membranes have a potential for applications that may require high flux, flexibility and durability.

  1. Earthquake-enhanced permeability - evidence from carbon dioxide release following the ML 3.5 earthquake in West Bohemia

    Science.gov (United States)

    Fischer, T.; Matyska, C.; Heinicke, J.

    2017-02-01

    The West Bohemia/Vogtland region is characterized by earthquake swarm activity and degassing of CO2 of mantle origin. A fast increase of CO2 flow rate was observed 4 days after a ML 3.5 earthquake in May 2014 in the Hartoušov mofette, 9 km from the epicentres. During the subsequent 150 days the flow reached sixfold of the original level, and has been slowly decaying until present. Similar behavior was observed during and after the swarm in 2008 pointing to a fault-valve mechanism in long-term. Here, we present the results of simulation of gas flow in a two dimensional model of Earth's crust composed of a sealing layer at the hypocentre depth which is penetrated by the earthquake fault and releases fluid from a relatively low-permeability lower crust. This simple model is capable of explaining the observations, including the short travel time of the flow pulse from 8 km depth to the surface, long-term flow increase and its subsequent slow decay. Our model is consistent with other analyse of the 2014 aftershocks which attributes their anomalous character to exponentially decreasing external fluid force. Our observations and model hence track the fluid pressure pulse from depth where it was responsible for aftershocks triggering to the surface where a significant long-term increase of CO2 flow started 4 days later.

  2. Photon-impenetrable, electron-permeable: the carbon nanotube forest as a medium for multiphoton thermal-photoemission.

    Science.gov (United States)

    Vahdani Moghaddam, Mehran; Yaghoobi, Parham; Sawatzky, George A; Nojeh, Alireza

    2015-04-28

    Combining the photoelectric and thermionic mechanisms to generate free electrons has been of great interest since the early days of quantum physics as exemplified by the Fowler-DuBridge theory, and recently proposed for highly efficient solar conversion. We present experimental evidence of this combined effect over the entire range spanning room-temperature photoemission to thermionic emission. Remarkably, the optical stimulus alone is responsible for both heating and photoemission at the same time. Moreover, the current depends on optical intensity quadratically, indicating two-photon photoemission, for intensities of ca. 1-50 W/cm(2), which are orders of magnitude below the intensities required for two-photon photoemission from bulk metals. This surprising behavior appears to be enabled by the internal nanostructure of the carbon nanotube forest, which captures photons effectively, yet allows electrons to escape easily.

  3. 用测井资料计算碳酸盐岩渗透率%Calculation of Carbonate Formation Permeability with Log Data

    Institute of Scientific and Technical Information of China (English)

    罗利

    2001-01-01

    Carbonate formation permeability depends on pore size, throat and fracture width, etc.. In view of pore and fracture abundance along with their functions in reservoir and percolation, carbonate reservoir may be divided into three types: porous, fractured-porous and fractured. The reservoir intervals can be picked up by core analysis and FMI data. Recognition samples from conventional log data indicate the 2-D distribution of the reservoir by non-linear mapping processing. The BP neural-network-based reservoir model provides the same result as that of FMI and core analysis. Fracture density is determined from the grey static model; Pore structures parameters are derived from calculating the throat sizes and pore bending deflection and correcting porosity for clay and organic matter. Math model of permeability is set up by non-parameter regression in accordance with the reservoir types, with which calculation accuracy of the permeability has been apparently improved.%罗利.用测井资料计算碳酸盐岩渗透率.测井技术,2001,25(2):139~141 碳酸盐岩渗透率大小取决于孔隙大小、喉道宽度和裂缝宽度等因素。根据孔隙和裂缝的发育情况及其在储集和渗滤中所起的作用,将碳酸盐岩储层划分为孔隙型、裂缝-孔隙型和裂缝型3种储集类型。从岩心分析、成像测井资料中划分出含3种储集类型的储层段。从常规测井资料中提取出指示孔隙和裂缝的参数形成识别样本,对样本做非线性映射处理,得到不同类型储层在X-Y空间上的分布。用BP网络建立识别储集类型模型,识别结果与成像测井识别结果和岩心分析结果吻合。用灰色静态模型计算裂缝密度,对孔隙度做泥质、有机质校正,计算喉道大小及弯曲程度,合成孔隙结构参数。用非参数回归方法按储层类型建立计算渗透率的数学模型。经实际资料处理,计算渗透

  4. Nanotube-based Sensors and Systems for Outer Planetary Exploration

    Science.gov (United States)

    Noca, F.; Hunt, B. D.; Hoenk, M. E.; Choi, D.; Kowalczyk, R.; Williams, R.; Xu, J.; Koumoutsakos, P.

    2001-01-01

    Direct sensing and processing at the nanometer scale offer NASA the opportunity to expand its capabilities in deep space exploration, particularly for the search for signatures of life, the analysis of planetary oceans and atmospheres, and communications systems. Carbon nanotubes, with their unique mechanical, electrical, and radiation-tolerant properties, are a promising tool for this exploration. We are developing devices based on carbon nanotubes, including sensors, actuators, and oscillators. Additional information is contained in the original extended abstract.

  5. Scanning and transmission electron microscopy investigation of multiwall carbon nanotube/nickel oxide nanocomposite thin films

    CSIR Research Space (South Africa)

    Roro, Kittessa T

    2011-12-01

    Full Text Available Owing to their unique electronic and optical properties, nanocomposite thin films are widely used for converting solar radiation therapy into other conventional energy forms, such as heat and electricity. Carbon nanotube-based composites which can...

  6. Magneto-Elastic Vibration of Multi-Walled Carbon Nanotubes based on a Rigorous Van Der Waals Interaction%基于严格范德华力作用的多壁碳纳米管磁弹性振动

    Institute of Scientific and Technical Information of China (English)

    张薇; 王熙

    2013-01-01

    给出了一种求解在任意两管之间严格范德华力相互作用下多壁碳纳米管磁弹性振动频率的解析方法.研究结果表明,在轴向磁场的作用下,严格范德华力相互作用对多壁碳纳米管最高磁弹性振动频率的影响大于对最低振动频率的影响;严格范德华力作用下多壁碳纳米管的最高磁弹性振动频率要高于经典范德华力作用下多壁碳纳米管的最高磁弹性振动频率;严格范德华力对磁弹性振动频率的影响依赖于碳纳米管层间距的变化和管的层数,且随着多壁碳纳米管层数的增加而趋于一个稳定值.本文的研究结果对于碳纳米管作为基本元件在纳米电子元件中的实际应用具有一定的参考价值.%This paper presents an analytical method to solve magneto-elastic vibrations of multiwall carbon nanotubes under a rigorous van der Waals interaction. Results show that under the axial magnetic field, the effects of the rigorous van der Waals force on the highest frequency of multi-walled carbon tubes are larger than the effects on its lowest frequency, and the highest frequency of multi-walled carbon tubes under rigorous van der Waals force is higher than that under classical van der Waals force. The influence of rigorous van der Waals force on magneto-elastic frequency depends on the change of interlayer spacing and the layer numbers of tubes and as the layer numbers increase the influence tends to a steady value. The investigation result is a valuable reference for the carbon nanotubes's practical application as basic electromagnetic elements.

  7. Crustal permeability: Introduction to the special issue

    Science.gov (United States)

    Ingebritsen, Steven E.; Gleeson, Tom

    2015-01-01

    The topic of crustal permeability is of broad interest in light of the controlling effect of permeability on diverse geologic processes and also timely in light of the practical challenges associated with emerging technologies such as hydraulic fracturing for oil and gas production (‘fracking’), enhanced geothermal systems, and geologic carbon sequestration. This special issue of Geofluids is also motivated by the historical dichotomy between the hydrogeologic concept of permeability as a static material property that exerts control on fluid flow and the perspective of economic geologists, geophysicists, and crustal petrologists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. Issues associated with fracking, enhanced geothermal systems, and geologic carbon sequestration have already begun to promote a constructive dialog between the static and dynamic views of permeability, and here we have made a conscious effort to include both viewpoints. This special issue also focuses on the quantification of permeability, encompassing both direct measurement of permeability in the uppermost crust and inferential permeability estimates, mainly for the deeper crust.

  8. Massive radius-dependent flow slippage in carbon nanotubes.

    Science.gov (United States)

    Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

    2016-09-08

    Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting, yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.

  9. Massive radius-dependent flow slippage in carbon nanotubes

    Science.gov (United States)

    Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

    2016-09-01

    Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting, yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.

  10. 用于染料敏化太阳能电池的多壁碳纳米管基对电极的制备与表征%Fabrication and characterization of a multi-walled carbon nanotube-based counter electrode for dye-sensitized solar cells

    Institute of Scientific and Technical Information of China (English)

    郑威; 齐涛; 张永超; 石海英; 田均庆

    2015-01-01

    A counter-electrode ( CE) for dye-sensitized solar cells ( DSSCs) was prepared by coating a slurry containing acid-oxi-dized multi-wall carbon nanotubes and nano-graphite powder onto a fluorine-doped tin oxide conducting glass substrate. The samples were characterized by SEM, TEM, EDS and IR spectroscopy. The CE performance in the DSSCs with MgO-doped TiO2 as the pho-toanode was investigated by measurements of current-voltage curves, cyclic voltammetry and electrochemical impedance spectrosco-py. Results show that the cell with the CE exhibits the best photoelectric properties of all the carbon-based CEs investigated. The short-circuit current density (Jsc) is 4. 67 mA/cm2, the open-circuit voltage (Voc) is 0. 53 V and photoelectric conversion efficiency is up to 4. 10%, which are comparable with those of the Pt-based CE in DSSCs.%经酸化处理的多壁碳纳米管( MWCNTs)与纳米石墨复合后沉积在FTO导电玻璃基底上制备出染料敏华太阳能电池薄膜对电极. 利用SEM﹑TEM﹑EDS与IR光谱对其进行表征. 以MgO掺杂的TiO2 薄膜为光阳极对电池通过循环伏安法( CV曲线)﹑电化学阻抗谱( EIS)和伏安特性曲线( J-V)进行光电性能分析. 结果表明:酸化处理的MWCNTs与纳米石墨复合对电极展现出优异的光催化性能,有利于电池光电性能的提高. 电池开路电压及短路电流密度分别可达 0. 53 V﹑4. 67 mA/cm2 ,其光电转换效率达到4. 10%,与铂对电极的性能相当.

  11. CARBON DIOXIDE SEPARATION BY SELECTIVE PERMEATION.

    Science.gov (United States)

    CARBON DIOXIDE , SEPARATION), (*PERMEABILITY, CARBON DIOXIDE ), POROUS MATERIALS, SILICON COMPOUNDS, RUBBER, SELECTION, ADSORPTION, TEMPERATURE, PRESSURE, POLYMERS, FILMS, PLASTICS, MEMBRANES, HUMIDITY.

  12. Carbon Nanotubes – Interactions with Biological Systems

    OpenAIRE

    Reis, Joana; Capela-Silva, Fernando; Potes, José; Fonseca, Alexandra; Oliveira, Mónica; Kanagaraj, Subramani; Marques, António Torres

    2011-01-01

    his book chapter discusses the prospective biomedical applications of carbon nanotubes based materials, the impact of carbon nanotubes properties in the interaction with biological systems. Protein adsorption, impact on cell viability and cytokine production are explored. Potential respiratory and dermal toxicity are reviewed, as the difficulties on studying the biological response. In face of recent studies, special attention is drawn upon promising orthopaedic use.

  13. Catalytic wet air oxidation of bisphenol A solution in a batch-recycle trickle-bed reactor over titanate nanotube-based catalysts.

    Science.gov (United States)

    Kaplan, Renata; Erjavec, Boštjan; Senila, Marin; Pintar, Albin

    2014-10-01

    Catalytic wet air oxidation (CWAO) is classified as an advanced oxidation process, which proved to be highly efficient for the removal of emerging organic pollutant bisphenol A (BPA) from water. In this study, BPA was successfully removed in a batch-recycle trickle-bed reactor over bare titanate nanotube-based catalysts at very short space time of 0.6 min gCAT g(-1). The as-prepared titanate nanotubes, which underwent heat treatment at 600 °C, showed high activity for the removal of aqueous BPA. Liquid-phase recycling (5- or 10-fold recycle) enabled complete BPA conversion already at 200 °C, together with high conversion of total organic carbon (TOC), i.e., 73 and 98 %, respectively. The catalyst was chemically stable in the given range of operating conditions for 189 h on stream.

  14. 多壁碳纳米管分散固相萃取-LC-MS/MS法分析烟草中114种农药残留%Simultaneous Determination of 114 Pesticide Residues in Tobacco by Multi-walled Carbon Nanotube-based Dispersive Solid Phase Extraction and LC-MS/MS

    Institute of Scientific and Technical Information of China (English)

    余斐; 陈黎; 艾丹; 潘立宁; 胡斌; 刘惠民

    2015-01-01

    建立了一种以多壁碳纳米管(MWCNTs)为吸附剂的分散固相萃取(DSPE)、液相色谱-串联质谱(LC-MS/MS)测定烟草中114种农药残留的分析方法。通过优化实验,选择并确定了MWCNTs的型号和用量,在QuEChERS方法的基础上改善了样品净化效果。结果表明:①以外径>50 nm、用量5 mg的MWCNTs为净化剂材料,可以获得比N-丙基乙二胺(PSA)更好的净化效果。②工作曲线线性良好(r2>0.999),3个添加水平(0.02,0.05,0.20 mg/kg)的平均回收率为69%~119%,相对标准偏差为1%~19%,方法定量限(LOQ)在0.2~40.0μg/kg之间。该方法准确度高、灵敏度好、操作简便,适合用于烟草样品中114种农药残留的检测。%A method combining dispersive solid phase extraction (DSPE), wherein multi-walled carbon nanotubes (MWCNTs) were used as adsorption material, with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for simultaneously determining 114 pesticide residues in tobacco. The type and adding rate of MWCNTs were optimized by experiments, and the purification of samples was improved by QuEChERS method. The results showed that: 1) It was more efficient using 5 mg MWCNTs of above 50 nm in external diameter than using N-Propylethane-1,2-diamine (PSA) in sample purification. 2) The calibration curve presented good linearity (r2>0.999). The average recoveries at spiked levels of 0.02, 0.05 and 0.20 mg/kg ranged from 69% to 119% with the relative standard deviations of 1%-19%, and the LOQs of the method were in the range of 0.2-40.0 g/kg. The developed method is accurate, sensitive, convenient, and suitable.

  15. 欢北低渗透油藏二氧化碳驱可行性研究%Feasibility Study on carbon dioxide flooding for HuanBei low permeability reservoir

    Institute of Scientific and Technical Information of China (English)

    周君

    2015-01-01

    欢北低渗透油藏在注水开发中存在油层纵向动用不均、水驱开发驱油效率低等问题.为解决以上问题,在该块开展了二氧化碳驱可行性研究,最后认为该油藏适合注二氧化碳驱开发.%There are some problems in the water injection development of HuanBei low permeability reservoir,such as unequal oil reservoir development,low oil displacement efficiency.In order to solve these problems,the feasibility of carbon dioxide flooding in this reservoir was studied and it was considered suitable for carbon dioxide flooding.

  16. STUDY ON THE PERMEABILITY OF CARBONATE ROCK GEOTHERMAL RESERVOIR IN BEIJING%北京地区碳酸盐岩热储渗透性研究

    Institute of Scientific and Technical Information of China (English)

    王树芳; 庞忠和; 何铁柱; 林沛; 刘凯; 刘久荣

    2014-01-01

    Beijing as capital of China is located in North China.The geothermal field in Beijing is mainly medium-low temperature conductive type,in which the Wumishan Formation with a thickness of more than 2000m of the Jixian System is the main reservoir and the rock of the Wumishan Formation is dolomite.Conductivity of the reservoir was usually calculated to understand reservoir characteristics, which could not accurately reflect permeability of the reservoir due to density variation of geothermal water.In order to understand permeability of the reservoir to direct geothermal resources development,porosity and permeability data of 34 dolomite rock cores collected from field outcrop and down-hole were compared and analyzed.The results indicated that permeability of outcrop and down-hole ranges are (10.0001 158 ~0.33333 )×10-3 μm2 and (0.0088 ~0.334 )×10-3 μm2 respectively,and the average value are 0.0622321×10-3μm2 and 0.385316×10-3μm2.The porosity ranges from 0.25%to 3.00%.The permeability of the rock cores are so low that geothermal energy could not be exacted without factures and fissures generated from tectonic movement and karstification.Therefore,permeability calculated from pump test could reflect total permeability of rock matrix,fractures and fissures.The calculated permeability of reservoir from 110 pump tests ranges from 13.74×10-3μm2 to 104474.00×10-3μm2,and the average is 4797.58× 10-3μm2.The cumulated percentage of permeability values between 100×10-3μm2 and 1000×10-3μm2 are more than 75%,the values less than 100×10-3μm2 are only 13.64%,and the permeability values greater than 100000× 10-3μm2 are 0.91 percent.In order to demonstrate relationship between reservoir buried depth and permeability, the buried depth were divided into 500m,500~1000m,1000~1500m,1500~2000m,2000~2500m,2500~3000m and 3000~3500m.The average permeability and average buried depth were plotted together in x,y coordi-nates.The results indicated that the average

  17. Estimation of soil permeability

    Directory of Open Access Journals (Sweden)

    Amr F. Elhakim

    2016-09-01

    Full Text Available Soils are permeable materials because of the existence of interconnected voids that allow the flow of fluids when a difference in energy head exists. A good knowledge of soil permeability is needed for estimating the quantity of seepage under dams and dewatering to facilitate underground construction. Soil permeability, also termed hydraulic conductivity, is measured using several methods that include constant and falling head laboratory tests on intact or reconstituted specimens. Alternatively, permeability may be measured in the field using insitu borehole permeability testing (e.g. [2], and field pumping tests. A less attractive method is to empirically deduce the coefficient of permeability from the results of simple laboratory tests such as the grain size distribution. Otherwise, soil permeability has been assessed from the cone/piezocone penetration tests (e.g. [13,14]. In this paper, the coefficient of permeability was measured using field falling head at different depths. Furthermore, the field coefficient of permeability was measured using pumping tests at the same site. The measured permeability values are compared to the values empirically deduced from the cone penetration test for the same location. Likewise, the coefficients of permeability are empirically obtained using correlations based on the index soil properties of the tested sand for comparison with the measured values.

  18. Multiple—tube Permeable Element for Combined Blowing Converter

    Institute of Scientific and Technical Information of China (English)

    YANGWen-yuan; XUWei-hua; 等

    1994-01-01

    The method consisting of cold test and hot simulating has been proved to be reliable for designing permeable ele-ments.The carbon-magnesia multiple-tube permeable ele-ments which are formed by isostatical pressure have higher density,high heat resistance and good thermoshock resis-tance,The brickwork ,maintenance and erosion meha-nism of permeable elements were studied.The tehnology of combined blowing wa established based on the peculiari-ties of semi-steel refining at Panzhihua Irom& Steel Co.(PZISC).The service life of permeable elements reahed 600 heats,that means the permeable elements can work synchronitially with converter lining.

  19. Functionalized multi-walled carbon nanotube based sensors for distributed methane leak detection

    Science.gov (United States)

    This paper presents a highly sensitive, energy efficient and low-cost distributed methane (CH4) sensor system (DMSS) for continuous monitoring, detection and localization of CH4 leaks in natural gas infrastructure such as transmission and distribution pipelines, wells, and produc...

  20. Carbon Nanotube Based Electric Propulsion Thruster with Low Power Consumption Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Field emission electric propulsion (FEEP) thrusters have gained considerable attention for spacecrafts disturbance compensation because of excellent characteristics....

  1. Magnesium oxide grafted carbon nanotubes based impedimetric genosensor for biomedical application.

    Science.gov (United States)

    Patel, Manoj Kumar; Ali, Md Azahar; Srivastava, Saurabh; Agrawal, Ved Varun; Ansari, S G; Malhotra, Bansi D

    2013-12-15

    Nanostructured magnesium oxide (sizeoxide (ITO) coated glass electrode and have been utilized for Vibrio cholerae detection. Aminated 23 bases single stranded DNA (NH2-ssDNA) probe sequence (O1 gene) of V. cholerae has been covalently functionalized onto nMgO-cMWCNTs/ITO electrode surface using EDC-NHS chemistry. This DNA functionalized MgO grafted cMWCNTs electrode has been characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical techniques. The results of XPS studies reveal that sufficient O-C=O groups present at the nMgO-cMWCNTs surface are utilized for DNA binding. The results of hybridization studies conducted with fragmented target DNA (ftDNA) of V. cholerae using electrochemical impedance spectroscopy (EIS) reveal sensitivity as 3.87 Ω ng(-1) cm(-2), detection limit of ~21.70 ng µL(-1) in the linear range of 100-500 ng µL(-1) and stability of about 120 days. The proposed DNA functionalized nMgO-cMWCNTs nanomatrix provides a novel impedimetric platform for the fabrication of a compact genosensor device for biomedical application.

  2. Highly conductive and transparent carbon nanotube-based electrodes for ultrathin and stretchable organic solar cells

    Science.gov (United States)

    Fan, Qingxia; Zhang, Qiang; Zhou, Wenbin; Yang, Feng; Zhang, Nan; Xiao, Shiqi; Gu, Xiaogang; Xiao, Zhuojian; Chen, Huiliang; Wang, Yanchun; Liu, Huaping; Zhou, Weiya

    2017-02-01

    Not Available Project supported by the National Basic Research Program of China (Grant No. 2012CB932302), the National Natural Science Foundation of China (Grant Nos. 11634014, 51172271, 51372269, and 51472264), and the “Strategic Priority Research Program” of the Chinese Academy of Sciences (Grant No. XDA09040202).

  3. 吸波Cf和SiCf的制备及其微波电磁特性%Preparation of Radar Absorbing Carbon Fiber and Silicon Carbide Fiber and Their Microwave Permittivity and Permeability

    Institute of Scientific and Technical Information of China (English)

    赵东林; 沈曾民

    2001-01-01

    探讨了吸波Cf和吸波SiCf的制备方法和微波电磁特性,降低Cf的碳化温度、改变Cf的截面形状和大小、对Cf进行表面改性以及对Cf进行掺杂改性能制备出吸波性能优良的Cf。采用高温处理、对纤维进行表面改性和掺杂异种元素可制备出吸波SiCf。%Carbon fiber and silicon carbide fiber have been widely used in stealth technology,which are two main kinds of fibers to reinforce radar absorbing materials.Preparatibn methods and microwave permittivity and permeability of radar absorbing carbon fiber and silicon carbide fiber are discussed.Carbon fiber with good radar absorbing can be prepiared by decreasing its heat treatment temperature,changing its cross section shape and size,modifying outer surface and doping other elements into the carbon fiber.Silicon carbide fiber with radar absorbing can be prepared by increasing the heat treatment temperature,modifying fiber surface and doping other elements into fiber.

  4. Frictional stability-permeability relationships for fractures in shales: Friction-Permeability Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yi [Department of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park Pennsylvania USA; Elsworth, Derek [Department of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park Pennsylvania USA; Department of Geosciences, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park Pennsylvania USA; Wang, Chaoyi [Department of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park Pennsylvania USA; Ishibashi, Takuya [Department of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, Pennsylvania State University, University Park Pennsylvania USA; Fukushima Renewable Energy Institute, National Institute of Advanced Industrial Science and Technology, Koriyama Japan; Fitts, Jeffrey P. [Department of Civil and Environmental Engineering, Princeton University, Princeton New Jersey USA

    2017-01-01

    There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction-stability-permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate-rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate-rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction-stability-permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.

  5. Gas and Water Permeability of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

    2012-11-01

    The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

  6. Permeability prediction in chalks

    DEFF Research Database (Denmark)

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

    2011-01-01

    The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability....... The relationships between permeability and porosity from core data were first examined using Kozeny’s equation. The data were analyzed for any correlations to the specific surface of the grain, Sg, and to the hydraulic property defined as the flow zone indicator (FZI). These two methods use two different approaches...... to enhance permeability prediction fromKozeny’s equation. The FZI is based on a concept of a tortuous flow path in a granular bed. The Sg concept considers the pore space that is exposed to fluid flow and models permeability resulting from effective flow parallel to pressure drop. The porosity-permeability...

  7. Halloysite nanotube-based electrospun ceramic nanofibre mat: a novel support for zeolite membranes

    Science.gov (United States)

    Chen, Zhuwen; Zeng, Jiaying; Lv, Dong; Gao, Jinqiang; Zhang, Jian; Bai, Shan; Li, Ruili; Hong, Mei; Wu, Jingshen

    2016-12-01

    Some key parameters of supports such as porosity, pore shape and size are of great importance for fabrication and performance of zeolite membranes. In this study, we fabricated millimetre-thick, self-standing electrospun ceramic nanofibre mats and employed them as a novel support for zeolite membranes. The nanofibre mats were prepared by electrospinning a halloysite nanotubes/polyvinyl pyrrolidone composite followed by a programmed sintering process. The interwoven nanofibre mats possess up to 80% porosity, narrow pore size distribution, low pore tortuosity and highly interconnected pore structure. Compared with the commercial α-Al2O3 supports prepared by powder compaction and sintering, the halloysite nanotube-based mats (HNMs) show higher flux, better adsorption of zeolite seeds, adhesion of zeolite membranes and lower Al leaching. Four types of zeolite membranes supported on HNMs have been successfully synthesized with either in situ crystallization or a secondary growth method, demonstrating good universality of HNMs for supporting zeolite membranes.

  8. Halloysite nanotube-based electrospun ceramic nanofibre mat: a novel support for zeolite membranes

    Science.gov (United States)

    Chen, Zhuwen; Zeng, Jiaying; Lv, Dong; Gao, Jinqiang; Zhang, Jian; Bai, Shan; Li, Ruili; Wu, Jingshen

    2016-01-01

    Some key parameters of supports such as porosity, pore shape and size are of great importance for fabrication and performance of zeolite membranes. In this study, we fabricated millimetre-thick, self-standing electrospun ceramic nanofibre mats and employed them as a novel support for zeolite membranes. The nanofibre mats were prepared by electrospinning a halloysite nanotubes/polyvinyl pyrrolidone composite followed by a programmed sintering process. The interwoven nanofibre mats possess up to 80% porosity, narrow pore size distribution, low pore tortuosity and highly interconnected pore structure. Compared with the commercial α-Al2O3 supports prepared by powder compaction and sintering, the halloysite nanotube-based mats (HNMs) show higher flux, better adsorption of zeolite seeds, adhesion of zeolite membranes and lower Al leaching. Four types of zeolite membranes supported on HNMs have been successfully synthesized with either in situ crystallization or a secondary growth method, demonstrating good universality of HNMs for supporting zeolite membranes. PMID:28083098

  9. Permeability of edible coatings.

    Science.gov (United States)

    Mishra, B; Khatkar, B S; Garg, M K; Wilson, L A

    2010-01-01

    The permeabilities of water vapour, O2 and CO2 were determined for 18 coating formulations. Water vapour transmission rate ranged from 98.8 g/m(2).day (6% beeswax) to 758.0 g/m(2).day (1.5% carboxymethyl cellulose with glycerol). O2 permeability at 14 ± 1°C and 55 ± 5% RH ranged from 1.50 to 7.95 cm(3)cm cm(-2)s(-1)Pa(-1), with CO2 permeability 2 to 6 times as high. Permeability to noncondensable gases (O2 and CO2) was higher for hydrophobic (peanut oil followed by beeswax) coatings as compared to hydrophilic (whey protein concentrate and carboxymethyl cellulose).

  10. Permeability of edible coatings

    OpenAIRE

    B Mishra; Khatkar, B. S.; Garg, M. K.; Wilson, L.A.

    2010-01-01

    The permeabilities of water vapour, O2 and CO2 were determined for 18 coating formulations. Water vapour transmission rate ranged from 98.8 g/m2.day (6% beeswax) to 758.0 g/m2.day (1.5% carboxymethyl cellulose with glycerol). O2 permeability at 14 ± 1°C and 55 ± 5% RH ranged from 1.50 to 7.95 cm3cm cm−2s−1Pa−1, with CO2 permeability 2 to 6 times as high. Permeability to noncondensable gases (O2 and CO2) was higher for hydrophobic (peanut oil followed by beeswax) coatings as compared to hydrop...

  11. Soils - Mean Permeability

    Data.gov (United States)

    Kansas Data Access and Support Center — This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The...

  12. Permeable pavement study (Edison)

    Data.gov (United States)

    U.S. Environmental Protection Agency — While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types...

  13. Measurement and evaluation of the relationships between capillary pressure, relative permeability, and saturation for surrogate fluids for laboratory study of geological carbon sequestration

    Science.gov (United States)

    Mori, H.; Trevisan, L.; Sakaki, T.; Cihan, A.; Smits, K. M.; Illangasekare, T. H.

    2013-12-01

    Multiphase flow models can be used to improve our understanding of the complex behavior of supercritical CO2 (scCO2) in deep saline aquifers to make predictions for the stable storage strategies. These models rely on constitutive relationships such as capillary pressure (Pc) - saturation (Sw) and relative permeability (kr) - saturation (Sw) as input parameters. However, for practical application of these models, such relationships for scCO2 and brine system are not readily available for geological formations. This is due to the complicated and expensive traditional methods often used to obtain these relationships in the laboratory through high pressure and/or high-temperature controls. A method that has the potential to overcome the difficulty in conducting such experiments is to replicate scCO2 and brine with surrogate fluids that capture the density and viscosity effects to obtain the constitutive relationships under ambient conditions. This study presents an investigation conducted to evaluate this method. An assessment of the method allows us to evaluate the prediction accuracy of multiphase models using the constitutive relationships developed from this approach. With this as a goal, the study reports multiple laboratory column experiments conducted to measure these relationships. The obtained relationships were then used in the multiphase flow simulator TOUGH2 T2VOC to explore capillary trapping mechanisms of scCO2. A comparison of the model simulation to experimental observation was used to assess the accuracy of the measured constitutive relationships. Experimental data confirmed, as expected, that the scaling method cannot be used to obtain the residual and irreducible saturations. The results also showed that the van Genuchten - Mualem model was not able to match the independently measured kr data obtained from column experiments. Simulated results of fluid saturations were compared with saturation measurements obtained using x-ray attenuations. This

  14. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  15. Effects of Biochar on Air and Water Permeability and Colloid and Phosphorus Leaching in Soils from a Natural Calcium Carbonate Gradient

    DEFF Research Database (Denmark)

    Kahawaththa Gamage, Inoka Damayanthi Kumari; Møldrup, Per; Paradelo Pérez, Marcos;

    2014-01-01

    in an agricultural field in Denmark with a calcium carbonate (CaCO3) gradient. The field comprised four reference plots and four plots to which biochar (birch wood pyrolyzed at 500°C) was applied at a rate of 20 t ha−1. Five undisturbed soil columns (10 cm diam., 8 cm height) were sampled from each plot 7 mo after...... biochar application, and a series of leaching experiments was conducted. The leachate was analyzed for tritium (used as a tracer), colloids, and phosphorus concentration. The results revealed that the presence of CaCO3 has resulted in marked changes in soil structure (bulk density) and soil chemical...... to be time dependent in soils with low CaCO3. Biochar-amended soils showed higher colloid and P release than reference soils. Field-scale variations in total colloid and P leaching reflected clear effects of changes in pH and ionic strength due to the presence of CaCO3. There was a linear relationship...

  16. Measurement of relative permeability of fuel cell diffusion media

    KAUST Repository

    Hussaini, I.S.

    2010-06-01

    Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented and new correlations for in-plane relative permeability of water and air are established. © 2010 Elsevier B.V. All rights reserved.

  17. Carbon nanotubes from synthesis to in vivo biomedical applications.

    Science.gov (United States)

    Sajid, Muhammad Imran; Jamshaid, Usama; Jamshaid, Talha; Zafar, Nadiah; Fessi, H; Elaissari, Abdelhamid

    2016-03-30

    Owing to their unique and interesting properties, extensive research round the globe has been carried out on carbon nanotubes and carbon nanotubes based systems to investigate their practical usefulness in biomedical applications. The results from these studies demonstrate a great promise in their use in targeted drug delivery systems, diagnostic techniques and in bio-analytical applications. Although, carbon nanotubes possess quite interesting properties, which make them potential candidates in the biomedical science, but they also have some inherent properties which arise great concern regarding their biosafety. In this comprehensive review, we have discussed different aspects of carbon nanotubes and carbon nanotube based systems related to biomedical applications. In the beginning, a short historical account of these tiny yet powerful particles is given followed by discussion regarding their types, properties, methods of synthesis, large scale production method, purification techniques and characterization aspects of carbon nanotubes. In the second part of the review, the functionalization of carbon nanotubes is reviewed in detail, which is not only important to make them biocompatible and stable in biological systems but also render them a great property of loading various biomolecules, diagnostic and therapeutic moieties resulting in diversified applications. In the final part of the review, emphasis is given on the pharmacokinetic aspects of carbon nanotubes including administration routes, absorption mechanisms, distribution and elimination of carbon nanotubes based systems. Lastly, a comprehensive account about the potential biomedical applications has been given followed by insights into the future.

  18. A Thermal Model for Carbon Nanotube Interconnects

    Science.gov (United States)

    Mohsin, Kaji Muhammad; Srivastava, Ashok; Sharma, Ashwani K.; Mayberry, Clay

    2013-01-01

    In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI) interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT) interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  19. Relative permeability through fractures

    Energy Technology Data Exchange (ETDEWEB)

    Diomampo, Gracel, P.

    2001-08-01

    The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.

  20. Permeability measuremens of brazilian Eucalyptus

    Directory of Open Access Journals (Sweden)

    Marcio Rogério da Silva

    2010-09-01

    Full Text Available The permeability of Brazilian Eucalyptus grandis and Eucalyptus citriodora wood was measured in a custom build gas analysis chamber in order to determine which species could be successfully treated with preservatives. Liquid permeability was tested using an emulsion of Neen oil and a control of distillated water. Air was used to test the gas phase permeability. For both Eucalyptus grandis and Eucalyptus citriodora, the longitudinal permeability of gas was shown to be about twice as great as the liquid phase permeability. No radial permeability was observed for either wood. The permeability of air and water through the sapwood of Eucalyptus grandis was greater than that through the sapwood of Eucalyptus citriodora. The permeability of neen oil preservative through the sapwood of Eucalyptus grandis was also greater than through the sapwood of E. Citradora, but the difference was not statistically significant. Scanning Electron Microscopy images showed that the distribution and obstruction in the vessels could be correlated with observed permeability properties. Irrespective of the causes of differences in permeability between the species, the fluid phase flux through the sapwood of both species was significant, indicating that both Eucalyptus grandis and Eucalyptus citriodora could be successfully treated with wood preservative.

  1. Low Permeability Polyimide Insulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  2. Diagenetic effect on permeabilities of geothermal sandstone reservoirs

    DEFF Research Database (Denmark)

    Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

    The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

  3. Anisotropic Variation Law of Rock Permeability with the Burial Depth of Limestone

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Permeability tensors of both macrofracture and microfracture systems were measured progressively along the depth of limestone formations at severed sites. It was found that the principal permeability values Kx, Ky and Kz in these permeability tensors all decrease simultaneously and logarithmically with depth. However, the limestone aquifers are composed of an upper region where the larger permeability ellipsoid is upright or prolate and characterized by Kz>Kx and Kz>Ky, a transitional zone, and a lower zone whose smaller permeability ellipsoid is horizontal or oblate and characterized by Kz<Kx and Kz<Ky. The inversion of the permeability ellipsoids in direction indicates that the anisotropy of rock permeability with the depth of limestone formations has evidently changed. The anisotropic variation law of permeability tensors in a macrofracture system displays a similar pattern with that in a microfracture system. It is next to impossible to examine the rock permeability tensor of the aquifer just by measuring the hydraulic parameters of macrofracture system directly, unless the limestone aquifer is exposed on or near the earth's surface. Therefore, the permeability tensors of a macrofracture system at any depth may be indirectly and roughly determined from the gaugeable permeability tensors of the microfracture system by conversion. This anisotropic variation law of rock permeability with depth is of great significance in the study of three-dimensional fracture water flow the huge carbonate formations and in the research on the conditions of karst development and karst distribution.

  4. Computational Nanotechnology of Molecular Materials, Electronics, and Actuators with Carbon Nanotubes and Fullerenes

    Science.gov (United States)

    Srivastava, Deepak; Menon, Madhu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2001-01-01

    The role of computational nanotechnology in developing next generation of multifunctional materials, molecular scale electronic and computing devices, sensors, actuators, and machines is described through a brief review of enabling computational techniques and few recent examples derived from computer simulations of carbon nanotube based molecular nanotechnology.

  5. Study of Carbon Nanotube-Substrate Interaction

    Directory of Open Access Journals (Sweden)

    Jaqueline S. Soares

    2012-01-01

    Full Text Available Environmental effects are very important in nanoscience and nanotechnology. This work reviews the importance of the substrate in single-wall carbon nanotube properties. Contact with a substrate can modify the nanotube properties, and such interactions have been broadly studied as either a negative aspect or a solution for developing carbon nanotube-based nanotechnologies. This paper discusses both theoretical and experimental studies where the interaction between the carbon nanotubes and the substrate affects the structural, electronic, and vibrational properties of the tubes.

  6. Nanosensors for the smart city : new insight on promising carbon nanotubes devices

    OpenAIRE

    Lebental, Bérengère

    2011-01-01

    The development of nanosensors for the smart-city is discussed in the framework of the Sense-City Equipex project. Two types of carbon nanotubes based sensors are discussed, a field effect transistor using a carbon nanotubes randow network as channel for humidity sensing and a microsonar using an aligned array of carbon nanotubes as vibrating membrane for microporosity monitoring in concrete. The Sense-city project is also described.

  7. Permeability of intertidal sandflats: Impact of temporal variability on sediment metabolism

    Science.gov (United States)

    Zetsche, E.; Bulling, M. T.; Witte, U.

    2012-07-01

    The effects of sediment permeability on sediment oxygen consumption (SOC) in an intertidal permeable sandflat were studied over a 1-year period. Our study demonstrates that temporal variation in sediment metabolism was not only driven by temperature, but also changes in sediment permeability and total carbon content over time. High SOC rates in the summer months (seasonal mean 36.5 mmol m-2 d-1) could be attributed to high temperatures affecting metabolic processes, the rapid turnover of labile organic material and the presence of large amounts of microphytobenthos and their exudates in interstitial pore spaces. The resultant clogging of pores lowered sediment permeabilities and led to the observation of increasing SOC rates at decreasing permeabilities. Despite higher permeabilities, oxygen consumption rates in winter (seasonal mean 17.3 mmol m-2 d-1) were less than half those measured in the summer, reflecting the presence of more persistent refractory material and lower temperatures. During the winter, a major storm event reworked the sediment and significantly changed the permeability, affecting SOC rates. As sediment permeability rose by ˜25%, SOC rates were increased by ˜35% in the month after the event compared to the previous month. Our results show that temporal variation, not only in temperature and carbon content, but also in sediment permeability, affects sediment metabolism and that resuspension and storm events are necessary to unclog systems and maintain high remineralisation rates in organically poor permeable sands.

  8. Carbon-Nanotube-Based Epoxy Matrix Thermal Interface Materials for Thermal Management in Load Bearing Aerospace Structures

    Science.gov (United States)

    2012-01-12

    electron scattering at the grain boundaries as well as the twin boundaries in addition to the scattering from the boundary surface at lower temperatures...measurements are obtained by ellipsometry and profilometer. The estimation of the mean grain size in both films and the evidence of twin boundaries are...5c,d) also reveal the presence of twin boundaries in both Sn films more often than grain boundaries. Moreover, the density of twin boundaries in

  9. Design of Carbon Nanotube-Based Gas-Diffusion Cathode for O2 Reduction by Multicopper Oxidases (Postprint)

    Science.gov (United States)

    2011-10-04

    Comm. 2004 , 6 , 526 . [ 35 ] S. Calabrese Barton , Electrochim. Acta 2005 , 50 , 2145 . [ 36 ] A. M. Kuznetsov , V. A...E. Piles , D. Lehnert , S. Calabrese Barton , R. Rincon , P. Atanassov , Electroanal. 2008 , 20 , 1099 . 7bH & Co. KGaA, Weinheim wileyonlinelibrary.com

  10. Permeability and compressibility of CNT/CNF grafted reinforcements

    NARCIS (Netherlands)

    Lomov, Stepan V.; Beyers, Lesley; Gorbatikh, Larissa; Verpoest, Ignaas; Koissin, Vitaly; Kotanjac, Zeljko; Karahan, Mehmet

    2010-01-01

    The paper studies compressibility and permeability of a CNT/CNF-grafted woven carbon reinforcement. It is shown that the pressure needed to achieve the target fibre volume fraction of the perform increases drastically when CNT/CNF are present in the preform. This can lower the achievable fibre volum

  11. Modelling the permeability of polymers: a neural network approach

    NARCIS (Netherlands)

    Wessling, M.; Mulder, M.H.V.; Bos, A.; Linden, van der M.K.T.; Bos, M.; Linden, van der W.E.

    1994-01-01

    In this short communication, the prediction of the permeability of carbon dioxide through different polymers using a neural network is studied. A neural network is a numeric-mathematical construction that can model complex non-linear relationships. Here it is used to correlate the IR spectrum of a p

  12. Permeability and compressibility of CNT/CNF grafted reinforcements

    NARCIS (Netherlands)

    Lomov, Stepan V.; Beyers, Lesley; Gorbatikh, Larissa; Verpoest, Ignaas; Koysin, V.; Kotanjac, Zeljko; Karahan, Mehmet

    2010-01-01

    The paper studies compressibility and permeability of a CNT/CNF-grafted woven carbon reinforcement. It is shown that the pressure needed to achieve the target fibre volume fraction of the perform increases drastically when CNT/CNF are present in the preform. This can lower the achievable fibre volum

  13. Permeability and compressibility of CNT/CNF grafted reinforcements

    NARCIS (Netherlands)

    Lomov, Stepan V.; Beyers, Lesley; Gorbatikh, Larissa; Verpoest, Ignaas; Koysin, V.; Kotanjac, Zeljko; Karahan, Mehmet

    2010-01-01

    The paper studies compressibility and permeability of a CNT/CNF-grafted woven carbon reinforcement. It is shown that the pressure needed to achieve the target fibre volume fraction of the perform increases drastically when CNT/CNF are present in the preform. This can lower the achievable fibre

  14. Permeability and Selectivity of Sulfur Dioxide and Carbon Dioxide in Supported Ionic Liquid Membranes%二氧化硫和二氧化碳在离子液体支撑液膜中的渗透率和选择性

    Institute of Scientific and Technical Information of China (English)

    江滢滢; 吴有庭; 王文婷; 李磊; 周政; 张志炳

    2009-01-01

    Permeabilities and selectivities of gases such as carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen (N2) and methane (CH4) in six imidazolium-based ionic liquids ([emim][BF4], [bmim][BF4], [bmim][PF6], [hmim][BF4], [bmim][Tf2N] and [emim][CF3SO3]) supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45℃ and pressure of N2 from 100 to 400 kPa. It is found that SO2 has the highest permeability in the tested supported ionic liquid membranes, being an order of magnitude higher than that of CO2, and about 2 to 3 or-ders of magnitude larger than those of N2 and CH4. The observed selectivity of SO2 over the two ordinary gas components is also striking. It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes, as well as the nature of ionic liquids play important roles in the gas permeation. A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases. By considering the factors that influence the permeabilities and selectivities of CO2 and SO2, it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.

  15. ANALYSIS OF MATERIAL MECHANICAL PROPERTIES FOR SINGLE-WALLED CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    Fu Yiming; Xu Xiaoxian

    2005-01-01

    Abstract The carbon-carbon bond between two nearest-neighboring atoms is modeled as a beam and the single-walled carbon nanotubes are treated as the space frame structures in order to analyze the mechanical properties of carbon nanotubes. Based on the theory of TersoffBrenner force field, the energy relationships between the carbon-carbon bond and the beam model are obtained, and the stiffness parameters of the beam are determined. By applying the present model, the Young's moduli of the single-walled carbon nanotubes with different tube diameters are determined. And the present results are compared with available data.

  16. Permeability testing of biomaterial membranes

    Energy Technology Data Exchange (ETDEWEB)

    Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

    2008-09-01

    The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

  17. Defect-related hysteresis in nanotube-based nano-electromechanical systems

    Directory of Open Access Journals (Sweden)

    Pantelides Sokrates

    2011-01-01

    Full Text Available Abstract The electronic properties of multi-walled carbon nanotubes (MWCNTs depend on the positions of their walls with respect to neighboring shells. This fact can enable several applications of MWCNTs as nano-electromechanical systems (NEMS. In this article, we report the findings of a first-principles study on the stability and dynamics of point defects in double-walled carbon nanotubes (DWCNTs and their role in the response of the host systems under inter-tube displacement. Key defect-related effects, namely, sudden energy changes and hysteresis, are identified, and their relevance to a host of MWCNT-based NEMS is highlighted. The results also demonstrate the dependence of these effects on defect clustering and chirality of DWCNT shells.

  18. Single-walled carbon nanotubes as near-infrared optical biosensors for life sciences and biomedicine.

    Science.gov (United States)

    Jain, Astha; Homayoun, Aida; Bannister, Christopher W; Yum, Kyungsuk

    2015-03-01

    Single-walled carbon nanotubes that emit photostable near-infrared fluorescence have emerged as near-infrared optical biosensors for life sciences and biomedicine. Since the discovery of their near-infrared fluorescence, researchers have engineered single-walled carbon nanotubes to function as an optical biosensor that selectively modulates its fluorescence upon binding of target molecules. Here we review the recent advances in the single-walled carbon nanotube-based optical sensing technology for life sciences and biomedicine. We discuss the structure and optical properties of single-walled carbon nanotubes, the mechanisms for molecular recognition and signal transduction in single-walled carbon nanotube complexes, and the recent development of various single-walled carbon nanotube-based optical biosensors. We also discuss the opportunities and challenges to translate this emerging technology into biomedical research and clinical use, including the biological safety of single-walled carbon nanotubes. The advances in single-walled carbon nanotube-based near-infrared optical sensing technology open up a new avenue for in vitro and in vivo biosensing with high sensitivity and high spatial resolution, beneficial for many areas of life sciences and biomedicine.

  19. Methods to Measure Water Permeability.

    Science.gov (United States)

    Solenov, Evgeniy I; Baturina, Galina S; Katkova, Liubov E; Zarogiannis, Sotirios G

    2017-01-01

    Water permeability is a key feature of the cell plasma membranes and it has seminal importance for a number of cell functions such as cell volume regulation, cell proliferation, cell migration, and angiogenesis to name a few. The transport of water occurs mainly through plasma membrane water channels , the aquaporins, who have very important function in physiological and pathophysiological states. Due to the above the experimental assessment of the water permeability of cells and tissues is necessary. The development of new methodologies of measuring water permeability is a vibrant scientific field that constantly develops during the past three decades along with the advances in imaging mainly. In this chapter we describe and critically assess several methods that have been developed for the measurement of water permeability both in living cells as well as in tissues with a focus in the first category.

  20. Geothermal Permeability Enhancement - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  1. Calibrating NMR measured porosity/permeability relationships using µXRCT measurements

    Science.gov (United States)

    Mason, H. E.; Smith, M. M.; Hao, Y.; Carroll, S.

    2015-12-01

    Carbonate reservoirs have garnered interest for potential use in carbon capture and storage (CCS) activities. To be suitable for long term carbon dioxide (CO2) storage, they must possess sufficient permeability either through existing connected pore space, or due to reactivity with CO2-acidified fluids. Adequate assessment of the target formation permeability will rely on accurate downhole well-logging tools. Primary among these tools is nuclear magnetic resonance (NMR) well-logging. Application of this tool relies on our ability to relate the porosity and pore distributions measured by NMR to permeability. These methods are challenging to apply in carbonate reservoirs with complex mineralogies where pores sizes often span orders of magnitudes. We have assessed the ability of NMR methods to measure permeability using rocks from the Weyburn-Midale CO2 Monitoring and Storage Project Saskatchewan, Canada and the Arbuckle injection zone at the Wellington CO2 storage demonstration site, Kansas. Results of laboratory measured permeability values of these rocks indicate that the standard NMR methods for predicting permeability values can produce values off by orders of magnitude within the same flow units. In this presentation, we present the results of a combined NMR and micro X-ray computed tomography (μXRCT) study of these rock cores to better estimate downhole permeability values of carbonate rocks. The results of the study suggest that the dramatic differences in predicted permeability values derive from large differences in the matrix porosity, pore network tortuosities, and mineralogy of the various rock units. We will present new laboratory measurements, and methodologies aimed at producing a universal NMR calibration procedure for determining permeability in carbonate reservoirs. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  2. Dynamic up-scaling of relative permeability in chalk

    Energy Technology Data Exchange (ETDEWEB)

    Frykman, P.; Lindgaard, H.F.

    1997-12-31

    This paper describes how fine-scale geo-statistic reservoir models can be utilised for the up-scaling of two-phase flow properties, including both relative permeability and capillary pressure function. The procedure is applied to a North Sea chalk carbonate reservoir example, which is a high-porosity/low-permeability reservoir type. The study focuses on waterflooding as the main recovery scheme and for the given flow regime in the reservoir. The main purpose of the paper is to demonstrate the use of dynamic multi-step up-scaling methods in the preparation of detailed geological information for full field reservoir simulation studies. (au) EFP-96. 39 refs.

  3. A glass-sealed field emission x-ray tube based on carbon nanotube emitter for medical imaging

    Science.gov (United States)

    Yeo, Seung Jun; Jeong, Jaeik; Ahn, Jeung Sun; Park, Hunkuk; Kwak, Junghwan; Noh, Eunkyong; Paik, Sanghyun; Kim, Seung Hoon; Ryu, Jehwang

    2016-04-01

    We report the design and fabrication of a carbon nanotube based a glass-sealed field emission x-ray tube without vacuum pump. The x-ray tube consists of four electrodes with anode, focuser, gate, and cathode electrode. The shape of cathode is rectangular for isotropic focal spot size at anode target. The obtained x-ray images show clearly micrometer scale.

  4. Experimental investigation the effect of nanoparticles on the oil-water relative permeability

    Science.gov (United States)

    Amedi, Hamidreza; Ahmadi, Mohammad-Ali

    2016-05-01

    This paper presents the effects of the nanosilica particles on the water and oil relative permeability curves at reservoir conditions. Real reservoir crude oil sample was employed as an oil phase in relative permeability measurements. In addition, real carbonate reservoir rock samples were employed as a porous media in core displacement experiments. To determine relative permeability curves, the unsteady-state approach was employed in which Toth et al. method was applied to the recovery data points. By increasing the nanosilica content of the aqueous phase the oil relative permeability increased while the residual oil saturation decreased; however, by increasing the nanosilica concentration in the aqueous solution the water relative permeability decreased. The outcomes of this paper can provide a better understanding regarding chemically enhanced oil recovery (EOR) by nanoparticles. Moreover, relative permeability curves help us in the history matching section of reservoir simulation for any further EOR scenarios.

  5. Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

    Science.gov (United States)

    Yang, Hui Ying; Han, Zhao Jun; Yu, Siu Fung; Pey, Kin Leong; Ostrikov, Kostya; Karnik, Rohit

    2013-01-01

    Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

  6. Electronic transport properties of metallic single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    曹觉先; 颜晓红; 肖杨; 丁建文

    2003-01-01

    We have calculated the differential conductance of metallic carbon nanotubes by the scatter matrix method. It is found that the differential conductance of metallic nanotube-based devices oscillates as a function of the bias voltage between the two leads and the gate voltage. Oscillation period T is directly proportional to the reciprocal of nanotube length. In addition, we found that electronic transport properties are sensitive to variation of the length of the nanotube.

  7. Bentonite Permeability at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Katherine A. Daniels

    2017-01-01

    Full Text Available Repository designs frequently favour geological disposal of radioactive waste with a backfill material occupying void space around the waste. The backfill material must tolerate the high temperatures produced by decaying radioactive waste to prevent its failure or degradation, leading to increased hydraulic conductivity and reduced sealing performance. The results of four experiments investigating the effect of temperature on the permeability of a bentonite backfill are presented. Bentonite is a clay commonly proposed as the backfill in repository designs because of its high swelling capacity and very low permeability. The experiments were conducted in two sets of purpose-built, temperature controlled apparatus, designed to simulate isotropic pressure and constant volume conditions within the testing range of 4–6 MPa average effective stress. The response of bentonite during thermal loading at temperatures up to 200 °C was investigated, extending the previously considered temperature range. The results provide details of bentonite’s intrinsic permeability, total stress, swelling pressure and porewater pressure during thermal cycles. We find that bentonite’s hydraulic properties are sensitive to thermal loading and the type of imposed boundary condition. However, the permeability change is not large and can mostly be accounted for by water viscosity changes. Thus, under 150 °C, temperature has a minimal impact on bentonite’s hydraulic permeability.

  8. Carbon Nanotube Electron Sources: From Electron Beams to Energy Conversion and Optophononics

    OpenAIRE

    Alireza Nojeh

    2014-01-01

    Carbon nanotubes have a host of properties that make them excellent candidates for electron emitters. A significant amount of research has been conducted on nanotube-based field-emitters over the past two decades, and they have been investigated for devices ranging from flat-panel displays to vacuum tubes and electron microscopes. Other electron emission mechanisms from carbon nanotubes, such as photoemission, secondary emission, and thermionic emission, have also been studied, although to a ...

  9. Carbonate aquifers

    Science.gov (United States)

    Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

    2012-01-01

    Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

  10. Permeability Estimation of Grosmont Formation, Alberta, Canada by Statistically Combining Well-logs and Core Measurements

    Science.gov (United States)

    Choi, J.; Keehm, Y.

    2011-12-01

    Permeability estimation in carbonate reservoirs is quite challenging since they are very heterogeneous. Moreover, the amount of core measurement data is commonly limited. In this paper, we present permeability maps for Grosmont formation in Canada with very limited permeability data, using bi-variated probability density function (porosity and permeability) conditioned to geological information. Grosmont formation consists of four units: Lower Grosmont (LG); Upper Grosmont (UG1); Upper Grosmont 2 (UG2); and Upper Grosmont 3 (UG3). From the previous studies, UG2 and UG3 are more promising reservoir units since they have larger porosity and permeability with vuggy pores and fractures by diagenesis (dolomitization and karstification). Thus, we applied our method to these two units. We first investigated core measurement data (porosity and permeability) and compared them to local geological aspects, such as the degree of diagenesis and vicinity of unconformity. Then we could divide the study area into 6 groups, and we established a bivariated probability density function (pdf) for each group and each unit (total of 12 pdfs) with core measurements of porosity and permeability. In the next step, we created porosity maps using well-log data for UG2 and UG3. The final step is to generate permeability maps for UG2 and UG3 by drawing a permeability value from the bivariated pdf conditioned to porosity. The final results show more realistic permeability maps for Grosmont formation when compared to conventional kriging results. Moreover, the strengths of this approach is (1) that it can use geological information and (2) that it can handle the variability of permeability, which can be naturally occurred in carbonate reservoirs. Acknowledgement: This work was supported by the Energy Resources R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2008RER11P0430302009).

  11. Integrated petrophysical and reservoir characterization workflow to enhance permeability and water saturation prediction

    Science.gov (United States)

    Al-Amri, Meshal; Mahmoud, Mohamed; Elkatatny, Salaheldin; Al-Yousef, Hasan; Al-Ghamdi, Tariq

    2017-07-01

    Accurate estimation of permeability is essential in reservoir characterization and in determining fluid flow in porous media which greatly assists optimize the production of a field. Some of the permeability prediction techniques such as Porosity-Permeability transforms and recently artificial intelligence and neural networks are encouraging but still show moderate to good match to core data. This could be due to limitation to homogenous media while the knowledge about geology and heterogeneity is indirectly related or absent. The use of geological information from core description as in Lithofacies which includes digenetic information show a link to permeability when categorized into rock types exposed to similar depositional environment. The objective of this paper is to develop a robust combined workflow integrating geology and petrophysics and wireline logs in an extremely heterogeneous carbonate reservoir to accurately predict permeability. Permeability prediction is carried out using pattern recognition algorithm called multi-resolution graph-based clustering (MRGC). We will bench mark the prediction results with hard data from core and well test analysis. As a result, we showed how much better improvements are achieved in the permeability prediction when geology is integrated within the analysis. Finally, we use the predicted permeability as an input parameter in J-function and correct for uncertainties in saturation calculation produced by wireline logs using the classical Archie equation. Eventually, high level of confidence in hydrocarbon volumes estimation is reached when robust permeability and saturation height functions are estimated in presence of important geological details that are petrophysically meaningful.

  12. Modeling stress/strain-dependent permeability changes for deep geoenergy applications

    Science.gov (United States)

    Rinaldi, Antonio Pio; Rutqvist, Jonny

    2016-04-01

    Rock permeability is a key parameter in deep geoenergy systems. Stress and strain changes induced at depth by fluid injection or extraction may substantially alter the rock permeability in an irreversible way. With regard to the geoenergies, some applications require the permeability to be enhanced to improve productivity. The rock permeability is generally enhanced by shearing process of faults and fractures (e.g. hydroshearing for Enhanced and Deep Geothermal Systems), or the creation of new fractures (e.g. hydrofracturing for shale gas). However, such processes may, at the same time, produce seismicity that can be felt by the local population. Moreover, the increased permeability due to fault reactivation may pose at risk the sealing capacity of a storage site (e.g. carbon sequestration or nuclear waste disposal), providing then a preferential pathway for the stored fluids to escape at shallow depth. In this work we present a review of some recent applications aimed at understanding the coupling between stress (or strain) and permeability. Examples of geoenergy applications include both EGS and CO2 sequestration. To investigate both "wanted" and "unwanted" effects, THM simulations have been carried out with the TOUGH-FLAC simulator. Our studies include constitutive equations relating the permeability to mean effective stress, effective normal stress, volumetric strain, as well as accounting for permeability variation as related to fault/fracture reactivation. Results show that the geomechanical effects have a large role in changing the permeability, hence affecting fluids leakage, reservoir enhancement, as well as the induced seismicity.

  13. Ultra High Energy Density Cathodes with Carbon Nanotubes

    Science.gov (United States)

    2013-12-10

    34Enhanced Capacity and Rate Capability of Carbon Nanotube Based Anodes with Titanium Contacts for Lithium Ion Batteries," ACS Nano, vol. 4, pp. 6121- 6131...2010/10/26 2010. [2] S. L. Chou, et al., "Silicon/Single-Walled Carbon Nanotube Composite Paper as a Flexible Anode Material for Lithium Ion...AFRL-RV-PS- AFRL-RV-PS- TR-2013-0170 TR-2013-0170 ULTRA HIGH ENERGY DENSITY CATHODES WITH CARBON NANOTUBES Brian J. Landi, et al. Rochester

  14. Capillary permeability in adipose tissue

    DEFF Research Database (Denmark)

    Paaske, W P; Nielsen, S L

    1976-01-01

    of about 7 ml/100 g-min. This corresponds to a capillary diffusion capacity of 2.0 ml/100 g-min which is half the value reported for vasodilated skeletal muscle having approximately twice as great capillary surface area. Thus, adipose tissue has about the same capillary permeability during slight metabolic...

  15. Committee neural network model for rock permeability prediction

    Science.gov (United States)

    Bagheripour, Parisa

    2014-05-01

    Quantitative formulation between conventional well log data and rock permeability, undoubtedly the most critical parameter of hydrocarbon reservoir, could be a potent tool for solving problems associated with almost all tasks involved in petroleum engineering. The present study proposes a novel approach in charge of the quest for high-accuracy method of permeability prediction. At the first stage, overlapping of conventional well log data (inputs) was eliminated by means of principal component analysis (PCA). Subsequently, rock permeability was predicted from extracted PCs using multi-layer perceptron (MLP), radial basis function (RBF), and generalized regression neural network (GRNN). Eventually, a committee neural network (CNN) was constructed by virtue of genetic algorithm (GA) to enhance the precision of ultimate permeability prediction. The values of rock permeability, derived from the MPL, RBF, and GRNN models, were used as inputs of CNN. The proposed CNN combines results of different ANNs to reap beneficial advantages of all models and consequently producing more accurate estimations. The GA, embedded in the structure of the CNN assigns a weight factor to each ANN which shows relative involvement of each ANN in overall prediction of rock permeability from PCs of conventional well logs. The proposed methodology was applied in Kangan and Dalan Formations, which are the major carbonate reservoir rocks of South Pars Gas Field-Iran. A group of 350 data points was used to establish the CNN model, and a group of 245 data points was employed to assess the reliability of constructed CNN model. Results showed that the CNN method performed better than individual intelligent systems performing alone.

  16. Quantifying Evaporation in a Permeable Pavement System

    Science.gov (United States)

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  17. Permeability of Non-Crimp Fabric Preforms

    NARCIS (Netherlands)

    Loendersloot, Richard; Lomov, Stepan V.

    2011-01-01

    Experimental permeability data of non-crimp fabrics (NCFs) is discussed in this chapter. The chapter starts with a general introduction on permeability, followed by a discussion on experimental permeability data. The infl uence of geometrical features of the textile architecture, in particular the s

  18. Different Methods of Predicting Permeability in Shale

    DEFF Research Database (Denmark)

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Krogsbøll, Anette

    Permeability is often very difficult to measure or predict in shale lithology. In this work we are determining shale permeability from consolidation tests data using Wissa et al., (1971) approach and comparing the results with predicted permeability from Kozeny’s model. Core and cuttings materials...

  19. Permeability of Dental Adhesives - A SEM Assessment.

    Science.gov (United States)

    Malacarne-Zanon, Juliana; de Andrade E Silva, Safira M; Wang, Linda; de Goes, Mario F; Martins, Adriano Luis; Narvaes-Romani, Eliene O; Anido-Anido, Andrea; Carrilho, Marcela R O

    2010-10-01

    To morphologically evaluate the permeability of different commercial dental adhesives using scanning electron microscopy. SEVEN ADHESIVE SYSTEMS WERE EVALUATED: one three-step system (Scotchbond Multi-Purpose - MP); one two-step self-etching primer system (Clearfil SE Bond - SE); three two-step etch-and-rinse systems (Single Bond 2 - SB; Excite - EX; One-Step - OS); and two single-step self-etching adhesives (Adper Prompt - AP; One-Up Bond F - OU). The mixture of primer and bond agents of the Clearfil SE Bond system (SE-PB) was also tested. The adhesives were poured into a brass mold (5.8 mm x 0.8 mm) and light-cured for 80 s at 650 mW/cm2. After a 24 h desiccation process, the specimens were immersed in a 50% ammoniac silver nitrate solution for tracer permeation. Afterwards, they were sectioned in ultra-fine slices, carbon-coated, and analyzed under backscattered electrons in a scanning electron microscopy. MP and SE showed slight and superficial tracer permeation. In EX, SB, and OS, permeation extended beyond the inner superficies of the specimens. SE-PB did not mix well, and most of the tracer was precipitated into the primer agent. In AP and OU, "water-trees" were observed all over the specimens. Different materials showed distinct permeability in aqueous solution. The extent of tracer permeation varied according to the composition of each material and it was more evident in the more hydrophilic and solvated ones.

  20. Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Lawal, Abdulazeez T., E-mail: abdul.lawal@yahoo.com

    2016-01-15

    Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

  1. Permeability of commercial solvents through living human skin

    DEFF Research Database (Denmark)

    Ursin, C; Hansen, C M; Van Dyk, J W;

    1995-01-01

    rate. For other solvents this was not necessary, so the un-normalized data were used. High [3H]water permeation rate also was used as a criterion for "defective" skin samples that gave erroneous permeability rates, especially for solvents having slow permeability. The linearity of the steady state data...... was characterized by calculation of the "percent error of the slope." The following permeability rates (g/m2h) of single solvents were measured: dimethyl sulfoxide (DMSO), 176; N-methyl-2-pyrrolidone, 171; dimethyl acetamide, 107; methyl ethyl ketone, 53; methylene chloride, 24; [3H]water, 14.8; ethanol, 11.......3; butyl acetate, 1.6; gamma-butyrolactone, 1.1; toluene, 0.8; propylene carbonate, 0.7; and sulfolane, 0.2. The effect of [3H]water saturation on the shape of the presteady state portion of the permeation curve was determined and found to be very dependent on the solvent. The permeability of mixtures...

  2. Transport Properties of Carbon-Nanotube/Cement Composites

    NARCIS (Netherlands)

    Han, B.; Yang, Z.; Shi, X.; Yu, X.

    2012-01-01

    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) rei

  3. Carbon Nanotubes as Active Components for Gas Sensors

    Directory of Open Access Journals (Sweden)

    Wei-De Zhang

    2009-01-01

    Full Text Available The unique structure of carbon nanotubes endows them with fantastic physical and chemical characteristics. Carbon nanotubes have been widely studied due to their potential applications in many fields including conductive and high-strength composites, energy storage and energy conversion devices, sensors, field emission displays and radiation sources, hydrogen storage media, and nanometer-sized semiconductor devices, probes, and quantum wires. Some of these applications have been realized in products, while others show great potentials. The development of carbon nanotubes-based sensors has attracted intensive interest in the last several years because of their excellent sensing properties such as high selectivity and prompt response. Carbon nanotube-based gas sensors are summarized in this paper. Sensors based on single-walled, multiwalled, and well-aligned carbon nanotubes arrays are introduced. Modification of carbon nanotubes with functional groups, metals, oxides, polymers, or doping carbon nanotubes with other elements to enhance the response and selectivity of the sensors is also discussed.

  4. Permeability equipment for porous friction surfaces

    Science.gov (United States)

    Standiford, D. L.; Graul, R. A.; Lenke, L. R.

    1985-04-01

    Hydroplaning is the loss of traction between tires and pavement due to the presence of a layer of water. This loss of traction can result in loss of vehicle control. A porous friction surface (PFS) applied over an existing pavement permits the water to drain laterally and vertically away from the tire path, effectively lowering hydroplaning potential. Equipment used to measure pavement drainage (permeability) is discussed with respect to usage on porous friction surface. Background information on hydroplaning, flow theory, and PFS field performance as they are affected by permeability are also presented. Two dynamic test devices and four static devices are considered for measuring PFS permeability. Permeability tests are recommended to measure PFS permeability for maintenance purposes and construction control. Dynamic devices cited could possibly estimate hydroplaning potential; further research must be done to determine this. Permeability devices cannot be used to accurately estimate friction of a pavement surface, however, decreased permeability of a pavement infers a decrease in friction.

  5. On the permeability of fractal tube bundles

    CERN Document Server

    Zinovik, I

    2011-01-01

    The permeability of a porous medium is strongly affected by its local geometry and connectivity, the size distribution of the solid inclusions and the pores available for flow. Since direct measurements of the permeability are time consuming and require experiments that are not always possible, the reliable theoretical assessment of the permeability based on the medium structural characteristics alone is of importance. When the porosity approaches unity, the permeability-porosity relationships represented by the Kozeny-Carman equations and Archie's law predict that permeability tends to infinity and thus they yield unrealistic results if specific area of the porous media does not tend to zero. The goal of this paper is an evaluation of the relationships between porosity and permeability for a set of fractal models with porosity approaching unity and a finite permeability. It is shown that the two-dimensional foams generated by finite iterations of the corresponding geometric fractals can be used to model poro...

  6. Electrical conductivity of metal–carbon nanotube structures: Effect of length and doping

    Indian Academy of Sciences (India)

    R Nigam; S Habeeb; A Priyadarshi; N Jaggi

    2014-08-01

    The electrical properties of asymmetric metal–carbon nanotube (CNT) structures have been studied using density functional theory and non-equilibrium Green’s function method with Atomistix tool kit. The models with asymmetric metal contacts and carbon nanotube bear resemblance to experimental set-ups. The study shows the effect of varying length of carbon nanotube on electronic transmission and conductance of various structures. The effects of silicon doping on CNT-based structures have also been studied. The conductance of structure with longer CNT is more compared with shorter CNT. Silicon doping increases the conductivity of carbon nanotube-based structure.

  7. Effects of Extremely Low Frequency Electromagnetic Fields on Vascular Permeability of Circumventricular Organs in the Adult Rat

    Science.gov (United States)

    Gutiérrez-Mercado, Y. K.; Cañedo-Dorantes, L.; Bañuelos-Pineda, J.; Serrano-Luna, G.; Feria-Velasco, A.

    2008-08-01

    The present work deals with the effects of extremely low frequency electromagnetic fields (ELF-EMF) on blood vessels permeability to non liposoluble substances of the circumventricular organs (CVO) of adult rats. Male Wistar adult rats were exposed to ELF-EMF and vascular permeability to colloidal carbon was investigated with the use of histological techniques. Results were compared to corresponding data from sham-exposed and control groups of animals. Exposure to ELF-EMF increased the CVO vascular permeability to colloidal carbon intravascularly injected, particularly in the subfornical organ, the median eminence, the pineal gland and the area postrema.

  8. A Thermal Model for Carbon Nanotube Interconnects

    Directory of Open Access Journals (Sweden)

    Clay Mayberry

    2013-04-01

    Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  9. Structural determinants of glomerular permeability.

    Science.gov (United States)

    Deen, W M; Lazzara, M J; Myers, B D

    2001-10-01

    Recent progress in relating the functional properties of the glomerular capillary wall to its unique structure is reviewed. The fenestrated endothelium, glomerular basement membrane (GBM), and epithelial filtration slits form a series arrangement in which the flow diverges as it enters the GBM from the fenestrae and converges again at the filtration slits. A hydrodynamic model that combines morphometric findings with water flow data in isolated GBM has predicted overall hydraulic permeabilities that are consistent with measurements in vivo. The resistance of the GBM to water flow, which accounts for roughly half that of the capillary wall, is strongly dependent on the extent to which the GBM surfaces are blocked by cells. The spatial frequency of filtration slits is predicted to be a very important determinant of the overall hydraulic permeability, in keeping with observations in several glomerular diseases in humans. Whereas the hydraulic resistances of the cell layers and GBM are additive, the overall sieving coefficient for a macromolecule (its concentration in Bowman's space divided by that in plasma) is the product of the sieving coefficients for the individual layers. Models for macromolecule filtration reveal that the individual sieving coefficients are influenced by one another and by the filtrate velocity, requiring great care in extrapolating in vitro observations to the living animal. The size selectivity of the glomerular capillary has been shown to be determined largely by the cellular layers, rather than the GBM. Controversial findings concerning glomerular charge selectivity are reviewed, and it is concluded that there is good evidence for a role of charge in restricting the transmural movement of albumin. Also discussed is an effect of albumin that has received little attention, namely, its tendency to increase the sieving coefficients of test macromolecules via steric interactions. Among the unresolved issues are the specific contributions of the

  10. The Membrane Permeability Outcome study.

    Science.gov (United States)

    Locatelli, Francesco; Cavalli, Andrea; Manzoni, Celestina; Pontoriero, Giuseppe

    2011-01-01

    Many observational studies have consistently shown that high-flux hemodialysis has positive effects on the survival and morbidity of uremic patients when compared with low-flux hemodialysis. However, the HEMO study, a randomized trial designed to evaluate the effect of membrane permeability on patient survival, showed only an 8% non-statistically significant reduction of mortality, albeit a secondary analysis suggested an advantage for high-flux membranes in certain patient subgroups. The prospective, randomized Membrane Permeability Outcome (MPO) study investigated the impact of membrane permeability on survival in incident hemodialysis patients who had low albumin (≤4 g/dl) and normal albumin ( >4 g/dl) as separate randomization groups. Patients with serum albumin ≤4 g/dl had significantly better survival rates in the high-flux group compared with the low-flux group (p = 0.032). Moreover, a post-hoc secondary analysis showed that high-flux membranes may significantly improve survival in diabetic patients. No difference was found in patients with normal albumin levels. Considering the increasing number of dialysis patients with low serum albumin levels and with diabetes, the relevance of the MPO study led to the publication of a position statement by the European Renal Best Practice Advisory Board. This board strongly recommended that high-flux hemodialysis should be used for high-risk patients and, with a lower degree of evidence, even also for low-risk subjects due to the substantial reduction in β(2)-microglobulin levels observed in the high-flux group. Copyright © 2011 S. Karger AG, Basel.

  11. Gravity Current in Horizontal Porous Media with A Permeability Gradient

    Science.gov (United States)

    Zheng, Zhong; Tsai, Peichun; Al-Housseiny, Talal; Stone, Howard; Complex Fluid Group Team

    2011-11-01

    We study the influence of a power-law porosity and permeability gradient on the front propagation of a gravity current in an unconfined porous media. We neglect mass transfer and surface tension on the interface. A similarity solution is found for the propagating front, which is different from the homogeneous case. Experiments have been performed using liquid pushing air in a Hele-Shaw cell with a constant gradient in gap thickness in the vertical direction. We measure the speed of the front and the shape of the interface. We observe a third layer of trapped air in the region where the permeability is low, while it appears that the propagating front still satisfies the similarity solution with a modified coefficient. This work is supported by a funding from Carbon Mitigation Initiative at Princeton University

  12. Permeability of normal versus carious dentin.

    Science.gov (United States)

    Pashley, E L; Talman, R; Horner, J A; Pashley, D H

    1991-10-01

    Although a number of reports have been published demonstrating that carious dentin is less permeable than normal dentin, these reports have been qualitative rather than quantitative. The purpose of this in vitro study was to apply a quantitative technique to the study of the permeability of carious human teeth before and after excavation, before and after removal of the smear layer and before and after preparation of a control cavity of similar size and depth in normal dentin subjected to the same measurements, for comparative purposes. Dentin permeability was measured as a hydraulic conductance. The permeability values measured at each step in the protocol were expressed as a percent of the maximum permeability of both cavities, permitting each tooth the serve as its own control. Carious lesions exhibited a slight degree of permeability (2.3 +/- 0.6% of controls) which remained unchanged after excavation of the lesions. Removal of the smear layer in the excavated carious lesions increased the permeability significantly to 6.9 +/- 3.2%. Preparation of a control cavity of the same area and depth increased the permeability slightly. Removal of its smear layer increased the permeability of the dentin 91%. These results confirm previous qualitative studies that carious dentin, even after excavation and removal of the smear layer has a very low permeability.

  13. Groundwater protection from cadmium contamination by permeable reactive barrier in Qian'an of Jilin, China

    Institute of Scientific and Technical Information of China (English)

    Alkali Mohammed; Changlai XIAO; Chao DU

    2008-01-01

    This research studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable reactive barrier (PRB). In particular, it has been considered the case of a PAB used to protect a lake or downstream from Cd (Ⅱ) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing lake or downstream pollution for several months.

  14. Design and fabrication of carbon nanotube field-emission cathode with coaxial gate and ballast resistor.

    Science.gov (United States)

    Sun, Yonghai; Yeow, John T W; Jaffray, David A

    2013-10-25

    A low density vertically aligned carbon nanotube-based field-emission cathode with a ballast resistor and coaxial gate is designed and fabricated. The ballast resistor can overcome the non-uniformity of the local field-enhancement factor at the emitter apex. The self-aligned fabrication process of the coaxial gate can avoid the effects of emitter tip misalignment and height non-uniformity.

  15. Medium scale carbon nanotube thin film integrated circuits on flexible plastic substrates

    Science.gov (United States)

    Rogers, John A; Cao, Qing; Alam, Muhammad; Pimparkar, Ninad

    2015-02-03

    The present invention provides device components geometries and fabrication strategies for enhancing the electronic performance of electronic devices based on thin films of randomly oriented or partially aligned semiconducting nanotubes. In certain aspects, devices and methods of the present invention incorporate a patterned layer of randomly oriented or partially aligned carbon nanotubes, such as one or more interconnected SWNT networks, providing a semiconductor channel exhibiting improved electronic properties relative to conventional nanotubes-based electronic systems.

  16. Electro-induced mechanical and thermal responses of carbon nanotube fibers.

    Science.gov (United States)

    Meng, Fancheng; Zhang, Xiaohua; Li, Ru; Zhao, Jingna; Xuan, Xiaohui; Wang, Xinhao; Zou, Jingyun; Li, Qingwen

    2014-04-23

    The electromechanical and electrothermal responses of carbon nanotube fibers provide new ways to use energy conversion, including the modulation of assembly structures by alternative densification and relaxation. The most efficient way to strengthen the tensile strength up to 2.32-2.50 GPa is shown as well as a microscale, nanotube-based Chinese calligraphy brush. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Steam-water relative permeability

    Energy Technology Data Exchange (ETDEWEB)

    Ambusso, W.; Satik, C.; Home, R.N. [Stanford Univ., CA (United States)

    1997-12-31

    A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

  18. Vortex rings impinging on permeable boundaries

    Science.gov (United States)

    Mujal-Colilles, Anna; Dalziel, Stuart B.; Bateman, Allen

    2015-01-01

    Experiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring impinging four different reticulated foams (with permeability k ˜ 26 - 85 × 10-8 m2) and a solid boundary. Results show how permeability affects the stretching phenomena of the vortex ring and the formation and evolution of the secondary vortex ring with opposite sign. Moreover, permeability also affects the macroscopic no-slip boundary condition found on the solid boundary, turning it into an apparent slip boundary condition for the most permeable boundary. The apparent slip-boundary condition and the flux exchange between the ambient fluid and the foam are jointly responsible for both the modified formation of the secondary vortex and changes on the vortex ring diameter increase.

  19. Clogging in permeable concrete: A review.

    Science.gov (United States)

    Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

    2017-05-15

    Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Modelling of water permeability in cementitious materials

    DEFF Research Database (Denmark)

    Guang, Ye; Lura, Pietro; van Breugel, K.

    2006-01-01

    This paper presents a network model to predict the permeability of cement paste from a numerical simulation of its microstructure. Based on a linked list pore network structure, the effective hydraulic conductivity is estimated and the fluid flow is calculated according to the Hagen-Poiseuille law....... The pressure gradient at all nodes is calculated with the Gauss elimination method and the absolute permeability of the pore network is calculated directly from Darcy's law. Finally, the permeability model is validated by comparison with direct water permeability measurements. According to this model......, the predicted permeability of hydrating cement pastes is extremely sensitive to the particle size distribution of the cement and especially to the minimum size of the cement particles. Both in simulations and experiments, the permeability of cement pastes is mainly determined by the critical diameter...

  1. Characterization of preform permeability and flow behavior for liquid composite molding

    Science.gov (United States)

    Sommerlot, Stephen Joseph

    Preform characterization is an important step in the processing of high-performance parts with liquid composite molding. A better understanding of preform compressibility and permeability creates more accurate process models, ultimately leading to high-quality finished composites. Without characterization, mold design and processing parameters are subject to guess-work and ad hoc optimization methods, which can result in poor infusions and inconsistent part quality. In this study, a complex architecture fiber reinforcement was characterized in compaction and permeability for liquid composite molding. Preforms of a four-harness satin carbon fabric were assembled with and without a novel inter-layer tackifier for experimentation. Compaction and permeability were measured to investigate the effects of the tackifier system, debulking, preform layup, and other processing parameters. Permeability and flow behavior was measured through saturated and unsaturated techniques, including investigations of fluid effects and high-flow rate infusions. The tackifier was seen to decrease permeability in both saturated and unsaturated cases, while notably influencing the orientation of first principal permeability. Tackified preforms also displayed a sensitivity to fluid type that non-tackified samples did not. Experimentally derived permeability was also used to generate numerical mold fill simulations of radially injected infusions, which produced favorable results.

  2. Permeability of Electrospun Superhydrophobic Nanofiber Mats

    Directory of Open Access Journals (Sweden)

    Sarfaraz U. Patel

    2012-01-01

    Full Text Available This paper discusses the fabrication and characterization of electrospun nanofiber mats made up of poly(4-methyl-1-pentene polymer. The polymer was electrospun in different weight concentrations. The mats were characterized by their basis weight, fiber diameter distribution, contact angles, contact angle hysteresis, and air permeability. All of the electrospun nonwoven fiber mats had water contact angles greater than 150 degrees making them superhydrophobic. The permeabilities of the mats were empirically fitted to the mat basis weight by a linear relation. The experimentally measured air permeabilities were significantly larger than the permeabilities predicted by the Kuwabara model for fibrous media.

  3. Vascular permeability in cerebral cavernous malformations.

    Science.gov (United States)

    Mikati, Abdul G; Khanna, Omaditya; Zhang, Lingjiao; Girard, Romuald; Shenkar, Robert; Guo, Xiaodong; Shah, Akash; Larsson, Henrik B W; Tan, Huan; Li, Luying; Wishnoff, Matthew S; Shi, Changbin; Christoforidis, Gregory A; Awad, Issam A

    2015-10-01

    Patients with the familial form of cerebral cavernous malformations (CCMs) are haploinsufficient for the CCM1, CCM2, or CCM3 gene. Loss of corresponding CCM proteins increases RhoA kinase-mediated endothelial permeability in vitro, and in mouse brains in vivo. A prospective case-controlled observational study investigated whether the brains of human subjects with familial CCM show vascular hyperpermeability by dynamic contrast-enhanced quantitative perfusion magnetic resonance imaging, in comparison with CCM cases without familial disease, and whether lesional or brain vascular permeability correlates with CCM disease activity. Permeability in white matter far (WMF) from lesions was significantly greater in familial than in sporadic cases, but was similar in CCM lesions. Permeability in WMF increased with age in sporadic patients, but not in familial cases. Patients with more aggressive familial CCM disease had greater WMF permeability compared to those with milder disease phenotype, but similar lesion permeability. Subjects receiving statin medications for routine cardiovascular indications had a trend of lower WMF, but not lesion, permeability. This is the first demonstration of brain vascular hyperpermeability in humans with an autosomal dominant disease, as predicted mechanistically. Brain permeability, more than lesion permeability, may serve as a biomarker of CCM disease activity, and help calibrate potential drug therapy.

  4. Modeling flow in porous media with double porosity/permeability: Mathematical model, properties, and analytical solutions

    CERN Document Server

    Nakshatrala, K B; Ballarini, R

    2016-01-01

    Geo-materials such as vuggy carbonates are known to exhibit multiple spatial scales. A common manifestation of spatial scales is the presence of (at least) two different scales of pores, which is commonly referred to as double porosity. To complicate things, the pore-network at each scale exhibits different permeability, and these networks are connected through fissure and conduits. Although some models are available in the literature, they lack a strong theoretical basis. This paper aims to fill this lacuna by providing the much needed theoretical foundations of the flow in porous media which exhibit double porosity/permeability. We first obtain a mathematical model for double porosity/permeability using the maximization of rate of dissipation hypothesis, and thereby providing a firm thermodynamic underpinning. We then present, along with mathematical proofs, several important mathematical properties that the solutions to the double porosity/permeability model satisfy. These properties are important in their...

  5. The effects of porosity and permeability on fluid flow and heat transfer of multi walled carbon nano-tubes suspended in oil (MWCNT/Oil nano-fluid) in a microchannel filled with a porous medium

    Science.gov (United States)

    Nojoomizadeh, Mehdi; Karimipour, Arash

    2016-10-01

    The forced convection heat transfer and laminar flow in a two-dimensional microchannel filled with a porous medium is numerically investigated. The nano-particles which have been used are multi walled carbon nano-tubes (MWCNT) suspended in oil as the based fluid. The assumption of no-slip condition between the base fluid and nano-particles as well as the thermal equilibrium between them allows us to study the nanofluid in a single phase. The nanofluid flow through the microchannel has been modeled using the Darcy-Forchheimer equation. It is also assumed that there is a thermal equilibrium between the solid phase and the nanofluid for energy transfer. The walls of the microchannel are under the influence of a fluctuating heat flux. Also, the slip velocity boundary condition has been assumed along the walls. The effects of Darcy number, porosity and slip coefficients and Reynolds number on the velocity and temperature profiles and Nusselt number will be studied in this research.

  6. 气体透过碳膜的非平衡动力学模拟研究%Non-equilibrium Molecular Dynamics Simulation on Pure Gas Permeability Through Carbon Membranes

    Institute of Scientific and Technical Information of China (English)

    王淑梅; 于养信; 高光华

    2006-01-01

    The permeation of various pure gas (H2, He, Ne, CH4 and Ar) through carbon membranes is investigated using a dual control volume grand canonical molecular dynamics method. A two-dimensional slit pore is employed instead of the one-dimensional pore. Compared with the experiments, simulation results show that the improvement of pore model is very necessary. The effects of membrane thickness, pore width and temperature on gas permeance and ideal separation factor are also discussed. Results show that gas permeates through membrane according to Knudsen diffusion in large pore, while Knudsen diffusion is accompanied by molecular sieving in small pore. Moreover, methane is easily adsorbed on the membrane surface due to strong attractive interactions of membrane and shows higher permeance than that of Knudsen flow. In addition, it is noted that when membrane thickness is thin enough the permeance of gas does not decrease with the increase of membrane thickness due to the strong adsorption until membrane resistance becomes dominant.

  7. Carbon nanotubes in neuroregeneration and repair.

    Science.gov (United States)

    Fabbro, Alessandra; Prato, Maurizio; Ballerini, Laura

    2013-12-01

    In the last decade, we have experienced an increasing interest and an improved understanding of the application of nanotechnology to the nervous system. The aim of such studies is that of developing future strategies for tissue repair to promote functional recovery after brain damage. In this framework, carbon nanotube based technologies are emerging as particularly innovative tools due to the outstanding physical properties of these nanomaterials together with their recently documented ability to interface neuronal circuits, synapses and membranes. This review will discuss the state of the art in carbon nanotube technology applied to the development of devices able to drive nerve tissue repair; we will highlight the most exciting findings addressing the impact of carbon nanotubes in nerve tissue engineering, focusing in particular on neuronal differentiation, growth and network reconstruction.

  8. Detection of gas atoms with carbon nanotubes

    Science.gov (United States)

    Arash, B.; Wang, Q.

    2013-01-01

    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  9. Semiconductor nanorod-carbon nanotube biomimetic films for wire-free photostimulation of blind retinas.

    Science.gov (United States)

    Bareket, Lilach; Waiskopf, Nir; Rand, David; Lubin, Gur; David-Pur, Moshe; Ben-Dov, Jacob; Roy, Soumyendu; Eleftheriou, Cyril; Sernagor, Evelyne; Cheshnovsky, Ori; Banin, Uri; Hanein, Yael

    2014-11-12

    We report the development of a semiconductor nanorod-carbon nanotube based platform for wire-free, light induced retina stimulation. A plasma polymerized acrylic acid midlayer was used to achieve covalent conjugation of semiconductor nanorods directly onto neuro-adhesive, three-dimensional carbon nanotube surfaces. Photocurrent, photovoltage, and fluorescence lifetime measurements validate efficient charge transfer between the nanorods and the carbon nanotube films. Successful stimulation of a light-insensitive chick retina suggests the potential use of this novel platform in future artificial retina applications.

  10. In situ permeability modification using gelled polymer systems. Annual report, April 11, 1997--April 10, 1998

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; McCool, C.S.; Heppert, J.A.; Vossoughi, S.; Michnick, M.J.

    1998-09-01

    Results from a research program on the application of gelled polymer technology for in situ permeability modification are presented in this report. The objective of this technology when used with displacement processes such as waterflooding is to reduce the permeability in fractures and/or high permeability matrix zones to improve volumetric sweep efficiency of the displacement process. In production wells, the objective is to reduce water influx. The research program focused on five areas: Gel treatment in fractured systems; Gel treatment in carbonate rocks; In-depth placement of gels; Gel systems for application in carbon dioxide flooding; and Gel treatment in production wells. The research program is primarily an experimental program directed toward improving the understanding of gelled polymer systems and how these systems can be used to increase oil recovery from petroleum reservoirs. A summary of progress for research conducted in the second 12 month period of a 28 month program is described.

  11. In situ permeability modification using gelled polymer systems. Topical report, June 10, 1996--April 10, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.W.; Willhite, G.P.; McCool, C.S.; Heppert, J.A.; Vossoughi, S.

    1997-10-01

    Results from a research program on the application of gelled polymer technology for in situ permeability modification are presented in this report. The objective of this technology when used with displacement processes such as waterflooding is to reduce the permeability in fractures and/or high permeability matrix zones to improve volumetric sweep efficiency of the displacement process. In production wells, the objective is to reduce water influx. The research program is focused on five areas: gel treatment in fractured systems; gel treatment in carbonate rocks; in-depth placement of gels; gel systems for application in carbon dioxide flooding; and gel treatment in production wells. The research program is primarily an experimental program directed at improving the understanding of gelled polymer systems and how these systems can be used to increase oil recovery from petroleum reservoirs. A summary of progress for research conducted in the first 10 months of a 28 month program is described in the following sections.

  12. Experimental Measurement of Relative Permeability Functions for Fuel Cell GDL Materials

    KAUST Repository

    Hussaini, Irfan

    2009-01-01

    Gas diffusion layer in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex-situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented. Significant departure from the generally assumed cubic function of saturation is observed. ©The Electrochemical Society.

  13. Image-based relative permeability upscaling from the pore scale

    Science.gov (United States)

    Norouzi Apourvari, Saeid; Arns, Christoph H.

    2016-09-01

    High resolution images acquired from X-ray μ-CT are able to map the internal structure of porous media on which multiphase flow properties can be computed. While the resolution of a few micrometers may be sufficient for capturing the pore space of many sandstones, most carbonates exhibit a large amount of microporosity; pores which are below the image resolution and are not resolved at specific resolution. Neglecting the effect of micropores on fluid flow and transport properties of these rocks can cause erroneous results in particular at partial saturations. Current image-based pore scale models typically only consider macropores for simulating fluid flow. In this paper, we quantify the effect of microporosity on the effective permeability of the wetting phase for heterogeneous model structures with varying amount of micro-to-macro porosity. A multi-scale numerical approach is proposed to couple an average effect of micropores with an explicit representation of macropores. The Brinkman equation is solved using a lattice Boltzmann formulation to facilitate the coupling of Darcy and Stokes equations in micropores and macropores, respectively. The results show good agreement between the fine scale solution and the results of the upscaled models in which microporous regions are homogenised. The paper analyses in particular the choice of the momentum sink parameter at low wetting phase saturations. It is shown that this parameter can be found using either a flux-based calculation of permeability of microporous regions or chosen purely on the basis of the effective permeability of these regions.

  14. Intercomparison on measurement of water vapour permeability

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard

    Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001).......Three different materials are tested - hard woodfibre board - damp proof course - underlay for roofing The water vapour permeability has been measured according to EN ISO 12572 (2001)....

  15. Accurate determination of characteristic relative permeability curves

    Science.gov (United States)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  16. Effects of pore-scale precipitation on permeability and flow

    Science.gov (United States)

    Noiriel, Catherine; Steefel, Carl I.; Yang, Li; Bernard, Dominique

    2016-09-01

    The effects of calcite precipitation on porous media permeability and flow were evaluated with a combined experimental and modeling approach. X-ray microtomography images of two columns packed with glass beads and calcite (spar crystals) or aragonite (Bahamas ooids) injected with a supersaturated solution (log Ω = 1.42) were processed in order to calculate rates of calcite precipitation with a spatial resolution of 4.46 μm. Identification and localization of the newly precipitated crystals on the 3D images was performed and results used to calculate the crystal growth rates and velocities. The effects of carbonate precipitation were also evaluated in terms of the integrated precipitation rate over the length of the column, crystal shape, surface area and pore roughness changes. While growth was epitaxial on calcite spar, calcite rhombohedra formed on glass beads and clusters of polyhedrons formed on aragonite ooids. Near the column inlet, calcite precipitation occurred preferentially on carbonate grains compared to glass beads, with almost 100% of calcite spar surface area covered by new crystals versus 92% in the case of aragonite and 11% in the case of glass beads. Although the experimental chemistry and flow boundary conditions in the two columns were similar, their porosity-permeability evolution was different because the nucleation and subsequent crystal growth on the two substrates (i.e., calcite spar and aragonite ooids) was very different. The impact of mineral precipitation on pore-scale flow and permeability was evaluated using a pore-scale Stokes solver that accounted for the changes in pore geometry. For similar magnitude reductions in porosity, the decrease in permeability was highest within the sample that experienced the greatest increase in pore roughness. Various porous media models were generated to show the impact of different crystal growth patterns and pore roughness changes on flow and permeability-porosity relationship. Under constant flow

  17. Permeability Tests on Eastern Scheldt Sand

    DEFF Research Database (Denmark)

    Jakobsen, Kim Parsberg

    The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends on the charact......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...... on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Eastern Scheldt Sand. The permeability is determined by use of a falling head apparatus. Finally the test results are briefly summarised and a relationship between...... void ratio and permeability is established....

  18. Macro fluid analysis of laminated fabric permeability

    Directory of Open Access Journals (Sweden)

    Qiu Li

    2016-01-01

    Full Text Available A porous jump model is put forward to predict the breathability of laminated fabrics by utilizing fluent software. To simplify the parameter setting process, the methods of determining the parameters of jump porous model by means of fabric layers are studied. Also, effects of single/multi-layer fabrics and thickness on breathability are analyzed, indicating that fabric breathability reduces with the increase of layers. Multi-layer fabric is simplified into a single layer, and the fabric permeability is calculated by proportion. Moreover, the change curve of fabric layer and face permeability, as well as the equation between the fabric layer and the face permeability are obtained. Then, face permeability and pressure-jump coefficient parameters setting of porous jump model could be integrated into single parameter (i. e. fabric layers, which simplifies the fluent operation process and realizes the prediction of laminated fabric permeability.

  19. Permeability measurement and control for epoxy composites

    Science.gov (United States)

    Chang, Tsun-Hsu; Tsai, Cheng-Hung; Wong, Wei-Syuan; Chen, Yen-Ren; Chao, Hsien-Wen

    2017-08-01

    The coupling of the electric and magnetic fields leads to a strong interplay in materials' permittivity and permeability. Here, we proposed a specially designed cavity, called the mu cavity. The mu cavity, consisting of a mushroom structure inside a cylindrical resonator, is exclusively sensitive to permeability, but not to permittivity. It decouples materials' electromagnetic properties and allows an accurate measurement of the permeability. With the help of an epsilon cavity, these two cavities jointly determine the complex permeability and permittivity of the materials at microwave frequencies. Homemade epoxy-based composite materials were prepared and tested. Measurement and manipulation of the permeability and permittivity of the epoxy composites will be shown. The results will be compared with the effective medium theories.

  20. Gas permeability of lanthanum oxycarbide targets for the SPES project

    Energy Technology Data Exchange (ETDEWEB)

    Biasetto, L., E-mail: lisa.biasetto@unipd.it [Università di Padova-Department DTG, Stradella San Nicola 3, I-36100 Vicenza (Italy); Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy); Innocentini, M.D.M.; Chacon, W.S. [Curso de Engenharia Química, Universidade de Ribeirão Preto, 14096-900 Ribeirão Preto, SP (Brazil); Corradetti, S.; Carturan, S. [Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy); Colombo, P. [Università di Padova, Department DII, via Marzolo 9, I-35131 Padova (Italy); Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Andrighetto, A. [Laboratori Nazionali di Legnaro-INFN, V.le dell’Università 2, I-35020 Legnaro (PD) (Italy)

    2013-09-15

    The creation of a porous matrix made of interconnected and permeable paths is a key step for the processing of optimized metal carbide targets in the SPES (Selective Production of Exotic Species) project. Unlike close or non-connected open pores, permeable pores link more efficiently the interior and the surface of target disks, and therefore facilitate the effusion and convection transport mechanisms for a faster extraction of exotic nuclei with short decay times. This work describes the analysis of the interconnected porosity of lanthanum oxycarbide targets through the evaluation of permeability coefficients obtained in argon flow experiments at room and high temperature. Samples were produced by the sacrificial template method using phenolic resin (PR) as source of carbon for the carbothermal reaction of lanthanum oxide, and different amounts of polymethilmetacrylate (PMMA) microbeads as template for the production of porosity. Results showed that conventional targets prepared without sacrificial templates displayed relatively high total porosity (45.6%), but very low permeability coefficients (k{sub 1} = 4.21 × 10{sup −17} m{sup 2} and k{sub 2} = 1.90 × 10{sup −15} m), comparable to other dense ceramic materials. The linear increase in total porosity from 64.8% to 88.9% achieved by the gradual increase of PMMA from 30% to 80 wt.% resulted in a remarkable increase of five orders of magnitude for k{sub 1} (2.36 × 10{sup −12} m{sup 2}) and eight orders for k{sub 2} (7.48 × 10{sup −7} m{sup 2}). The addition of sacrificial fillers was found to be much more efficient to create interconnected and permeable paths in the structure than the carbothermal reduction itself. Preliminary tests with argon flow up to 450 °C revealed that the porous matrix also became more permeable with the increase in the gas temperature due to thermal expansion effects, but the extent of this gain depended on the initial porosity level of the sample.

  1. Nutrient infiltrate concentrations from three permeable pavement types.

    Science.gov (United States)

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP

  2. Compact rock material gas permeability properties

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

    2014-09-15

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens’ permeability evolution is related to the relative particle movements and microcrack closure.

  3. Authigenic mineral formation in fluid permeability zones in the West Siberia Permafrost

    Science.gov (United States)

    Kurchatova, A. N.; Melnikov, V. P.; Rogov, V. V.; Slagoda, E. A.

    2016-06-01

    Basic chemical and mineralogical anomalies in permafrost caused by hydrocarbon migration are considered. Direct evidence for bacterial oxidation of light hydrocarbons, primarily methane, were first obtained in fluid permeability zones in the permafrost as a stepwise formation of authigenic minerals such as iron sulfides and oxides, carbonates, silicates, and gypsum.

  4. Plant actin controls membrane permeability.

    Science.gov (United States)

    Hohenberger, Petra; Eing, Christian; Straessner, Ralf; Durst, Steffen; Frey, Wolfgang; Nick, Peter

    2011-09-01

    The biological effects of electric pulses with low rise time, high field strength, and durations in the nanosecond range (nsPEFs) have attracted considerable biotechnological and medical interest. However, the cellular mechanisms causing membrane permeabilization by nanosecond pulsed electric fields are still far from being understood. We investigated the role of actin filaments for membrane permeability in plant cells using cell lines where different degrees of actin bundling had been introduced by genetic engineering. We demonstrate that stabilization of actin increases the stability of the plasma membrane against electric permeabilization recorded by penetration of Trypan Blue into the cytoplasm. By use of a cell line expressing the actin bundling WLIM domain under control of an inducible promotor we can activate membrane stabilization by the glucocorticoid analog dexamethasone. By total internal reflection fluorescence microscopy we can visualize a subset of the cytoskeleton that is directly adjacent to the plasma membrane. We conclude that this submembrane cytoskeleton stabilizes the plasma membrane against permeabilization through electric pulses. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. A Negative Permeability Material at Red Light

    DEFF Research Database (Denmark)

    Yuan, Hsiao-Kuan; Chettiar, Uday K.; Cai, Wenshan;

    2007-01-01

    A negative permeability in a periodic array of pairs of thin silver strips is demonstrated experimentally for two distinct samples. The effect of the strip surface roughness on negative permeability is evaluated. The first sample, Sample A, is fabricated of thinner strips with a root mean square...... roughness of 7 nm, while Sample B is made of thicker strips with 3-nm roughness. The real part of permeability, μ ′ , is −1 at a wavelength of 770 nm in Sample A and −1.7 at 725 nm in Sample B. Relative to prototypes simulated with ideal strips, larger strip roughness acts to decrease μ ′ by a factor of 7...

  6. Gut Permeability in Autism Spectrum Disorders

    OpenAIRE

    2014-01-01

    ObjectiveTo test whether gut permeability is increased in autism spectrum disorders (ASD) by evaluating gut permeability in a population-derived cohort of children with ASD compared with age- and intelligence quotient-matched controls without ASD but with special educational needs (SEN).Patients and MethodsOne hundred thirty-three children aged 10–14 years, 103 with ASD and 30 with SEN, were given an oral test dose of mannitol and lactulose and urine collected for 6 hr. Gut permeability was a...

  7. Are we ready for spray-on carbon nanotubes?

    OpenAIRE

    Maynard, Andrew D.

    2016-01-01

    Earlier this year, British sculptor, Anish Kapoor was given exclusive rights to use a new spray-on carbon nanotube-based paint. The material, produced by UK-based Surrey NanoSystems and marketed as Vantablack S-VIS, can be applied to a range of surfaces, and absorbs well over 99% of the light that falls onto it. It is claimed to be the world's blackest paint, and there is growing interest in its use in works of art and high-end consumer products. It's easy to see the appeal of Vantablack S-VI...

  8. Are we ready for spray-on carbon nanotubes?

    OpenAIRE

    Maynard, Andrew D.

    2016-01-01

    Earlier this year, British sculptor, Anish Kapoor was given exclusive rights to use a new spray-on carbon nanotube-based paint. The material, produced by UK-based Surrey NanoSystems and marketed as Vantablack S-VIS, can be applied to a range of surfaces, and absorbs well over 99% of the light that falls onto it. It is claimed to be the world's blackest paint, and there is growing interest in its use in works of art and high-end consumer products. It's easy to see the appeal of Vantablack S-VI...

  9. Measurement and Modeling of Sorption-Induced Strain and Permeability Changes in Coal

    Energy Technology Data Exchange (ETDEWEB)

    Eric P. Robertson

    2005-10-01

    Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A., and high-volatile bituminous coal from the Uinta-Piceance basin of Utah, U.S.A. using a newly developed strain measurement apparatus. The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain. The swelling and shrinkage (strain) in the coal samples resulting from the adsorption of carbon dioxide, nitrogen, methane, helium, and a mixture of gases was measured. Sorption-induced strain processes were shown to be reversible and easily modeled with a Langmuir-type equation. Extended Langmuir theory was applied to satisfactorily model strain caused by the adsorption of gas mixtures using the pure gas Langmuir strain constants. The amount of time required to obtain accurate strain data was greatly reduced compared to other strain measurement methods. Sorption-induced changes in permeability were also measured as a function of pres-sure. Cleat compressibility was found to be variable, not constant. Calculated variable cleat-compressibility constants were found to correlate well with previously published data for other coals. During permeability tests, sorption-induced matrix shrinkage was clearly demonstrated by higher permeability values at lower pore pressures while holding overburden pressure constant. Measured permeability data were modeled using three dif-ferent permeability models from the open literature that take into account sorption-induced matrix strain. All three models poorly matched the measured permeability data because they overestimated the impact of measured sorption-induced strain on permeabil-ity. However, by applying an experimentally derived expression to the measured strain data that accounts for the confining overburden pressure, pore pressure, coal type, and gas type, the permeability models were significantly improved.

  10. Variability of permeability with diameter of conduit

    Indian Academy of Sciences (India)

    J A Adegoke; J A Olowofela

    2008-05-01

    An entry length is always observed before laminar flow is achieved in fluid flowing in a conduit. This depends on the Reynolds number of the flow and the degree of smoothness of the conduit. This work examined this region and the point where laminar flow commences in the context of flow through conduit packed with porous material like beads, of known porosity. Using some theoretical assumptions, it is demonstrated that permeability varies from zero at wall-fluid boundary to maximum at mid-stream, creating a permeability profile similar to the velocity profile. An equation was obtained to establish this. We also found that peak values of permeability increase with increasing porosity, and therefore entry length increases with increasing porosity with all other parameters kept constant. A plot of peak permeability versus porosity revealed that they are linearly related.

  11. Effect of temperature on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Kjøller, Claus

    assumptions would be required in order to estimate sandstone permeability based on the Kozeny equation. An effective specific surface area per pore volume for permeability was estimated by using image analysis and pore size distributions as from nuclear magnetic resonance (NMR) transverse relaxation data...... be determined based on the Klinkenberg (1941) procedure, which accounts for effects on permeability of gas slip on the fluid-solid interface by means of several permeability measurements with different pore pressures. A comparison between the equivalent pore sizes as estimated using the Kozeny equation...... at 80°C than at 20°C; at 80°C the main effect might be due to an alteration of pore fluid rheology, whereas at 20°C particles might be filtered in pore constrictions. DLVO theory (Derjaguin and Landau (1941); Verwey and Overbeek (1948)) was used to compare effects of temperature and salinity on surface...

  12. Measuring Permeability of Composite Cryotank Laminants

    Science.gov (United States)

    Oliver, Stanley T.; Selvidge, Shawn; Watwood, Michael C.

    2004-01-01

    This paper describes a test method developed to identify whether certain materials and material systems are suitable candidates for large pressurized reusable cryogenic tanks intended for use in current and future manned launch systems. It provides a quick way to screen numerous candidate materials for permeability under anticipated loading environments consistent with flight conditions, as well as addressing reusability issues. cryogenic tank, where the major design issue was hydrogen permeability. It was successfully used to evaluate samples subjected to biaxial loading while maintaining test temperatures near liquid hydrogen. After each sample was thermally preconditioned, a cyclic pressure load was applied to simulate the in-plane strain. First permeability was measured while a sample was under load. Then the sample was unloaded and allowed to return to ambient temperature. The test was repeated to simulate reusability, in order to evaluate its effects on material permeability.

  13. Lunar electrical conductivity and magnetic permeability

    Science.gov (United States)

    Dyal, P.; Parkin, C. W.; Daily, W. D.

    1975-01-01

    Improved analytical techniques are applied to a large Apollo magnetometer data set to yield values of electroconductivity, temperature, magnetic permeability, and iron abundance. Average bulk electroconductivity of the moon is calculated to be .0007 mho/m; a rapid increase with depth to about .003 mho/m within 250 km is indicated. The temperature profile, obtained from the electroconductivity profile for olivine, indicates high lunar temperatures at relatively shallow depths. Magnetic permeability of the moon relative to its environment is calculated to be 1.008 plus or minus .005; a permeability relative to free space of 1.012 plus 0.011, minus 0.008 is obtained. Lunar iron abundances corresponding to this permeability value are 2.5 plus 2.3, minus 1.7 wt% free iron and 5.0-13.5 wt% total iron for a moon composed of a combination of free iron, olivine, and orthopyroxene.

  14. Permeable landscapes for wildlife in the Northeast

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Landscape permeability, also referred to as "habitat connectivity," is the ability of a diverse land area to provide for passage of animals. This project will...

  15. Measuring CO2 and HCO3- permeabilities of isolated chloroplasts using a MIMS-18O approach.

    Science.gov (United States)

    Tolleter, Dimitri; Chochois, Vincent; Poiré, Richard; Price, G Dean; Badger, Murray R

    2017-06-01

    To support photosynthetic CO2 fixation by Rubisco, the chloroplast must be fed with inorganic carbon in the form of CO2 or bicarbonate. However, the mechanisms allowing the rapid passage of this gas and this charged molecule through the bounding membranes of the chloroplast envelope are not yet completely elucidated. We describe here a method allowing us to measure the permeability of these two molecules through the chloroplast envelope using a membrane inlet mass spectrometer and 18O-labelled inorganic carbon. We established that the internal stromal carbonic anhydrase activity is not limiting for this technique, and precisely measured the chloroplast surface area and permeability values for CO2 and bicarbonate. This was performed on chloroplasts from several plant species, with values ranging from 2.3 × 10-4 m s-1 to 8 × 10-4 m s-1 permeability for CO2 and 1 × 10-8 m s-1 for bicarbonate. We were able to apply our method to chloroplasts from an Arabidopsis aquaporin mutant, and this showed that CO2 permeability was reduced 50% in the mutant compared with the wild-type reference. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  16. Food Packaging Permeability Behaviour: A Report

    OpenAIRE

    Valentina Siracusa

    2012-01-01

    The use of polymer materials in food packaging field is one of the largest growing market area. Actually the optimization behaviour of packaging permeability is of crucial importance, in order to extend the food shelf-life and to reach the best engineering solution. Studying the permeability characterization of the different polymer material (homogeneous and heterogeneous polymer system) to the different packaging gases, in different environmental condition, is crucial to understand if the se...

  17. Pneumatic fracturing of low permeability media

    Energy Technology Data Exchange (ETDEWEB)

    Schuring, J.R. [New Jersey Institute of Technology, Newark, NJ (United States)

    1996-08-01

    Pneumatic fracturing of soils to enhance the removal and treatment of dense nonaqueous phase liquids is described. The process involves gas injection at a pressure exceeding the natural stresses and at a flow rate exceeding the permeability of the formation. The paper outlines geologic considerations, advantages and disadvantages, general technology considerations, low permeability media considerations, commercial availability, efficiency, and costs. Five case histories of remediation using pneumatic fracturing are briefly summarized. 11 refs., 2 figs., 1 tab.

  18. Aerosol printed carbon nanotube strain sensor

    Science.gov (United States)

    Thompson, Bradley; Yoon, Hwan-Sik

    2012-04-01

    In recent years, printed electronics have received attention as a method to produce low-cost macro electronics on flexible substrates. In this regard, inkjet and aerosol printing have been the primary printing methods for producing passive electrical components, transistors, and a number of sensors. In this research, a custom aerosol printer was utilized to create a strain sensor capable of measuring static and dynamic strain. The proposed sensor was created by aerosol printing a multiwall carbon nanotube solution onto an aluminum beam covered with an insulating layer. After printing the carbon nanotube-based sensor, the sensor was tested under quasi-static and vibration strain conditions, and the results are presented. The results show that the printed sensor could potentially serve as an effective method for measuring dynamic strain of structural components.

  19. Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation

    DEFF Research Database (Denmark)

    Bourke, Michael F.; Marriott, Philip J; Glud, Ronnie N.

    2017-01-01

    . Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H......Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to prokaryotes such as bacteria and archaea....../hydrogenase pathway of fermentative eukaryotic H2 production, suggesting that pathway as the source of H2 and dissolved inorganic carbon production. Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae...

  20. Genetic Manipulation of Outer Membrane Permeability: Generating Porous Heterogeneous Catalyst Analogs in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Patel, TN; Park, AHA; Bantat, S

    2014-12-01

    The limited permeability of the E. coli outer membrane can significantly hinder whole-cell biocatalyst performance. In this study, the SARS coronavirus small envelope protein (SCVE) was expressed in E. coli cells previously engineered for periplasmic expression of carbonic anhydrase (CA) activity. This maneuver increased small molecule uptake by the cells, resulting in increased apparent CA activity of the biocatalysts. The enhancements in activity were quantified using methods developed for traditional heterogeneous catalysis. The expression of the SCVE protein was found to significantly reduce the Thiele moduli (phi), as well as increase the effectiveness factors (eta), effective diffusivities (D-e), and permeabilities (P) of the biocatalysts. These catalytic improvements translated into superior performance of the biocatalysts for the precipitation of calcium carbonate from solution which is an attractive strategy for long-term sequestration of captured carbon dioxide. Overall, these results demonstrate that synthetic biology approaches can be used to enhance heterogeneous catalysts incorporated into microbial whole-cell scaffolds.

  1. Relations Between Permeability and Structure of Wood

    Institute of Scientific and Technical Information of China (English)

    Bao Fucheng; Zhao Youke; Lü Jianxiong

    2003-01-01

    The permeability and the structure of heartwood and sapwood of the solvent-exchange dried and the air-dried green-wood of Chinese-fir (Cunninghamia lanceolata (Lamb.) Hook.) and masson pine (Pinus massoniana Lamb.) were measured inorder to study the relations between the permeability and the structure. The results showed that the permeability of sapwood of boththe air-dried and the solvent-exchange dried wood was higher than that of heartwood, and the permeability of the solvent-exchangeddried heartwood and sapwood was higher than that of the air-dried. A higher permeability of wood was attributed to, on the one hand,a bigger number of flow path per unit area of the wood perpendicular to the flow direction resulted from a bigger number ofunaspirated pits per unit area and a bigger number of effective pit openings per membrane, and on the other hand, a smaller numberof tracheid in series connection per unit length parallel to flow direction resulted from a longer tracheid length and an effectivetracheid length for permeability.

  2. Permeability of lateritic soil by various methods

    Directory of Open Access Journals (Sweden)

    Tatiana Tavares Rodriguez

    2015-10-01

    Full Text Available Soil Permeability is an important property of soil used to dimension several types of engineering works, and it can be quantified by the permeability rates. Despite of the great use, the type of the re doubts about the best way to determine de permeability rates. The main questions are: (1 the type of the method and (2 the reproducibility of samples in tropical soils. So, the objective of this work is to evaluate the permeability of a lateritic soil by comparing values of permeability coefficient determined for laboratory and in situ testing. For this, it was chosen the lateritic soil of Campo Experimental de Engenharia Geotécncia (CEEG of the Universidade Estadual de Londrina (UEL and four equipments: constant and variable head permeameters, Guelph permeameter and infiltrometer. The results show that all the methods present mean value of permeability coefficient on the order of 10-3 cm/s whit variation coefficient in range of 37% to 92% , except the constant permeameter. The heterogeneous structure of lateritic soil (in macro and micro pores is the probably determinant of the variability observed.

  3. Massive radius-dependent flow slippage in carbon nanotubes

    Science.gov (United States)

    Siria, Alessandro; Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Bocquet, Lydéric

    2016-11-01

    Nanofluidics is the frontier where the continuum picture of fluid mechanics confronts the atomic nature of matter. Recent reports indicate that carbon nanotubes exhibit exceptional water transport properties due to nearly frictionless interfaces and this has stimulated interest in nanotube-based membranes for desalination, nano-filtration, and energy harvesting. However, the fundamental mechanisms of water transport inside nanotubes and at water-carbon interfaces remain controversial, as existing theories fail to provide a satisfying explanation for the limited experimental results. We report a study of water jets emerging from single nanotubes made of carbon and boron-nitride materials. Our experiments reveal extensive and radius-dependent surface slippage in carbon nanotubes (CNT). In stark contrast, boron-nitride nanotubes (BNNT), which are crystallographically similar to CNTs but electronically different, exhibit no slippage. This shows that slippage originates in subtle atomic-scale details of the solid-liquid interface. ERC StG - NanoSOFT.

  4. Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.

    Science.gov (United States)

    Li, Hui; Kayhanian, Masoud; Harvey, John T

    2013-03-30

    Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability.

  5. Integrated electricity and carbon monoxide production

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, J.

    1994-03-23

    In a process for the production of carbon monoxide and electric power in an IGCC with the removal of sulphur compounds, between the outlet of quenched gas from a partial oxidation unit and a fuel inlet to a combined cycle gas turbine there is a permeable membrane unit to separate a non-permeable stream, which is utilised as a source of carbon monoxide, and a permeate stream, which is used as fuel for the gas turbine of the combined cycle unit. (author)

  6. Purification of carbon nanotubes based on oxygen oxidation%基于氧气氧化法的碳纳米管提纯研究

    Institute of Scientific and Technical Information of China (English)

    苏勋文; 姜芳

    2016-01-01

    化学气相沉积法(CVD)是一种制备碳纳米管(CNTs)的有效方法,但是制备出的碳纳米管粗产品中常混有碳纳米颗粒或石墨碎片,利用常规方法很难将碳纳米管从其他形式碳中分离出来.文中利用氧气氧化法进行碳纳米管的提纯实验.实验表明,当750℃加热10 min后,碳纳米管粗产品质量减少,被提纯,碳纳米管的形貌明显优于被提纯前.并且通过这种提纯方法,得到的碳纳米管含量高,提纯后大部分样品是碳纳米管.但在800℃加热15min,提纯后碳纳米管形貌发生变化,碳纳米管形貌发生扭曲,此温度和加热时间对碳纳米管的形貌产生了破坏,不适合碳纳米管的提纯.

  7. Printable Nano-Field Effect Transistors Combined with Carbon Nanotube Based Printable Interconnect Wires for Large-Area Deployable Active Phased-Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Flexible electronic circuits can be easily integrated with large area (>10m aperture), inflatable antennas to provide distributed control and processing...

  8. Application of a new NMR well logging porosity/permeability calibration to the Arbuckle injection zone of the Wellington CO2 demonstration site

    Science.gov (United States)

    Mason, H. E.; Smith, M. M.; Hao, Y.; Carroll, S.

    2016-12-01

    Carbonate reservoirs hold significant potential for carbon capture and storage (CCS) projects. Target formations for carbon dioxide (CO2) storage must have suitable porosity and permeability properties to ensure adequate long term storage. Of these, permeability can be difficult to estimate in carbonate reservoirs due to the orders of magnitude differences in pore sizes, and the complex geometry of existing pore networks or those developed due to reactive CO2 acidified fluids. One of the primary methods for assessing porosity and permeability of reservoirs is down well nuclear magnetic resonance (NMR) logging tools. Our work has been focused on constraining new porosity/permeability relationships in carbonate rocks using micro X-ray computed tomography (µXRCT) to characterize the pore networks to inform on the observed NMR relaxation behavior. This effort has shown that standard NMR methodologies can produce permeability estimates for carbonate rocks that differ by several orders of magnitude from directly measured values. Our new calibrations have rectified these discrepancies by identifying and accounting for the main properties of these rocks that contribute the measured NMR relaxation properties. Properties such as mineralogy, Fe and Mn content, pore geometry, and pore network tortuosity all contribute to the relaxation behavior observed by NMR and are now accomodated in this new calibration procedure. This work has led to new understanding of the properties of these rock types that control the permeability measured by NMR well logging. In this presentation, we apply the results of a lab measured calibration of porosity and permeability to a high resolution NMR well log produced for the Arbucke injection zone of the Wellington CO2 demonstration sites. This application illustrates the applicability of this new calibration method for carbonate reservoirs and helps advance our understanding of the permeability and porosity relationships in these complex rock

  9. Modeling of external electric field effect on the carbon and silicon carbide nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sorokina, Veronika, E-mail: ansonika@mail.ru [Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034 (Russian Federation); Nikiforov, Konstantin, E-mail: knikiforov@cc.spbu.ru [Saint Petersburg Electrotechnical University “LETI”, 5 Prof. Popova, St. Petersburg, 197376 (Russian Federation)

    2016-06-17

    Studying emission characteristics of nanotubes is extremely important for development of electronics. Compared to other electron sources nanotube-based field emitters allow obtaining significant emission currents at relatively low values of the applied field. It is possible due to their unique structure. This article is devoted to theoretical investigation how external electric field effects several samples of open single-wall nanotubes from carbon and silicon carbide. Total energies, dipole moments and band gaps for five types of nanotubes were calculated from the first principles. The numerical experiment results indicate the adequacy of modeling. It was concluded that considered configurations of achiral carbon nanotubes should be semiconductors.

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

    KAUST Repository

    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.

  11. Relative permeability in dual porosity porous media

    Energy Technology Data Exchange (ETDEWEB)

    Deghmoum, A. [SONATRACH CRD, Boumerdes (Algeria); Tiab, D. [Oklahoma Univ., Norman, OK (United States); Mazouzi, A. [SONATRACH PED (Algeria)

    2000-06-01

    One of the important factors in the field of reservoir simulation of dual-porosity systems is reliable relative permeability data. Laboratory limitations hinder measurements. The real behaviour of naturally fractures reservoirs is not reflected in the reservoir core samples, which as a rule originate from zones without induced or natural fractures. Therefore, it is commonly assumed that the relative permeability of a naturally fractured system is a straight line, which can cause errors. The authors undertook to conduct special core analyses on Berea outcrop core samples, to simulate fracture opening through the cutting of the samples to get different fracture apertures, to study the effects of dual porosity on the shape of capillary pressure curves, and to evaluate absolute and relative permeability, as they are affected by fracture opening. The correlation obtained between absolute permeability and fracture aperture was good, and capillary pressure curves permitted the observation of the effect of dual porosity. High residual oil saturation was present in the matrix, since the fractures became the easiest route for water flow, and this situation prevented the use of unsteady-state tests to measure relative permeability on the samples. Instead, the centrifuge technique was successfully used. A naturally fractured reservoir (NFR), the Tin Fouye Tabankort (TFT) reservoir in Algeria was selected to extend the findings. The site was principally selected due to the availability of naturally fractured cores and published data. Core observations, well test analysis and borehole imager tools were all TFT natural fracture indicators presented in the paper. Representative data of relative permeability was obtained by conducting a displacement test on a full diameter core to solve the laboratory limitations. The correlation between permeability and fracture opening was used to estimate the aperture of natural fractures in TFT reservoir. 17 refs., 2 tabs., 24 figs.

  12. Novel RpoS-Dependent Mechanisms Strengthen the Envelope Permeability Barrier during Stationary Phase.

    Science.gov (United States)

    Mitchell, Angela M; Wang, Wei; Silhavy, Thomas J

    2017-01-15

    Gram-negative bacteria have effective methods of excluding toxic compounds, including a largely impermeable outer membrane (OM) and a range of efflux pumps. Furthermore, when cells become nutrient limited, RpoS enacts a global expression change providing cross-protection against many stresses. Here, we utilized sensitivity to an anionic detergent (sodium dodecyl sulfate [SDS]) to probe changes occurring to the cell's permeability barrier during nutrient limitation. Escherichia coli is resistant to SDS whether cells are actively growing, carbon limited, or nitrogen limited. In actively growing cells, this resistance depends on the AcrAB-TolC efflux pump; however, this pump is not necessary for protection under either carbon-limiting or nitrogen-limiting conditions, suggesting an alternative mechanism(s) of SDS resistance. In carbon-limited cells, RpoS-dependent pathways lessen the permeability of the OM, preventing the necessity for efflux. In nitrogen-limited but not carbon-limited cells, the loss of rpoS can be completely compensated for by the AcrAB-TolC efflux pump. We suggest that this difference simply reflects the fact that nitrogen-limited cells have access to a metabolizable energy (carbon) source that can efficiently power the efflux pump. Using a transposon mutant pool sequencing (Tn-Seq) approach, we identified three genes, sanA, dacA, and yhdP, that are necessary for RpoS-dependent SDS resistance in carbon-limited stationary phase. Using genetic analysis, we determined that these genes are involved in two different envelope-strengthening pathways. These genes have not previously been implicated in stationary-phase stress responses. A third novel RpoS-dependent pathway appears to strengthen the cell's permeability barrier in nitrogen-limited cells. Thus, though cells remain phenotypically SDS resistant, SDS resistance mechanisms differ significantly between growth states. Gram-negative bacteria are intrinsically resistant to detergents and many

  13. Plasticity and Kinky Chemistry of Carbon Nanotubes

    Science.gov (United States)

    Srivastava, Deepak; Dzegilenko, Fedor

    2000-01-01

    Since their discovery in 1991, carbon nanotubes have been the subject of intense research interest based on early predictions of their unique mechanical, electronic, and chemical properties. Materials with the predicted unique properties of carbon nanotubes are of great interest for use in future generations of aerospace vehicles. For their structural properties, carbon nanotubes could be used as reinforcing fibers in ultralight multifunctional composites. For their electronic properties, carbon nanotubes offer the potential of very high-speed, low-power computing elements, high-density data storage, and unique sensors. In a continuing effort to model and predict the properties of carbon nanotubes, Ames accomplished three significant results during FY99. First, accurate values of the nanomechanics and plasticity of carbon nanotubes based on quantum molecular dynamics simulations were computed. Second, the concept of mechanical deformation catalyzed-kinky-chemistry as a means to control local chemistry of nanotubes was discovered. Third, the ease of nano-indentation of silicon surfaces with carbon nanotubes was established. The elastic response and plastic failure mechanisms of single-wall nanotubes were investigated by means of quantum molecular dynamics simulations.

  14. In vivo human buccal permeability of nicotine

    DEFF Research Database (Denmark)

    Adrian, Charlotte L; Olin, Helle B D; Dalhoff, Kim

    2006-01-01

    The aim was to examine the in vivo buccal pH-dependent permeability of nicotine in humans and furthermore compare the in vivo permeability of nicotine to previous in vitro permeability data. The buccal permeability of nicotine was examined in a three-way cross-over study in eight healthy non......-smokers using a buccal perfusion cell. The disappearance of nicotine from perfusion solutions with pH 6.0, 7.4, and 8.1 was studied for 3h. The apparent permeability of nicotine (P(app)) was determined at each pH value. Parotid saliva was collected in an attempt to assess systemic levels of nicotine....... The disappearance rate of nicotine increased significantly as the pH increased, which resulted in P(app) values of 0.57+/-0.55 x 10(-4), 2.10+/-0.23 x 10(-4), and 3.96+/-0.54 x 10(-4)cms(-1) (mean+/-S.D.) at pH 6.0, 7.4, and 8.1, respectively. A linear relationship (R(2)=0.993) was obtained between the P...

  15. Permeability Tests on Silkeborg Sand No. 0000

    DEFF Research Database (Denmark)

    Lund, Willy; Jakobsen, Kim Parsberg

    The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends on the charact......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...... on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Silkeborg Sand No. 0000. The permeability is determined by use of a falling head apparatus. The apparatus, test procedures and the analysis method are described...... in the succeeding sections. Finally the test results are briefly summarised and a relationship between void ratio l and permeability is established....

  16. Vascular permeability in cerebral cavernous malformations

    DEFF Research Database (Denmark)

    Mikati, Abdul G; Khanna, Omaditya; Zhang, Lingjiao;

    2015-01-01

    Patients with the familial form of cerebral cavernous malformations (CCMs) are haploinsufficient for the CCM1, CCM2, or CCM3 gene. Loss of corresponding CCM proteins increases RhoA kinase-mediated endothelial permeability in vitro, and in mouse brains in vivo. A prospective case-controlled observ......Patients with the familial form of cerebral cavernous malformations (CCMs) are haploinsufficient for the CCM1, CCM2, or CCM3 gene. Loss of corresponding CCM proteins increases RhoA kinase-mediated endothelial permeability in vitro, and in mouse brains in vivo. A prospective case......-controlled observational study investigated whether the brains of human subjects with familial CCM show vascular hyperpermeability by dynamic contrast-enhanced quantitative perfusion magnetic resonance imaging, in comparison with CCM cases without familial disease, and whether lesional or brain vascular permeability...... correlates with CCM disease activity. Permeability in white matter far (WMF) from lesions was significantly greater in familial than in sporadic cases, but was similar in CCM lesions. Permeability in WMF increased with age in sporadic patients, but not in familial cases. Patients with more aggressive...

  17. Honeycomb Core Permeability Under Mechanical Loads

    Science.gov (United States)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  18. Metabolism in anoxic permeable sediments is dominated by eukaryotic dark fermentation

    Science.gov (United States)

    Bourke, Michael F.; Marriott, Philip J.; Glud, Ronnie N.; Hasler-Sheetal, Harald; Kamalanathan, Manoj; Beardall, John; Greening, Chris; Cook, Perran L. M.

    2017-01-01

    Permeable sediments are common across continental shelves and are critical contributors to marine biogeochemical cycling. Organic matter in permeable sediments is dominated by microalgae, which as eukaryotes have different anaerobic metabolic pathways to bacteria and archaea. Here we present analyses of flow-through reactor experiments showing that dissolved inorganic carbon is produced predominantly as a result of anaerobic eukaryotic metabolic activity. In our experiments, anaerobic production of dissolved inorganic carbon was consistently accompanied by large dissolved H2 production rates, suggesting the presence of fermentation. The production of both dissolved inorganic carbon and H2 persisted following administration of broad spectrum bactericidal antibiotics, but ceased following treatment with metronidazole. Metronidazole inhibits the ferredoxin/hydrogenase pathway of fermentative eukaryotic H2 production, suggesting that pathway as the source of H2 and dissolved inorganic carbon production. Metabolomic analysis showed large increases in lipid production at the onset of anoxia, consistent with documented pathways of anoxic dark fermentation in microalgae. Cell counts revealed a predominance of microalgae in the sediments. H2 production was observed in dark anoxic cultures of diatoms (Fragilariopsis sp.) and a chlorophyte (Pyramimonas) isolated from the study site, substantiating the hypothesis that microalgae undertake fermentation. We conclude that microalgal dark fermentation could be an important energy-conserving pathway in permeable sediments.

  19. Enhancement of interfacial thermal transport by carbon nanotube-graphene junction

    Science.gov (United States)

    Bao, Hua; Shao, Cheng; Luo, Shirui; Hu, Ming

    2014-02-01

    Due to the high intrinsic thermal conductivity, carbon nanotubes are very promising to serve as effective thermal interface materials for microelectronics or other cooling applications. However, the performance of carbon nanotube based thermal interface material is strongly limited by the small effective contact area and weak bonding at carbon nanotube and material interface. Here, we propose a junction structure that the carbon nanotube is bonded with a monolayer graphene, which could potentially enhance the interface thermal conductance. Molecular dynamics simulations show that the interface thermal conductance can be enhanced by at least 40% compared to direct carbon nanotube and silicon interface with strong covalent bonding, while for weak van der Waals bonding the conductance can be enhanced by almost one order of magnitude. The enhancement of thermal conductance is attributed to the efficient thermal transport between carbon nanotube and graphene, as well as the good contact between graphene and silicon surface.

  20. Integration of UV-cured Ionogel Electrolyte with Carbon Paper Electrodes

    Directory of Open Access Journals (Sweden)

    Stephanie Flores Zopf

    2014-02-01

    Full Text Available A test bed with a coplanar architecture is employed to investigate the integration of an in situ cross-linked, polymer-supported ionogel with several commercially available, high surface area carbon paper electrodes. Specifically, a UV-cured poly(ethylene glycol diacrylate (PEGDA-supported ionogel electrolyte film is formed in situ against a variety of porous electrodes comprising: a carbon fiber paper, a carbon aerogel paper, and four carbon nanotube-based papers. Electrochemical impedance spectroscopy measurements reveal that the relative performance of a particular carbon paper with the neat ionic liquid is not necessarily indicative of its behavior when integrated with the solid ionogel electrolyte. The coplanar test bed can therefore serve as a useful tool to help guide the selection of suitable carbon-based electrode structures for supercapacitors that incorporate UV-cured ionogels created in situ for wearable energy storage applications.

  1. Effects of Permeability Variations on CO2 Convection in Anisotropic and Heterogeneous Saline Formations

    Directory of Open Access Journals (Sweden)

    Chi-Ping Lin

    2016-02-01

    Full Text Available This study simulated the natural convection of dissolved carbon dioxide (CO2 in a small-scale heterogeneous saline formation using the state module ECO2N equation in the TOUGHREACT model. A one-way downscaling approach that involves using a series of sub-models in simulation procedures was proposed to efficiently simulate problems with high-scale discrepancies. This study evaluated the effects of different degrees of small-scale permeability variations on the vertical migration of dissolved CO2. The sequential Gaussian simulation model was used to generate unconditional random permeability fields for different natural logarithm of permeability (lnk variations (i.e., lnk variances and correlations in x and z directions. The results showed an identical transition zone of dissolved CO2 near the top boundary, where a constant CO2 gas saturation was specified. The local permeability variations can trigger fingerings and enhance the vertical convection of the dissolved CO2. The number of fingerings depends on the variations in permeability near the front interface of the dissolved CO2 (i.e., the bottom edge of the transition zone for the dissolved CO2. However, the fingering patterns and developments are constrained by the permeability variations along the fingering paths. At the same mean lnk permeability the convection fluxes increase with an increase in lnk variances. However, an increase in lateral correlations (i.e., increase in the correlation lengths in the x direction can slightly reduce the convection fluxes at the same lnk variance. The highly variable flux rates of the dissolved CO2 occur early and the variations in the flux rate decrease with time.

  2. Effect of stress sensitivity on displacement efficiency in CO2 flooding for fractured low permeability reservoirs

    Institute of Scientific and Technical Information of China (English)

    Wang Rui; Yue Xiangan; Zhao Renbao; Yan Pingxiang; Dave Freeman

    2009-01-01

    Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.

  3. Durable Suit Bladder with Improved Water Permeability for Pressure and Environment Suits

    Science.gov (United States)

    Bue, Grant C.; Kuznetz, Larry; Orndoff, Evelyne; Tang, Henry; Aitchison, Lindsay; Ross, Amy

    2009-01-01

    Water vapor permeability is shown to be useful in rejecting heat and managing moisture accumulation in launch-and-entry pressure suits. Currently this is accomplished through a porous Gortex layer in the Advanced Crew and Escape Suit (ACES) and in the baseline design of the Constellation Suit System Element (CSSE) Suit 1. Non-porous dense monolithic membranes (DMM) that are available offer potential improvements for water vapor permeability with reduced gas leak. Accordingly, three different pressure bladder materials were investigated for water vapor permeability and oxygen leak: ElasthaneTM 80A (thermoplastic polyether urethane) provided from stock polymer material and two custom thermoplastic polyether urethanes. Water vapor, carbon dioxide and oxygen permeability of the DMM's was measured in a 0.13 mm thick stand-alone layer, a 0.08 mm and 0.05 mm thick layer each bonded to two different nylon and polyester woven reinforcing materials. Additional water vapor permeability and mechanical compression measurements were made with the reinforced 0.05 mm thick layers, further bonded with a polyester wicking and overlaid with moistened polyester fleece thermal underwear .This simulated the pressure from a supine crew person. The 0.05 mm thick nylon reinforced sample with polyester wicking layer was further mechanically tested for wear and abrasion. Concepts for incorporating these materials in launch/entry and Extravehicular Activity pressure suits are presented.

  4. Tunable permeability of magnetic wires at microwaves

    Science.gov (United States)

    Panina, L. V.; Makhnovskiy, D. P.; Morchenko, A. T.; Kostishin, V. G.

    2015-06-01

    This paper presents the analysis into microwave magnetic properties of magnetic microwires and their composites in the context of applications in wireless sensors and tunable microwave materials. It is demonstrated that the intrinsic permeability of wires has a wide frequency dispersion with relatively large values in the GHz band. In the case of a specific magnetic anisotropy this results in a tunable microwave impedance which could be used for distributed wireless sensing networks in functional composites. The other range of applications is related with developing the artificial magnetic dielectrics with large and tunable permeability. The composites with magnetic wires with a circumferential anisotropy have the effective permeability which differs substantially from unity for a relatively low concentration (less than 10%). This can make it possible to design the wire media with a negative and tunable index of refraction utilising natural magnetic properties of wires.

  5. Gyroid Nanoporous Membranes with Tunable Permeability

    DEFF Research Database (Denmark)

    Li, Li; Schulte, Lars; Clausen, Lydia D.

    2011-01-01

    Understanding the relevant permeability properties of ultrafiltration membranes is facilitated by using materials and procedures that allow a high degree of control on morphology and chemical composition. Here we present the first study on diffusion permeability through gyroid nanoporous cross......-sided skin membranes, much faster than expected by a naive resistance-in-series model; the flux through the two-sided skin membranes even increases with the membrane thickness. We propose a model that captures the physics behind the observed phenomena, as confirmed by flow visualization experiments...... the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive...

  6. Ammonia and urea permeability of mammalian aquaporins

    DEFF Research Database (Denmark)

    Litman, Thomas; Søgaard, Rikke; Zeuthen, Thomas

    2009-01-01

    The human aquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3, are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea transporters (UTs). The mechanism by which...... ammonium is transported by aquaporins is not fully resolved. A comparison of transport equations, models, and experimental data shows that ammonia is transported in its neutral form, NH(3). In the presence of NH(3), the aquaporin stimulates H(+) transport. Consequently, this transport of H(+) is only...... significant at alkaline pH. It is debated whether the H(+) ion passes via the aquaporin or by some external route; the investigation of this problem requires the aquaporin-expressing cell to be voltage-clamped. The ammonia-permeable aquaporins differ from other aquaporins by having a less restrictive aromatic...

  7. Permeability of Hollow Microspherical Membranes to Helium

    Science.gov (United States)

    Zinoviev, V. N.; Kazanin, I. V.; Pak, A. Yu.; Vereshchagin, A. S.; Lebiga, V. A.; Fomin, V. M.

    2016-01-01

    This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption-desorption dependences of the studied sorbents have been obtained, from which the parameters of their specific permeability to helium are calculated. It has been established that the physicochemical modification of the original particles exerts a great influence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.

  8. Food Packaging Permeability Behaviour: A Report

    Directory of Open Access Journals (Sweden)

    Valentina Siracusa

    2012-01-01

    Full Text Available The use of polymer materials in food packaging field is one of the largest growing market area. Actually the optimization behaviour of packaging permeability is of crucial importance, in order to extend the food shelf-life and to reach the best engineering solution. Studying the permeability characterization of the different polymer material (homogeneous and heterogeneous polymer system to the different packaging gases, in different environmental condition, is crucial to understand if the selected material is adapted to the chosen food contact field. Temperature and humidity parameters are of crucial importance for food quality preservation, especially in real life situations, like food market, and house long-life use. The aim of this report was to collect information about the state of the art on the permeability characteristics of the polymer packages used on food field.

  9. Magnetohydrodynamic Flow Past a Permeable Bed

    Directory of Open Access Journals (Sweden)

    R. Venugopal

    1983-01-01

    Full Text Available The paper evaluates mass flow velocity heat transfer rates and velocity/temperature distributions in the viscous, incompressible and slightly conducting fluid past a permeable bed in three different configurations namely (1 Couette flow (2 Poiseuille flow and (3 free surface flow, under the influence of a uniform transverse magnetic field. To discuss the solution, the flow region is divided into two zones : Zone 1 (from the impermeable upper rigid plate to the permeable bed in which the flow is laminar and governed by Navier-Stokes equations, and Zone 2 (the permeable bed below the nominal surface in which the flow is governed by Darcy law. The paper also investigates the effects of magnetic field, porosity and Biot number on the physical quantities mentioned above.

  10. Quantifying porosity, compressibility and permeability in Shale

    DEFF Research Database (Denmark)

    Mbia, Ernest Ncha; Fabricius, Ida Lykke; Frykman, Peter

    (XRD) of shale samples show about 50% silt and high content of kaolinite in the clay fraction when compared with offshore samples from the Central Graben. Porosity measurements from helium porosimetry-mercury immersion (HPMI), mercury injection capillary pressure (MICP) and nuclear magnetic resonance...... (NMR) show that, the MICP porosity is 9-10% points lower than HPMI and NMR porosity. Compressibility result shows that deep shale is stiffer in situ than normally assumed in geotechnical modelling and that static compressibility corresponds with dynamic one only at the begining of unloading stress...... strain data. We found that Kozeny's modelled permeability fall in the same order of magnitude with measured permeability for shale rich in kaolinite but overestimates permeability by two to three orders of magnitudes for shale with high content of smectite. The empirical Yang and Aplin model gives good...

  11. Magnetic levitation from negative permeability materials

    Energy Technology Data Exchange (ETDEWEB)

    Coffey, Mark W., E-mail: mcoffey@mines.edu [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States)

    2012-09-03

    As left-handed materials and metamaterials are becoming more prevalent, we examine the effect of negative permeability upon levitation force. We first consider two half spaces of differing permeability and a point magnetic source, so that the method of images may be employed. We determine that the resulting force may be larger than for conventional magnetic materials. We then illustrate the inclusion of a finite sample thickness. -- Highlights: ► The effect of negative permeability upon levitation force is considered. ► Such an effect could be realized with metamaterials. ► The resulting force may be larger than with conventional materials. ► The analysis is extended to allow for a finite sample thickness. ► Representative numerical values are given.

  12. Blood flow and permeability in microvessels

    Science.gov (United States)

    Sugihara-Seki, Masako; Fu, Bingmei M.

    2005-07-01

    The mechanics of blood flow in microvessels and microvessel permeability are reviewed. In the first part, characteristics of blood flow in vivo and in vitro are described from a fluid-mechanical point of view, and mathematical models for blood flow in microvessels are presented. Possible causes of the increased flow resistance obtained in vivo compared to in vitro are examined, including the effects of irregularities of vessel lumen, the presence of endothelial surface glycocalyx and white blood cells. In the second part, the ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate microvessel permeability to water and solutes are introduced. Previous and current models for microvessel permeability to water and solutes are reviewed. These models examine the role of structural components of interendothelial cleft, such as junction strands and surface glycocalyx, in the determination of water and solute transport across the microvessel walls. Transport models in the tissue space surrounding the microvessel are also described.

  13. High-Throughput Processes and Structural Characterization of Single-Nanotube Based Devices for 3D Electronics

    Science.gov (United States)

    Kaul, A. B.; Megerian, K. G.; Baron, R. L.; Jennings, A. T.; Jang, D.; Greer, J. R.

    2011-01-01

    We have developed manufacturable approaches to form single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 micron deep trenches. These wafer-scale approaches were enabled by chemically amplified resists and inductively coupled Cryo-etchers to form the 3D nanoscale architectures. The tube growth was performed using dc plasmaenhanced chemical vapor deposition (PECVD), and the materials used for the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. The TEM analysis of our tubes revealed graphitic basal planes inclined to the central or fiber axis, with cone angles up to 30 deg. for the particular growth conditions used. In addition, bending tests performed using a custom nanoindentor, suggest that the tubes are well adhered to the Si substrate. Tube characteristics were also engineered to some extent, by adjusting growth parameters, such as Ni catalyst thickness, pressure and plasma power during growth.

  14. Small-bowel permeability in collagenous colitis

    DEFF Research Database (Denmark)

    Wildt, Signe; Madsen, Jan L; Rumessen, Jüri J

    2006-01-01

    Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small-intestinal biopsies......, indicating that CC is a pan-intestinal disease. In small-intestinal disease, the intestinal barrier function may be impaired, and the permeability of the small intestine altered. The purpose of this research was to study small-bowel function in patients with CC as expressed by intestinal permeability....

  15. Liquid Permeability of Ceramic Foam Filters

    OpenAIRE

    Zhang, Kexu

    2012-01-01

    This project is in support of the PhD project: ‘Removal of Inclusions from Liquid Aluminium using Electromagnetically Modified Filtration’. The purpose of this project was to measure the tortuosity, and permeability of ~50mm thick: 30, 40, 50 and 80 pores per inch (ppi) commercial alumina ceramic foam filters (CFFs). Measurements have been taken of: cell (pore), window and strut sizes, porosity, tortuosity and liquid permeability. Water velocity from ~0.015-0.77 m/s have been used ...

  16. Development of an Improved Permeability Modification Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Gao, H.W.; Elphnick, J.

    1999-03-09

    This report describes the development of an improved permeability modification simulator performed jointly by BDM Petroleum Technologies and Schlumberger Dowell under a cooperative research and development agreement (CRADA) with the US Department of Energy. The improved simulator was developed by modifying NIPER's PC-GEL permeability modification simulator to include a radial model, a thermal energy equation, a wellbore simulator, and a fully implicit time-stepping option. The temperature-dependent gelation kinetics of a delayed gel system (DGS) is also included in the simulator.

  17. The Permeability of Rubble Mound Breakwaters

    DEFF Research Database (Denmark)

    Williams, A.F.; Burcharth, H. F.; Adel, H. den

    1992-01-01

    The results of an extensive series of permeability experiments originally analysed by Shih (1990) are reinterpreted in the light of new experiments. It is proposed that the Forchheimer equation might not fully describe flow at the high Reynolds numbers found in the interior of rubble material....... A new series of tests designed to test for deviations from the Forchheimer equation and investigate the effects of material shape are described. While no evidence can be found to indicate a deviation from the Forchheimer equation a dependency of permeability and the surface roughness the material...

  18. Effect of the aggregate grading on the concrete air permeability

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2014-09-01

    Full Text Available Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on. Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a Dair increase of 40–80%.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.. El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad. Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del Dair

  19. Rhubarb Antagonizes Matrix Metalloproteinase-9-induced Vascular Endothelial Permeability

    Institute of Scientific and Technical Information of China (English)

    Yun-Liang Cui; Sheng Zhang; Zhao-Tao Tian; Zhao-Fen Lin; De-Chang Chen

    2016-01-01

    Background:Intact endothelial structure and function are critical for maintaining microcirculatory homeostasis.Dysfunction of the latter is an underlying cause of various organ pathologies.In a previous study,we showed that rhubarb,a traditional Chinese medicine,protected intestinal mucosal microvascular endothelial cells in rats with metastasizing septicemia.In this study,we investigated the effects and mechanisms of rhubarb on matrix metalloproteinase-9 (MMP9)-induced vascular endothelial (VE) permeability.Methods:Rhubarb monomers were extracted and purified by a series of chromatography approaches.The identity of these monomers was analyzed by hydrogen-1 nuclear magnetic resonance (NMR),carbon-13 NMR,and distortionless enhancement by polarization transfer magnetic resonance spectroscopy.We established a human umbilical vein endothelial cell (HUVEC) monolayer on a Transwell insert.We measured the HUVEC permeability,proliferation,and the secretion of VE-cadherin into culture medium using fluorescein isothiocyanate-dextran assay,3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay,and enzyme-linked immunosorbent assay,respectively,in response to treatment with MMP9 and/or rhubarb monomers.Results:A total of 21 rhubarb monomers were extracted and identified.MMP9 significantly increased the permeability of the HUVEC monolayer,which was significantly reduced by five individual rhubarb monomer (emodin,3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid,1-O-caffeoyl-2-(4-hydroxyl-O-cinnamoyl)-β-D-glucose,daucosterol linoleate,and rhein) or a combination of all five monomers (1 μmol/L for each monomer).Mechanistically,the five-monomer mixture at 1 μmol/L promoted HUVEC proliferation.In addition,MMP9 stimulated the secretion of VE-cadherin into the culture medium,which was significantly inhibited by the five-monomer mixture.Conclusions:The rhubarb mixture of emodin,3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid,1-O-caffeoyl-2-(4-hydroxyl

  20. Rotation-excited perfect oscillation of a tri-walled nanotube-based oscillator at ultralow temperature

    Science.gov (United States)

    Cai, Kun; Zhang, Xiaoni; Shi, Jiao; Qin, Qing H.

    2017-04-01

    In recent years, carbon-nanotube (CNT)-based gigahertz oscillators have been widely used in numerous areas of practical engineering such as high-speed digital, analog circuits, and memory cells. One of the major challenges to practical applications of the gigahertz oscillator is generating a stable oscillation process from the gigahertz oscillators and then maintaining the stable process for a specified period of time. To address this challenge, an oscillator from a triple-walled CNT-based rotary system is proposed and analyzed numerically in this paper, using a molecular dynamics approach. In this system, the outer tube is fixed partly as a stator. The middle tube, with a constant rotation, is named Rotor 2 and runs in the stator. The inner tube acts as Rotor 1, which can rotate freely in Rotor 2. Due to the friction between the two rotors when they have relative motion, the rotational frequency of Rotor 1 increases continuously and tends to converge with that of Rotor 2. During rotation, the oscillation of Rotor 1 may be excited owing to both a strong end barrier at Rotor 2 and thermal vibration of atoms in the tubes. From the discussion on the effects of length of Rotor 1, temperature, and input rotational frequency of Rotor 2 on the dynamic response of Rotor 1, an effective way to control the oscillation of Rotor 1 is found. Being much longer than Rotor 2, Rotor 1 will have perfect oscillation, i.e., with both stable (or nearly constant) period and amplitude—especially at relatively low temperature. This discovery can be taken as a useful guidance for the design of an oscillator from CNTs.