Estimation of mechanical properties of single wall carbon nanotubes ...

Indian Academy of Sciences (India)

Molecular mechanics; single wall carbon nanotube; mechanical proper- ... Fracture Mechanics); Rossi & Meo 2009). Furthermore, the work carried out by Natsuki & Endo. (2004), Xiao et al (2005) and Sun & Zhao (2005) in the direction of ..... Jin Y and Yuan F G 2003 Simulation of elastic properties of single walled carbon ...

Stable single helical C- and I-chains inside single-walled carbon nanotubes

International Nuclear Information System (INIS)

Yao Z; Li Y; Jing X D; Meng F S; Zhao X; Li J H; Qiu Z Y; Yuan Q; Wang W X; Bi L; Liu H; Zhang Y P; Liu C J; Zheng S P; Liu B B

2016-01-01

The helicity of stable single helical carbon chains and iodine chains inside single-walled carbon nanotubes (SWCNTs) is studied by calculating the systematic van der Waals interaction energy. The results show that the optimal helical radius increases linearly with increasing tube radius, which produces a constant separation between the chain structure and the tube wall. The helical angle exhibits a ladder-like decrease with increasing tube radius, indicating that a large tube can produce a small helicity in the helical structures. (paper)

Single Nucleotide Polymorphism Detection Using Au-Decorated Single-Walled Carbon Nanotube Field Effect Transistors

Directory of Open Access Journals (Sweden)

Keum-Ju Lee

2011-01-01

Full Text Available We demonstrate that Au-cluster-decorated single-walled carbon nanotubes (SWNTs may be used to discriminate single nucleotide polymorphism (SNP. Nanoscale Au clusters were formed on the side walls of carbon nanotubes in a transistor geometry using electrochemical deposition. The effect of Au cluster decoration appeared as hole doping when electrical transport characteristics were examined. Thiolated single-stranded probe peptide nucleic acid (PNA was successfully immobilized on Au clusters decorating single-walled carbon nanotube field-effect transistors (SWNT-FETs, resulting in a conductance decrease that could be explained by a decrease in Au work function upon adsorption of thiolated PNA. Although a target single-stranded DNA (ssDNA with a single mismatch did not cause any change in electrical conductance, a clear decrease in conductance was observed with matched ssDNA, thereby showing the possibility of SNP (single nucleotide polymorphism detection using Au-cluster-decorated SWNT-FETs. However, a power to discriminate SNP target is lost in high ionic environment. We can conclude that observed SNP discrimination in low ionic environment is due to the hampered binding of SNP target on nanoscale surfaces in low ionic conditions.

500 MW demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide emissions from coal-fired boilers

Energy Technology Data Exchange (ETDEWEB)

Sorge, J.N.; Larrimore, C.L.; Slatsky, M.D.; Menzies, W.R.; Smouse, S.M.; Stallings, J.W.

1997-12-31

This paper discusses the technical progress of a US Department of Energy Innovative Clean Coal Technology project demonstrating advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NOx) emissions from coal-fired boilers. The primary objectives of the demonstration is to determine the long-term NOx reduction performance of advanced overfire air (AOFA), low NOx burners (LNB), and advanced digital control optimization methodologies applied in a stepwise fashion to a 500 MW boiler. The focus of this paper is to report (1) on the installation of three on-line carbon-in-ash monitors and (2) the design and results to date from the advanced digital control/optimization phase of the project.

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. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on the Microwave Permittivity of Single-Walled Carbon Nanotube

Science.gov (United States)

Liu, Xiaolai; Zhao, Donglin

2009-01-01

In this article, we studied the microwave permittivity of the complex of the single-walled carbon nanotube and paraffin in 2-18GHz. In the range, the dielectric loss of single-walled carbon nanotube is higher, and the real part and the imaginary part of the dielectric constant decrease with the increase of frequency, and the dielectric constant…

Monte-Carlo Simulation of Hydrogen Adsorption in Single-Wall Carbon Nano-Cones

Directory of Open Access Journals (Sweden)

Zohreh Ahadi

2011-01-01

Full Text Available The properties of hydrogen adsorption in single-walled carbon nano-cones are investigated in detail by Monte Carlo simulations. A great deal of our computational results show that the hydrogen storage capacity in single-walled carbon nano-cones is slightly smaller than the capacity of single-walled carbon nanotubes at any time at the same conditions. This indicates that the hydrogen storage capacity of single-walled carbon nano-cones is related to angles of carbon nano-cones. It seems that these type of nanotubes could not exceed the 2010 goal of 6 wt%, which is presented by the U.S. Department of Energy. In addition, these results are discussed in theory.

Magnetic domain wall conduits for single cell applications

DEFF Research Database (Denmark)

Donolato, Marco; Torti, A.; Kostesha, Natalie

2011-01-01

The ability to trap, manipulate and release single cells on a surface is important both for fundamental studies of cellular processes and for the development of novel lab-on-chip miniaturized tools for biological and medical applications. In this paper we demonstrate how magnetic domain walls...... walls over 16 hours. Moreover, we demonstrate the controlled transport and release of individual yeast cells via displacement and annihilation of individual domain walls in micro- and nano-sized magnetic structures. These results pave the way to the implementation of magnetic devices based on domain...... walls technology in lab-on-chip systems devoted to accurate individual cell trapping and manipulation....

Domain walls in single-chain magnets

Science.gov (United States)

Pianet, Vivien; Urdampilleta, Matias; Colin, Thierry; Clérac, Rodolphe; Coulon, Claude

2017-12-01

The topology and creation energy of domain walls in different magnetic chains (called Single-Chain Magnets or SCMs) are discussed. As these domain walls, that can be seen as "defects", are known to control both static and dynamic properties of these one-dimensional systems, their study and understanding are necessary first steps before a deeper discussion of the SCM properties at finite temperature. The starting point of the paper is the simple regular ferromagnetic chain for which the characteristics of the domain walls are well known. Then two cases will be discussed (i) the "mixed chains" in which isotropic and anisotropic classical spins alternate, and (ii) the so-called "canted chains" where two different easy axis directions are present. In particular, we show that "strictly narrow" domain walls no longer exist in these more complex cases, while a cascade of phase transitions is found for canted chains as the canting angle approaches 45∘. The consequence for thermodynamic properties is briefly discussed in the last part of the paper.

Bloch walls in a nickel single crystal

International Nuclear Information System (INIS)

Peters, J.; Treimer, W.

2001-01-01

We present a consistent theory for the dependence of the magnetic structure in bulk samples on external static magnetic fields and corresponding experimental results. We applied the theory of micromagnetism to this crystal and calculated the Bloch wall thickness as a function of external magnetic fields. The theoretical results agree well with the experimental data, so that the Bloch wall thickness of a 71 deg. nickel single crystal was definitely determined with some hundred of nanometer

Bird communities following high-severity fire: Response to single and repeat fires in a mixed-evergreen forest, Oregon, USA

Science.gov (United States)

Joseph B. Fontaine; Daniel C. Donato; W. Douglas Robinson; Beverly E. Law; J. Boone Kauffman

2009-01-01

Fire is a widespread natural disturbance agent in most conifer-dominated forests. In light of climate change and the effects of fire exclusion, single and repeated high-severity (stand-replacement) fires have become prominent land management issues. We studied bird communities using point counting in the Klamath-Siskiyou ecoregion of Oregon, USA at various points in...

Collapse and stability of single- and multi-wall carbon nanotubes

International Nuclear Information System (INIS)

Xiao, J; Liu, B; Huang, Y; Zuo, J; Hwang, K-C; Yu, M-F

2007-01-01

The collapse and stability of carbon nanotubes (CNTs) have important implications for their synthesis and applications. While nanotube collapse has been observed experimentally, the conditions for the collapse, especially its dependence on tube structures, are not clear. We have studied the energetics of the collapse of single- and multi-wall CNTs via atomistic simulations. The collapse is governed by the number of walls and the radius of the inner-most wall. The collapsed structure is energetically favored about a certain diameter, which is 4.12, 4.96 and 5.76 nm for single-, double- and triple-wall CNTs, respectively. The CNT chirality also has a strong influence on the collapsed structure, leading to flat, warped and twisted CNTs, depending on the chiral angle

van der Waals interaction between a microparticle and a single-walled carbon nanotube

International Nuclear Information System (INIS)

Blagov, E. V.; Mostepanenko, V. M.; Klimchitskaya, G. L.

2007-01-01

The Lifshitz-type formulas describing the free energy and the force of the van der Waals interaction between an atom (molecule) and a single-walled carbon nanotube are obtained. The single-walled nanotube is considered as a cylindrical sheet carrying a two-dimensional free-electron gas with appropriate boundary conditions on the electromagnetic field. The obtained formulas are used to calculate the van der Waals free energy and force between a hydrogen atom (molecule) and single-walled carbon nanotubes of different radii. Comparison studies of the van der Waals interaction of hydrogen atoms with single-walled and multiwalled carbon nanotubes show that depending on atom-nanotube separation distance, the idealization of graphite dielectric permittivity is already applicable to nanotubes with only two or three walls

Electronic properties of single-walled chiral carbon nanotube

International Nuclear Information System (INIS)

Mensah, S.Y.; Allotey, F.K.A.; Mensah, N.G.; Nkrumah, G.

2001-09-01

The electronic properties of single-walled chiral carbon nanotube has been studied using the model based on infinitely long carbon atoms wrapped along a base helix of single-walled carbon nanotubes(SWNTs). The problem is solved semiclassically, and current density J, resistivity ρ, thermopower α z , and electrical power factor P calculated. It is noted that the current density j displays negative differential conductivity, whiles the resistivity ρ increases with increasing electrical field. ρ also slowly increases at low temperatures and then gradually increases with increasing temperature. The thermopower α z shows interesting behaviour. Very intriguing is the electrical power factor which shows relatively large values. (author)

Large eddy simulation of a mechanically ventilated compartment fire for nuclear applications

Energy Technology Data Exchange (ETDEWEB)

Xu, Bao P. [Dalian Univ. of Technology (China). Faculty of Energy and Power Engineering; Wen, Jennifer X. [Warwick Univ. (United Kingdom). Warwick FIRE, School of Engineering

2015-12-15

This paper deals with the modelling of a mechanically ventilated compartment fire which is a commonplace in nuclear fire scenarios. An advanced Computational Fluid Dynamics (CFD) field model with a wall conjugate heat transfer treatment is proposed. It simultaneously solves the compartment fire flow and the wall heat conduction. The flow solver is based on the Large Eddy Simulation (LES) based fire simulation solver FireFOAM within the frame of open source CFD code OpenFOAM {sup registered}. An extended eddy dissipation model is used to calculate the chemical reaction rate. A soot model based on the concept of smoke point height is employed to model the soot formation and oxidation. A finite volume method is adopted to model the radiative heat transfer. The ventilation flow is modelled by a simplified Bernoulli equation neglecting the detailed information on the ventilation system. The proposed model is validated against a single room fire test with forced mechanical ventilations. The predictions are in reasonably good agreement with experimental data.

Quantitative Analysis of Isolated Single-Wall Carbon Nanotubes with Their Molar Absorbance Coefficients

Directory of Open Access Journals (Sweden)

Shota Kuwahara

2014-01-01

Full Text Available The molar absorbance coefficients of metallic, semiconducting, and (6,5 chirality enriched single-wall carbon nanotubes were evaluated by a spray technique combined with atomic force microscopy. Single-wall carbon nanotubes with isolated and a single predominant electronic type were obtained by using the density-gradient ultracentrifugation technique. In the visible region, all coefficients had similar values around 2–5 × 109/mL mol−1 cm−1, independent of their diameter distribution and the electronic types of single-wall carbon nanotubes, and the εS22/εM11  and εS11/εM11 were estimated to be 1.0 and 4.0, respectively. The coefficient strongly depends on the length of single-wall carbon nanotubes, independent of their electronic types and chirality.

Molecular discriminators using single wall carbon nanotubes

International Nuclear Information System (INIS)

Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr; Ray, Nihar Ranjan; Sarkar, Sabyasachi

2012-01-01

The interaction between single wall carbon nanotubes (SWNTs) and amphiphilic molecules has been studied in a solid phase. SWNTs are allowed to interact with different amphiphilic probes (e.g. lipids) in a narrow capillary interface. Contact between strong hydrophobic and amphiphilic interfaces leads to a molecular restructuring of the lipids at the interface. The geometry of the diffusion front and the rate and the extent of diffusion of the interface are dependent on the structure of the lipid at the interface. Lecithin having a linear tail showed greater mobility of the interface as compared to a branched tail lipid like dipalmitoyl phosphatidylcholine, indicating the hydrophobic interaction between single wall carbon nanotube core and the hydrophobic tail of the lipid. Solid phase interactions between SWNT and lipids can thus become a very simple but efficient means of discriminating amphiphilic molecules in general and lipids in particular. (paper)

Fabrication of single-walled carbon nanohorns incorporated a monolithic column for capillary electrochromatography.

Science.gov (United States)

Zhao, Hongyan; Wang, Yizhou; Cheng, Heyong; Wang, Yuanchao

2017-08-01

Single-walled carbon nanohorns have received great interest for their unique properties and diverse potential applications. Herein, we demonstrated the feasibility of single-walled carbon nanohorns incorporated poly(styrene-divinylbenzene) monolith as the stationary phase for capillary electrochromatography, which were prepared by one-step in situ copolymerization. Single-walled carbon nanohorns were dispersed in styrene to give a stable and homogeneous suspension. The monolithic column gave effective separation for a wide range of aromatic compounds, which was based on hydrophobicity and π-π electrostatic stacking of single-walled carbon nanohorns. The precisions of migration time and peak area varied in the ranges of 1.4-1.9% for intraday trials and 1.7-3.5% for interday trials, and 3.2-6.7% for intraday trials and 4.1-7.4% for interday trials, and 3.6-7.2% for inter-column trials and 5.2-21.3% for inter-column trials, respectively, indicating the good reproducibility of single-walled carbon nanohorns embedded monolithic columns. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-pressure oxygenation of thin-wall YBCO single-domain samples

International Nuclear Information System (INIS)

Chaud, X; Savchuk, Y; Sergienko, N; Prikhna, T; Diko, P

2008-01-01

The oxygen annealing of ReBCO bulk material, necessary to achieve superconducting properties, usually induces micro- and macro-cracks. This leads to a crack-assisted oxygenation process that allows oxygenating large bulk samples faster than single crystals. But excellent superconducting properties are cancelled by the poor mechanical ones. More progressive oxygenation strategy has been shown to reduce drastically the oxygenation cracks. The problem then arises to keep a reasonable annealing time. The concept of bulk Y123 single-domain samples with thin-wall geometry has been introduced to bypass the inherent limitation due to a slow oxygen diffusion rate. But it is not enough. The use of a high oxygen pressure (16 MPa) enables to speed up further the process. It introduces a displacement in the equilibrium phase diagram towards higher temperatures, i.e., higher diffusion rates, to achieve a given oxygen content in the material. Remarkable results were obtained by applying such a high pressure oxygen annealing process on thin-wall single-domain samples. The trapped field of 16 mm diameter Y123 thin-wall single-domain samples was doubled (0.6T vs 0.3T at 77K) using an annealing time twice shorter (about 3 days). The initial development was made on thin bars. The advantage of thin-wall geometry is that such an annealing can be applied directly to a much larger sample

Noise characteristics of single-walled carbon nanotube network transistors

International Nuclear Information System (INIS)

Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun

2008-01-01

The noise characteristics of randomly networked single-walled carbon nanotubes grown directly by plasma enhanced chemical vapor deposition (PECVD) are studied with field effect transistors (FETs). Due to the geometrical complexity of nanotube networks in the channel area and the large number of tube-tube/tube-metal junctions, the inverse frequency, 1/f, dependence of the noise shows a similar level to that of a single single-walled carbon nanotube transistor. Detailed analysis is performed with the parameters of number of mobile carriers and mobility in the different environment. This shows that the change in the number of mobile carriers resulting in the mobility change due to adsorption and desorption of gas molecules (mostly oxygen molecules) to the tube surface is a key factor in the 1/f noise level for carbon nanotube network transistors

Improvements in Production of Single-Walled Carbon Nanotubes

Science.gov (United States)

Balzano, Leandro; Resasco, Daniel E.

2009-01-01

A continuing program of research and development has been directed toward improvement of a prior batch process in which single-walled carbon nanotubes are formed by catalytic disproportionation of carbon monoxide in a fluidized-bed reactor. The overall effect of the improvements has been to make progress toward converting the process from a batch mode to a continuous mode and to scaling of production to larger quantities. Efforts have also been made to optimize associated purification and dispersion post processes to make them effective at large scales and to investigate means of incorporating the purified products into composite materials. The ultimate purpose of the program is to enable the production of high-quality single-walled carbon nanotubes in quantities large enough and at costs low enough to foster the further development of practical applications. The fluidized bed used in this process contains mixed-metal catalyst particles. The choice of the catalyst and the operating conditions is such that the yield of single-walled carbon nanotubes, relative to all forms of carbon (including carbon fibers, multi-walled carbon nanotubes, and graphite) produced in the disproportionation reaction is more than 90 weight percent. After the reaction, the nanotubes are dispersed in various solvents in preparation for end use, which typically involves blending into a plastic, ceramic, or other matrix to form a composite material. Notwithstanding the batch nature of the unmodified prior fluidized-bed process, the fluidized-bed reactor operates in a continuous mode during the process. The operation is almost entirely automated, utilizing mass flow controllers, a control computer running software specific to the process, and other equipment. Moreover, an important inherent advantage of fluidized- bed reactors in general is that solid particles can be added to and removed from fluidized beds during operation. For these reasons, the process and equipment were amenable to

Vibrational Analysis of Curved Single-Walled Carbon Nanotube on a Pasternak Elastic Foundation

DEFF Research Database (Denmark)

Mehdipour, I.; Barari, Amin; Kimiaeifar, Amin

2012-01-01

. By utilizing He’s Energy Balance Method (HEBM), the relationships of the nonlinear amplitude and frequency were expressed for a curved, single-walled carbon nanotube. The amplitude frequency response curves of the nonlinear free vibration were obtained for a curved, single-walled carbon nanotube embedded...

View of the firing of a single engine OMS

Science.gov (United States)

1985-01-01

View of a single engine orbital maneuvering system (OMS) firing on the Discovery. The payload bay is open and the protective canisters for the AUSSAT communications satellite (open) and the ASC-1 are visible. A cloudy Earth's horizon can be seen above the orbiter.

Fabrication of ceramic wall tiles and their use in the uptake of radioactive 137Cs, 90Sr and 57Co

International Nuclear Information System (INIS)

Khalil, T.K.; El-Gammal, B.; Abou El-Nour, F.; Bossert, J.

2003-01-01

Egyptian waste materials as air cooled blast furanace slag's were added in different quantities to mixtures of egyptian raw materials applying the single fast firing technique for producing wall tiles. The physico-chemical characteristics of the waste materials as well as the raw materials were studied before and after the thermal treatment. The reactions occurred during the firing procces and the formation of the end phases were followed using DTA-TG, X-ray diffractometry and heating microscopy. The effect of composition on bend strength, water absorption and firing shrinkage was studied. As a result, promising wall tiles with high bend strength, low water absorption and low firing shrinkage, containing high percentage of waste materials (50 wt% of the slag) and fired at 1100degree C for 30 minures were fabricated

A Computational Experiment on Single-Walled Carbon Nanotubes

Science.gov (United States)

Simpson, Scott; Lonie, David C.; Chen, Jiechen; Zurek, Eva

2013-01-01

A computational experiment that investigates single-walled carbon nanotubes (SWNTs) has been developed and employed in an upper-level undergraduate physical chemistry laboratory course. Computations were carried out to determine the electronic structure, radial breathing modes, and the influence of the nanotube's diameter on the…

Single walled carbon nanotube network—Tetrahedral amorphous carbon composite film

Energy Technology Data Exchange (ETDEWEB)

Iyer, Ajai, E-mail: ajai.iyer@aalto.fi; Liu, Xuwen; Koskinen, Jari [Department of Materials Science and Engineering, School of Chemical Technology, Aalto University, POB 16200, 00076 Espoo (Finland); Kaskela, Antti; Kauppinen, Esko I. [NanoMaterials Group, Department of Applied Physics, School of Science, Aalto University, POB 15100, 00076 Espoo (Finland); Johansson, Leena-Sisko [Department of Forest Products Technology, School of Chemical Technology, Aalto University, POB 16400, 00076 Espoo (Finland)

2015-06-14

Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp{sup 3} bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

A triple quantum dot in a single-wall carbon nanotube

DEFF Research Database (Denmark)

Grove-Rasmussen, Kasper; Jørgensen, Henrik Ingerslev; Hayashi, T.

2008-01-01

A top-gated single-wall carbon nanotube is used to define three coupled quantum dots in series between two electrodes. The additional electron number on each quantum dot is controlled by top-gate voltages allowing for current measurements of single, double, and triple quantum dot stability diagrams...

Investigation on single carbon atom transporting through the single-walled carbon nanotube by MD simulation

International Nuclear Information System (INIS)

Ding Yinfeng; Zhang Zhibin; Ke Xuezhi; Zhu Zhiyuan; Zhu Dezhang; Wang Zhenxia; Xu Hongjie

2005-01-01

The single carbon atom transporting through the single-walled carbon nanotube has been studied by molecular-dynamics (MD) simulation. We got different trajectories of the carbon atom by changing the input parameters. The simulation results indicate that the single carbon atom with low energy can transport through the carbon nanotube under some input conditions and result in different trajectories being straight line or 'rosette' or circular. (authors)

Photovoltaic device using single wall carbon nanotubes and method of fabricating the same

Science.gov (United States)

Biris, Alexandru S.; Li, Zhongrui

2012-11-06

A photovoltaic device and methods for forming the same. In one embodiment, the photovoltaic device has a silicon substrate, and a film comprising a plurality of single wall carbon nanotubes disposed on the silicon substrate, wherein the plurality of single wall carbon nanotubes forms a plurality of heterojunctions with the silicon in the substrate.

Single wall carbon nanotube supports for portable direct methanol fuel cells.

Science.gov (United States)

Girishkumar, G; Hall, Timothy D; Vinodgopal, K; Kamat, Prashant V

2006-01-12

Single-wall and multiwall carbon nanotubes are employed as carbon supports in direct methanol fuel cells (DMFC). The morphology and electrochemical activity of single-wall and multiwall carbon nanotubes obtained from different sources have been examined to probe the influence of carbon support on the overall performance of DMFC. The improved activity of the Pt-Ru catalyst dispersed on carbon nanotubes toward methanol oxidation is reflected as a shift in the onset potential and a lower charge transfer resistance at the electrode/electrolyte interface. The evaluation of carbon supports in a passive air breathing DMFC indicates that the observed power density depends on the nature and source of carbon nanostructures. The intrinsic property of the nanotubes, dispersion of the electrocatalyst and the electrochemically active surface area collectively influence the performance of the membrane electrode assembly (MEA). As compared to the commercial carbon black support, single wall carbon nanotubes when employed as the support for anchoring the electrocatalyst particles in the anode and cathode sides of MEA exhibited a approximately 30% enhancement in the power density of a single stack DMFC operating at 70 degrees C.

Superconductivity in single wall carbon nanotubes

Directory of Open Access Journals (Sweden)

H Yavari

2009-08-01

Full Text Available   By using Greens function method we first show that the effective interaction between two electrons mediated by plasmon exchange can become attractive which in turn can lead to superconductivity at a high critical temperature in a singl wall carbon nanotubes (SWCNT. The superconducting transition temperature Tc for the SWCNT (3,3 obtained by this mechanism agrees with the recent experimental result. We also show as the radius of SWCNT increases, plasmon frequency becomes lower and leads to lower Tc.

Single-Walled Carbon Nanohorns for Energy Applications

Science.gov (United States)

Zhang, Zhichao; Han, Shuang; Wang, Chao; Li, Jianping; Xu, Guobao

2015-01-01

With the growth of the global economy and population, the demand for energy is increasing sharply. The development of environmentally a benign and reliable energy supply is very important and urgent. Single-walled carbon nanohorns (SWCNHs), which have a horn-shaped tip at the top of single-walled nanotube, have emerged as exceptionally promising nanomaterials due to their unique physical and chemical properties since 1999. The high purity and thermal stability, combined with microporosity and mesoporosity, high surface area, internal pore accessibility, and multiform functionalization make SWCNHs promising candidates in many applications, such as environment restoration, gas storage, catalyst support or catalyst, electrochemical biosensors, drug carrier systems, magnetic resonance analysis and so on. The aim of this review is to provide a comprehensive overview of SWCNHs in energy applications, including energy conversion and storage. The commonly adopted method to access SWCNHs, their structural modifications, and their basic properties are included, and the emphasis is on their application in different devices such as fuel cells, dye-sensitized solar cells, supercapacitors, Li-ion batteries, Li-S batteries, hydrogen storage, biofuel cells and so forth. Finally, a perspective on SWCNHs’ application in energy is presented. PMID:28347092

Single-Walled Carbon Nanohorns for Energy Applications

Directory of Open Access Journals (Sweden)

Zhichao Zhang

2015-10-01

Full Text Available With the growth of the global economy and population, the demand for energy is increasing sharply. The development of environmentally a benign and reliable energy supply is very important and urgent. Single-walled carbon nanohorns (SWCNHs, which have a horn-shaped tip at the top of single-walled nanotube, have emerged as exceptionally promising nanomaterials due to their unique physical and chemical properties since 1999. The high purity and thermal stability, combined with microporosity and mesoporosity, high surface area, internal pore accessibility, and multiform functionalization make SWCNHs promising candidates in many applications, such as environment restoration, gas storage, catalyst support or catalyst, electrochemical biosensors, drug carrier systems, magnetic resonance analysis and so on. The aim of this review is to provide a comprehensive overview of SWCNHs in energy applications, including energy conversion and storage. The commonly adopted method to access SWCNHs, their structural modifications, and their basic properties are included, and the emphasis is on their application in different devices such as fuel cells, dye-sensitized solar cells, supercapacitors, Li-ion batteries, Li-S batteries, hydrogen storage, biofuel cells and so forth. Finally, a perspective on SWCNHs’ application in energy is presented.

Methods for Gas Sensing with Single-Walled Carbon Nanotubes

Science.gov (United States)

Kaul, Anupama B. (Inventor)

2013-01-01

Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

Plasma excitations in a single-walled carbon nanotube

Indian Academy of Sciences (India)

The effect of different uniform transverse external magnetic fields in plasma frequency when propagated parallel to the surface of the single-walled metallic carbon nanotubes is studied. The classical electrodynamics as well as Maxwell's equations are used in the calculations. Equations are developed for both short- and ...

Finite element modeling of single-walled carbon nanotubes with introducing a new wall thickness

International Nuclear Information System (INIS)

Jalalahmadi, B; Naghdabadi, R

2007-01-01

A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. By considering the covalent bonds as connecting elements between carbon atoms, a nanotube is simulated as a space frame-like structure. Here, the carbon atoms act as joints of the connecting elements. To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. Using Morse atomic potential, the elastic moduli of beam elements are obtained via considering a linkage between molecular and continuum mechanics. Also, a new wall thickness ( bond diameter) equal to 0.1296 nm is introduced. In order to demonstrate the applicability of FE model and new wall thickness, the influence of tube wall thickness, diameter and chirality on the Young's modulus of SWCNTs is investigated. It is found that the choice of wall thickness significantly affects the calculation of Young's modulus. For the values of wall thickness used in the literature, the Young's moduli are estimated which agree very well with the corresponding theoretical results and experimental measurements. We also investigate the dependence of elastic moduli on diameter and chirality of the nanotube. The larger tube diameter, the higher Young's modulus of SWCNT. The Young's modulus of chiral SWCNTs is found to be generally larger than that of armchair and zigzag SWCNTs. The presented results demonstrate that the proposed FE model and wall thickness may provide a valuable tool for studying the mechanical behavior of carbon nanotubes and their application in nano-composites

Dependence of the electrical properties of defective single-walled carbon nanotubes on the vacancy density

International Nuclear Information System (INIS)

Luo Yu-Pin; Tien Li-Gan; Tsai Chuen-Horng; Lee Ming-Hsien; Li Feng-Yin

2011-01-01

The relationship between the electric properties and the vacancy density in single-walled carbon nanotubes has been investigated from first principles as well as the dependence of the influencing range of a vacancy in the nanotube on the nanotube chirality. Compared with the long-range interaction of the vacancies in a single-walled carbon nanotube with non-zero chiral angle, a much shorter interaction was found between vacancies in a zigzag single-walled carbon nanotube. In this study, we investigated the bandstructure fluctuations caused by the nanotube strain, which depends on both the vacancy density and the tube chirality. These theoretical results provide new insight to understand the relationship between the local deformation of a defective single-walled carbon nanotube and its measurable electronic properties. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Analytical approach to phonons and electron-phonon interactions in single-walled zigzag carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Kandemir, B S; Keskin, M [Department of Physics, Faculty of Sciences, Ankara University, 06100 Tandogan, Ankara (Turkey)

2008-08-13

In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction.

Analytical approach to phonons and electron-phonon interactions in single-walled zigzag carbon nanotubes

International Nuclear Information System (INIS)

Kandemir, B S; Keskin, M

2008-01-01

In this paper, exact analytical expressions for the entire phonon spectra in single-walled carbon nanotubes with zigzag geometry are presented by using a new approach, originally developed by Kandemir and Altanhan. This approach is based on the concept of construction of a classical lattice Hamiltonian of single-walled carbon nanotubes, wherein the nearest and next nearest neighbor and bond bending interactions are all included, then its quantization and finally diagonalization of the resulting second quantized Hamiltonian. Furthermore, within this context, explicit analytical expressions for the relevant electron-phonon interaction coefficients are also investigated for single-walled carbon nanotubes having this geometry, by the phonon modulation of the hopping interaction

Dispersion of Single Wall Carbon Nanotubes by in situ Polymerization Under Sonication

Science.gov (United States)

Park, Cheol; Ounaies, Zoubeida; Watson, Kent A.; Crooks, Roy E.; Smith, Joseph, Jr.; Lowther, Sharon E.; Connell, John W.; Siochi, Emilie J.; Harrison, Joycelyn S.; St.Clair, Terry L.

2002-01-01

Single wall nanotube reinforced polyimide nanocomposites were synthesized by in situ polymerization of monomers of interest in the presence of sonication. This process enabled uniform dispersion of single wall carbon nanotube (SWNT) bundles in the polymer matrix. The resultant SWNT-polyimide nanocomposite films were electrically conductive (antistatic) and optically transparent with significant conductivity enhancement (10 orders of magnitude) at a very low loading (0.1 vol%). Mechanical properties as well as thermal stability were also improved with the incorporation of the SWNT.

Single-walled carbon nanotube-induced mitotic disruption⋆

OpenAIRE

Sargent, L.M.; Hubbs, A.F.; Young, S.-H.; Kashon, M.L.; Dinu, C.Z.; Salisbury, J.L.; Benkovic, S.A.; Lowry, D.T.; Murray, A.R.; Kisin, E.R.; Siegrist, K.J.; Battelli, L.; Mastovich, J.; Sturgeon, J.L.; Bunker, K.L.

2011-01-01

Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 μg/cm2 single-walled c...

Design of Fire/Gas Penetration Seals and fire exposure tests for Tokamak Fusion Test Reactor experimental areas

International Nuclear Information System (INIS)

Cavalluzzo, S.

1983-01-01

A Fire/Gas Penetration Seal is required in every penetration through the walls and ceilings into the Test Cell housing the Tokamak Fusion Test Reactor (TFTR), as well as other adjacent areas to protect the TFTR from fire damage. The penetrations are used for field coil lead stems, diagnostics systems, utilities, cables, trays, mechanical devices, electrical conduits, vacuum liner, air conditioning ducts, water pipes, and gas pipes. The function of the Fire/Gas Penetration Seals is to prevent the passage of fire and products of combustion through penetrations for a period of time up to three hours and remain structurally intact during fire exposure. The Penetration Seal must withstand, without rupture, a fire hose water stream directed at the hot surface. There are over 3000 penetrations ranging in size from several square inches to 100 square feet, and classified into 90 different types. The material used to construct the Fire/Gas Penetration Seals consist of a single and a two-component room temperature vulcanizing (RTV) silicone rubber compound. Miscellaneous materials such as alumina silica refractory fibers in board, blanket and fiber forms are also used in the construction and assembly of the Seals. This paper describes some of the penetration seals and the test procedures used to perform the three-hour fire exposure tests to demonstrate the adequacy of the seals

The effect of fibronectin on structural and biological properties of single walled carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Mottaghitalab, Fatemeh [Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Farokhi, Mehdi [National cell bank of Iran, Pasteur Institute, Tehran (Iran, Islamic Republic of); Atyabi, Fatemeh [Department of Pharmaceutical Nanoechnology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Omidvar, Ramin [Department of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali, E-mail: mashokrgozar@pasteur.ac.ir [National cell bank of Iran, Pasteur Institute, Tehran (Iran, Islamic Republic of); Sadeghizadeh, Majid, E-mail: sadeghma@modares.ac.ir [Department Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

2015-06-01

Highlights: • Increasing the cytocompatibility of single walled carbon nanotube by loading fibronectin. • Enhancing the hydrophilicity and nanosurface roughness of single walled carbon nanotube after loading fibronectin. • Fibronectin makes the surface properties of single walled carbon nanotube more suitable for cell proliferation and growth. - Abstract: Despite the attractive properties of carbon nanotubes (CNTs), cytoxicity and hydrophobicity are two main considerable features which limit their application in biomedical fields. It was well established that treating CNTs with extracellular matrix components could reduce these unfavourable characteristics. In an attempt to address these issues, fibronectin (FN) with different concentrations was loaded on single walled carbon nanotubes (SWCNTs) substrate. Scanning electron microscope, atomic force microscopy (AFM), contact angles and X-ray photoelectron spectroscopy (XPS) were preformed in order to characterize FN loaded SWCNTs substrates. According to XPS and AFM results, FN could interact with SWCNTs and for this, the hydrophilicity of SWCNTs was improved. Additionally, SWCNT modified with FN showed less cytotoxicity compared with neat SWCNT. Finally, FN was shown to act as an interesting extracellular component for enhancing the biological properties of SWCNT.

The effect of fibronectin on structural and biological properties of single walled carbon nanotube

International Nuclear Information System (INIS)

Mottaghitalab, Fatemeh; Farokhi, Mehdi; Atyabi, Fatemeh; Omidvar, Ramin; Shokrgozar, Mohammad Ali; Sadeghizadeh, Majid

2015-01-01

Highlights: • Increasing the cytocompatibility of single walled carbon nanotube by loading fibronectin. • Enhancing the hydrophilicity and nanosurface roughness of single walled carbon nanotube after loading fibronectin. • Fibronectin makes the surface properties of single walled carbon nanotube more suitable for cell proliferation and growth. - Abstract: Despite the attractive properties of carbon nanotubes (CNTs), cytoxicity and hydrophobicity are two main considerable features which limit their application in biomedical fields. It was well established that treating CNTs with extracellular matrix components could reduce these unfavourable characteristics. In an attempt to address these issues, fibronectin (FN) with different concentrations was loaded on single walled carbon nanotubes (SWCNTs) substrate. Scanning electron microscope, atomic force microscopy (AFM), contact angles and X-ray photoelectron spectroscopy (XPS) were preformed in order to characterize FN loaded SWCNTs substrates. According to XPS and AFM results, FN could interact with SWCNTs and for this, the hydrophilicity of SWCNTs was improved. Additionally, SWCNT modified with FN showed less cytotoxicity compared with neat SWCNT. Finally, FN was shown to act as an interesting extracellular component for enhancing the biological properties of SWCNT

The forced sound transmission of finite single leaf walls using a variational technique.

Science.gov (United States)

Brunskog, Jonas

2012-09-01

The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements and alternative theory, with reasonable agreement.

The forced sound transmission of finite single leaf walls using a variational technique

DEFF Research Database (Denmark)

Brunskog, Jonas

2012-01-01

The single wall is the simplest element of concern in building acoustics, but there still remain some open questions regarding the sound insulation of this simple case. The two main reasons for this are the effects on the excitation and sound radiation of the wall when it has a finite size......, and the fact that the wave field in the wall is consisting of two types of waves, namely forced waves due to the exciting acoustic field, and free bending waves due to reflections in the boundary. The aim of the present paper is to derive simple analytical formulas for the forced part of the airborne sound...... insulation of a single homogeneous wall of finite size, using a variational technique based on the integral-differential equation of the fluid loaded wall. The so derived formulas are valid in the entire audible frequency range. The results are compared with full numerical calculations, measurements...

Transient reflectivity on vertically aligned single-wall carbon nanotubes

NARCIS (Netherlands)

Galimberti, Gianluca; Ponzoni, Stefano; Ferrini, Gabriele; Hofmann, Stephan; Arshad, Muhammad; Cepek, Cinzia; Pagliara, Stefania

2013-01-01

One-color transient reflectivity measurements are carried out on two different samples of vertically aligned single-wall carbon nanotube bundles and compared with the response recently published on unaligned bundles. The negative sign of the optical response for both samples indicates that the free

Analyses of Concrete Structures Exposed to Fire

DEFF Research Database (Denmark)

Hertz, Kristian

The text book contains the data and methods necessary for fire safety design of concrete constructions. The methods relate to standard fire as well as to any time of any other fire course.Material data are presented for concretes exposed to fire, and calculation methods are given for the ultimate...... bending capacity of beams and slabs, the ultimate shear capacity of beams, for the instability of columns and walls and for the deflection of prestressed and non-prestressed beams, slabs, walls and columns.All methods have been derived and compared to tests by Kristian Hertz....

Reduction of single-walled carbon nanotube diameter to sub-nm via feedstock

Energy Technology Data Exchange (ETDEWEB)

Thurakitseree, T.; Zhao, Pei; Chiashi, Shohei; Maruyama, Shigeo [Department of Mechanical Engineering, University of Tokyo (Japan); Kramberger, Christian [Faculty of Physics, University of Vienna (Austria); Einarsson, Erik [Department of Mechanical Engineering, University of Tokyo (Japan); Global Center of Excellence for Mechanical Systems Innovation, University of Tokyo (Japan)

2012-12-15

Vertically aligned single-walled carbon nanotube arrays were synthesized from dip-coated binary Co/Mo catalyst by no-flow chemical vapor deposition (CVD) from either pure ethanol or acetonitrile as carbon feedstock. By changing to acetonitrile the mean diameter was reduced from 2.1 nm to less than 1.0 nm despite using identically prepared catalyst. The demonstrated diameter control on flat substrates is a versatile approach towards the direct synthesis of tailored single-walled carbon nanotubes. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Thermogravimetric Analysis of Single-Wall Carbon Nanotubes

Science.gov (United States)

Arepalli, Sivram; Nikolaev, Pavel; Gorelik, Olga

2010-01-01

An improved protocol for thermogravimetric analysis (TGA) of samples of single-wall carbon nanotube (SWCNT) material has been developed to increase the degree of consistency among results so that meaningful comparisons can be made among different samples. This improved TGA protocol is suitable for incorporation into the protocol for characterization of carbon nanotube material. In most cases, TGA of carbon nanotube materials is performed in gas mixtures that contain oxygen at various concentrations. The improved protocol is summarized.

Titanium dioxide, single-walled carbon nanotube composites

Science.gov (United States)

Yao, Yuan; Li, Gonghu; Gray, Kimberly; Lueptow, Richard M.

2015-07-14

The present invention provides titanium dioxide/single-walled carbon nanotube composites (TiO.sub.2/SWCNTs), articles of manufacture, and methods of making and using such composites. In certain embodiments, the present invention provides membrane filters and ceramic articles that are coated with TiO.sub.2/SWCNT composite material. In other embodiments, the present invention provides methods of using TiO.sub.2/SWCNT composite material to purify a sample, such as a water or air sample.

A new method of preparing single-walled carbon nanotubes

Indian Academy of Sciences (India)

A novel method of purification for single-walled carbon nanotubes, prepared by an arc-discharge method, is described. The method involves a combination of acid washing followed by high temperature hydrogen treatment to remove the metal nanoparticles and amorphous carbon present in the as-synthesized singlewalled ...

Phonon and thermal properties of achiral single wall carbon ...

Indian Academy of Sciences (India)

A detailed theoretical study of the phonon and thermal properties of achiral single wall carbon nanotubes has been carried out using force constant model considering up to third nearest-neighbor interactions. We have calculated the phonon dispersions, density of states, radial breathing modes (RBM) and the specific heats ...

Giant electrical power factor in single-walled chiral carbon nanotube

International Nuclear Information System (INIS)

Mensah, S.Y.; Allotey, F.K.A.; Mensah, N.G.; Nkrumah, G.

2001-10-01

Using the semiclassical approach we studied the thermoelectrical properties of single-walled chiral carbon nanotubes (SWNTs). We predict a giant electrical power factor and hence proposed the use of carbon nanotubes as thermoelements for refrigeration. (author)

Single-Walled Carbon Nanotubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

Directory of Open Access Journals (Sweden)

Venkata K. K. Upadhyayula

2008-01-01

Full Text Available The possibility of using single-walled carbon nanotubes (SWCNTs aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k for S.aureus and E.coli determined from batch adsorption study was found to be 9×108 and 2×108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

A black body absorber from vertically aligned single-walled carbon nanotubes

Science.gov (United States)

Mizuno, Kohei; Ishii, Juntaro; Kishida, Hideo; Hayamizu, Yuhei; Yasuda, Satoshi; Futaba, Don N.; Yumura, Motoo; Hata, Kenji

2009-01-01

Among all known materials, we found that a forest of vertically aligned single-walled carbon nanotubes behaves most similarly to a black body, a theoretical material that absorbs all incident light. A requirement for an object to behave as a black body is to perfectly absorb light of all wavelengths. This important feature has not been observed for real materials because materials intrinsically have specific absorption bands because of their structure and composition. We found a material that can absorb light almost perfectly across a very wide spectral range (0.2–200 μm). We attribute this black body behavior to stem from the sparseness and imperfect alignment of the vertical single-walled carbon nanotubes. PMID:19339498

Inelastic x-ray study of plasmons in oriented single and multi-walled carbon nanotubes

International Nuclear Information System (INIS)

Casa, D.M.; Upton, M.H.; Gog, T.; Misewich, J.; Hill, J.P.; Lowndes, D.; Eres, G.

2006-01-01

Carbon nanotubes (CNT) have a wide variety of interesting properties and a large number of potential aplications in electronic and optical devices. In this study we concentrate on one important aspect of their electronic stucture: the plasmon dispersions in both single- and multi-wall CNTs and their relation to those in graphite. For the first time inelastic X-ray scattering is used to study these collective electronic excitations in oriented CNT samples. The experiments were performed on the IXS instrument at beamline 9ID CMC-XOR, APS, ANL. The incident energy was defined by a Si(333) monochromator, a spherically bent Ge(733) diced analyzer at the end of a 1-m arm focused the incident radiation onto a solid-state detector. The overall resolution was ∼300 meV FWHM. The incident photons were linearly polarized perpendicular to the scattering plane. Energy loss scans were taken by varying the incident energy while keeping the exit energy fixed at 8.9805 keV. The momentum transfer was kept along the nanotubes axis. Spectra were taken at room temperature. The samples were oriented CNTs (both single- and multi-wall) grown on a Si substrate. The samples referred to as 'single-wall' were in fact a few walls at most (1-5) while the multi-walled ones had ∼12 walls. Fig. 1. shows the inelastic spectra for the single-, multi-wall, and highly oriented pyrolithic graphite (HOPG) from top to bottom. Momentum transfer was Q = 0.79 (angstrom) -1 in all cases, its direction was along the tubes for the first two samples or parallel to the sheets for graphite. The peaks at ∼10 and ∼30 eV are known as the π and σ + π plasmons respectively. Fig. 2. shows the complete dispersion curves for both plasmon modes as a function of momentum transfer for all three samples.

Single-Wall Carbon Nanotube-Coated Cotton Yarn for Electrocardiography Transmission

Directory of Open Access Journals (Sweden)

Yuliang Zhao

2018-03-01

Full Text Available We fabricated a type of conductive fabric, specifically single-wall carbon nanotube-coated cotton yarns (SWNT-CYs, for electrocardiography (ECG signal transmission utilizing a “dipping and drying” method. The conductive cotton yarns were prepared by dipping cotton yarns in SWNTs (single-wall carbon nanotubes solutions and then drying them at room temperature—a simple process that shows consistency in successfully coating cotton yarns with conductive carbon nanotubes (CNTs. The influence of fabrication conditions on the conductivity properties of SWNT-CYs was investigated. The results demonstrate that our conductive yarns can transmit weak bio-electrical (i.e., ECG signals without significant attenuation and distortion. Our conductive cotton yarns, which combine the flexibility of conventional fabrics and the good conductivity of SWNTs, are promising materials for wearable electronics and sensor applications in the future.

Fire propagation over combustible exterior facades exposed to intensified flame in Japan

Directory of Open Access Journals (Sweden)

Nishio Yuhei

2016-01-01

Full Text Available With regard to fire safety for exterior walls of a building, fire-resistance performance is considered, according to the current Building Standard Law of Japan. And it was revealed that the fire safety is not specifically regulated from the viewpoint of reaction-to-fire performance, such as fire propagation caused by combustible materials or products installed on the exterior side of fire-resistant load-bearing walls. Actual fire incidents in the world have shown that massive façade fire could occur at the exterior side of building wall even when the wall itself is fire resistant. In previous studies of the authors, a test method of façade fire was proposed for evaluating the vertical fire propagation over an external wall within the same building [1,2]. Based on these studies, new domestic standard test method was established in Japan as JIS A 1310: 2015, “Test method for fire propagation over building façades” at the end of January 2015 [3]. But there was the argument that heat output of burner inside the combustion chamber was not sufficiently high in the previous study. In this paper, results of fire tests on combustible façades are discussed from the viewpoints of different strength of flame exposing facade. In this research, it was clearly found that JIS A 1310 with heat output of 900kW could be applicable for evaluating fire propagation behaviour over various types of combustible exterior façades.

Binding energy and mechanical stability of single- and multi-walled carbon nanotube serpentines

International Nuclear Information System (INIS)

Zhao, Junhua; Lu, Lixin; Rabczuk, Timon

2014-01-01

Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] and Machado et al. [Phys. Rev. Lett. 110, 105502 (2013)] reported the experimental and molecular dynamics realization of S-like shaped single-walled carbon nanotubes (CNTs), the so-called CNT serpentines. We reported here results from continuum modeling of the binding energy γ between different single- and multi-walled CNT serpentines and substrates as well as the mechanical stability of the CNT serpentine formation. The critical length for the mechanical stability and adhesion of different CNT serpentines are determined in dependence of E i I i , d, and γ, where E i I i and d are the CNT bending stiffness and distance of the CNT translation period. Our continuum model is validated by comparing its solution to full-atom molecular dynamics calculations. The derived analytical solutions are of great importance for understanding the interaction mechanism between different single- and multi-walled CNT serpentines and substrates

Synthesis of single walled carbon nanotubes by dual laser vaporization

CSIR Research Space (South Africa)

Moodley, MK et al.

2006-02-27

Full Text Available Single-walled carbon nanotubes were synthesised by the laser vaporisation of graphite composite targets in a tube furnace. Two pulsed Nd:YAG lasers operating at fundamental (1 064 nm) and 2nd harmonic (532 nm) were combined, focused and evaporated...

Sonochemical optimization of the conductivity of single wall nanotube networks

NARCIS (Netherlands)

Kaempgen, M.; Lebert, M.; Haluska, M.; Nicoloso, N.; Roth, S.

2008-01-01

Networks of single-wall carbon nanotubes (SWCNTs) are covalently functionalized with oxygen-containing groups. In lower concentration, these functional groups act as stable dopands improving the conductivity of the SWCNT material. In higher concentration however, their role as defects with a certain

Synthesis of single walled carbon nanotubes by dual laser vaporization

CSIR Research Space (South Africa)

Moodley, MK

2006-07-01

Full Text Available Single walled carbon nanotubes were synthesized by the laser vaporization of graphite composite targets in a tube furnace. Two pulsed Nd:Yag lasers operating at fundamental (1064 nm) and 2 nd harmonic (532 nm) were combined, focused and evaporated...

Hydrogen adsorption on N-decorated single wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Rangel, Eduardo [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Ruiz-Chavarria, Gregorio [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Departamento de Fisica, Facultad de Ciencias, Universidad Nacional Autonoma de Mexico Ciudad Universitaria, Codigo Postal 04510, Mexico D.F. (Mexico); Magana, L.F., E-mail: fernando@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, Codigo Postal 01000, Mexico D.F. (Mexico); Arellano, J.S. [Departamento de Ciencias Basicas, Universidad Autonoma Metropolitana, Unidad Azcapotzalco. Avenida San Pablo No. 180, Col. Reynosa Tamaulipas Codigo Postal 02200, Mexico D.F. (Mexico)

2009-07-06

Using density functional theory and molecular dynamics we found that N-decorated single walled (8,0) carbon nanotubes are potential high capacity hydrogen storage media. This system could store up to 6.0 wt% hydrogen at 300 K and ambient pressure, with average adsorption energy of -80 meV/(H{sub 2}). Nitrogen coverage was C{sub 8}N.

Hydrogen adsorption on N-decorated single wall carbon nanotubes

International Nuclear Information System (INIS)

Rangel, Eduardo; Ruiz-Chavarria, Gregorio; Magana, L.F.; Arellano, J.S.

2009-01-01

Using density functional theory and molecular dynamics we found that N-decorated single walled (8,0) carbon nanotubes are potential high capacity hydrogen storage media. This system could store up to 6.0 wt% hydrogen at 300 K and ambient pressure, with average adsorption energy of -80 meV/(H 2 ). Nitrogen coverage was C 8 N.

Electrochemical Charging of Individual Single-Walled Carbon Nanotubes

Czech Academy of Sciences Publication Activity Database

Kalbáč, Martin; Farhat, H.; Kavan, Ladislav; Kong, J.; Sasaki, K.; Saito, R.; Dresselhaus, M. S.

2009-01-01

Roč. 3, č. 8 (2009), s. 2320-2328 ISSN 1936-0851 R&D Projects: GA ČR GC203/07/J067; GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : single-walled carbon nanotubes * Raman spectroscopy * electrochemical gating * spectroelectrochemistry Subject RIV: CG - Electrochemistry Impact factor: 7.493, year: 2009

Fire protection in Angra-2 nuclear power plant. The use of fire protection collars on plastic piping systems

International Nuclear Information System (INIS)

Oliveira Segabinaze, R. de

1994-01-01

The object of this paper is to briefly the use of fire protection collars on plastic piping systems passing through wall and floor penetration. The fire protection collars consist of a stainless steel housing, in which the leading edges of two pivoting plates are in constant pressure contact with the pipe. In case of fire these plates react on the softened pipe with a guillotine action, thereby stopping the flow; within the housing a foam material expands to fill the space when subject to the heat of the fire. The piping project has to be modified to permit the fixing of the collars to walls and floor penetrations. (author). 2 refs, 9 figs

Optical Characterization and Applications of Single Walled Carbon Nanotubes

Science.gov (United States)

Strano, Michael S.

2005-03-01

Recent advances in the dispersion and separation of single walled carbon nanotubes have led to new methods of optical characterization and some novel applications. We find that Raman spectroscopy can be used to probe the aggregation state of single-walled carbon nanotubes in solution or as solids with a range of varying morphologies. Carbon nanotubes experience an orthogonal electronic dispersion when in electrical contact that broadens (from 40 meV to roughly 80 meV) and shifts the interband transition to lower energy (by 60 meV). We show that the magnitude of this shift is dependent on the extent of bundle organization and the inter-nanotube contact area. In the Raman spectrum, aggregation shifts the effective excitation profile and causes peaks to increase or decrease, depending on where the transition lies, relative to the excitation wavelength. The findings are particularly relevant for evaluating nanotube separation processes, where relative peak changes in the Raman spectrum can be confused for selective enrichment. We have also used gel electrophoresis and column chromatography conducted on individually dispersed, ultrasonicated single-walled carbon nanotubes to yield simultaneous separation by tube length and diameter. Electroelution after electrophoresis is shown to produce highly resolved fractions of nanotubes with average lengths between 92 and 435 nm. Separation by diameter is concomitant with length fractionation, and nanotubes that have been cut shortest also possess the greatest relative enrichments of large-diameter species. The relative quantum yield decreases nonlinearly as the nanotube length becomes shorter. These findings enable new applications of nanotubes as sensors and biomarkers. Particularly, molecular detection using near infrared (n-IR) light between 0.9 and 1.3 eV has important biomedical applications because of greater tissue penetration and reduced auto-fluorescent background in thick tissue or whole blood media. Carbon nanotubes

A Method of Fire Scenarios Identification in a Consolidated Fire Risk Analysis

International Nuclear Information System (INIS)

Lim, Ho Gon; Han, Sang Hoon; Yang, Joon Eon

2010-01-01

Conventional fire PSA consider only two cases of fire scenarios, that is one for fire without propagation and the other for single propagation to neighboring compartment. Recently, a consolidated fire risk analysis using single fault tree (FT) was developed. However, the fire scenario identification in the new method is similar to conventional fire analysis method. The present study develops a new method of fire scenario identification in a consolidated fire risk analysis method. An equation for fire propagation is developed to identify fire scenario and a mapping method of fire scenarios into internal event risk model is discussed. Finally, an algorithm for automatic program is suggested

The effect of water jet lancing on furnace wall tubes of high slagged deposit fuel-fired boilers

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, V V; Kovalevitch, I A; Maidanik, M N [All-Union Heat Engineering Institute, Siberian Branch, Krasnoyarsk (USSR)

1990-01-01

In this paper the results of investigating the effectiveness of water jet lancing on furnace wall tubes of slagged deposits fuels fired boilers type E-500, P-64, P-67 are given. The boilers of these types are designed to burn Jugoslavian lignites are Beresovo lignites of the Kansk-Achinsk deposits. Recommendations for usage of low retractable, long retractable and long-range water blowers, depending on the design, produced in the USSR, the furnace dimension and stability of deposits are given as well.

Fire barrier evaluation of the wall between spent nuclear fuel storage basins and reactor areas, 105KE and 105KW

International Nuclear Information System (INIS)

Johnson, B.H.

1994-01-01

This evaluation is intended to provide a comprehensive assessment of the risks from fire and fire related perils for the fire barriers between spent nuclear fuel storage basins and reactor areas, 105KE and 105KW. As a result of this fire barrier evaluation the present walls and the components thereof are not a true listed fire rated assembly. However, due to the construction of these barriers and the components thereof, these barriers will provide an equivalent level of protection provided the recommendations in Section 8.0 of this report are completed. These recommended upgrades are based upon sound engineering practice by a Registered Fire Protection Engineer. The construction of the barrier are substantial enough to provide the required 2-hr fire resistance rating. The primary concern is the numerous penetrations in the barrier. There are many penetrations that are adequate and no additional work is required. These penetrations are the ones that were poured-in-place at the time of construction. The penetrations that are of concern are some of the doors, the HVAC ducts, and the unsealed piping and conduit penetrations. There are several metal doors that should be replaced because the existing doors have either a non-approved window or louver that will not limit the spread of fire to one side of the barrier. All unsealed piping and conduit penetrations should be firestopped with an approved firestopping material. The existing non-active ducts that pass through the barrier should be disconnected at the barrier and the opening sealed with an approved firestopping method

Single-Walled Carbon Nano tubes as Fluorescence Biosensors for Pathogen Recognition in Water Systems

International Nuclear Information System (INIS)

Upadhyayula, V.K.K

2008-01-01

The possibility of using single-walled carbon nanotubes (SWCNTs) aggregates as fluorescence sensors for pathogen recognition in drinking water treatment applications has been studied. Batch adsorption study is conducted to adsorb large concentrations of Staphylococcus aureus aureus SH 1000 and Escherichia coli pKV-11 on single-walled carbon nanotubes. Subsequently the immobilized bacteria are detected with confocal microscopy by coating the nanotubes with fluorescence emitting antibodies. The Freundlich adsorption equilibrium constant (k) for S.aureus and E.coli determined from batch adsorption study was found to be 9 x108 and 2 x108 ml/g, respectively. The visualization of bacterial cells adsorbed on fluorescently modified carbon nanotubes is also clearly seen. The results indicate that hydrophobic single-walled carbon nanotubes have excellent bacterial adsorption capacity and fluorescent detection capability. This is an important advancement in designing fluorescence biosensors for pathogen recognition in water systems.

Synthesis of dark brown single-walled carbon nanotubes and their

Indian Academy of Sciences (India)

We report here a simple and effective approach to the covalent attachment of single-walled carbon nanotubes (SWCNTs) and azo compounds. The functionalized SWCNTs prepared (through a radical mechanism) have been used for a diazonium coupling reaction. The results showed that the chemical method used has ...

Synthesis of dark brown single-walled carbon nanotubes and their ...

Indian Academy of Sciences (India)

Abstract. We report here a simple and effective approach to the covalent attachment of single-walled carbon nanotubes (SWCNTs) and azo compounds. The functionalized SWCNTs prepared (through a radical mecha- nism) have been used for a diazonium coupling reaction. The results showed that the chemical method ...

Theoretical study on the combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes

International Nuclear Information System (INIS)

Wang, Guo; Huang, Yuanhe

2012-01-01

Highlights: ► The combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes are investigated. ► The band structures and related electronic properties are calculated by using crystal orbital method. ► The carrier mobility and mean free path are evaluated under the deformation potential theory. -- Abstract: The combined systems of peanut-shaped carbon nanotubes encapsulated in both semiconducting and metallic single-walled carbon nanotubes are investigated by using self-consistent field crystal orbital method based on the density functional theory. The investigation indicates that the interaction between the two constituents is mainly contributed by the π orbitals. The encapsulation does not change the semiconducting or metallic nature of the single-walled carbon nanotubes, but significantly changes the band dispersion and decreases the frontier band width of the metallic one. The carrier mobility and mean free path of the metallic single-walled carbon nanotube increase greatly after the encapsulation. The calculated mobilities have the order of 10 3 cm 2 V −1 s −1 for both of the semiconducting and metallic double-walled carbon nanotubes.

Production and characterization of polymer nanocomposite with aligned single wall carbon nanotubes

International Nuclear Information System (INIS)

Chen Wei; Tao Xiaoming

2006-01-01

We reported a simple method to fabricate polymer nanocomposites with single-walled carbon nanotubes (SWNTs) having exceptional alignment and improved mechanical properties. The composite films were fabricated by casting a suspension of single walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. The orientation as well as dispersion of nanotubes was determined by scanning electron microscopy, transmission electron microscopy and polarized Raman spectroscopy. The macroscopic alignment probably results from solvent-polymer interaction induced orientation of soft segment chain during swelling and moisture curing. The tensile behavior of the aligned nanotube composite film was also studied. At a 0.5 wt.% nanotube loading, a 1.9-fold increase in Young's modulus was achieved

Magnetoexcitons and Faraday rotation in single-walled carbon nanotubes and graphene nanoribbons

Science.gov (United States)

Have, Jonas; Pedersen, Thomas G.

2018-03-01

The magneto-optical response of single-walled carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) is studied theoretically, including excitonic effects. Both diagonal and nondiagonal response functions are obtained and employed to compute Faraday rotation spectra. For single-walled CNTs in a parallel field, the results show field-dependent splitting of the exciton absorption peaks caused by brightening a dark exciton state. Similarly, for GNRs in a perpendicular magnetic field, we observe a field-dependent shift of the exciton peaks and the emergence of an absorption peak above the energy gap. Results show that excitonic effects play a significant role in the optical response of both materials, particularly for the off-diagonal tensor elements.

Alignment enhanced photoconductivity in single wall carbon nanotube films

International Nuclear Information System (INIS)

Liu Ye; Lu Shaoxin; Panchapakesan, Balaji

2009-01-01

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

Transition of spiral calcium waves between multiple stable patterns can be triggered by a single calcium spark in a fire-diffuse-fire model

Science.gov (United States)

Tang, Ai-Hui; Wang, Shi-Qiang

2009-01-01

Spiral patterns have been found in various nonequilibrium systems. The Ca2+-induced Ca2+ release system in single cardiac cells is unique for highly discrete reaction elements, each giving rise to a Ca2+ spark upon excitation. We imaged the spiral Ca2+ waves in isolated cardiac cells and numerically studied the effect of system excitability on spiral patterns using a two-dimensional fire-diffuse-fire model. We found that under certain conditions, the system was able to display multiple stable patterns of spiral waves, each exhibiting different periods and distinct routines of spiral tips. Transition between these different patterns could be triggered by an internal fluctuation in the form of a single Ca2+ spark. PMID:19792039

Transition of spiral calcium waves between multiple stable patterns can be triggered by a single calcium spark in a fire-diffuse-fire model.

Science.gov (United States)

Tang, Ai-Hui; Wang, Shi-Qiang

2009-09-01

Spiral patterns have been found in various nonequilibrium systems. The Ca(2+)-induced Ca(2+) release system in single cardiac cells is unique for highly discrete reaction elements, each giving rise to a Ca(2+) spark upon excitation. We imaged the spiral Ca(2+) waves in isolated cardiac cells and numerically studied the effect of system excitability on spiral patterns using a two-dimensional fire-diffuse-fire model. We found that under certain conditions, the system was able to display multiple stable patterns of spiral waves, each exhibiting different periods and distinct routines of spiral tips. Transition between these different patterns could be triggered by an internal fluctuation in the form of a single Ca(2+) spark.

Solution-phase synthesis of chromium-functionalized single-walled carbon nanotubes

KAUST Repository

Kalinina, Irina V.; Al-Hadeethi, Yas Fadel; Bekyarova, Elena; Zhao, Chao; Wang, Qingxiao; Zhang, Xixiang; Al-Zahrani, Ali; Al-Agel, Faisal Abdulaziz M; Al-Marzouki, Fahad M.; Haddon, Robert C.

2015-01-01

The solution phase reactions of single-walled carbon nanotubes (SWNTs) with Cr(CO)6 and benzene-Cr(CO)3 can lead to the formation of small chromium clusters. The cluster size can be varied from less than 1 nm to about 4 nm by increasing the reaction time. TEM images suggest that the clusters are deposited predominantly on the exterior walls of the nanotubes. TGA analysis was used to obtain the Cr content and carbon to chromium ratio in the Cr-complexed SWNTs. It is suggested that the carbon nanotube benzenoid structure templates the condensation of chromium atoms and facilitates the loss of carbon monoxide leading to well defined metal clusters.

Solution-phase synthesis of chromium-functionalized single-walled carbon nanotubes

KAUST Repository

Kalinina, Irina V.

2015-03-01

The solution phase reactions of single-walled carbon nanotubes (SWNTs) with Cr(CO)6 and benzene-Cr(CO)3 can lead to the formation of small chromium clusters. The cluster size can be varied from less than 1 nm to about 4 nm by increasing the reaction time. TEM images suggest that the clusters are deposited predominantly on the exterior walls of the nanotubes. TGA analysis was used to obtain the Cr content and carbon to chromium ratio in the Cr-complexed SWNTs. It is suggested that the carbon nanotube benzenoid structure templates the condensation of chromium atoms and facilitates the loss of carbon monoxide leading to well defined metal clusters.

Increasing amperometric biosensor sensitivity by length fractionated single-walled carbon nanotubes

DEFF Research Database (Denmark)

Tasca, Federico; Gorton, Lo; Wagner, Jakob Birkedal

2008-01-01

In this work the sensitivity-increasing effect of single-walled carbon nanotubes (SWCNTs) in amperometric biosensors, depending on their average length distribution, was studied. For this purpose the SWCNTs were oxidatively shortened and subsequently length separated by size exclusion...

A bench arc-furnace facility for fullerene and single-wall nanotubes synthesis

Directory of Open Access Journals (Sweden)

Huber John G

2001-01-01

Full Text Available A metallic-sample arc-furnace was modified to synthesize fullerenes and nanotubes. The (reversible changes and the process for producing single-wall nanotubes (SWNTs are described.

Dissociation of single-strand DNA: single-walled carbon nanotube hybrids by Watson-Crick base-pairing.

Science.gov (United States)

Jung, Seungwon; Cha, Misun; Park, Jiyong; Jeong, Namjo; Kim, Gunn; Park, Changwon; Ihm, Jisoon; Lee, Junghoon

2010-08-18

It has been known that single-strand DNA wraps around a single-walled carbon nanotube (SWNT) by pi-stacking. In this paper it is demonstrated that such DNA is dissociated from the SWNT by Watson-Crick base-pairing with a complementary sequence. Measurement of field effect transistor characteristics indicates a shift of the electrical properties as a result of this "unwrapping" event. We further confirm the suggested process through Raman spectroscopy and gel electrophoresis. Experimental results are verified in view of atomistic mechanisms with molecular dynamics simulations and binding energy analyses.

Evaluation of performance under fire of compressed earth blocks

OpenAIRE

Buson, M.; Lopes, N.; Varum, H.; Sposto, R. M.; Real, P. Vila

2012-01-01

In this paper are presented and discussed the main results of fire resistance tests on walls made of soil-cement and Kraftterra compressed earth blocks (CEB). Within this research it was intended to evaluate the fire resistance of walls made with CEB, with and without cellulose pulp incorporation deriving from recycling of cement sacks. Firstly, it is described the Kraftterra production processes and the fire resistance test campaign. Then, the performance of the blocks under anal...

Femtosecond laser ablation of single-wall carbon nanotube-based material

International Nuclear Information System (INIS)

Danilov, Pavel A; Ionin, Andrey A; Kudryashov, Sergey I; Makarov, Sergey V; Mel’nik, Nikolay N; Rudenko, Andrey A; Yurovskikh, Vladislav I; Zayarny, Dmitry V; Lednev, Vasily N; Obraztsova, Elena D; Pershin, Sergey M; Bunkin, Alexey F

2014-01-01

Single- and multi-shot femtosecond laser surface ablation of a single-wall carbon nanotube-based substrate at 515- and 1030 nm wavelengths was studied by scanning electron microscopy and micro-Raman spectroscopy. The laser ablation proceeds in two ways: as the low-fluence mesoscopic shallow disintegration of the surface nanotube packing, preserving the individual integrity and the semiconducting character of the nanotubes or as the high-fluence deep material removal apparently triggered by the strong intrinsic or impurity-mediated ablation of the individual carbon nanotubes on the substrate surface. (letter)

Nicotine adsorption on single wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Girao, Eduardo C. [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60455-900 Fortaleza, Ceara (Brazil); Fagan, Solange B.; Zanella, Ivana [Area de Ciencias Tecnologicas, Centro Universitario Franciscano - UNIFRA, 97010-032 Santa Maria, RS (Brazil); Filho, Antonio G. Souza, E-mail: agsf@fisica.ufc.br [Departamento de Fisica, Universidade Federal do Ceara, Caixa Postal 6030, Campus do Pici, 60455-900 Fortaleza, Ceara (Brazil)

2010-12-15

This work reports a theoretical study of nicotine molecules interacting with single wall carbon nanotubes (SWCNTs) through ab initio calculations within the framework of density functional theory (DFT). Different adsorption sites for nicotine on the surface of pristine and defective (8,0) SWCNTs were analyzed and the total energy curves, as a function of molecular position relative to the SWCNT surface, were evaluated. The nicotine adsorption process is found to be energetically favorable and the molecule-nanotube interaction is intermediated by the tri-coordinated nitrogen atom from the nicotine. It is also predicted the possibility of a chemical bonding between nicotine and SWCNT through the di-coordinated nitrogen.

Computer simulations of a generic truck cask in a regulatory fire using the Container Analysis Fire Environment (CAFE) code

International Nuclear Information System (INIS)

Ju, H.; Greiner, M.; Suo-Anttila, A.

2002-01-01

The Container Analysis Fire Environment (CAFE) computer code is designed to predict accurately convection and radiation heat transfer to a thermally massive object engulfed in a large pool fire. It is well suited for design and risk analyses of spent nuclear fuel transport systems. CAFE employs computational fluid dynamics and several fire and radiation models. These models must be benchmarked using experimental results. In this paper, a set of wind velocity conditions are determined which allow CAFE accurately to reproduce recent heat transfer measurements for a thick walled calorimeter in a ST-1 regulatory pool fire. CAFE is then used to predict the response of an intack (thin walled) generic legal weight truck cask. The maximum temperatures reached by internal components are within safe limits. A simple 800 deg. C, grey-radiation fire model gives maximum component temperatures that are somewhat below those predicted by CAFE. (author)

Fire-retardant-treated strandboard : properties and fire performance

Science.gov (United States)

Jerrold Winandy; Qingwen Wang; Robert H. White

2008-01-01

This study evaluated a series of single-layer, randomly oriented strandboard panels made with one resin type, a single resin loading level, and four fire-retardant-treatment levels. The fire retardant (FR) evaluated was a pH-buffered combination of boric acid and organic phosphate. Siberian larch strands were separated into five batches. One batch of strands served as...

Evolution of dispersion coefficient in the single rough-walled fracture before and after circulated flow near the wall

Science.gov (United States)

Lee, S.; Yeo, I.; Lee, K.

2012-12-01

Understanding detailed solute transport mechanism in a single fracture is required to expand it to the complex fractured medium. Dispersion in the variable-aperture fractures occurs by combined effects of molecular diffusion, macro dispersion and Taylor dispersion. It has been reported that Taylor dispersion which is proportional to the square of the velocity dominates for the high velocity, while macro dispersion is proportional to the velocity. Contributions of each scheme are different as the velocity changes. To investigate relationship between Reynolds number and dispersion coefficient, single acrylic rough-walled fracture which has 20 cm length and 1.03 mm average aperture was designed. In this experiment, dispersion coefficient was calculated at the middle of the fracture and at the edge of the fracture via moment analysis using breakthrough curve (BTC) of fluorescent solute under the Reynolds number 0.08, 0.28, 2.78, 8.2 and 16.4. In the results, distinct dispersion regime was observed at the highly rough-walled fracture, which is inconsistent with the model that was suggested by previous research. In the range of Re 2.78. The reason of this transition zone was related to the generation of circulated flow near the wall. It can flush the trapped contaminant out to the main flow channel, which makes tailing effect diminished. Also, these circulation zones were visualized using microscope, CCD camera and fluorescent particles.

Statistical Characterization of Dispersed Single-Wall Carbon Nanotube Quantum Dots

International Nuclear Information System (INIS)

Shimizu, M; Moriyama, S; Suzuki, M; Fuse, T; Homma, Y; Ishibashi, K

2006-01-01

Quantum dots have been fabricated in single-wall carbon nanotubes (SWCNTs) simply by depositing metallic contacts on top of them. The fabricated quantum dots show different characteristics from sample to sample, which are even different in samples fabricated in the same chip. In this report, we study the statistical variations of the quantum dots fabricated with our method, and suggest their possible origin

Production of vertical arrays of small diameter single-walled carbon nanotubes

Science.gov (United States)

Hauge, Robert H; Xu, Ya-Qiong

2013-08-13

A hot filament chemical vapor deposition method has been developed to grow at least one vertical single-walled carbon nanotube (SWNT). In general, various embodiments of the present invention disclose novel processes for growing and/or producing enhanced nanotube carpets with decreased diameters as compared to the prior art.

Evaluation of single-walled carbon nanohorns as sorbent in dispersive micro solid-phase extraction

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Soto, Juan Manuel; Cardenas, Soledad [Department of Analytical Chemistry, Institute of Fine Chemistry and Nanochemistry, Marie Curie Building, Campus de Rabanales, University of Cordoba, 14071 Cordoba (Spain); Valcarcel, Miguel, E-mail: qa1meobj@uco.es [Department of Analytical Chemistry, Institute of Fine Chemistry and Nanochemistry, Marie Curie Building, Campus de Rabanales, University of Cordoba, 14071 Cordoba (Spain)

2012-02-10

Highlights: Black-Right-Pointing-Pointer The potential of single walled carbon nanohorns in dispersive solid phase microextraction has been evaluated. Black-Right-Pointing-Pointer The method was characterized for the extraction of PAHs from waters. Black-Right-Pointing-Pointer Single walled carbon nanohorns were better extractant than carbon nanotubes and carbon nanocones. Black-Right-Pointing-Pointer The limits of detection were adequate for the target analytes in environmental waters. - Abstract: A new dispersive micro solid-phase extraction method which uses single-walled carbon nanohorns (SWNHs) as sorbent is proposed. The procedure combines the excellent sorbent properties of the nanoparticles with the efficiency of the dispersion of the material in the sample matrix. Under these conditions, the interaction with the analytes is maximized. The determination of polycyclic aromatic hydrocarbons was selected as model analytical problem. Two dispersion strategies were evaluated, being the functionalization via microwave irradiation better than the use of a surfactant. The extraction was accomplished by adding 1 mL of oxidized SWHNs (o-SWNHs) dispersion to 10 mL of water sample. After extraction, the mixture was passed through a disposable Nylon filter were the nanoparticles enriched with the PAHs were retained. The elution was carried out with 100 {mu}L of hexane. The limits of detection achieved were between 30 and 60 ng L{sup -1} with a precision (as repeatability) better than 12.5%. The recoveries obtained for the analytes in three different water samples were acceptable in all instances. The performance of o-SWNHs was favourably compared with that provided by carboxylated single-walled carbon nanotubes and thermally treated carbon nanocones.

Formation of transition metal cluster adducts on the surface of single-walled carbon nanotubes: HRTEM studies

KAUST Repository

Kalinina, Irina V.; Bekyarova, Elena B.; Wang, Qingxiao; Al-Hadeethi, Yas Fadel; Zhang, Xixiang; Al-Agel, Faisel; Al-Marzouki, Fahad M.; Yaghmour, Saud Jamil; Haddon, Robert C.

2014-01-01

We report the formation of chromium clusters on the outer walls of single-walled carbon nanotubes (SWNTs). The clusters were obtained by reacting purified SWNTs with chromium hexacarbonyl in dibutyl ether at 100°C. The functionalized SWNTs were

Ia Afferent input alters the recruitment thresholds and firing rates of single human motor units.

Science.gov (United States)

Grande, G; Cafarelli, E

2003-06-01

Vibration of the patellar tendon recruits motor units in the knee extensors via excitation of muscle spindles and subsequent Ia afferent input to the alpha-motoneuron pool. Our first purpose was to determine if the recruitment threshold and firing rate of the same motor unit differed when recruited involuntarily via reflex or voluntarily via descending spinal pathways. Although Ia input is excitatory to the alpha-motoneuron pool, it has also been shown paradoxically to inhibit itself. Our second purpose was to determine if vibration of the patellar tendon during a voluntary knee extension causes a change in the firing rate of already recruited motor units. In the first protocol, 10 subjects voluntarily reproduced the same isometric force profile of the knee extensors that was elicited by vibration of the patellar tendon. Single motor unit recordings from the vastus lateralis (VL) were obtained with tungsten microelectrodes and unitary behaviour was examined during both reflex and voluntary knee extensions. Recordings from 135 single motor units showed that both recruitment thresholds and firing rates were lower during reflex contractions. In the second protocol, 7 subjects maintained a voluntary knee extension at 30 N for approximately 40-45 s. Three bursts of patellar tendon vibration were superimposed at regular intervals throughout the contraction and changes in the firing rate of already recruited motor units were examined. A total of 35 motor units were recorded and each burst of superimposed vibration caused a momentary reduction in the firing rates and recruitment of additional units. Our data provide evidence that Ia input modulates the recruitment thresholds and firing rates of motor units providing more flexibility within the neuromuscular system to grade force at low levels of force production.

Single-walled carbon nanotubes as stabilizing agents in red phosphorus Li-ion battery anodes

KAUST Repository

Smajic, Jasmin

2017-08-16

Phosphorus boasts extremely high gravimetric and volumetric capacities but suffers from poor electrochemical stability with significant capacity loss immediately after the first cycle. We propose to circumvent this issue by mixing amorphous red phosphorus with single-walled carbon nanotubes. Employing a non-destructive sublimation–deposition method, we have synthesized composites where the synergetic effect between red phosphorus and single-walled carbon nanotubes allows for a considerable improvement in the electrochemical stability of battery anodes. In contrast to the average 40% loss of capacity after 50 cycles for other phosphorus–carbon composites in the literature, our material shows losses of just 22% under analogous cycling conditions.

Excitons in single-walled carbon nanotubes: environmental effect

International Nuclear Information System (INIS)

Smyrnov, O.A.

2010-01-01

The properties of excitons in semiconducting single-walled carbon nanotubes (SWCNTs) isolated in vacuum or a medium and their contributions to the optical spectra of nanotubes are studied within the elementary potential model, in which an exciton is represented as a bound state of two oppositely charged quasiparticles confined to the nanotube surface. The emphasis is given on the influence of the dielectric environment surrounding a nanotube on the exciton spectra. For nanotubes in the environment with a permittivity less than ∼ 1:8; the ground-state exciton binding energies exceed the respective energy gaps, whereas the obtained binding energies of excitons in nanotubes in a medium with permittivity greater than ∼ 4 are in good accordance with the corresponding experimental data and consistent with the known scaling relation for the environmental effect. The stabilization of a single-electron spectrum in SWCNTs in media with rather low permittivities is discussed.

Induced Magnetic Moment in Defected Single-Walled Carbon Nanotubes

International Nuclear Information System (INIS)

Liu Hong

2006-01-01

The existence of a large induced magnetic moment in defect single-walled carbon nanotube(SWNT) is predicted using the Green's function method. Specific to this magnetic moment of defect SWNT is its magnitude which is several orders of magnitude larger than that of perfect SWNT. The induced magnetic moment also shows certain remarkable features. Therefore, we suggest that two pair-defect orientations in SWNT can be distinguished in experiment through the direction of the induced magnetic moment at some Specific energy points

Small Scale Hydrocarbon Fire Test Concept

Directory of Open Access Journals (Sweden)

Joachim Søreng Bjørge

2017-11-01

Full Text Available In the oil and gas industry, hydrocarbon process equipment was previously often thermally insulated by applying insulation directly to the metal surface. Fire protective insulation was applied outside the thermal insulation. In some cases, severe corrosion attacks were observed due to ingress of humidity and condensation at cold surfaces. Introducing a 25 mm air gap to prevent wet thermal insulation and metal wall contact is expected to solve the corrosion issues. This improved insulation methodology does, however, require more space that may not be available when refurbishing older process plants. Relocating structural elements would introduce much hot work, which should be minimized in live plants. It is also costly. The aim of the present study is therefore to develop a test concept for testing fire resistance of equipment protected with only air-gap and thermal insulation, i.e., without the fire-protective insulation. The present work demonstrates a conceptual methodology for small scale fire testing of mockups resembling a section of a distillation column. The mockups were exposed to a small-scale propane flame in a test configuration where the flow rate and the flame zone were optimized to give heat flux levels in the range 250–350 kW/m2. Results are presented for a mockup resembling a 16 mm thick distillation column steel wall. It is demonstrated that the modern distance insulation in combination with the heat capacity of the column wall indicates 30+ minutes fire resistance. The results show that this methodology has great potentials for low cost fire testing of other configurations, and it may serve as a set-up for product development.

Efficient organometallic spin filter between single-wall carbon nanotube or graphene electrodes

DEFF Research Database (Denmark)

Koleini, Mohammad; Paulsson, Magnus; Brandbyge, Mads

2007-01-01

We present a theoretical study of spin transport in a class of molecular systems consisting of an organometallic benzene-vanadium cluster placed in between graphene or single-wall carbon-nanotube-model contacts. Ab initio modeling is performed by combining spin density functional theory...

Industrial-scale separation of high-purity single-chirality single-wall carbon nanotubes for biological imaging

Science.gov (United States)

Yomogida, Yohei; Tanaka, Takeshi; Zhang, Minfang; Yudasaka, Masako; Wei, Xiaojun; Kataura, Hiromichi

2016-01-01

Single-chirality, single-wall carbon nanotubes are desired due to their inherent physical properties and performance characteristics. Here, we demonstrate a chromatographic separation method based on a newly discovered chirality-selective affinity between carbon nanotubes and a gel containing a mixture of the surfactants. In this system, two different selectivities are found: chiral-angle selectivity and diameter selectivity. Since the chirality of nanotubes is determined by the chiral angle and diameter, combining these independent selectivities leads to high-resolution single-chirality separation with milligram-scale throughput and high purity. Furthermore, we present efficient vascular imaging of mice using separated single-chirality (9,4) nanotubes. Due to efficient absorption and emission, blood vessels can be recognized even with the use of ∼100-fold lower injected dose than the reported value for pristine nanotubes. Thus, 1 day of separation provides material for up to 15,000 imaging experiments, which is acceptable for industrial use. PMID:27350127

Chirality-Controlled Synthesis and Applications of Single-Wall Carbon Nanotubes.

Science.gov (United States)

Liu, Bilu; Wu, Fanqi; Gui, Hui; Zheng, Ming; Zhou, Chongwu

2017-01-24

Preparation of chirality-defined single-wall carbon nanotubes (SWCNTs) is the top challenge in the nanotube field. In recent years, great progress has been made toward preparing single-chirality SWCNTs through both direct controlled synthesis and postsynthesis separation approaches. Accordingly, the uses of single-chirality-dominated SWCNTs for various applications have emerged as a new front in nanotube research. In this Review, we review recent progress made in the chirality-controlled synthesis of SWCNTs, including metal-catalyst-free SWCNT cloning by vapor-phase epitaxy elongation of purified single-chirality nanotube seeds, chirality-specific growth of SWCNTs on bimetallic solid alloy catalysts, chirality-controlled synthesis of SWCNTs using bottom-up synthetic strategy from carbonaceous molecular end-cap precursors, etc. Recent major progresses in postsynthesis separation of single-chirality SWCNT species, as well as methods for chirality characterization of SWCNTs, are also highlighted. Moreover, we discuss some examples where single-chirality SWCNTs have shown clear advantages over SWCNTs with broad chirality distributions. We hope this review could inspire more research on the chirality-controlled preparation of SWCNTs and equally important inspire the use of single-chirality SWCNT samples for more fundamental studies and practical applications.

Optical transmission of nematic liquid crystal 5CB doped by single-walled and multi-walled carbon nanotubes.

Science.gov (United States)

Lisetski, L N; Fedoryako, A P; Samoilov, A N; Minenko, S S; Soskin, M S; Lebovka, N I

2014-08-01

Comparative studies of optical transmission of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs), dispersed in nematic liquid crystal matrix 5CB, were carried out. The data evidence violations of Beer-Lambert-Bouguer (BLB) law both in cell thickness and concentration dependencies. The most striking is the fact that optical transmission dependencies for SWCNTs and MWCNTs were quite different in the nematic phase, but they were practically indistinguishable in the isotropic phase. Monte Carlo simulations of the impact of aggregation on direct transmission and violation of BLB law were also done. The results were discussed accounting for the tortuous shape of CNTs, their physical properties and aggregation, as well as strong impact of perturbations of the nematic 5CB structure inside coils and in the vicinity of CNT aggregates.

Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

DEFF Research Database (Denmark)

He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

2012-01-01

Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type...... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution....

Electronic properties of pristine and modified single-walled carbon nanotubes

International Nuclear Information System (INIS)

Kharlamova, M V

2013-01-01

The current status of research on the electronic properties of filled single-walled carbon nanotubes (SWCNTs) is reviewed. SWCNT atomic structure and electronic properties are described, and their correlation is discussed. Methods for modifying the electronic properties of SWCNTs are considered. SWCNT filling materials are systematized. Experimental and theoretical data on the electronic properties of filled SWCNTs are analyzed. Possible application areas for filled SWCNTs are explored. (reviews of topical problems)

Experimental study of fire barriers preventing vertical fire spread in ETISs

Directory of Open Access Journals (Sweden)

Xin Huang

2013-11-01

Full Text Available In recent years, the external thermal insulation system (ETIS has been applied increasingly in a large amount of buildings for energy conservation purpose. However, the increase use of combustible insulation materials in the ETIS has raised serious fire safety problems. Fires involving this type of ETIS have caused severe damage and loss. In order to improve its fire safety, fire barriers were suggested to be installed. This paper introduces fire experiments that have been done to study the effects of fire barriers on preventing vertical fire spread along the ETIS. The experiments were performed according to BS 8414-1:2002 “Fire performance of external cladding systems – Part 1: Test method for non-loadbearing external cladding systems applied to the face of the building”. The test facility consists of a 9 m high wall. The fire sources were wood cribs with a fire size of 3 ± 0.5 MW. The insulation materials were expanded polystyrene foam (EPS. The fire barrier was a horizontal strip of rockwool with a width of 300 mm. Thermocouples were used to measure temperatures outside and inside the ETIS. A series of experiments with different fire scenarios were done: no fire barrier, two fire barriers and three fire barriers at different heights. Test results were compared. The results show that the ETIS using EPS without fire barriers almost burned out, while the ETIS with fire barriers performed well in preventing fire spread. The temperatures above the fire barrier were much lower than those below the fire barrier, and most of the insulation materials above the top fire barrier stayed in place.

Single-Walled Carbon Nanotubes in Solar Cells.

Science.gov (United States)

Jeon, Il; Matsuo, Yutaka; Maruyama, Shigeo

2018-01-22

Photovoltaics, more generally known as solar cells, are made from semiconducting materials that convert light into electricity. Solar cells have received much attention in recent years due to their promise as clean and efficient light-harvesting devices. Single-walled carbon nanotubes (SWNTs) could play a crucial role in these devices and have been the subject of much research, which continues to this day. SWNTs are known to outperform multi-walled carbon nanotubes (MWNTs) at low densities, because of the difference in their optical transmittance for the same current density, which is the most important parameter in comparing SWNTs and MWNTs. SWNT films show semiconducting features, which make SWNTs function as active or charge-transporting materials. This chapter, consisting of two sections, focuses on the use of SWNTs in solar cells. In the first section, we discuss SWNTs as a light harvester and charge transporter in the photoactive layer, which are reviewed chronologically to show the history of the research progress. In the second section, we discuss SWNTs as a transparent conductive layer outside of the photoactive layer, which is relatively more actively researched. This section introduces SWNT applications in silicon solar cells, organic solar cells, and perovskite solar cells each, from their prototypes to recent results. As we go along, the science and prospects of the application of solar cells will be discussed.

Symmetry Properties of Single-Walled BC2N Nanotubes

Directory of Open Access Journals (Sweden)

Lin Jianyi

2009-01-01

Full Text Available Abstract The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

Center for Applications of Single-Walled Carbon Nanotubes

Energy Technology Data Exchange (ETDEWEB)

Resasco, Daniel E

2008-02-21

This report describes the activities conducted under a Congressional Direction project whose goal was to develop applications for Single-walled carbon nanotubes, under the Carbon Nanotube Technology Center (CANTEC), a multi-investigator program that capitalizes on OU’s advantageous position of having available high quality carbon nanotubes. During the first phase of CANTEC, 11 faculty members and their students from the College of Engineering developed applications for carbon nanotubes by applying their expertise in a number of areas: Catalysis, Reaction Engineering, Nanotube synthesis, Surfactants, Colloid Chemistry, Polymer Chemistry, Spectroscopy, Tissue Engineering, Biosensors, Biochemical Engineering, Cell Biology, Thermal Transport, Composite Materials, Protein synthesis and purification, Molecular Modeling, Computational Simulations. In particular, during this phase, the different research groups involved in CANTEC made advances in the tailoring of Single-Walled Carbon Nanotubes (SWNT) of controlled diameter and chirality by Modifying Reaction Conditions and the Nature of the catalyst; developed kinetic models that quantitatively describe the SWNT growth, created vertically oriented forests of SWNT by varying the density of metal nanoparticles catalyst particles, and developed novel nanostructured SWNT towers that exhibit superhydrophobic behavior. They also developed molecular simulations of the growth of Metal Nanoparticles on the surface of SWNT, which may have applications in the field of fuell cells. In the area of biomedical applications, CANTEC researchers fabricated SWNT Biosensors by a novel electrostatic layer-by-layer (LBL) deposition method, which may have an impact in the control of diabetes. They also functionalized SWNT with proteins that retained the protein’s biological activity and also retained the near-infrared light absorbance, which finds applications in the treatment of cancer.

Length-dependent optical properties of single-walled carbon nanotube samples

International Nuclear Information System (INIS)

Naumov, Anton V.; Tsyboulski, Dmitri A.; Bachilo, Sergei M.; Weisman, R. Bruce

2013-01-01

Highlights: ► Length-independent absorption per atom in single-walled carbon nanotubes. ► Reduced fluorescence quantum yield for short nanotubes. ► Exciton quenching at nanotube ends, sidewall defects probably limits quantum yield. - Abstract: Contradictory findings have been reported on the length dependence of optical absorption cross sections and fluorescence quantum yields in single-walled carbon nanotubes (SWCNTs). To clarify these points, studies have been made on bulk SWCNT dispersions subjected to length fractionation by electrophoretic separation or by ultrasonication-induced scission. Fractions ranged from ca. 120 to 760 nm in mean length. Samples prepared by shear-assisted dispersion were subsequently shortened by ultrasonic processing. After accounting for processing-induced changes in the surfactant absorption background, SWCNT absorption was found constant within ±11% as average nanotube length changed by a factor of 3.8. This indicates that the absorption cross-section per carbon atom is not length dependent. By contrast, in length fractions prepared by both methods, the bulk fluorescence efficiency or average quantum yield increased with SWCNT average length and approached an apparent asymptotic limit near 1 μm. This result is interpreted as reflecting the combined contributions of exciton quenching by sidewall defects and by the ends of shorter nanotubes

Holden gas-fired furnace baseline data. Revision 1

International Nuclear Information System (INIS)

Weatherspoon, K.A.

1996-11-01

The Holden gas-fired furnace is used in the enriched uranium recovery process to dry and combust small batches of combustibles. The ash is further processed. The furnace operates by allowing a short natural gas flame to burn over the face of a wall of porous fire brick on two sides of the furnace. Each firing wall uses two main burners and a pilot burner to heat the porous fire brick to a luminous glow. Regulators and orifice valves are used to provide a minimum gas pressure of 4 in. water column at a rate of approximately 1,450 scf/h to the burners. The gas flow rate was calculated by determining the gas flow appropriate for the instrumentation in the gas line. Observed flame length and vendor literature were used to calculate pilot burner gas consumption. Air for combustion, purging, and cooling is supplied by a single blower. Rough calculations of the air-flow distribution in piping entering the furnace show that air flow to the burners approximately agrees with the calculated natural gas flow. A simple on/off control loop is used to maintain a temperature of 1,000 F in the furnace chamber. Hoods and glove boxes provide contamination control during furnace loading and unloading and ash handling. Fan EF-120 exhausts the hoods, glove boxes, and furnace through filters to Stack 33. A review of the furnace safety shows that safety is ensured by design, interlocks, procedure, and a safety system. Recommendations for safety improvements include installation of both a timed ignition system and a combustible-gas monitor near the furnace. Contamination control in the area could be improved by redesigning the loading hood face and replacing worn gaskets throughout the system. 33 refs., 16 figs

Innovative clean coal technology: 500 MW demonstration of advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NOx) emissions from coal-fired boilers. Final report, Phases 1 - 3B

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-01-01

This report presents the results of a U.S. Department of Energy (DOE) Innovative Clean Coal Technology (ICCT) project demonstrating advanced wall-fired combustion techniques for the reduction of nitrogen oxide (NOx) emissions from coal-fired boilers. The project was conducted at Georgia Power Company`s Plant Hammond Unit 4 located near Rome, Georgia. The technologies demonstrated at this site include Foster Wheeler Energy Corporation`s advanced overfire air system and Controlled Flow/Split Flame low NOx burner. The primary objective of the demonstration at Hammond Unit 4 was to determine the long-term effects of commercially available wall-fired low NOx combustion technologies on NOx emissions and boiler performance. Short-term tests of each technology were also performed to provide engineering information about emissions and performance trends. A target of achieving fifty percent NOx reduction using combustion modifications was established for the project. Short-term and long-term baseline testing was conducted in an {open_quotes}as-found{close_quotes} condition from November 1989 through March 1990. Following retrofit of the AOFA system during a four-week outage in spring 1990, the AOFA configuration was tested from August 1990 through March 1991. The FWEC CF/SF low NOx burners were then installed during a seven-week outage starting on March 8, 1991 and continuing to May 5, 1991. Following optimization of the LNBs and ancillary combustion equipment by FWEC personnel, LNB testing commenced during July 1991 and continued until January 1992. Testing in the LNB+AOFA configuration was completed during August 1993. This report provides documentation on the design criteria used in the performance of this project as it pertains to the scope involved with the low NOx burners and advanced overfire systems.

Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes

International Nuclear Information System (INIS)

Jang, Sukjae; Jang, Houk; Lee, Youngbin; Suh, Daewoo; Baik, Seunghyun; Hong, Byung Hee; Ahn, Jong-Hyun

2010-01-01

This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of ∼ 2 cm 2 V -1 s -1 , On/Off ratio of ∼ 10 2 , transmittance of ∼ 81% and excellent mechanical bendability.

Fire test database

International Nuclear Information System (INIS)

Lee, J.A.

1989-01-01

This paper describes a project recently completed for EPRI by Impell. The purpose of the project was to develop a reference database of fire tests performed on non-typical fire rated assemblies. The database is designed for use by utility fire protection engineers to locate test reports for power plant fire rated assemblies. As utilities prepare to respond to Information Notice 88-04, the database will identify utilities, vendors or manufacturers who have specific fire test data. The database contains fire test report summaries for 729 tested configurations. For each summary, a contact is identified from whom a copy of the complete fire test report can be obtained. Five types of configurations are included: doors, dampers, seals, wraps and walls. The database is computerized. One version for IBM; one for Mac. Each database is accessed through user-friendly software which allows adding, deleting, browsing, etc. through the database. There are five major database files. One each for the five types of tested configurations. The contents of each provides significant information regarding the test method and the physical attributes of the tested configuration. 3 figs

Spray deposition of steam treated and functionalized single-walled and multi-walled carbon nanotube films for supercapacitors

International Nuclear Information System (INIS)

Zhao Xin; Chu, Bryan T T; Johnston, Colin; Sykes, John M; Grant, Patrick S; Ballesteros, Belen; Wang Weiliang

2009-01-01

Steam purified, carboxylic and ester functionalized single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) films with homogeneous distribution and flexible control of thickness and area were fabricated on polymeric and metallic substrates using a modified spray deposition technique. By employing a pre-sprayed polyelectrolyte, the adhesion of the carbon nanotube (CNT) films to the substrates was significantly enhanced by electrostatic interaction. Carboxylic and ester functionalization improved electrochemical performance when immersed in 0.1 M H 2 SO 4 and the specific capacitance reached 155 and 77 F g -1 for carboxylic functionalized SWNT and MWNT films respectively. Compared with existing techniques such as hot pressing, vacuum filtration and dip coating, the ambient pressure spray deposition technique is suggested as particularly well suited for preparing CNT films at large scale for applications including providing electrodes for electrochemical supercapacitors and paper batteries.

Free vibration analysis of single-walled boron nitride nanotubes based on a computational mechanics framework

Science.gov (United States)

Yan, J. W.; Tong, L. H.; Xiang, Ping

2017-12-01

Free vibration behaviors of single-walled boron nitride nanotubes are investigated using a computational mechanics approach. Tersoff-Brenner potential is used to reflect atomic interaction between boron and nitrogen atoms. The higher-order Cauchy-Born rule is employed to establish the constitutive relationship for single-walled boron nitride nanotubes on the basis of higher-order gradient continuum theory. It bridges the gaps between the nanoscale lattice structures with a continuum body. A mesh-free modeling framework is constructed, using the moving Kriging interpolation which automatically satisfies the higher-order continuity, to implement numerical simulation in order to match the higher-order constitutive model. In comparison with conventional atomistic simulation methods, the established atomistic-continuum multi-scale approach possesses advantages in tackling atomic structures with high-accuracy and high-efficiency. Free vibration characteristics of single-walled boron nitride nanotubes with different boundary conditions, tube chiralities, lengths and radii are examined in case studies. In this research, it is pointed out that a critical radius exists for the evaluation of fundamental vibration frequencies of boron nitride nanotubes; opposite trends can be observed prior to and beyond the critical radius. Simulation results are presented and discussed.

Excitons in Single-Walled Carbon Nanotubes and Their Dynamics

Science.gov (United States)

Amori, Amanda R.; Hou, Zhentao; Krauss, Todd D.

2018-04-01

Understanding exciton dynamics in single-walled carbon nanotubes (SWCNTs) is essential to unlocking the many potential applications of these materials. This review summarizes recent progress in understanding exciton photophysics and, in particular, exciton dynamics in SWCNTs. We outline the basic physical and electronic properties of SWCNTs, as well as bright and dark transitions within the framework of a strongly bound one-dimensional excitonic model. We discuss the many facets of ultrafast carrier dynamics in SWCNTs, including both single-exciton states (bright and dark) and multiple-exciton states. Photophysical properties that directly relate to excitons and their dynamics, including exciton diffusion lengths, chemical and structural defects, environmental effects, and photoluminescence photon statistics as observed through photon antibunching measurements, are also discussed. Finally, we identify a few key areas for advancing further research in the field of SWCNT excitons and photonics.

Photonic density of states in the vicinity of a single-wall finite-length carbon nanotube

International Nuclear Information System (INIS)

Nemilentsau, A; Ya Slepyan, G; Maksimenko, S A

2009-01-01

Photonic density of states in the vicinity of a single-wall finite-length carbon nanotube (CNT) is investigated theoretically in this paper. The analysis is based on the fluctuation-dissipative theorem in the Callen-Welton form. The Dyson equation for the Green dyadic of the electromagnetic field in the presence of CNT is formulated and a method for its numerical solution is elaborated. We show that the photonic density of states spectrum has a nontrivial resonant structure in the terahertz range in the vicinity of the metallic single-wall CNT. The origin of these resonances is the surface plasmon resonances on the CNT's edges.

Monitoring the functionalization of single-walled carbon nanotubes with chitosan and folic acid by two-dimensional diffusion-ordered nmr spectroscopy

DEFF Research Database (Denmark)

Castillo, John J.; Torres, Mary H.; Molina, Daniel R.

2012-01-01

A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate that was......A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate...... that was generated by the linkage between the carboxyl moiety of the folic acid and the amino group of the chitosan, which in turn was non-covalently bound to the single-walled carbon nanotubes. The obtained diffusion coefficient values demonstrated that free folic acid diffused more rapidly than the folic acid...... conjugated to single-walled carbon nanotubes-chitosan. The values of the proton signal of hydrogen-1 nuclear magnetic resonance spectroscopy and two-dimensional hydrogen-1 nuclear magnetic resonance spectroscopy further confirmed that the folic acid was conjugated to the chitosan, wrapping the single...

Ultrafast excitation energy transfer from encapsulated quaterrylene to single-walled carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Koyama, Takeshi, E-mail: koyama@nuap.nagoya-u.ac.jp [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Tsunekawa, Takuya [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Saito, Takeshi [Research Center for Advanced Carbon Materials, AIST, Tsukuba, Ibaraki 305-8565 (Japan); Asaka, Koji; Saito, Yahachi [Department of Quantum Engineering, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Kishida, Hideo [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Nakamura, Arao [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Toyota Physical and Chemical Research Institute, Nagakute, Aichi 480-1192 (Japan)

2016-01-15

We investigate excitation energy transfer from an encapsulated quaterrylene molecule to a single-walled carbon nanotube by means of femtosecond pump-probe spectroscopy. The time constant of energy transfer becomes shorter with increasing average diameter of nanotube: 1.4±0.2 ps for 1.0 nm, 1.1±0.2 ps for 1.4 nm, and 0.4±0.1 ps for 1.8 nm. The observed behavior is discussed considering the distance of less than 1 nm between the molecule and the nanotube wall. - Highlights: • Dynamical properties of excited states in quaterrylene/SWNT composites were studied. • Excitation energy transfer occurs in the time range of 0.4-1.4 ps. • The transfer rate depends on the nanotube diameter, i.e. molecule-nanotube wall distance. • This dependence indicates the feature of excitation energy transfer on the nanoscale.

Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope

National Research Council Canada - National Science Library

Lee, Haiwon

2007-01-01

This project focused on the behavior of single-wall carbon nanotubes (SWCNTs) in the electrophoresis cells and aligned growth of SWCNTs by thermal chemical vapor deposition on selectively deposited metallic nanoparticle...

Large-scale single-chirality separation of single-wall carbon nanotubes by simple gel chromatography

Science.gov (United States)

Liu, Huaping; Nishide, Daisuke; Tanaka, Takeshi; Kataura, Hiromichi

2011-01-01

Monostructured single-wall carbon nanotubes (SWCNTs) are important in both scientific research and electronic and biomedical applications; however, the bulk separation of SWCNTs into populations of single-chirality nanotubes remains challenging. Here we report a simple and effective method for the large-scale chirality separation of SWCNTs using a single-surfactant multicolumn gel chromatography method utilizing one surfactant and a series of vertically connected gel columns. This method is based on the structure-dependent interaction strength of SWCNTs with an allyl dextran-based gel. Overloading an SWCNT dispersion on the top column results in the adsorption sites of the column becoming fully occupied by the nanotubes that exhibit the strongest interaction with the gel. The unbound nanotubes flow through to the next column, and the nanotubes with the second strongest interaction with the gel are adsorbed in this stage. In this manner, 13 different (n, m) species were separated. Metallic SWCNTs were finally collected as unbound nanotubes because they exhibited the lowest interaction with the gel. PMID:21556063

Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes

Energy Technology Data Exchange (ETDEWEB)

Jang, Sukjae; Jang, Houk; Lee, Youngbin; Suh, Daewoo; Baik, Seunghyun; Hong, Byung Hee; Ahn, Jong-Hyun, E-mail: ahnj@skku.edu, E-mail: byunghee@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

2010-10-22

This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of {approx} 2 cm{sup 2} V{sup -1} s{sup -1}, On/Off ratio of {approx} 10{sup 2}, transmittance of {approx} 81% and excellent mechanical bendability.

Alignment characterization of single-wall carbon nanotubes by Raman scattering

International Nuclear Information System (INIS)

Liu Pijun; Liu Liyue; Zhang Yafei

2003-01-01

A novel method for identifying the Raman modes of single-wall carbon nanotubes (SWNT) based on the symmetry of the vibration modes has been studied. The Raman intensity of each vibration mode varies with polarization direction, and the relationship can be expressed as analytical functions. This method avoids troublesome numerical calculation and easily gives clear relations between Raman intensity and polarization direction. In this way, one can distinguish each Raman-active mode of SWNT through the polarized Raman spectrum

Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties

Directory of Open Access Journals (Sweden)

Shayesteh eHaghighatpanah

2014-09-01

Full Text Available Molecular dynamics and molecular mechanics methods have been used to investigate additive-polymer interfacial properties in single walled carbon nanotube – polyethylene and single walled carbon nanotube – polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the single walled carbon nanotubes with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1% to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the single walled carbon nanotube wall.

One-dimensional flame instability and control of burning in fire-chamber

Directory of Open Access Journals (Sweden)

Victor E. Volkov

2015-03-01

Full Text Available The flame stability with regard to one-dimensional exponential perturbations both for the combustion in the fire-chamber and the flame propagating in closed tubes or chambers is investigated. It is proved that both stability and instability are possible for the combustion process. At the same time the one-dimensional flame instability is guaranteed near the front wall of the fire-chamber where the fuel supply is realized. Therefore the control of combustion in the fire-chamber leads to support of the flame at the maximum possible distance from the front wall of the fire-chamber to prevent the vibratory combustion or to diminish intensity of pulsations if these pulsations are inevitable.

Fluorescent single walled nanotube/silica composite materials

Science.gov (United States)

Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.

2013-03-12

Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.

Vertical single- and double-walled carbon nanotubes grown from modified porous anodic alumina templates

International Nuclear Information System (INIS)

Maschmann, Matthew R; Franklin, Aaron D; Amama, Placidus B; Zakharov, Dmitri N; Stach, Eric A; Sands, Timothy D; Fisher, Timothy S

2006-01-01

Vertical single-walled and double-walled carbon nanotube (SWNT and DWNT) arrays have been grown using a catalyst embedded within the pore walls of a porous anodic alumina (PAA) template. The initial film structure consisted of a SiO x adhesion layer, a Ti layer, a bottom Al layer, a Fe layer, and a top Al layer deposited on a Si wafer. The Al and Fe layers were subsequently anodized to create a vertically oriented pore structure through the film stack. CNTs were synthesized from the catalyst layer by plasma-enhanced chemical vapour deposition (PECVD). The resulting structure is expected to form the basis for development of vertically oriented CNT-based electronics and sensors

Proposal of a Self-baking Single-wall Design for the VI Section of the ATLAS Beam Pipe

CERN Document Server

Marco Olcese, MO

2002-01-01

A single-wall design for the VI section of the ATLAS beam vacuum chamber is presented. This design would allow for a major cost saving with respect to the current double-wall baseline. All the thermal implications and impact on the B-layer mudules are discussed.

Non-radiative Exciton Decay in Single-walled Carbon Nanotubes

Science.gov (United States)

Harrah, Mark; Swan, Anna

2010-03-01

Experiments have shown step-wise changes in the fluorescence intensity from single-walled carbon nanotubes [1,2]. It has been proposed that the underlying mechanism for the step-wise changes is diffusion-limited quenching of excitons at defects [1]. This property has been used to demonstrate single-molecule detection for biological applications [3]. We perform a Monte-Carlo simulation of nanotube fluorescence with a diffusion-limited quenching model. The fluorescence intensity is seen to depend on the mean-square distance between defects, implying a nonlinear dependence on the number of defects. The intensity for consecutive defect counts can overlap depending on the positions of the defects. [4pt] [1] Cognet, L. et al. Science 316, 1465-1468 (2007).[0pt] [2] Jin, H. et al. Nano Lett. 8, 4299-4304 (2008).[0pt] [3] Heller, D. A. et al. Nature Nanotech. 4, 114-120 (2009).

Comparison of the characteristics of fire and non-fire households in the 2004-2005 survey of fire department-attended and unattended fires.

Science.gov (United States)

Greene, Michael A

2012-06-01

Comparison of characteristics of fire with non-fire households to determine factors differentially associated with fire households (fire risk factors). National household telephone survey in 2004-2005 by the US Consumer Product Safety Commission with 916 fire households and a comparison sample of 2161 non-fire households. There were an estimated 7.4 million fires (96.6% not reported to fire departments) with 130,000 injuries. Bivariate analysis and multivariate logistic regression analyses to assess differences in household characteristics. Significant factors associated with fire households were renting vs. owning (OR 1.988 pfire households with non-cooking fires (OR 1.383 p=0.0011). Single family houses were associated with non-fire households in the bivariate analysis but not in the multivariate analyses. Renting, household members under 18 years old and smokers are risk factors for unattended fires, similar to the literature for fatal and injury fires. Differences included household members over 65 years old (associated with non-fire households), college/postgraduate education (associated with fire households) and lack of significance of income. Preventing cooking fires (64% of survey incidents), smoking prevention efforts and fire prevention education for families with young children have the potential for reducing unattended fires and injuries.

Critical firing and misfiring boundary in a spark ignition methanol engine during cold start based on single cycle fuel injection

International Nuclear Information System (INIS)

Li, Zhaohui; Gong, Changming; Qu, Xiang; Liu, Fenghua; Sun, Jingzhen; Wang, Kang; Li, Yufeng

2015-01-01

The influence of the mass of methanol injected per cycle, ambient temperature, injection and ignition timing, preheating methods, and supplying additional liquefied petroleum gas (LPG) injection into the intake manifold on the critical firing and misfiring boundary of an electronically injection controlled spark ignition (SI) methanol engine during cold start were investigated experimentally based on a single cycle fuel injection with cycle-by-cycle control strategy. The critical firing and misfiring boundary was restricted by all parameters. For ambient temperatures below 16 °C, methanol engines must use auxiliary start-aids during cold start. Optimal control of the methanol injection and ignition timing can realize ideal next cycle firing combustion after injection. Resistance wire and glow plug preheating can provide critical firing down to ambient temperatures of 5 °C and 0 °C, respectively. Using an additional LPG injection into the intake manifold can provide critical firing down to an ambient temperature of −13 °C during cold start. As the ambient temperature decreases, the optimal angle difference between methanol injection timing and LPG injection timing for critical firing of a methanol engine increases rapidly during cold start. - Highlights: • A single cycle fuel injection and cycle-by-cycle control strategy are used to study. • In-cylinder pressure and instantaneous speed were used to determine firing boundary. • For the ambient temperatures below 16 °C, an auxiliary start-aids must be used. • A preheating and additional LPG were used to expand critical firing boundary. • Additional LPG can result in critical firing down to ambient temperature of −13 °C

Hot wire production of single-wall and multi-wall carbon nanotubes

Science.gov (United States)

Dillon, Anne C.; Mahan, Archie H.; Alleman, Jeffrey L.

2010-10-26

Apparatus (210) for producing a multi-wall carbon nanotube (213) may comprise a process chamber (216), a furnace (217) operatively associated with the process chamber (216), and at least one filament (218) positioned within the process chamber (216). At least one power supply (220) operatively associated with the at least one filament (218) heats the at least one filament (218) to a process temperature. A gaseous carbon precursor material (214) operatively associated with the process chamber (216) provides carbon for forming the multi-wall carbon nanotube (213). A metal catalyst material (224) operatively associated with the process (216) catalyzes the formation of the multi-wall carbon nanotube (213).

Analysis of sodium pool fire in SFEF for assessing the limiting pool fire

International Nuclear Information System (INIS)

Mangarjuna Rao, P.; Ramesh, S.S.; Nashine, B.K.; Kasinathan, N.; Chellapandi, P.

2011-01-01

Accidental sodium leaks and resultant sodium fires in Liquid Metal Fast Breeder Reactor (LMFBR) systems can create a threat to the safe operation of the plant. To avoid this defence-in depth approach is implemented from the design stage of reactor itself. Rapid detection of sodium leak and fast dumping of the sodium into the storage tank of a defective circuit, leak collection trays, adequate lining of load bearing structural concrete and extinguishment of the sodium fire are the important defensive measures in the design, construction and operation of a LMFBR for protection against sodium leaks and their resultant fires. Evaluation of sodium leak events and their consequences by conducting large scale engineering experiments is very essential for effective implementation of the above protection measures for sodium fire safety. For this purpose a Sodium Fire Experimental Facility (SFEF) is constructed at SED, IGCAR. SFEF is having an experimental hall of size 9 m x 6 m x 10 m with 540 m 3 volume and its design pressure is 50 kPa. It is a concrete structure and provided with SS 304 liner, which is fixed to the inside surfaces of walls, ceiling and floor. A leak tight door of size (1.8 m x 2.0 m) is provided to the experimental hall and the facility is provided with a sodium equipment hall and a control room. Experimental evaluation of sodium pool fire consequences is an important activity in the LMFBR sodium fire safety related studies. An experimental program has been planned for different types of sodium fire studies in SFEF. A prior to that numerical analysis have been carried out for enclosed sodium pool fires using SOFIRE-II sodium pool fire code for SFEF experimental hall configuration to evaluate the limiting pool fire. This paper brings out results of the analysis carried out for this purpose. Limiting pool fire of SFEF depends on the exposed surface area of the pool, amount of sodium in the pool, oxygen concentration and initial sodium temperature. Limiting

Comparison of 4-chloro-2-nitrophenol adsorption on single-walled and multi-walled carbon nanotubes

Directory of Open Access Journals (Sweden)

Mehrizad Ali

2012-09-01

Full Text Available Abstract The adsorption characteristics of 4-chloro-2-nitrophenol (4C2NP onto single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs from aqueous solution were investigated with respect to the changes in the contact time, pH of solution, carbon nanotubes dosage and initial 4C2NP concentration. Experimental results showed that the adsorption efficiency of 4C2NP by carbon nanotubes (both of SWCNTs and MWCNTs increased with increasing the initial 4C2NP concentration. The maximum adsorption took place in the pH range of 2–6. The linear correlation coefficients of different isotherm models were obtained. Results revealed that the Langmuir isotherm fitted the experimental data better than the others and based on the Langmuir model equation, maximum adsorption capacity of 4C2NP onto SWCNTs and MWCNTs were 1.44 and 4.42 mg/g, respectively. The observed changes in the standard Gibbs free energy, standard enthalpy and standard entropy showed that the adsorption of 4C2NP onto SWCNTs and MWCNTs is spontaneous and exothermic in the temperature range of 298–328 K.

Structure and Characterization of Vertically Aligned Single-Walled Carbon Nanotube Bundles

International Nuclear Information System (INIS)

Marquez, F.; Morant, C.; Elizalde, E.; Roque-Malherbe, R.; Lopez, V.; Zamora, F.; Domingo, C.

2010-01-01

Arrays of vertically aligned single-walled carbon nanotube bundles, SWCNTs, have been synthesized by simple alcohol catalytic chemical vapor deposition process, carried out at 800 degree C. The formed SWCNTs are organized in small groups perpendicularly aligned and attached to the substrate. These small bundles show a constant diameter of ca. 30 nm and are formed by the adhesion of no more than twenty individual SWCNTs perfectly aligned along their length.

Hydrostatic-pressure induced phase transition of phonons in single-walled nanotubes

International Nuclear Information System (INIS)

Feng Peng; Meng Qingchao

2009-01-01

We study the effect of the hydrostatic pressure on the phonons in single-walled carbon nanotubes (SWNTs) in a magnetic field. We calculate the magnetic moments of the phonons using a functional integral technique, and find that the phonons in SWNTs undergo a pressure-induced phase transition from the paramagnetic phase to the diamagnetic phase under hydrostatic pressure 2 GPa. We explain the mechanism of generating this phase transition.

Phototransformation-Induced Aggregation of Functionalized Single-Walled Carbon Nanotubes: The Importance of Amorphous Carbon

Science.gov (United States)

Single-walled carbon nanotubes (SWCNTs) with proper functionalization are desirable for applications that require dispersion in aqueous and biological environments, and functionalized SWCNTs also serve as building blocks for conjugation with specific molecules in these applicatio...

Sensitivity Analysis on Fire Modeling of Main Control Board Fire Using Fire Dynamics Simulator

International Nuclear Information System (INIS)

Kang, Dae Il; Lim, Ho Gon

2015-01-01

In this study, sensitivity analyses for an MCB fire were performed to identify the effects on the MCR forced abandonment time according to the changes of height and number for fire initiation places. Hanul Unit 3 NPP was selected as a reference plant for this study. In this study, sensitivity analyses for an MCB fire were performed to identify the effects on the MCR forced abandonment time according to the changes of height and number of fire initiation places. A main control board (MCB) fire can cause a forced main control room (MCR) abandonment of the operators as well as the function failures or spurious operations of the control and instrumentation-related components. If the MCR cannot be habitable, a safe shutdown from outside the MCR can be achieved and maintained at an alternate shutdown panel independent from the MCR. When the fire modeling for an electrical cabinet such as an MCB was performed, its many input parameters can affect the fire simulation results. This study results showed that the decrease in the height of fire ignition place and the use of single fire ignition place in fire modeling for the propagating fire shortened MCR abandonment time

Sensitivity Analysis on Fire Modeling of Main Control Board Fire Using Fire Dynamics Simulator

Energy Technology Data Exchange (ETDEWEB)

Kang, Dae Il; Lim, Ho Gon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

In this study, sensitivity analyses for an MCB fire were performed to identify the effects on the MCR forced abandonment time according to the changes of height and number for fire initiation places. Hanul Unit 3 NPP was selected as a reference plant for this study. In this study, sensitivity analyses for an MCB fire were performed to identify the effects on the MCR forced abandonment time according to the changes of height and number of fire initiation places. A main control board (MCB) fire can cause a forced main control room (MCR) abandonment of the operators as well as the function failures or spurious operations of the control and instrumentation-related components. If the MCR cannot be habitable, a safe shutdown from outside the MCR can be achieved and maintained at an alternate shutdown panel independent from the MCR. When the fire modeling for an electrical cabinet such as an MCB was performed, its many input parameters can affect the fire simulation results. This study results showed that the decrease in the height of fire ignition place and the use of single fire ignition place in fire modeling for the propagating fire shortened MCR abandonment time.

Investigating the Effect of a North Wall on Energy Consumption of an East–West Oriented Single Span Greenhouse

Directory of Open Access Journals (Sweden)

H Ghasemi Mobtaker

2017-10-01

Full Text Available Introduction Greenhouse is a structure which provides the best condition for the maximum plants growth during the cold seasons. In cold climate zones such as Tabriz province, Iran, the greenhouse heating is one of the most energy consumers. It has been estimated that the greenhouse heating cost is attributed up to 30% of the total operational costs of the greenhouses. Renewable energy resources are clean alternatives that can be used in greenhouse heating. Among the renewable energy resources, solar energy has the highest potential around the world. In this regard, application of solar energy in greenhouse heating during the cold months of a year could be considerable. The rate of thermal energy required inside the greenhouse depends on the solar radiation received inside the greenhouse. Using a north brick wall in an east-west oriented greenhouse can increase the absorption of solar radiation and consequently reduces the thermal and radiation losses. Therefore, the main objective of the present study is to investigate the effect of implementing of a north wall on the solar radiation absorption and energy consumption of an east-west oriented single span greenhouse in Tabriz. Materials and Methods This study was carried out in Tabriz and a steady state analysis was used to predict the energy consumption of a single span greenhouse. For this purpose, thermal energy balance equations for different components of the greenhouse including the soil layer, internal air and plants were presented. For investigating the effect of the north wall on the energy consumption, the Ft and Fn parameters were used to calculate the radiation loss from the walls of the greenhouses. These factors were determined using a 3D–shadow analysis by Auto–CAD software. An east-west oriented single span greenhouse which has a north brick wall and is covered with a single glass sheet with 4 mm thickness was applied to validate the developed models. The measurements were

The influence of wall resonances on the levitation of objects in a single-axis acoustic processing chamber

Science.gov (United States)

Ross, B. B.

1980-01-01

Instabilities were observed in high temperature, single axis acoustic processing chambers. At certain temperatures, strong wall resonances were generated within the processing chamber itself and these transverse resonances were thought sufficient to disrupt the levitation well. These wall resonances are apparently not strong enough to cause instabilities in the levitation well.

Fire Resistant Materials

Science.gov (United States)

1982-01-01

Fire hazard is greater in atmospheres containing a high percentage of oxygen under pressure. NASA intensified its fire safety research after a 1967 Apollo fire. A chemically treated fabric called Durette developed by Monsanto Company, which will not burn or produce noxious fumes, was selected as a material for Apollo astronaut garments. Monsanto sold production rights for this material to Fire Safe Products (FSP). Durette is now used for a wide range of applications such as: sheets, attendants' uniforms in hyperbaric chambers; crew's clothing, furniture and interior walls of diving chambers operated by the U.S. Navy and other oceanographic companies and research organizations. Pyrotect Safety Equipment, Minneapolis, MN produces Durette suits for auto racers, refuelers and crew chiefs from material supplied by FSP. FSP also manufactures Durette bags for filtering gases and dust from boilers, electric generators and similar systems. Durette bags are an alternative to other felted fiber capable of operating at high temperature that cost twice as much.

Record Endurance for Single-Walled Carbon Nanotube–Based Memory Cell

Directory of Open Access Journals (Sweden)

Yang Y

2010-01-01

Full Text Available Abstract We study memory devices consisting of single-walled carbon nanotube transistors with charge storage at the SiO2/nanotube interface. We show that this type of memory device is robust, withstanding over 105 operating cycles, with a current drive capability up to 10−6 A at 20 mV drain bias, thus competing with state-of-the-art Si-devices. We find that the device performance depends on temperature and pressure, while both endurance and data retention are improved in vacuum.

Timber frame walls

DEFF Research Database (Denmark)

Hansen, Ernst Jan de Place; Brandt, Erik

2010-01-01

A ventilated cavity is usually considered good practice for removing moisture behind the cladding of timber framed walls. Timber frame walls with no cavity are a logical alternative as they are slimmer and less expensive to produce and besides the risk of a two-sided fire behind the cladding....... It was found that the specific damages made to the vapour barrier as part of the test did not have any provable effect on the moisture content. In general elements with an intact vapour barrier did not show a critical moisture content at the wind barrier after four years of exposure....

Single vs. dual color fire detection systems: operational tradeoffs

Science.gov (United States)

Danino, Meir; Danan, Yossef; Sinvani, Moshe

2017-10-01

In attempt to supply a reasonable fire plume detection, multinational cooperation with significant capital is invested in the development of two major Infra-Red (IR) based fire detection alternatives, single-color IR (SCIR) and dual-color IR (DCIR). False alarm rate was expected to be high not only as a result of real heat sources but mainly due to the IR natural clutter especially solar reflections clutter. SCIR uses state-of-the-art technology and sophisticated algorithms to filter out threats from clutter. On the other hand, DCIR are aiming at using additional spectral band measurements (acting as a guard), to allow the implementation of a simpler and more robust approach for performing the same task. In this paper we present the basics of SCIR & DCIR architecture and the main differences between them. In addition, we will present the results from a thorough study conducted for the purpose of learning about the added value of the additional data available from the second spectral band. Here we consider the two CO2 bands of 4-5 micron and of 2.5-3 micron band as well as off peak band (guard). The findings of this study refer also to Missile warning systems (MWS) efficacy, in terms of operational value. We also present a new approach for tunable filter to such sensor.

Light-harvesting dendrimer zinc-phthalocyanines chromophores labeled single-wall carbon nanotube nanoensembles: Synthesis and photoinduced electron transfer

Energy Technology Data Exchange (ETDEWEB)

Yang, Hongqin [Key Laboratory of Optoelectronic Science and Technology for Medicine, Ministry of Education and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou 350007 (China); Pan, Sujuan; Ma, Dongdong; He, Dandan; Wang, Yuhua [College of Chemistry & Engineering, Fujian Provincial Key Laboratory of Polymer Materials, Fujian Normal University, Fuzhou 350007 (China); Xie, Shusen [Key Laboratory of Optoelectronic Science and Technology for Medicine, Ministry of Education and Fujian Provincial Key Laboratory for Photonics Technology, Fujian Normal University, Fuzhou 350007 (China); Peng, Yiru, E-mail: yirupeng@fjnu.edu.cn [College of Chemistry & Engineering, Fujian Provincial Key Laboratory of Polymer Materials, Fujian Normal University, Fuzhou 350007 (China)

2016-11-15

A novel series of light-harvesting dendrimer zinc-phthalocyanines chromophores labeled-single-wall carbon nanotubes (SWNTs) nanoparticles, in which 0–2 generations dendrimer zinc phthalocyanines covalently linked with SWNTs using either ethylenediamine or hexamethylenediamine as the space linkers were prepared. The structures and morphologies of these nanoconjugates were comprehensively characterized by Raman spectroscopy, transmission electron microscopy and thermal gravimetric analysis methods. Their photophysical properties were investigated by fluorescence and time-resolved spectroscopic methods. The photoinduced intramolecular electron transfer occurred from phthalocyanines (donors) to SWNTs (acceptors). Besides, the electron transfer exchange rates and exchange efficacies between the dendritic phthalocyanines and single-wall carbon nanotubes increased as the length of spacer linker decreased, or as the dendritic generation increased. Cyclic voltammetry (CV) method further confirmed thermodynamics possibility of the electron transfer from phthalocyanines to single-wall carbon nanotubes. These new nanoconjugates are fundamentally important due to the synergy effects of both carbon nanotubes and dendrimer phthalocyanines, which may find potential applications in the fields of drug delivery, biological labeling, or others.

Remote Sensing Applied to the Study of Fire Regime Attributes and Their Influence on Post-Fire Greenness Recovery in Pine Ecosystems

Directory of Open Access Journals (Sweden)

Víctor Fernández-García

2018-05-01

Full Text Available We aimed to analyze the relationship between fire regime attributes and the post-fire greenness recovery of fire-prone pine ecosystems over the short (2-year and medium (5-year term after a large wildfire, using both a single and a combined fire regime attribute approach. We characterized the spatial (fire size, temporal (number of fires, fire recurrence, and return interval, and magnitude (burn severity of the last fire fire regime attributes throughout a 40-year period with a long-time series of Landsat imagery and ancillary data. The burn severity of the last fire was measured by the dNBR (difference of the Normalized Burn Ratio spectral index, and classified according to the ground reference values of the CBI (Composite Burn Index. Post-fire greenness recovery was obtained through the difference of the NDVI (Normalized Difference Vegetation Index between pre- and post-fire Landsat scenes. The relationship between fire regime attributes (single attributes: fire recurrence, fire return interval, and burn severity; combined attributes: fire recurrence-burn severity and fire return interval-burn severity and post-fire greenness recovery was evaluated using linear models. The results indicated that all the single and combined attributes significantly affected greenness recovery. The single attribute approach showed that high recurrence, short return interval and low severity situations had the highest vegetation greenness recovery. The combined attribute approach allowed us to identify a wider variety of post-fire greenness recovery situations than the single attribute one. Over the short term, high recurrence as well as short return interval scenarios showed the best post-fire greenness recovery independently of burn severity, while over the medium term, high recurrence combined with low severity was the most recovered scenario. This novel combined attribute approach (temporal plus magnitude could be of great value to forest managers in the

Laser-induced forward transfer of single-walled carbon nanotubes

Science.gov (United States)

Palla-Papavlu, A.; Dinescu, M.; Wokaun, A.; Lippert, T.

2014-10-01

The objective of this work is the application of laser-induced forward transfer (LIFT) for the fabrication of chemiresistor sensors. The receiver substrate is an array with metal electrodes and the active materials placed by LIFT are single-walled carbon nanotubes (SWCNT). The functionality of such sensors depends on the geometry of the active material onto the metallic electrodes. First the best geometry for the sensing materials and electrodes was determined, including the optimization of the process parameters for printing uniform pixels of SWCNT onto the sensor electrodes. The sensors were characterized in terms of their sensing characteristics, i.e., upon exposure to ammonia, proving the feasibility of LIFT.

Conjugated Polymer-Assisted Dispersion of Single-Wall Carbon Nanotubes : The Power of Polymer Wrapping

NARCIS (Netherlands)

Samanta, Suman Kalyan; Fritsch, Martin; Scherf, Ullrich; Gomulya, Widianta; Bisri, Satria Zulkarnaen; Loi, Maria Antonietta

CONSPECTUS: The future application of single-walled carbon nanotubes (SWNTs) in electronic (nano)devices is closely coupled to the availability of pure, semiconducting SWNTs and preferably, their defined positioning on suited substrates. Commercial carbon nanotube raw mixtures contain metallic as

Inkjet printing of aligned single-walled carbon-nanotube thin films

Science.gov (United States)

Takagi, Yuki; Nobusa, Yuki; Gocho, Shota; Kudou, Hikaru; Yanagi, Kazuhiro; Kataura, Hiromichi; Takenobu, Taishi

2013-04-01

We report a method for the inkjet printing of aligned single-walled carbon-nanotube (SWCNT) films by combining inkjet technology with the strong wettability contrast between hydrophobic and hydrophilic areas based on the patterning of self-assembled monolayers. Both the drying process control using the strong wettability boundary and the coffee-stain effect strongly promote the aggregation of SWCNTs along the contact line of a SWCNT ink droplet, thereby demonstrating our achievement of inkjet-printed aligned SWCNT films. This method could open routes for developing high-performance and environmentally friendly SWCNT printed electronics.

Fire propagation equation for the explicit identification of fire scenarios in a fire PSA

International Nuclear Information System (INIS)

Lim, Ho Gon; Han, Sang Hoon; Moon, Joo Hyun

2011-01-01

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a 2x3 rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification

Measurements in large JP-4 pool fires

International Nuclear Information System (INIS)

Keltner, N.R.; Kent, L.A.; Schneider, M.E.

1987-01-01

Over the past four years, Sandia National Laboratories has conducted a number of large pool fire tests to evaluate the design of radioactive material (RAM) shipping containers. Some of these tests have been designed to define the thermal environment and some have been used for certification testing. In each test there have been a number of fire diagnostic measurements. The simplest sets of diagnostics have involved measurements of temperature at several elevations on arrays of towers, measurements of hot wall heat flux with small calorimeters suspended from the towers, the average fuel recession rate, and the wind speed and direction. The most complex sets of diagnostics have included the above and in various tests added radiometers in the lower flame zone, centerline velocity measurements at a number of elevations, radiometers and calorimeters at the fuel surface, large cylindrical and flat plate calorimeters, infrared imaging, time resolved fuel recession rates, and a variety of soot particle concentration and size measurements made in the plume with a tethered balloon and an instrumented airplane. All of the large fires have been conducted in a 9.1 m by 18.3 m pool using JP-4 as the fuel. Typical duration is one-half hour. Covering all of the results is beyond the scope of a single paper. Conditionally sampled temperature and velocity measurements from one fire will be presented; for this fire, a 20 cm layer of fuel was floated on 61 cm of water. Pool surface heat flux, fuel recession rate data, and smoke emission data from a second fire are given. Because the wind has a strong effect on the temperature and velocity measurements, conditional sampling has been used to try to obtain data during periods of low winds. 10 refs., 3 figs

High-speed schlieren videography of vortex-ring impact on a wall

Science.gov (United States)

Kissner, Benjamin; Hargather, Michael; Settles, Gary

2011-11-01

Ring vortices of approximately 20 cm diameter are generated through the use of an Airzooka toy. To make the vortex visible, it is seeded with difluoroethane gas, producing a refractive-index difference with the air. A 1-meter-diameter, single-mirror, double-pass schlieren system is used to visualize the ring-vortex motion, and also to provide the wall with which the vortex collides. High-speed imaging is provided by a Photron SA-1 digital video camera. The Airzooka is fired toward the mirror almost along the optical axis of the schlieren system, so that the view of the vortex-mirror collision is normal to the path of vortex motion. Vortex-wall interactions similar to those first observed by Walker et al. (JFM 181, 1987) are recorded at high speed. The presentation will consist of a screening and discussion of these video results.

Optical spectroscopy of iodine-doped single-wall carbon nanotubes of different diameter

International Nuclear Information System (INIS)

Tonkikh, Alexander A.; Obraztsova, Elena D.; Pozharov, Anatolii S.; Obraztsova, Ekaterina A.; Belkin, Alexey V.

2012-01-01

Single-wall carbon nanotubes with polyiodide chains inside are interesting from two points of view. According to predictions, first, the iodine structure type inside the nanotube is determined by the nanotube geometry. Second, after iodination all nanotubes become metallic. In this work, we made an attempt to check both predictions. To study the diameter-dependent properties we have taken for a gas-phase iodination the pristine single-wall carbon nanotubes grown by three different techniques providing a different average diameter: a chemical vapor deposition with a Co/Mo catalyst (CoMoCat) with a diameter range (0.6-1.3) nm, a high-pressure CO decomposition (HiPCO) - a diameter range (0.8-1.5) nm, and an aerosol technique with Fe catalyst - a diameter range (1.3-2.0) nm. The Raman spectra have shown a complication of the polyiodide chain structure while the nanotube diameter increased. The optical spectroscopy data (a suppression of E 11 band in the UV-Vis-NIR absorption spectrum) have confirmed the theoretical prediction about transformation of all nanotubes into metallic phase after doping. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

High-resolution 13C nuclear magnetic resonance evidence of phase transition of Rb,Cs-intercalated single-walled nanotubes

KAUST Repository

Bouhrara, M.

2011-09-06

We present 13 C high-resolution magic-angle-turning (MAT) and magic angle spinning nuclear magnetic resonance data of Cs and Rb intercalated single walled carbon nanotubes. We find two distinct phases at different intercalation levels. A simple charge transfer is applicable at low intercalation level. The new phase at high intercalation level is accompanied by a hybridization of alkali (s) orbitals with the carbon (sp2) orbitals of the single walled nanotubes, which indicate bundle surface sites is the most probable alkali site.

Comparative Study of Single- and Multi-Wall Carbon Nanotubes with Application in Cerebral Aneurysm

Directory of Open Access Journals (Sweden)

Rodica-Mariana Ion

2011-01-01

Full Text Available Helping improve humanity is one of the promises of nanotech-
nology and nanomedicine. This paper will highlight some of the research findings in the nanomedicine area by testing some single- and multi-walls carbon nanotubues in rats cerebral aneurisms.

Pressure effects on single wall carbon nanotube bundles

International Nuclear Information System (INIS)

Teredesai, P.V.; Sharma, S.M.; Karmakar, S.; Sikka, S.K.; Govindaraj, A.; Rao, C.N.R.

2001-01-01

We report high pressure Raman studies on single wall carbon nanotube bundles under hydrostatic conditions using two different pressure transmitting media, alcohol mixture and pure water. The radial and tangential modes show a blue shift when SWNT bundle is immersed in the liquids at ambient pressures. The pressure dependence of the radial modes is the same in both liquids. However, the pressure derivatives dω/dP of the tangential modes are slightly higher for the water medium. Raman results are compared with studies under non-hydrostatic conditions and with recent high-pressure X-ray studies. It is seen that the mode frequencies of the recovered sample after pressure cycling from 26 GPa are downshifted by ∝7-10 cm -1 as compared to the starting sample. (orig.)

A 66 fs highly stable single wall carbon nanotube mode locked fiber laser

International Nuclear Information System (INIS)

Yu, Zhenhua; Zhang, Xiao; Dong, Xinzheng; Tian, Jinrong; Song, Yanrong; Wang, Yonggang

2014-01-01

We demonstrate a highly stable mode locked fiber laser based on single wall carbon nanotubes. The mode locking is achieved by the evanescent field interaction of the propagating light with a single wall carbon nanotube saturable absorber in a microfiber. The pulse width is 66 fs, which, to the best of our knowledge, is the shortest pulse achieved in a carbon nanotube mode locked fiber laser. The maximum average output power is 26 mW, which is about 20 times larger than that of a typical carbon nanotube mode locked fiber laser. The center of the wavelength is 1555 nm, with 54 nm spectral width. The repetition rate is 146 MHz. To investigate the laser’s stability, the output pulses are monitored for 120 h and there is no significant degradation of the laser spectral width or shape. (paper)

Transport properties of a potassium-doped single-wall carbon nanotube rope

International Nuclear Information System (INIS)

Lee, R. S.; Kim, H. J.; Fischer, J. E.; Lefebvre, J.; Radosavljevic, M.; Hone, J.; Johnson, A. T.

2000-01-01

Four-probe resistance vs temperature and gate voltage are reported for an individual single-wall carbon nanotube rope before and after doping in situ with potassium. All the features in R(T) from unoriented bulk material, before and after doping, are qualitatively reproduced by the rope data. The 5.3 K conductance of the pristine rope decreases with positive gate voltage, while G vs V g becomes featureless after K doping. (c) 2000 The American Physical Society

Buckling of ZnS-filled single-walled carbon nanotubes – The influence of aspect ratio

KAUST Repository

Monteiro, André O.; Da Costa, Pedro M. F. J.; Cachim, Paulo B.; Holec, David

2014-01-01

The mechanical response of single-walled carbon nanotubes (SWCNT) filled with crystalline zinc sulphide (ZnS) nanowires under uniaxial compression is studied using classical molecular dynamics. These simulations were used to analyse the behaviour

Failure analysis of the boiler water-wall tube

OpenAIRE

S.W. Liu; W.Z. Wang; C.J. Liu

2017-01-01

Failure analysis of the boiler water-wall tube is presented in this work. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy were carried out. Tube wall thickness measurements were performed on the ruptured tube. The fire-facing side of the tube was observed to have experienced significant wall thinning. The composition of the matrix material of the tu...

Lifshitz-type formulas for graphene and single-wall carbon nanotubes: van der Waals and Casimir interactions

International Nuclear Information System (INIS)

Bordag, M.; Geyer, B.; Klimchitskaya, G. L.; Mostepanenko, V. M.

2006-01-01

Lifshitz-type formulas are obtained for the van der Waals and Casimir interaction between graphene and a material plate, graphene and an atom or a molecule, and between a single-wall carbon nanotube and a plate. The reflection properties of electromagnetic oscillations on graphene are governed by the specific boundary conditions imposed on the infinitely thin positively charged plasma sheet, carrying a continuous fluid with some mass and charge density. The obtained formulas are applied to graphene interacting with Au and Si plates, to hydrogen atoms and molecules interacting with graphene, and to single-wall carbon nanotubes interacting with Au and Si plates. The generalizations to more complicated carbon nanostructures are discussed

Designing fire safe interiors.

Science.gov (United States)

Belles, D W

1992-01-01

Any product that causes a fire to grow large is deficient in fire safety performance. A large fire in any building represents a serious hazard. Multiple-death fires almost always are linked to fires that grow quickly to a large size. Interior finishes have large, continuous surfaces over which fire can spread. They are regulated to slow initial fire growth, and must be qualified for use on the basis of fire tests. To obtain meaningful results, specimens must be representative of actual installation. Variables--such as the substrate, the adhesive, and product thickness and density--can affect product performance. The tunnel test may not adequately evaluate some products, such as foam plastics or textile wall coverings, thermoplastic materials, or materials of minimal mass. Where questions exist, products should be evaluated on a full-scale basis. Curtains and draperies are examples of products that ignite easily and spread flames readily. The present method for testing curtains and draperies evaluates one fabric at a time. Although a fabric tested alone may perform well, fabrics that meet test standards individually sometimes perform poorly when tested in combination. Contents and furnishings constitute the major fuels in many fires. Contents may involve paper products and other lightweight materials that are easily ignited and capable of fast fire growth. Similarly, a small source may ignite many items of furniture that are capable of sustained fire growth. Upholstered furniture can reach peak burning rates in less than 5 minutes. Furnishings have been associated with many multiple-death fires.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermo-sensitive liposomes loaded with doxorubicin and lysine modified single-walled carbon nanotubes as tumor-targeting drug delivery system.

Science.gov (United States)

Zhu, Xiali; Xie, Yingxia; Zhang, Yingjie; Huang, Heqing; Huang, Shengnan; Hou, Lin; Zhang, Huijuan; Li, Zhi; Shi, Jinjin; Zhang, Zhenzhong

2014-11-01

This report focuses on the thermo-sensitive liposomes loaded with doxorubicin and lysine-modified single-walled carbon nanotube drug delivery system, which was designed to enhance the anti-tumor effect and reduce the side effects of doxorubicin. Doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes was prepared by reverse-phase evaporation method, the mean particle size was 232.0 ± 5.6 nm, and drug entrapment efficiency was 86.5 ± 3.7%. The drug release test showed that doxorubicin released more quickly at 42℃ than at 37℃. Compared with free doxorubicin, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes could efficiently cross the cell membranes and afford higher anti-tumor efficacy on the human hepatic carcinoma cell line (SMMC-7721) cells in vitro. For in vivo experiments, the relative tumor volumes of the sarcomaia 180-bearing mice in thermo-sensitive liposomes group and doxorubicin group were significantly smaller than those of N.S. group. Meanwhile, the combination of near-infrared laser irradiation at 808 nm significantly enhanced the tumor growth inhibition both on SMMC-7721 cells and the sarcomaia 180-bearing mice. The quality of life such as body weight, mental state, food and water intake of sarcomaia 180 tumor-bearing mice treated with doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes were much higher than those treated with doxorubicin. In conclusion, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes combined with near-infrared laser irradiation at 808 nm may potentially provide viable clinical strategies for targeting delivery of anti-cancer drugs. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

Science.gov (United States)

Günay, E.

2016-04-01

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

International Nuclear Information System (INIS)

Günay, E.

2016-01-01

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

Energy Technology Data Exchange (ETDEWEB)

Günay, E. [Gazi University, Mechanical Engineering Department, 06570, Ankara (Turkey)

2016-04-21

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values. In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.

On the charge transfer between single-walled carbon nanotubes and graphene

International Nuclear Information System (INIS)

Rao, Rahul; Pierce, Neal; Dasgupta, Archi

2014-01-01

It is important to understand the electronic interaction between single-walled carbon nanotubes (SWNTs) and graphene in order to use them efficiently in multifunctional hybrid devices. Here, we deposited SWNT bundles on graphene-covered copper and SiO 2 substrates by chemical vapor deposition and investigated the charge transfer between them by Raman spectroscopy. Our results revealed that, on both copper and SiO 2 substrates, graphene donates electrons to the SWNTs, resulting in p-type doped graphene and n-type doped SWNTs.

Plasmon excitation in single wall carbon nanotubes by penetrating charged particles

International Nuclear Information System (INIS)

Segui, Silvina; Gervasoni, Juana L; Arista, Néstor R; Mowbray, Duncan J; Mišković, Zoran L

2012-01-01

In this work we study the excitation of plasmons due to the incidence of a charged particle passing through a single wall carbon nanotube. We use a quantized hydrodynamic, in which the σ and π electrons characteristic of these carbonaceous structures are depicted as two interacting 2-dimensional fluids, to calculate the average number of plasmons excited. We analyze the contribution of the different plasmon modes in a variety of configurations, and study the energy lost by the incident particle.

Large scale fire experiments in the HDR containment as a basis for fire code development

International Nuclear Information System (INIS)

Hosser, D.; Dobbernack, R.

1993-01-01

Between 1984 and 1991 7 different series of large scale fire experiments and related numerical and theoretical investigations have been performed in the containment of a high pressure reactor in Germany (known as HDR plant). The experimental part included: gas burner tests for checking the containment behaviour; naturally ventilated fires with wood cribs; naturally and forced ventilated oil pool fires; naturally and forced ventilated cable fires. Many results of the oil pool and cable fires can directly be applied to predict the impact of real fires at different locations in a containment on mechanical or structural components as well as on plant personnel. But the main advantage of the measurements and observations was to serve as a basis for fire code development and validation. Different types of fire codes have been used to predict in advance or evaluate afterwards the test results: zone models for single room and multiple room configurations; system codes for multiple room configurations; field models for complex single room configurations. Finally, there exist codes of varying degree of specialization which have proven their power and sufficient exactness to predict fire effects as a basis for optimum fire protection design. (author)

Diameter grouping in bulk samples of single-walled carbon nanotubes from optical absorption spectroscopy

NARCIS (Netherlands)

Golden, M.S.; Fink, J.; Dunsch, L.; Bauer, H.-D.; Reibold, M.; Knupfer, M.; Friedlein, R.; Pichler, T.; Jost, O.

1999-01-01

The influence of the synthesis parameters on the mean characteristics of single-wall carbon nanotubes in soot produced by the laser vaporization of graphite has been analyzed using optical absorption spectroscopy. The abundance and mean diameter of the nanotubes were found to be most influenced by

TiS2 and ZrS2 single- and double-wall nanotubes: first-principles study.

Science.gov (United States)

Bandura, Andrei V; Evarestov, Robert A

2014-02-15

Hybrid density functional theory has been applied for investigations of the electronic and atomic structure of bulk phases, nanolayers, and nanotubes based on titanium and zirconium disulfides. Calculations have been performed on the basis of the localized atomic functions by means of the CRYSTAL-2009 computer code. The full optimization of all atomic positions in the regarded systems has been made to study the atomic relaxation and to determine the most favorable structures. The different layered and isotropic bulk phases have been considered as the possible precursors of the nanotubes. Calculations on single-walled TiS2 and ZrS2 nanotubes confirmed that the nanotubes obtained by rolling up the hexagonal crystalline layers with octahedral 1T morphology are the most stable. The strain energy of TiS2 and ZrS2 nanotubes is small, does not depend on the tube chirality, and approximately obeys to D(-2) law (D is nanotube diameter) of the classical elasticity theory. It is greater than the strain energy of the similar TiO2 and ZrO2 nanotubes; however, the formation energy of the disulfide nanotubes is considerably less than the formation energy of the dioxide nanotubes. The distance and interaction energy between the single-wall components of the double-wall nanotubes is proved to be close to the distance and interaction energy between layers in the layered crystals. Analysis of the relaxed nanotube shape using radial coordinate of the metal atoms demonstrates a small but noticeable deviation from completely cylindrical cross-section of the external walls in the armchair-like double-wall nanotubes. Copyright © 2013 Wiley Periodicals, Inc.

Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm.

Science.gov (United States)

Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M; Mutter, George L; Ozkan, Mihrimah; Ozkan, Cengiz S; Demirci, Utkan

2016-08-19

Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1-25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm

Science.gov (United States)

Asghar, Waseem; Shafiee, Hadi; Velasco, Vanessa; Sah, Vasu R.; Guo, Shirui; El Assal, Rami; Inci, Fatih; Rajagopalan, Adhithi; Jahangir, Muntasir; Anchan, Raymond M.; Mutter, George L.; Ozkan, Mihrimah; Ozkan, Cengiz S.; Demirci, Utkan

2016-08-01

Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1-25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

Visualizing the growth dynamics of individual single-wall carbon nanotubes

DEFF Research Database (Denmark)

Wagner, Jakob Birkedal; Zhang, Lili; He, Maoshuai

In order to meet the increasing demand of faster and more flexible electronics and optical devices and at the same time decrease the use of the critical metals, carbon based devices are in fast development. Single walled carbon nanotube (SWCNT) based electronics is a way of addressing...... around the studied sample at elevated temperature gives a unique way of monitoring gas-solid interactions such as CNT growth. Here we show the direct experimental evidence on the growth dynamics of SW-CNTs from Co/MgO catalysts using CO as carbon source inside the environmental TEM. The evolution...

Exposure of a liquefied gas container to an external fire

International Nuclear Information System (INIS)

Raj, Phani K.

2005-01-01

In liquefied gas, bulk-storage facilities and plants, the separation distances between storage tanks and between a tank and a line of adjoining property that can be built are governed by local regulations and/or codes (e.g. National Fire Protection Association (NFPA) 58, 2004). Separation distance requirements have been in the NFPA 58 Code for over 60 years; however, no scientific foundations (either theoretical or experimental) are available for the specified distances. Even though the liquefied petroleum gas (LPG) industry has operated safely over the years, there is a question as to whether the code-specified distances provide sufficient safety to LPG-storage tanks, when they are exposed to large external fires. A radiation heat-transfer-based model is presented in this paper. The temporal variation of the vapor-wetted tank-wall temperature is calculated when exposed to thermal radiation from an external, non-impinging, large, 30.5 m (100 ft) diameter, highly radiative, hydrocarbon fuel (pool) fire located at a specified distance. Structural steel wall of a pressurized, liquefied gas container (such as the ASME LP-Gas tank) begins to lose its strength, when the wall temperature approaches a critical temperature, 810 K (1000 deg F). LP-Gas tank walls reaching close to this temperature will be a cause for major concern because of increased potential for tank failure, which could result in catastrophic consequences. Results from the model for exposure of different size ASME (LP-Gas) containers to a hydrocarbon pool fire of 30.5 m (100 ft) in diameter, located with its base edge at the separation distances specified by NFPA 58 [NFPA 58, Liquefied Petroleum Gas Code, Table 6.3.1, 2004 ed., National Fire Protection Association, Quincy, MA, 2004] indicate that the vapor-wetted wall temperature of the containers never reach the critical temperature under common wind conditions (0, 5 and 10 m/s), with the flame tilting towards the tank. This indicates that the separation

Novel Catalyst for the Chirality Selective Synthesis of Single Walled Carbon Nanotubes

Science.gov (United States)

2015-05-12

Final 3. DATES COVERED (From - To) 03-April-2013 to 02-April-2015 4. TITLE AND SUBTITLE Novel Catalyst for the Chirality Selective...Distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Chiral single walled carbon nanotubes (SWCNTs) are known to possess unique... chirality control in SWCNT synthesis. A model catalyst based on CoSO4/SiO2 was developed that showed good selectivity to (9,8) nanotubes. Remote plasma

Demonstration of advanced combustion NO(sub X) control techniques for a wall-fired boiler. Project performance summary, Clean Coal Technology Demonstration Program

International Nuclear Information System (INIS)

None

2001-01-01

The project represents a landmark assessment of the potential of low-NO(sub x) burners, advanced overtire air, and neural-network control systems to reduce NO(sub x) emissions within the bounds of acceptable dry-bottom, wall-fired boiler performance. Such boilers were targeted under the Clean Air Act Amendments of 1990 (CAAA). Testing provided valuable input to the Environmental Protection Agency ruling issued in March 1994, which set NO(sub x) emission limits for ''Group 1'' wall-fired boilers at 0.5 lb/10(sup 6) Btu to be met by January 1996. The resultant comprehensive database served to assist utilities in effectively implementing CAAA compliance. The project is part of the U.S. Department of Energy's Clean Coal Technology Demonstration Program established to address energy and environmental concerns related to coal use. Five nationally competed solicitations sought cost-shared partnerships with industry to accelerate commercialization of the most advanced coal-based power generation and pollution control technologies. The Program, valued at over$5 billion, has leveraged federal funding twofold through the resultant partnerships encompassing utilities, technology developers, state governments, and research organizations. This project was one of 16 selected in May 1988 from 55 proposals submitted in response to the Program's second solicitation. Southern Company Services, Inc. (SCS) conducted a comprehensive evaluation of the effects of Foster Wheeler Energy Corporation's (FWEC) advanced overfire air (AOFA), low-NO(sub x) burners (LNB), and LNB/AOFA on wall-fired boiler NO(sub x) emissions and other combustion parameters. SCS also evaluated the effectiveness of an advanced on-line optimization system, the Generic NO(sub x) Control Intelligent System (GNOCIS). Over a six-year period, SCS carried out testing at Georgia Power Company's 500-MWe Plant Hammond Unit 4 in Coosa, Georgia. Tests proceeded in a logical sequence using rigorous statistical analyses to

Exploration of burning plasmas in FIRE

International Nuclear Information System (INIS)

Meade, D.M.; Kessel, C.E.; Hammett, G.W.

2003-01-01

The Advanced Reactor Innovation Evaluation Studies (ARIES) have identified the key physics and technical issues that must be resolved before attractive fusion reactors can be designed and built. The Fusion Ignition Research Experiment (FIRE) design study has been undertaken to define the lowest cost facility to address the key burning plasma and advanced tokamak physics issues identified in the ARIES studies. The configuration chosen for FIRE is similar to that of ARIES-AT, a steady-state advanced tokamak reactor based on a high-βand high-bootstrap-current operating regime. The key advanced tokamak features of FIRE are: strong plasma shaping, double-null pumping divertors, low toroidal field ripple ( cr ). A longer term goal of FIRE is to explore 'steady-state' high-β advanced tokamak regimes with high bootstrap fractions (f BS ) ∼ 75% at β N ∼ 4 and moderate fusion gain (Q ∼ 5 to 10) under quasi-steady-state conditions for ∼ 3 τ cr . FIRE activities have focused on the physics and engineering assessment of a compact, high-field, cryogenic-copper-coil tokamak with: R o = 2.14 m, a = 0.595 m, B t (R o ) = 6 to 10T, I p = 4.5 to 7.7 MA with a flat top time of 40 to 20 s for 150 MW of fusion power. FIRE will utilize only metal plasma facing components; Be coated tiles for the first wall and W brush divertors to reduce tritium retention as required for fusion reactors. FIRE will be able to test divertor and plasma facing components under reactor relevant power densities since the fusion power density of 6 MWm -3 and neutron wall loading of 2.3 MWm -2 approach those expected in a reactor. (author)

Study of the Emission Characteristics of Single-Walled CNT and Carbon Nano-Fiber Pyrograf III

Science.gov (United States)

Mousa, Marwan S.; Al-Akhras, M.-Ali H.; Daradkeh, Samer

2018-02-01

Field emission microscopy measurements from Single-Walled Carbon Nanotubes (SWCNTs) and Carbon Nano-Fibers Pyrograf III PR-1 (CNF) were performed. Details of the materials employed in the experiments are as follows: (a) Carbon Nano-Fibers Pyrograf III PR-1 (CNF), having an average fiber diameter that is ranging between (100-200) nm with a length of (30-100) μm. (b) Single walled Carbon Nanotubes were produced by high-pressure CO over Fe particle (HiPCO: High-Pressure Carbon Monoxide process), having an average diameter ranging between (1-4) nm with a length of (1-3) μm. The experiments were performed under vacuum pressure value of (10-7 mbar). The research work reported here includes the field electron emission current-voltage (I-V) characteristics and presented as Fowler-Nordheim (FN) plots and the spatial emission current distributions (electron emission images) obtained and analyzed in terms of electron source features. For both the SWCNT and the CNF a single spot pattern for the electron spatial; distributions were observed.

Electroluminescence from single-wall carbon nanotube network transistors.

Science.gov (United States)

Adam, E; Aguirre, C M; Marty, L; St-Antoine, B C; Meunier, F; Desjardins, P; Ménard, D; Martel, R

2008-08-01

The electroluminescence (EL) properties from single-wall carbon nanotube network field-effect transistors (NNFETs) and small bundle carbon nanotube field effect transistors (CNFETs) are studied using spectroscopy and imaging in the near-infrared (NIR). At room temperature, NNFETs produce broad (approximately 180 meV) and structured NIR spectra, while they are narrower (approximately 80 meV) for CNFETs. EL emission from NNFETs is located in the vicinity of the minority carrier injecting contact (drain) and the spectrum of the emission is red shifted with respect to the corresponding absorption spectrum. A phenomenological model based on a Fermi-Dirac distribution of carriers in the nanotube network reproduces the spectral features observed. This work supports bipolar (electron-hole) current recombination as the main mechanism of emission and highlights the drastic influence of carrier distribution on the optoelectronic properties of carbon nanotube films.

Fire-through Ag contact formation for crystalline Si solar cells using single-step inkjet printing.

Science.gov (United States)

Kim, Hyun-Gang; Cho, Sung-Bin; Chung, Bo-Mook; Huh, Joo-Youl; Yoon, Sam S

2012-04-01

Inkjet-printed Ag metallization is a promising method of forming front-side contacts on Si solar cells due to its non-contact printing nature and fine grid resolution. However, conventional Ag inks are unable to punch through the SiN(x) anti-reflection coating (ARC) layer on emitter Si surfaces. In this study, a novel formulation of Ag ink is examined for the formation of fire-through contacts on a SiN(x)-coated Si substrate using the single-step printing of Ag ink, followed by rapid thermal annealing at 800 degrees C. In order to formulate Ag inks with fire-through contact formation capabilities, a liquid etching agent was first formulated by dissolving metal nitrates in an organic solvent and then mixing the resulting solution with a commercial Ag nanoparticle ink at various volume ratios. During the firing process, the dissolved metal nitrates decomposed into metal oxides and acted in a similar manner to the glass frit contained in Ag pastes for screen-printed Ag metallization. The newly formulated ink with a 1 wt% loading ratio of metal oxides to Ag formed finely distributed Ag crystallites on the Si substrate after firing at 800 degrees C for 1 min.

Advances in NO2 sensing with individual single-walled carbon nanotube transistors.

Science.gov (United States)

Chikkadi, Kiran; Muoth, Matthias; Roman, Cosmin; Haluska, Miroslav; Hierold, Christofer

2014-01-01

The charge carrier transport in carbon nanotubes is highly sensitive to certain molecules attached to their surface. This property has generated interest for their application in sensing gases, chemicals and biomolecules. With over a decade of research, a clearer picture of the interactions between the carbon nanotube and its surroundings has been achieved. In this review, we intend to summarize the current knowledge on this topic, focusing not only on the effect of adsorbates but also the effect of dielectric charge traps on the electrical transport in single-walled carbon nanotube transistors that are to be used in sensing applications. Recently, contact-passivated, open-channel individual single-walled carbon nanotube field-effect transistors have been shown to be operational at room temperature with ultra-low power consumption. Sensor recovery within minutes through UV illumination or self-heating has been shown. Improvements in fabrication processes aimed at reducing the impact of charge traps have reduced the hysteresis, drift and low-frequency noise in carbon nanotube transistors. While open challenges such as large-scale fabrication, selectivity tuning and noise reduction still remain, these results demonstrate considerable progress in transforming the promise of carbon nanotube properties into functional ultra-low power, highly sensitive gas sensors.

Effects of single-walled carbon nanotubes on the bioavailability of PCBs in field-contaminated sediments

Science.gov (United States)

Adsorption of hydrophobic organic contaminants (HOCs) to black carbon is a well studied phenomenon. One emerging class of engineered black carbon materials are single-walled carbon nanotubes (SWNT). Little research has investigated the potential of SWNT to adsorb and sequester HO...

Pre test parametric studies on single compartment vented enclosure

International Nuclear Information System (INIS)

Sharma, Pavan K.; Gera, B.; Singh, R.K.; Vaze, K.K.

2011-01-01

Establishing a proper design fire scenario is a challenging task and essential component for conducting fire safety design of buildings. A design fire scenario is a qualitative description of a fire with time identifying key events that characterize the fire (ignition, growth, flashover, fully-developed, and decay stages of fire). Proper fire safety design requires the appropriate selection of design fires against which the performance of the building is evaluated. The selection of the design fires directly impacts all aspects of fire safety performance, including the structural fire resistance, compartmentation against fire spread, egress systems, manual or automatic detection systems, suppression systems, and smoke control. The parameters affecting design fires include, the type, amount and arrangement of combustible materials, the ventilation conditions (air supply conditions, door/window open), and size of the compartment of fire origin. A design fire is a quantitative description of the characteristics of a fire, such as heat release rate (HRR), size of fire and its rate of spread, yield of products of combustion, and hot gas temperatures. Design fires are based on fire scenarios that replicate real fires. Six Computational Fluid Dynamics (CFD) numerical simulations were conducted in order to investigate the effect of fire load on fire dynamics in a) iso corner fire configuration b) IIT Delhi single compartment of a size of 5.0 m long, 5.0 m wide and 5.0 m high with doorway opening of 1m x 3m with centre fire of size 0.5 m x 0.5m. These types of simulation are carried out for deciding about the instrumentation scheme, safety aspect, and optimization of proposed experiments for National Fire Test Facility as pretest calculations. The simulations results are summarized in various identified applied parameter which are useful in terms of understanding the complex fire dynamics, validating the numerical tolls against experiments and using them (in form of values

Non-covalent conjugates of single-walled carbon nanotubes and folic acid for interaction with cells overexpressing folate receptors

DEFF Research Database (Denmark)

Castillo, John J.; Rindzevicius, Tomas; Novoa, Leidy V.

2013-01-01

We here present amethod to form a noncovalent conjugate of single-walled carbon nanotubes and folic acid aimed to interact with cells over-expressing folate receptors. The bonding was obtained without covalent chemical functionalization using a simple, rapid “one pot” synthesis method. The zeta...... a low toxicity of the conjugates in the THP-1 cells. The low toxicity and the cellular uptake of single-walled carbon nanotube–folic acid by cancer cells suggest their potential use in carbon nanotube-based drug delivery systems and in the diagnosis of cancer or tropical diseases such as leishmaniasis....

The Kinetics of Chirality Assignment in Catalytic Single Walled Carbon Nanotube Growth

OpenAIRE

Xu, Ziwei; Yan, Tianying; Ding, Feng

2014-01-01

Chirality-selected single-walled carbon nanotubes (SWCNTs) ensure a great potential of building ~1 nm sized electronics. However, the reliable method for chirality-selected SWCNT is still pending. Here we present a theoretical study on the SWCNT's chirality assignment and control during the catalytic growth. This study reveals that the chirality of a SWCNT is determined by the kinetic incorporation of the pentagon formation during SWCNT nucleation. Therefore, chirality is randomly assigned on...

Risk evaluation of embedded, single-walled liquid low-level waste piping at Oak Ridge National Laboratory. ESD Publication 4315

International Nuclear Information System (INIS)

1994-10-01

Four categories of liquid low-level radioactive waste (LLLW) systems are defined in the Federal Facility Agreement (FFA) for the Oak Ridge Reservation (ORR). Categories A and B are new and fully compliant existing systems, respectively: Category C is singly contained and must be removed from service, and Category D is inactive. The FFA requires that secondary containment and leak detection be provided for all Category A and B piping in the LLLW System at Oak Ridge National Laboratory (ORNL); however, as noted in the D2 revision of the secondary containment design demonstration report (DOE 1994), some sections of single-walled embedded piping in Category B underground vaults at three ORNL facilities do not meet this requirement. A risk evaluation was performed in order compare the potential radiation dose to a member of the public that could result from a postulated leak in the single-walled pipes with projected radiation exposure to the workers who would modify the piping to meet FFA requirements. The risk to human health from replacing segments of embedded, single-walled piping in the LLW system is higher than the risk of leaving the piping as it is

Effects of residual aberrations explored on single-walled carbon nanotubes

International Nuclear Information System (INIS)

Biskupek, Johannes; Hartel, Peter; Haider, Maximilian; Kaiser, Ute

2012-01-01

The effects of geometric residual aberrations such as coma B 2 and two-fold astigmatism A 1 on the contrast in aberration corrected high resolution transmission electron microscopy (HRTEM) images are investigated on single-walled carbon nanotubes (SWNT). The individual aberrations are adjusted and set up manually using an imaging C S -corrector. We demonstrate how coma B 2 can be recognized by an experienced user directly in the image and how it blurs the contrast. Even with uncorrected (resolution limiting) spherical aberration C S the coma B 2 has to be considered and must be minimized. Limits for a tolerable coma are given. The experiments are confirmed by image simulations. -- Highlights: ► Individual effects of residual aberrations such as B 2 , A 1 , and C S are demonstrated. ► Experimental HRTEM and simulated images of carbon nanotubes are compared. ► A detection limit of 50 nm B 2 in a single HRTEM image is determined.

Thermal Pretreatment of Wood for Co-gasification/co-firing of Biomass and Coal

Energy Technology Data Exchange (ETDEWEB)

Wang, Ping [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Howard, Bret [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Hedges, Sheila [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Morreale, Bryan [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Van Essendelft, Dirk [National Energy Technology Lab. (NETL), Morgantown, WV (United States); Berry, David [National Energy Technology Lab. (NETL), Morgantown, WV (United States)

2013-10-29

Utilization of biomass as a co-feed in coal and biomass co-firing and co-gasification requires size reduction of the biomass. Reducing biomass to below 0.2 mm without pretreatment is difficult and costly because biomass is fibrous and compressible. Torrefaction is a promising thermal pretreatment process and has the advantages of increasing energy density, improving grindability, producing fuels with more homogenous compositions and hydrophobic behavior. Temperature is the most important factor for the torrefaction process. Biomass grindability is related to cell wall structure, thickness and composition. Thermal treatment such as torrefaction can cause chemical changes that significantly affect the strength of biomass. The objectives of this study are to understand the mechanism by which torrefaction improves the grindability of biomass and discuss suitable temperatures for thermal pretreatment for co-gasification/co-firing of biomass and coal. Wild cherry wood was selected as the model for this study. Samples were prepared by sawing a single tangential section from the heartwood and cutting it into eleven pieces. The samples were consecutively heated at 220, 260, 300, 350, 450 and 550⁰C for 0.5 hr under flowing nitrogen in a tube furnace. Untreated and treated samples were characterized for physical properties (color, dimensions and weight), microstructural changes by SEM, and cell wall composition changes and thermal behaviors by TGA and DSC. The morphology of the wood remained intact through the treatment range but the cell walls were thinner. Thermal treatments were observed to decompose the cell wall components. Hemicellulose decomposed over the range of ~200 to 300⁰C and resulted in weakening of the cell walls and subsequently improved grindability. Furthermore, wood samples treated above 300⁰C lost more than 39% in mass. Therefore, thermal pretreatment above the hemicelluloses decomposition temperature but below 300⁰C is probably sufficient to

Tight binding simulation study on zigzag single-walled carbon nanotubes

Science.gov (United States)

Sharma, Deepa; Jaggi, Neena; Gupta, Vishu

2018-01-01

Tight binding simulation studies using the density functional tight binding (DFTB) model have been performed on various zigzag single-walled carbon-nanotubes (SWCNTs) to investigate their electronic properties using DFTB module of the Material Studio Software version 7.0. Various combinations of different eigen-solvers and charge mixing schemes available in the DFTB Module have been tried to chalk out the electronic structure. The analytically deduced values of the bandgap of (9, 0) SWCNT were compared with the experimentally determined value reported in the literature. On comparison, it was found that the tight binding approximations tend to drastically underestimate the bandgap values. However, the combination of Anderson charge mixing method with standard eigensolver when implemented using the smart algorithm was found to produce fairly close results. These optimized model parameters were then used to determine the band structures of various zigzag SWCNTs. (9, 0) Single-walled Nanotube which is extensively being used for sensing NH3, CH4 and NO2 has been picked up as a reference material since its experimental bandgap value has been reported in the literature. It has been found to exhibit a finite energy bandgap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies. Such simulation studies if used intelligently prove to be immensely useful to the material scientists as they not only save time and effort but also pave the way to new experiments by making valuable predictions.

Radiation Protection Using Single-Wall Carbon Nanotube Derivatives

Science.gov (United States)

Tour, James M.; Lu, Meng; Lucente-Schultz, Rebecca; Leonard, Ashley; Doyle, Condell Dewayne; Kosynkin, Dimitry V.; Price, Brandi Katherine

2011-01-01

This invention is a means of radiation protection, or cellular oxidative stress mitigation, via a sequence of quenching radical species using nano-engineered scaffolds, specifically single-wall carbon nanotubes (SWNTs) and their derivatives. The material can be used as a means of radiation protection by reducing the number of free radicals within, or nearby, organelles, cells, tissue, organs, or living organisms, thereby reducing the risk of damage to DNA and other cellular components (i.e., RNA, mitochondria, membranes, etc.) that can lead to chronic and/or acute pathologies, including but not limited to cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. In addition, this innovation could be used as a prophylactic or antidote for accidental radiation exposure, during high-altitude or space travel where exposure to radiation is anticipated, or to protect from exposure from deliberate terrorist or wartime use of radiation- containing weapons.

Incremental value of regional wall motion analysis immediately after exercise for the detection of single-vessel coronary artery disease. Study by separate acquisition, dual-isotope ECG-gated single-photon emission computed tomography

International Nuclear Information System (INIS)

Yoda, Shunichi; Sato, Yuichi; Matsumoto, Naoya; Tani, Shigemasa; Takayama, Tadateru; Uchiyama, Takahisa; Saito, Satoshi

2005-01-01

Although the detection of wall motion abnormalities gives incremental value to myocardial perfusion single-photon emission computed tomography (SPECT) in the diagnosis of extensive coronary artery disease (CAD) and high-grade single-vessel CAD, whether or not it is useful in the diagnosis of mild, single-vessel CAD has not been studied previously. Separate acquisition, dual isotope electrocardiogram (ECG)-gated SPECT was performed in 97 patients with a low likelihood of CAD (Group 1) and 46 patients with single-vessel CAD (Group 2). Mild CAD was defined by stenosis of 50-75% (Group 2a, n=22) and moderate to severe CAD was defined by stenosis ≥76% (Group 2b, n=24). Myocardial perfusion and wall motion were graded by a 5 point-scale, 20-segment model. The sensitivity of myocardial perfusion alone was 50% for Group 2a, 83% for Group 2b and 67% for Group 2 as a whole. The overall specificity was 90%. When the wall motion analysis was combined, the sensitivity was increased to 82% in Group 2a and 92% in Group 2b. The ability to detect a wall motion abnormality immediately after exercise gives incremental diagnostic value to myocardial perfusion SPECT in the identification of mild, single-vessel CAD. (author)

Impact assessment of the forest fires on Oarai Research and Development Center Waste Treatment Facility

International Nuclear Information System (INIS)

Shimomura, Yusuke; Kitamura, Ryoichi; Hanari, Akira; Sato, Isamu

2016-03-01

In response to new standards for regulating waste treatment facility ('new regulatory standards'; December 18, 2013 enforcement), it was carried out impact assessment of forest fires on the Waste Treatment Facility existed in Oarai Research and Development Center of Japan Atomic Energy Agency. At first, a fire spread scenario of forest fires was assumed. The intensity of forest fires was evaluated from field surveys, forest fire evaluation models and so on. As models of forest fire intensity evaluation, Rothermel Model and Canadian Forest Fire Behavior Prediction (FBP) System were used. Impact assessment of radiant heat to the facility was carried out, and temperature change of outer walls for the assumed forest fires was estimated. The outer wall temperature of facility was estimated around 160degC at the maximum, it was revealed that it doesn't reach allowable temperature limit. Consequently, it doesn't influence the strength of concrete. In addition, a probability of fire breach was estimated to be about 20%. This report illustrates an example of evaluation of forest fires for the new regulatory standards through impact assessment of the forest fires on the Waste Treatment Facility. (author)

The Effects of Single-Wall Carbon Nanotubes on the Shear Piezoelectricity of Biopolymers

Science.gov (United States)

Lovell, Conrad; Fitz-Gerald, James M.; Harrison, Joycelyn S.; Park, Cheol

2008-01-01

Shear piezoelectricity was investigated in a series of composites consisting of increased loadings of single-wall carbon nanotubes (SWCNTs) in poly (gamma-benzyl-L-glutamate), or PBLG. The effects of the SWCNTs on this material property in PBLG will be discussed. Their influence on the morphology of the polymer (degree of orientation and crystallinity), and electrical and dielectric properties of the composite will be reported

DNA-templated synthesis of Pt nanoparticles on single-walled carbon nanotubes.

Science.gov (United States)

Dong, Lifeng

2009-11-18

A series of electron microscopy characterizations demonstrate that single-stranded deoxyribonucleic acid (ssDNA) can bind to nanotube surfaces and disperse bundled single-walled carbon nanotubes (SWCNTs) into individual tubes. The ssDNA molecules on the nanotube surfaces demonstrate various morphologies, such as aggregated clusters and spiral wrapping around a nanotube with different pitches and spaces, indicating that the morphology of the SWCNT/DNA hybrids is not related solely to the base sequence of the ssDNA or the chirality or the diameter of the nanotubes. In addition to serving as a non-covalent dispersion agent, the ssDNA molecules bonded to the nanotube surface can provide addresses for localizing Pt(II) complexes along the nanotubes. The Pt nanoparticles obtained by a reduction of the Pt2+-DNA adducts are crystals with a size of direct ethanol/methanol fuel cells and nanoscale electronics.

Electrical transport through single-wall carbon nanotube-anodic aluminum oxide-aluminum heterostructures

International Nuclear Information System (INIS)

Kukkola, Jarmo; Rautio, Aatto; Sala, Giovanni; Pino, Flavio; Toth, Geza; Leino, Anne-Riikka; Maeklin, Jani; Jantunen, Heli; Uusimaeki, Antti; Kordas, Krisztian; Gracia, Eduardo; Terrones, Mauricio; Shchukarev, Andrey; Mikkola, Jyri-Pekka

2010-01-01

Aluminum foils were anodized in sulfuric acid solution to form thick porous anodic aluminum oxide (AAO) films of thickness ∼6 μm. Electrodes of carboxyl-functionalized single-wall carbon nanotube (SWCNT) thin films were inkjet printed on the anodic oxide layer and the electrical characteristics of the as-obtained SWCNT-AAO-Al structures were studied. Nonlinear current-voltage transport and strong temperature dependence of conduction through the structure was measured. The microstructure and chemical composition of the anodic oxide layer was analyzed using transmission and scanning electron microscopy as well as x-ray photoelectron spectroscopy. Schottky emission at the SWCNT-AAO and AAO-Al interfaces allowed by impurity states in the anodic aluminum oxide film together with ionic surface conduction on the pore walls of AAO gives a reasonable explanation for the measured electrical conduction. Calcined AAO is proposed as a dielectric material for SWCNT-field effect transistors.

Failure analysis of the boiler water-wall tube

Directory of Open Access Journals (Sweden)

S.W. Liu

2017-10-01

Full Text Available Failure analysis of the boiler water-wall tube is presented in this work. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy were carried out. Tube wall thickness measurements were performed on the ruptured tube. The fire-facing side of the tube was observed to have experienced significant wall thinning. The composition of the matrix material of the tube meets the requirements of the relevant standards. Microscopic examinations showed that the spheroidization of pearlite is not very obvious. The failure mechanism is identified as a result of the significant localized wall thinning of the boiler water-wall tube due to oxidation.

Determination of the displacement cross section in single-walled carbon nanotubes under gamma irradiation

International Nuclear Information System (INIS)

Leyva, A.; Pinnera, I.; Cruz, C.; Abreu, Y.; Leyva, D.

2009-01-01

Using the threshold energy value reported in literature for C atoms in single-walled carbon nanotube and taking into account the McKinley-Feshbach approach, the effective atomic displacement cross-section in nanotubes exposed to the gamma rays was estimated. In this calculation the Kinchin-Pease approximation for the damage function was considered. (Author)

The Italian National Guidelines for the fire safety of facades

Directory of Open Access Journals (Sweden)

Lamberto Mazziotti

2013-11-01

Full Text Available Traditionally, the facades' design buildings where once only focused on architectural or aesthetic purposes (in addition, of course, of whether protective issues. Nowadays, thanks to the technological development of the construction works and the use of new types of materials, the facades' design should also address fire safety related aspects. In Europe and especially in Italy – where the types of building façades are built with windows of small surface and natural stone coverings – the green building/sustainability movement has resulted in the development of new concepts in facade or curtain wall design that intended to enhance the energy efficiency of building façades. These new building surfaces are covered by extensive panelling fitted with insulating materials or by wide glass surfaces, capable of carry out the most diverse purposes including, just to name a few: energy reduction, climate comfort, recovery of electricity through photovoltaic panels that convert sunlight into electricity, large space for advertising purpose. One of the main fire safety goal for a building design is to restrict the vertical fire spread so that the smoke and flames are limited to the fire origin floor. The new building façade and curtain wall topologies could overwhelms concerns for fire safety, therefore the Italian National fire service has released a Fire Code Guideline in order to address the fire safety design for an high rise building façade. This paper aims to show the guideline contents and the related fire safety façades concerns.

Design and performance of a skid-mounted portable compartment fire gas furnace and monitoring system

Directory of Open Access Journals (Sweden)

Mueller K.

2013-09-01

Full Text Available A custom, portable natural gas fire furnace was designed and constructed for use at the University of Notre Dame to experimentally investigate the out-of-plane behavior of full-scale reinforced concrete (RC bearing walls under fire. The unique aspects of this furnace allowed the application of large mechanical loads and non-contact optical response monitoring to be done while subjecting the wall to elevated temperatures. The performance of the experimental furnace, mechanical loading, and response monitoring system is reported using the results from the first two RC wall test specimens.

Formation of transition metal cluster adducts on the surface of single-walled carbon nanotubes: HRTEM studies

KAUST Repository

Kalinina, Irina V.

2014-01-01

We report the formation of chromium clusters on the outer walls of single-walled carbon nanotubes (SWNTs). The clusters were obtained by reacting purified SWNTs with chromium hexacarbonyl in dibutyl ether at 100°C. The functionalized SWNTs were characterized by thermogravimetic analysis, XPS, and high-resolution TEM. The curvature of the SWNTs and the high mobility of the chromium moieties on graphitic surfaces allow the growth of the metal clusters and we propose a mechanism for their formation. © 2014 Taylor and Francis Group, LLC.

Immunosensors Based on Single-Walled Carbon Nanotubes (SWCNT for the Detection of Deep Venous Thrombosis

Directory of Open Access Journals (Sweden)

Sondes BOURIGUA

2014-05-01

Full Text Available Thanks to their properties, Single-Walled carbon nanotubes (SWNT open a new way to the fabrication of Immunosensors with the particularity to amplify the response signal from antibody–antigen interaction and to improve the Immunosensors characteristics. In this context, two new impedimetric immunosensors were developed by immobilizing antibody on Single-Walled carbon, the later was immobilized following two ways the first consist of immobilizing the carbon nanotubes on a polypyrrole layer by adsorption and the second consist of functionalized gold with amino thiol and then immobilizing the carbon nanotubes with covalent binding. The electrical properties and the morphology of the immunosensors have been characterized respectively by Electrochemical Impedance Spectroscopy, cyclic voltammetry and Atomic Force Spectroscopy. A low detection limit for both immunosensors was determined as 1 pg/ml and linear ranges up to 10 ng/ml with polypyrrole and up to 100 ng/ml with amino thiol were obtained. Moreover, the studied Immunosensors exhibited high sensitivity, stability and reproducibility.

Charge transport in transparent single-wall carbon nanotube networks

International Nuclear Information System (INIS)

Jaiswal, Manu; Wang, Wei; Fernando, K A Shiral; Sun Yaping; Menon, Reghu

2007-01-01

We report the electric-field effects and magnetotransport in transparent networks of single-wall carbon nanotubes (SWNT). The temperature dependence of conductance of the network indicates a 2D Mott variable-range hopping (VRH) transport mechanism. Electric field and temperature are shown to have similar effects on the carrier hops and identical exponents for the conductance of the network are obtained from the high electric field and temperature dependences. A power-law temperature dependence with an exponent 3/2 for the threshold field is obtained and explained as a result of the competing contributions from electric field and phonons to the carrier hop. A negative magnetoresistance (MR) is observed at low temperatures, which arises from a forward interference scattering mechanism in the weak scattering limit, consistent with the VRH transport

Large work function difference driven electron transfer from electrides to single-walled carbon nanotubes

KAUST Repository

Menamparambath, Mini Mol; Park, Jong Ho; Yoo, Ho Sung; Patole, Shashikant P.; Yoo, Ji Beom; Kim, Sung Wng; Baik, Seunghyun

2014-01-01

V. Here we investigated charge transfer between two different types of electrides, [Ca2N]+·e- and [Ca 24Al28O64]4+·4e-, and single-walled carbon nanotubes (SWNTs) with a work function of 4.73-5.05 eV. [Ca2N]+·e- with open 2-dimensional electron layers

Economic assessment of single-walled carbon nanotube processes

Science.gov (United States)

Isaacs, J. A.; Tanwani, A.; Healy, M. L.; Dahlben, L. J.

2010-02-01

The carbon nanotube market is steadily growing and projected to reach 1.9 billion by 2010. This study examines the economics of manufacturing single-walled carbon nanotubes (SWNT) using process-based cost models developed for arc, CVD, and HiPco processes. Using assumed input parameters, manufacturing costs are calculated for 1 g SWNT for arc, CVD, and HiPco, totaling 1,906, 1,706, and 485, respectively. For each SWNT process, the synthesis and filtration steps showed the highest costs, with direct labor as a primary cost driver. Reductions in production costs are calculated for increased working hours per day and for increased synthesis reaction yield (SRY) in each process. The process-based cost models offer a means for exploring opportunities for cost reductions, and provide a structured system for comparisons among alternative SWNT manufacturing processes. Further, the models can be used to comprehensively evaluate additional scenarios on the economics of environmental, health, and safety best manufacturing practices.

Supercapacitance of Single-Walled Carbon Nanotubes-Polypyrrole Composites

Directory of Open Access Journals (Sweden)

Matei Raicopol

2013-01-01

Full Text Available The composites based on carbon nanotubes (CNTs and conducting polymers (CPs are promising materials for supercapacitor devices due to their unique nanostructure that combines the large pseudocapacitance of the CPs with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the CNTs. Here, we report a new electrochemical method to obtain polypyrrole (PPY/single-walled carbon nanotube (SWCNT composites. In the first step, the SWCNTs are covalently functionalized with monomeric units of pyrrole by esterification of acyl chloride functionalized SWCNTs and N-(6-hydroxyhexylpyrrole. In the second step, the PPY/SWCNTs composites are obtained by copolymerizing the pyrrole monomer with the pyrrole units grafted on SWCNTs surface using controlled potential electrolysis. The composites were further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed good electrochemical charge storage properties for the synthesized composites based on PPY and SWCNTs covalently functionalized with pyrrole units making them promising electrode materials for high power supercapacitors.

Economic assessment of single-walled carbon nanotube processes

Energy Technology Data Exchange (ETDEWEB)

Isaacs, J. A., E-mail: jaisaacs@coe.neu.ed [Northeastern University, NSF Center for High-rate Nanomanufacturing (United States); Tanwani, A. [Infojini Solutions Inc. (United States); Healy, M. L. [Babcock Power Inc. (United States); Dahlben, L. J. [Northeastern University, NSF Center for High-rate Nanomanufacturing (United States)

2010-02-15

The carbon nanotube market is steadily growing and projected to reach $1.9 billion by 2010. This study examines the economics of manufacturing single-walled carbon nanotubes (SWNT) using process-based cost models developed for arc, CVD, and HiPco processes. Using assumed input parameters, manufacturing costs are calculated for 1 g SWNT for arc, CVD, and HiPco, totaling $1,906, $1,706, and $485, respectively. For each SWNT process, the synthesis and filtration steps showed the highest costs, with direct labor as a primary cost driver. Reductions in production costs are calculated for increased working hours per day and for increased synthesis reaction yield (SRY) in each process. The process-based cost models offer a means for exploring opportunities for cost reductions, and provide a structured system for comparisons among alternative SWNT manufacturing processes. Further, the models can be used to comprehensively evaluate additional scenarios on the economics of environmental, health, and safety best manufacturing practices.

46 CFR 118.300 - Fire pumps.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Fire pumps. 118.300 Section 118.300 Shipping COAST GUARD... Fire pumps. (a) A self priming, power driven fire pump must be installed on each vessel. (b) On a..., the fire pump must be capable of delivering a single hose stream from the highest hydrant, through the...

The clinical meaning of gastric-wall hyperactivity observed on sestamibi cardiac single-photon emission computed tomography

Energy Technology Data Exchange (ETDEWEB)

Cote, C.; Dumont, M. [Centre Hospitalier Universitaire de Quebec, Dept. of Nuclear Medicine, Quebec, Quebec (Canada)]. E-mail: christian.cote@chuq.qc.ca

2004-06-01

To evaluate prospectively the incidence and clinical meaning, if any, of gastric-wall hyperactivity observed on sestamibi cardiac single-photon emission computed tomography (SPECT). This phenomenon is completely different from the well-known intraluminal gastric reflux of sestamibi. A group of 819 patients who underwent sestamibi cardiac SPECT was studied from January 2000 to October 2000. Gastric-wall activity was graded qualitatively. Only patients with gastric-wall activity near or equivalent to their heart activity were considered for subsequent analysis. The medical records of patient candidates were reviewed, and their family physicians were asked to respond to a questionnaire by telephone when further information was needed. We identified 13 patients with significant gastric-wall hyperactivity, which was more intense on rest images. Our review of the clinical data shows that all these patients were suffering from dyspepsia and were taking gastric medication. These 13 cases were assigned to 3 groups: gastroesophageal reflux, chronic functional dyspepsia and nonspecific gastritis. Significant gastric-wall hyperactivity is an infrequent observation on sestamibi cardiac SPECT. Our results indicate that the presence of significant gastric-wall hyperactivity is associated with dyspepsia. It is important to realize that this gastric-wall hyperactivity by its proximity to the inferior myocardial wall could in some circumstances lead to either false-negative or false-positive findings, representing a diagnostic problem. Although infrequent, this situation could be avoided by proper quality control, including a systematic review of the raw cine data before reading the images. (author)

Computational and experimental studies of the interaction between single-walled carbon nanotubes and folic acid

DEFF Research Database (Denmark)

Castillo, John J.; Rozo, Ciro E.; Castillo-León, Jaime

2013-01-01

Nlayered Integrated Molecular Orbital and Molecular Mechanics (B3LYP(6–31G(d):UFF)). The results confirmed that the interaction occurred via hydrogen bonding between protons of the glutamic moiety from folic acid and π electrons from the carbon nanotubes. The single-walled carbon nanotube-folic acid...

Firewalls in bee nests—survival value of propolis walls of wild Cape honeybee ( Apis mellifera capensis)

Science.gov (United States)

Tribe, Geoff; Tautz, Jürgen; Sternberg, Karin; Cullinan, Jenny

2017-04-01

The Cape bee is endemic to the winter rainfall region of South Africa where fires are an integral part of the ecology of the fynbos (heathland) vegetation. Of the 37 wild nests in pristine Peninsula Sandstone Fynbos in the Cape Point section of Table Mountain National Park that have been analyzed so far, only 22 could be accessed sufficiently to determine the existence of a propolis wall of which 68% had propolis walls which entirely enclosed their openings. The analysis of the 37 wild nests revealed that 78% occurred under boulders or in clefts within rocks, 11% in the ground, 8% in tree cavities, and 3% within shrubs. The analysis of 17 of these nests following a fire within the park revealed that the propolis walls materially protected the nests and retarded the fire with all the colonies surviving. The bees responded to the smoke by imbibing honey and retreating to the furthest recess of their nest cavity. The bees were required to utilize this honey for about 3 weeks after which fire-loving plants appeared and began flowering. Considerable resources were utilized in the construction of the propolis walls, which ranged in thickness from 1.5 to 40 mm (mean 5 mm). Its physical environment determines the nesting behavior of the Cape bee. The prolific use of propolis serves to insulate the nest from extremes of temperature and humidity, restricts entry, camouflages the nest, and acts as an effective fire barrier protecting nests established mostly under rocks in vegetation subjected to periodic fires.

Firewalls in bee nests-survival value of propolis walls of wild Cape honeybee (Apis mellifera capensis).

Science.gov (United States)

Tribe, Geoff; Tautz, Jürgen; Sternberg, Karin; Cullinan, Jenny

2017-04-01

The Cape bee is endemic to the winter rainfall region of South Africa where fires are an integral part of the ecology of the fynbos (heathland) vegetation. Of the 37 wild nests in pristine Peninsula Sandstone Fynbos in the Cape Point section of Table Mountain National Park that have been analyzed so far, only 22 could be accessed sufficiently to determine the existence of a propolis wall of which 68% had propolis walls which entirely enclosed their openings. The analysis of the 37 wild nests revealed that 78% occurred under boulders or in clefts within rocks, 11% in the ground, 8% in tree cavities, and 3% within shrubs. The analysis of 17 of these nests following a fire within the park revealed that the propolis walls materially protected the nests and retarded the fire with all the colonies surviving. The bees responded to the smoke by imbibing honey and retreating to the furthest recess of their nest cavity. The bees were required to utilize this honey for about 3 weeks after which fire-loving plants appeared and began flowering. Considerable resources were utilized in the construction of the propolis walls, which ranged in thickness from 1.5 to 40 mm (mean 5 mm). Its physical environment determines the nesting behavior of the Cape bee. The prolific use of propolis serves to insulate the nest from extremes of temperature and humidity, restricts entry, camouflages the nest, and acts as an effective fire barrier protecting nests established mostly under rocks in vegetation subjected to periodic fires.

Extinction properties of single-walled carbon nanotubes: Two-fluid model

Energy Technology Data Exchange (ETDEWEB)

Moradi, Afshin, E-mail: a.moradi@kut.ac.ir [Department of Basic Sciences, Kermanshah University of Technology, Kermanshah, Iran and Department of Nano Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran (Iran, Islamic Republic of)

2014-03-15

The extinction spectra of a single-walled carbon nanotube are investigated, within the framework of the vector wave function method in conjunction with the hydrodynamic model. Both polarizations of the incident plane wave (TE and TM with respect to the x-z plane) are treated. Electronic excitations on the nanotube surface are modeled by an infinitesimally thin layer of a two-dimensional electron gas represented by two interacting fluids, which takes into account the different nature of the σ and π electrons. Numerical results show that strong interaction between the fluids gives rise to the splitting of the extinction spectra into two peaks in quantitative agreement with the π and σ + π plasmon energies.

Confinement in single walled carbon nanotubes investigated by spectroscopic ellipsometry

International Nuclear Information System (INIS)

Battie, Y.; Jamon, D.; Lauret, J.S.; Gu, Q.; Gicquel-Guézo, M.; En Naciri, A.; Loiseau, A.

2014-01-01

Thick films of single walled carbon nanotubes (SWCNTs) with different diameter and chirality distributions are characterized by combining transmission electron microscopy and spectroscopic ellipsometry. The dependence of the dielectric function with the increase of the SWCNT diameter occurs with a drastic redshift of the S 11 , S 22 and M 11 transition energies. The transfer integral parameter γ 0 of SWCNT is also evaluated and analyzed. We demonstrate that parts of the optical properties of SWCNTs are attributed to a one dimensional confinement effect. - Highlights: • Ellipsometric measurements are performed on carbon nanotube thick films. • The complex dielectric functions of conventional carbon nanotubes are given. • Confinement effects explain the variations of dielectric function of nanotubes

A study on AFM manipulation of single-wall carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Tian Xiaojun; Dong Zaili; Yu Peng; Liu Zhu [State Key Lab. of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016 (China)], E-mail: xjtian@sia.cn

2009-09-01

As single-wall carbon nanotube (SWCNT) has special electrical and physical property, it can be used as excellent material to construct various nano electronic device. However, in the fabrication process, the modification of size, shape and even the electronic property, especially to the metallic SWCNT, is a key problem to be overcome. Here a modified nanomanipulation technology based on atomic force microscope (AFM) is utilized to perform various kinds of SWCNT manipulation, such as SWCNT separation, catalyst remove, continual nano buckles fabrication and even stretch to break, thus to modify the size, shape and eventually the electrical property of the SWCNT. In addition, the manipulation results are analyzed based on the mechanical mechanism.

Risk assessment of main control board fire using fire dynamics simulator

Energy Technology Data Exchange (ETDEWEB)

Kang, Dae Il, E-mail: dikang@kaeri.re.kr [KAERI, 1045 Daedeokdaero, Yuseong-Gu, Daejeon 305-353 (Korea, Republic of); Kim, Kilyoo; Jang, Seung-Cheol [KAERI, 1045 Daedeokdaero, Yuseong-Gu, Daejeon 305-353 (Korea, Republic of); Yoo, Seong Yeon [Chungnam National University, 79, Daehagro, Yuseong-Gu, Daejeon (Korea, Republic of)

2015-08-15

Highlights: • A decision tree for evaluating the risk of a main control board (MCB) fire was proposed to systematically determine the MCB fire scenarios. • Fire simulations using fire dynamics simulator (FDS) were performed to estimate the time to MCR abandonment. • Non-propagating and propagating fire scenarios were considered for fire simulations. • The current study indicates that the quantification of the MCB fire risk should address the propagating fire and non-propagating fire scenarios if the MCB has no internal barriers between the panels. - Abstract: This paper presents the process and results of a risk assessment for a main control board (MCB) fire using fire dynamics simulator (FDS). A decision tree for evaluating the risk of a MCB fire was proposed to systematically determine the MCB fire scenarios, and fire simulations using FDS were performed to estimate the time to MCR abandonment. As a reference NPP for this study, Hanul unit 3 in Korea was selected and its core damage frequency (CDF) owing to the MCB fire was quantified. Two types of fire scenarios were considered for fire simulations: non-propagating fire scenarios occurring within a single MCB panel and propagating fire scenarios spreading from one control panel to the adjacent panels. Further, the fire scenarios were classified into fires with and without a heating, ventilation, and air conditioning system (HVACS). The fire simulation results showed that the major factor causing the MCR evacuation was the optical density irrelevant to the availability of the HVACS. The risk assessment results showed that the abandonment fire scenario risk was less than the non-abandonment fire scenario risk and the propagating fire scenario risk was greater than the non-propagating fire scenario risk.

Risk assessment of main control board fire using fire dynamics simulator

International Nuclear Information System (INIS)

Kang, Dae Il; Kim, Kilyoo; Jang, Seung-Cheol; Yoo, Seong Yeon

2015-01-01

Highlights: • A decision tree for evaluating the risk of a main control board (MCB) fire was proposed to systematically determine the MCB fire scenarios. • Fire simulations using fire dynamics simulator (FDS) were performed to estimate the time to MCR abandonment. • Non-propagating and propagating fire scenarios were considered for fire simulations. • The current study indicates that the quantification of the MCB fire risk should address the propagating fire and non-propagating fire scenarios if the MCB has no internal barriers between the panels. - Abstract: This paper presents the process and results of a risk assessment for a main control board (MCB) fire using fire dynamics simulator (FDS). A decision tree for evaluating the risk of a MCB fire was proposed to systematically determine the MCB fire scenarios, and fire simulations using FDS were performed to estimate the time to MCR abandonment. As a reference NPP for this study, Hanul unit 3 in Korea was selected and its core damage frequency (CDF) owing to the MCB fire was quantified. Two types of fire scenarios were considered for fire simulations: non-propagating fire scenarios occurring within a single MCB panel and propagating fire scenarios spreading from one control panel to the adjacent panels. Further, the fire scenarios were classified into fires with and without a heating, ventilation, and air conditioning system (HVACS). The fire simulation results showed that the major factor causing the MCR evacuation was the optical density irrelevant to the availability of the HVACS. The risk assessment results showed that the abandonment fire scenario risk was less than the non-abandonment fire scenario risk and the propagating fire scenario risk was greater than the non-propagating fire scenario risk

Transverse mechanical properties of cell walls of single living plant cells probed by laser-generated acoustic waves.

Science.gov (United States)

Gadalla, Atef; Dehoux, Thomas; Audoin, Bertrand

2014-05-01

Probing the mechanical properties of plant cell wall is crucial to understand tissue dynamics. However, the exact symmetry of the mechanical properties of this anisotropic fiber-reinforced composite remains uncertain. For this reason, biologically relevant measurements of the stiffness coefficients on individual living cells are a challenge. For this purpose, we have developed the single-cell optoacoustic nanoprobe (SCOPE) technique, which uses laser-generated acoustic waves to probe the stiffness, thickness and viscosity of live single-cell subcompartments. This all-optical technique offers a sub-micrometer lateral resolution, nanometer in-depth resolution, and allows the non-contact measurement of the mechanical properties of live turgid tissues without any assumption of mechanical symmetry. SCOPE experiments reveal that single-cell wall transverse stiffness in the direction perpendicular to the epidermis layer of onion cells is close to that of cellulose. This observation demonstrates that cellulose microfibrils are the main load-bearing structure in this direction, and suggests strong bonding of microfibrils by hemicelluloses. Altogether our measurement of the viscosity at high frequencies suggests that the rheology of the wall is dominated by glass-like dynamics. From a comparison with literature, we attribute this behavior to the influence of the pectin matrix. SCOPE's ability to unravel cell rheology and cell anisotropy defines a new class of experiments to enlighten cell nano-mechanics.

Microwave-induced electrophilic addition of single-walled carbon nanotubes with alkylhalides

Energy Technology Data Exchange (ETDEWEB)

Xu Yang [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Wang Xianbao [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Ministry-of-Education, Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University, Wuhan 430062 (China)], E-mail: wxb@hubu.edu.cn; Tian Rong; Li Shaoqing; Wan Li; Li Mingjian; You Haijun; Li Qin [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Wang Shimin [Faculty of Materials Science and Engineering, Hubei University, Wuhan 430062 (China); Ministry-of-Education, Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University, Wuhan 430062 (China)

2008-02-15

We report the microwave-induced electrophilic addition of single-walled carbon nanotubes (SWNTs) with alkylhalides using Lewis acid as a catalyst followed by hydrolysis. The reaction results in the attachment of alkyl and hydroxyl groups to the surface of the nanotubes. This rapid and high-energy microwave radiation is found to be highly efficient for this reaction, which only needs as low as several minutes. The resulting nanotubes were characterized with FTIR, UV-vis-NIR, Raman, TGA, TEM and AFM. It demonstrates that iodo-alkanes show higher reaction activity with SWNTs than chloro- and bromo-alkanes.

The sodium fire tests performed in the FAUNA facility on up to 12m2 fire areas

International Nuclear Information System (INIS)

Cherdron, W.; Jordan, S.

1983-08-01

The FAUNA test facility started operation in 1979. It serves to investigate large area sodium fires in closed containments and to study the generation, behaviour and removal of sodium fire aerosols. In this report, the experimental results of the 6 sodium pool fires are described which were performed with up to 500 kg of sodium in fire pans of 2 m 2 , 5 m 2 and 12 m 2 surface area, respectively. Both, the thermodynamic data and the data of the reaction kinetics of the fires were determined. In addition, the behaviour of the released aerosols during and after the fire was studied. On the basis of measurements of the temperature profiles at various levels above the fire areas it was shown that the convective flows above fire areas of different sizes in closed containments differ markedly and, obviously, exert an influence on the development of the fire and the release of particles. Whilst in rather small fires the gas above the pan rises as in a chimney and flows back on the walls, no chimney effect can be observed in a large pool fire. In rather large fires higher burning rates and aerosol release rates were observed. Some meters above the fire area temperatures around 300-400 0 C, temporarily even up to 700 0 C, were measured. The tests F5 and F6 were performed above all to observe the fire behaviour in terms of thermodynamics and reaction kinetics in a fully closed containment. (orig./RW) [de

Polarized excitons and optical activity in single-wall carbon nanotubes

Science.gov (United States)

Chang, Yao-Wen; Jin, Bih-Yaw

2018-05-01

The polarized excitons and optical activity of single-wall carbon nanotubes (SWNTs) are studied theoretically by π -electron Hamiltonian and helical-rotational symmetry. By taking advantage of the symmetrization, the single-particle energy and properties of a SWNT are characterized with the corresponding helical band structure. The dipole-moment matrix elements, magnetic-moment matrix elements, and the selection rules can also be derived. Based on different selection rules, the optical transitions can be assigned as the parallel-polarized, left-handed circularly-polarized, and right-handed circularly-polarized transitions, where the combination of the last two gives the cross-polarized transition. The absorption and circular dichroism (CD) spectra are simulated by exciton calculation. The calculated results are well comparable with the reported measurements. Built on the foundation, magnetic-field effects on the polarized excitons and optical activity of SWNTs are studied. Dark-bright exciton splitting and interband Faraday effect in the CD spectrum of SWNTs under an axial magnetic field are predicted. The Faraday rotation dispersion can be analyzed according to the selection rules of circular polarizations and the helical band structure.

Hydrogen adsorption on metal-organic frameworks (MOFs) and single-walled carbon nanotubes (SWNTs)

Energy Technology Data Exchange (ETDEWEB)

Poirier, E.; Chahine, R.; Benard, P.; Lafi, L.; Dorval-Douville, G.; Chandonia, P.-A. [Univ. du Quebec a Trois-Rivieres, Inst. de recherche sur l' hydrogene, Trois-Rivieres, Quebec (Canada)]. E-mail: Lyubov.Lafi@uqtr.ca

2006-07-01

'Full text:' In recent years, several novel carbon-based microporous materials such as single-walled carbon nanotubes (SWNTs) and metal-organic frameworks (MOFs) have been proposed as promising adsorbents for hydrogen. Hydrogen adsorption measurements on Al-, Cr- and Zn-based metal-organic frameworks (MOFs) and single-walled carbon nanotubes (SWNTs) are presented. The measurements were performed at temperatures ranging from 77 to 300K and pressures up to 50 atm using a volumetric approach. The maximum excess adsorption at 77K ranges from 2,8 to 3,9 wt % for the MOFs and from 1,5 to 2,5 wt % for the SWNTs. These values are reached at pressures below 40 atm. At room temperature and 40 atm, modest amounts of hydrogen are adsorbed (< 0,4 wt %). A Dubinin-Astakhov (DA) approach is used to investigate the measured adsorption isotherms and retrieve energetic and structural parameters. The adsorption enthalpy averaged over filling is found to be about 2,9 kJ/mol for the MOF-5 and about 3,6 - 4,2 kJ/mol for SWNTs. The uptake of hydrogen on SWNTs and MOF-5 appears to be due to physisorption and can be described, through the DA-model, by a traditional theory of micropore filling. (author)

Novel strategy for diameter-selective separation and functionalization of single-wall carbon nanotubes.

Science.gov (United States)

Tromp, R M; Afzali, A; Freitag, M; Mitzi, D B; Chen, Zh

2008-02-01

The problem of separating single-wall carbon nanotubes (CNTs) by diameter and/or chirality is one of the greatest impediments toward the widespread application of these promising materials in nanoelectronics. In this paper, we describe a novel physical-chemical method for diameter-selective CNT separation that is both simple and effective and that allows up-scaling to large volumes at modest cost. Separation is based on size-selective noncovalent matching of an appropriate anchor molecule to the wall of the CNT, enabling suspension of the CNTs in solvents in which they would otherwise not be soluble. We demonstrate size-selective separation in the 1-2 nm diameter range using easily synthesized oligo-acene adducts as a diameter-selective molecular anchor. CNT field effect transistors fabricated from diameter-selected CNTs show markedly improved electrical properties as compared to nonselected CNTs.

Indium tin oxide-rod/single walled carbon nanotube based transparent electrodes for ultraviolet light-emitting diodes

International Nuclear Information System (INIS)

Yun, Min Ju; Kim, Hee-Dong; Kim, Kyeong Heon; Sung, Hwan Jun; Park, Sang Young; An, Ho-Myoung; Kim, Tae Geun

2013-01-01

In this paper, we report a transparent conductive oxide electrode scheme working for ultraviolet light-emitting diodes based on indium tin oxide (ITO)-rod and a single walled carbon nanotube (SWCNT) layer. We prepared four samples with ITO-rod, SWCNT/ITO-rod, ITO-rod/SWCNT, and SWCNT/ITO-rod/SWCNT structures for comparison. As a result, the sample with SWCNT/ITO-rod/SWCNT structures showed the highest transmittance over 90% at 280 nm and the highest Ohmic behavior (with sheet resistance of 5.33 kΩ/□) in the current–voltage characteristic curves. - Highlights: • Transparent conductive oxide (TCO) electrodes are proposed for UV light-emitting diodes. • These TCO electrodes are based on evaporated indium tin oxide (ITO)-rods. • Single walled carbon nanotube (SWCNT) layers are used as a current spreading layer. • The proposed TCO electrode structures show more than 90% transmittance at 280 nm

Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

Energy Technology Data Exchange (ETDEWEB)

Weber, Jessica E. [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Pillai, Shreekumar [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States); Ram, Manoj Kumar, E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Singh, Shree R. [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States)

2011-07-20

Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

Diameter modulation of vertically aligned single-walled carbon nanotubes.

Science.gov (United States)

Xiang, Rong; Einarsson, Erik; Murakami, Yoichi; Shiomi, Junichiro; Chiashi, Shohei; Tang, Zikang; Maruyama, Shigeo

2012-08-28

We demonstrate wide-range diameter modulation of vertically aligned single-walled carbon nanotubes (SWNTs) using a wet chemistry prepared catalyst. In order to ensure compatibility to electronic applications, the current minimum mean diameter of 2 nm for vertically aligned SWNTs is challenged. The mean diameter is decreased to about 1.4 nm by reducing Co catalyst concentrations to 1/100 or by increasing Mo catalyst concentrations by five times. We also propose a novel spectral analysis method that allows one to distinguish absorbance contributions from the upper, middle, and lower parts of a nanotube array. We use this method to quantitatively characterize the slight diameter change observed along the array height. On the basis of further investigation of the array and catalyst particles, we conclude that catalyst aggregation-rather than Ostwald ripening-dominates the growth of metal particles.

Improving the Sound Pressure Level of Two-Dimensional Audio Actuators by Coating Single-Walled Carbon Nanotubes on Piezoelectric Films.

Science.gov (United States)

Um, Keehong

2015-10-01

As devices for amplifying or transforming electronic signals into audible signals through electromechanical operations, acoustic actuators in the form of loudspeakers are usually solid structures in three dimensional space. Recently there has been increasing demand for mobile electronic devices, such as mobile phones, to become smaller, thinner, and lighter. In contrast to a three dimensional audio system with magnets, we have invented a new type of flexible two dimensional device by utilizing the reverse piezoelectric effect in certain piezoelectric materials. Crystalline piezoelectric materials show electromechanical interaction between the mechanical state and the electrically-charged state. The piezoelectric effect is a reversible process in that materials exhibiting the direct piezoelectric effect (the internal generation of electrical charge resulting from an applied mechanical force) also exhibit the reverse piezoelectric effect (the internal generation of a mechanical strain resulting from an applied electrical field). We have adopted the plasma surface treatment in order to put coating materials on the surface of piezoelectric film. We compared two kinds of coating material, indium tin oxide and single-walled carbon nanotube, and found that single-walled carbon nanotube shows better performance. The results showed improvement of output power in a wider range of operating frequency; for the surface resistance of 0.5 kΩ/square, the single-walled CNT shows the range of operating frequency to be 0.75-17.5 kHz, but ITO shows 2.5-13.4 kHz. For the surface resistance of 1 kΩ/square, single-walled CNT shows the range of operating frequency to be 0.81-17 kHz, but ITO shows it cannot generate audible sound.

Analysis of fire protection in nuclear power plants

International Nuclear Information System (INIS)

Hosser, D.; Schneider, U.

1982-01-01

Regulations and test specifications for fire prevention in nuclear power plants are presented as well as the fire protection measures in a newly constructed nuclear power plant. Although the emphasis is placed differently, all rules are based on the following single measures: Fire prevention, fire detection, fire fighting, fire checking, attack, flight, and rescue, organisational measures. (orig./GL) [de

The Performance of Calcium Silicate Board Partition Fireproof Drywall Assembly with Junction Box under Fire

Directory of Open Access Journals (Sweden)

Yinuo Wang

2015-01-01

Full Text Available This study uses a metal stud partition fireproof drywall measuring 83 mm in thickness as a test specimen to explore the impact of an embedded junction box on the firefighting performance of the wall through one time of standard fire test on a 300 cm × 300 cm area and five times of standard fire test on a 120 cm × 120 cm area. The results show that the quality of calcium silicate board plays a big role in the fireproof effectiveness. The embedded junction box located on the backside of the fire can reduce the effectiveness of the wall, especially the area above the socket. The thickness of rock wool may increase the performance, but in a limited rate. External junction box may not impact the fireproofing performance of the wall but it still possesses some safety risks. An embedded junction box measuring 101 × 55 mm could already damage the fire compartment, and in reality there may be more complicated situations that should be noted and improved.

Prevention of cable fires in nuclear power plants

International Nuclear Information System (INIS)

Murota, George; Yajima, Kazuo

1979-01-01

Nuclear power generation is indispensable to secure required electric power, therefore double or triple safety measures are necessary to prevent serious accidents absolutely. As for the countermeasures to cable fires, interest grew rapidly with the fire in Browns Ferry Power Station in USA in 1975 as the turning point, because multi-strand grouped cables caused to promote the spread of fire. In Japan, also the fire prevention measures for wires and cables were more strengthened, and the measures for preventing the spread of cable fires with the agent preventing the spread of fires have occupied the important position. When multi-strand cables are ignited by some cause, the fire spreads with very large combustion force along wirings to other rooms and installations, and electric systems are broken down. The harmful corrosive gas generated from the burning coating materials of cables diffuses very quickly. In nuclear power stations, the cables which are very hard to burn are adopted, fire prevention sections are established positively, the fire-resisting capability of fire prevention barriers is reviewed, and fire-resisting and smoke-preventing treatments are applied to the parts where cables penetrate walls, floors or ceilings. The paint and the sealing material which prevent the spread of fires are introduced. (Kako, I.)

Pool fires in a large scale ventilation system

International Nuclear Information System (INIS)

Smith, P.R.; Leslie, I.H.; Gregory, W.S.; White, B.

1991-01-01

A series of pool fire experiments was carried out in the Large Scale Flow Facility of the Mechanical Engineering Department at New Mexico State University. The various experiments burned alcohol, hydraulic cutting oil, kerosene, and a mixture of kerosene and tributylphosphate. Gas temperature and wall temperature measurements as a function of time were made throughout the 23.3m 3 burn compartment and the ducts of the ventilation system. The mass of the smoke particulate deposited upon the ventilation system 0.61m x 0.61m high efficiency particulate air filter for the hydraulic oil, kerosene, and kerosene-tributylphosphate mixture fires was measured using an in situ null balance. Significant increases in filter resistance were observed for all three fuels for burning time periods ranging from 10 to 30 minutes. This was found to be highly dependent upon initial ventilation system flow rate, fuel type, and flow configuration. The experimental results were compared to simulated results predicted by the Los Alamos National Laboratory FIRAC computer code. In general, the experimental and the computer results were in reasonable agreement, despite the fact that the fire compartment for the experiments was an insulated steel tank with 0.32 cm walls, while the compartment model FIRIN of FIRAC assumes 0.31 m thick concrete walls. This difference in configuration apparently caused FIRAC to consistently underpredict the measured temperatures in the fire compartment. The predicted deposition of soot proved to be insensitive to ventilation system flow rate, but the measured values showed flow rate dependence. However, predicted soot deposition was of the same order of magnitude as measured soot deposition

Means of regulating combustible materials and products in external walls

Directory of Open Access Journals (Sweden)

Mikkola Esko

2016-01-01

Full Text Available This report presents proposals for defining means of regulating the use of combustible materials and products in external walls. Required protections are based on the quantities of fire loads and their contribution to fire development. The study is based on life safety and protection of property priorities taking into account reaction to fire classes related to different types of fire loads and fire compartmentation requirements of the adjacent spaces of concern. The proposals include the following main principles in relation to fire-separation requirements: In case of internal fire exposure the protective structure for combustible building parts needs to meet at least half of the fire-separating requirement for the compartment of concern. In case of external fire exposure the protection time requirement can be 15 minutes less than for the internal protection. The proposals are applicable for residential buildings and offices. In case of buildings with longer evacuation times more stringent requirement levels may be considered. For verification of protection performance of fire loads it is proposed to use existing standardized test methods (fire protection ability (K classes and fire-separating function (EI classes validated methods of calculation and/or large scale fire testing.

The influence of engine speed and load on the heat transfer between gases and in-cylinder walls at fired and motored conditions of an IDI diesel engine

International Nuclear Information System (INIS)

Sanli, Ali; Ozsezen, Ahmet N.; Kilicaslan, Ibrahim; Canakci, Mustafa

2008-01-01

In this study, the heat transfer characteristics between gases and in-cylinder walls at fired and motored conditions in a diesel engine were investigated by using engine data obtained experimentally. For this investigation, a four-cylinder, indirect injection (IDI) diesel engine was tested under different engine speeds and loads. The heat transfer coefficient was calculated by using Woschni expression correlated for the IDI diesel engines, and also using Annand and Hohenberg expressions. The temperature of in-cylinder gases were determined from a basic model based on the first law of thermodynamics after measuring in-cylinder pressure experimentally. The results show that the heat transfer characteristics of the IDI diesel engine strongly depend on the engine speed and load as a function of crank angle at fired and motored conditions

The influence of engine speed and load on the heat transfer between gases and in-cylinder walls at fired and motored conditions of an IDI diesel engine

Energy Technology Data Exchange (ETDEWEB)

Sanli, Ali; Kilicaslan, Ibrahim [Department of Mechanical Education, Kocaeli University, 41380 Izmit (Turkey); Ozsezen, Ahmet N.; Canakci, Mustafa [Department of Mechanical Education, Kocaeli University, 41380 Izmit (Turkey); Alternative Fuels R and D Center, Kocaeli University, 41040 Izmit (Turkey)

2008-08-15

In this study, the heat transfer characteristics between gases and in-cylinder walls at fired and motored conditions in a diesel engine were investigated by using engine data obtained experimentally. For this investigation, a four-cylinder, indirect injection (IDI) diesel engine was tested under different engine speeds and loads. The heat transfer coefficient was calculated by using Woschni expression correlated for the IDI diesel engines, and also using Annand and Hohenberg expressions. The temperature of in-cylinder gases were determined from a basic model based on the first law of thermodynamics after measuring in-cylinder pressure experimentally. The results show that the heat transfer characteristics of the IDI diesel engine strongly depend on the engine speed and load as a function of crank angle at fired and motored conditions. (author)

Structural anisotropy of magnetically aligned single wall carbon nanotube films

International Nuclear Information System (INIS)

Smith, B. W.; Benes, Z.; Luzzi, D. E.; Fischer, J. E.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2000-01-01

Thick films of aligned single wall carbon nanotubes and ropes have been produced by filtration/deposition from suspension in strong magnetic fields. We measured mosaic distributions of rope orientations in the film plane, for samples of different thicknesses. For an ∼1 μm film the full width at half maximum (FWHM) derived from electron diffraction is 25 degree sign -28 degree sign . The FWHM of a thicker film (∼7 μm) measured by x-ray diffraction is slightly broader, 35±3 degree sign . Aligned films are denser than ordinary filter-deposited ones, and much denser than as-grown material. Optimization of the process is expected to yield smaller FWHMs and higher densities. (c) 2000 American Institute of Physics

Ultraclean individual suspended single-walled carbon nanotube field effect transistor

Science.gov (United States)

Liu, Siyu; Zhang, Jian; Nshimiyimana, Jean Pierre; Chi, Xiannian; Hu, Xiao; Wu, Pei; Liu, Jia; Wang, Gongtang; Sun, Lianfeng

2018-04-01

In this work, we report an effective technique of fabricating ultraclean individual suspended single-walled carbon nanotube (SWNT) transistors. The surface tension of molten silver is utilized to suspend an individual SWNT between a pair of Pd electrodes during annealing treatment. This approach avoids the usage and the residues of organic resist attached to SWNTs, resulting ultraclean SWNT devices. And the resistance per micrometer of suspended SWNTs is found to be smaller than that of non-suspended SWNTs, indicating the effect of the substrate on the electrical properties of SWNTs. The ON-state resistance (˜50 kΩ), mobility of 8600 cm2 V-1 s-1 and large on/off ratio (˜105) of semiconducting suspended SWNT devices indicate its advantages and potential applications.

Single-walled carbon nanotube networks for flexible and printed electronics

International Nuclear Information System (INIS)

Zaumseil, Jana

2015-01-01

Networks of single-walled carbon nanotubes (SWNTs) can be processed from solution and have excellent mechanical properties. They are highly flexible and stretchable. Depending on the type of nanotubes (semiconducting or metallic) they can be used as replacements for metal or transparent conductive oxide electrodes or as semiconducting layers for field-effect transistors (FETs) with high carrier mobilities. They are thus competitive alternatives to other solution-processable materials for flexible and printed electronics. This review introduces the basic properties of SWNTs, current methods for dispersion and separation of metallic and semiconducting SWNTs and techniques to deposit and pattern dense networks from dispersion. Recent examples of applications of carbon nanotubes as conductors and semiconductors in (opto-)electronic devices and integrated circuits will be discussed. (paper)

Magnetic and electronic properties of single-walled Mo2C nanotube: a first-principles study

Science.gov (United States)

Jalil, Abdul; Sun, Zhongti; Wang, Dayong; Wu, Xiaojun

2018-04-01

The structural, electronic, and magnetic properties of single-walled Mo2C nanotubes are investigated by using first-principles calculations. We establish that single-walled Mo2C nanotubes can be rolled up from a graphene-like Mo2C monolayer with H- or T-type phase, i.e. H-Mo2C and T-Mo2C nanotubes. The armchair-type T-Mo2C nanotubes are more energetically stable than H-Mo2C nanotubes with the same diameter, while zigzag-type H-Mo2C nanotubes are more energetically stable than T-Mo2C nanotubes. In particular, (8, 0) H-Mo2C nanotube are more stable than Mo2C monolayer due to structural deformation. All Mo2C nanotubes are magnetic metals, independent of their chirality, and the magnetic moments of Mo atoms in the outer layer are larger than the inner. The ionic and metallic bonds in Mo2C nanotubes and delocalized electrons around Mo atoms lead to the versatile electronic and magnetic properties in them, endowing them potential applications in catalysts and electronics.

Hydrogen spillover in Pt-single-walled carbon nanotube composites: formation of stable C-H bonds.

Science.gov (United States)

Bhowmick, Ranadeep; Rajasekaran, Srivats; Friebel, Daniel; Beasley, Cara; Jiao, Liying; Ogasawara, Hirohito; Dai, Hongjie; Clemens, Bruce; Nilsson, Anders

2011-04-13

Using in situ electrical conductivity and ex situ X-ray photoelectron spectroscopy (XPS) measurements, we have examined how the hydrogen uptake of single-walled carbon nanotubes (SWNTs) is influenced by the addition of Pt nanoparticles. The conductivity of platinum-sputtered single-walled carbon nanotubes (Pt-SWNTs) during molecular hydrogen exposure decreased more rapidly than that of the corresponding pure SWNTs, which supports a hydrogenation mechanism facilitated by "spillover" of dissociated hydrogen from the Pt nanoparticles. C 1s XPS spectra indicate that the Pt-SWNTs store hydrogen by means of chemisorption, that is, covalent C-H bond formation: molecular hydrogen charging at elevated pressure (8.27 bar) and room temperature yielded Pt-SWNTs with up to 16 ± 1.5 at. % sp(3)-hybridized carbon atoms, which corresponds to a hydrogen-storage capacity of 1.2 wt % (excluding the weight of Pt nanoparticles). Pt-SWNTs prepared by the Langmuir-Blodgett (LB) technique exhibited the highest Pt/SWNT ratio and also the best hydrogen uptake. © 2011 American Chemical Society

Hydrogen storage in single-wall carbon nano-tubes by means of laser excitation

International Nuclear Information System (INIS)

Oksengorn, B.

2010-01-01

A new mode for hydrogen adsorption and storage in single-wall carbon nano-tubes is used, on the basis of laser excitation. Remember that this method has been useful to obtain, in the case of the fullerene C 60 , many complex C 60 -atoms or C 60 -molecules, where atoms or molecular particles are trapped inside the C 60 -molecules. We think this method might be important to store many hydrogen molecules inside carbon nano-tubes. (author)

A new clamp method for firing bricks | Obeng | Journal of Applied ...

African Journals Online (AJOL)

A new clamp method for firing bricks. ... Journal of Applied Science and Technology ... To overcome this operational deficiencies, a new method of firing bricks that uses brick clamp technique that incorporates a clamp wall of 60 cm thickness, a six tier approach of sealing the top of the clamp (by combination of green bricks) ...

Energy transfer from natural photosynthetic complexes to single-wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Wiwatowski, Kamil [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Dużyńska, Anna; Świniarski, Michał [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Szalkowski, Marcin [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Zdrojek, Mariusz; Judek, Jarosław [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw (Poland); Mackowski, Sebastian, E-mail: mackowski@fizyka.umk.pl [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Wroclaw Research Center EIT+, Stablowicka 147, Wroclaw (Poland); Kaminska, Izabela [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland)

2016-02-15

Combination of fluorescence imaging and spectroscopy results indicates that single-walled carbon nanotubes are extremely efficient quenchers of fluorescence emission associated with chlorophylls embedded in a natural photosynthetic complex, peridinin-chlorophyll-protein. When deposited on a network of the carbon nanotubes forming a thin film, the emission of the photosynthetic complexes diminishes almost completely. This strong reduction of fluorescence intensity is accompanied with dramatic shortening of the fluorescence lifetime. Concluding, such thin films of carbon nanotubes can be extremely efficient energy acceptors in structures involving biologically functional complexes. - Highlights: • Fluorescence imaging of carbon nanotube - based hybrid structure. • Observation of efficient energy transfer from chlorophylls to carbon nanotubes.

Hardness of high-pressure high-temperature treated single-walled carbon nanotubes

International Nuclear Information System (INIS)

Kawasaki, S.; Nojima, Y.; Yokomae, T.; Okino, F.; Touhara, H.

2007-01-01

We have performed high-pressure high-temperature (HPHT) treatments of high quality single-walled carbon nanotubes (SWCNTs) over a wide pressure-temperature range up to 13 GPa-873 K and have investigated the hardness of the HPHT-treated SWCNTs using a nanoindentation technique. It was found that the hardness of the SWCNTs treated at pressures greater than 11 GPa and at temperatures higher than 773 K is about 10 times greater than that of the SWCNTs treated at low temperature. It was also found that the hardness change of the SWCNTs is related to the structural change by the HPHT treatments which was based on synchrotron X-ray diffraction measurements

Ion mass dependence for low energy channeling in single-wall nanotubes

International Nuclear Information System (INIS)

Zheng Liping; Zhu Zhiyuan; Li Yong; Zhu Dezhang; Xia Huihao

2008-01-01

An Monte Carlo (MC) simulation program has been used to study ion mass dependence for the low energy channeling of natural- and pseudo-Ar ions in single-wall nanotubes. The MC simulations show that the channeling critical angle Ψ C obeys the (E) -1/2 and the (M 1 ) -1/2 rules, where E is the incident energy and M 1 is the ion mass. The reason for this may be that the motion of the channeled (or de-channeled) ions should be correlated with both the incident energy E and the incident momentum (2M 1 E) 1/2 , in order to obey the conservation of energy and momentum

Atomic scale mass delivery driven by bend kink in single walled carbon nanotube

International Nuclear Information System (INIS)

Kan Biao; Ding Jianning; Ling Zhiyong; Yuan Ningyi; Cheng Guanggui

2010-01-01

The possibility of atomic scale mass delivery by bend kink in single walled carbon nanotube was investigated with the aid of molecular dynamics simulation. By keeping the bending angle while moving the tube end, the encapsulated atomic scale mass such as atom, molecule and atom group were successfully delivered through the nanotube. The van der Waals interaction between the encapsulated mass and the tube wall provided the driving force for the delivery. There were no dramatic changes in the van der Waals interaction, and a smooth and steady delivery was achieved when constant loading rate was applied. The influence of temperature on the atom group delivery was also analyzed. It is found raising temperature is harmful to the smooth movement of the atom group. However, the delivery rate can be promoted under higher temperature when the atom group is situated before the kink during the delivery.

Effect of hydrogen on the growth and morphology of single wall carbon nanotubes synthesized on a Fe-Mo/MgO catalytic system

Energy Technology Data Exchange (ETDEWEB)

Biris, Alexandru R. [National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca, RO-3400 (Romania)], E-mail: biris@oc1.itim-cj.ro; Li Zhongrui; Dervishi, Enkeleda [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Lupu, Dan [National Institute for Research and Development of Isotopic and Molecular Technologies, Cluj Napoca, RO-3400 (Romania); Xu Yang; Saini, Viney [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Watanabe, Fumiya [Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Biris, Alexandru S. [Applied Science Department, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States); Nanotechnology Center, University of Arkansas at Little Rock, 2801 S. University Ave, Little Rock, AR 72204 (United States)], E-mail: asbiris@ualr.edu

2008-04-21

Single wall carbon nanotubes were synthesized from thermal pyrolysis of methane on a Fe-Mo/MgO catalyst by radio frequency catalytic chemical vapor deposition (RF-CVD) using argon as a carrier gas. Controlled amounts of hydrogen (H{sub 2}/CH{sub 4}=0-1 v/v) were introduced in separate experiments along with the carbon source. The properties and morphology of the synthesized single wall carbon nanotubes were monitored by transmission electron microscopy, Raman scattering, and thermogravimetric analysis. The nanotubes with the highest crystallinity were obtained with H{sub 2}/CH{sub 4}=0.6. By monitoring the Radial Breathing Modes present in the Raman spectra of the single-wall carbon nanotube samples, the variation of the structural and morphological properties of the carbon nanotubes with the flow level of hydrogen, reflect changes of the catalyst systems induced by the presence of hydrogen.

Interaction between fullerene halves C_n (n ≤ 40) and single wall carbon nanotube

International Nuclear Information System (INIS)

Sharma, Amrish; Kaur, Sandeep; Mudahar, Isha

2016-01-01

We have investigated the structural and electronic properties of carbon nanotube with small fullerene halves C_n (n ≤ 40) which are covalently bonded to the side wall of an armchair single wall carbon nanotube (SWCNT) using first principle method based on density functional theory. The fullerene size results in weak bonding between fullerene halves and carbon nanotube (CNT). Further, it was found that the C-C bond distance that attaches the fullerene half and CNT is of the order of 1.60 Å. The calculated binding energies indicate the stability of the complexes formed. The HOMO-LUMO gaps and electron density of state plots points towards the metallicity of the complex formed. Our calculations on charge transfer reveal that very small amount of charge is transferred from CNT to fullerene halves.

A photovoltaic self-powered gas sensor based on a single-walled carbon nanotube/Si heterojunction.

Science.gov (United States)

Liu, L; Li, G H; Wang, Y; Wang, Y Y; Li, T; Zhang, T; Qin, S J

2017-12-07

We present a novel photovoltaic self-powered gas sensor based on a p-type single-walled carbon nanotube (SWNT) and n-type silicon (n-Si) heterojunction. The energy from visible light suffices to drive the device owing to a built-in electric field (BEF) induced by the differences between the Fermi levels of SWNTs and n-Si.

Selective detection of SO2 at room temperature based on organoplatinum functionalized single-walled carbon nanotube field effect transistors

NARCIS (Netherlands)

Cid, C.C.; Jimenez-Cadena, G.; Riu, J.; Maroto, A.; Rius, F.X.; Batema, G.D.; van Koten, G.

2009-01-01

We report a field effect transistor (FET) based on a network of single-walled carbon nanotubes (SWCNTs) that for the first time can selectively detect a single gaseous molecule in air by chemically functionalizing the SWCNTs with a selective molecular receptor. As a target model we used SO2. The

Printable Thin Film Supercapacitors Using Single-Walled Carbon Nanotubes

KAUST Repository

Kaempgen, Martti

2009-05-13

Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics. © 2009 American Chemical Society.

Solar conduction heat transfer in fired clay bricks

Energy Technology Data Exchange (ETDEWEB)

Custodio-Garcia, E.; Andres Zarate, Esteban; Cordova, Quintiliano A. [Universidad Juarez Autonoma de Tabasco, DACB, Cunduacan, Tabasco 86680 (Mexico); Sebastian, P.J.; Campos-Alvarez, J. [CIE-UNAM, 62580 Temixco, Mor 62580 (Mexico); Trevino-Palacios, Carlos G. [Instituto Nacional de Astrofisica, Optica y Electronica. A.P. 51 Y 216. Puebla 72000 (Mexico); De la O-Leon, Hugo [Universidad Juarez Autonoma de Tabasco, DAIS, Cunduacan Tab (Mexico)

2005-07-15

When somebody is interested in building a house in the year-round-hot and humid regions, faces with the decision of using modern construction block material or the traditional red fired clay brick material. We performed mechanical and thermal controlled measurements on walls made using both materials. We found that the ancient tradition of using fired clay bricks, for the weather conditions in central Tabasco, represents an excellent alternative in cost and energy savings for construction.

Photon antibunching in single-walled carbon nanotubes at telecommunication wavelengths and room temperature

Energy Technology Data Exchange (ETDEWEB)

Endo, Takumi, E-mail: endou@az.appi.keio.ac.jp; Ishi-Hayase, Junko; Maki, Hideyuki, E-mail: maki@appi.keio.ac.jp [Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522 (Japan)

2015-03-16

We investigated the photoluminescence of individual air-suspended single-walled carbon nanotubes (SWNTs) from 6 to 300 K. Time-resolved and antibunching measurements over the telecommunication wavelength range were performed using a superconducting single-photon detector. We detected moderate temperature independent antibunching behavior over the whole temperature range studied. To investigate the exciton dynamics, which is responsible for the antibunching behavior, we measured excitation-power and temperature dependence of the photoluminescence spectra and lifetime decay curves. These measurements suggested an exciton confinement effect that is likely caused by high-dielectric amorphous carbon surrounding the SWNTs. These results indicate that SWNTs are good candidates for light sources in quantum communication technologies operating in the telecommunication wavelength range and at room temperature.

Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

Energy Technology Data Exchange (ETDEWEB)

Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

2011-02-01

An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

International Nuclear Information System (INIS)

Salinas-Torres, David; Huerta, Francisco; Montilla, Francisco; Morallon, Emilia

2011-01-01

An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong π-π interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

47 CFR 15.509 - Technical requirements for ground penetrating radars and wall imaging systems.

Science.gov (United States)

2010-10-01

..., fire fighting, emergency rescue, scientific research, commercial mining, or construction. (1) Parties... radars and wall imaging systems. 15.509 Section 15.509 Telecommunication FEDERAL COMMUNICATIONS... ground penetrating radars and wall imaging systems. (a) The UWB bandwidth of an imaging system operating...

Developing Xenopus Embryos Recover by Compacting and Expelling Single-Wall Carbon Nanotubes

Science.gov (United States)

Holt, Brian D.; Shawky, Joseph H.; Dahl, Kris Noel; Davidson, Lance A.; Islam, Mohammad F.

2015-01-01

Single-wall carbon nanotubes are high aspect ratio nanomaterials that are being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties, and chemical inertness. Because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single-wall carbon nanotubes exposed to the widely studied model organism Xenopus laevis (African clawed frog). Microinjection of experimental substances into the Xenopus embryo is a standard technique for toxicology studies and cellular lineage tracing. Here we report the surprising finding that superficial (12.5 ± 7.5 μm below the membrane) microinjection of nanotubes dispersed with Pluronic F127 into one-to-two cell Xenopus embryos resulted in the formation and expulsion of compacted, nanotube-filled, punctate masses, at the blastula to mid-gastrula developmental stages, which we call “boluses”. Such expulsion of microinjected materials by Xenopus embryos has not been reported before and is dramatically different from the typical distribution of the materials throughout the progeny of the microinjected cells. Previous studies of microinjections of nanomaterials such as nanodiamonds, quantum dots or spherical nanoparticles report that nanomaterials often induce toxicity and remain localized within the embryos. In contrast, our results demonstrate an active recovery pathway for embryos after exposure to Pluronic F127-coated nanotubes, which we speculate is due to a combined effect of the membrane activity of the dispersing agent, Pluronic F127, and the large aspect ratio of nanotubes. PMID:26153061

Developing Xenopus embryos recover by compacting and expelling single wall carbon nanotubes.

Science.gov (United States)

Holt, Brian D; Shawky, Joseph H; Dahl, Kris Noel; Davidson, Lance A; Islam, Mohammad F

2016-04-01

Single wall carbon nanotubes are high aspect ratio nanomaterials being developed for use in materials, technological and biological applications due to their high mechanical stiffness, optical properties and chemical inertness. Because of their prevalence, it is inevitable that biological systems will be exposed to nanotubes, yet studies of the effects of nanotubes on developing embryos have been inconclusive and are lacking for single wall carbon nanotubes exposed to the widely studied model organism Xenopus laevis (African clawed frog). Microinjection of experimental substances into the Xenopus embryo is a standard technique for toxicology studies and cellular lineage tracing. Here we report the surprising finding that superficial (12.5 ± 7.5 µm below the membrane) microinjection of nanotubes dispersed with Pluronic F127 into one- to two-cell Xenopus embryos resulted in the formation and expulsion of compacted, nanotube-filled, punctate masses, at the blastula to mid-gastrula developmental stages, which we call "boluses." Such expulsion of microinjected materials by Xenopus embryos has not been reported before and is dramatically different from the typical distribution of the materials throughout the progeny of the microinjected cells. Previous studies of microinjections of nanomaterials such as nanodiamonds, quantum dots or spherical nanoparticles report that nanomaterials often induce toxicity and remain localized within the embryos. In contrast, our results demonstrate an active recovery pathway for embryos after exposure to Pluronic F127-coated nanotubes, which we speculate is due to a combined effect of the membrane activity of the dispersing agent, Pluronic F127, and the large aspect ratio of nanotubes. Copyright © 2015 John Wiley & Sons, Ltd.

Debundling of single-walled carbon nanotubes by using natural polyelectrolytes

International Nuclear Information System (INIS)

Liu Yangqiao; Gao Lian; Zheng Shan; Wang Yan; Sun Jing; Kajiura, Hisashi; Li Yongming; Noda, Kazuhiro

2007-01-01

Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so forth, are reported for the first time to solubilize single-walled carbon nanotubes (SWNTs) in water through a noncovalent interaction. A variety of methods, including transmission electron microscopy (TEM), visible-near-infrared (vis-NIR) spectra, Raman spectra and zeta potential measurements, were used to characterize the NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated into thin bundles or individual tubes, even at NP concentrations as low as 0.15 mg ml -1 . Their high performance is attributed to the abundance of aromatic groups and ionized groups in the NP molecules. This method of solubilization opens the way for exploiting new natural materials as SWNT solubilizers and may find applications in nanocomposites, self-assembly, and so forth

Debundling of single-walled carbon nanotubes by using natural polyelectrolytes

Energy Technology Data Exchange (ETDEWEB)

Liu Yangqiao [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Gao Lian [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zheng Shan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wang Yan [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Sun Jing [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Kajiura, Hisashi [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan); Li Yongming [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan); Noda, Kazuhiro [Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan)

2007-09-12

Natural polyelectrolytes (NPs), including sodium lignosulfonate, humic acid and so forth, are reported for the first time to solubilize single-walled carbon nanotubes (SWNTs) in water through a noncovalent interaction. A variety of methods, including transmission electron microscopy (TEM), visible-near-infrared (vis-NIR) spectra, Raman spectra and zeta potential measurements, were used to characterize the NP-dispersed SWNT solutions. It is found that the SWNTs can be exfoliated into thin bundles or individual tubes, even at NP concentrations as low as 0.15 mg ml{sup -1}. Their high performance is attributed to the abundance of aromatic groups and ionized groups in the NP molecules. This method of solubilization opens the way for exploiting new natural materials as SWNT solubilizers and may find applications in nanocomposites, self-assembly, and so forth.

Literature study regarding fire protection in nuclear power plants. Part I: Fire rated separations

International Nuclear Information System (INIS)

Isaksson, S.

1995-06-01

This literature study has been made on behalf of the Swedish Nuclear Power Inspectorate. The aim is to describe different aspects of fire protection in nuclear power plants. Conventional building codes can not give guidance on where to make fire rated separations in order to separate redundant trains of safety systems. The separation must originate in functional demands from the authorities on what functions are essential during and after a fire, and under what circumstances these functions shall be retained, i.e. the number of independent faults and initiating events. As a basic demand it is suggested to rate the strength of separations according to conventional building code, based on fire load. The whole separating construction shall have the same fire rating, including the ventilation system. Deviations from the basic demand can de done in case it can be proven that it is possible to compensate some or all of the fire rating with other measures. There is a general lack of statistical information regarding the reliability of fire separating constructions such as walls, fire doors, penetration seals and fire dampers. The amount of cables penetrating a seal is in many cases much higher in real installations than what has been tested for type approval. It would therefore be valuable to perform a furnace test with a more representative amount of cables passing through a penetration seal. Tests have shown that the 20 foot horizontal separation distance stipulated by NRC is not a guarantee against fire damage. Spatial separations based on general requirements shall not be allowed, but considered from case to case based on actual circumstances. For fire protection by isolation or coatings, it is of great importance to choose the method of protection carefully, to be compatible with the material it shall be applied on, and the environment and types of fire that may occur. 48 refs, 2 figs, 5 tabs

Curvature dependence of single-walled carbon nanotubes for SO2 adsorption and oxidation

Science.gov (United States)

Chen, Yanqiu; Yin, Shi; Li, Yueli; Cen, Wanglai; Li, Jianjun; Yin, Huaqiang

2017-05-01

Porous carbon-based catalysts showing high catalytic activity for SO2 oxidation to SO3 is often used in flue gas desulfurization. Their catalytic activity has been ascribed in many publications to the microporous structure and the effect of its spatial confinement. First principles method was used to investigate the adsorption and oxidation of SO2 on the inner and outer surface of single-walled carbon nanotubes (SWCNTs) with different diameters. It is interesting to found that there is a direct correlation: the barrier for the oxidation O_SWCNT + SO2 → SO3 + SWCNT monotonically decreases with the increase of SWCNTs' curvature. The oxygen functional located at the inner wall of SWCNTs with small radius is of higher activity for SO2 oxidation, which is extra enhanced by the spatial confinement effects of SWCNTs. These findings can be useful for the development of carbon-based catalysts and provide clues for the optimization and design of porous carbon catalysts.

Fabrication and electrochemical properties of free-standing single-walled carbon nanotube film electrodes

International Nuclear Information System (INIS)

Niu Zhi-Qiang; Ma Wen-Jun; Dong Hai-Bo; Li Jin-Zhu; Zhou Wei-Ya

2011-01-01

An easily manipulative approach was presented to fabricate electrodes using free-standing single-walled carbon nanotube (SWCNT) films grown directly by chemical vapor deposition. Electrochemical properties of the electrodes were investigated. In comparison with the post-deposited SWCNT papers, the directly grown SWCNT film electrodes manifested enhanced electrochemical properties and sensitivity of sensors as well as excellent electrocatalytic activities. A transition from macroelectrode to nanoelectrode behaviours was observed with the increase of scan rate. The heat treatment of the SWCNT film electrodes increased the current signals of electrochemical analyser and background current, because the heat-treatment of the SWCNTs in air could create more oxide defects on the walls of the SWCNTs and make the surfaces of SWCNTs more hydrophilic. The excellent electrochemical properties of the directly grown and heat-treated free-standing SWCNT film electrodes show the potentials in biological and electrocatalytic applications. (cross-disciplinary physics and related areas of science and technology)

Functionalization of single-walled carbon nanotubes regulates their effect on hemostasis

International Nuclear Information System (INIS)

Sokolov, A V; Aseychev, A V; Kostevich, V A; Gusev, A A; Gusev, S A; Vlasova, I I

2011-01-01

Applications of single-walled carbon nanotubes (SWNTs) in medical field imply the use of drug-coupled carbon nanotubes as well as carbon nanotubes functionalized with different chemical groups that change nanotube surface properties and interactions between nanotubes and cells. Covalent attachment of polyethylene glycol (PEG) to carboxylated single-walled carbon nanotubes (c-SWNT) is known to prevent the nanotubes from interaction with macrophages. Here we characterized nanotube's ability to stimulate coagulation processes in platelet-poor plasma (PPP), and evaluated the effect of SWNTs on platelet aggregation in platelet-rich plasma (PRP). Our study showed that PEG-SWNT did not affect the rate of clotting in PPP, while c-SWNT shortened the clot formation time five times compared to the control PPP. Since c-SWNT failed to accelerate coagulation in plasma lacking coagulation factor XI, it may be suggested that c-SWNT affects the contact activation pathway. In PRP, platelets responded to both SWNT types with irreversible aggregation, as evidenced by changes in the aggregate mean radius. However, the rate of aggregation induced by c-SWNT was two times higher than it was with PEG-SWNT. Cytological analysis also showed that c-SWNT was two times more efficient when compared to PEG-SWNT in aggregating platelets in PRP. Taken together, our results show that functionalization of nanoparticles can diminish their negative influence on blood cells. As seen from our data, modification of c-SWNT with PEG, when only a one percent of carbon atoms is bound to polymer (70 wt %), decreased the nanotube-induced coagulation in PRP and repelled the accelerating effect on the coagulation in PPP. Thus, when functionalized SWNTs are used for administration into bloodstream of laboratory animals, their possible pro-coagulant and pro-aggregating properties must be taken into account.

Functionalization of single-walled carbon nanotubes regulates their effect on hemostasis

Energy Technology Data Exchange (ETDEWEB)

Sokolov, A V; Aseychev, A V; Kostevich, V A; Gusev, A A; Gusev, S A; Vlasova, I I, E-mail: irina.vlasova@yahoo.com [Research Institute for Physico-Chemical Medicine, FMBA, M. Pirogovskaya Str. 1a, Moscow (Russian Federation)

2011-04-01

Applications of single-walled carbon nanotubes (SWNTs) in medical field imply the use of drug-coupled carbon nanotubes as well as carbon nanotubes functionalized with different chemical groups that change nanotube surface properties and interactions between nanotubes and cells. Covalent attachment of polyethylene glycol (PEG) to carboxylated single-walled carbon nanotubes (c-SWNT) is known to prevent the nanotubes from interaction with macrophages. Here we characterized nanotube's ability to stimulate coagulation processes in platelet-poor plasma (PPP), and evaluated the effect of SWNTs on platelet aggregation in platelet-rich plasma (PRP). Our study showed that PEG-SWNT did not affect the rate of clotting in PPP, while c-SWNT shortened the clot formation time five times compared to the control PPP. Since c-SWNT failed to accelerate coagulation in plasma lacking coagulation factor XI, it may be suggested that c-SWNT affects the contact activation pathway. In PRP, platelets responded to both SWNT types with irreversible aggregation, as evidenced by changes in the aggregate mean radius. However, the rate of aggregation induced by c-SWNT was two times higher than it was with PEG-SWNT. Cytological analysis also showed that c-SWNT was two times more efficient when compared to PEG-SWNT in aggregating platelets in PRP. Taken together, our results show that functionalization of nanoparticles can diminish their negative influence on blood cells. As seen from our data, modification of c-SWNT with PEG, when only a one percent of carbon atoms is bound to polymer (70 wt %), decreased the nanotube-induced coagulation in PRP and repelled the accelerating effect on the coagulation in PPP. Thus, when functionalized SWNTs are used for administration into bloodstream of laboratory animals, their possible pro-coagulant and pro-aggregating properties must be taken into account.

Mapping the Daily Progression of Large Wildland Fires Using MODIS Active Fire Data

Science.gov (United States)

Veraverbeke, Sander; Sedano, Fernando; Hook, Simon J.; Randerson, James T.; Jin, Yufang; Rogers, Brendan

2013-01-01

High temporal resolution information on burned area is a prerequisite for incorporating bottom-up estimates of wildland fire emissions in regional air transport models and for improving models of fire behavior. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) active fire product (MO(Y)D14) as input to a kriging interpolation to derive continuous maps of the evolution of nine large wildland fires. For each fire, local input parameters for the kriging model were defined using variogram analysis. The accuracy of the kriging model was assessed using high resolution daily fire perimeter data available from the U.S. Forest Service. We also assessed the temporal reporting accuracy of the MODIS burned area products (MCD45A1 and MCD64A1). Averaged over the nine fires, the kriging method correctly mapped 73% of the pixels within the accuracy of a single day, compared to 33% for MCD45A1 and 53% for MCD64A1.

Mitsubishi latest coal fired USC boiler technology (CFE Pacifico 700 MW)

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, T.; Sakamoto, K. [Mitsubishi Heavy Industries, Ltd., Nagasaki (Japan). Power Systems; Fujitab, M. [Mitsubishi Heavy Industries, Ltd., Yokohama (Japan). Power Systems

2013-07-01

Mitsubishi Heavy Industries, Ltd. (MHI) has successfully completed commissioning work for CFE (Comision Federal de Electricidad) Pacifico 700 MW coal-fired unit in March 2010 which is the first supercritical unit in Latin America. This supercritical boiler was designed with state of the art technologies such as low NOx burners, high fineness pulverizers, advanced vertical furnace wall technology and so on. Especially the advanced vertical furnace wall technology with some improvements is a key technology to realize swift load changes such as 5% load per minute ramping rate with assuring dynamic characteristics. Recently the requirement of the high efficiency and the swift load changes for the power boilers has been increased so that even a coal-fired unit needs flexible operation characteristics for balancing variety of power sources. One of the challenges for the swift load change is to keep the furnace wall metal temperature low during the load change, which the advanced vertical furnace wall could realize. The report describes the features of the unit and commissioning result including load swing test results in details.

Application of electron energy loss spectroscopy for single wall carbon nanotubes (review)

International Nuclear Information System (INIS)

Mittal, N.; Jain, S.; Mittal, J.

2015-01-01

Electron energy loss spectroscopy (EELS) is among the few techniques that are available for the characterization of modified single wall carbon nanotubes (SWCNTs) having nanometer dimensions (~1-3 nm). CNTs can be modified either by surface functionalization or coating, between bundles of nanotubes by doping, intercalation and fully or partially filling the central core. EELS is an exclusive technique for the identification, composition analysis, and crystallization studies of the chemicals and materials used for the modification of SWCNTs. The present paper serves as a compendium of research work on the application of EELS for the characterization of modified SWCNTs. (authors)

Improving the conductivity of single-walled carbon nanotubes films by heat treatment

Energy Technology Data Exchange (ETDEWEB)

Wang Jiaping [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Superfine Microstructures, 1295 Dingxi Road, Shanghai 200050 (China); Sun Jing, E-mail: jingsun@mail.sic.ac.c [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Superfine Microstructures, 1295 Dingxi Road, Shanghai 200050 (China); Gao Lian, E-mail: liangaoc@online.sh.c [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Superfine Microstructures, 1295 Dingxi Road, Shanghai 200050 (China); Liu Yangqiao; Wang Yan; Zhang Jing [State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Superfine Microstructures, 1295 Dingxi Road, Shanghai 200050 (China); Kajiura, Hisashi; Li Yongming; Noda, Kazuhiro [Advanced Materials Laboratories, Sony Corporation, Atsugi Tec. No. 2, 4-16-1 Okata Atsugi, Kanagawa 243-0021 (Japan)

2009-10-19

A simple heat treatment method was applied to remove surfactants remaining in the single-walled carbon nanotubes (SWNTs) films at 300 deg. C for 5 h in air. Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and reflected light interference microscope (RLIM) were employed to verify the elimination of surfactants. The comprehensive performance, especially the conductivity, could be improved by more than one order after heat treatment. For example, using SDBS as dispersant, the sheet resistance decreased from 782,600 OMEGA/square to 40,460 OMEGA/square with the transmittance of about 99.5% at 550 nm.

Transient reflectivity on vertically aligned single-wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Galimberti, Gianluca; Ponzoni, Stefano; Ferrini, Gabriele [Interdisciplinary Laboratory for Advanced Materials Physics (i-LAMP) and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia (Italy); Hofmann, Stephan [Department of Engineering, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Arshad, Muhammad [Zernike Institute for Advanced Materials, University of Groningen (Netherlands); ICTP, Strada Costiera 11, I-34151 Trieste (Italy); National Centre for Physics Quaid-i-Azam University Islamabad (Pakistan); Cepek, Cinzia [Istituto Officina dei Materiali — CNR, Laboratorio TASC, Area Science Park, Basovizza, I-34149 Trieste (Italy); Pagliara, Stefania, E-mail: pagliara@dmf.unicatt.it [Interdisciplinary Laboratory for Advanced Materials Physics (i-LAMP) and Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, I-25121 Brescia (Italy)

2013-09-30

One-color transient reflectivity measurements are carried out on two different samples of vertically aligned single-wall carbon nanotube bundles and compared with the response recently published on unaligned bundles. The negative sign of the optical response for both samples indicates that the free electron character revealed on unaligned bundles is only due to the intertube interactions favored by the tube bending. Neither the presence of bundles nor the existence of structural defects in aligned bundles is able to induce a free-electron like behavior of the photoexcited carriers. This result is also confirmed by the presence of non-linear excitonic effects in the transient response of the aligned bundles. - Highlights: • Transient reflectivity measurements on two aligned carbon nanotube samples • Relationship between unalignment and/or bundling and intertube interaction • The bundling is not able to modify the intertube interactions • The presence of structural defects does not affect the intertube interactions • A localized exciton-like behavior has been revealed in these samples.

A Single-Walled Carbon Nanotube Network Gas Sensing Device

Directory of Open Access Journals (Sweden)

I-Ju Teng

2011-08-01

Full Text Available The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT networks. The SWCNT networks are synthesized on Al2O3-deposted SiO2/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD. The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO2 and NH3 vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO2 and 24 ppm for NH3.

Single-wall carbon nanotube chemical attachment at platinum electrodes

International Nuclear Information System (INIS)

Rosario-Castro, Belinda I.; Contes-de-Jesus, Enid J.; Lebron-Colon, Marisabel; Meador, Michael A.; Scibioh, M. Aulice; Cabrera, Carlos R.

2010-01-01

Self-assembled monolayer (SAM) techniques were used to adsorb 4-aminothiophenol (4-ATP) on platinum electrodes in order to obtain an amino-terminated SAM as the base for the chemical attachment of single-wall carbon nanotubes (SWCNTs). A physico-chemical, morphological and electrochemical characterizations of SWCNTs attached onto the modified Pt electrodes was done by using reflection-absorption infrared spectroscopy (RAIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and cyclic voltammetry (CV) techniques. The SWNTs/4-ATP/Pt surface had regions of small, medium, and large thickness of carbon nanotubes with heights of 100-200 nm, 700 nm to 1.5 μm, and 1.0-3.0 μm, respectively. Cyclic voltammetries (CVs) in sulfuric acid demonstrated that attachment of SWNTs on 4-ATP/Pt is markedly stable, even after 30 potential cycles. CV in ruthenium hexamine was similar to bare Pt electrodes, suggesting that SWNTs assembly is similar to a closely packed microelectrode array.

The reaction of lithium metal vapor with single walled carbon nanotubes of large diameters

Czech Academy of Sciences Publication Activity Database

Kalbáč, Martin; Kavan, Ladislav; Dunsch, L.

2009-01-01

Roč. 246, 11-12 (2009), s. 2428-2431 ISSN 0370-1972 R&D Projects: GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA AV ČR IAA400400804; GA ČR GC203/07/J067; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : lithium * single walled carbon nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 1.150, year: 2009

Growth of single-wall carbon nanotubes by chemical vapor deposition for electrical devices

OpenAIRE

Furer, Jürg

2006-01-01

Carbon emerges in di®erent forms. Diamond and graphite have been well known mate- rials for centuries. Moreover fullerenes and nanotubes were discovered only a few years ago. H. W. Kroto et al. depicted the fullerenes in 1985 [1]. A few years later, in 1991, S. Iijima described carbon nanotubes (CNTs) for the ¯rst time [2] (Figure 1.1). CNTs have a close relation to graphite, since a single-wall carbon nanotube is like a rolled-up graphite mono layer. However a nanotube has wi...

The effect of topological defects and oxygen adsorption on the electronic transport properties of single-walled carbon-nanotubes

International Nuclear Information System (INIS)

Grujicic, M.; Cao, G.; Singh, R.

2003-01-01

Ab initio density functional theory (DFT) calculations of the interactions between isolated infinitely-long semiconducting zig-zag (10, 0) or isolated infinitely-long metallic arm-chair (5, 5) single-walled carbon-nanotubes (SWCNTs) and single oxygen-molecules are carried out in order to determine the character of molecular-oxygen adsorption and its effect on electronic transport properties of these SWCNTs. A Green's function method combined with a nearest-neighbor tight-binding Hamiltonian in a non-orthogonal basis is used to compute the electrical conductance of SWCNTs and its dependence on the presence of topological defects in SWCNTs and of molecular-oxygen adsorbates. The computational results obtained show that in both semiconducting and metallic SWCNTs, oxygen-molecules are physisorbed to the defect-free nanotube walls, but when such walls contain topological defects, oxygen-molecules become strongly chemisorbed. In semiconducting (10, 0) SWCNTs, physisorbed O 2 -molecules are found to significantly increase electrical conductance while the effect of 7-5-5-7 defects is practically annulled by chemisorbed O 2 -molecules. In metallic (5, 5) SWCNTs, both O 2 adsorbates and 7-5-5-7 defects are found to have a relatively small effect on electrical conductance of these nanotubes

46 CFR 132.130 - Fire stations.

Science.gov (United States)

2010-10-01

... a single length of hose. (b) Each part of the main machinery space, including the shaft alley if it... to protect its hose from heavy weather. (n) Each section of fire hose must be lined commercial fire...

Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

Energy Technology Data Exchange (ETDEWEB)

Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W., E-mail: leesw@konkuk.ac.kr [Division of Quantum Phases and Devices, School of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Na, J.; Kim, G. T. [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, B. J.; Kim, J. J.; Jeong, G. H. [Department of Nano Applied Engineering, Kangwon National University, Kangwon-do 200-701 (Korea, Republic of); Lee, I.; Kim, K. S. [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of)

2015-07-20

A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

Interaction of amidated single-walled carbon nanotubes with protein by multiple spectroscopic methods

Energy Technology Data Exchange (ETDEWEB)

Li, Lili [China Pharmaceutical University, Nanjing 210009 (China); The Nursing College of Pingdingshan University, Pingdingshan 467000 (China); Lin, Rui [Yancheng Health Vocational and Technical College, Yancheng 224005 (China); He, Hua, E-mail: dochehua@163.com [China Pharmaceutical University, Nanjing 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, China Pharmaceutical University, Nanjing 210009 (China); Sun, Meiling, E-mail: sml-nir@sohu.com [China Pharmaceutical University, Nanjing 210009 (China); Jiang, Li; Gao, Mengmeng [China Pharmaceutical University, Nanjing 210009 (China)

2014-01-15

The aim of this work was to investigate the detailed interaction between BSA and amidated single walled carbon nanotubes (e-SWNTs) in vitro. Ethylenediamine (EDA) was successfully linked on the surface of single-walled carbon nanotubes (SWNTs) via acylation to improve their dispersion and to introduce active groups. Bovine serum albumin (BSA) was selected as the template protein to inspect the interaction of e-SWNTs with protein. Decreases in fluorescence intensity of BSA induced by e-SWNTs demonstrated the occurrence of interaction between BSA and e-SWNTs. Quenching parameters and different absorption spectra for e-SWNTs–BSA show that the quenching effect of e-SWNTs was static quenching. Hydrophobic force had a leading contribution to the binding roles of BSA on e-SWNTs, which was confirmed by positive enthalpy change and entropy change. The interference of Na{sup +} with the quenching effect of e-SWNTs authenticated that electrostatic force existed in the interactive process simultaneously. The hydrophobicity of amino acid residues markedly increased with the addition of e-SWNTs viewed from UV spectra of BSA. The content of α-helix structure in BSA decreased by 6.8% due to the addition of e-SWNTs, indicating that e-SWNTs have an effect on the secondary conformation of BSA. -- Highlights: • The interaction between e-SWNTs and BSA was investigated by multiple spectroscopic methods. • Quenching mechanism was static quenching. • Changes in structure of BSA were inspected by synchronous fluorescence, UV–vis and CD spectrum.

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

Directory of Open Access Journals (Sweden)

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

2008-01-01

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

Bayesian nonparametric modeling for comparison of single-neuron firing intensities.

Science.gov (United States)

Kottas, Athanasios; Behseta, Sam

2010-03-01

We propose a fully inferential model-based approach to the problem of comparing the firing patterns of a neuron recorded under two distinct experimental conditions. The methodology is based on nonhomogeneous Poisson process models for the firing times of each condition with flexible nonparametric mixture prior models for the corresponding intensity functions. We demonstrate posterior inferences from a global analysis, which may be used to compare the two conditions over the entire experimental time window, as well as from a pointwise analysis at selected time points to detect local deviations of firing patterns from one condition to another. We apply our method on two neurons recorded from the primary motor cortex area of a monkey's brain while performing a sequence of reaching tasks.

Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests.

Science.gov (United States)

Fry, Danny L; Stephens, Scott L; Collins, Brandon M; North, Malcolm P; Franco-Vizcaíno, Ernesto; Gill, Samantha J

2014-01-01

In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha(-1), and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥ 56%) in large patches (≥ 10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

Purity Evaluation of Single-Walled Carbon Nanotubes Using Thermogravimetric Analysis

International Nuclear Information System (INIS)

Goak, Jeung Choon; Kim, Tae Yang; Jung, Jongwan; Seo, Young-Soo; Lee, Naesung; Sok, Junghyun

2013-01-01

This study evaluated the purity of single-walled carbon nanotubes (SWCNTs) in the arc-synthesized SWCNT samples by using thermogravimetric analysis (TGA). The as-produced SWCNT samples were heat-treated in air for 20 h at 275-475°C and characterized by scanning and transmission electron microscopes and TGA to establish oxidation temperature ranges of SWCNTs and carbonaceous impurities comprising the samples. Based on these oxidation temperature ranges, derivative thermogravimetric curves were deconvoluted, and differentiated peaks were assigned to SWCNTs and carbonaceous impurities. The compositions and the SWCNT purities of the samples were obtained simply by calculating the areal ratios under the deconvoluted curves. TGA studies on purity evaluation and thermal stabilities of SWCNTs and carbonaceous impurities are likely to provide us with a simple route of thermal oxidation purification to acquire high-purity SWCNT samples.

Structural and electronic properties of chiral single-wall copper nanotubes

Science.gov (United States)

Duan, YingNi; Zhang, JianMin; Xu, KeWei

2014-04-01

The structural, energetic and electronic properties of chiral ( n, m) (3⩽ n⩽6, n/2⩽ m⩽ n) single-wall copper nanotubes (CuNTs) have been investigated by using projector-augmented wave method based on density-functional theory. The (4, 3) CuNT is energetically stable and should be observed experimentally in both free-standing and tip-suspended conditions, whereas the (5, 5) and (6, 4) CuNTs should be observed in free-standing and tip-suspended conditions, respectively. The number of conductance channels in the CuNTs does not always correspond to the number of atomic strands comprising the nanotube. Charge density contours show that there is an enhanced interatomic interaction in CuNTs compared with Cu bulk. Current transporting states display different periods and chirality, the combined effects of which lead to weaker chiral currents on CuNTs.

Revealing properties of single-walled carbon nanotubes under high pressure

CERN Document Server

Tang Jie; Sasaki, T; Yudasaka, M; Matsushita, A; Iijima, S

2002-01-01

It was found by the x-ray diffraction experiment under hydrostatic pressure that the carbon nanotubes are compressed easily with a high volume compressibility of 0.024 GPa sup - sup 1. The single-walled carbon nanotubes are polygonized when they form bundles of hexagonal close-packed structure and the inter-tubular gap is smaller than the equilibrium spacing of graphite. Under high pressure, further polygonization occurs to accommodate the extra amount of volume reduction. The ratio of the short and the long diagonals in the hexagonalized cross section is found to have changed from 0.991 at zero pressure to 0.982 at 1.5 GPa pressure, when the Bragg reflection from the nanotube lattice diminished. Accompanying polygonization, a discontinuous change in electrical resistivity was observed at 1.5 GPa pressure, suggesting a phase transition had occurred.

Firing patterns in the adaptive exponential integrate-and-fire model.

Science.gov (United States)

Naud, Richard; Marcille, Nicolas; Clopath, Claudia; Gerstner, Wulfram

2008-11-01

For simulations of large spiking neuron networks, an accurate, simple and versatile single-neuron modeling framework is required. Here we explore the versatility of a simple two-equation model: the adaptive exponential integrate-and-fire neuron. We show that this model generates multiple firing patterns depending on the choice of parameter values, and present a phase diagram describing the transition from one firing type to another. We give an analytical criterion to distinguish between continuous adaption, initial bursting, regular bursting and two types of tonic spiking. Also, we report that the deterministic model is capable of producing irregular spiking when stimulated with constant current, indicating low-dimensional chaos. Lastly, the simple model is fitted to real experiments of cortical neurons under step current stimulation. The results provide support for the suitability of simple models such as the adaptive exponential integrate-and-fire neuron for large network simulations.

Ab initio study of F- and Cl-functionalized single wall carbon nanotubes

International Nuclear Information System (INIS)

Pan, H; Feng, Y P; Lin, J Y

2006-01-01

First-principles calculations were carried out to study the functionalization of single wall carbon nanotubes by the chemical absorption of F and Cl atoms. Our results confirmed that the band gap of semiconductor zigzag carbon nanotubes is reduced on addition of F or Cl atoms on the walls of the nanotubes. For metallic armchair nanotubes, the doubly degenerate states crossing the Fermi level were separated by the introduction of F or Cl atoms. An additional energy level emerged near the Fermi level, due to coupling between the carbon nanotube and the F or Cl atom. For zigzag nanotubes, charge transfers of 0.27e from the tube to the Cl atom and of 0.41e to the F atom took place, while for armchair nanotubes, the charge transfers from the nanotube to Cl and F are 0.25 and 0.42e, respectively. The Cl-C and F-C bond lengths were found to be 2.09 and 1.49 A, respectively. The systems show semiconducting behaviour when charged with one electron per halogen atom, but remain metallic under hole injection, regardless of the chirality of the carbon nanotubes

High-resolution 13C nuclear magnetic resonance evidence of phase transition of Rb,Cs-intercalated single-walled nanotubes

KAUST Repository

Bouhrara, M.; Saih, Y.; Wågberg, T.; Goze-Bac, C.; Abou-Hamad, E.

2011-01-01

charge transfer is applicable at low intercalation level. The new phase at high intercalation level is accompanied by a hybridization of alkali (s) orbitals with the carbon (sp2) orbitals of the single walled nanotubes, which indicate bundle surface sites

Interactions of phospholipid monolayer with single-walled carbon nanotube wrapped by lysophospholipid

Energy Technology Data Exchange (ETDEWEB)

Lim, Siwool; Kim, Hyungsu, E-mail: hkim@dku.edu

2012-10-01

In this study, we prepared single-walled carbon nanotubes (SWNTs) wrapped by 1-stearoyl-2-hydroxy-sn-glycero-3-phospho-(1 Prime -rac-glycerol) (LPG), leading to a complex of SWNT-LPG. In an attempt to investigate the interactions of SWNT-LPG with a mimicked cell surface, SWNT-LPG solution was injected into the sub-phase of Langmuir trough to form a mixed monolayer with dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG), respectively. In addition to the measurement of typical surface pressure-area isotherms under compression mode, area changes occurring during insertion of SWNT-LPG into the monolayer were recorded at various surface pressures. Changes in surface potential were also measured for evident tracing of the degree of interactions between sub-phase and monolayer. A systematic comparison of relaxation patterns and insertion behavior along with surface potential data provided a rational basis to distinguish the degree of interactions between SWNT-LPG and the designated monolayer. The observed tendencies were found to be in accordance with the surface topography as revealed by the tapping mode atomic force microscopy. It was consistently observed that SWNT-LPG interacted with DPPC to a greater extent than with DPPG, when the sufficient coverage of nanotube surface by LPG molecules was assured. - Highlights: Black-Right-Pointing-Pointer Complex of single-walled carbon nanotubes and lysophospholipid (SWNT-LPG) is formed. Black-Right-Pointing-Pointer Composite monolayer is formed by inserting SWNT-LPG into the phospholipid monolayer. Black-Right-Pointing-Pointer We measure area-pressure responses and dipole potentials during the insertion process. Black-Right-Pointing-Pointer Properties of composite monolayer depend on the kind of phospholipid and LPG content.

Interaction between fullerene halves C{sub n} (n ≤ 40) and single wall carbon nanotube

Energy Technology Data Exchange (ETDEWEB)

Sharma, Amrish, E-mail: amrish99@gmail.com; Kaur, Sandeep, E-mail: sipusukhn@gmail.com [Department of Physics, Punjabi University, Patiala (India); Mudahar, Isha, E-mail: isha@pbi.ac.in [Department of Basic and Applied Sciences, Punjabi University, Patiala (India)

2016-05-06

We have investigated the structural and electronic properties of carbon nanotube with small fullerene halves C{sub n} (n ≤ 40) which are covalently bonded to the side wall of an armchair single wall carbon nanotube (SWCNT) using first principle method based on density functional theory. The fullerene size results in weak bonding between fullerene halves and carbon nanotube (CNT). Further, it was found that the C-C bond distance that attaches the fullerene half and CNT is of the order of 1.60 Å. The calculated binding energies indicate the stability of the complexes formed. The HOMO-LUMO gaps and electron density of state plots points towards the metallicity of the complex formed. Our calculations on charge transfer reveal that very small amount of charge is transferred from CNT to fullerene halves.

Microchip electrophoresis-single wall carbon nanotube press-transferred electrodes for fast and reliable electrochemical sensing of melatonin and its precursors.

Science.gov (United States)

Gomez, Federico José Vicente; Martín, Aída; Silva, María Fernanda; Escarpa, Alberto

2015-08-01

In the current work, single-wall carbon nanotube press-transferred electrodes (SW-PTEs) were used for detection of melatonin (MT) and its precursors tryptophan (Trp) and serotonin (5-HT) on microchip electrophoresis (ME). SW-PTEs were simply fabricated by press transferring a filtered dispersion of single-wall carbon nanotubes on a nonconductive PMMA substrate, where single-wall carbon nanotubes act as exclusive transducers. The coupling of ME-SW-PTEs allowed the fast detection of MT, Trp, and 5-HT in less than 150 s with excellent analytical features. It exhibited an impressive antifouling performance with RSD values of ≤2 and ≤4% for migration times and peak heights, respectively (n = 12). In addition, sample analysis was also investigated by analysis of 5-HT, MT, and Trp in commercial samples obtaining excellent quantitative and reproducible recoveries with values of 96.2 ± 1.8%, 101.3 ± 0.2%, and 95.6 ± 1.2% for 5-HT, MT, and Trp, respectively. The current novel application reveals the analytical power of the press-transfer technology where the fast and reliable determination of MT and its precursors were performed directly on the nanoscale carbon nanotube detectors without the help of any other electrochemical transducer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of the interaction of carbon dioxide fluid with internal and external single-wall carbon nanotubes by DFT

Directory of Open Access Journals (Sweden)

M. Oftadeh

2011-07-01

Full Text Available The effective parameters of (5, 0 and (5, 5 single-wall carbon nanotubes during the interaction with carbon dioxide as sensors are determined. The interaction of carbon dioxide  molecules with internal and external walls of the nanotubes is studied using Gaussian 03 coding by density functional theory (DFT at the B3LYP/6-311G level of theory. CO2 rotation around tube axles vertically and parallel to the internal and external walls has been investigated. The carbon dioxide molecule is predicted to bind only weakly to nanotubes, and the tube-molecule interactions can be identified as physisorption. CO2 adsorption is stronger on external wallsthan on internal walls, and adsorption on the external wall of (5, 0 is stronger than on the external wall of (5, 5; the adsorption energies are exothermic and equal to -0.8884 and -0.0528 kcal/mol, respectively. The rotation energy barrier for (5, 5 is lower than that for (5, 0 in all rotations, therefore in these interactions (5, 5 is more active. The energy gap significantly changes in the presence of  carbon  dioxide molecules on the inside surface of (5, 0 and the electric conductivity is affected, but no remarkable change is observed in the electronic structure of (5, 5.

Diameter Tuning of Single-Walled Carbon Nanotubes by Diffusion Plasma CVD

Directory of Open Access Journals (Sweden)

Toshiaki Kato

2011-01-01

Full Text Available We have realized a diameter tuning of single-walled carbon nanotubes (SWNTs by adjusting process gas pressures with plasma chemical vapor deposition (CVD. Detailed photoluminescence measurements reveal that the diameter distribution of SWNTs clearly shifts to a large-diameter region with an increase in the pressure during plasma CVD, which is also confirmed by Raman scattering spectroscopy. Based on the systematical investigation, it is found that the main diameter of SWNTs is determined by the pressure during the heating in an atmosphere of hydrogen and the diameter distribution is narrowed by adjusting the pressure during the plasma generation. Our results could contribute to an application of SWNTs to high-performance thin-film transistors, which requires the diameter-controlled semiconductor-rich SWNTs.

Design and Fabrication of Single-Walled Carbon Nanonet Flexible Strain Sensors

Directory of Open Access Journals (Sweden)

Trung Kien Vu

2012-03-01

Full Text Available This study presents a novel flexible strain sensor for real-time strain sensing. The material for strain sensing is single-walled carbon nanonets, grown using the alcohol catalytic chemical vapor deposition method, that were encapsulated between two layers of Parylene-C, with a polyimide layer as the sensing surface. All of the micro-fabrication was compatible with the standard IC process. Experimental results indicated that the gauge factor of the proposed strain sensor was larger than 4.5, approximately 2.0 times greater than those of commercial gauges. The results also demonstrated that the gauge factor is small when the growth time of SWCNNs is lengthier, and the gauge factor is large when the line width of the serpentine pattern of SWCNNs is small.

Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

Directory of Open Access Journals (Sweden)

Qian Yong

2009-01-01

Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

Adhesion energy of single wall carbon nanotube loops on various substrates

Energy Technology Data Exchange (ETDEWEB)

Li, Tianjun [Université de Lyon, Laboratoire de Physique, ENS de Lyon, CNRS-46, Allée d' Italie, Lyon 69364 (France); Department of Physics, Shaoxing University, 508 Huancheng West Rd., Shaoxing 312000 (China); Ayari, Anthony [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Bellon, Ludovic, E-mail: ludovic.bellon@ens-lyon.fr [Université de Lyon, Laboratoire de Physique, ENS de Lyon, CNRS-46, Allée d' Italie, Lyon 69364 (France)

2015-04-28

The physics of adhesion of one-dimensional nano structures such as nanotubes, nano wires, and biopolymers on different substrates is of great interest for the study of biological adhesion and the development of nano electronics and nano mechanics. In this paper, we present force spectroscopy experiments of individual single wall carbon nanotube loops using a home-made interferometric atomic force microscope. Characteristic force plateaus during the peeling process allow the quantitative measurement of the adhesion energy per unit length on various substrates: graphite, mica, platinum, gold, and silicon. Moreover, using a time-frequency analysis of the deflection of the cantilever, we estimate the dynamic stiffness of the contact, providing more information on the nanotube configurations and its intrinsic mechanical properties.

Fabrication and electrochemical behavior of single-walled carbon nanotube/graphite-based electrode

International Nuclear Information System (INIS)

Moghaddam, Abdolmajid Bayandori; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Razavi, Taherehsadat; Riahi, Siavash; Rezaei-Zarchi, Saeed; Norouzi, Parviz

2009-01-01

An electrochemical method for determining the dihydroxybenzene derivatives on glassy carbon (GC) has been developed. In this method, the performance of a single-walled carbon nanotube (SWCNT)/graphite-based electrode, prepared by mixing SWCNTs and graphite powder, was described. The resulting electrode shows an excellent behavior for redox of 3,4-dihydroxybenzoic acid (DBA). SWCNT/graphite-based electrode presents a significant decrease in the overvoltage for DBA oxidation as well as a dramatic improvement in the reversibility of DBA redox behavior in comparison with graphite-based and glassy carbon (GC) electrodes. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) procedures performed for used SWCNTs

The electronic fine structure of 4-nitrophenyl functionalized single-walled carbon nanotubes

International Nuclear Information System (INIS)

Chakraborty, Amit K; Coleman, Karl S; Dhanak, Vinod R

2009-01-01

Controlling the electronic structure of carbon nanotubes (CNTs) is of great importance to various CNT based applications. Herein the electronic fine structure of single-walled carbon nanotube films modified with 4-nitrophenyl groups, produced following reaction with 4-nitrobenzenediazonium tetrafluoroborate, was investigated for the first time. Various techniques such as x-ray and ultra-violet photoelectron spectroscopy, and near edge x-ray absorption fine structure studies were used to explore the electronic structure, and the results were compared with the measured electrical resistances. A reduction in number of the π electronic states in the valence band consistent with the increased resistance of the functionalized nanotube films was observed.

Mechanical properties investigation on single-wall ZrO2 nanotubes: A finite element method with equivalent Poisson's ratio for chemical bonds

Science.gov (United States)

Yang, Xiao; Li, Huijian; Hu, Minzheng; Liu, Zeliang; Wärnå, John; Cao, Yuying; Ahuja, Rajeev; Luo, Wei

2018-04-01

A method to obtain the equivalent Poisson's ratio in chemical bonds as classical beams with finite element method was proposed from experimental data. The UFF (Universal Force Field) method was employed to calculate the elastic force constants of Zrsbnd O bonds. By applying the equivalent Poisson's ratio, the mechanical properties of single-wall ZrNTs (ZrO2 nanotubes) were investigated by finite element analysis. The nanotubes' Young's modulus (Y), Poisson's ratio (ν) of ZrNTs as function of diameters, length and chirality have been discussed, respectively. We found that the Young's modulus of single-wall ZrNTs is calculated to be between 350 and 420 GPa.

Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

International Nuclear Information System (INIS)

Sakamoto, Y.; Ishii, Y.; Kawasaki, S.

2016-01-01

Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

Energy Technology Data Exchange (ETDEWEB)

Sakamoto, Y.; Ishii, Y.; Kawasaki, S., E-mail: kawasaki.shinji@nitech.ac.jp [Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi (Japan)

2016-07-06

Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

Measurement of gas species, temperatures, char burnout, and wall heat fluxes in a 200-MW{sub e} lignite-fired boiler at different loads

Energy Technology Data Exchange (ETDEWEB)

Li, Zhengqi; Jing, Jianping; Liu, Guangkui; Chen, Zhichao; Liu, Chunlong [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China)

2010-04-15

We measured various operational parameters of a 200-MW{sub e}, wall-fired, lignite utility boiler under different loads. The parameters measured were gas temperature, gas species concentration, char burnout, component release rates (C, H and N), furnace temperature, heat flux, and boiler efficiency. Cold air experiments of a single burner were conducted in the laboratory. A double swirl flow pulverized-coal burner has two ring recirculation zones that start in the secondary air region of the burner. With increasing secondary air flow, the air flow axial velocity increases, the maximum values for the radial velocity, tangential velocity, and turbulence intensity all increase, and there are slight increases in the air flow swirl intensity and the recirculation zone size. With increasing load gas, the temperature and CO concentration in the central region of burner decrease, while O{sub 2} concentration, NO{sub x} concentration, char burnout, and component release rates of C, H, and N increase. Pulverized-coal ignites farther into the burner, in the secondary air region. Gas temperature, O{sub 2} concentration, NO{sub x} concentration, char burnout and component release rates of C, H, and N all increase. Furthermore, CO concentration varies slightly and pulverized-coal ignites closer. In the side wall region, gas temperature, O{sub 2} concentration, and NO{sub x} concentration all increase, but CO concentration varies only slightly. In the bottom row burner region the furnace temperature and heat flux increase appreciably, but the increase become more obvious in the middle and top row burner regions and in the burnout region. Compared with a 120-MW{sub e} load, the mean NO{sub x} emission at the air preheater exits for 190-MW{sub e} load increases from 589.5 mg/m{sup 3} (O{sub 2} = 6%) to 794.6 mg/m{sup 3} (O{sub 2} = 6%), and the boiler efficiency increases from 90.73% to 92.45%. (author)

Evaluation Logic of Main Control Board Fire Risk

Energy Technology Data Exchange (ETDEWEB)

Kang, Dae Il; Kim, Kilyoo; Lim, Ho Gon [KAERI, Daejeon (Korea, Republic of)

2015-05-15

The main control board (MCB) is defined as the collection of control panels inside the main control room (MCR) of a nuclear power plant (NPP). As the MCB has the control and instrumentation circuits of redundant trains for almost all plant systems, small fires within the control panels may be detrimental to the safe shutdown capability. A big fire affecting many panels in the MCB can cause a forced MCR abandonment of the operators as well as function failures or spurious operations of the control and instrumentation-related components. If the MCR cannot be habitable, a safe shutdown from outside the MCR can be achieved and maintained at an alternate shutdown panel electrically and physically independent from the MCR. Because the MCB consist of many electrical panels, it may have internal barriers between them to prevent a fire from spreading from its origin to neighboring locations. However, most MCBs of domestic NPPs do not have internal barriers within them. If the MCB cabinets are not separated by a double wall with an air gap, the fire propagation of an MCB panel fire cannot be ruled out. Recently, Joglar et al. proposed a new evaluation logic for the MCB panel fires and mentioned that an MCB fire can be divided into propagation and non-propagating fires for abandonment and non-abandonment fire scenarios. However, they did not present the details on the fire modeling approaches and probability formulas for the fire scenarios. In this paper, a decision tree for evaluating the risk of an MCB fire is proposed to systematically determine the fire scenarios in terms of the fire modeling approaches. This paper proposed a decision tree for evaluating the risk of an MCB fire to systematically determine the fire scenarios in terms of fire modeling approaches.

Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests.

Directory of Open Access Journals (Sweden)

Danny L Fry

Full Text Available In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha(-1, and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥ 56% in large patches (≥ 10 trees, and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

Reinforcement of single-walled carbon nanotube bundles by intertube bridging

Science.gov (United States)

Kis, A.; Csányi, G.; Salvetat, J.-P.; Lee, Thien-Nga; Couteau, E.; Kulik, A. J.; Benoit, W.; Brugger, J.; Forró, L.

2004-03-01

During their production, single-walled carbon nanotubes form bundles. Owing to the weak van der Waals interaction that holds them together in the bundle, the tubes can easily slide on each other, resulting in a shear modulus comparable to that of graphite. This low shear modulus is also a major obstacle in the fabrication of macroscopic fibres composed of carbon nanotubes. Here, we have introduced stable links between neighbouring carbon nanotubes within bundles, using moderate electron-beam irradiation inside a transmission electron microscope. Concurrent measurements of the mechanical properties using an atomic force microscope show a 30-fold increase of the bending modulus, due to the formation of stable crosslinks that effectively eliminate sliding between the nanotubes. Crosslinks were modelled using first-principles calculations, showing that interstitial carbon atoms formed during irradiation in addition to carboxyl groups, can independently lead to bridge formation between neighbouring nanotubes.

Hydrogen storage in single-walled carbon nanotubes: methods and results

International Nuclear Information System (INIS)

Poirier, E.; Chahine, R.; Tessier, A.; Cossement, D.; Lafi, L.; Bose, T.K.

2004-01-01

We present high sensitivity gravimetric and volumetric hydrogen sorption measurement systems adapted for in situ conditioning under high temperature and high vacuum. These systems, which allow for precise measurements on small samples and thorough degassing, are used for sorption measurements on carbon nanostructures. We developed one volumetric system for the pressure range 0-1 bar, and two gravimetric systems for 0-1 bar and 0-100 bars. The use of both gravimetric and volumetric methods allows for the cross-checking of the results. The accuracy of the systems has been determined from hydrogen absorption measurements on palladium. The accuracies of the 0-1 bar volumetric and gravimetric systems are about 10 μg and 20 μg respectively. The accuracy of the 0-100 bars gravimetric system is about 20 μg. Hydrogen sorption measurements on single-walled carbon nanotubes (SWNTs) and metal-incorporated- SWNTs are presented. (author)

Fire analog: a comparison between fire plumes and energy center cooling tower plumes

Energy Technology Data Exchange (ETDEWEB)

Orgill, M.M.

1977-10-01

Thermal plumes or convection columns associated with large fires are compared to thermal plumes from cooling towers and proposed energy centers to evaluate the fire analog concept. Energy release rates of mass fires are generally larger than for single or small groups of cooling towers but are comparable to proposed large energy centers. However, significant physical differences exist between cooling tower plumes and fire plumes. Cooling tower plumes are generally dominated by ambient wind, stability and turbulence conditions. Fire plumes, depending on burning rates and other factors, can transform into convective columns which may cause the fire behavior to become more violent. This transformation can cause strong inflow winds and updrafts, turbulence and concentrated vortices. Intense convective columns may interact with ambient winds to create significant downwind effects such as wakes and Karman vortex streets. These characteristics have not been observed with cooling tower plumes to date. The differences in physical characteristics between cooling tower and fire plumes makes the fire analog concept very questionable even though the approximate energy requirements appear to be satisfied in case of large energy centers. Additional research is suggested in studying the upper-level plume characteristics of small experimental fires so this information can be correlated with similar data from cooling towers. Numerical simulation of fires and proposed multiple cooling tower systems could also provide comparative data.

Broadband Spectroscopic Thermoacoustic Characterization of Single-Walled Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Daniel R. Bauer

2015-01-01

Full Text Available Carbon nanotubes have attracted interest as contrast agents for biomedical imaging because they strongly absorb electromagnetic radiation in the optical and microwave regions. This study applies thermoacoustic (TA imaging and spectroscopy to measure the frequency-dependent absorption profile of single-walled carbon nanotubes (SWNT in the ranges of 2.7–3.1 GHz and 7–9 GHz using two tunable microwave sources. Between 7 and 9 GHz, the peak TA signal for solutions containing semiconducting and metallic SWNTs increased monotonically with a slope of 1.75 AU/GHz (R2=0.95 and 2.8 AU/GHz (R2=0.93, respectively, relative to a water baseline. However, after compensating for the background signal from water, it was revealed that the TA signal from metallic SWNTs increased exponentially within this frequency band. Results suggest that TA imaging and spectroscopy could be a powerful tool for quantifying the absorption properties of SWNTs and optimizing their performance as contrast agents for imaging or heat sources for thermal therapy.

Optical absorption of zigzag single walled boron nitride nanotubes

Science.gov (United States)

Moradian, Rostam; Chegel, Raad; Behzad, Somayeh

2010-11-01

In a realistic three-dimensional model, optical matrix element and linear optical absorption of zigzag single walled boron nitride nanotubes (BNNTs) in the tight binding approximation are studied. In terms of absolute value of dipole matrix elements of the first three direct transitions at kz=0, we divided the zigzag BNNTs into three groups and investigated their optical absorption spectrum in energy ranges E7.5 eV. We found that in lower energies, E7.5 eV, their behaviors depend on their even or odd nanotube index. We also found that in the energy range 7

Mechanisms of tryptophan adsorption onto single-walled carbon nanotubes

International Nuclear Information System (INIS)

Zhou Jieping; Tan Jun; Xu Pengshou; Sheng Liusi; Pan Guoqiang

2011-01-01

Near edge X-ray absorption fine structure spectroscopy (NEXAFS) and synchrotron radiation photoelectron spectroscopy (SRPES) were employed to investigate the adsorption mechanism of tryptophan (Trp) onto single-walled carbon nanotubes (SWCNTs). The difference of the carbon K-edge NEXAFS spectra between Trp molecules and Trp-adsorbed SWCNTs shows that a significant interaction occurs among the SWCNTs and Trp molecules adsorbed. However, negligible changes in the peak profiles and energy positions of nitrogen K-edge imply that neither of the two nitrogen atoms in Trp molecule is involved in the interface interaction. A change of the shape of the main absorption peak at the oxygen K-edge reveals that O atoms of the C=O or C-O or both are likely involved in the interface interaction. The fact that the peak at about 529 eV at the O K-edge become sharper and stronger demonstrates that the O atom in the C=O participates in the interface interaction, which was confirmed by O1s SRPES spectrum. (authors)

Nonlinear analysis techniques of block masonry walls in nuclear power plants

International Nuclear Information System (INIS)

Hamid, A.A.; Harris, H.G.

1986-01-01

Concrete masonry walls have been used extensively in nuclear power plants as non-load bearing partitions serving as pipe supports, fire walls, radiation shielding barriers, and similar heavy construction separations. When subjected to earthquake loads, these walls should maintain their structural integrity. However, some of the walls do not meet design requirements based on working stress allowables. Consequently, utilities have used non-linear analysis techniques, such as the arching theory and the energy balance technique, to qualify such walls. This paper presents a critical review of the applicability of non-linear analysis techniques for both unreinforced and reinforced block masonry walls under seismic loading. These techniques are critically assessed in light of the performance of walls from limited available test data. It is concluded that additional test data are needed to justify the use of nonlinear analysis techniques to qualify block walls in nuclear power plants. (orig.)

The DNA hybridization assay using single-walled carbon nanotubes as ultrasensitive, long-term optical labels

International Nuclear Information System (INIS)

Hwang, Eung-Soo; Cao, Chengfan; Hong, Sanghyun; Jung, Hye-Jin; Cha, Chang-Yong; Choi, Jae-Boong; Kim, Young-Jin; Baik, Seunghyun

2006-01-01

Single walled carbon nanotubes (SWNTs) exhibit strong Raman signals as well as fluorescence emissions in the near infrared region. Such signals do not blink or photobleach under prolonged excitation, which is an advantage in optical nano-biomarker applications. In this paper, we present single-stranded DNA conjugated SWNT probes to locate a particular sequence of DNA within a complex genome. Chromosomal DNAs of human fibroblasts and Escherichia coli are used as a target and a control, respectively. Southern blotting, which uses photostable Raman signals of nanotubes instead of fluorescent dyes, demonstrates excellent sensitivity and specificity of the probes. The results show that SWNTs may be used as generic nano-biomarkers for the precise detection of specific kinds of genes

Impact of single-walled carbon nanotubes on the embryo: a brief review

Directory of Open Access Journals (Sweden)

Al Moustafa AE

2016-01-01

Full Text Available Ala-Eddin Al Moustafa,1–4 Etienne Mfoumou,5 Dacian E Roman,3 Vahe Nerguizian,6 Anas Alazzam,7 Ion Stiharu,3 Amber Yasmeen8 1College of Medicine & Biomedical Research Centre, Qatar University, Doha, Qatar; 2Oncology Department, McGill University, 3Mechanical and Industrial Engineering Department, Concordia University, Montreal, QC, Canada; 4Syrian Research Cancer Centre of the Syrian Society against Cancer, Aleppo, Syria; 5Nova Scotia Community College, Dartmouth, NS, 6École de Technologie Supérieure, Montreal, QC, Canada; 7Department of Mechanical Engineering, Khalifa University, Abu Dhabi, UAE; 8Segal Cancer Centre, Lady Davis Institute for Medical Research of the Sir Mortimer B. Davis-Jewish General Hospital, Montreal, QC, Canada Abstract: Carbon nanotubes (CNTs are considered one of the most interesting materials in the 21st century due to their unique physiochemical characteristics and applicability to various industrial products and medical applications. However, in the last few years, questions have been raised regarding the potential toxicity of CNTs to humans and the environment; it is believed that the physiochemical characteristics of these materials are key determinants of CNT interaction with living cells and hence determine their toxicity in humans and other organisms as well as their embryos. Thus, several recent studies, including ours, pointed out that CNTs have cytotoxic effects on human and animal cells, which occur via the alteration of key regulator genes of cell proliferation, apoptosis, survival, cell–cell adhesion, and angiogenesis. Meanwhile, few investigations revealed that CNTs could also be harmful to the normal development of the embryo. In this review, we will discuss the toxic role of single-walled CNTs in the embryo, which was recently explored by several groups including ours. Keywords: single-walled carbon nanotubes, embryo, toxicity

Structural profiling and biological performance of phospholipid-hyaluronan functionalized single-walled carbon nanotubes

DEFF Research Database (Denmark)

Dvash, Ram; Khatchatouriants, Artium; Solmesky, Leonardo J

2013-01-01

In spite of significant insolubility and toxicity, carbon nanotubes (CNTs) erupt into the biomedical research, and create an increasing interest in the field of nanomedicine. Single-walled CNTs (SWCNTs) are highly hydrophobic and have been shown to be toxic while systemically administrated. Thus...... an inflammatory response in macrophages as evidenced by the cytokine profiling and the use of image-based high-content analysis approach in contrast to non-modified CNTs. In addition, systemic administration of CNT-PL-HA into healthy C57BL/6 mice did not alter the total number of leukocytes nor increased liver...

The effect of atomic hydrogen adsorption on single-walled carbon nano tubes properties

International Nuclear Information System (INIS)

Jalili, S.; Majidi, R.

2007-01-01

We investigated the adsorption of hydrogen atoms on metallic single-walled carbon nano tubes using ab initio molecular dynamics method. It was found that the geometric structures and the electronic properties of hydrogenated SWNTs can be strongly changed by varying hydrogen coverage. The circular cross sections of the CNTs were changed with different hydrogen coverage. When hydrogen is chemisorbed on the surface of the carbon nano tube, the energy gap will be appeared. This is due to the degree of the Sp 3 hybridization, and the hydrogen coverage can control the band gap of the carbon nano tube

Observation and Characterization of Fragile Organometallic Molecules Encapsulated in Single-Wall Carbon Nanotubes

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Daisuke Ogawa

2014-01-01

Full Text Available Thermally fragile tris(η5-cyclopentadienylerbium (ErCp3 molecules are encapsulated in single-wall carbon nanotubes (SWCNTs with high yield. We realized the encapsulation of ErCp3 with high filling ratio by using high quality SWCNTs at an optimized temperature under higher vacuum. Structure determination based on high-resolution transmission electron microscope observations together with the image simulations reveals the presence of almost free rotation of each ErCp3 molecule in SWCNTs. The encapsulation is also confirmed by X-ray diffraction. Trivalent character of Er ions (i.e., Er3+ is confirmed by X-ray absorption spectrum.

Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

International Nuclear Information System (INIS)

Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

2009-01-01

Free standing films of single-wall carbon nanotubes were irradiated with energetic N + and C 4+ ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C 4+ irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes

Optical properties of graphene nanoribbons encapsulated in single-walled carbon nanotubes.

Science.gov (United States)

Chernov, Alexander I; Fedotov, Pavel V; Talyzin, Alexandr V; Suarez Lopez, Inma; Anoshkin, Ilya V; Nasibulin, Albert G; Kauppinen, Esko I; Obraztsova, Elena D

2013-07-23

We report the photoluminescence (PL) from graphene nanoribbons (GNRs) encapsulated in single-walled carbon nanotubes (SWCNTs). New PL spectral features originating from GNRs have been detected in the visible spectral range. PL peaks from GNRs have resonant character, and their positions depend on the ribbon geometrical structure in accordance with the theoretical predictions. GNRs were synthesized using confined polymerization and fusion of coronene molecules. GNR@SWCNTs material demonstrates a bright photoluminescence both in infrared (IR) and visible regions. The photoluminescence excitation mapping in the near-IR spectral range has revealed the geometry-dependent shifts of the SWCNT peaks (up to 11 meV in excitation and emission) after the process of polymerization of coronene molecules inside the nanotubes. This behavior has been attributed to the strain of SWCNTs induced by insertion of the coronene molecules.

Induced superhydrophobic and antimicrobial character of zinc metal modified ceramic wall tile surfaces

Science.gov (United States)

Özcan, Selçuk; Açıkbaş, Gökhan; Çalış Açıkbaş, Nurcan

2018-04-01

Hydrophobic surfaces are also known to have antimicrobial effect by restricting the adherence of microorganisms. However, ceramic products are produced by high temperature processes resulting in a hydrophilic surface. In this study, an industrial ceramic wall tile glaze composition was modified by the inclusion of metallic zinc powder in the glaze suspension applied on the pre-sintered wall tile bodies by spraying. The glazed tiles were gloss fired at industrially applicable peak temperatures ranging from 980 °C to 1100 °C. The fired tile surfaces were coated with a commercial fluoropolymer avoiding water absorption. The surfaces were characterized with SEM, EDS, XRD techniques, roughness, sessile water drop contact angle, surface energy measurements, and standard antimicrobial tests. The surface hydrophobicity and the antimicrobial activity results were compared with that of unmodified, uncoated gloss fired wall tiles. A superhydrophobic contact angle of 150° was achieved at 1000 °C peak temperature due to the formation of micro-structured nanocrystalline zinc oxide granules providing a specific surface topography. At higher peak temperatures the hydrophobicity was lost as the specific granular surface topography deteriorated with the conversion of zinc oxide granules to the ubiquitous willemite crystals embedded in the glassy matrix. The antimicrobial efficacy also correlated with the hydrophobic character.

Single-Walled Carbon-Nanotubes-Based Organic Memory Structures

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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.

Empirical Equation Based Chirality (n, m Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

Directory of Open Access Journals (Sweden)

Md Shamsul Arefin

2012-12-01

Full Text Available This work presents a technique for the chirality (n, m assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n, m with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot.

Empirical Equation Based Chirality (n, m) Assignment of Semiconducting Single Wall Carbon Nanotubes from Resonant Raman Scattering Data

Science.gov (United States)

Arefin, Md Shamsul

2012-01-01

This work presents a technique for the chirality (n, m) assignment of semiconducting single wall carbon nanotubes by solving a set of empirical equations of the tight binding model parameters. The empirical equations of the nearest neighbor hopping parameters, relating the term (2n− m) with the first and second optical transition energies of the semiconducting single wall carbon nanotubes, are also proposed. They provide almost the same level of accuracy for lower and higher diameter nanotubes. An algorithm is presented to determine the chiral index (n, m) of any unknown semiconducting tube by solving these empirical equations using values of radial breathing mode frequency and the first or second optical transition energy from resonant Raman spectroscopy. In this paper, the chirality of 55 semiconducting nanotubes is assigned using the first and second optical transition energies. Unlike the existing methods of chirality assignment, this technique does not require graphical comparison or pattern recognition between existing experimental and theoretical Kataura plot. PMID:28348319

Synthesis of high quality single-walled carbon nanotubes via a catalytic layer reinforced by self-assembled monolayers

International Nuclear Information System (INIS)

Adhikari, Prashanta Dhoj; Song, Wooseok; Cha, Myoung-Jun; Park, Chong-Yun

2013-01-01

This work reports the synthesis of high quality single-walled carbon nanotubes (SWCNT) using a catalytic layer reinforced by self-assembled monolayers (SAM). Amine-SAM was introduced on a SiO 2 /Si substrate and then an iron nanoparticles solution was dropped on the substrate by spin-coating. This catalytic template was used to grow carbon nanotubes by chemical vapor deposition and the synthesized SWCNT were observed to be prominent, based on the size distribution. Highly dense SWCNT with a diameter of about 1.1-1.2 nm were produced at 800-850 °C. Moreover, the diameter distribution of the SWCNT was more selective at a growth temperature of 900 °C. These findings provide important insights for a SAM support layer that can play the role as a restriction for the agglomeration of iron catalyst and is promising for the synthesis of high quality SWCNT. - Highlights: • Fe nanoparticles on self-assembled monolayers (SAM) containing template is underlined. • Its catalytic behavior to synthesis single-walled carbon nanotubes is studied. • The role of SAM on catalytic template is explored

Purity and Defect Characterization of Single-Wall Carbon Nanotubes Using Raman Spectroscopy

Directory of Open Access Journals (Sweden)

Yasumitsu Miyata

2011-01-01

Full Text Available We investigated the purity and defects of single-wall carbon nanotubes (SWCNTs produced by various synthetic methods including chemical vapor deposition, arc discharge, and laser ablation. The SWCNT samples were characterized using scanning electron microscopy (SEM, thermogravimetric analysis (TGA, and Raman spectroscopy. Quantitative analysis of SEM images suggested that the G-band Raman intensity serves as an index for the purity. By contrast, the intensity ratio of G-band to D-band (G/D ratio reflects both the purity and the defect density of SWCNTs. The combination of G-band intensity and G/D ratio is useful for a quick, nondestructive evaluation of the purity and defect density of a SWCNT sample.

Fire performance of multi-storey wooden facades

Directory of Open Access Journals (Sweden)

Östman Birgit A.-L.

2013-11-01

Full Text Available Two series of full scale fire tests of wooden facades according to the Swedish test SP Fire 105 are presented, one series for different shares of untreated wood (partial wood and structural fire protection with a fire shield above the window and another series for fire retardant treated, FRT, wood. The results are compared with data from the Single Burning Item test and the cone calorimeter. For FRT wood, the need for verification of the weather durability of the treatment is stressed and a new European technical specification CEN/TS 15912 presented. The need to use fire stops behind multi-storey façade claddings to avoid fire spread in the cavities is underlined and the possibilities of fire safety design with sprinklers is briefly presented.

Fire spread simulation of a full scale cable tunnel

International Nuclear Information System (INIS)

Huhtanen, R.

1999-11-01

A fire simulation of a full scale tunnel was performed by using the commercial code EFFLUENT as the simulation platform. Estimation was made for fire spread on the stacked cable trays, possibility of fire spread to the cable trays on the opposite wall of the tunnel, detection time of smoke detectors in the smouldering phase and response of sprinkler heads in the flaming phase. According to the simulation, the rise of temperature in the smouldering phase is minimal, only of the order 1 deg C. The estimates of optical density of smoke show that normal smoke detectors should give an alarm within 2-4 minutes from the beginning of the smouldering phase, depending on the distance to the detector (in this case it was assumed that the thermal source connected to the smoke source was 50 W). The flow conditions at smoke detectors may be challenging, because the velocity magnitude is rather low at this phase. At 4 minutes the maximum velocity at the detectors is 0.12 m/s. During the flaming phase (beginning from 11 minutes) fire spreads on the stacked cable trays in an expected way, although the ignition criterion seems to perform poorly when ignition of new objects is considered. The Upper cable trays are forced to ignite by boundary condition definitions according to the experience found from ti full scale experiment and an earlier simulation. After 30 minutes the hot layer in the room becomes so hot that it speeds up the fire spread and the rate of heat release of burning objects. Further, the hot layer ignites the cable trays on the opposite wall of the tunnel after 45 minutes. It is estimated that the sprinkler heads would be activated at 20-22 minutes near the fire source and at 24-28 minutes little further from the fire source when fast sprinkler heads are used. The slow heads are activated between 26-32 minutes. (orig.)

Nuclear hazard/fire hazard: an elusive and important linkage

International Nuclear Information System (INIS)

Mariani, L.P.

1977-01-01

The Brown's Ferry Fire signaled a yellow alert for nuclear safety related fire protection and showed that fire protection engineering must be regarded as a bona fide nuclear discipline. A single-failure design criteria violation resulted in fire damage to plant systems and plant instrumentation. Localized damage lead to significant consequences. Although the linkage between fire and nuclear hazard is termed subtle, effective standards and criteria development must be aimed to future plants. Combined fire protection and nuclear engineering inspections are planned

Modeling urban fire growth

International Nuclear Information System (INIS)

Waterman, T.E.; Takata, A.N.

1983-01-01

The IITRI Urban Fire Spread Model as well as others of similar vintage were constrained by computer size and running costs such that many approximations/generalizations were introduced to reduce program complexity and data storage requirements. Simplifications were introduced both in input data and in fire growth and spread calculations. Modern computational capabilities offer the means to introduce greater detail and to examine its practical significance on urban fire predictions. Selected portions of the model are described as presently configured, and potential modifications are discussed. A single tract model is hypothesized which permits the importance of various model details to be assessed, and, other model applications are identified

Elemental Characterization of Single-Wall Carbon Nanotube Certified Reference Material by Neutron and Prompt gamma Activation Analysis

Czech Academy of Sciences Publication Activity Database

Kučera, Jan; Bennett, J. W.; Oflaz, R.; Paul, R. L.; De Nadai Fernandes, E. A.; Kubešová, Marie; Bacchi, M. A.; Stopic, A. J.; Sturgeon, R. E.; Grinberg, P.

2015-01-01

Roč. 87, č. 7 (2015), s. 3699-3705 ISSN 0003-2700 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2011019 Institutional support: RVO:61389005 Keywords : Neutron Activation Analyses * nanotechnology * Carbon nanotubes * Chemical activation * Single-walled carbon nanotubes (SWCN) Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 5.886, year: 2015

Ab initio studies of vacancies in (8,0) and (8,8) single-walled carbon and boron nitride nanotubes

CSIR Research Space (South Africa)

Mashapa, MG

2012-09-01

Full Text Available -1 Journal of Nanoscience and Nanotechnology Vol. 12, 7030?7036, 2012 Ab Initio Studies of Vacancies in (8,0) and (8,8) Single-Walled Carbon and Boron Nitride NanotubesAb M. G. Mashapa 1, 2, *, N. Chetty 2, and S. Sinha Ray 1, 3 1 DST...

Design criteria document, Fire Protection Task, K Basin Essential Systems Recovery, Project W-405

International Nuclear Information System (INIS)

Johnson, B.H.

1994-01-01

The K Basin were constructed in the early 1950's with a 20 year design life. The K Basins are currently in their third design life and are serving as a near term storage facility for irradiated N Reactor fuel until an interim fuel storage solution can be implemented. In April 1994, Project W-405, K Basin Essential Systems Recovery, was established to address (among other things) the immediate fire protection needs of the 100K Area. A Fire Barrier Evaluation was performed for the wall between the active and inactive areas of the 105KE and 105KW buildings. This evaluation concludes that the wall is capable of being upgraded to provide an equivalent level of fire resistance as a qualified barrier having a fire resistance rating of 2 hours. The Fire Protection Task is one of four separate Tasks included within the scope of Project W405, K Basin Essential systems Recovery. The other three Tasks are the Water Distribution System Task, the Electrical System Task, and the Maintenance Shop/Support Facility Task. The purpose of Project W-405's Fire Protection Task is to correct Life Safety Code (NFPA 101) non-compliances and to provide fire protection features in Buildings 105KE, 105KW and 190KE that are essential for assuring the safe operation and storage of spent nuclear fuel at the 100K Area Facilities' Irradiated Fuel Storage Basins (K Basins)

Single-walled carbon nanotube electromechanical switching behavior with shoulder slip

Science.gov (United States)

Ryan, Peter; Wu, Yu-Chiao; Somu, Sivasubramanian; Adams, George; McGruer, Nicol

2011-04-01

Several electromechanical devices, each consisting of a small bundle of single-walled carbon nanotubes suspended over an actuation electrode, have been fabricated and operated electrically. The nanotubes are assembled on the electrodes using dielectrophoresis, a potential high-rate nanomanufacturing process. A large decrease in the threshold voltage was seen after the first actuation. This is a result of the nanotubes sliding inward on their supports as they are pulled down toward the actuation electrode, leaving slack in the nanotube bundle for subsequent actuations. The electrical measurements agree well with an electromechanical model that uses a literature-reported value of the shear stress between the nanotubes and the SiO2 shoulders. Electrical measurements were performed in dry nitrogen as a large build-up of contamination was seen when the measurements were performed in lab air. We present measurements as well as a detailed mechanics model that support the interpretation of the data.

Single-walled carbon nanotube electromechanical switching behavior with shoulder slip

International Nuclear Information System (INIS)

Ryan, Peter; Wu, Yu-Chiao; Somu, Sivasubramanian; Adams, George; McGruer, Nicol

2011-01-01

Several electromechanical devices, each consisting of a small bundle of single-walled carbon nanotubes suspended over an actuation electrode, have been fabricated and operated electrically. The nanotubes are assembled on the electrodes using dielectrophoresis, a potential high-rate nanomanufacturing process. A large decrease in the threshold voltage was seen after the first actuation. This is a result of the nanotubes sliding inward on their supports as they are pulled down toward the actuation electrode, leaving slack in the nanotube bundle for subsequent actuations. The electrical measurements agree well with an electromechanical model that uses a literature-reported value of the shear stress between the nanotubes and the SiO 2 shoulders. Electrical measurements were performed in dry nitrogen as a large build-up of contamination was seen when the measurements were performed in lab air. We present measurements as well as a detailed mechanics model that support the interpretation of the data.

On the Adequacy of API 521 Relief-Valve Sizing Method for Gas-Filled Pressure Vessels Exposed to Fire

Directory of Open Access Journals (Sweden)

Anders Andreasen

2018-03-01

Full Text Available In this paper, the adequacy of the legacy API 521 guidance on pressure relief valve (PRV sizing for gas-filled vessels subjected to external fire is investigated. Multiple studies show that in many cases, the installation of a PRV offers little or no protection—therefore provides an unfounded sense of security. Often the vessel wall will be weakened by high temperatures, before the PRV relieving pressure is reached. In this article, a multiparameter study has been performed taking into consideration various vessel sizes, design pressures (implicitly vessel wall thickness, vessel operating pressure, fire type (pool fire or jet fire by applying the methodology presented in the Scandpower guideline. A transient thermomechanical response analysis has been carried out to accurately determine vessel rupture times. It is demonstrated that only vessels with relatively thick walls, as a result of high design pressures, benefit from the presence of a PRV, while for most cases no appreciable increase in the vessel survival time beyond the onset of relief is observed. For most of the cases studied, vessel rupture will occur before the relieving pressure of the PRV is reached.

Integrating fire management analysis into land management planning

Science.gov (United States)

Thomas J. Mills

1983-01-01

The analysis of alternative fire management programs should be integrated into the land and resource management planning process, but a single fire management analysis model cannot meet all planning needs. Therefore, a set of simulation models that are analytically separate from integrated land management planning models are required. The design of four levels of fire...

46 CFR 28.820 - Fire pumps, fire mains, fire hydrants, and fire hoses.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.820 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel must be equipped with a self-priming, power driven fire...

Investigating interfacial contact configuration and behavior of single-walled carbon nanotube-based nanodevice with atomistic simulations

Energy Technology Data Exchange (ETDEWEB)

Cui, Jianlei, E-mail: cjlxjtu@mail.xjtu.edu.cn; Zhang, Jianwei [Xi’an Jiaotong University, State Key Laboratory for Manufacturing Systems Engineering (China); He, Xiaoqiao, E-mail: bcxqhe@cityu.edu.hk [City University of Hong Kong, Department of Architecture and Civil Engineering (Hong Kong); Mei, Xuesong; Wang, Wenjun [Xi’an Jiaotong University, State Key Laboratory for Manufacturing Systems Engineering (China); Yang, Xinju [Fudan University, State Key Laboratory of Surface Physics and Department of Physics (China); Xie, Hui; Yang, Lijun; Wang, Yang [Harbin Institute of Technology, State Key Laboratory of Robotics and Systems (China)

2017-03-15

Carbon nanotubes (CNTs), including single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs), are considered to be the promising candidates for next-generation interconnects with excellent physical and chemical properties ranging from ultrahigh mechanical strength, to electrical properties, to thermal conductivity, to optical properties, etc. To further study the interfacial contact configurations of SWNT-based nanodevice with a 13.56-Å diameter, the corresponding simulations are carried out with the molecular dynamic method. The nanotube collapses dramatically into the surface with the complete collapse on the Au/Ag/graphite electrode surface and slight distortion on the Si/SiO{sub 2} substrate surface, respectively. The related dominant mechanism is studied and explained. Meanwhile, the interfacial contact configuration and behavior, depended on other factors, are also analyzed in this article.

On-Chip Chemical Self-Assembly of Semiconducting Single-Walled Carbon Nanotubes (SWNTs) : Toward Robust and Scale Invariant SWNTs Transistors

NARCIS (Netherlands)

Derenskyi, Vladimir; Gomulya, Widianta; Talsma, Wytse; Salazar-Rios, Jorge Mario; Fritsch, Martin; Nirmalraj, Peter; Riel, Heike; Allard, Sybille; Scherf, Ullrich; Loi, Maria A.

2017-01-01

In this paper, the fabrication of carbon nanotubes field effect transistors by chemical self-assembly of semiconducting single walled carbon nanotubes (s-SWNTs) on prepatterned substrates is demonstrated. Polyfluorenes derivatives have been demonstrated to be effective in selecting s-SWNTs from raw

Sequence Dependent Interactions Between DNA and Single-Walled Carbon Nanotubes

Science.gov (United States)

Roxbury, Daniel

It is known that single-stranded DNA adopts a helical wrap around a single-walled carbon nanotube (SWCNT), forming a water-dispersible hybrid molecule. The ability to sort mixtures of SWCNTs based on chirality (electronic species) has recently been demonstrated using special short DNA sequences that recognize certain matching SWCNTs of specific chirality. This thesis investigates the intricacies of DNA-SWCNT sequence-specific interactions through both experimental and molecular simulation studies. The DNA-SWCNT binding strengths were experimentally quantified by studying the kinetics of DNA replacement by a surfactant on the surface of particular SWCNTs. Recognition ability was found to correlate strongly with measured binding strength, e.g. DNA sequence (TAT)4 was found to bind 20 times stronger to the (6,5)-SWCNT than sequence (TAT)4T. Next, using replica exchange molecular dynamics (REMD) simulations, equilibrium structures formed by (a) single-strands and (b) multiple-strands of 12-mer oligonucleotides adsorbed on various SWCNTs were explored. A number of structural motifs were discovered in which the DNA strand wraps around the SWCNT and 'stitches' to itself via hydrogen bonding. Great variability among equilibrium structures was observed and shown to be directly influenced by DNA sequence and SWCNT type. For example, the (6,5)-SWCNT DNA recognition sequence, (TAT)4, was found to wrap in a tight single-stranded right-handed helical conformation. In contrast, DNA sequence T12 forms a beta-barrel left-handed structure on the same SWCNT. These are the first theoretical indications that DNA-based SWCNT selectivity can arise on a molecular level. In a biomedical collaboration with the Mayo Clinic, pathways for DNA-SWCNT internalization into healthy human endothelial cells were explored. Through absorbance spectroscopy, TEM imaging, and confocal fluorescence microscopy, we showed that intracellular concentrations of SWCNTs far exceeded those of the incubation

Thermodynamics for the Formation of Double-Stranded DNA-Single-Walled Carbon Nanotube Hybrids.

Science.gov (United States)

Shiraki, Tomohiro; Tsuzuki, Akiko; Toshimitsu, Fumiyuki; Nakashima, Naotoshi

2016-03-24

For the first time, the thermodynamics are described for the formation of double-stranded DNA (ds-DNA)-single-walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds-DNAs d(A)20 -d(T)20 and nuclear factor (NF)-κB decoy. UV/Vis/near-IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single-stranded DNAs (ss-DNAs), including d(A)20 and d(T)20, are also used for comparison. The d(A)20-d(T)20 shows a drastic change in its thermodynamic parameters around the melting temperature (Tm ) of the DNA oligomer. No such Tm dependency was measured, owing to high Tm in the NF-κB decoy DNA and no Tm in the ss-DNA. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phosphatidylserine targeted single-walled carbon nanotubes for photothermal ablation of bladder cancer

Science.gov (United States)

Virani, Needa A.; Davis, Carole; McKernan, Patrick; Hauser, Paul; Hurst, Robert E.; Slaton, Joel; Silvy, Ricardo P.; Resasco, Daniel E.; Harrison, Roger G.

2018-01-01

Bladder cancer has a 60%-70% recurrence rate most likely due to any residual tumour left behind after a transurethral resection (TUR). Failure to completely resect the cancer can lead to recurrence and progression into higher grade tumours with metastatic potential. We present here a novel therapy to treat superficial tumours with the potential to decrease recurrence. The therapy is a heat-based approach in which bladder tumour specific single-walled carbon nanotubes (SWCNTs) are delivered intravesically at a very low dose (0.1 mg SWCNT per kg body weight) followed 24 h later by a short 30 s treatment with a 360° near-infrared light that heats only the bound nanotubes. The energy density of the treatment was 50 J cm-2, and the power density that this treatment corresponds to is 1.7 W cm-2, which is relatively low. Nanotubes are specifically targeted to the tumour via the interaction of annexin V (AV) and phosphatidylserine, which is normally internalised on healthy tissue but externalised on tumours and the tumour vasculature. SWCNTs are conjugated to AV, which binds specifically to bladder cancer cells as confirmed in vitro and in vivo. Due to this specific localisation, NIR light can be used to heat the tumour while conserving the healthy bladder wall. In a short-term efficacy study in mice with orthotopic MB49 murine bladder tumours treated with the SWCNT-AV conjugate and NIR light, no tumours were visible on the bladder wall 24 h after NIR light treatment, and there was no damage to the bladder. In a separate survival study in mice with the same type of orthotopic tumours, there was a 50% cure rate at 116 days when the study was ended. At 116 days, no treatment toxicity was observed, and no nanotubes were detected in the clearance organs or bladder.

Evaluation of Gas Reburning and Low N0x Burners on a Wall Fired Boiler

Energy Technology Data Exchange (ETDEWEB)

None

1998-07-01

Under the U.S. Department of Energy's Clean Coal Technology Program (Round 3), a project was completed to demonstrate control of boiler NOX emissions and to a lesser degree, due to coal replacement, SO2 emissions. The project involved combining Gas Reburning with Low NOX Burners (GR-LNB) on a coal-fired electric utility boiler to determine if high levels of NO, reduction (70VO) could be achieved. Sponsors of the project included the U.S. Depatiment of Energy, the Gas Research Institute, Public Service Company of Colorado, Colorado Interstate Gas, Electric Power Research Institute, and the Energy and Environmental Research Corporation. The GR-LNB demonstration was petformed on Public Service Company of Colorado's (PSCO) Cherokee Unit #3, located in Denver, Colorado. This unit is a 172 MW~ wall-fired boiler that uses Colorado bituminous, low-sulfur coal. It had a baseline NO, emission level of 0.73 lb/1 OG Btu using conventional burners. Low NOX burners are designed to yield lower NOX emissions than conventional burners. However, the NOX control achieved with this technique is limited to 30-50Y0. Also, with LNBs, CO emissions can increase to above acceptable standards. Gas Reburning (GR) is designed to reduce NO, in the flue gas by staged fuel combustion. This technology involves the introduction of' natural gas into the hot furnace flue gas stream. When combined, GR and LNBs minimize NOX emissions and maintain acceptable levels of CO emissions. A comprehensive test program was completed, operating over a wide range of boiler conditions. Over 4,000 hours of operation were achieved, providing substantial data. Measurements were taken to quantify reductions in NOX emissions, the impact on boiler equipment and operability and factors influencing costs. The GR-LNB technology achieved good NO, emission reductions and the goals of the project were achieved. Although the performance of the low NOX burners (supplied by others) was less than expected, a NOX

Intraperitoneal Injection Is Not a Suitable Administration Route for Single-Walled Carbon Nanotubes in Biomedical Applications

OpenAIRE

Liu, Xudong; Guo, Qing; Zhang, Yuchao; Li, Jinquan; Li, Rui; Wu, Yang; Ma, Ping; Yang, Xu

2016-01-01

Given the extensive application of carbon nanotubes (CNTs) in biomedical fields, there is increasing concern regarding unintentional health impacts. Research into safe usage is therefore increasingly necessary. This study investigated the responses of the mouse brain to single-walled CNTs (SWCNTs) delivered via intraperitoneal (IP) injection and compared these results with the previous study where SWCNTs were delivered via intravenous (IV) injection so as to explore which administration route...

In vitro evaluation of three-dimensional single-walled carbon nanotube composites for bone tissue engineering.

Science.gov (United States)

Gupta, Ashim; Main, Benjamin J; Taylor, Brittany L; Gupta, Manu; Whitworth, Craig A; Cady, Craig; Freeman, Joseph W; El-Amin, Saadiq F

2014-11-01

The purpose of this study was to develop three-dimensional single-walled carbon nanotube composites (SWCNT/PLAGA) using 10-mg single-walled carbon nanotubes (SWCNT) for bone regeneration and to determine the mechanical strength of the composites, and to evaluate the interaction of MC3T3-E1 cells via cell adhesion, growth, survival, proliferation, and gene expression. PLAGA (polylactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated, characterized, and mechanical testing was performed. MC3T3-E1 cells were seeded and cell adhesion/morphology, growth/survival, proliferation, and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, nonstressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared with PLAGA. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration, for bone tissue engineering, and are promising for orthopedic applications as they possess the combined effect of increased mechanical strength, cell proliferation, and gene expression. © 2014 Wiley Periodicals, Inc.

Self-Assembled CNT-Polymer Hybrids in Single-Walled Carbon Nanotubes Dispersed Aqueous Triblock Copolymer Solutions

Science.gov (United States)

Vijayaraghavan, D.; Manjunatha, A. S.; Poojitha, C. G.

2018-04-01

We have carried out scanning electron microscopy (SEM), differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), electrical conductivity, and 1H NMR studies as a function of temperature on single-walled carbon nanotubes (SWCNTs) dispersed aqueous triblock copolymer (P123) solutions. The single-walled carbon nanotubes in this system aggregate to form bundles, and the bundles aggregate to form net-like structures. Depending on the temperature and phases of the polymer, this system exhibits three different self-assembled CNT-polymer hybrids. We find CNT-unimer hybrid at low temperatures, CNT-micelle hybrid at intermediate temperatures wherein the polymer micelles are adsorbed in the pores of the CNT nets, and another type of CNT-micelle hybrid at high temperatures wherein the polymer micelles are adsorbed on the surface of the CNT bundles. Our DSC thermogram showed two peaks related to these structural changes in the CNT-polymer hybrids. Temperature dependence of the 1H NMR chemical shifts of the molecular groups of the polymer and the AC electrical conductivity of the composite also showed discontinuous changes at the temperatures at which the CNT-polymer hybrid's structural changes are seen. Interestingly, for a higher CNT concentration (0.5 wt.%) in the system, the aggregated polymer micelles adsorbed on the CNTs exhibit cone-like and cube-like morphologies at the intermediate and at high temperatures respectively.

Relationships among the structural topology, bond strength, and mechanical properties of single-walled aluminosilicate nanotubes.

Science.gov (United States)

Liou, Kai-Hsin; Tsou, Nien-Ti; Kang, Dun-Yen

2015-10-21

Carbon nanotubes (CNTs) are regarded as small but strong due to their nanoscale microstructure and high mechanical strength (Young's modulus exceeds 1000 GPa). A longstanding question has been whether there exist other nanotube materials with mechanical properties as good as those of CNTs. In this study, we investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. This method allowed for simulated mechanical tests (tensile, bending, and torsion) with minimum computational resources for deducing their Young's modulus and shear modulus. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. The proposed methodology proved effective in rationalizing differences in the mechanical properties of AlSiNTs and SWCNTs. Furthermore, this approach could be applied to the exploration of new high-strength nanotube materials.

Antenna-coupled terahertz radiation from joule-heated single-wall carbon nanotubes

Directory of Open Access Journals (Sweden)

M. Muthee

2011-12-01

Full Text Available In this letter an experimental method is introduced that allows detection of terahertz (THz radiation from arrays of joule-heated Single-Walled Carbon Nanotubes (SWCNTs, by coupling this radiation through integrated antennas and a silicon lens. The radiation forms a diffraction-limited beam with a total maximum radiated power of 450 nW, significantly greater than the power estimated from Nyquist thermal noise (8 nW. The physical radiation process is unknown at this stage, but possible explanations for the high radiated power are discussed briefly. The emission has a typical bandwidth of 1.2 THz and can be tuned to different frequencies by changing the dimensions of the antennas. Arrays of the devices could be integrated in CMOS integrated circuits, and find application in THz systems, such as in near-range medical imaging.

Photo-induced thermoelectric response in suspended single-walled carbon nanotube films

Science.gov (United States)

St-Antoine, Benoit; Menard, David; Martel, Richard

2010-03-01

A study was carried out on the position dependent photovoltage of suspended single-walled carbon nanotube films in vacuum. The photoresponse of such films was found to be driven by a thermal mechanism, rather than by direct photoexcitation of carriers. [1] A model was developed which establishes a relation between the photoresponse profile and the local Seebeck coefficient of the film, thus opening up new perspectives for material characterization. The technique was demonstrated by monitoring the doping changes in the nanotube films obtained by successive current conditioning steps. Since the Seebeck coefficient of carbon nanotubes spans a considerable range depending on their doping state, the photovoltage amplitude can be tuned and large responses have been measured (up to 0.75mV for 1.2mW). [4pt] [1] B. St-Antoine et al. Nano Lett. 9, 3503 (2009)

Band Gap Changes Of Single Walled Carbon Nanotubes Under Uniaxial Strain

International Nuclear Information System (INIS)

Dereli, G.

2010-01-01

The study of the band gap variation with mechanical deformation is important in manipulations of Single Walled Carbon Nanotubes (SWCNT). In this study we investigated the electronic band structure and the mechanical properties of (12,0) and (13,0) SWCNTs under the effect of uniaxial strain. Electronic and mechanical properties are studied using a parallel, order N, tight-binding molecular dynamics (O(N) TBMD) simulation code designed by G. Dereli et. al. We showed the effect of uniaxial strain on the variations of band gaps and the total energy per atom of (12,0) and (13,0) SWCNTs. We calculated Young's modulus and the Poisson ratio of these SWCNTs. The research reported here was supported through the Yildiz Technical University Research Found Project No: 24-01-01-04. Simulations are performed in parallel environment at Carbon Nanotube Simulation Laboratory of Yildiz Technical University.

The adsorption of L-phenylalanine on oxidized single-walled carbon nanotubes.

Science.gov (United States)

Piao, Lingyu; Liu, Quanrun; Li, Yongdan; Wang, Chen

2009-02-01

A simple and green approach was proceeded to obtain a stable single-walled carbon nanotubes (SWNTs)/L-phenylalanine (Phe) solution. The oxidized SWNTs (OSWNT) were used in this work. The scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), Raman spectrometer, Fourier transform-infrared resonance (FT-IR), Ultraviolet-visible (UV-vis) spectroscopy, Thermogravimetric analysis (TGA) and High performance liquid chromatography (HPLC) were joined together to investigate the interaction between OSWNT and Phe. The OSWNT became soluble in the water and formed a stable solution since the Phe was adsorbed. The absorbed amount of Phe on the OSWNT is around 33 wt%. Adsorption of the Phe was mainly carried out on the OSWNT with smaller diameters. The Phe molecules were absorbed on the OSWNT by conjunct interaction of the pi-pi stacking, hydrogen bond and part of covalent bond.

46 CFR 28.315 - Fire pumps, fire mains, fire hydrants, and fire hoses.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Fire pumps, fire mains, fire hydrants, and fire hoses... After September 15, 1991, and That Operate With More Than 16 Individuals on Board § 28.315 Fire pumps, fire mains, fire hydrants, and fire hoses. (a) Each vessel 36 feet (11.8 meters) or more in length must...

Bioaccumulation and Toxicity of Single-Walled Carbon Nanotubes to Benthic Organisms at the Base of the Marine Food Chain

Science.gov (United States)

As the use of single-walled carbon nanotubes (SWNTs) increases over time, so does the potential for environmental release. This research aimed to determine the toxicity, bioavailability, and bioaccumulation of SWNTs in marine benthic organisms at the base of the food chain. The t...

Growth of vertically aligned single-walled carbon nanotubes with metallic chirality through faceted FePt-Au catalysts

Science.gov (United States)

Ohashi, Toshiyuki; Iwama, Hiroki; Shima, Toshiyuki

2016-02-01

Direct synthesis of vertically aligned metallic single-walled carbon nanotubes (m-SWCNT forests) is a difficult challenge. We have successfully synthesized m-SWCNT forests using faceted iron platinum-gold catalysts epitaxially grown on a single crystalline magnesium oxide substrate. The metallic content of the forests estimated by Raman spectroscopy reaches 90%. From the standpoint of growth rate of the forests, the growth mechanism is probably based on the catalyst of solid state. It is suggested that preferential growth of m-SWCNTs is achieved when both factors are satisfied, namely, {111} dominant octahedral facet and ideal size (fine particles) of FePt particles.

Transparent and flexible supercapacitors with single walled carbon nanotube thin film electrodes.

Science.gov (United States)

Yuksel, Recep; Sarioba, Zeynep; Cirpan, Ali; Hiralal, Pritesh; Unalan, Husnu Emrah

2014-09-10

We describe a simple process for the fabrication of transparent and flexible, solid-state supercapacitors. Symmetric electrodes made up of binder-free single walled carbon nanotube (SWCNT) thin films were deposited onto polydimethylsiloxane substrates by vacuum filtration followed by a stamping method, and solid-state supercapacitor devices were assembled using a gel electrolyte. An optical transmittance of 82% was found for 0.02 mg of SWCNTs, and a specific capacitance of 22.2 F/g was obtained. The power density can reach to 41.5 kW · kg(-1) and shows good capacity retention (94%) upon cycling over 500 times. Fabricated supercapacitors will be relevant for the realization of transparent and flexible devices with energy storage capabilities, displays and touch screens in particular.

Interaction of molecular oxygen with single wall nanotubes: Role of surfactant contamination

International Nuclear Information System (INIS)

Larciprete, R.; Goldoni, A.; Lizzit, S.

2003-01-01

The interaction of molecular oxygen with single wall nanotubes in the form of a commercial bucky paper was investigated by high resolution photoemission spectroscopy. Sodium contamination was found in the sample, which was completely removed only after prolonged heating at 1250 K. The C 1s core level spectrum measured on the sample annealed to 1020 K dramatically changed upon exposure to molecular oxygen. On the contrary, when exposing the Na-free SWNTs to several KL of O 2 , the sample remained oxygen free and no modification in the C 1s core level was observed. Therefore the observed sensitivity of the sample to O 2 was due to a Na mediated oxidation, determining a charge transfer from the C tubes to the Na-O complex

Seasonality of fire weather strongly influences fire regimes in South Florida savanna-grassland landscapes.

Directory of Open Access Journals (Sweden)

William J Platt

Full Text Available Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature. We used nonparametric cluster analyses of a 17-year (1993-2009 data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires over a 13-year period with fire records (1997-2009. Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with

Seasonality of Fire Weather Strongly Influences Fire Regimes in South Florida Savanna-Grassland Landscapes

Science.gov (United States)

Platt, William J.; Orzell, Steve L.; Slocum, Matthew G.

2015-01-01

Fire seasonality, an important characteristic of fire regimes, commonly is delineated using seasons based on single weather variables (rainfall or temperature). We used nonparametric cluster analyses of a 17-year (1993–2009) data set of weather variables that influence likelihoods and spread of fires (relative humidity, air temperature, solar radiation, wind speed, soil moisture) to explore seasonality of fire in pine savanna-grassland landscapes at the Avon Park Air Force Range in southern Florida. A four-variable, three-season model explained more variation within fire weather variables than models with more seasons. The three-season model also delineated intra-annual timing of fire more accurately than a conventional rainfall-based two-season model. Two seasons coincided roughly with dry and wet seasons based on rainfall. The third season, which we labeled the fire season, occurred between dry and wet seasons and was characterized by fire-promoting conditions present annually: drought, intense solar radiation, low humidity, and warm air temperatures. Fine fuels consisting of variable combinations of pyrogenic pine needles, abundant C4 grasses, and flammable shrubs, coupled with low soil moisture, and lightning ignitions early in the fire season facilitate natural landscape-scale wildfires that burn uplands and across wetlands. We related our three season model to fires with different ignition sources (lightning, military missions, and prescribed fires) over a 13-year period with fire records (1997–2009). Largest wildfires originate from lightning and military ignitions that occur within the early fire season substantially prior to the peak of lightning strikes in the wet season. Prescribed ignitions, in contrast, largely occur outside the fire season. Our delineation of a pronounced fire season provides insight into the extent to which different human-derived fire regimes mimic lightning fire regimes. Delineation of a fire season associated with timing of

Connection Temperatures during the Mokrsko Fire Test

Directory of Open Access Journals (Sweden)

J. Chlouba

2009-01-01

Full Text Available The Mokrsko fire test focused on the overall behaviour of the structure, which cannot be observed on the separate elements, and also on the temperature of connections with improved fire resistance. During the test, measurements were made of the temperature of the gas and of the elements, the overall and relative deformations, gas pressure, humidity, the radiation of the compartment to structural element and the external steel column, transport of the moisture through the walls, and also the climatic conditions. The results of the test show the differences between the behaviour of the element and the behaviour of the structure exposed to high temperatures during a fire. The collapse of the composite slab was reached. The results of the numerical simulations using the SAFIR program compared well with the measured temperature values in the structure and also in the connections. 

Transparent and conductive polyethylene oxide film by the introduction of individualized single-walled carbon nanotubes.

Science.gov (United States)

Jung, Yong Chae; Muramatsu, Hiroyuki; Park, Ki Chul; Shimamoto, Daisuke; Kim, Jin Hee; Hayashi, Takuya; Song, Sung Moo; Kim, Yoong Ahm; Endo, Morinobu; Dresselhaus, Mildred S

2009-12-16

It is demonstrated that an optically transparent and electrically conductive polyethylene oxide (PEO) film is fabricated by the introduction of individualized single-walled carbon nanotubes (SWNTs). The incorporated SWNTs in the PEO film sustain their intrinsic electronic and optical properties and, in addition, the intrinsic properties of the polymer matrix are retained. The individualized SWNTs with smaller diameter provide high transmittance as well as good electrical conductivity in PEO films. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of CFD Modeling to Room Fire Growth on Walls

Science.gov (United States)

2003-04-01

to each particle. For fires of other geometries, expressions must be available for representing the characteristic velocity and flame length , in the...burning time, z , is the flame length , ri,, is the selected particle rate. The velocity of the particles generally depends on their launch site. But if...over the characteristic flame length , We used R* = 0.05 or 20 cells over the characteristic flame length . In FDS 2.0 the stoichiometric mixture

Chirality Characterization of Dispersed Single Wall Carbon Nanotubes

Science.gov (United States)

Namkung, Min; Williams, Phillip A.; Mayweather, Candis D.; Wincheski, Buzz; Park, Cheol; Namkung, Juock S.

2005-01-01

Raman scattering and optical absorption spectroscopy are used for the chirality characterization of HiPco single wall carbon nanotubes (SWNTs) dispersed in aqueous solution with the surfactant sodium dodecylbenzene sulfonate. Radial breathing mode (RBM) Raman peaks for semiconducting and metallic SWNTs are identified by directly comparing the Raman spectra with the Kataura plot. The SWNT diameters are calculated from these resonant peak positions. Next, a list of (n, m) pairs, yielding the SWNT diameters within a few percent of that obtained from each resonant peak position, is established. The interband transition energies for the list of SWNT (n, m) pairs are calculated based on the tight binding energy expression for each list of the (n, m) pairs, and the pairs yielding the closest values to the corresponding experimental optical absorption peaks are selected. The results reveal that (1, 11), (4, 11), and (0, 11) as the most probable chiralities of the semiconducting nanotubes. The results also reveal that (4, 16), (6, 12) and (8, 8) are the most probable chiralities for the metallic nanotubes. Directly relating the Raman scattering data to the optical absorption spectra, the present method is considered the simplest technique currently available. Another advantage of this technique is the use of the E(sup 8)(sub 11) peaks in the optical absorption spectrum in the analysis to enhance the accuracy in the results.

Electrochemical properties of double wall carbon nanotube electrodes

OpenAIRE

Pumera, Martin

2007-01-01

AbstractElectrochemical properties of double wall carbon nanotubes (DWNT) were assessed and compared to their single wall (SWNT) counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly funct...

Fire severity classification: Uses and abuses

Science.gov (United States)

Theresa B. Jain; Russell T. Graham

2003-01-01

Burn severity (also referred to as fire severity) is not a single definition, but rather a concept and its classification is a function of the measured units unique to the system of interest. The systems include: flora and fauna, soil microbiology and hydrologic processes, atmospheric inputs, fire management, and society. Depending on the particular system of interest...

Counter-ions at single charged wall: Sum rules.

Science.gov (United States)

Samaj, Ladislav

2013-09-01

For inhomogeneous classical Coulomb fluids in thermal equilibrium, like the jellium or the two-component Coulomb gas, there exists a variety of exact sum rules which relate the particle one-body and two-body densities. The necessary condition for these sum rules is that the Coulomb fluid possesses good screening properties, i.e. the particle correlation functions or the averaged charge inhomogeneity, say close to a wall, exhibit a short-range (usually exponential) decay. In this work, we study equilibrium statistical mechanics of an electric double layer with counter-ions only, i.e. a globally neutral system of equally charged point-like particles in the vicinity of a plain hard wall carrying a fixed uniform surface charge density of opposite sign. At large distances from the wall, the one-body and two-body counter-ion densities go to zero slowly according to the inverse-power law. In spite of the absence of screening, all known sum rules are shown to hold for two exactly solvable cases of the present system: in the weak-coupling Poisson-Boltzmann limit (in any spatial dimension larger than one) and at a special free-fermion coupling constant in two dimensions. This fact indicates an extended validity of the sum rules and provides a consistency check for reasonable theoretical approaches.

Quantifying Fire Impact on Alaskan Tundra from Satellite Observations and Field Measurements

Science.gov (United States)

Loboda, T. V.; Chen, D.; He, J.; Jenkins, L. K.

2017-12-01

Wildfire is a major disturbance agent in Alaskan tundra. The frequency and extent of fire events obtained from paleo, management, and satellite records may yet underestimate the scope of tundra fire impact. Field measurements, collected within the NASA's ABoVE campaign, revealed unexpectedly shallow organic soils ( 15 cm) across all sampled sites of the Noatak valley with no significant difference between recently burned and unburned sites. In typical small and medium-sized tundra burns vegetation recovers rapidly and scars are not discernable in 30 m optical satellite imagery by the end of the first post-fire season. However, field observations indicate that vegetation and subsurface characteristics within fire scars of different ages vary across the landscape. In this study we develop linkages between fire-induced changes to tundra and satellite-based observations from optical, thermal, and microwave imagers to enable extrapolation of in-situ observations to cover the full extent of Alaskan tundra. Our results show that recent ( 30 years) fire history can be reconstructed from optical observations (R2 0.65, pfire history can be determined for 4 years post fire primarily due to increased soil moisture at burned sites. Field measurements suggest that the relatively quick SAR signal dissipation results from more even distribution of surface moisture through the soil column with increases in Active Layer Thickness (ALT). Similar to previous long-term field studies we find an increase in shrub fraction and shrub height within burns over time at the landscape scale; however, the strength and significance of the relationship between shrub fraction and time since fire is governed by burn severity with more severe burns predictably (p post-fire shrub cover. Although reasonably well-correlated to each other when adjusted for topography (R2 0.35, p < 0.001), neither ALT nor soil temperature can be directly linked to optical or thermal brightness observations with acceptable

The vulcain N expert fire system

International Nuclear Information System (INIS)

Roche, A.

1989-03-01

The Institute for Nuclear Safety and Protection (IPSN) has begun work on an expert system to aid in the diagnosis of fire hazards in nuclear installations. This system is called Vulcain N and is designed as a support tool for the analyses carried out by the IPSN. Vulcain N, is based on the Vulcain expert system already developed by Bertin for its own needs and incorporates the specific rules and know-how of the IPSN experts. The development of Vulcain N began in October 1986 with the drawing up of the technical specifications, and should be completed by the end of 1988. Vulcain N brings together knowledge from a number of different domains: the locations of the combustible materials, the thermal characteristics of the combustible materials and of the walls of the room, the ventilation conditions and, finally, knowledge of fire experts concerning the development of fire. The latter covers four levels of expert knowledge: standards and their associated calculations, the simplified physics of the fire enabling more precise values to be obtained for the figures given by the standards, the rules and knowledge which enables a certain number of deductions to be made concerning the development of the fire, and a numerical simulation code which can be used to monitor the variation of certain characteristic parameters with time. For a given fire out-break scenario, Vulcain N performs diagnosis of different aspects: development of fire, effect of ventilation, emergency action possibilities, propagation hazards, etc. Owing to its flexibility, it can be used in the analysis of fire hazards to simulate a number of possible scenarios and to very rapidly deduce the essential, predominant factors. It will also be used to assist in drafting emergency procedures for application in facilities with nuclear hazards

Defects in Individual Semiconducting Single Wall Carbon Nanotubes: Raman Spectroscopic and in Situ Raman Spectroelectrochemical Study

Czech Academy of Sciences Publication Activity Database

Kalbáč, Martin; Hsieh, Y. P.; Farhat, H.; Kavan, Ladislav; Hofmann, M.; Kong, J.; Dresselhaus, M. S.

2010-01-01

Roč. 10, č. 11 (2010), s. 4619-4626 ISSN 1530-6984 R&D Projects: GA ČR GC203/07/J067; GA AV ČR IAA400400804; GA AV ČR IAA400400911; GA AV ČR KAN200100801; GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : single wall carbon nanotubes * Raman spectroscopy * defects Subject RIV: CG - Electrochemistry Impact factor: 12.186, year: 2010

Electrocatalytic oxidative determination of reserpine at electrochemically functionalized single walled carbon nanotube with polyaniline

International Nuclear Information System (INIS)

Dar, Riyaz Ahmad; Naikoo, Gowhar Ahmad; Pitre, Krishna Sadashive

2013-01-01

Graphical abstract: Electrode oxidation mechanism of reserpine at PANI modified-SWCNT/CPE. -- Highlights: • Electropolymerization of polyaniline at SWCNT/CPE. • CV, EIS, CC SEM techniques were used for characterization of electrode. • Electrode showed electrocatalytic activity towards anodic oxidation of reserpine. • Oxidation process as irreversible and adsorption-controlled. • Reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations. -- Abstract: In the present work a polyaniline film was successfully deposited by electropolymerization on single walled carbon nanotube paste electrode. The electrode was characterized using cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and scanning electron microscopy. The modified electrode showed electrocatalytic behaviour towards the anodic oxidation of reserpine. The adsorptive stripping voltammetric behaviour of reserpine at polyaniline film modified single walled carbon nanotube paste electrode (modified-SWCNTPE) was investigated and validated in pharmaceuticals and biological fluids by cyclic voltammetry (CV) and adsorptive stripping differential pulse voltammetry (AdSDPV) in 0.02 M phosphate buffer in the pH range of 2.5–8.5. Cyclic voltammetry has shown that the oxidation process is irreversible over the pH range studied and exhibited an adsorption-controlled behaviour. Further, the overall electrode process is mainly diffusion controlled with adsorption effects. The proposed more sensitive AdSDPV method allow quantitation over the range 0.085 μg mL −1 to 0.87 μg mL −1 with the detection limit of 0.407 ng mL −1 and has been successfully used to determine reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations

On the Wrapping of Polyglycolide, Poly(Ethylene Oxide), and Polyketone Polymer Chains Around Single-Walled Carbon Nanotubes Using Molecular Dynamics Simulations

Science.gov (United States)

Rouhi, S.; Alizadeh, Y.; Ansari, R.

2015-02-01

By using molecular dynamics simulations, the interaction between a single-walled carbon nanotube and three different polymers has been studied in this work. The effects of various parameters such as the nanotube geometry and temperature on the interaction energy and radius of gyration of polymers have been explored. By studying the snapshots of polymers along the single-walled carbon nanotube, it has been shown that 50 ps can be considered as a suitable time after which the shape of polymer chains around the nanotube remains almost unchanged. It is revealed that the effect of temperature on the interaction energy and radius of gyration of polymers in the range of 250 to 500 K is not significant Also, it is shown that the interaction energy depends on the nanotube diameter.

Regeneration of near-wall turbulence structures

Science.gov (United States)

Hamilton, James M.; Kim, John J.; Waleffe, Fabian A.

1993-01-01

An examination of the regeneration mechanisms of near-wall turbulence and an attempt to investigate the critical Reynolds number conjecture of Waleffe & Kim is presented. The basis is an extension of the 'minimal channel' approach of Jimenez and Moin which emphasizes the near-wall region and further reduces the complexity of the turbulent flow. Reduction of the flow Reynolds number to the minimum value which will allow turbulence to be sustained has the effect of reducing the ratio of the largest scales to the smallest scales or, equivalently, of causing the near-wall region to fill more of the area between the channel walls. In addition, since each wall may have an active near-wall region, half of the channel is always somewhat redundant. If a plane Couette flow is instead chosen as the base flow, this redundancy is eliminated: the mean shear of a plane Couette flow has a single sign, and at low Reynolds numbers, the two wall regions share a single set of structures. A minimal flow with these modifications possesses, by construction, the strongest constraints which allow sustained turbulence, producing a greatly simplified flow in which the regeneration process can be examined.

Chirality-Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and Scalable Production

Science.gov (United States)

2016-09-15

AFRL-AFOSR-VA-TR-2016-0319 Chirality -Controlled Growth of Single-Wall Carbon Nanotubes Using Vapor Phase Epitaxy: Mechanistic Understanding and...TELEPHONE NUMBER (Include area code) DISTRIBUTION A: Distribution approved for public release. 15-06-2016 final Jun 2014 - Jun 2016 Chirality ...for Public Release; Distribution is Unlimited. In this report, we present our efforts in establishing a novel and effective approach for chirality

Diameter-Sensitive Breakdown of Single-Walled Carbon Nanotubes upon KOH Activation.

Science.gov (United States)

Ye, Jianglin; Wu, Shuilin; Ni, Kun; Tan, Ziqi; Xu, Jin; Tao, Zhuchen; Zhu, Yanwu

2017-07-19

While potassium hydroxide (KOH) activation has been used to create pores in carbon nanotubes (CNTs) for improved energy-storage performance, the KOH activation mechanism of CNTs has been rarely investigated. In this work, the reaction between single-walled CNTs (SWCNTs) and KOH is studied in situ by thermogravimetric analysis coupled to infrared (IR) spectroscopy and gas chromatography/mass spectrometry (MS). The IR and MS results clearly demonstrate the sequential evolution of CO, hydrocarbons, CO 2 , and H 2 O in the activation process. By using the radial breathing mode of Raman spectroscopy, a diameter-sensitive selectivity is observed in the reaction between SWCNTs and KOH, leading to a preferential distribution of SWCNTs with diameters larger than 1 nm after activation at 900 °C and a preferential removal of SWCNTs with diameters below 1 nm upon activation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Functionalized single walled carbon nanotubes as template for water storage device

Energy Technology Data Exchange (ETDEWEB)

Paul, Sanjib; Taraphder, Srabani, E-mail: srabani@chem.iitkgp.ernet.in

2016-11-10

Single walled carbon nanotubes, endohedrally functionalized with a protonated/unprotonated carboxylic acid group, are examined as potential templates for water storage using classical molecular dynamics simulation studies. Following a spontaneous entry of water molecules into the core of model functionalized carbon nanotubes (FCNTs), a large fraction of water molecules are found to be trapped inside FCNTs of lengths 50 and 100 Å. Only water molecules near the two open ends of the nanotube are exchanged with the bulk solvent. The residence times of water molecules inside FCNTs are investigated by varying the length of the tube, the length of suspended functional group and the protonation state of the carboxylic acid group. Favorable energetic interactions between the functional group and water, assisted by a substantial gain in rotational entropy, are found to compensate for the entropy loss resulting from restricted translational diffusion of trapped water molecules.

High-performance photoresponse from single-walled carbon nanotube-zinc oxide heterojunctions

International Nuclear Information System (INIS)

Chang, Jingbo; Najeeb, Choolakadavil Khalid; Lee, Jae-Hyeok; Lee, Minsu; Kim, Jae-Ho

2011-01-01

Photoactive materials consisting of single-walled carbon nanotube (SWNT)-zinc oxide (ZnO) heterojunctions targeted for optoelectronic applications are investigated in terms of photoresponse and photovoltaic effects. The devices based on SWNT-ZnO heterojunction films are fabricated by two step processes: first, a well aligned SWNT monolayer is deposited on an oxide substrate by the Langmuir-Blodgett (LB) technique; then a ZnO film prepared by filtration of ZnO nanowire solution is transferred onto the SWNT film to form SWNT-ZnO junctions. The SWNT-ZnO heterojunction demonstrates faster photoresponse time (2.75 s) up to 18 times and photovoltaic efficiency (1.33 nA) up to 4 times higher than that of only a ZnO device. Furthermore, the mechanisms of UV sensitivity enhancement and photovoltaic effects are explained according to the high electron mobility in the SWNT-ZnO heterojunctions.

Nonlinear free vibration of single walled Carbone NanoTubes conveying fluid

Directory of Open Access Journals (Sweden)

Azrar A.

2014-04-01

Full Text Available Nonlinear free vibration of single-walled carbon nanotubes (CNTs conveying fluid are modeled and numerically simulated based on von Kármán geometric nonlinearity and Eringen’s nonlocal elasticity theory. The CNTs are modelled as nanobeams where the effects of transverse shear deformation and rotary inertia are considered within the framework of Timoshenko beam theory. The governing equations and boundary conditions are derived using the Hamilton’s principle and the nonlinear equation of motion is solved by the Galerkin’s method. The small scale parameter and the fluid-tube interaction effects on the dynamic behaviours of the CNT-fluid system as well as the instabilities induced by the fluid-velocity can be investigated. The critical fluid-velocity and frequency-amplitude relationships as well as the flutter and divergence instability types and the associated time responses are obtained based on the presented methodological approach.

Fire Intensity Data for Validation of the Radiative Transfer Equation

Energy Technology Data Exchange (ETDEWEB)

Blanchat, Thomas K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jernigan, Dann A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-01-01

A set of experiments and test data are outlined in this report that provides radiation intensity data for the validation of models for the radiative transfer equation. The experiments were performed with lightly-sooting liquid hydrocarbon fuels that yielded fully turbulent fires 2 m diameter). In addition, supplemental measurements of air flow and temperature, fuel temperature and burn rate, and flame surface emissive power, wall heat, and flame height and width provide a complete set of boundary condition data needed for validation of models used in fire simulations.

Domain wall kinetics of lithium niobate single crystals near the hexagonal corner

Energy Technology Data Exchange (ETDEWEB)

Choi, Ju Won [Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Ko, Do-Kyeong [Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Advanced Photonics Research Institute, GIST, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Yu, Nan Ei, E-mail: neyu@gist.ac.kr, E-mail: jhro@pnu.edu [Advanced Photonics Research Institute, GIST, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Kitamura, Kenji [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Ro, Jung Hoon, E-mail: neyu@gist.ac.kr, E-mail: jhro@pnu.edu [Department of Biomedical Engineering, School of Medicine, Pusan National University, Busan 602-739 (Korea, Republic of)

2015-03-09

A mesospheric approach based on a simple microscopic 2D Ising model in a hexagonal lattice plane is proposed to explain macroscopic “asymmetric in-out domain wall motion” observation in the (0001) plane of MgO-doped stoichiometric lithium niobate. Under application of an electric field that was higher than the conventional coercive field (E{sub c}) to the ferroelectric crystal, a natural hexagonal domain was obtained with walls that were parallel to the Y-axis of the crystal. When a fraction of the coercive field of around 0.1E{sub c} is applied in the reverse direction, this hexagonal domain is shrunk (moved inward) from the corner site into a shape with a corner angle of around 150° and 15° wall slopes to the Y-axis. A flipped electric field of 0.15E{sub c} is then applied to recover the natural hexagonal shape, and the 150° corner shape changes into a flat wall with 30° slope (moved outward). The differences in corner domain shapes between inward and outward domain motion were analyzed theoretically in terms of corner and wall site energies, which are described using the domain corner angle and wall slope with respect to the crystal Y-axis, respectively. In the inward domain wall motion case, the energy levels of the evolving 150° domain corner and 15° slope walls are most competitive, and could co-exist. In the outward case, the energy levels of corners with angles >180° are highly stable when compared with the possible domain walls; only a flat wall with 30° slope to the Y-axis is possible during outward motion.

Spin wave dynamics in Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes

Energy Technology Data Exchange (ETDEWEB)

Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China)

2016-09-15

The spin wave dynamics, including the magnetization, spin wave dispersion relation, and energy level splitting, of Heisenberg ferromagnetic/antiferromagnetic single-walled nanotubes are systematically calculated by use of the double-time Green’s function method within the random phase approximation. The role of temperature, diameter of the tube, and wave vector on spin wave energy spectrum and energy level splitting are carefully analyzed. There are two categories of spin wave modes, which are quantized and degenerate, and the total number of independent magnon branches is dependent on diameter of the tube, caused by the physical symmetry of nanotubes. Moreover, the number of flat spin wave modes increases with diameter of the tube rising. The spin wave energy and the energy level splitting decrease with temperature rising, and become zero as temperature reaches the critical point. At any temperature, the energy level splitting varies with wave vector, and for a larger wave vector it is smaller. When pb=π, the boundary of first Brillouin zone, spin wave energies are degenerate, and the energy level splittings are zero.

Electrical Transport and Magnetoresistance in Single-Wall Carbon Nanotubes Films

Directory of Open Access Journals (Sweden)

Vitaly KSENEVICH

2014-06-01

Full Text Available Electrical transport properties and magnetoresistance of single-wall carbon nanotubes (SWCNT films were investigated within temperature range (2 – 300 K and in magnetic fields up to 8 T. A crossover between metallic (dR/dT > 0 and non-metallic (dR/dT < 0 temperature dependence of the resistance as well as low-temperature saturation of the resistance in high bias regime indicated on the diminishing of role of the contact barriers between individual nanotubes essential for the charge transport in SWCNT arrays. The magnetoresistance (MR data demonstrated influence of weak localization and electron-electron interactions on charge transport properties in SWCNT films. The low-field negative MR with positive upturn was observed at low temperatures. At T > 10 K only negative MR was observed in the whole range of available magnetic fields. The negative MR can be approximated using 1D weak localization (WL model. The low temperature positive MR is induced by contribution from electron-electron interactions. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6311

Tight binding electronic band structure calculation of achiral boron nitride single wall nanotubes

International Nuclear Information System (INIS)

Saxena, Prapti; Sanyal, Sankar P

2006-01-01

In this paper we report the Tight-Binding method, for the electronic structure calculations of achiral single wall Boron Nitride nanotubes. We have used the contribution of π electron only to define the electronic band structure for the solid. The Zone-folding method is used for the Brillouin Zone definition. Calculation of tight binding model parameters is done by fitting them to available experimental results of two-dimensional hexagonal monolayers of Boron Nitride. It has been found that all the boron nitride nanotubes (both zigzag and armchair) are constant gap semiconductors with a band gap of 5.27eV. All zigzag BNNTs are found to be direct gap semiconductors while all armchair nanotubes are indirect gap semiconductors. (author)

Numerical prediction of heat-flux to massive calorimeters engulfed in regulatory fires with the cask analysis fire environment (CAFE) model

International Nuclear Information System (INIS)

Koski, Jorman A.; Suo-Antitla, Ahti; Kramer M, Alex; Greiner, Miles

2000-01-01

Recent observations show that the thermal boundary conditions within large-scale fires are significantly affected by the presence of thermally massive objects. These objects cool the soot and gas near their surfaces, and these effects reduce the incoming radiant heat-flux to values lower than the levels expected from simple σT fire 4 models. They also affect the flow and temperature fields in the fire far from their surfaces. The Cask Analysis Fire Environment (CAFE) code has been developed at Sandia National Laboratories to provide an enhanced fire boundary condition for the design of radioactive material packages. CAFE is a set of computer subroutines that use computational fluid mechanics methods to predict convective heat transfer and mixing. It also includes models for fuel and oxygen transport, chemical reaction, and participating-media radiation heat transfer. This code uses two-dimensional computational models so that it has reasonably short turnaround times on standard workstations and is well suited for design and risk studies. In this paper, CAFE is coupled with a commercial finite-element program to model a large cylindrical calorimeter fully engulfed in a pool fire. The time-dependent heat-flux to the calorimeter and the calorimeter surface temperature are determined for several locations around the calorimeter circumference. The variation of heat-flux with location is determined for calorimeters with different diameters and wall thickness, and the observed effects discussed

Growth mechanism and internal structure of vertically aligned single-walled carbon nanotubes.

Science.gov (United States)

Einarsson, Erik; Kadowaki, Masayuki; Ogura, Kazuaki; Okawa, Jun; Xiang, Rong; Zhang, Zhengyi; Yamamoto, Takahisa; Ikuhara, Yuichi; Maruyama, Shigeo

2008-11-01

An in situ optical absorbance technique was used to monitor the growth of vertically aligned single-walled carbon nanotubes (VA-SWNTs) at various temperatures and pressures. The effects of the growth temperature and ethanol pressure on the initial growth rate and catalyst lifetime were investigated. It was found that the ideal pressure for VA-SWNT synthesis changes with the growth temperature, shifting toward higher pressure as the growth temperature increases. It was also found that the growth reaction is first-order below this ideal pressure. Additionally, the internal structure of the VA-SWNT film was observed at different depths into the film by transmission electron microscopy. The absence of large bundles was confirmed, and little change in the structure was observed to a depth of approximately 1 microm.

The electrochemical signature of functionalized single-walled carbon nanotubes bearing electroactive groups

International Nuclear Information System (INIS)

Le Floch, Fabien; Thuaire, Aurelie; Simonato, Jean-Pierre; Bidan, Gerard

2009-01-01

We report the modification and characterization of single-walled carbon nanotubes (SWCNTs) in view of molecular sensing applications. We found that ultrasonicated SWCNTs present sticking properties that make them adhere on electrode surfaces. This allows excellent characterization of SWCNTs by cyclic voltammetry (CV) before and after chemical functionalization with diazonium salts bearing electroactive groups. Bare SWCNTs presented distinct invariant shapes in CV, used as control curves, in comparison with functionalized SWCNTs for which specific signatures corresponding to the presence of grafted molecules were identified. According to the electronic substituents in the para position of the diazonium salts, divergent behaviours were observed for the grafting reactions. Diazonium salts having electrowithdrawing groups could be grafted without electrochemical induction whereas those bearing electron donating groups required a cathodic potential to generate the formation of the radical species.

The electrochemical signature of functionalized single-walled carbon nanotubes bearing electroactive groups

Energy Technology Data Exchange (ETDEWEB)

Le Floch, Fabien; Thuaire, Aurelie; Simonato, Jean-Pierre [LITEN/DTNM/LCRE, CEA-Grenoble 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Bidan, Gerard [INAC/DIR, CEA-Grenoble 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)], E-mail: jean-pierre.simonato@cea.fr

2009-04-08

We report the modification and characterization of single-walled carbon nanotubes (SWCNTs) in view of molecular sensing applications. We found that ultrasonicated SWCNTs present sticking properties that make them adhere on electrode surfaces. This allows excellent characterization of SWCNTs by cyclic voltammetry (CV) before and after chemical functionalization with diazonium salts bearing electroactive groups. Bare SWCNTs presented distinct invariant shapes in CV, used as control curves, in comparison with functionalized SWCNTs for which specific signatures corresponding to the presence of grafted molecules were identified. According to the electronic substituents in the para position of the diazonium salts, divergent behaviours were observed for the grafting reactions. Diazonium salts having electrowithdrawing groups could be grafted without electrochemical induction whereas those bearing electron donating groups required a cathodic potential to generate the formation of the radical species.

DFT investigation of NH_3, PH_3, and AsH_3 adsorptions on Sc-, Ti-, V-, and Cr-doped single-walled carbon nanotubes

International Nuclear Information System (INIS)

Buasaeng, Prayut; Rakrai, Wandee; Wanno, Banchob; Tabtimsai, Chanukorn

2017-01-01

Highlights: • Transition metal-doped single wall carbon nanotubes and their adsorption with NH_3, PH_3 and AsH_3 molecules were investigated using a DFT method. • Adsorptions of NH_3, PH_3 and AsH_3 molecules on pristine single wall carbon nanotubeswere improved by transition metal doping. • Structural and electronic properties of single wall carbon nanotubes were significantly changed by transition metal doping and gas adsorptions. - Abstract: The adsorption properties of ammonia (NH_3), phosphine (PH_3), and arsine (AsH_3) on pristine and transition metal- (TM = Sc, Ti, V, and Cr) doped (5,5) armchair single-walled carbon nanotubes (SWCNTs) were theoretically investigated. The geometric and electronic properties and adsorption abilities for the most stable configuration of NH_3, PH_3, and AsH_3 adsorptions on pristine and TM-doped SWCNTs were calculated. It was found that the binding abilities of TMs to the SWCNT were in the order: Cr > V > Sc > Ti. However, the adsorption energy showed that the pristine SWCNT weakly adsorbed gas molecules and its electronic properties were also insensitive to gas molecules. By replacing a C atom with TM atoms, all doping can significantly enhance the adsorption energy of gas/SWCNT complexes and their adsorption ability was in the same order: NH_3 > PH_3 > AsH_3. A remarkable increase in adsorption energy and charge transfer of these systems was expected to induce significant changes in the electrical conductivity of the TM-doped SWCNTs. This work revealed that the sensitivity of SWCNT-based chemical gas adsorptions and sensors can be greatly improved by introducing an appropriate TM dopant. Accordingly, TM-doped SWCNTs are more suitable for gas molecule adsorptions and detections than the pristine SWCNT.

Fires. A Joint Publication for U.S. Artillery Professionals. September - October 2011

Science.gov (United States)

2011-01-01

fragments, raining down on the enemy. Standard cannon direct fire using glass and iron sights is basically an analog fire control system. In...that foundation with some walls, flooring and a ceiling . The Army has trained the EWOs how to employ their craft; now it needs to enable them by...Old Guards had fled the fall of Iran, blended in with the rest of the Pasdaran and Hezbollah remnants hiding in the Beka’a Valley of central Lebanon

Strengthening of Unreinforced Masonry Walls with Composite Materials

Directory of Open Access Journals (Sweden)

Ioana-Sorina Enţuc

2004-01-01

Full Text Available Unreinforced masonry (URM is considered one of the oldest construction materials being until the end of XIXth century, the basic material for: foundations, walls, columns, volts, staircases, floor joints, roofs, retaining walls, drainage channels, barrages, etc. Construction with URM elements posses a series of advantages such as: fire resistance, thermal an acoustic insulations between interior and outside spaces, humidity resistance. However the URM elements have some significant inconveniences such as: large self weight (heaviness causes cracks in the other elements of structures, reduced mechanical strengths in comparison with other traditional materials (steel and concrete, low tenacity, great manual labor consumptions, and vulnerability to earthquakes. Various factors cause deteriorations which must be overcome by strengthening solutions. Some strengthening solutions based on fiber reinforced polymers (FRP products applied directly on URM brick walls are presented in the paper.

The Impact of Sonication on the Surface Quality of Single-Walled Carbon Nanotubes.

Science.gov (United States)

Koh, Byumseok; Cheng, Wei

2015-08-01

Sonication process is regularly adopted for dispersing single-walled carbon nanotubes (SWCNTs) in an aqueous medium. This can be achieved by either covalent functionalization of SWCNTs with strong acid or by noncovalent functionalization using dispersants that adsorb onto the surface of SWCNTs during dispersion. Because the dispersion process is usually performed using sonication, unintentional free radical formation during sonication process may induce covalent modification of SWCNT surface. Herein, we have systematically investigated the status of SWCNT surface modification under various sonication conditions using Raman spectroscopy. Comparing ID /IG (Raman intensities between D and G bands) ratio of SWCNTs under various sonication conditions suggests that typical sonication conditions (1-6 h bath sonication with sonication power between 3 and 80 W) in aqueous media do not induce covalent modification of SWCNT surface. In addition, we confirm that SWCNT dispersion with single-stranded DNA (ssDNA) involves noncovalent adsorption of ssDNA onto the surface of SWCNTs, but not covalent linkage between ssDNA and SWCNT surface. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Surprising synthesis of nanodiamond from single-walled carbon nanotubes by the spark plasma sintering process

Science.gov (United States)

Mirzaei, Ali; Ham, Heon; Na, Han Gil; Kwon, Yong Jung; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo

2016-10-01

Nanodiamond (ND) was successfully synthesized using single-walled carbon nanotubes (SWCNTs) as a pure solid carbon source by means of a spark plasma sintering process. Raman spectra and X-ray diffraction patterns revealed the generation of the cubic diamond phase by means of the SPS process. Lattice-resolved TEM images confirmed that diamond nanoparticles with a diameter of about ˜10 nm existed in the products. The NDs were generated mainly through the gas-phase nucleation of carbon atoms evaporated from the SWCNTs. [Figure not available: see fulltext.

Small Scale Hydrocarbon Fire Test Concept

OpenAIRE

Joachim Søreng Bjørge; Maria-Monika Metallinou; Arjen Kraaijeveld; Torgrim Log

2017-01-01

In the oil and gas industry, hydrocarbon process equipment was previously often thermally insulated by applying insulation directly to the metal surface. Fire protective insulation was applied outside the thermal insulation. In some cases, severe corrosion attacks were observed due to ingress of humidity and condensation at cold surfaces. Introducing a 25 mm air gap to prevent wet thermal insulation and metal wall contact is expected to solve the corrosion issues. This improved insulation met...

Simultaneous Determination of Parathion, Malathion, Diazinon, and Pirimiphos Methyl in Dried Medicinal Plants Using Solid-Phase Microextraction Fibre Coated with Single-Walled Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Reza Ahmadkhaniha

2012-01-01

Full Text Available A reliable and sensitive headspace solid-phase microextraction gas chromatography-mass spectrometry method for simultaneous determination of different organophosphorus pesticides in dried medicinal plant samples is described. The analytes were extracted by single-walled carbon nanotubes as a new solid-phase microextraction adsorbent. The developed method showed good performance. For diazinon and pirimiphos methyl calibration, curves were linear (r2≥0.993 over the concentration ranges from 1.5 to 300 ng g−1, and the limit of detection at signal-to-noise ratio of 3 was 0.3 ng g−1. For parathion and malathion, the linear range and limit of detection were 2.5–300 (r2≥0.991 and 0.5 ng g−1, respectively. In addition, a comparative study between the single-walled carbon nanotubes and a commercial polydimethylsiloxane fibre for the determination of target analytes was carried out. Single-walled carbon nanotubes fibre showed higher extraction capacity, better thermal stability (over 350∘C, and longer lifespan (over 250 times than the commercial polydimethylsiloxane fibre. The developed method was successfully applied to determine target organophosphorus pesticides in real samples.

Effects of drain-wall in mitigating N-hit single event transient via 45 nm CMOS process

International Nuclear Information System (INIS)

Xu, X Y; Tang, M H; Xiao, Y G; Yan, S A; Zhang, W L; Li, Z; Xiong, Y; Zhao, W; Guo, H X

2015-01-01

A three-dimensional (3D) technology computer-aided design (TCAD) simulation in a novel layout technique for N-hit single event transient (SET) mitigation based on drain-wall layout technique is proposed. Numerical simulations of both single-device and mixed-mode show that the proposed layout technique designed with 45 nm CMOS process can efficiently reduce not only charge collection but also SET pulse widths (W SET ). What is more, simulations show that impacts caused by part of ion-incidents can be shielded with this novel layout technique. When compared with conventional layout technique and guard drain layout technique, we find that the proposed novel layout technique can provide the best benefit of SET mitigation with a small sacrifice in effective area. (paper)

Coupled Cluster Studies of Ionization Potentials and Electron Affinities of Single-Walled Carbon Nanotubes

Energy Technology Data Exchange (ETDEWEB)

Peng, Bo; Govind, Niranjan; Apra, Edoardo; Klemm, Michael; Hammond, Jeff R.; Kowalski, Karol

2017-02-03

In this paper we apply equation-of-motion coupled cluster (EOMCC) methods in studies of vertical ionization potentials (IP) and electron affinities (EA) for sin- gled walled carbon nanotubes. EOMCC formulations for ionization potentials and electron affinities employing excitation manifolds spanned by single and double ex- citations (IP/EA-EOMCCSD) are used to study IPs and EAs of nanotubes as a function of nanotube length. Several armchair nanotubes corresponding to C20nH20 models with n = 2 - 6 have been used in benchmark calculations. In agreement with previous studies, we demonstrate that the electronegativity of C20nH20 systems remains, to a large extent, independent of nanotube length. We also compare IP/EA- EOMCCSD results with those obtained with the coupled cluster models with single and double excitations corrected by perturbative triples, CCSD(T), and density func- tional theory (DFT) using global and range-separated hybrid exchange-correlation functionals.

Single walled carbon nanotube composites for bone tissue engineering.

Science.gov (United States)

Gupta, Ashim; Woods, Mia D; Illingworth, Kenneth David; Niemeier, Ryan; Schafer, Isaac; Cady, Craig; Filip, Peter; El-Amin, Saadiq F

2013-09-01

The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic-co-glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3-E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3-E1 and hBMSCs cells exhibited normal, non-stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications. Copyright © 2013 Orthopaedic Research Society.

Single-walled carbon nanotubes nanocomposite microacoustic organic vapor sensors

Energy Technology Data Exchange (ETDEWEB)

Penza, M. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy)]. E-mail: michele.penza@brindisi.enea.it; Tagliente, M.A. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Aversa, P. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Cassano, G. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy); Capodieci, L. [ENEA, Materials and New Technologies Unit, SS. 7, Appia, km 714, 72100 Brindisi (Italy)

2006-07-15

We have developed highly sensitive microacoustic vapor sensors based on surface acoustic waves (SAWs) configured as oscillators using a two-port resonator 315, 433 and 915 MHz device. A nanocomposite film of single-walled carbon nanotubes (SWCNTs) embedded in a cadmium arachidate (CdA) amphiphilic organic matrix was prepared by Langmuir-Blodgett technique with a different SWCNTs weight filler content onto SAW transducers as nanosensing interface for vapor detection, at room temperature. The structural properties and surface morphology of the nanocomposite have been examined by X-ray diffraction, transmission and scanning electron microscopy, respectively. The sensing properties of SWCNTs nanocomposite LB films consisting of tangled nanotubules have been also investigated by using Quartz Crystal Microbalance 10 MHz AT-cut quartz resonators. The measured acoustic sensing characteristics indicate that the room-temperature SAW sensitivity to polar and nonpolar tested organic molecules (ethanol, ethylacetate, toluene) of the SWCNTs-in-CdA nanocomposite increases with the filler content of SWCNTs incorporated in the nanocomposite; also the SWCNTs-in-CdA nanocomposite vapor sensitivity results significantly enhanced with respect to traditional organic molecular cavities materials with a linearity in the frequency change response for a given nanocomposite weight composition and a very low sub-ppm limit of detection.

Purity Evaluation of Bulk Single Wall Carbon Nanotube Materials

International Nuclear Information System (INIS)

Dettlaff-Weglikowska, U.; Hornbostel, B.; Cech, J.; Roth, S.; Wang, J.; Liang, J.

2005-01-01

We report on our experience using a preliminary protocol for quality control of bulk single wall carbon nanotube (SWNT) materials produced by the electric arc-discharge and laser ablation method. The first step in the characterization of the bulk material is mechanical homogenization. Quantitative evaluation of purity has been performed using a previously reported procedure based on solution phase near-infrared spectroscopy. Our results confirm that this method is reliable in determining the nanotube content in the arc-discharge sample containing carbonaceous impurities (amorphous carbon and graphitic particles). However, the application of this method to laser ablation samples gives a relative purity value over 100 %. The possible reason for that might be different extinction coefficient meaning different oscillator strength of the laser ablation tubes. At the present time, a 100 % pure reference sample of laser ablation SWNT is not available, so we chose to adopt the sample showing the highest purity as a new reference sample for a quantitative purity evaluation of laser ablation materials. The graphitic part of the carbonaceous impurities has been estimated using X-ray diffraction of 1:1 mixture of nanotube material and C60 as an internal reference. To evaluate the metallic impurities in the as prepared and homogenized carbon nanotube soot inductive coupled plasma (ICP) has been used

Antimicrobial Activity of Single-Walled Carbon Nanotubes Suspended in Different Surfactants

Directory of Open Access Journals (Sweden)

Lifeng Dong

2012-01-01

Full Text Available We investigated the antibacterial activity of single-walled carbon nanotubes (SWCNTs dispersed in surfactant solutions of sodium cholate, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfate. Among the three surfactants, sodium cholate demonstrated the weakest antibacterial activity against Salmonella enterica, Escherichia coli, and Enterococcus faecium and thereby was used to disperse bundled SWCNTs in order to study nanotube antibiotic activity. SWCNTs exhibited antibacterial characteristics for both S. enterica and E. coli. With the increase of nanotube concentrations from 0.3 mg/mL to 1.5 mg/mL, the growth curves had plateaus at lower absorbance values whereas the absorbance value was not obviously affected by the incubation ranging from 5 min to 2 h. Our findings indicate that carbon nanotubes could become an effective alternative to antibiotics in dealing with drug-resistant and multidrug-resistant bacterial strains because of the physical mode of bactericidal action that SWCNTs display.

Transverse electric field–induced deformation of armchair single-walled carbon nanotube

Directory of Open Access Journals (Sweden)

Yuan Ningyi

2010-01-01

Full Text Available Abstract The deformation of armchair single-walled carbon nanotube under transverse electric field has been investigated using density functional theory. The results show that the circular cross-sections of the nanotubes are deformed to elliptic ones, in which the tube diameter along the field direction is increased, whereas the diameter perpendicular to the field direction is reduced. The electronic structures of the deformed nanotubes were also studied. The ratio of the major diameter to the minor diameter of the elliptic cross-section was used to estimate the degree of the deformation. It is found that this ratio depends on the field strength and the tube diameter. However, the field direction has little role in the deformation. (See supplementary material 1 Electronic supplementary material The online version of this article (doi:10.1007/s11671-010-9617-y contains supplementary material, which is available to authorized users. Click here for file

Flux mapping at 77 K and local measurement at lower temperature of thin-wall YBaCuO single-domain samples oxygenated under high pressure

Energy Technology Data Exchange (ETDEWEB)

Chaud, X., E-mail: Xavier.chaud@grenoble.cnrs.f [CRETA, CNRS, 25, Avenue des Martyrs, 38042 Grenoble Cedex 9 (France); Noudem, J. [CRISMAT/ENSICAEN, CNRS, 6 bd Marechal Juin, 14050 Caen (France); Prikhna, T.; Savchuk, Y. [ISM, National Acad. of Sciences of Ukraine, 2 Avtozavodskaya Street, Kiev, 04074 (Ukraine); Haanappel, E. [LNCMP, UMR 5147, 143 avenue de Rangueil, 31400 Toulouse (France); Diko, P. [IEP, Slovak Acad. of Sciences, Watsonova 47, 043 53, Kosice (Slovakia); Zhang, C.P. [SMRC, NIN, 96 Weiyang Road, Xi' an 710016 (China)

2009-10-15

YBCO single-domain samples are suitable for the production of high trapped fields in the range 20-77 K using a cryocooler or liquid nitrogen. But the oxygenation process required to actually transform the single domains into superconductors induces an extensive crack network that is limiting the material performances. Thin-wall geometry has been introduced to reduce the diffusion paths and to enable a progressive oxygenation strategy. As a consequence cracks are drastically reduced. In addition the use of a high oxygen pressure (16 MPa) speeds up further the process by displacing the oxygen-temperature equilibrium towards the higher temperature of the phase diagram. The advantage of thin-wall geometry is that such an annealing can be applied directly to a much larger sample. Remarkable results are obtained without any doping by the combination of thin walls and oxygen high pressure. While classical plain samples yield 300-400 mT, a trapped field of 840 mT has been measured at 77 K on a 16 mm diameter Y123 thin-wall single-domain sample with an annealing time as short as 3 days. Local measurements with a fixed Hall probe on top of the sample were performed at lower temperature after magnetization either in a static field or in a pulse field. The trapped field is significantly higher at lower temperature. Cryocoolers become the key to compromise between performances and cryogenic cost around 40 K.

Harnessing light energy with a planar transparent hybrid of graphene/single wall carbon nanotube/n-type silicon heterojunction solar cell

DEFF Research Database (Denmark)

Chen, Leifeng; Yu, Hua; Zhong, Jiasong

2015-01-01

The photovoltaic conversion efficiency of a solar cell fabricated by a simple electrophoretic method with a planar transparent hybrid of graphenes (GPs) and single wall carbon nanotubes (SCNTs)/n-type silicon heterojunction was significantly increased compared to GPs/n-Si and SCNTs/n-Si solar cells...

The Wall On Gladstone Avenue

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Pina MARCHESE

2012-12-01

Full Text Available "Since the house is on fire, Let us warm ourselves..." (Calabrian Proverb It all began in the village. We would wake up with the sun, we would rest our laboured bodies underneath the moon. Gli vecchi (old folks often told us: "In the end, all that will remain is our story. Nothing else really matters." This article "The Wall On Gladstone Avenue" will take you into a life of duality and how immigrants "press-on" to acquire knowledge and manifest meaning in a new land Canada.

Numerical Study of Single Bubble Growth on and Departure from a Horizontal Superheated Wall by Three-dimensional Lattice Boltzmann Method

Science.gov (United States)

Feng, Yuan; Li, Hui-Xiong; Guo, Kai-Kai; Zhao, Jian-Fu; Wang, Tai

2018-05-01

A three-dimensional hybrid lattice Boltzmann method was used to simulate the progress of a single bubble's growth and departure from a horizontal superheated wall. The evolutionary process of the bubble shapes and also the temperature fields during pool nucleate boiling were obtained and the influence of the gravitational acceleration on the bubble departure diameter (BDD), the bubble release frequency (BRF) and the heat flux on the superheated wall was analyzed. The simulation results obtained by the present three-dimensional numerical studies demonstrate that the BDD is proportional to g^{-0.301}, the BRF is proportional to g^{-0.58}, and the averaged wall heat flux is proportional to g^{0.201}, where g is the gravitational acceleration. These results are in good agreement with the common-used experimental correlations, indicating the rationality of the present numerical model and results.

Temporary fire sealing of penetrations on TFTR

International Nuclear Information System (INIS)

Hondorp, H.L.

1981-02-01

The radiation shielding provided for TFTR for D-D and D-T operation will be penetrated by numerous electrical and mechanical services. Eventually, these penetrations will have to be sealed to provide the required fire resistance, tritium sealability, pressure integrity and radiation attenuation. For the initial hydrogen operation, however, fire sealing of the penetrations in the walls and floor is the primary concern. This report provides a discussion of the required and desirable properties of a temporary seal which can be used to seal these penetrations for the hydrogen operation and then subsequently be removed and replaced as required for the D-D and D-T operations. Several candidate designs are discussed and evaluated and recommendations are made for specific applications

Optical Detection of Paraoxon Using Single-Walled Carbon Nanotube Films with Attached Organophosphorus Hydrolase-Expressed Escherichia coli

Directory of Open Access Journals (Sweden)

Intae Kim

2015-05-01

Full Text Available In whole-cell based biosensors, spectrophotometry is one of the most commonly used methods for detecting organophosphates due to its simplicity and reliability. The sensor performance is directly affected by the cell immobilization method because it determines the amount of cells, the mass transfer rate, and the stability. In this study, we demonstrated that our previously-reported microbe immobilization method, a microbe-attached single-walled carbon nanotube film, can be applied to whole-cell-based organophosphate sensors. This method has many advantages over other whole-cell organophosphate sensors, including high specific activity, quick cell immobilization, and excellent stability. A device with circular electrodes was fabricated for an enlarged cell-immobilization area. Escherichia coli expressing organophosphorus hydrolase in the periplasmic space and single-walled carbon nanotubes were attached to the device by our method. Paraoxon was hydrolyzed using this device, and detected by measuring the concentration of the enzymatic reaction product, p-nitrophenol. The specific activity of our device was calculated, and was shown to be over 2.5 times that reported previously for other whole-cell organophosphate sensors. Thus, this method for generation of whole-cell-based OP biosensors might be optimal, as it overcomes many of the caveats that prevent the widespread use of other such devices.

Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF6 electrolyte

International Nuclear Information System (INIS)

Azam, M.A.; Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A.; Kudin, T.I.T.; Yahya, M.Z.A.

2015-01-01

Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF 6 non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g −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 −1 at a scan rate of 1 mV s −1

Chiral-Selective Growth of Single-Walled Carbon Nanotubes on Lattice-Mismatched Epitaxial Cobalt Nanoparticles

DEFF Research Database (Denmark)

He, Maoshuai; Jiang, Hua; Liu, Bilu

2013-01-01

Controlling chirality in growth of single-walled carbon nanotubes (SWNTs) is important for exploiting their practical applications. For long it has been conceptually conceived that the structural control of SWNTs is potentially achievable by fabricating nanoparticle catalysts with proper structures......-resolution environmental transmission electron microscope at a low CO pressure was recorded. We achieved highly preferential growth of semiconducting SWNTs (~90%) with an exceptionally large population of (6, 5) tubes (53%) in an ambient CO atmosphere. Particularly, we also demonstrated high enrichment in (7, 6) and (9, 4......) at a low growth temperature. These findings open new perspectives both for structural control of SWNTs and for elucidating the growth mechanisms....

Understorey fire frequency and the fate of burned forests in southern Amazonia.

Science.gov (United States)

Morton, D C; Le Page, Y; DeFries, R; Collatz, G J; Hurtt, G C

2013-06-05

Recent drought events underscore the vulnerability of Amazon forests to understorey fires. The long-term impact of fires on biodiversity and forest carbon stocks depends on the frequency of fire damages and deforestation rates of burned forests. Here, we characterized the spatial and temporal dynamics of understorey fires (1999-2010) and deforestation (2001-2010) in southern Amazonia using new satellite-based estimates of annual fire activity (greater than 50 ha) and deforestation (greater than 10 ha). Understorey forest fires burned more than 85 500 km(2) between 1999 and 2010 (2.8% of all forests). Forests that burned more than once accounted for 16 per cent of all understorey fires. Repeated fire activity was concentrated in Mato Grosso and eastern Pará, whereas single fires were widespread across the arc of deforestation. Routine fire activity in Mato Grosso coincided with annual periods of low night-time relative humidity, suggesting a strong climate control on both single and repeated fires. Understorey fires occurred in regions with active deforestation, yet the interannual variability of fire and deforestation were uncorrelated, and only 2.6 per cent of forests that burned between 1999 and 2008 were deforested for agricultural use by 2010. Evidence from the past decade suggests that future projections of frontier landscapes in Amazonia should separately consider economic drivers to project future deforestation and climate to project fire risk.

Mo-Co catalyst nanoparticles: Comparative study between TiN and Si surfaces for single-walled carbon nanotube growth

Energy Technology Data Exchange (ETDEWEB)

Morant, C., E-mail: c.morant@uam.es [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Campo, T. [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Marquez, F. [School of Science and Technology, University of Turabo, 00778-PR (United States); Domingo, C. [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain); Sanz, J.M.; Elizalde, E. [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain)

2012-06-01

Highly pure single-walled carbon nanotubes (SWNT) were synthesized by alcohol catalytic chemical vapor deposition on silicon substrates partially covered by a thin layer of TiN. The TiN coating selectively prevented the growth of carbon nanotubes. Field emission scanning electron microscopy and Raman spectroscopy revealed the formation of high purity vertically aligned SWNT in the Si region. X-ray Photoelectron Spectroscopy and Atomic Force Microscopy indicated that Co nanoparticles are present on the Si regions, and not on the TiN regions. This clearly explains the obtained experimental results: the SWNT only grow where the Co is presented as nanoparticles, i.e. on the Si regions. - Highlights: Black-Right-Pointing-Pointer Single-wall carbon nanotubes (SWNT) ontained by catalytic chemical vapor-deposition. Black-Right-Pointing-Pointer Substrate/Co-Mo catalyst behaviour plays a key role in the SWNT growth. Black-Right-Pointing-Pointer Co nanoparticles (the effective catalyst) have been only observed on the Si region. Black-Right-Pointing-Pointer High purity SWNT were spatially confined in specific locations (Si regions). Black-Right-Pointing-Pointer TiN-coated surfaces, adjacent to a Si oxide region, prevent the growth of SWNT.

The Long-Term Fate and Toxicity of PEG-Modified Single-Walled Carbon Nanotube Isoliquiritigenin Delivery Vehicles in Rats

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Bo Han

2014-01-01

Full Text Available Oxidized single-walled carbon nanotubes (o-SWNTs was modified by covalently and noncovalently linking PEG to the o-SWNTs. The influence of oxidation time, PEG molecular weight, and type of PEG linkage on the blood clearance time of PEG-modified single-walled carbon nanotubes (SWNTs was investigated. The toxicity profile of SWNTs covalently linked to PEG (c-PEG-o-SWNTs in rats has also been determined. The pharmacokinetics of c-PEG-o-SWNTs in rats and their distribution in vital organs were monitored by Raman spectroscopy, and the blood clearance of homogenate isoliquiritigenin (ISL was determined by HPLC. Photos of tissue and tissue sections were taken to evaluate the toxicity of c-PEG-o-SWNTs. We found that SWNTs which were covalently modified with PEG and have a molecular weight of 3500 had the longest blood clearance half-lives. However, SWNTs were toxic to the kidneys and the hearts. The high renal clearance of long-term fate SWNTs may occur because of impaired kidney filtration function. Therefore, we assume that while researchers study the long-term fate of SWNTs, the toxicity of SWNTs also needs to be taken into account.

Multi-compartment Fire Modeling for Switchgear Room using CFAST

International Nuclear Information System (INIS)

Han, Kiyoon; Kang, Dae Il; Lim, Ho Gon

2015-01-01

In this study, multi-compartment fire modeling for fire propagation scenario from SWGR A to SWGR B is performed using CFAST. New fire PSA method (NUREG/CR-6850) requires that the severity factor is to be calculated by fire modeling. If fire modeling is not performed, the severity factor should be estimated as one conservatively. Also, the possibility of the damages of components and cables located at adjacent compartments should be considered. Detailed fire modeling of multi-compartment fires refers to the evaluation of fire-generated conditions in one compartment that spread to adjacent ones. In general, the severity factor for multi-compartment fire scenario is smaller than that of single compartment scenario. Preliminary quantification of Hanul Unit 3 fire PSA was performed without fire modeling. As a result of quantification, multi-compartment scenario, fire propagation scenario from switchgear room (SWGR) A to SWGR B, is one of significant contributor to the CDF. In this study, fire modeling of multi-compartment was performed by Consolidated Fire Growth and Smoke Transport (CFAST) to identify the possibility of fire propagation. As a result of fire simulation, it is identified that fire propagation has little influences

Multi-compartment Fire Modeling for Switchgear Room using CFAST

Energy Technology Data Exchange (ETDEWEB)

Han, Kiyoon; Kang, Dae Il; Lim, Ho Gon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

In this study, multi-compartment fire modeling for fire propagation scenario from SWGR A to SWGR B is performed using CFAST. New fire PSA method (NUREG/CR-6850) requires that the severity factor is to be calculated by fire modeling. If fire modeling is not performed, the severity factor should be estimated as one conservatively. Also, the possibility of the damages of components and cables located at adjacent compartments should be considered. Detailed fire modeling of multi-compartment fires refers to the evaluation of fire-generated conditions in one compartment that spread to adjacent ones. In general, the severity factor for multi-compartment fire scenario is smaller than that of single compartment scenario. Preliminary quantification of Hanul Unit 3 fire PSA was performed without fire modeling. As a result of quantification, multi-compartment scenario, fire propagation scenario from switchgear room (SWGR) A to SWGR B, is one of significant contributor to the CDF. In this study, fire modeling of multi-compartment was performed by Consolidated Fire Growth and Smoke Transport (CFAST) to identify the possibility of fire propagation. As a result of fire simulation, it is identified that fire propagation has little influences.

Selective Growth of Metallic and Semiconducting Single Walled Carbon Nanotubes on Textured Silicon.

Science.gov (United States)

Jang, Mira; Lee, Jongtaek; Park, Teahee; Lee, Junyoung; Yang, Jonghee; Yi, Whikun

2016-03-01

We fabricated the etched Si substrate having the pyramidal pattern size from 0.5 to 4.2 μm by changing the texturing process parameters, i.e., KOH concentration, etching time, and temperature. Single walled carbon nanotubes (SWNTs) were then synthesized on the etched Si substrates with different pyramidal pattern by chemical vapor deposition. We investigated the optical and electronic properties of SWNT film grown on the etched Si substrates of different morphology by using scanning electron microscopy, Raman spectroscopy and conducting probe atomic force microscopy. We confirmed that the morphology of substrate strongly affected the selective growth of the SWNT film. Semiconducting SWNTs were formed on larger pyramidal sized Si wafer with higher ratio compared with SWNTs on smaller pyramidal sized Si.

Spectroscopic study of the diameter distribution of B-doped single-walled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ruiz-Soria, G.; Pichler, T.; Ayala, P. [University of Vienna, Faculty of Physics, 1090 Vienna (Austria); Daothong, S. [Chiang Mai University, Faculty of Science, 50200 Chiang Mai (Thailand)

2012-12-15

In this paper, we report on the diameter distribution of boron-doped single-walled carbon nanotubes grown from triethyl borate with high vacuum chemical vapor deposition, using multi-frequency Raman resonance spectroscopy. The nanotube yield is higher than in previously reported material produced with the same method. Our results suggest that the amount of as-grown material and the range of diameters are directly correlated with feedstock used in the synthesis. The I{sub D}/I{sub G} ratio shows that the morphology of the samples is critically affected by the temperature. The population of diameters in the optimal conditions shows a Poisson distribution with a mean value at {proportional_to}1.15 nm. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Controlled nanostructure and high loading of single-walled carbon nanotubes reinforced polycarbonate composite

International Nuclear Information System (INIS)

Wang Shiren; Liang Zhiyong; Pham, Giang; Park, Young-Bin; Wang, Ben; Zhang, Chuck; Kramer, Leslie; Funchess, Percy

2007-01-01

This paper presents an effective technique to fabricate thermoplastic nanocomposites with high loading of well-dispersed single-walled carbon nanotubes (SWNTs). SWNT membranes were made from a multi-step dispersion and filtration method, and then impregnated with polycarbonate solution to make thermoplastic nanocomposites. High loading of nanotubes was achieved by controlling the viscosity of polycarbonate solution. SEM and AFM characterization results revealed the controlled nanostructure in the resultant nanocomposites. Dynamic mechanical property tests indicated that the storage modulus of the resulting nanocomposites at 20 wt% nanotubes loading was improved by a factor of 3.4 compared with neat polycarbonate material. These results suggest the developed approach is an effective way to fabricate thermoplastic nanocomposites with good dispersion and high SWNT loading

Modeling the differentiation of A- and C-type baroreceptor firing patterns

DEFF Research Database (Denmark)

Sturdy, Jacob; Ottesen, Johnny T.; Olufsen, Mette

2017-01-01

The baroreceptor neurons serve as the primary transducers of blood pressure for the autonomic nervous system and are thus critical in enabling the body to respond effectively to changes in blood pressure. These neurons can be separated into two types (A and C) based on the myelination...... of their axons and their distinct firing patterns elicited in response to specific pressure stimuli. This study has developed a comprehensive model of the afferent baroreceptor discharge built on physiological knowledge of arterial wall mechanics, firing rate responses to controlled pressure stimuli, and ion...

Integrated approach to fire safety at the Krsko nuclear power plant - fire protection action plan

International Nuclear Information System (INIS)

Lambright, J.A.; Cerjak, J.; Spiler, J.; Ioannidi, J.

1998-01-01

Nuclear Power Plant Krsko (NPP Krsko) is a Westinghouse design, single-unit, 1882 Megawatt thermal (MWt), two-loop, pressurized water nuclear power plant. The fire protection program at NPP Krsko has been reviewed and reports issued recommending changes and modifications to the program, plant systems and structures. Three reports were issued, the NPP Krsko Fire Hazard Analysis (Safe Shout down Separation Analysis Report), the ICISA Analysis of Core Damage Frequency Due to Fire at the NPP Krsko and IPEEE (Individual Plant External Event Examination) related to fire risk. The Fire Hazard Analysis Report utilizes a compliance - based deterministic approach to identification of fire area hazards. This report focuses on strict compliance from the perspective of US Nuclear Regulatory Commission (USNRC), standards, guidelines and acceptance criteria and does not consider variations to comply with the intent of the regulations. The probabilistic analysis methide used in the ICISA and IPEEE report utilizes a risk based nad intent based approach in determining critical at-risk fire areas. NPP Krsko has already completed the following suggestions/recommendations from the above and OSART reports in order to comply with Appendix R: Installation of smoke detectors in the Control Room; Installation of Emergency Lighting in some plant areas and of Remote Shout down panels; Extension of Sound Power Communication System; Installation of Fire Annunciator Panel at the On-site Fire Brigade Station; Installation of Smoke Detection System in the (a) Main Control Room Panels, (b) Essential Service Water Building. (c) Component Cooling Building pump area, chiller area and HVAC area, (d) Auxiliary Building Safety pump rooms, (e) Fuel Handling room, (f) Intermediate Building AFFW area and compressor room, and (g) Tadwaste building; inclusion of Auxiliary operators in the Fire Brigade; training of Fire Brigade Members in Plant Operation (9 week course); Development of Fire Door Inspection and

Characterization of non-calcareous 'thin' red clay from south-eastern Brazil: applicability in wall tile manufacture

Energy Technology Data Exchange (ETDEWEB)

Sousa, S. J.G.; Holanda, J. N.F., [Grupo de Materiais Ceramicos - LAMAV-CCT, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ (Brazil)

2012-04-15

In this work the use of 'thin' red clay from south-eastern Brazil (Campos dos Goytacazes, RJ) as raw material for the manufacture of wall tile was investigated. A wide range of characterization techniques was employed, including X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), grain-size analysis, and thermogravimetric analysis. The wall tile body was prepared by the dry process. The tile pieces were uniaxially pressed and fired between 1080 - 1180 deg C using a fast-firing cycle. The following technological properties were determined: linear shrinkage, water absorption, apparent density, and flexural strength. The development of the microstructure was followed by SEM and XRD analyses. It was found that the 'thin' red clay is kaolinitic type containing a substantial amount of quartz. The results also showed that the 'thin' red clay could be used in the manufacture of wall tiles, as they present properties compatible with those specified for class BIII of ISO 13006 standard. (author)

Research on fire extinguishing and disaster measures techniques for nuclear facilities

International Nuclear Information System (INIS)

Tsuruda, Takashi; Amano, Hisanori; Liao, Chihong

2004-01-01

As for a fire of alkali metals in nuclear facilities, measures to cope with the situation should be prepared. It has been experimentally investigated with a success to stabilize and treat safe in the air the leavings of burned sodium, which were extinguished by the nitrogen and poured with fire extinguishing powder for metal fire. Furthermore research and development has been conducted on a series of robots such as installing protection wall between radiation sources and victims and carrying victims out of the disaster room. Basic functional experiments on key components of robot system have been carried out using a trial product. Total control system of a series of robots will be updated based on control mechanism and software of a trial robot system. (T. Tanaka)

Fire management strategies to maintain species population processes in a fragmented landscape of fire-interval extremes.

Science.gov (United States)

Tulloch, Ayesha I T; Pichancourt, Jean-Baptiste; Gosper, Carl R; Sanders, Angela; Chadès, Iadine

2016-10-01

Changed fire regimes have led to declines of fire-regime-adapted species and loss of biodiversity globally. Fire affects population processes of growth, reproduction, and dispersal in different ways, but there is little guidance about the best fire regime(s) to maintain species population processes in fire-prone ecosystems. We use a process-based approach to determine the best range of fire intervals for keystone plant species in a highly modified Mediterranean ecosystem in southwestern Australia where current fire regimes vary. In highly fragmented areas, fires are few due to limited ignitions and active suppression of wildfire on private land, while in highly connected protected areas fires are frequent and extensive. Using matrix population models, we predict population growth of seven Banksia species under different environmental conditions and patch connectivity, and evaluate the sensitivity of species survival to different fire management strategies and burning intervals. We discover that contrasting, complementary patterns of species life-histories with time since fire result in no single best fire regime. All strategies result in the local patch extinction of at least one species. A small number of burning strategies secure complementary species sets depending on connectivity and post-fire growing conditions. A strategy of no fire always leads to fewer species persisting than prescribed fire or random wildfire, while too-frequent or too-rare burning regimes lead to the possible local extinction of all species. In low landscape connectivity, we find a smaller range of suitable fire intervals, and strategies of prescribed or random burning result in a lower number of species with positive growth rates after 100 years on average compared with burning high connectivity patches. Prescribed fire may reduce or increase extinction risk when applied in combination with wildfire depending on patch connectivity. Poor growing conditions result in a significantly

A case study on the structural assessment of fire damaged building

Science.gov (United States)

Osman, M. H.; Sarbini, N. N.; Ibrahim, I. S.; Ma, C. K.; Ismail, M.; Mohd, M. F.

2017-11-01

This paper presents a case study on the structural assessment of building damaged by fire and discussed on the site investigations and test results prior to determine the existing condition of the building. The building was on fire for about one hour before it was extinguished. In order to ascertain the integrity of the building, a visual inspection was conducted for all elements (truss, beam, column and wall), followed by non-destructive, load and material tests. The load test was conducted to determine the ability of truss to resist service load, while the material test to determine the residual strength of the material. At the end of the investigation, a structural analysis was carried out to determine the new factor of safety by considering the residual strength. The highlighted was on the truss element due to steel behaviour that is hardly been predicted. Meanwhile, reinforced concrete elements (beam, column and wall) were found externally affected and caused its strength to be considered as sufficient for further used of building. The new factor of safety is equal to 2, considered as the minimum calculated value for the truss member. Therefore, this fire damaged building was found safe and can be used for further application.

Equivalent elastic moduli of a zigzag single-walled carbon nanotube given by uniform radial deformation

International Nuclear Information System (INIS)

Li Ying; Qiu Xinming; Yin Yajun; Yang Fan; Fan Qinshan

2009-01-01

Under hydrostatic pressure, the equivalent elastic moduli of a zigzag single-walled carbon nanotube (SWNT) are analytically determined by energy conservation, with the consideration of the covalent bond deformation. The theoretical predictions on the transverse mechanical properties of a zigzag SWNT agree reasonably well with those given by the molecular structures mechanics simulations and also the ab initio calculations. From the simple geometry calculation, the circumferential strain is about 2-3 times of the axial strain of a zigzag SWNT under hydrostatic pressure. The bulk modulus of a zigzag SWNT is found to be 3/7 times of its radial Young's modulus.

Temperature dependence of photoconductivity at 0.7 eV in single-wall carbon nanotube films

Directory of Open Access Journals (Sweden)

Yukitaka Matsuoka, Akihiko Fujiwara, Naoki Ogawa, Kenjiro Miyano, Hiromichi Kataura, Yutaka Maniwa, Shinzo Suzuki and Yohji Achiba

2003-01-01

Full Text Available Temperature dependence of photoconductivity has been investigated for single-wall carbon nanotube films at 0.7 eV. In order to clarify the effect of atmosphere on photoconductivity, measurements have been performed under helium and nitrogen gas flow in the temperature range from 10 K to room temperature (RT and from 100 K to RT, respectively. Photoconductive response monotonously increases with a decrease in temperature and tends to saturate around 10 K. No clear difference in photoconductive response under different atmosphere was observed. We discuss the mechanism of photoconductivity at 0.7 eV.

A Review of Double-Walled and Triple-Walled Carbon Nanotube Synthesis and Applications

Directory of Open Access Journals (Sweden)

Kazunori Fujisawa

2016-04-01

Full Text Available Double- and triple-walled carbon nanotubes (DWNTs and TWNTs consist of coaxially-nested two and three single-walled carbon nanotubes (SWNTs. They act as the geometrical bridge between SWNTs and multi-walled carbon nanotubes (MWNTs, providing an ideal model for studying the coupling interactions between different shells in MWNTs. Within this context, this article comprehensively reviews various synthetic routes of DWNTs’ and TWNTs’ production, such as arc discharge, catalytic chemical vapor deposition and thermal annealing of pea pods (i.e., SWNTs encapsulating fullerenes. Their structural features, as well as promising applications and future perspectives are also discussed.

Reinforced Thermoplastic Polyimide with Dispersed Functionalized Single Wall Carbon Nanotubes

Science.gov (United States)

Lebron-Colon, Marisabel; Meador, Michael A.; Gaier, James R.; Sola, Francisco; Scheiman, Daniel A.; McCorkle, Linda S.

2010-01-01

Molecular pi-complexes were formed from pristine HiPCO single-wall carbon nanotubes (SWCNTs) and 1-pyrene- N-(4- N'-(5-norbornene-2,3-dicarboxyimido)phenyl butanamide, 1. Polyimide films were prepared with these complexes as well as uncomplexed SWCNTs and the effects of nanoadditive addition on mechanical, thermal, and electrical properties of these films were evaluated. Although these properties were enhanced by both nanoadditives, larger increases in tensile strength and thermal and electrical conductivities were obtained when the SWCNT/1 complexes were used. At a loading level of 5.5 wt %, the Tg of the polyimide increased from 169 to 197 C and the storage modulus increased 20-fold (from 142 to 3045 MPa). The addition of 3.5 wt % SWCNT/1 complexes increased the tensile strength of the polyimide from 61.4 to 129 MPa; higher loading levels led to embrittlement and lower tensile strengths. The electrical conductivities (DC surface) of the polyimides increased to 1 x 10(exp -4) Scm(exp -1) (SWCNT/1 complexes loading level of 9 wt %). Details of the preparation of these complexes and their effects on polyimide film properties are discussed.

Mediated Electron Transfer at Vertically Aligned Single-Walled Carbon Nanotube Electrodes During Detection of DNA Hybridization

Science.gov (United States)

Wallen, Rachel; Gokarn, Nirmal; Bercea, Priscila; Grzincic, Elissa; Bandyopadhyay, Krisanu

2015-06-01

Vertically aligned single-walled carbon nanotube (VASWCNT) assemblies are generated on cysteamine and 2-mercaptoethanol (2-ME)-functionalized gold surfaces through amide bond formation between carboxylic groups generated at the end of acid-shortened single-walled carbon nanotubes (SWCNTs) and amine groups present on the gold surfaces. Atomic force microscopy (AFM) imaging confirms the vertical alignment mode of SWCNT attachment through significant changes in surface roughness compared to bare gold surfaces and the lack of any horizontally aligned SWCNTs present. These SWCNT assemblies are further modified with an amine-terminated single-stranded probe-DNA. Subsequent hybridization of the surface-bound probe-DNA in the presence of complementary strands in solution is followed using impedance measurements in the presence of Fe(CN)6 3-/4- as the redox probe in solution, which show changes in the interfacial electrochemical properties, specifically the charge-transfer resistance, due to hybridization. In addition, hybridization of the probe-DNA is also compared when it is attached directly to the gold surfaces without any intermediary SWCNTs. Contrary to our expectations, impedance measurements show a decrease in charge-transfer resistance with time due to hybridization with 300 nM complementary DNA in solution with the probe-DNA attached to SWCNTs. In contrast, an increase in charge-transfer resistance is observed with time during hybridization when the probe-DNA is attached directly to the gold surfaces. The decrease in charge-transfer resistance during hybridization in the presence of VASWCNTs indicates an enhancement in the electron transfer process of the redox probe at the VASWCNT-modified electrode. The results suggest that VASWCNTs are acting as mediators of electron transfer, which facilitate the charge transfer of the redox probe at the electrode-solution interface.

Forest fire effects on transpiration: process modeling of sapwood area reduction

Science.gov (United States)

Michaletz, Sean; Johnson, Edward

2010-05-01

Transpiration is a hydrological process that is strongly affected by forest fires. In crown fires, canopy fine fuels (foliage, buds, and small branches) combust, which kills individual trees and stops transpiration of the entire stand. In surface fires (intensities ≤ 2500 kW m-1), however, effects on transpiration are less predictable becuase heat transfer from the passing fireline can injure or kill fine roots, leaves, and sapwood; post-fire transpiration of forest stands is thus governed by fire effects on individual tree water budgets. Here, we consider fire effects on cross-sectional sapwood area. A two-dimensional model of transient bole heating is used to estimate radial isotherms for a range of fireline intensities typical of surface fires. Isotherms are then used to drive three processes by which heat may reduce sapwood area: 1) necrosis of living cells in contact with xylem conduits, which prevents repair of natural embolism; 2) relaxation of viscoelastic conduit wall polymers (cellulose, hemicelloluse, and lignin), which reduces cross-sectional conduit area; and 3) boiling of metastable water under tension, which causes conduit embolism. Results show that these processes operate on different time scales, suggesting that fire effects on transpiration vary with time since fire. The model can be linked with a three-dimensional physical fire spread model to predict size-dependent effects on individual trees, which can be used to estimate scaling of individual tree and stand-level transpiration.

Sandwich-like singled-walled titania nanotube as a novel semiconductor electrode for quantum dot-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Dong, Cunku; Li, Xin; Fan, Xiujuan [Department of Chemistry, Harbin Institute of Technology, Harbin 150090 (China); Qi, Jingyao [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

2012-06-15

A novel sandwich-like singled-walled titania nanotube is designed as a photoanode in quantum dot-sensitized solar cells. It acts as a hollow coaxial nanocable, in which the injected electron is confined in the conducting layer for transport, guarded from electron recombination by the protective layers. An ultrafast interfacial electron transfer is also expected in this photoelectric system due to the unique nanoarchitecture. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Experiment research of slag renovation in the corner-fired boiler

Energy Technology Data Exchange (ETDEWEB)

Gong, Zhijun; Wu, Wenfei [Inner Mongolia Univ. of Science and Technology, Baotou (China). School of Energy and Environment

2013-07-01

Aiming at serious slag on the water wall around the burner of corner-fired boiler with low-ash-fusion-point coal, cold experimental model has been established. In this experiment, particle image velocimetry (PIV) has been employed to accurately measure aerodynamic field of burner region, and the experimental research of furnace slag renovation has been conducted through changing the burner jet arrangement. The experiment results show that it has significantly effect on aerodynamic field in the furnace by changing burner jet deflection angle. A reasonable actual tangential circle diameter can be formed through adjusting the burner jet deflection angle, to prevent primary air attacking the wall, and further more, to effectively prevent serious slag on the water wall around the burner.

Waterwall corrosion evaluation in coal-fired boilers using electrochemical measurements

Energy Technology Data Exchange (ETDEWEB)

Davis, K.; Lee, C.; Seeley, R.; Harding, S.; Heap, M.; Cox, W.

2000-07-01

Until recently, waterwall corrosion in North American coal-fired boilers was uncommon and relatively mild. However, the introduction of combustion modifications to reduce in-furnace NOx formation has led to notable increases in the frequency and severity of waterwall wastage. Reaction Engineering International (REI) has worked with the Department of Energy and EPRI to improve predictive capabilities and provide solutions for furnace wall wastage for a wide range of coal-fired furnaces. To date, this work has emphasized computational simulations. More recently, REI in partnership with Corrosion Management has begun complementary efforts to improve their services by evaluating technologies capable of determining the location/rate of high water wall wastage resulting from corrosion. After an evaluation of commercially available options, electrochemical noise (EN) technology has been chosen for continued development. This approach has been successfully applied to corrosion-related problems involving acid dewpoint corrosion in flue gas ductwork, FGD systems, cooling water systems, oil and gas production, and acid cleaning (Cox et al, 1999). This paper presents the results of preliminary testing of an EN probe in a high temperature environment typical of the lower furnace of a cyclone-fired boiler operating under staged conditions. The relationship between electrochemical responses and (1) stoichiometry and (2) local hydrogen sulfide concentration is investigated and the qualitative and quantitative usefulness of the approach for on-line risk management is considered.

Post wall fixation by lag screw only in associated both column fractures with posterior wall involvement.

Science.gov (United States)

Wang, Hu; Utku, Kandemir; Zhuang, Yan; Zhang, Kun; Fu, Ya-Hui; Wei, Xing; Wang, Peng-Fei; Cong, Yu-Xuan; Lei, Jin-Lai; Zhang, Bin-Fei

2017-07-01

To evaluate the quality of reduction, clinical outcomes and complications of associated both column acetabular fractures with posterior wall involvement that are treated through single ilioinguinal approach and fixation of posterior wall by lag screws only. We conducted a retrospective review involving ninety-nine consecutive patients with associated both column fractures of acetabulum treated through single ilioinguinal approach. Patients were divided into two groups. The first group consisted of 35 patients presented with both column fractures with posterior wall involvement that fixation performed with lag screws. This group was compared to a second group of 64 patients with both column fractures without posterior wall involvement. The quality of reduction was assessed using criteria described by Matta. The size of posterior wall fragment was measured. Functional outcome was evaluated using Modified Postel Merle D'Aubigne score. Radiographs at the latest follow up were analyzed for arthritis (Kellgren-Lawrence classification), and femoral head avascular necrosis (Ficat/Arlet classification). The study showed no significant differences in all preoperative variables (P>0.05). While intraoperative blood loss and operative time in group 1 were increased compared to group 2, the difference was not statistically significant (P>0.05). The height, relative depth and peripheral length of posterior wall respectively were 27.8±2.5mm (range: 24-35mm), 71.5±5.4% (range: 65-88%), 23.0±2.3mm (range: 17-28mm). The mean posterior wall fracture displacement is 5.0±3.2mm (range: 0-11mm). There was no difference regarding the quality of reduction between the two groups (P>0.05). The excellent to good clinical outcome was around 71.4% in the group 1 versus 73.4% in the group 2 at the final follow-up, this difference was not statistically significant (P>0.05). There was no difference in rate of complications between the two groups (P>0.05). Lag screws fixation of posterior wall

Fire simulation in large compartments with a fire model 'CFAST'. Part 1. Survey of applicability for analyzing air-temperature profile in compartments

International Nuclear Information System (INIS)

Hattori, Yasuo; Suto, Hitoshi; Shirai, Koji; Eguchi, Yuzuru; Sano, Tadashi

2012-01-01

The basic performance of numerical analysis of air-temperature profiles in large-scale compartments by using a zone model, CFAST (Consolidated model of Fire growth And Smoke Transport), which has been widely applied for fire protection design of buildings is examined. Special attentions are paid to the dependence of the setting boundary conditions and the choosing model parameters. The simulations carried out under the denkyoken-test conditions, in which the air-temperature profiles in compartments and the heat-release rate of a fire have been precisely measured, indicate that the CFAST has a capability to appropriately represent the time-histories of air-temperature in the high air-temperature layer generated in the vicinity of ceiling of the compartment which includes the source of a fire, by applying the proper boundary conditions, i.e., time-histories of air-temperature in the upper (high temperature) layer given by the CFAST agree well with those of observations. The sensitivity analysis in the simulations also reveals that the appropriately setting of the boundary-conditions, especially for the heat-release ratio from a fire and the heat-transfer rate from walls of compartments to ambient air is vital. Contrary to this, the impacts of choosing numerical parameters on the air-temperature analysis are quite small. (author)

Optimum diameter of a circulating fluidised bed combustor with negative wall heat flux

CSIR Research Space (South Africa)

Baloyi, J

2015-07-01

Full Text Available on irreversibilities in a 7 m circulating fluidised bed combustor with a negative wall heat flux, firing a mixture of air and solid pitch pine wood, was investigated. An analytical expression was derived that predicts the entropy generation rate, thereby...

Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

Science.gov (United States)

Han, Zhao Jun; Ostrikov, Kostya

2012-04-04

Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

International Nuclear Information System (INIS)

Diniz, Ginetom S.; Ulloa, Sergio E.

2014-01-01

We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

Spin-orbit coupling and the static polarizability of single-wall carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Diniz, Ginetom S., E-mail: ginetom@gmail.com; Ulloa, Sergio E. [Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701-2979 (United States)

2014-07-14

We calculate the static longitudinal polarizability of single-wall carbon tubes in the long wavelength limit taking into account spin-orbit effects. We use a four-orbital orthogonal tight-binding formalism to describe the electronic states and the random phase approximation to calculate the dielectric function. We study the role of both the Rashba as well as the intrinsic spin-orbit interactions on the longitudinal dielectric response, i.e., when the probing electric field is parallel to the nanotube axis. The spin-orbit interaction modifies the nanotube electronic band dispersions, which may especially result in a small gap opening in otherwise metallic tubes. The bandgap size and state features, the result of competition between Rashba and intrinsic spin-orbit interactions, result in drastic changes in the longitudinal static polarizability of the system. We discuss results for different nanotube types and the dependence on nanotube radius and spin-orbit couplings.

Synoptic-scale fire weather conditions in Alaska

Science.gov (United States)

Hayasaka, Hiroshi; Tanaka, Hiroshi L.; Bieniek, Peter A.

2016-09-01

Recent concurrent widespread fires in Alaska are evaluated to assess their associated synoptic-scale weather conditions. Several periods of high fire activity from 2003 to 2015 were identified using Moderate Resolution Imaging Spectroradiometer (MODIS) hotspot data by considering the number of daily hotspots and their continuity. Fire weather conditions during the top six periods of high fire activity in the fire years of 2004, 2005, 2009, and 2015 were analyzed using upper level (500 hPa) and near surface level (1000 hPa) atmospheric reanalysis data. The top four fire-periods occurred under similar unique high-pressure fire weather conditions related to Rossby wave breaking (RWB). Following the ignition of wildfires, fire weather conditions related to RWB events typically result in two hotspot peaks occurring before and after high-pressure systems move from south to north across Alaska. A ridge in the Gulf of Alaska resulted in southwesterly wind during the first hotspot peak. After the high-pressure system moved north under RWB conditions, the Beaufort Sea High developed and resulted in relatively strong easterly wind in Interior Alaska and a second (largest) hotspot peak during each fire period. Low-pressure-related fire weather conditions occurring under cyclogenesis in the Arctic also resulted in high fire activity under southwesterly wind with a single large hot-spot peak.

Analysis of Architectural Building Design Influences on Fire Spread in Densely Urban Settlement using Cellular Automata

Science.gov (United States)

Tambunan, L.; Salamah, H.; Asriana, N.

2017-03-01

This study aims to determine the influence of architectural design on the risk of fire spread in densely urban settlement area. Cellular Automata (CA) is used to analyse the fire spread pattern, speed, and the extent of damage. Four cells represent buildings, streets, and fields characteristic in the simulated area, as well as their flammability level and fire spread capabilities. Two fire scenarios are used to model the spread of fire: (1) fire origin in a building with concrete and wood material majority, and (2) fire origin in building with wood material majority. Building shape, building distance, road width, and total area of wall openings are considered constant, while wind is ignored. The result shows that fire spread faster in the building area with wood majority than with concrete majority. Significant amount of combustible building material, absence of distance between buildings, narrow streets and limited fields are factors which influence fire spread speed and pattern as well as extent of damage when fire occurs in the densely urban settlement area.

Surface tailored single walled carbon nanotubes as catalyst support for direct methanol fuel cell

Science.gov (United States)

Kireeti, Kota V. M. K.; Jha, Neetu

2017-10-01

A strategy for tuning the surface property of Single Walled Carbon Nanotubes (SWNTs) for enhanced methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) along with methanol tolerance is presented. The surface functionality is tailored using controlled acid and base treatment. Acid treatment leads to the attachment of carboxylic carbon (CC) fragments to SWNT making it hydrophilic (P3-SWNT). Base treatment of P3-SWNT with 0.05 M NaOH reduces the CCs and makes it hydrophobic (P33-SWNT). Pt catalyst supported on the P3-SWNT possesses enhanced MOR whereas that supported on P33-SWNT not only enhances ORR kinetics but also possess good tolerance towards methanol oxidation as verified by the electrochemical technique.

Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

KAUST Repository

Jiwuer, Jilili

2014-07-07

We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

Raman spectroscopic investigations of swift heavy ion irradiation effects in single-walled carbon nanotubes

International Nuclear Information System (INIS)

Olejniczak, A.; Skuratov, V.A.; Lukaszewicz, J.P.

2013-01-01

In this study, we report the results on swift heavy ion irradiation effects in single-walled carbon nanotubes (SWNTs). Buckypapers, prepared of CVD grown, SWNTs were irradiated at room temperature with 167 MeV Xe ions to fluences in the range of 6×10 11 - 6.5×10 13 cm -2 and investigated using Raman spectroscopy. We observed a rich set of features in the intermediate frequency mode region. Some of them, being defect-induced, resembled fairly well the phonon density of states (DOS) of nanocrystalline glassy carbon. Analysis of the RBM modes has shown that the broader metallic tubes are characterized by higher radiation stability than thinner semiconducting ones. (authors)

Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

KAUST Repository

Jiwuer, Jilili; Abdurahman, Ayjamal; Gü lseren, Oğuz; Schwingenschlö gl, Udo

2014-01-01

We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

Feasibility of applying coal-fired boiler technology to process heaters

Energy Technology Data Exchange (ETDEWEB)

O' Sullivan, T F

1978-01-01

The preponderance of coal in US fossil fuel reserves has raised the question of the conversion of hydrocarbon process heaters to coal firing. A review undertaken in 1977 by an API sub-committee concluded that neither existing heaters nor existing heater designs were capable of modification or revision to burn coal, and that new coal-fired design consistent with process requirements would be needed for this purpose. In recognition of this need a cooperative investigation was undertaken by Combustion Engineering and Lummus. The present paper, reporting on this investigation, reviews existing coal-fired boiler equipment and techniques and describes their adaptation to the development of a design concept for a coal-fired process heater. To this end, the design parameters for both steam boilers and fired heaters have been compared and have been incorporated into a workable coal-fired process heater design which includes the following features; a coutant bottom for ash removal, an ash-hopper located under both radiant and convection chambers, a tangent type finned wall construction, a straight through gas flow pattern, a vertical tube convection section, horizontal firing using round burners, and an overall geometry allowing a coil arrangement capable of accommodating varying numbers of parallel serpentine coils. These features are integrated into a conceptual heater design which is detailed in a series of illustrations.

Development of Cost Effective Oxy-Combustion Retrofitting for Coal-Fired Boilers

Energy Technology Data Exchange (ETDEWEB)

Hamid Farzan

2010-12-31

The overall objective of this project is to further develop the oxy-combustion technology for commercial retrofit in existing wall-fired and Cyclone boilers by 2012. To meet this goal, a research project was conducted that included pilot-scale testing and a full-scale engineering and economic analysis.

Charge transfer at junctions of a single layer of graphene and a metallic single walled carbon nanotube.

Science.gov (United States)

Paulus, Geraldine L C; Wang, Qing Hua; Ulissi, Zachary W; McNicholas, Thomas P; Vijayaraghavan, Aravind; Shih, Chih-Jen; Jin, Zhong; Strano, Michael S

2013-06-10

Junctions between a single walled carbon nanotube (SWNT) and a monolayer of graphene are fabricated and studied for the first time. A single layer graphene (SLG) sheet grown by chemical vapor deposition (CVD) is transferred onto a SiO₂/Si wafer with aligned CVD-grown SWNTs. Raman spectroscopy is used to identify metallic-SWNT/SLG junctions, and a method for spectroscopic deconvolution of the overlapping G peaks of the SWNT and the SLG is reported, making use of the polarization dependence of the SWNT. A comparison of the Raman peak positions and intensities of the individual SWNT and graphene to those of the SWNT-graphene junction indicates an electron transfer of 1.12 × 10¹³ cm⁻² from the SWNT to the graphene. This direction of charge transfer is in agreement with the work functions of the SWNT and graphene. The compression of the SWNT by the graphene increases the broadening of the radial breathing mode (RBM) peak from 3.6 ± 0.3 to 4.6 ± 0.5 cm⁻¹ and of the G peak from 13 ± 1 to 18 ± 1 cm⁻¹, in reasonable agreement with molecular dynamics simulations. However, the RBM and G peak position shifts are primarily due to charge transfer with minimal contributions from strain. With this method, the ability to dope graphene with nanometer resolution is demonstrated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photo-nano immunotherapy for metastatic breast cancer using synergistic single-walled carbon nanotubes and glycated chitosan

Science.gov (United States)

Zhou, Feifan; Hasanjee, Aamr; Doughty, Austin; West, Connor; Liu, Hong; Chen, Wei R.

2015-03-01

In our previous work, we constructed a multifunctional nano system, using single-walled carbon nanotube (SWNT) and glycated chitosan (GC), which can synergize photothermal and immunological effects. To further confirm the therapy efficacy, with a metastatic mouse mammary tumor model (4T1), we investigate the therapy effects and immune response induced by SWNT-GC, under laser irradiation. Laser+SWNT-GC treatment not only suppressed the prime tumor, but also induced antitumor immune response. It could be developed into a promising treatment modality for the metastatic breast cancer.

Controlling Structural Characteristics of Single-Walled Carbon Nanotubes (SWNT) by Tailoring Catalyst Composition and Synthesis Conditions

International Nuclear Information System (INIS)

Resasco, Daniel E.

2010-01-01

This report shows the extensive research on the mechanism responsible for the formation of single walled carbon nanotubes in order to get control over their structural parameters (diameter and chirality). Catalyst formulations, pre-treatment conditions, and reaction conditions are described in detail as well as mechanisms to produce nanotubes structures of specific arrays (vertical forest, nanotube pillars). Applications of SWNT in different fields are also described in this report. In relation to this project five students have graduated (3 PhD and 2 MS) and 35 papers have been published.

Functionalization of silicon-doped single walled carbon nanotubes at the doping site: An ab initio study

International Nuclear Information System (INIS)

Song Chen; Xia Yueyuan; Zhao Mingwen; Liu Xiangdong; Li Feng; Huang Boda; Zhang Hongyu; Zhang Bingyun

2006-01-01

We performed ab initio calculations on the cytosine-functionalized silicon-doped single walled carbon nanotubes (SWNT). The results show that silicon substitutional doping to SWNT can dramatically change the atomic and electronic structures of the SWNT. And more importantly, it may provide an efficient pathway for further sidewall functionalization to synthesize more complicated SWNT based complex materials, for example, our previously proposed base-functionalized SWNTs, because the doping silicon atom can improve the reaction activity of the tube at the doping site due to its preference to form sp3 hybridization bonding

Catalyst Design Using Nanoporous Iron for the Chemical Vapor Deposition Synthesis of Single-Walled Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Tarek M. Abdel-Fattah

2013-01-01

Full Text Available Single-walled carbon nanotubes (SWNTs have been synthesized via a novel chemical vapor deposition (CVD approach utilizing nanoporous, iron-supported catalysts. Stable aqueous dispersions of the CVD-grown nanotubes using an anionic surfactant were also obtained. The properties of the as-produced SWNTs were characterized through atomic force microscopy and Raman spectroscopy and compared with purified SWNTs produced via the high-pressure CO (HiPCO method as a reference, and the nanotubes were observed with greater lengths than those of similarly processed HiPCO SWNTs.

Wildland fire limits subsequent fire occurrence

Science.gov (United States)

Sean A. Parks; Carol Miller; Lisa M. Holsinger; Scott Baggett; Benjamin J. Bird

2016-01-01

Several aspects of wildland fire are moderated by site- and landscape-level vegetation changes caused by previous fire, thereby creating a dynamic where one fire exerts a regulatory control on subsequent fire. For example, wildland fire has been shown to regulate the size and severity of subsequent fire. However, wildland fire has the potential to influence...

Influence of the contact geometry on single-walled carbon nanotube/Si photodetector response

Science.gov (United States)

Scagliotti, Mattia; Salvato, Matteo; De Crescenzi, Maurizio; Boscardin, Maurizio; Castrucci, Paola

2018-03-01

A systematic study of the optical response of photodetectors based on carbon nanotube/Si heterojunctions is performed by measuring the responsivity, the detectivity and the time response of the devices with different contact configurations. The sensors are obtained by dry transferring single-walled carbon nanotube films on the surface of n-doped Si substrate provided with a multifinger contact geometry. The experimental data show a consistent improvement of the photodetector parameters with the increase of the number of fingers without affecting the carbon nanotube film thickness for increase its optical transmittance as in previous experiments. The role of the electrical resistance of the carbon nanotube film is discussed. The obtained results confirm the method and suggest new perspectives in the use of nanostructured materials as part of semiconducting optical devices.

Vertically aligned single-walled carbon nanotubes by chemical assembly--methodology, properties, and applications.

Science.gov (United States)

Diao, Peng; Liu, Zhongfan

2010-04-06

Single-walled carbon nanotubes (SWNTs), as one of the most promising one-dimension nanomaterials due to its unique structure, peculiar chemical, mechanical, thermal, and electronic properties, have long been considered as an important building block to construct ordered alignments. Vertically aligned SWNTs (v-SWNTs) have been successfully prepared by using direct growth and chemical assembly strategies. In this review, we focus explicitly on the v-SWNTs fabricated via chemical assembly strategy. We provide the readers with a full and systematic summary covering the advances in all aspects of this area, including various approaches for the preparation of v-SWNTs using chemical assembly techniques, characterization, assembly kinetics, and electrochemical properties of v-SWNTs. We also review the applications of v-SWNTs in electrochemical and bioelectrochemical sensors, photoelectric conversion, and scanning probe microscopy.

CVD-grown horizontally aligned single-walled carbon nanotubes: synthesis routes and growth mechanisms.

Science.gov (United States)

Ibrahim, Imad; Bachmatiuk, Alicja; Warner, Jamie H; Büchner, Bernd; Cuniberti, Gianaurelio; Rümmeli, Mark H

2012-07-09

Single-walled carbon nanotubes (SWCNTs) have attractive electrical and physical properties, which make them very promising for use in various applications. For some applications however, in particular those involving electronics, SWCNTs need to be synthesized with a high degree of control with respect to yield, length, alignment, diameter, and chirality. With this in mind, a great deal of effort is being directed to the precision control of vertically and horizontally aligned nanotubes. In this review the focus is on the latter, horizontally aligned tubes grown by chemical vapor deposition (CVD). The reader is provided with an in-depth review of the established vapor deposition orientation techniques. Detailed discussions on the characterization routes, growth parameters, and growth mechanisms are also provided. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pt nanoparticle modified single walled carbon nanotube network electrodes for electrocatalysis: control of the specific surface area over three orders of magnitude

NARCIS (Netherlands)

Miller, T.S.; Sansuk, S.; Lai, Stanley; Macpherson, J.V.; Unwin, P.R.

2015-01-01

The electrodeposition of Pt nanoparticles (NPs) on two-dimensional single walled carbon nanotube (SWNT) network electrodes is investigated as a means of tailoring electrode surfaces with a well-defined amount of electrocatalytic material. Both Pt NP deposition and electrocatalytic studies are

Slagging and fouling evaluation of PC-fired boilers using AshPro{sup SM}

Energy Technology Data Exchange (ETDEWEB)

Ma, Zhanhua; Iman, Felicia; Lu, Pisi [SmartBurn, LLC, Madison, WI (United States)

2013-07-01

SmartBurn {sup registered} applied AshPro{sup SM} model to two 512 MW Tangential-fired (T-fired) boilers firing US western sub- bituminous coals to evaluate the boiler slagging behaviors with different operating conditions and OFA. The boiler convective pass fouling behaviors with three different coals were also evaluated. The slagging evaluation results indicate that the OFA configuration and air flow distribution have dramatically impacts on the ash impaction rates and slagging patterns on the furnace walls. Deposit growth and strength vary at the different regions of the furnace walls. The fouling evaluation reveals that the tube bank configuration, the amount of incoming ash, the profiles of flue gas temperature, velocity, and species all have significant impacts on fouling deposit formation, growth, and strength development. In addition, the varying ash particle sizes and chemical compositions from different coals also play important roles on the fouling deposit strength development and removal. The investigation demonstrated that AshPro{sup SM} model can be used to evaluate localized slagging and fouling problems that are related to specific boiler configuration and operating conditions. It can be used to identify the major causes of ash deposition and can guide changes in boiler operation.

Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

Energy Technology Data Exchange (ETDEWEB)

Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhai, Liang-Jun [The School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001 (China); Hua, Ling-Ling [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China)

2016-01-15

The effect of magnetic spin correlation on the thermodynamic properties of Heisenberg ferromagnetic single-walled nanotubes are comprehensively investigated by use of the double-time Green's function method. The influence of temperature, spin quantum number, diameter of the tube, anisotropy strength and external magnetic field to internal energy, free energy, and magnon specific heat are carefully calculated. Compared to the mean field approximation, the consideration of the magnetic correlation effect significantly improves the internal energy values at finite temperature, while it does not so near zero temperature, and this effect is related to the diameter of the tube, anisotropy strength, and spin quantum number. The magnetic correlation effect lowers the internal energy at finite temperature. As a natural consequence of the reduction of the internal energy, the specific heat is reduced, and the free energy is elevated. - Highlights: • Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes (HFM-SWNTs) are investigated. • The magnetic correlations effect has a considerable contribution to the thermodynamics properties of HFM-SWNTs. • Magnetic correlation effects are always to lower the internal energy at finite temperature. • At Curie point, magnetic correlation energy is much less than zero. • The peak values of magnon specific heat curves rise and shift right towards higher temperatures with the diameter of tubes, the anisotropy strength, and the spin quantum number rising.

Dislocations in single hemp fibres-investigations into the relationship of structural distortions and tensile properties at the cell wall level

DEFF Research Database (Denmark)

Thygesen, Lisbeth Garbrecht; Eder, M.; Burgert, I.

2007-01-01

The relationship between dislocations and mechanical properties of single hemp fibres (Cannabis sativa L. var. Felina) was studied using a microtensile testing setup in a 2-fold approach. In a first investigation the percentage of dislocations was quantified using polarized light microscopy (PLM......) prior to microtensile testing of the fibres. In a second approach PLM was used to monitor the dislocations while straining single fibres. The first part of the study comprised 53 hemp fibres with up to 20% of their cell wall consisting of dislocations. For this data set the percentage of dislocations...

A New Design Method for Industrial Portal Frames in Fire

Directory of Open Access Journals (Sweden)

Y. Song

2009-01-01

Full Text Available Industrial portal frames near to other buildings must keep their vertical walls standing in fire in order to prevent fire spread.  A recently developed analysis, implemented in the program Vulcan, using a combination of static and dynamic solvers, has shown that the strong base connections recommended by the current design method may not always lead to conservative design. A second-phase failure mechanism observed in numerical modelling, and the critical temperature at which final run-away collapse occurs, may be higher than the temperature at which the roof frame initially loses its stability, because a re-stabilisation often happens.  A new method for estimating critical temperatures of portal frames in fire, using these two failure mechanisms, is presented. Numerical tests on typical industrial frames are used to calibrate this new method. 

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

Energy Technology Data Exchange (ETDEWEB)

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

2015-04-07

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

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

International Nuclear Information System (INIS)

Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A.; Wahab, Muhammad A.; Alam, Muhammad A.; Li, Yuhang; Tomic, Bojan; Huang, Jiyuan; Burns, Branden; Song, Jizhou; Huang, Yonggang

2015-01-01

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

Burning behavior in a poor-ventilation compartment fire - ghosting fire

International Nuclear Information System (INIS)

Sugawa, Osami; Kawagoe, Kunio; Oka, Yasushi

1991-01-01

We investigated compartment fire behavior under poor-ventilation conditions using a methyl alcohol pool fire as the source with a diameter of 30 cm set in a tight box of 2 m (W)x3 m(L)x0.6 m(H). The temperatures in the box and the fuel, gas concentrations of CO, CO 2 , and O 2 , and the fuel consumption rate were measured simultaneously. The burning fuel surface level was kept constant during the test by means of an automatic fuel supply system. It was found that the flame begun to detach from the fuel surface as the oxygen concentration decreased to about 16%, and the color changed to pale blue. The flame detached completely from the fuel and a 'ghosting flame' was observed just under the ceiling which showed a thin pale blue flame and looked line an aurora. The oxygen concentration measured in the ghosting period under the ceiling was 9-10 vol%, and CO 2 was 4.5 vol% so that the oxygen of such concentration acted as in inert gas. CO 2 gas concentration looked almost a single-layer with gradient in the upper half part in ghosting period. Temperatures in the same layer decreased after ghosting occurred with gradient. For poor-ventilated fires, air exchange rate as 1.6-2.4 times/hr was estimated in the test; the burning rate decreased finally to about 1/6 of the fuel controlled fire. It has been tacitly assumed that the flame (reaction zone) and pyrolyzing material area (fuel) exit in almost the same zone, but ghosting fire is not necessarily the case. Therefore, extinguishment of ghosting fire which may occur in an enclosure with fuel and energy rich but poor-ventilation such as a power plant will be extremely difficult. (orig.)

Density functional theory prediction of pKa for carboxylated single-wall carbon nanotubes and graphene

Science.gov (United States)

Li, Hao; Fu, Aiping; Xue, Xuyan; Guo, Fengna; Huai, Wenbo; Chu, Tianshu; Wang, Zonghua

2017-06-01

Density functional calculations have been performed to investigate the acidities for the carboxylated single-wall carbon nanotubes and graphene. The pKa values for different COOH-functionalized models with varying lengths, diameters and chirality of nanotubes and with different edges of graphene were predicted using the SMD/M05-2X/6-31G* method combined with two universal thermodynamic cycles. The effects of following factors, such as, the functionalized position of carboxyl group, the Stone-Wales and single vacancy defects, on the acidity of the functionalized nanotube and graphene have also been evaluated. The deprotonated species have undergone decarboxylation when the hybridization mode of the carbon atom at the functionalization site changed from sp2 to sp3 both for the tube and graphene. The knowledge of the pKa values of the carboxylated nanotube and graphene could be of great help for the understanding of the nanocarbon materials in many diverse areas, including environmental protection, catalysis, electrochemistry and biochemistry.

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}.

Avian response to fire in pine–oak forests of Great Smoky Mountains National Park following decades of fire suppression

Science.gov (United States)

Rose, Eli T.; Simons, Theodore R.

2016-01-01

Fire suppression in southern Appalachian pine–oak forests during the past century dramatically altered the bird community. Fire return intervals decreased, resulting in local extirpation or population declines of many bird species adapted to post-fire plant communities. Within Great Smoky Mountains National Park, declines have been strongest for birds inhabiting xeric pine–oak forests that depend on frequent fire. The buildup of fuels after decades of fire suppression led to changes in the 1996 Great Smoky Mountains Fire Management Plan. Although fire return intervals remain well below historic levels, management changes have helped increase the amount of fire within the park over the past 20 years, providing an opportunity to study patterns of fire severity, time since burn, and bird occurrence. We combined avian point counts in burned and unburned areas with remote sensing indices of fire severity to infer temporal changes in bird occurrence for up to 28 years following fire. Using hierarchical linear models that account for the possibility of a species presence at a site when no individuals are detected, we developed occurrence models for 24 species: 13 occurred more frequently in burned areas, 2 occurred less frequently, and 9 showed no significant difference between burned and unburned areas. Within burned areas, the top models for each species included fire severity, time since burn, or both, suggesting that fire influenced patterns of species occurrence for all 24 species. Our findings suggest that no single fire management strategy will suit all species. To capture peak occupancy for the entire bird community within xeric pine–oak forests, at least 3 fire regimes may be necessary; one applying frequent low severity fire, another using infrequent low severity fire, and a third using infrequently applied high severity fire.

Three-dimensional rotating flow of MHD single wall carbon nanotubes over a stretching sheet in presence of thermal radiation

Science.gov (United States)

Nasir, Saleem; Islam, Saeed; Gul, Taza; Shah, Zahir; Khan, Muhammad Altaf; Khan, Waris; Khan, Aurang Zeb; Khan, Saima

2018-05-01

In this article the modeling and computations are exposed to introduce the new idea of MHD three-dimensional rotating flow of nanofluid through a stretching sheet. Single wall carbon nanotubes (SWCNTs) are utilized as a nano-sized materials while water is used as a base liquid. Single-wall carbon nanotubes (SWNTs) parade sole assets due to their rare structure. Such structure has significant optical and electronics features, wonderful strength and elasticity, and high thermal and chemical permanence. The heat exchange phenomena are deliberated subject to thermal radiation and moreover the impact of nanoparticles Brownian motion and thermophoresis are involved in the present investigation. For the nanofluid transport mechanism, we implemented the Xue model (Xue, Phys B Condens Matter 368:302-307, 2005). The governing nonlinear formulation based upon the law of conservation of mass, quantity of motion, thermal field and nanoparticles concentrations is first modeled and then solved by homotopy analysis method (HAM). Moreover, the graphical result has been exposed to investigate that in what manner the velocities, heat and nanomaterial concentration distributions effected through influential parameters. The mathematical facts of skin friction, Nusselt number and Sherwood number are presented through numerical data for SWCNTs.

Neurons the decision makers, Part I: The firing function of a single neuron.

Science.gov (United States)

Saaty, Thomas

2017-02-01

This paper is concerned with understanding synthesis of electric signals in the neural system based on making pairwise comparisons. Fundamentally, every person and every animal are born with the talent to compare stimuli from things that share properties in space or over time. Comparisons always need experience to distinguish among things. Pairwise comparisons are numerically reciprocal. If a value is assigned to the larger of two elements that have a given property when compared with the smaller one, then the smaller has the reciprocal of that value when compared with the larger. Because making comparisons requires the reciprocal property, we need mathematics that can cope with division. There are four division algebras that would allow us to use our reciprocals arising from comparisons: The real numbers, the complex numbers, the non-commutative quaternions and the non-associative octonions. Rather than inferring function as from electric flow in a network, in this paper we infer the flow from function. Neurons fire in response to stimuli and their firings vary relative to the intensities of the stimuli. We believe neurons use some kind of pairwise comparison mechanism to determine when to fire based on the stimuli they receive. The ideas we develop here about flows are used to deduce how a system based on this kind of firing determination works and can be described. Furthermore the firing of neurons requires continuous comparisons. To develop a formula describing the output of these pairwise comparisons requires solving Fredholm's equation of the second kind which is satisfied if and only if a simple functional equation has solutions. The Fourier transform of the real solution of this equation leads to inverse square laws like those that are common in physics. The Fourier transform applied to a complex valued solution leads to Dirac type of firings. Such firings are dense in the very general fields of functions known as Sobolev spaces and thus can be used to