Sample records for tiny carbon tubes
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Stanislaus Wong
2017-12-09
"Nanovision: Nanotubes, Nanowires and Nanoparticles." Wong's "nanovision," as he explains, emerges from how the study of carbon and non-carbon forms of materials at the nanoscale reveals different morphological structures: some are tiny tubes, others are like wires, and others are in particle form. These minute nanostructures yield different properties as they are treated in different ways.
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Fast Response Shape Memory Effect Titanium Nickel (TiNi) Foam Torque Tubes
NASA Technical Reports Server (NTRS)
Jardine, Peter
2014-01-01
Shape Change Technologies has developed a process to manufacture net-shaped TiNi foam torque tubes that demonstrate the shape memory effect. The torque tubes dramatically reduce response time by a factor of 10. This Phase II project matured the actuator technology by rigorously characterizing the process to optimize the quality of the TiNi and developing a set of metrics to provide ISO 9002 quality assurance. A laboratory virtual instrument engineering workbench (LabVIEW'TM')-based, real-time control of the torsional actuators was developed. These actuators were developed with The Boeing Company for aerospace applications.
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NASA Astrophysics Data System (ADS)
Huang, C.; Chien, C.; Yang, T. F.; Lin, S.
2005-12-01
The Kaoping Slope off SW Taiwan represents the syn-collision accretionary prism characterized by active NW-trending folding - thrusting structures and high sedimentation rate favoring the formation of gas hydrate. For an assessment of gas hydrate potential in the Kaoping Slope off SW Taiwan, sedimentology, paleontology and geochemistry in box cores and piston cores were studied. BSRs are commonly found in seismic profiles in 400-600 m below seafloor of water depth 2500-1000 m. Active expulsions of methane were found along active thrust faults where sulfate/methane interface could be as shallow as 30 cm and the methane concentration of dissolved gases in bottom water and in pore-space of drilled core samples could be three-four order higher than the normal marine environments. Occurrences of authigenic carbonate and elongated pyrite tubes are correlated with shallow SMI depth and high methane content in bottom water and pore-space of sediment cores. Authigenic carbonates were found in seafloor surface and in 20-25 meters below seafloor. The authigenic carbonate nodules are characterized by irregular shape, whitish color, no visible microfossil, containing native sulfur, pyrites, gypsum, small open spaces, and very depleted carbon isotope (-54 ~ -43 per mil PDB). Tiny native sulfur and gypsum crystals were commonly found either on surface of foraminiferal tests and elongated pyrite tubes or in the authigenic carbonate nodules. Morphological measurements of elongated pyrite tubes show that they could represent pseudomorphs after three types of Pogonophora tube worm. Foraminifers are commonly filled by rhomboidal pyrites or cemented by pyrite crystals. Normal marine benthic foraminifers predominated by calcareous tests of slope fauna are associated with authigenic carbonate nodules in the study area, suggesting no major geochemistry effect on distribution of benthic foraminifers. Integrating sedimentology, paleontology and geochemistry characters, there could be high potential to have gas hydrate in the accretionary prism off SW Taiwan.
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You have two kidneys. They are fist-sized organs on either side of your backbone above your waist. The tubes inside filter and ... blood, taking out waste products and making urine. Kidney cancer forms in the lining of tiny tubes ...
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Tiny videos: a large data set for nonparametric video retrieval and frame classification.
Karpenko, Alexandre; Aarabi, Parham
2011-03-01
In this paper, we present a large database of over 50,000 user-labeled videos collected from YouTube. We develop a compact representation called "tiny videos" that achieves high video compression rates while retaining the overall visual appearance of the video as it varies over time. We show that frame sampling using affinity propagation-an exemplar-based clustering algorithm-achieves the best trade-off between compression and video recall. We use this large collection of user-labeled videos in conjunction with simple data mining techniques to perform related video retrieval, as well as classification of images and video frames. The classification results achieved by tiny videos are compared with the tiny images framework [24] for a variety of recognition tasks. The tiny images data set consists of 80 million images collected from the Internet. These are the largest labeled research data sets of videos and images available to date. We show that tiny videos are better suited for classifying scenery and sports activities, while tiny images perform better at recognizing objects. Furthermore, we demonstrate that combining the tiny images and tiny videos data sets improves classification precision in a wider range of categories.
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Development of Minimally Invasive Medical Tools Using Laser Processing on Cylindrical Substrates
NASA Astrophysics Data System (ADS)
Haga, Yoichi; Muyari, Yuta; Goto, Shoji; Matsunaga, Tadao; Esashi, Masayoshi
This paper reports micro-fabrication techniques using laser processing on cylindrical substrates for the realization of high-performance multifunctional minimally invasive medical tools with small sizes. A spring-shaped shape memory alloy (SMA) micro-coil with a square cross section has been fabricated by spiral cutting of a Ti-Ni SMA tube with a femtosecond laser. Small diameter active bending catheter which is actuated by hydraulic suction mechanism for intravascular minimally invasive diagnostics and therapy has also been developed. The catheter is made of a Ti-Ni super elastic alloy (SEA) tube which is processed by laser micromachining and a silicone rubber tube which covers the outside of the SEA tube. The active catheter is effective for insertion in branch of blood vessel which diverse in acute angle which is difficult to proceed. Multilayer metallization and patterning have been performed on glass tubes with 2 and 3 mm external diameters using maskless lithography techniques using a laser exposure system. Using laser soldering technique, a integrated circuit parts have been mounted on a multilayer circuit patterned on a glass tube. These fabrication techniques will effective for realization of high-performance multifunctional catheters, endoscopic tools, and implanted small capsules.
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Fast-Response-Time Shape-Memory-Effect Foam Actuators
NASA Technical Reports Server (NTRS)
Jardine, Peter
2010-01-01
Bulk shape memory alloys, such as Nitinol or CuAlZn, display strong recovery forces undergoing a phase transformation after being strained in their martensitic state. These recovery forces are used for actuation. As the phase transformation is thermally driven, the response time of the actuation can be slow, as the heat must be passively inserted or removed from the alloy. Shape memory alloy TiNi torque tubes have been investigated for at least 20 years and have demonstrated high actuation forces [3,000 in.-lb (approximately equal to 340 N-m) torques] and are very lightweight. However, they are not easy to attach to existing structures. Adhesives will fail in shear at low-torque loads and the TiNi is not weldable, so that mechanical crimp fits have been generally used. These are not reliable, especially in vibratory environments. The TiNi is also slow to heat up, as it can only be heated indirectly using heater and cooling must be done passively. This has restricted their use to on-off actuators where cycle times of approximately one minute is acceptable. Self-propagating high-temperature synthesis (SHS) has been used in the past to make porous TiNi metal foams. Shape Change Technologies has been able to train SHS derived TiNi to exhibit the shape memory effect. As it is an open-celled material, fast response times were observed when the material was heated using hot and cold fluids. A methodology was developed to make the open-celled porous TiNi foams as a tube with integrated hexagonal ends, which then becomes a torsional actuator with fast response times. Under processing developed independently, researchers were able to verify torques of 84 in.-lb (approximately equal to 9.5 Nm) using an actuator weighing 1.3 oz (approximately equal to 37 g) with very fast (less than 1/16th of a second) initial response times when hot and cold fluids were used to facilitate heat transfer. Integrated structural connections were added as part of the net shape process, eliminating the need for welding, adhesives, or mechanical crimping. Inexpensive net-shape processing was used, which reduces the cost of the actuator by over a factor of 10 over nonporous TiNi made by hot drawing of tube or electrical discharge machining. By forming the alloy as an open-celled foam, the surface area for heat transfer is dramatically increased, allowing for much faster response times. The technology also allows for netshape fabrication of the actuator, which allows for structural connections to be integrated into the actuator material, making these actuators significantly less expensive. Commercial applications include actuators for concepts such as the variable area chevron and nozzle in jet aircraft. Lightweight tube or rod components can be supplied to interested parties.
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Blood Transfusions (For Teens)
... person usually gets a blood transfusion through an intravenous line , a tiny tube that is inserted into ... blood cells. So some people getting treatment for cancer might need a transfusion of red blood cells ...
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Angioplasty and stent placement - carotid artery - discharge
... medlineplus.gov/ency/patientinstructions/000235.htm Angioplasty and stent placement - carotid artery - discharge To use the sharing ... the hospital. You may have also had a stent (a tiny wire mesh tube) placed in the ...
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Apollo 14 Lunar glass fragment known as Genesis bean
NASA Technical Reports Server (NTRS)
1972-01-01
A tiny green glass fragment taken from an Apollo 14 core tube sampling. Because of its scientific significance and shape, the fragment has been nicknamed the 'Genesis bean'. The main constituents are iron and magnesium.
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Bubble breakup phenomena in a venturi tube
NASA Astrophysics Data System (ADS)
Fujiwara, Akiko
2005-11-01
Microbubble has distinguished characteristics of large surface area to unit volume and small buoyancy, and it has advantages in many engineering fields. Recently microbubble generators with low energy and high performance are required to wide applications. In the present study, we propose one new effective technique to generate tiny bubbles with less than 200 μm diameter utilizing venturi tube under high void fraction condition. The objective of the present study is to elucidate the mechanism of bubble breakup phenomena in the venturi tube and to clarify the effects of parameters which are necessary to realize an optimum system experimentally. Experiment was conducted with void fraction of 4% and variation of liquid velocity from 9 to 26 m/s at the throat. Under low velocity condition, bubbles which were observed with a high speed camera parted gradually in a wide region. On the contrary under high velocity condition, bubbles expanded after passing through the throat and shrank rapidly. Since the speed of sound in gas-liquid system is extremely lower than that of single-phase flow, the bubble breakup phenomenon in the venturi tube is explained as the supersonic flow in a Laval nozzle. By rapid pressure recovery in diverging area, expanding bubbles collapse violently. The tiny bubbles are generated due to the surface instability of shrinking bubbles.
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Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou
2013-11-01
We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.
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Nano-spike Catalysts Convert Carbon Dioxide Directly into Ethanol
DOE Office of Scientific and Technical Information (OSTI.GOV)
Rondinone, Adam
2016-10-12
In a new twist to waste-to-fuel technology, scientists at the Department of Energy’s Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol. Their finding, which involves nanofabrication and catalysis science, was serendipitous.
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Nano-spike Catalysts Convert Carbon Dioxide Directly into Ethanol
Rondinone, Adam
2018-06-12
In a new twist to waste-to-fuel technology, scientists at the Department of Energyâs Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol. Their finding, which involves nanofabrication and catalysis science, was serendipitous.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-09
... Pipe and Tube From Turkey: Notice of Final Results of Antidumping Duty Administrative Review AGENCY... antidumping duty administrative review of certain welded carbon steel pipe and tube from Turkey. The... carbon steel pipe and tube from Turkey. See Certain Welded Carbon Steel Pipe and Tube from Turkey; Notice...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-13
... Pipes and Tubes from Thailand: Preliminary Results and Rescission, in Part, of Antidumping Duty... review of the antidumping duty order on circular welded carbon steel pipes and tubes from Thailand, in... welded carbon steel pipes and tubes from Thailand. See Antidumping Duty Order: Circular Welded Carbon...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-28
...] Certain Circular Welded Carbon Steel Pipes and Tubes From India, Thailand, and Turkey; Final Results of... circular welded carbon steel pipes and tubes from India, Thailand, and Turkey, pursuant to section 751(c..., Thailand, and Turkey. See Antidumping Duty Order; Certain Welded Carbon Steel Standard Pipes and Tubes from...
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MedlinePlus Videos and Cool Tools
... network of tiny blood vessels called capillaries, which are located in the walls of the alveoli. The ... time, the carbon dioxide molecules in the alveoli are blown out of the body with the next ...
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Advanced Carbon Materials Center Established At UK
UK Home Academics Athletics Medical Center Research Site Index Search UK University Master ] [research at UK] Advanced Carbon Materials Center Established At UK The tiny but mighty nanotube will continue to be the subject of several research projects at the University of Kentucky, thanks in part to a
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Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite
Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Moorhead, Arthur J.
1998-01-01
In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process.
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... side, the gas that makes soda fizzy), and methane (say: METH-ain) are made when food is ... bad. Tiny amounts of hydrogen, carbon dioxide, and methane combine with hydrogen sulfide (say: SUHL-fyde) and ...
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Shape memory alloy TiNi actuators for twist control of smart wing designs
NASA Astrophysics Data System (ADS)
Jardine, A. Peter; Kudva, Jayanth N.; Martin, Christopher A.; Appa, Kari
1996-05-01
On high performance military aircraft, small changes in both wing twist and wing camber have the potential to provide substantial payoffs in terms of additional lift and enhanced maneuverability. To achieve the required wing shape, actuators made of smart materials are currently being studied under an ARPA/WL contract for a subscale model of a fighter aircraft. The use of the shape memory alloy TiNi for wing twist actuation was investigated using shape memory effect (SME) torque tube actuator configurations. The actuator configurations were sized to fit inside a 16% scale model of an aircraft wing and the torque's supplied to the wing were similarly calculated from full-scale requirements. The actuator systems were tested in a conventional laboratory setting. Design and calibration of the actuators for wing twist are discussed.
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Collector surface for a microwave tube comprising a carbon-bonded carbon-fiber composite
Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Moorhead, A.J.
1998-07-28
In a microwave tube, an improved collector surface coating comprises a porous carbon composite material, preferably a carbon-bonded carbon fiber composite having a bulk density less than about 2 g/cc. Installation of the coating is readily adaptable as part of the tube manufacturing process. 4 figs.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-11-15
... DEPARTMENT OF COMMERCE International Trade Administration [A-533-502] Certain Welded Carbon Steel... order on certain welded carbon steel standard pipes and tubes from India. The period of review is May 1... carbon steel standard pipes and tubes from India. See Certain Welded Carbon Steel Standard Pipes and...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-04-09
... Pipes and Tubes From Thailand: Preliminary Results of Antidumping Duty Administrative Review; 2011- 2012... on circular welded carbon steel pipes and tubes from Thailand. This review covers two producers... welded carbon steel pipes and tubes from Thailand.\\1\\ The merchandise is classifiable under the...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-20
... Pipes and Tubes From Thailand: Final Results of Antidumping Duty Administrative Review AGENCY: Import... Thailand. The review was requested by Allied Tube and Conduit Corporation (Allied Tube), by Wheatland Tube... antidumping duty order on pipes and tubes from Thailand. See Circular Welded Carbon Steel Pipes and Tubes from...
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Schmitz, Andreas; Schmid, Carolin; de Boor, Johannes; Müller, Eckhard
2017-03-01
Filled cobalt-antimony based skutterudites have proven themselves as very promising thermoelectric materials for generator applications in an intermediate temperature range between 400 and 800 K due to their high figure of merit. Besides the functional thermoelectric properties also the skutterudites’ mechanical properties play an important role to withstand external mechanical and internal thermomechanical loads during operation. Properties of interest are hardness as well as fracture toughness and resistance to fatigue. Carbon nano tubes are well known for their high tensile strength and may therefore be used to increase the mechanical strength of composite materials. Additionally, the thermoelectric properties of the composite material might benefit from the high electrical conductivity of carbon nano tubes and increased phonon scattering at interfaces between matrix and carbon nano tube. A main precondition for benefiting from embedded nano-tubes is to achieve a homogeneous distribution of the CNTs and good adhesion between carbon nano tube and matrix material. In this work we present the influence of the introduction of multi-walled carbon nano tubes on the thermoelectric and mechanical properties of p-type skutterudites Ce(0.14)La(0.06)Co(2)Fe(2)Sb(12). The influence of different carbon nano tube concentrations and preparation routes on the resulting composite material’s thermoelectric, mechanical and microstructural properties is studied. A reduction of electrical and thermal conductivity as well as fracture strength is observed with increasing carbon nano tube content which is attributed to strong agglomeration of the nano tubes. The results underline the pivotal role of a homogeneous distribution of the carbon nano tubes for improving the mechanical properties of skutterudites.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-15
... Pipes and Tubes from Thailand: Court Decision Not in Harmony with Final Results of Administrative Review... welded carbon steel pipes and tubes from Thailand covering the period March 1, 2006 through February 28, 2007. Circular Welded Carbon Steel Pipes and Tubes from Thailand: Final Results of Antidumping Duty...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-05-21
... Steel Pipes and Tubes From Thailand: Extension of Time Limit for Final Results of Antidumping Duty... carbon steel pipes and tubes from Thailand. See Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results and Rescission, in Part, of Antidumping Duty Administrative Review, 75 FR...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-01-03
... Pipes and Tubes From Turkey; Amended Final Results of Antidumping Duty Administrative Review; 2010 to... administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Turkey... Act). \\1\\ See Circular Welded Carbon Steel Pipes and Tubes from Turkey; Final Results of Antidumping...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-17
... Pipes and Tubes From India, Thailand, and Turkey; Certain Circular Welded Non-Alloy Steel Pipe From... on (1) certain circular welded carbon steel pipes and tubes from India, Thailand, and Turkey; (2... circular welded carbon steel pipes and tubes from Turkey would likely lead to continuation or recurrence of...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-19
... Pipe and Tube From Turkey: Notice of Final Antidumping Duty Administrative Review AGENCY: Import... administrative review of certain welded carbon steel pipe and tube from Turkey. This review covers four producers... Administrative Review of Certain Welded Carbon Steel Pipe and Tube from Turkey: Selection of Respondents for...
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NASA Technical Reports Server (NTRS)
Misencik, J. A.
1983-01-01
Tubes of CG-27 alloy, filled with hydrogen doped with various amounts of carbon dioxide and carbon monoxide, were heated in a diesel fuel fired Stirling engine simulator materials test rig for 100 hours at 820 C and at a gas pressure of 15 MPa to determine the effectiveness of the dopants in reducing hydrogen permeation through the hot tube wall. This was done for clean as-heat treated tubes and also for tubes that had previously been exposed for 100 hours to hydrogen doped with 1.0 volume percent carbon dioxide to determine if the lower levels of dopant could maintain a low hydrogen permeation through the hot tube wall. Carbon dioxide, as a dopant in hydrogen, was most effective in reducing hydrogen permeation through clean tubes and in maintaining low hydrogen permeation after prior exposure to 1.0 volume percent carbon dioxide. Only the lowest level of carbon dioxide (0.05 volume percent) was not as effective in the clean or prior exposed tubes. Carbon monoxide as a dopant in hydrogen was less effective than carbon dioxide at a given concentration level. Of the four dopant levels studied; 1.0, 0.5, 0.2, and 0.05 volume percent carbon monoxide, only the 1.0 and 0.5 volume percent were effective in reducing and maintaining low hydrogen permeation through the CG-27.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-19
... Tube From Turkey: Final Results of Expedited Sunset Review of Countervailing Duty Order AGENCY: Import... welded carbon steel pipe and tube from Turkey pursuant to section 751(c) of the Tariff Act of 1930, as... INFORMATION: Background The CVD order on welded carbon steel pipe and tube from Turkey was published in the...
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Kim, Jae-Woo; Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho
2014-02-14
Highly reliable field electron emitters were developed using a formulation for reproducible damage-free carbon nanotube (CNT) composite pastes with optimal inorganic fillers and a ball-milling method. We carefully controlled the ball-milling sequence and time to avoid any damage to the CNTs, which incorporated fillers that were fully dispersed as paste constituents. The field electron emitters fabricated by printing the CNT pastes were found to exhibit almost perfect adhesion of the CNT emitters to the cathode, along with good uniformity and reproducibility. A high field enhancement factor of around 10,000 was achieved from the CNT field emitters developed. By selecting nano-sized metal alloys and oxides and using the same formulation sequence, we also developed reliable field emitters that could survive high-temperature post processing. These field emitters had high durability to post vacuum annealing at 950 °C, guaranteeing survival of the brazing process used in the sealing of field emission x-ray tubes. We evaluated the field emitters in a triode configuration in the harsh environment of a tiny vacuum-sealed vessel and observed very reliable operation for 30 h at a high current density of 350 mA cm(-2). The CNT pastes and related field emitters that were developed could be usefully applied in reliable field emission devices.
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NASA Astrophysics Data System (ADS)
Kim, Jae-Woo; Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho
2014-02-01
Highly reliable field electron emitters were developed using a formulation for reproducible damage-free carbon nanotube (CNT) composite pastes with optimal inorganic fillers and a ball-milling method. We carefully controlled the ball-milling sequence and time to avoid any damage to the CNTs, which incorporated fillers that were fully dispersed as paste constituents. The field electron emitters fabricated by printing the CNT pastes were found to exhibit almost perfect adhesion of the CNT emitters to the cathode, along with good uniformity and reproducibility. A high field enhancement factor of around 10 000 was achieved from the CNT field emitters developed. By selecting nano-sized metal alloys and oxides and using the same formulation sequence, we also developed reliable field emitters that could survive high-temperature post processing. These field emitters had high durability to post vacuum annealing at 950 °C, guaranteeing survival of the brazing process used in the sealing of field emission x-ray tubes. We evaluated the field emitters in a triode configuration in the harsh environment of a tiny vacuum-sealed vessel and observed very reliable operation for 30 h at a high current density of 350 mA cm-2. The CNT pastes and related field emitters that were developed could be usefully applied in reliable field emission devices.
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Thinning and opening of carbon nanotubes by oxidation using carbon dioxide
NASA Astrophysics Data System (ADS)
Tsang, S. C.; Harris, P. J. F.; Green, M. L. H.
1993-04-01
THE discovery1 and bulk synthesis2 of carbon nanotubes has stimulated great interest. It has been suggested that these structures may have useful electronic3-5 and mechanical6 properties, and these might be modified by introducing foreign materials into the nanotubes. But the tubes are invariably capped at the ends. Ajayan and lijima7 have succeeded in drawing molten material (lead or one of its compounds) into the tubes by heating them in the presence of lead and oxygen; less than 1% of the tubes in the sample studied could be filled in this way. Here we report that heating in carbon dioxide gas can result in the partial or complete destruction of the tube caps and stripping of the outer layers to produce thinner tubes. In some cases, we have thinned the extremity of tubes to a single layer. The opened tubes can be regarded as nanoscale test-tubes for adsorption of other molecules, and this controlled method of thinning may allow studies of the properties of single tubes.
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ERIC Educational Resources Information Center
Kim, Hy
1985-01-01
A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show bubbles released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected gas; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-13
... Pipe and Tube From Turkey: Notice of Extension of Time Limit for Final Results of Antidumping Duty... antidumping order on certain welded carbon steel pipe and tube from Turkey for the period May 1, 2009, through April 30, 2010. See Certain Welded Carbon Steel Pipe and Tube From Turkey; Notice of Preliminary Results...
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Method for producing carbon nanotubes
Phillips, Jonathan [Santa Fe, NM; Perry, William L [Jemez Springs, NM; Chen, Chun-Ku [Albuquerque, NM
2006-02-14
Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.
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Preparation of nitrogen-doped carbon tubes
Chung, Hoon Taek; Zelenay, Piotr
2015-12-22
A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.
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Liu, Kai; Zhu, Feng; Liu, Liang; Sun, Yinghui; Fan, Shoushan; Jiang, Kaili
2012-06-07
Defects of carbon nanotubes, weak tube-tube interactions, and weak carbon nanotube joints are bottlenecks for obtaining high-strength carbon nanotube yarns. Some solution processes are usually required to overcome these drawbacks. Here we fabricate ultra-long and densely packed pure carbon nanotube yarns by a two-rotator twisting setup with the aid of some tensioning rods. The densely packed structure enhances the tube-tube interactions, thus making high tensile strengths of carbon nanotube yarns up to 1.6 GPa. We further use a sweeping laser to thermally treat as-produced yarns for recovering defects of carbon nanotubes and possibly welding carbon nanotube joints, which improves their Young's modulus by up to ∼70%. The spinning and laser sweeping processes are solution-free and capable of being assembled together to produce high-strength yarns continuously as desired.
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NASA Technical Reports Server (NTRS)
Misencik, J. A.
1982-01-01
Alloy tubes filled with hydrogen doped with various amounts of carbon monoxide, carbon dioxide, ethane, ethylene, methane, ammonia, or water were heated in a diesel fuel-fired Stirling engine simulator materials test rig for 100 hours at 21 MPa and 760 or 820 C to determine the effectiveness of the dopants in reducing hydrogen permeation through the hot tube walls. Ultra high purity (UHP) hydrogen was used for comparison. The tube alloys were N-155, A-286, Incoloy 800, Nitronic 40, 19-9DL, 316 stainless steel, Inconel 718, and HS-188. Carbon dioxide and carbon monoxide in the concentration range 0.2 to 5 vol % were most effective in reducing hydrogen permeation through the hot tube walls for all alloys. Ethane, ethylene, methane, ammonia, and water at the concentrations investigated were not effective in reducing the permeation below that achieved with UHP hydrogen. One series of tests were conducted with UHP hydrogen in carburized tubes. Carburization of the tubes prior to exposure reduced permeation to values similar to those for carbon monoxide; however, carbon dioxide was the most effective dopant.
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Electroacoustic control of Rijke tube instability
NASA Astrophysics Data System (ADS)
Zhang, Yumin; Huang, Lixi
2017-11-01
Unsteady heat release coupled with pressure fluctuation triggers the thermoacoustic instability which may damage a combustion chamber severely. This study demonstrates an electroacoustic control approach of suppressing the thermoacoustic instability in a Rijke tube by altering the wall boundary condition. An electrically shunted loudspeaker driver device is connected as a side-branch to the main tube via a small aperture. Tests in an impedance tube show that this device has sound absorption coefficient up to 40% under normal incidence from 100 Hz to 400 Hz, namely over two octaves. Experimental result demonstrates that such a broadband acoustic performance can effectively eliminate the Rijke-tube instability from 94 Hz to 378 Hz (when the tube length varies from 1.8 m to 0.9 m, the first mode frequency for the former is 94 Hz and the second mode frequency for the latter is 378 Hz). Theoretical investigation reveals that the devices act as a damper draining out sound energy through a tiny hole to eliminate the instability. Finally, it is also estimated based on the experimental data that small amount of sound energy is actually absorbed when the system undergoes a transition from the unstable to stable state if the contrpaol is activated. When the system is actually stabilized, no sound is radiated so no sound energy needs to be absorbed by the control device.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-06-07
... Pipe and Tube Products From Turkey: Preliminary Results of Antidumping Duty Administrative Review; 2011... tube products (welded pipe and tube) from Turkey.\\2\\ The period of review is May 1, 2011, to April 30... order. See Antidumping Duty Order; Welded Carbon Steel Standard Pipe and Tube Products from Turkey, 51...
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Fabrication of TiNi/CFRP smart composite using cold drawn TiNi wires
NASA Astrophysics Data System (ADS)
Xu, Ya; Otsuka, Kazuhiro; Toyama, Nobuyuki; Yoshida, Hitoshi; Jang, Byung-Koog; Nagai, Hideki; Oishi, Ryutaro; Kishi, Teruo
2002-07-01
In recent years, pre-strained TiNi shape memory alloys (SMA) have been used for fabricating smart structure with carbon fibers reinforced plastics (CFRP) in order to suppress microscopic mechanical damages. However, since the cure temperature of CFRP is higher than the reverse transformation temperatures of TiNi SMA, special fixture jigs have to be used for keeping the pre-strain during fabrication, which restricted its practical application. In order to overcome this difficulty, we developed a new method to fabricate SMA/CFRP smart composites without using special fixture jigs by controlling the transformation temperatures of SMA during fabrication. This method consists of using heavily cold-worked wires to increase the reverse transformation temperatures, and of using flash electrical heating of the wires after fabrication in order to decrease the reverse transformation temperatures to a lower temperature range again without damaging the epoxy resin around SMA wires. By choosing proper cold-working rate and composition of TiNi alloys, the reverse transformation temperatures were well controlled, and the TiNi/CFRP hybrid smart composite was fabricated without using special fixture jigs. The damage suppressing effect of cold drawn wires embedded in CFRP was confirmed.
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Auto-fusion and the shaping of neurons and tubes
Soulavie, Fabien; Sundaram, Meera V.
2016-01-01
Cells adopt specific shapes that are necessary for specific functions. For example, some neurons extend elaborate arborized dendrites that can contact multiple targets. Epithelial and endothelial cells can form tiny seamless unicellular tubes with an intracellular lumen. Recent advances showed that cells can auto-fuse to acquire those specific shapes. During auto-fusion, a cell merges two parts of its own plasma membrane. In contrast to cell-cell fusion or macropinocytic fission, which result in the merging or formation of two separate membrane bound compartments, auto-fusion preserves one compartment, but changes its shape. The discovery of auto-fusion in C. elegans was enabled by identification of specific protein fusogens, EFF-1 and AFF-1, that mediate cell-cell fusion. Phenotypic characterization of eff-1 and aff-1 mutants revealed that fusogen-mediated fusion of two parts of the same cell can be used to sculpt dendritic arbors, reconnect two parts of an axon after injury, or form a hollow unicellular tube. Similar auto-fusion events recently were detected in vertebrate cells, suggesting that auto-fusion could be a widely used mechanism for shaping neurons and tubes. PMID:27436685
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Jeličić, Aleksandra; Friedrich, Alwin; Jeremić, Katarina; Siekmeyer, Gerd; Taubert, Andreas
2009-01-01
One of the main issues with the use of nickel titanium alloy (NiTi) implants in cardiovascular implants (stents) is that these devices must be of very high quality in order to avoid subsequent operations due to failing stents. For small stents with diameters below ca. 2 mm, however, stent characterization is not straightforward. One of the main problems is that there are virtually no methods to characterize the interior of the NiTi tubes used for fabrication of these tiny stents. The current paper reports on a robust hybrid actuator for the characterization of NiTi tubes prior to stent fabrication. The method is based on a polymer/hydrogel/magnetic nanoparticle hybrid material and allows for the determination of the inner diameter at virtually all places in the raw NiTi tubes. Knowledge of the inner structure of the raw NiTi tubes is crucial to avoid regions that are not hollow or regions that are likely to fail due to defects inside the raw tube. The actuator enables close contact of a magnetic polymer film with the inner NiTi tube surface. The magnetic signal can be detected from outside and be used for a direct mapping of the tube interior. As a result, it is possible to detect critical regions prior to expensive and slow stent fabrication processes.
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Mangla, Yash; Tandon, Rajesh; Goel, Shailendra; Raina, S. N.
2013-01-01
Closure of carpels or angiospermy, a key developmental innovation, has been accomplished through different ontogenic routes among the flowering plants. The mechanism of angiospermy produces structural novelties in the gynoecium, which in turn affects the progamic phase. In this paper, we present the structural details of the gynoecium and functional attributes of the progamic phase of Hippophae rhamnoides, a dioecious species of Elaeagnaceae. The gynoecium is unicarpellate, and the carpel is dorsiventrally symmetric and conduplicate. The pollen tube path comprises a prominent, ventrally localized dry and non-papillate stigma, a pseudostyle and a dorsally protruded superior ovary. The pollen tube path in the stigmatic region is subdermal, and from the pseudostyle onwards, it resides over the epidermis of conduplicated margins. The epidermal cells along this region are secretory but produce sparse extracellular matrix. The tube approaches the solitary ovule through a tiny conduit in the carpel, the ventral pore. The duration of the entire progamic phase is ∼72 h. The observed mean pollen tube length from stigma to ovule was 908.13 ± 180 µm and the mean tube growth rate was 18.75 µm h−1. The study demonstrates that sea buckthorn, a core eudicot, has a simple gynoecium with a pollen tube pathway that incorporates elements of both completely externalized and internalized compitum.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-12-31
... Pipe and Tube Products From Turkey: Final Results of Antidumping Duty Administrative Review; 2011-2012... pipe and tube products (welded pipe and tube) from Turkey.\\1\\ The period of review (POR) is May 1, 2011... during the POR.\\2\\ \\1\\ See Welded Carbon Steel Standard Pipe and Tube Products from Turkey: Preliminary...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-06-28
... Pipes and Tubes From Thailand: Rescission of Antidumping Duty Administrative Review AGENCY: Import... tubes from Thailand. See Antidumping or Countervailing Duty Order, Finding, or Suspended Investigation... the antidumping duty order on circular welded carbon steel pipes and tubes from Thailand for the...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-01-18
... DEPARTMENT OF COMMERCE International Trade Administration [A-489-501] Certain Welded Carbon Steel Pipe and Tube From Turkey: Extension of Time Limit for Preliminary Results of Antidumping Duty... certain welded carbon steel pipe and tube from Turkey covering the period May 1, 2010, through April 30...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-19
... DEPARTMENT OF COMMERCE International Trade Administration [A-489-501] Certain Welded Carbon Steel Pipe and Tube From Turkey: Extension of Time Limit for Preliminary Results of Antidumping Duty... welded carbon steel pipe and tube from Turkey covering the period May 1, 2009, through April 30, 2010...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-20
... Standard Pipe and Tube From Turkey: Intent To Rescind Countervailing Duty Administrative Review, in Part... certain welded carbon steel pipe and tube from Turkey. See Antidumping or Countervailing Duty Order... Certain Welded Carbon Steel Standard Pipe from Turkey,'' (October 27, 2011). A Type 3 entry is an entry of...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-25
... DEPARTMENT OF COMMERCE International Trade Administration [A-489-501] Certain Welded Carbon Steel Pipe and Tube from Turkey: Extension of Time Limit for Preliminary Results of Antidumping Duty... antidumping duty order on certain welded carbon steel pipe and tube from Turkey covering the period May 1...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-02-08
... Standard Pipe and Tube From Turkey: Notice of Final Rescission of Countervailing Duty Administrative Review...) order on certain welded carbon steel pipe and tube from Turkey for the period of review (POR) of January... of Certain Welded Carbon Steel Standard Pipe from Turkey,'' (October 27, 2011). We reviewed the...
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Ceramic pore channels with inducted carbon nanotubes for removing oil from water.
Chen, Xinwei; Hong, Liang; Xu, Yanfang; Ong, Zheng Wei
2012-04-01
Water contaminated with tiny oil emulsions is costly and difficult to treat because of the colloidal stability and deformable nature of emulsified oil. This work utilizes carbon nanotubes (CNTs) in macro/mesopore channels of ceramic membrane to remove tiny oil droplets from water. The CNTs were implanted into the porous ceramic channels by means of chemical vapor deposition. Being hydrophobic in nature and possessing an interfacial curvature at nanoscale, CNTs enabled tiny oil emulsion in submicrometer and nano scales to be entrapped while permeating through the CNTs implanted pore channels. Optimizing the growth condition of the CNTs resulted in a uniform distribution of CNT grids, which allowed the development of lipophilic layers during filtration. These lipo-layers drastically enhanced the separation performance. The filtration capability of CNT-ceramic membrane was assessed by the purification of a dilute oil-in-water (o/w) emulsion containing ca. 210 ppm mineral oil 1600 ppm emulsifier, and a trace amount of dye, a proxy polluted water source. The best CNT-tailored ceramic membrane, prepared under the optimized CNT growth condition, claimed 100% oil rejection rate and a permeation flux of 0.6 L m(-2) min(-1), driven by a pressure drop of ca. 1 bar for 3 days on the basis of UV measurement. The CNT-sustained adsorption complements the size-exclusion mechanism in removing soluble oil.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-12-23
... tubing, of iron (other than cast iron) or steel (both carbon and alloy), whether seamless or welded... and tubing, of iron (other than cast iron) or steel (both carbon and alloy), whether seamless or..., United States Steel Corporation, Boomerang Tube, Energex Tube, a division of JMC Steel Group, Northwest...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-28
... Pipes and Tubes From Thailand: Final Results of Antidumping Duty New Shipper Review AGENCY: Import... Thailand. See Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results of... review under the antidumping duty order covering pipes and tubes from Thailand. See Preliminary Results...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-12-06
... Pipes and Tubes From Turkey; Final Results of Antidumping Duty Administrative Review; 2010 to 2011... tubes from Turkey.\\1\\ This review covers four producers and exporters of subject merchandise: Borusan....'' \\1\\ See Circular Welded Carbon Steel Pipes and Tubes From Turkey: Notice of Preliminary Results of...
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Integrated structure vacuum tube
NASA Technical Reports Server (NTRS)
Dimeff, J.; Kerwin, W. J. (Inventor)
1976-01-01
High efficiency, multi-dimensional thin film vacuum tubes suitable for use in high temperature, high radiation environments are described. The tubes are fabricated by placing thin film electrode members in selected arrays on facing interior wall surfaces of an alumina substrate envelope. Cathode members are formed using thin films of triple carbonate. The photoresist used in photolithography aids in activation of the cathodes by carbonizing and reacting with the reduced carbonates when heated in vacuum during forming. The finely powdered triple carbonate is mixed with the photoresist used to delineate the cathode locations in the conventional solid state photolithographic manner. Anode and grid members are formed using thin films of refractory metal. Electron flow in the tubes is between grid elements from cathode to anode as in a conventional three-dimensional tube.
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Visualization of bacteriophage P1 infection by cryo-electron tomography of tiny Escherichia coli
DOE Office of Scientific and Technical Information (OSTI.GOV)
Liu Jun, E-mail: Jun.Liu.1@uth.tmc.edu; Chen Chengyen; Shiomi, Daisuke
2011-09-01
Bacteriophage P1 has a contractile tail that targets the conserved lipopolysaccharide on the outer membrane surface of the host for initial adsorption. The mechanism by which P1 DNA enters the host cell is not well understood, mainly because the transient molecular interactions between bacteriophage and bacteria have been difficult to study by conventional approaches. Here, we engineered tiny E. coli host cells so that the initial stages of P1-host interactions could be captured in unprecedented detail by cryo-electron tomography. Analysis of three-dimensional reconstructions of frozen-hydrated specimens revealed three predominant configurations: an extended tail stage with DNA present in the phagemore » head, a contracted tail stage with DNA, and a contracted tail stage without DNA. Comparative analysis of various conformations indicated that there is uniform penetration of the inner tail tube into the E. coli periplasm and a significant movement of the baseplate away from the outer membrane during tail contraction.« less
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-05-13
... Pipes and Tubes From Thailand: Amended Final Results of Antidumping Duty Administrative Review Pursuant... tubes from Thailand, which covered Saha Thai Steel Pipe (Public) Co., Ltd. (Saha Thai) and the period March 1, 2006, through February 28, 2007. See Circular Welded Carbon Steel Pipes and Tubes from Thailand...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-10-31
... Pipes and Tubes From Thailand: Final Results of Antidumping Duty Administrative Review; 2011-2012 AGENCY... and tubes from Thailand. This review covers two producers and/or exporters of the subject merchandise... duty order on circular welded carbon steel pipes and tubes from Thailand.\\1\\ We invited interested...
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75 FR 16655 - Airworthiness Directives; Rolls-Royce plc RB211-Trent 700 Series Turbofan Engines
Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-02
... pressure (HP-IP) turbine internal and external oil vent tubes for coking and carbon buildup, and cleaning... borescope inspections of the HP-IP turbine internal and external oil vent tubes for coking and carbon...-intermediate pressure (HP-IP) turbine internal oil vent tubes, external oil vent tubes, and bearing chamber...
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Urban, Jeff
Berkeley Lab materials scientist, Jeff Urban presents his research on using metal-organic frameworks to capture carbon at Berkeley Lab's Cleantech Pitchfest on June 1, 2016. Removing excess carbon from an overheating atmosphere is an urgent and complicated problem. The answer, according to Berkeley Lab’s Jeff Urban, could lie at the nanoscale, where specially designed cage-like structures called metal organic frameworks, or MOFs, can trap large amounts of carbon in microscopically tiny structures. A Harvard PhD with expertise in thermoelectrics, gas separation and hydrogen storage, Urban directs teams at the Molecular Foundry’s Inorganic Materials Facility.
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A novel quick transendoscopic enteral tubing in mid-gut: technique and training with video.
Long, Chuyan; Yu, Yan; Cui, Bota; Jagessar, Sabreen Abdul Rahman; Zhang, Jie; Ji, Guozhong; Huang, Guangming; Zhang, Faming
2018-03-13
This study aimed to evaluate the feasibility, safety, and value of a quick technique for transendoscopic enteral tubing (TET) through mid-gut. A prospective interventional study was performed in a single center. A TET tube was inserted into mid-gut through the nasal orifice and fixed on the pylorus wall by one tiny titanium endoscopic clip under anesthesia. The feasibility, safety, success rate, and satisfaction with TET placement were evaluated for enteral nutrition or fecal microbiota transplantation. A total of 86 patients underwent mid-gut TET. The success rate of the TET procedure was 98.8% (85/86). Mean tubing time of the TET procedure was 4.2 ± 1.9 min. 10 cases of procedure was enough for training of general endoscopist to shorten the procedure time (7.0 min vs 4.0 min, p < 0.05). 97.7% (84/86) of patients were satisfied with the TET placement. Procedure-related and tube-related adverse events were observed in 8.1% (7/86) and 7.0% (6/86) of patients respectively. There were no moderate to severe adverse events during tube extubation. TET through mid-gut is a novel, convenient, reliable and safe procedure for mid-gut administration with a high degree of patient satisfaction. This research was retrospectively registered with clinicaltrials.gov. Trial registration date: 29th November 2017. NCT03335982 .
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A vacuum-sealed miniature X-ray tube based on carbon nanotube field emitters
NASA Astrophysics Data System (ADS)
Heo, Sung Hwan; Kim, Hyun Jin; Ha, Jun Mok; Cho, Sung Oh
2012-05-01
A vacuum-sealed miniature X-ray tube based on a carbon nanotube field-emission electron source has been demonstrated. The diameter of the X-ray tube is 10 mm; the total length of the tube is 50 mm, and no external vacuum pump is required for the operation. The maximum tube voltage reaches up to 70 kV, and the X-ray tube generates intense X-rays with the air kerma strength of 108 Gy·cm2 min-1. In addition, X-rays produced from the miniature X-ray tube have a comparatively uniform spatial dose distribution.
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NASA Technical Reports Server (NTRS)
Maiti, Amitesh; Svizhenko, Alexei; Anantram, M. P.; Biegel, Bryan (Technical Monitor)
2001-01-01
Atomistic simulations using a combination of classical force field and Density-Functional-Theory (DFT) show that carbon atoms remain essentially sp2 coordinated in either bent tubes or tubes pushed by an atomically sharp AFM tip. Subsequent Green's-function-based transport calculations reveal that for armchair tubes there is no significant drop in conductance, while for zigzag tubes the conductance can drop by several orders of magnitude in AFM-pushed tubes. The effect can be attributed to simple stretching of the tube under tip deformation, which opens up an energy gap at the Fermi surface.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-08
... DEPARTMENT OF COMMERCE International Trade Administration [A-583-008] Circular Welded Carbon Steel... antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan. See Preliminary Results of Antidumping Duty Administrative Review: Circular Welded Carbon Steel [[Page 62367
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Auto-fusion and the shaping of neurons and tubes.
Soulavie, Fabien; Sundaram, Meera V
2016-12-01
Cells adopt specific shapes that are necessary for specific functions. For example, some neurons extend elaborate arborized dendrites that can contact multiple targets. Epithelial and endothelial cells can form tiny seamless unicellular tubes with an intracellular lumen. Recent advances showed that cells can auto-fuse to acquire those specific shapes. During auto-fusion, a cell merges two parts of its own plasma membrane. In contrast to cell-cell fusion or macropinocytic fission, which result in the merging or formation of two separate membrane bound compartments, auto-fusion preserves one compartment, but changes its shape. The discovery of auto-fusion in C. elegans was enabled by identification of specific protein fusogens, EFF-1 and AFF-1, that mediate cell-cell fusion. Phenotypic characterization of eff-1 and aff-1 mutants revealed that fusogen-mediated fusion of two parts of the same cell can be used to sculpt dendritic arbors, reconnect two parts of an axon after injury, or form a hollow unicellular tube. Similar auto-fusion events recently were detected in vertebrate cells, suggesting that auto-fusion could be a widely used mechanism for shaping neurons and tubes. Copyright © 2016 Elsevier Ltd. All rights reserved.
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SF Cleantech Pitchfest: Nano Sponges for Carbon Capture
Urban, Jeff
2018-01-16
Berkeley Lab materials scientist, Jeff Urban presents his research on using metal-organic frameworks to capture carbon at Berkeley Lab's Cleantech Pitchfest on June 1, 2016. Removing excess carbon from an overheating atmosphere is an urgent and complicated problem. The answer, according to Berkeley Labâs Jeff Urban, could lie at the nanoscale, where specially designed cage-like structures called metal organic frameworks, or MOFs, can trap large amounts of carbon in microscopically tiny structures. A Harvard PhD with expertise in thermoelectrics, gas separation and hydrogen storage, Urban directs teams at the Molecular Foundryâs Inorganic Materials Facility.
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Cardoso, Silvana S S; Cartwright, Julyan H E; Checa, Antonio G; Sainz-Díaz, C Ignacio
2016-10-01
We show with laboratory experiments that self-assembled mineral tube formation involving precipitation around a templating jet of fluid - a mechanism well-known in the physical sciences from the tubular growth of so-called chemical gardens - functions with carbonates, and we analyse the microstructures and compositions of the precipitates. We propose that there should exist biological examples of fluid-flow-templated tubes formed from carbonates. We present observational and theoretical modelling evidence that the complex structure of biomineral calcium carbonate tubules that forms the 'rose' of the watering-pot shells, Clavagelloidea, may be an instance of this mechanism in biomineralization. We suggest that this is an example of self-organization and self-assembly processes in biomineralization, and that such a mechanism is of interest for the production of tubes as a synthetic biomaterial. The work discussed in the manuscript concerns the self-assembly of calcium carbonate micro-tubes and nano-tubes under conditions of fluid flow together with chemical reaction. We present the results of laboratory experiments on tube self-assembly together with theoretical calculations. We show how nature may already be making use of this process in molluscan biomineralization of the so-called watering-pot shells, and we propose that we may be able to take advantage of the formation mechanism to produce synthetic biocompatible micro- and nano-tubes. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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Khalili, Vida; Khalil-Allafi, Jafar; Sengstock, Christina; Motemani, Yahya; Paulsen, Alexander; Frenzel, Jan; Eggeler, Gunther; Köller, Manfred
2016-06-01
Release of Ni(1+) ions from NiTi alloy into tissue environment, biological response on the surface of NiTi and the allergic reaction of atopic people towards Ni are challengeable issues for biomedical application. In this study, composite coatings of hydroxyapatite-silicon multi walled carbon nano-tubes with 20wt% Silicon and 1wt% multi walled carbon nano-tubes of HA were deposited on a NiTi substrate using electrophoretic methods. The SEM images of coated samples exhibit a continuous and compact morphology for hydroxyapatite-silicon and hydroxyapatite-silicon-multi walled carbon nano-tubes coatings. Nano-indentation analysis on different locations of coatings represents the highest elastic modulus (45.8GPa) for HA-Si-MWCNTs which is between the elastic modulus of NiTi substrate (66.5GPa) and bone tissue (≈30GPa). This results in decrease of stress gradient on coating-substrate-bone interfaces during performance. The results of nano-scratch analysis show the highest critical distance of delamination (2.5mm) and normal load before failure (837mN) as well as highest critical contact pressure for hydroxyapatite-silicon-multi walled carbon nano-tubes coating. The cell culture results show that human mesenchymal stem cells are able to adhere and proliferate on the pure hydroxyapatite and composite coatings. The presence of both silicon and multi walled carbon nano-tubes (CS3) in the hydroxyapatite coating induce more adherence of viable human mesenchymal stem cells in contrast to the HA coated samples with only silicon (CS2). These results make hydroxyapatite-silicon-multi walled carbon nano-tubes a promising composite coating for future bone implant application. Copyright © 2016 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Yang, Dong
Failure of carbon steel boiler tubes from waterside has been reported in the utility boilers and industrial boilers for a long time. In industrial boilers, most waterside tube cracks are found near heavy attachment welds on the outer surface and are typically blunt, with multiple bulbous features indicating a discontinuous growth. These types of tube failures are typically referred to as stress assisted corrosion (SAC). For recovery boilers in the pulp and paper industry, these failures are particularly important as any water leak inside the furnace can potentially lead to smelt-water explosion. Metal properties, environmental variables, and stress conditions are the major factors influencing SAC crack initation and propagation in carbon steel boiler tubes. Slow strain rate tests (SSRT) were conducted under boiler water conditions to study the effect of temperature, oxygen level, and stress conditions on crack initation and propagation on SA-210 carbon steel samples machined out of boiler tubes. Heat treatments were also performed to develop various grain size and carbon content on carbon steel samples, and SSRTs were conducted on these samples to examine the effect of microstructure features on SAC cracking. Mechanisms of SAC crack initation and propagation were proposed and validated based on interrupted slow strain tests (ISSRT). Water chemistry guidelines are provided to prevent SAC and fracture mechanics model is developed to predict SAC failure on industrial boiler tubes.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-11-21
... DEPARTMENT OF COMMERCE International Trade Administration [A-549-502] Circular Welded Carbon Steel Pipes and Tubes From Thailand: Extension of Time Limit for Preliminary Results of Antidumping Duty... and tubes from Thailand for the period March 1, 2010, through February 28, 2011. See Initiation of...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-11-29
... Pipes and Tubes from Thailand: Amended Final Results of Antidumping Duty Administrative Review AGENCY... Thailand, covering the period March 1, 2008 through February 28, 2009. The final results were subsequently... Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-14
... Pipes and Tubes From Taiwan: Final Results of Antidumping Duty Administrative Review AGENCY: Import... Department of Commerce (the Department) published the preliminary results of the administrative review of the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan. See Preliminary Results of...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-22
...) (Preliminary Determination). On June 12, 2012, respondent Universal Tube and Plastic Industries, Ltd. (UTP-JA... Universal Tube and Plastic Industries, Ltd. in the Antidumping Duty Investigation of Circular Welded Carbon... Verification of Universal Tube and Plastic Industries, Ltd. (UTP-JA) and Its Home Market Affiliates...
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Experimental Studies of Carbon Nanotube Materials for Space Radiators
NASA Technical Reports Server (NTRS)
SanSoucie, MIchael P.; Rogers, Jan R.; Craven, Paul D.; Hyers, Robert W.
2012-01-01
Game ]changing propulsion systems are often enabled by novel designs using advanced materials. Radiator performance dictates power output for nuclear electric propulsion (NEP) systems. Carbon nanotubes (CNT) and carbon fiber materials have the potential to offer significant improvements in thermal conductivity and mass properties. A test apparatus was developed to test advanced radiator designs. This test apparatus uses a resistance heater inside a graphite tube. Metallic tubes can be slipped over the graphite tube to simulate a heat pipe. Several sub ]scale test articles were fabricated using CNT cloth and pitch ]based carbon fibers, which were bonded to a metallic tube using an active braze material. The test articles were heated up to 600 C and an infrared (IR) camera captured the results. The test apparatus and experimental results are presented here.
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A Materials Compatibility and Thermal Stability Analysis of Common Hydrocarbon Fuels
NASA Technical Reports Server (NTRS)
Meyer, M. L.; Stiegemeier, B. R.
2005-01-01
A materials compatibility and thermal stability investigation was conducted using five common liquid hydrocarbon fuels and two structural materials. The tests were performed at the NASA Glenn Research Center Heated Tube Facility under environmental conditions similar to those encountered in regeneratively cooled rocket engines. Scanning-electron microscopic analysis in conjunction with energy dispersive spectroscopy (EDS) was utilized to characterize the condition of the tube inner wall surface and any carbon deposition or corrosion that was formed during selected runs. Results show that the carbon deposition process in stainless steel tubes was relatively insensitive to fuel type or test condition. The deposition rates were comparable for all fuels and none of the stainless steel test pieces showed any signs of corrosion. For tests conducted with copper tubing, the sulfur content of the fuel had a significant impact on both the condition of the tube wall and carbon deposition rates. Carbon deposition rates for the lowest sulfur fuels (2 ppm) were slightly higher than those recorded in the stainless steel tubes with no corrosion observed on the inner wall surface. For slightly higher sulfur content (25 ppm) fuels, nodules that intruded into the flow area were observed to form on the inner wall surface. These nodules induced moderate tube pressure drop increases. The highest sulfur content fuels (400 ppm) produced extensive wall pitting and dendritic copper sulfide growth that was continuous along the entire tube wall surface. The result of this tube degradation was the inability to maintain flow rate due to rapidly increasing test section pressure drops. Accompanying this corrosion were carbon deposition rates an order of magnitude greater than those observed in comparable stainless steel tests. The results of this investigation indicate that trace impurities in fuels (i.e. sulfur) can significantly impact the carbon deposition process and produce unacceptable corrosion levels in copper based structural materials.
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Innovative Energy Absorbing Mounting Systems for High Mass Rotorcraft Payloads
2008-12-01
that a maximum SEA value of 21.5 J/g can be achieved with a ±45° FMC tube and an aramid/ phenolic hexagonal honeycomb core with a crush stress of 10...Table 3. Optimized TTSRD tube SEA values (J/g) for various tube material systems. Carbon FMC Carbon/ Epoxy E-Glass/ Epoxy Kevlar / Epoxy Max...material systems considered in the present study, the crush tube concept had a maximum SEA of 21.5 J/g with a ±45° FMC tube and an aramid/ phenolic
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Apparatus for producing diamond-like carbon flakes
NASA Technical Reports Server (NTRS)
Banks, Bruce A. (Inventor)
1986-01-01
A vacuum arc from a spot at the face of a graphite cathode to a graphite anode produces a beam of carbon ions and atoms. A carbon coating from this beam is deposited on an ion beam sputtered target to produce diamond-like carbon flakes. A graphite tube encloses the cathode, and electrical isolation is provided by an insulating sleeve. The tube forces the vacuum arc spot to be confined to the surface on the outermost end of the cathode. Without the tube the arc spot will wander to the side of the cathode. This spot movement results in low rates of carbon deposition, and the properties of the deposited flakes are more graphite-like than diamond-like.
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Wintering bats of the upper Snake River Plain: occurrence in lava-tube caves
DOE Office of Scientific and Technical Information (OSTI.GOV)
Genter, D.L.
Distribution and habitat selection of hibernating bats at the Idaho National Engineering Laboratory (INEL) and adjacent area are reported. Exploration of over 30 lava-tube caves revealed that two species, Myotis leibii and Plecotus townsendii, hibernate in the upper Snake River Plain. Five species, M. lucifugus, M. evotis, Eptesicus fuscus, Lasionycteris noctivagans, and Lasiurus cinereus are considered migratory. Myotis leibii and P. townsendii hibernate throughout much of the area, occasionally in mixed-species groups. Myotis leibii uses the dark and protected regions of the cave, usually wedged into tiny pockets and crevices near or at the highest portion of the ceiling. Individualsmore » of P. townsendii may be found at any height or depth in the cave. Temperature appears to be primary limiting factor in habitat selection. Myotis leibii was found in significantly cooler air temperatures than P. townsendii. Neither species tolerated continuous temperatures below 1.5 C. Relative humidity does not seem to be a significant factor in the distribution or habitat selection of the two species in lava-tube caves. 18 references, 1 figure, 1 table.« less
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Modeling the kinetics of bubble nucleation in champagne and carbonated beverages.
Liger-Belair, Gérard; Parmentier, Maryline; Jeandet, Philippe
2006-10-26
In champagne and carbonated beverages, bubble nucleation was mostly found to take place from tiny Taylor-like bubbles trapped inside immersed cellulose fibers stuck on the glass wall. The present paper complements a previous paper about the thorough examination of the bubble nucleation process in a flute poured with champagne (Liger-Belair et al. J. Phys. Chem. B 2005, 109, 14573). In this previous paper, a model was built that accurately reproduces the dynamics of these tiny Taylor-like bubbles that grow inside the fiber's lumen by diffusion of CO(2)-dissolved molecules. In the present paper, by use of the model recently developed, the frequency of bubble formation from cellulose fibers is accessed and linked with various liquid and fiber parameters, namely, the concentration c(L) of CO(2)-dissolved molecules, the liquid temperature theta, its viscosity eta, the ambient pressure P, the course of the gas pocket growing trapped inside the fiber's lumen before releasing a bubble, and the radius r of the fiber's lumen. The relative influence of the latter parameters on the bubbling frequency is discussed and supported with recent experimental observations and data.
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Noise characteristics of single-walled carbon nanotube network transistors.
Kim, Un Jeong; Kim, Kang Hyun; Kim, Kyu Tae; Min, Yo-Sep; Park, Wanjun
2008-07-16
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.
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Ishizaki, M
1978-03-01
A method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer is described. The sample is burned by an oxygen-flask combustion procedure, the resulting solution is treated with a cation-exchange resin to eliminate interfering cations, the selenium is extracted with dithizone in carbon tetrachloride and the resulting selenium dithizonate is combined with nickel nitrate in the carbon tube to enhance the sensitivity for selenium and avoid volatilization losses. The method measures selenium concentrations as low as 0.01 mug/g with a relative standard deviation of 8%.
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Noise And Charge Transport In Carbon Nanotube Devices
NASA Astrophysics Data System (ADS)
Reza, Shahed; Huynh, Quyen T.; Bosman, Gijs; Sippel, Jennifer; Rinzler, Andrew G.
2005-11-01
The charge transport and noise properties of three terminal, gated devices containing multiple, single wall, metallic and semiconductor carbon nanotubes have been measured as a function of gate and drain bias at 300K. Using pulsed bias the metallic tubes could be burned sequentially enabling the separation of measured conductance and low frequency excess noise into metallic and semiconductor contributions. The relative low frequency excess noise of the metallic tubes was about a factor 100 lower than that of the semiconductor tubes, whereas the conductance of the metallic tubes was significantly higher (10 to 50 times) than that of the semiconductor tubes.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-15
... DEPARTMENT OF COMMERCE International Trade Administration [A-533-502] Certain Welded Carbon Steel... or (202) 482-1690, respectively. SUPPLEMENTARY INFORMATION: Background On June 14, 2010, the... antidumping duty order on certain welded carbon steel standard pipes and tubes from India. See Certain Welded...
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Mordiffi, Siti Zubaidah; Goh, Mien Li; Phua, Jason; Chan, Yiong-Huak
2016-09-01
The effect of delivering enteral nutrition or medications via a nasogastric tube that is inadvertently located in the tracheobronchial tract can cause respiratory complications. Although radiographic examination is accepted as the gold standard for confirming the position of patients' enteral tubes, it is costly, involves risks of radiation, and is not failsafe. Studies using carbon dioxide sensors to detect inadvertent nasogastric tube placements have been conducted in intensive care settings. However, none involved patients in general wards. The objective of this study was to ascertain the diagnostic measure of colorimeter, with radiographic examination as the reference standard, to confirm the location of nasogastric tubes in patients. A prospective observational study of a diagnostic test. This study was conducted in the general wards of an approximately 1100-bed acute care tertiary hospital of an Academic Medical Center in Singapore. Adult patients with nasogastric tubes admitted to the general wards were recruited into the study. The colorimeter was attached to the nasogastric tube to detect for the presence of carbon dioxide, suggestive of a tracheobronchial placement. The exact location of the nasogastric tube was subsequently confirmed by a radiographic examination. A total of 192 tests were undertaken. The colorimeter detected carbon dioxide in 29 tested nasogastric tubes, of which radiographic examination confirmed that four tubes were located in the tracheobronchial tract. The colorimeter failed to detect carbon dioxide in one nasogastric tube that was located in the tracheobronchial tract, thus, demonstrating a sensitivity of 0.80 [95% CI (0.376, 0.964)]. The colorimeter detected absence of carbon dioxide in 163 tested nasogastric tubes in which radiographic examination confirmed 160 gastrointestinal and one tracheobronchial placements, demonstrating a specificity of 0.865 [95% CI (0.808, 0.907)]. The colorimeter detected one tracheobronchial nasogastric tube placement that the radiographic examination was misinterpreted. The study found that the use of the colorimeter in the general ward setting was not 100% sensitive or specific in ascertaining the location of a nasogastric tube as previously reported by many studies undertaken in intensive care settings. This is the first study on the use of a colorimeter to confirm the placement of a nasogastric tube in adult patients in the general ward setting. More research on the use of a colorimeter in the general ward setting and its potential use in certain processes for confirming the placement of a nasogastric tube is warranted. Copyright © 2016 Elsevier Ltd. All rights reserved.
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NASA Technical Reports Server (NTRS)
1996-01-01
Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.
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Enthalpy of Vaporization by Gas Chromatography: A Physical Chemistry Experiment
ERIC Educational Resources Information Center
Ellison, Herbert R.
2005-01-01
An experiment is conducted to measure the enthalpy of vaporization of volatile compounds like methylene chloride, carbon tetrachloride, and others by using gas chromatography. This physical property was measured using a very tiny quantity of sample revealing that it is possible to measure the enthalpies of two or more compounds at the same time.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-11
... DEPARTMENT OF COMMERCE International Trade Administration [A-583-008] Circular Welded Carbon Steel... review of the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan.\\1\\ On... review within the original time frame because we require additional time to obtain information from the...
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An experimental study of the composite CNT/copper coating
NASA Astrophysics Data System (ADS)
Panarin, Valentin Ye.; Svavil‧nyi, Nikolai Ye.; Khominich, Anastasiya I.
2018-03-01
This paper presents experimental results on the preparation and investigation of the carbon nanotubes-copper composite material. Carbon nanotubes (CNTs) were synthesized on silicon substrates by the chemical vapor deposition (CVD) method and then filled with copper by evaporation from a melting pot in a vacuum. Copper evenly covered both the surface of the entangled tubes and the free substrate surface between the tubes. To improve the adhesion of tubes and matrix material, a carbon substructure was grown on the surface of tubes by adding working gas plasma to the CNT synthesis area. It is proposed to use a copper coating as a diffusion barrier upon subsequent filling of the reinforcing CNT frame by a carbide-forming materials matrix with predetermined physico-mechanical and tribological properties.
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Thermally Conductive Metal-Tube/Carbon-Composite Joints
NASA Technical Reports Server (NTRS)
Copeland, Robert J.
2004-01-01
An improved method of fabricating joints between metal and carbon-fiber-based composite materials in lightweight radiators and heat sinks has been devised. Carbon-fiber-based composite materials have been used in such heat-transfer devices because they offer a combination of high thermal conductivity and low mass density. Metal tubes are typically used to carry heat-transfer fluids to and from such heat-transfer devices. The present fabrication method helps to ensure that the joints between the metal tubes and the composite-material parts in such heat-transfer devices have both (1) the relatively high thermal conductances needed for efficient transfer of heat and (2) the flexibility needed to accommodate differences among thermal expansions of dissimilar materials in operation over wide temperature ranges. Techniques used previously to join metal tubes with carbon-fiber-based composite parts have included press fitting and bonding with epoxy. Both of these prior techniques have been found to yield joints characterized by relatively high thermal resistances. The present method involves the use of a solder (63 percent Sn, 37 percent Pb) to form a highly thermally conductive joint between a metal tube and a carbon-fiber-based composite structure. Ordinarily, the large differences among the coefficients of thermal expansion of the metal tube, solder, and carbon-fiber-based composite would cause the solder to pull away from the composite upon post-fabrication cooldown from the molten state. In the present method, the structure of the solder is modified (see figure) to enable it to deform readily to accommodate the differential thermal expansion.
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Hierarchically ordered carbon tubes
NASA Astrophysics Data System (ADS)
Pan, Zheng-Wei; Zhu, Hao-Guo; Zhang, Zong-Tao; Im, Hee-Jung; Dai, Sheng; Beach, David B.; Lowndes, Douglas H.
2003-04-01
Micropatterns of hierarchically ordered carbon tubes (i.e., ordered carbon microtubes composed of aligned carbon nanotubes) were grown on a film-like iron/silica substrate consisting of ring-like catalyst patterns. The substrates were prepared by a combined technique, in which the sol-gel method was used to prepare catalyst film and transmission electron microscope grids were used as a shadow mask. In comparison with other techniques that involve sophisticated lithography, this approach represents a simple and low-cost way to the micropatterning of aligned carbon nanotubes.
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Phytoplankton Bloom in North Sea off Scotland
NASA Technical Reports Server (NTRS)
2008-01-01
The northern and western highlands of Scotland were still winter-brown and even dusted with snow in places, but the waters of the North Sea were blooming with phytoplankton on May 8, 2008, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite passed over the region and captured this image. The tiny, plant-like organisms swirled in the waters off the country's east coast, coloring the shallow coastal waters shades of bright blue and green. Phytoplankton are tiny organisms--many are just a single cell--that use chlorophyll and other pigments to capture light for photosynthesis. Because these pigments absorb sunlight, they change the color of the light reflected from the sea surface back to the satellite. Scientists have used observations of 'ocean color' from satellites for more than 20 years to track worldwide patterns in phytoplankton blooms. Phytoplankton are important to the Earth system for a host of reasons, including their status as the base of the ocean food web. In the North Sea, they are the base of the food web that supports Scotland's commercial fisheries, including monkfish and herring. As photosynthesizers, they also play a crucial role in the carbon cycle, removing carbon dioxide from the atmosphere. Some oceanographers are concerned that rising ocean temperatures will slow phytoplankton growth rates, harming marine ecosystems and causing carbon dioxide to accumulate more rapidly in the atmosphere.
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Heat conduction in double-walled carbon nanotubes with intertube additional carbon atoms.
Cui, Liu; Feng, Yanhui; Tan, Peng; Zhang, Xinxin
2015-07-07
Heat conduction of double-walled carbon nanotubes (DWCNTs) with intertube additional carbon atoms was investigated for the first time using a molecular dynamics method. By analyzing the phonon vibrational density of states (VDOS), we revealed that the intertube additional atoms weak the heat conduction along the tube axis. Moreover, the phonon participation ratio (PR) demonstrates that the heat transfer in DWCNTs is dominated by low frequency modes. The added atoms cause the mode weight factor (MWF) of the outer tube to decrease and that of the inner tube to increase, which implies a lower thermal conductivity. The effects of temperature, tube length, and the number and distribution of added atoms were studied. Furthermore, an orthogonal array testing strategy was designed to identify the most important structural factor. It is indicated that the tendencies of thermal conductivity of DWCNTs with added atoms change with temperature and length are similar to bare ones. In addition, thermal conductivity decreases with the increasing number of added atoms, more evidently for atom addition concentrated at some cross-sections rather than uniform addition along the tube length. Simultaneously, the number of added atoms at each cross-section has a considerably more remarkable impact, compared to the tube length and the density of chosen cross-sections to add atoms.
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NASA Astrophysics Data System (ADS)
Karanjule, D. B.; Bhamare, S. S.; Rao, T. H.
2018-04-01
Cold drawing is widely used deformation process for seamless tube manufacturing. Springback is one of the major problem faced in tube drawing. Springback is due to the elastic energy stored in the tubes during forming process. It is found that this springback depends upon Young’s modulus of the material. This paper reports mechanical testing of three grades of steels viz. low carbon steel, medium carbon steel and high carbon steel to measure their Young’s modulus and corresponding springback. The results shows that there is 10-20 % variation in the Young’s modulus and inverse proportion between the springback and Young’s modulus. More the percentage of carbon, more the strength, less the value of Young’s modulus and more will springback. The study further leads to identify optimum die semi angle of 15 degree, land width of 10 mm and drawing speed of 8, 6 and 4 m/min for least springback in all the three grades respectively and die semi angle as a most dominant factor causing springback.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Jing; Chen, Di; Wang, Xuemei
2015-10-12
Ion irradiation effects on thermal property changes are compared between aligned carbon nanotube (A-CNT) films and randomly entangled carbon nanotube (R-CNT) films. After H, C, and Fe ion irradiation, a focusing ion beam with sub-mm diameter is used as a heating source, and an infrared signal is recorded to extract thermal conductivity. Ion irradiation decreases thermal conductivity of A-CNT films, but increases that of R-CNT films. We explain the opposite trends by the fact that neighboring CNT bundles are loosely bonded in A-CNT films, which makes it difficult to create inter-tube linkage/bonding upon ion irradiation. In a comparison, in R-CNTmore » films, which have dense tube networking, carbon displacements are easily trapped between touching tubes and act as inter-tube linkage to promote off-axial phonon transport. The enhancement overcomes the phonon transport loss due to phonon-defect scattering along the axial direction. A model is established to explain the dependence of thermal conductivity changes on ion irradiation parameters including ion species, energies, and current.« less
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Closure device for lead-acid batteries
Ledjeff, Konstantin
1983-01-01
A closure device for lead-acid batteries includes a filter of granulated activated carbon treated to be hydrophobic combined with means for preventing explosion of emitted hydrogen and oxygen gas. The explosion prevention means includes a vertical open-end tube within the closure housing for maintaining a liquid level above side wall openings in an adjacent closed end tube. Gases vent from the battery through a nozzle directed inside the closed end tube against an impingement surface to remove acid droplets. The gases then flow through the side wall openings and the liquid level to quench any possible ignition prior to entering the activated carbon filter. A wick in the activated carbon filter conducts condensed liquid back to the closure housing to replenish the liquid level limited by the open-end tube.
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Blowing Carbon Nanotubes to Carbon Nanobulbs
NASA Astrophysics Data System (ADS)
Su, D. S.; Zhu, Z. P.; Lu, Y.; Schlögl, R.; Weinberg, G.; Liu, Z. Y.
2004-09-01
We report the blowing of multi-walled carbon nanotubes into carbon nanobulbs. This is realized in a unique tube growth environment generated by explosive decomposition of picric acid mixed with nickel formate. The carbon spherical bulbs are characterized by large dimensions (up to 900 nm), thin walls (around 10 nm), and fully hollow cores. The walls are in graphitic structure of sp2 hybridized carbons. Bulb-tube assemblies are found as intermediate derivatives of blowing. A joint action of the filled high-pressure gases and the structural defects in the carbon nanotubes is responsible to the formation of the carbon nanobulbs. Our finding may indicate the possibility to engineer the carbon nanotubes to the designed nanostructures.
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Tansel, Berrin; Surita, Sharon C
2016-06-01
Siloxane levels in biogas can jeopardize the warranties of the engines used at the biogas to energy facilities. The chemical structure of siloxanes consists of silicon and oxygen atoms, alternating in position, with hydrocarbon groups attached to the silicon side chain. Siloxanes can be either in cyclic (D) or linear (L) configuration and referred with a letter corresponding to their structure followed by a number corresponding to the number of silicon atoms present. When siloxanes are burned, the hydrocarbon fraction is lost and silicon is converted to silicates. The purpose of this study was to evaluate the adequacy of activated carbon gas samplers for quantitative analysis of siloxanes in biogas samples. Biogas samples were collected from a landfill and an anaerobic digester using multiple carbon sorbent tubes assembled in series. One set of samples was collected for 30min (sampling 6-L gas), and the second set was collected for 60min (sampling 12-L gas). Carbon particles were thermally desorbed and analyzed by Gas Chromatography Mass Spectrometry (GC/MS). The results showed that biogas sampling using a single tube would not adequately capture octamethyltrisiloxane (L3), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). Even with 4 tubes were used in series, D5 was not captured effectively. The single sorbent tube sampling method was adequate only for capturing trimethylsilanol (TMS) and hexamethyldisiloxane (L2). Affinity of siloxanes for activated carbon decreased with increasing molecular weight. Using multiple carbon sorbent tubes in series can be an appropriate method for developing a standard procedure for determining siloxane levels for low molecular weight siloxanes (up to D3). Appropriate quality assurance and quality control procedures should be developed for adequately quantifying the levels of the higher molecular weight siloxanes in biogas with sorbent tubes. Copyright © 2016 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Sokoloff, J. B.
2018-03-01
Secchi et al. [Nature (London) 537, 210 (2016), 10.1038/nature19315] observed a large enhancement of the permeability and slip length in carbon nanotubes when the tube radius is of the order of 15 nm, but not in boron nitride nanotubes. It will be pointed out that none of the parameters that appear in the usual molecular dynamics treatments of water flow in carbon nanotubes have a length scale comparable to 15 nm, which could account for the observed flow velocity enhancement. It will be demonstrated here, however, that if the friction force between the water and the tube walls in carbon nanotubes is dominated by friction due to electron excitations in the tube walls, the enhanced flow can be accounted for by a reduction in the contribution to the friction due to electron excitations in the wall, resulting from the dependence of the electron energy band gap on the tube radius.
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Planktic foraminifera form their shells by attachment of metastable carbonate particles
NASA Astrophysics Data System (ADS)
Wirth, R.; Jacob, D. E.; Eggins, S.
2016-12-01
Planktic foraminifera shells contribute up to half the inorganic carbon exported from the surface ocean to the seafloor. Their tiny calcium carbonate shells are preserved in sediments as calcite, and provide our most valuable geochemical archive of changes surface ocean conditions and climate spanning the last 100 million years. Here we show the shells of living planktic foraminifers Orbulina universa and Neogloboquadrina dutertrei consist of nano-particulate vaterite and amorphous calcium carbonate. This indicates formation via a non-classical crystallization pathway involving metastable carbonate intermediate phases before transforming to calcite, and requires a new perspective on how geochemical proxies are incorporated into planktic foraminifer shells. Our findings indicate planktic foraminifer shells could be far more susceptible to dissolution and ocean acidification than previously thought, and account for unexpected shell dissolution above the calcite saturation horizon in the ocean, which is a major uncertainty in modelling oceanic carbon fluxes.
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Process for producing an activated carbon adsorbent with integral heat transfer apparatus
NASA Technical Reports Server (NTRS)
Jones, Jack A. (Inventor); Yavrouian, Andre H. (Inventor)
1996-01-01
A process for producing an integral adsorbent-heat exchanger apparatus useful in ammonia refrigerant heat pump systems. In one embodiment, the process wets an activated carbon particles-solvent mixture with a binder-solvent mixture, presses the binder wetted activated carbon mixture on a metal tube surface and thereafter pyrolyzes the mixture to form a bonded activated carbon matrix adjoined to the tube surface. The integral apparatus can be easily and inexpensively produced by the process in large quantities.
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Translocation of single-stranded DNA through single-walled carbon nanotubes.
Liu, Haitao; He, Jin; Tang, Jinyao; Liu, Hao; Pang, Pei; Cao, Di; Krstic, Predrag; Joseph, Sony; Lindsay, Stuart; Nuckolls, Colin
2010-01-01
We report the fabrication of devices in which one single-walled carbon nanotube spans a barrier between two fluid reservoirs, enabling direct electrical measurement of ion transport through the tube. A fraction of the tubes pass anomalously high ionic currents. Electrophoretic transport of small single-stranded DNA oligomers through these tubes is marked by large transient increases in ion current and was confirmed by polymerase chain reaction analysis. Each current pulse contains about 10(7) charges, an enormous amplification of the translocated charge. Carbon nanotubes simplify the construction of nanopores, permit new types of electrical measurements, and may open avenues for control of DNA translocation.
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Carbon Tube Electrodes for Electrocardiography-Gated Cardiac Multimodality Imaging in Mice
Choquet, Philippe; Goetz, Christian; Aubertin, Gaelle; Hubele, Fabrice; Sannié, Sébastien; Constantinesco, André
2011-01-01
This report describes a simple design of noninvasive carbon tube electrodes that facilitates electrocardiography (ECG) in mice during cardiac multimodality preclinical imaging. Both forepaws and the left hindpaw, covered by conductive gel, of mice were placed into the openings of small carbon tubes. Cardiac ECG-gated single-photon emission CT, X-ray CT, and MRI were tested (n = 60) in 20 mice. For all applications, electrodes were used in a warmed multimodality imaging cell. A heart rate of 563 ± 48 bpm was recorded from anesthetized mice regardless of the imaging technique used, with acquisition times ranging from 1 to 2 h. PMID:21333165
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Characterization of Thin Walled Mo Tubing produced by FBCVD
DOE Office of Scientific and Technical Information (OSTI.GOV)
Beaux, Miles Frank; Usov, Igor Olegovich
2016-01-21
The goal of this report is to delineate the results of material characterization performed on Mo tubing produced via the fluidized bed chemical vapor deposition (FBCVD) method. Scanning electron microscopy (SEM) imaging reveals that small randomly oriented grains are achieved in the Mo deposition, but do not persist throughout the entire thickness of the material. Energy dispersive spectroscopy (EDS) reveals the Mo tubes contain residual chlorine and oxygen. EDS measurements on the tube surfaces separated from glass and quartz substrates reveal substrate material adhered to this surface. X-ray diffraction (XRD) revealed the presence of carbon contaminant in the form ofmore » Mo 2C and oxygen in the form of MoO 2. Combustion infrared detection (CID) and inert gas fusion (IGF) performed at Luvak Inc. was used to quantify weight percentages of oxygen and carbon in the tubes produced. Hardness value of the FBCVD Mo was found to be comparable to low carbon arc cast molybdenum.« less
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-29
... and its individual members, Allied Tube & Conduit, IPSCO Tubulars, Inc., Sharon Tube Company, Western Tube & Conduit Corporation, and Wheatland Tube Company (collectively, ``Petitioner''), that the... pipes and tubes, of circular cross-section, and with an outside diameter of 0.372 inches (9.45 mm) or...
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Carbon coated anatase TiO2 mesocrystals enabling ultrastable and robust sodium storage
NASA Astrophysics Data System (ADS)
Zhang, Weifeng; Lan, Tongbin; Ding, Tianli; Wu, Nae-Lih; Wei, Mingdeng
2017-08-01
Nanoporous anatase TiO2 mesocrystals with tunable architectures and crystalline phases were successfully fabricated in the presence of the butyl oleate and oleylamine. Especially, the introduced surfactants served as a carbon source, bring a uniform carbon layer (about 2-8 nm) for heightening the electronic conductivity. The carbon coated TiO2 mesocrystals assembled from crystalline tiny subunits have more space sites for sodium-ion storage. When the material was applied as an electrode material in rechargeable sodium-ion batteries, it exhibited a superior capacity of about 90 mA h g-1 at 20 C (1 C = 168 mA g-1) and a highly reversible capacity for 5000 cycles, which is the longest cycle life reported for sodium storage in TiO2 electrodes.
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Fabrication of stainless steel clad tubing. [gas pressure bonding
NASA Technical Reports Server (NTRS)
Kovach, C. W.
1978-01-01
The feasibility of producing stainless steel clad carbon steel tubing by a gas pressure bonding process was evaluated. Such a tube product could provide substantial chromium savings over monolithic stainless tubing in the event of a serious chromium shortage. The process consists of the initial assembly of three component tubesets from conventionally produced tubing, the formation of a strong metallurgical bond between the three components by gas pressure bonding, and conventional cold draw and anneal processing to final size. The quality of the tubes produced was excellent from the standpoint of bond strength, mechanical, and forming properties. The only significant quality problem encountered was carburization of the stainless clad by the carbon steel core which can be overcome by further refinement through at least three different approaches. The estimated cost of clad tubing produced by this process is greater than that for monolithic stainless tubing, but not so high as to make the process impractical as a chromium conservation method.
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Wang, Meimei; Xia, Yonggao; Wang, Xiaoyan; Xiao, Ying; Liu, Rui; Wu, Qiang; Qiu, Bao; Metwalli, Ezzeldin; Xia, Senlin; Yao, Yuan; Chen, Guoxin; Liu, Yan; Liu, Zhaoping; Meng, Jian-Qiang; Yang, Zhaohui; Sun, Ling-Dong; Yan, Chun-Hua; Müller-Buschbaum, Peter; Pan, Jing; Cheng, Ya-Jun
2016-06-08
A new facile scalable method has been developed to synthesize silicon oxycarbide (SiOC)/carbon nanohybrids using difunctional dental methacrylate monomers as solvent and carbon source and the silane coupling agent as the precursor for SiOC. The content (from 100% to 40% by mass) and structure (ratio of disordered carbon over ordered carbon) of the free carbon matrix have been systematically tuned by varying the mass ratio of methacryloxypropyltrimethoxysilane (MPTMS) over the total mass of the resin monomers from 0.0 to 6.0. Compared to the bare carbon anode, the introduction of MPTMS significantly improves the electrochemical performance as a lithium-ion battery anode. The initial and cycled discharge/charge capacities of the SiOC/C nanohybrid anodes reach maximum with the MPTMS ratio of 0.50, which displays very good rate performance as well. Detailed structures and electrochemical performance as lithium-ion battery anodes have been systematically investigated. The structure-property correlation and corresponding mechanism have been discussed.
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Chandler, David L
2015-01-01
The smooth, powerful muscles of a newborn baby?s heart are pulsing normally, squeezing in and letting go rhythmically as a 3-mm-wide catheter-like tube snakes its way through, entering via an artery and being guided slowly by a surgeon. When it reaches its target?a protruding knot of malformed muscle tissue within a ventricle that has been partly blocking the valve?the tip of the precisely controlled tube whirs into action, with tiny scissor-like rotating blades gently grinding up the excess tissue as those pieces are sucked back into the device, leaving no floating particles that could lead to a blockage elsewhere. The defect is fully removed, and the heart?s function is restored to normal, leaving the child with the prospect of a normal life. The whole minimally invasive process takes place inside a beating heart and would otherwise have required open-heart surgery, with the heart stopped for a cardiopulmonary bypass.
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Wavy carbon: A new series of carbon structures explored by quantum chemical calculations
NASA Astrophysics Data System (ADS)
Ohno, Koichi; Satoh, Hiroko; Iwamoto, Takeaki; Tokoyama, Hiroaki; Yamakado, Hideo
2015-10-01
A new carbon family adopting wavy structures has been found by quantum chemical calculations. The key motif of this family is a condensed four-membered ring. Periodically wavy-carbon sheets (wavy-Cn sheets, n = 2, 6, and 8) as well as wavy-C36 tube were found to be very similar to the previously reported prism-Cn carbon tubes (n = 5, 6, and 8) in several respects, including the relative energies per one carbon atom with respect to graphene, CC bond lengths, and CCC bond angles. Because of very high relative energies with respect to graphene (206-253 kJ mol-1), the wavy-carbons may behave as energy reserving materials.
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NASA Astrophysics Data System (ADS)
Tripathy, Srijeet; Bhattacharyya, Tarun Kanti
2016-09-01
Due to excellent transport properties, Carbon nanotubes (CNTs) show a lot of promise in sensor and interconnect technology. However, recent studies indicate that the conductance in CNT/CNT junctions are strongly affected by the morphology and orientation between the tubes. For proper utilization of such junctions in the development of CNT based technology, it is essential to study the electronic properties of such junctions. This work presents a theoretical study of the electrical transport properties of metallic Carbon nanotube homo-junctions. The study focuses on discerning the role of inter-tube interactions, quantum interference and scattering on the transport properties on junctions between identical tubes. The electronic structure and transport calculations are conducted with an Extended Hückel Theory-Non Equilibrium Green's Function based model. The calculations indicate conductance to be varying with a changing crossing angle, with maximum conductance corresponding to lattice registry, i.e. parallel configuration between the two tubes. Further calculations for such parallel configurations indicate onset of short and long range oscillations in conductance with respect to changing overlap length. These oscillations are attributed to inter-tube coupling effects owing to changing π orbital overlap, carrier scattering and quantum interference of the incident, transmitted and reflected waves at the inter-tube junction.
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NASA Astrophysics Data System (ADS)
Kuwahara, Ken; Higashiiu, Shinya; Ito, Daisuke; Koyama, Shigeru
This paper deals with the experimental study on cooling heat transfer of supercritical carbon dioxide inside micro-fin tubes. The geometrical parameters in micro-fin tubes used in the present study are 6.02 mm in outer diameter, 4.76 mm to 5.11 mm in average inner diameter, 0.15 mm to 0.24 mm in fin height, 5 to 25 in helix angle, 46 to 52 in number of fins and 1.4 to 2.3 in area expansion ratio. Heat transfer coefficients were measured at 8-10 MPa in pressure, 360-690 kg/(m2•s) in mass velocity and 20-75 °C in CO2 temperature. The measured heat transfer coefficients of micro-fin tubes were 1.4 to 2 times higher than those of the smooth tube having 4.42 in inner diameter. The predicted heat transfer coefficients using the correlation equation, which was developed for single-phase turbulent fluid flow inside micro-fin-tubes, showed large deviations to the measured values. The new correlation to predict cooling heat transfer coefficient of supercritical carbon dioxide inside micro-fin tubes was developed taking into account the shape of fins based on experimental data empirically. This correlation equation agreed within ±20% of almost all of the experimental data.
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1/f noise in metallic and semiconducting carbon nanotubes
NASA Astrophysics Data System (ADS)
Reza, Shahed; Huynh, Quyen T.; Bosman, Gijs; Sippel-Oakley, Jennifer; Rinzler, Andrew G.
2006-11-01
The charge transport and noise properties of three terminal, gated devices containing multiple single-wall metallic and semiconducting carbon nanotubes were measured at room temperature. Applying a high voltage pulsed bias at the drain terminal the metallic tubes were ablated sequentially, enabling the separation of measured conductance and 1/f noise into metallic and semiconducting nanotube contributions. The relative low frequency excess noise of the metallic tubes was observed to be two orders of magnitude lower than that of the semiconductor tubes.
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Remotely Triggered Cisplatin Release from Carbon Nanocapsules by Radiofrequency Fields
Raoof, Mustafa; Cisneros, Brandon T.; Guven, Adem; Corr, Stuart J.; Wilson, Lon J.; Curley, Steven A.
2013-01-01
The efficacy of nanoparticle-mediated drug delivery is limited by its peri-vascular sequestration, thus necessitating a strategy to trigger drug release from such intra-tumoral nanocarrier-drug depots. In our efforts to explore remotely-activated nanocarriers, we have developed carbon nanocapsules comprised of an ultrashort carbon nanotube shell (US-tubes) loaded with cisplatin (CDDP@US-tubes) and covered with a Pluronic surfactant wrapping to minimize passive release. We demonstrate here that non-invasive radiofrequency (RF) field activation of the CDDP@US-tubes produces heat that causes Pluronic disruption which triggers cisplatin release in an RF-dependent manner. Furthermore, release-dependent cytotoxicity is demonstrated in human hepatocellular carcinoma cell lines. PMID:23228421
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Investigation of the Radial Compression of Carbon Nanotubes with a Scanning Probe Microscope
NASA Astrophysics Data System (ADS)
Shen, Weidian; Jiang, Bin; Han, Bao Shan; Xie, Si-Shen
2001-03-01
Carbon nanotubes have attracted great interest since they were first synthesized. The tubes have substantial promise in a variety of applications due to their unique properties. Efforts have been made to characterize the mechanical properties of the tubes. However, previous work has concentrated on the tubes’ longitudinal properties, and studies of their radial properties lag behind. We have operated a scanning probe microscope, NanoScopeTM IIIa, in the indentation/scratching mode to carry out a nanoindentation test on the top of multiwalled carbon nanotubes. We measured the correlation between the radial stress and the tube compression, and thereby determined the radial compressive elastic modulus at different compressive forces. The measurements also allowed us to estimate the radial compressive strength of the tubes. Support of this work by an Eastern Michigan University Faculty Research Fellowship and by the K. C. Wong Education Foundation, Hong Kong is gratefully acknowledged.
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NASA Astrophysics Data System (ADS)
Santos, Hernán; Latgé, A.; Alvarellos, J. E.; Chico, Leonor
2016-04-01
We study the effect of the Rashba spin-orbit interaction in the quantum transport of carbon nanotubes with arbitrary chiralities. For certain spin directions, we find a strong spin-polarized electrical current that depends on the diameter of the tube, the length of the Rashba region, and on the tube chirality. Predictions for the spin-dependent conductances are presented for different families of achiral and chiral tubes. We have found that different symmetries acting on spatial and spin variables have to be considered in order to explain the relations between spin-resolved conductances in carbon nanotubes. These symmetries are more general than those employed in planar graphene systems. Our results indicate the possibility of having stable spin-polarized electrical currents in absence of external magnetic fields or magnetic impurities in carbon nanotubes.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-02-02
... DEPARTMENT OF COMMERCE International Trade Administration [A-583-803] Light-Walled Welded... revocation of the antidumping duty order on light-walled welded rectangular carbon steel tubing from Taiwan..., and the ITC instituted, the sunset review of the antidumping duty order \\1\\ on light-walled welded...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-02-11
... Tube Manufacturing Co., Ltd.; Huludao City Steel Pipe Industrial; Jiangsu Changbao Steel Tube Co., Ltd... Quality Steel Pipe From the People's Republic of China: Rescission of Countervailing Duty Administrative... countervailing duty order on circular welded carbon quality steel pipe from the People's Republic of China (``PRC...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-01-24
... Steel Tube Manufacturing Co., Ltd., Huludao City Steel Pipe Industrial, Jiangsu Changbao Steel Tube Co... Quality Steel Pipe From the People's Republic of China: Rescission of Antidumping Duty Administrative... of the antidumping duty order on circular welded carbon quality steel pipe from the People's Republic...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-01-20
... DEPARTMENT OF COMMERCE International Trade Administration [A-583-008] Circular Welded Carbon Steel... Steel Pipes and Tubes From Taiwan: Notice of Partial Rescission of Antidumping Duty Administrative... complete the preliminary results of this review within the original time frame because we require...
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-08-13
... Co., Ltd., Tension Steel Industries Co., Ltd., and Yieh Phui Enterprise Co., Ltd. Petitioner... Steel Industries Co., Ltd.; and (5) Yieh Phui Enterprise Co., Ltd. This review will continue with... Carbon Steel Pipes and Tubes From Taiwan: Partial Rescission of Antidumping Duty Administrative Review...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-13
... Kao Hsiung Chang Iron & Steel Corp.); and (6) Tension Steel Industries Co. Ltd. The Department... Carbon Steel Pipes and Tubes From Taiwan: Notice of Rescission of Antidumping Duty Administrative Review... response to a request from United States Steel Corporation, an interested party, the Department of Commerce...
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Chirality correlation in double-wall carbon nanotubes as studied by electron diffraction
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hirahara, Kaori; Bandow, Shunji; Kociak, Mathieu
2006-05-15
Structural correlation between two adjacent graphitic layers in double-wall carbon nanotubes (DWNTs) was systematically examined by using electron diffraction. Chiral angles and tube diameters were carefully measured, and the chiral indices of individual DWNTs were accurately determined. As a result, it was found that the interlayer distances of DWNTs were widely distributed in the range between 0.34 and 0.38 nm. Chiralities of the inner and outer tubes tended to be distributed at higher chiral angles, approaching 30 deg., for the tubes with diameter D<{approx}3 nm. On the other hand, for the tubes with D>{approx}3 nm, the chiral angles were widelymore » distributed, covering the chiral map entirely. Therefore, we consider that tubes with small diameters have a tendency to form armchair type. Correlation of chiralities between the inner and outer tubes was found to be random.« less
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Modelling the side impact of carbon fibre tubes
NASA Astrophysics Data System (ADS)
Sudharsan, Ms R.; Rolfe, B. F., Dr; Hodgson, P. D., Prof
2010-06-01
Metallic tubes have been extensively studied for their crashworthiness as they closely resemble automotive crash rails. Recently, the demand to improve fuel economy and reduce vehicle emissions has led automobile manufacturers to explore the crash properties of light weight materials such as fibre reinforced polymer composites, metallic foams and sandwich structures in order to use them as crash barriers. This paper discusses the response of carbon fibre reinforced polymer (CFRP) tubes and their failure mechanisms during side impact. The energy absorption of CFRP tubes is compared to similar Aluminium tubes. The response of the CFRP tubes during impact was modelled using Abaqus finite element software with a composite fabric material model. The material inputs were given based on standard tension and compression test results and the in-plane damage was defined based on cyclic shear tests. The failure modes and energy absorption observed during the tests were well represented by the finite element model.
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Predicting the mechanical behaviour of Kevlar/epoxy and carbon/epoxy filament-wound tubes
NASA Astrophysics Data System (ADS)
Cazeneuve, C.; Joguet, P.; Maile, J. C.; Oytana, C.
1992-11-01
The axial, hoop and shear moduli and failure conditions of carbon/epoxy and Kevlar/epoxy filament-wound tubes have been determined through respective applications of internal pressure, tension and torsion. The introduction in the laminated plate theory of a gradual reduction in individual moduli makes it possible to overcome the limitations of the theory and enables accurate predictions to be made of the linear and non-linear stress/strain curves of 90 deg +/- 0/90 deg tubes. The existence of a dominant layer in the failure of the multilayered tubes has been shown experimentally. When associated with a failure criterion applied to the dominant layer, the new model permits the prediction of tube failure. Agreement between calculated and experimental data is better than 5 percent.
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Note: Development of target changeable palm-top pyroelectric x-ray tube
DOE Office of Scientific and Technical Information (OSTI.GOV)
Imashuku, Susumu; Kawai, Jun
2012-01-15
A target changeable palm-top size x-ray tube was realized using pyroelectric crystal and detachable vacuum flanges. The target metals can be exchanged easily by attaching them on the brass stage with carbon tape. When silver and titanium palates (area: 10 mm{sup 2}) were used as targets, silver L{alpha} and titanium K lines were clearly observed by bombarding electrons on the targets for 90 s. The intensities were the same or higher than those of previously reported pyroelectric x-ray tubes. Chromium, iron, nickel, copper, and zinc K lines in the x-ray tube (stainless steel and brass) disappeared by replacing the brassmore » stage and the stainless steel vacuum flange with a carbon stage and a glass tube, respectively.« less
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Impact damage resistance of carbon/epoxy composite tubes for the DC-XA liquid hydrogen feedline
NASA Technical Reports Server (NTRS)
Nettles, A. T.
1995-01-01
Low-velocity impacts were inflicted upon two elbow sections of carbon/epoxy feedline that are to be a part of the Delta Clipper-XA flight vehicle. A soap-based liquid leak detector solution was used to inspect the impact sites for leaks of pressurized gas that was pumped into the tube. Visual surface damage was noted and recorded for each impact site. After impact testing of each of the two sections of tubes was completed, the damage zones were disected from the tube and cross sectioned through the impact site. These specimens were polished after potting them in epoxy and were examined for microcracking using a fluorescent dye penetrant technique. The results showed that nonvisible damage could cause microcracking, thereby resulting in leaks through the tube wall.
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Saline soaked pledgets prevent carbon dioxide laser-induced endotracheal tube cuff ignition.
Sosis, M B
1995-08-01
To determine whether saline soaked pledgets would protect the cuffs of polyvinylchloride (PVC) endotracheal tubes from carbon dioxide (CO2) laser-induced combustion. 12 PVC endotracheal tubes were studied. The cuffed end of each was placed in a graduated cylinder and flushed with 5 L/min of oxygen for 5 minutes. The endotracheal tube's cuff was then inflated with air and the system pressure set to 20 cm H2O. Research laboratory of a university hospital. Six of the endotracheal tube cuffs were protected with 1 inch by 3 inch saline soaked pledgets and six were left unprotected. A CO2 laser set to 40 watts was then fired at the cuffs. All six unprotected cuffs were ignited in less than 1 second. No significant combustion occurred at the six pledget protected endotracheal tube cuffs after 1 minute of laser fire. Under the conditions of this experiment, saline soaked pledgets protected PVC endotracheal tube cuffs from the CO2 laser.
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Cold cathode vacuum discharge tube
Boettcher, Gordon E.
1998-01-01
A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.
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Carbon nanoelectronics: unzipping tubes into graphene ribbons.
Santos, H; Chico, L; Brey, L
2009-08-21
We report on the transport properties of novel carbon nanostructures made of partially unzipped carbon nanotubes, which can be regarded as a seamless junction of a tube and a nanoribbon. We find that graphene nanoribbons act at certain energy ranges as perfect valley filters for carbon nanotubes, with the maximum possible conductance. Our results show that a partially unzipped carbon nanotube is a magnetoresistive device, with a very large value of magnetoresistance. We explore the properties of several structures combining nanotubes and graphene nanoribbons, demonstrating that they behave as optimal contacts for each other, and opening a new route for the design of mixed graphene-nanotube devices.
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Optical properties of carbon nanotubes
NASA Astrophysics Data System (ADS)
Chen, Gugang
This thesis addresses the optical properties of novel carbon filamentary nanomaterials: single-walled carbon nanotubes (SWNTs), double-walled carbon nanotubes (DWNTs), and SWNTs with interior C60 molecules ("peapods"). Optical reflectance spectra of bundled SWNTs are discussed in terms of their electronic energy band structure. An Effective Medium Model for a composite material was found to provide a reasonable description of the spectra. Furthermore, we have learned from optical absorption studies of DWNTs and C60-peapods that the host tube and the encapsulant interact weakly; small shifts in interband absorption structure were observed. Resonant Raman scattering studies on SWNTs synthesized via the HiPCO process show that the "zone-folding" approximation for phonons and electrons works reasonably well, even for small diameter (d < 1 nm) tubes. The energy of optical transitions between van Hove singularities in the electronic density of states computed from the "zone-folding" model (with gamma0 = 2.9 eV) agree well with the resonant conditions for Raman scattering. Small diameter tubes were found to exhibit additional sharp Raman bands in the frequency range 500-1200 cm-1 with an, as yet, undetermined origin. The Raman spectrum of a DWNT was found to be well described by a superposition of the Raman spectra expected for inner and outer tubes, i.e., no charge transfer occurs and the weak van der Waals (vdW) interaction between tubes does not have significant impact on the phonons. A ˜7 cm-1 downshift of the small diameter, inner-tube tangential mode frequency was observed, however, but attributed to a tube wall curvature effect, rather than the vdW interaction. Finally, we studied the chemical doping of DWNTs, where the dopant (Br anions) is chemically bound to the outside of the outer tube. The doped DWNT system is a model for a cylindrical molecular capacitor. We found experimentally that 90% of the positive charge resides on the outer tube, so that most of electric field on the inner tube is screened, i.e., we have observed a molecular Faraday cage effect. A self-consistent theoretical model in the tight-binding approximation with a classical electrostatic energy term is in good agreement with our experimental results.
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NASA Astrophysics Data System (ADS)
Huang, Ying; Zhao, Yunong; Wang, Yang; Guo, Xiaohui; Zhang, Yangyang; Liu, Ping; Liu, Caixia; Zhang, Yugang
2018-03-01
Strain sensors used as flexible and wearable electronic devices have improved prospects in the fields of artificial skin, robotics, human-machine interfaces, and healthcare. This work introduces a highly stretchable fiber-based strain sensor with a laminated structure made up of a graphene nanoplatelet layer and a carbon black/single-walled carbon nanotube synergetic conductive network layer. An ultrathin, flexible, and elastic two-layer polyurethane (PU) yarn substrate was successively deposited by a novel chemical bonding-based layered dip-coating process. These strain sensors demonstrated high stretchability (˜350%), little hysteresis, and long-term durability (over 2400 cycles) due to the favorable tensile properties of the PU substrate. The linearity of the strain sensor could reach an adjusted R-squared of 0.990 at 100% strain, which is better than most of the recently reported strain sensors. Meanwhile, the strain sensor exhibited good sensibility, rapid response, and a lower detection limit. The lower detection limit benefited from the hydrogen bond-assisted laminated structure and continuous conductive path. Finally, a series of experiments were carried out based on the special features of the PU strain sensor to show its capacity of detecting and monitoring tiny human motions.
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46 CFR 56.01-2 - Incorporation by reference.
Code of Federal Regulations, 2012 CFR
2012-10-01
... Steel Pipe for High-Temperature Service (“ASTM A 106”), 56.60-1; (5) ASTM A 126-95, Standard... (1996), Standard Specification for Seamless Carbon Steel Boiler Tubes for High-Pressure Service (“ASTM A...-Resistance-Welded Carbon Steel Boiler and Superheater Tubes for High-Pressure Service (“ASTM A 226”), 56.60-1...
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Continuous approximation for interaction energy of adamantane encapsulated inside carbon nanotubes
NASA Astrophysics Data System (ADS)
Baowan, Duangkamon; Hill, James M.; Bacsa, Wolfgang
2018-02-01
The interaction energy for two adjacent adamantane molecules and that of adamantane molecules encapsulated inside carbon nanotubes are investigated considering only dipole-dipole induced interaction. The Lennard-Jones potential and the continuous approximation are utilised to derive analytical expressions for these interaction energies. The equilibrium distance 3.281 Å between two adamantane molecules is determined. The smallest carbon nanotube radius b0 that can encapsulate the adamantane molecule and the radius of the tube bmax that gives the maximum suction energy, linearly depend on the adamantane radius, are calculated. For larger diameter tubes, the off axis position has been calculated, and equilibrium distance between molecule and tube wall is found to be close to the interlayer spacing in graphene.
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Effects of Structural Deformation and Tube Chirality on Electronic Conductance of Carbon Nanotubes
NASA Technical Reports Server (NTRS)
Svizhenko, Alexei; Maiti, Amitesh; Anantram, M. P.; Biegel, Bryan A. (Technical Monitor)
2002-01-01
A combination of large scale classical force-field (UFF), density functional theory (DFT), and tight-binding Green's function transport calculations is used to study the electronic properties of carbon nanotubes under the twist, bending, and atomic force microscope (AFM)-tip deformation. We found that in agreement with experiment a significant change in electronic conductance can be induced by AFM-tip deformation of metallic zigzag tubes and by twist deformation of armchair tubes. The effect is explained in terms of bandstructure change under deformation.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Whidden, K.J.; Bottjer, D.J.
Silicification in carbonates, particularly silicified trace fossils, has received relatively little previous study. Chert comprises a significant percentage of the upper Fossil Mountain Member of the Kaibab Formation, a Permian epicontinental limestone. Distribution and origin of this chert were studied from outcrops in southwestern Utah. The origin of much of this chert is believed to be as silicified Thalassinoides burrows. Field evidence for trace fossil silicification includes (1) silicified cylindrical tubes with Y-shaped branching patterns as well as hollow tubes, and (2) polygonal box-work patterns of tubes. In addition, brachiopods, bryozoans, and abundant specimens of the sponge Actinocelia maendrina Finksmore » are also silicified. Recognition of silicified trace fossils in carbonates provides a different approach to the study of early diagenetic silica precipitation. These silicified trace fossils also represent new information on bioturbation in ancient carbonates, a subject that has, until recently, been relatively unstudied.« less
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NASA Astrophysics Data System (ADS)
Fata, A.; Eftekhari, M.; Faraji, G.; Mosavi Mashhadi, M.
2018-04-01
In the current study, combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE), as a recently developed severe plastic deformation (SPD) method, were applied at 300 °C on a commercial Mg-3Al-1Zn alloy tubes to achieve an ultrafine grained structure. Then, the microstructure, hardness, tensile properties, and fractography evaluations were done at room temperature on the SPD-processed samples. Also, to study the hot tensile ductility of the SPD-processed samples, tensile testing was performed at an elevated temperature of 400 °C, and then, the fractured surface of the tensile samples was studied. It was observed that a bimodal microstructure, with large gains surrounded by many tiny ones, was created in the sample processed by PTCAP followed by TBE. This microstructure led to reach higher hardness and higher strength at room temperature and also led to reach very high elongation to failure ( 181%) at 400 °C. Also, the value of elongation to failure for this sample was 14.1% at room temperature. The fractographic SEM images showed the occurrence of predominately ductile fracture in the samples pulled at 400 °C. This was mostly due to the nucleation of microvoids and their subsequent growth and coalescence with each other.
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NASA Astrophysics Data System (ADS)
Fata, A.; Eftekhari, M.; Faraji, G.; Mosavi Mashhadi, M.
2018-05-01
In the current study, combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE), as a recently developed severe plastic deformation (SPD) method, were applied at 300 °C on a commercial Mg-3Al-1Zn alloy tubes to achieve an ultrafine grained structure. Then, the microstructure, hardness, tensile properties, and fractography evaluations were done at room temperature on the SPD-processed samples. Also, to study the hot tensile ductility of the SPD-processed samples, tensile testing was performed at an elevated temperature of 400 °C, and then, the fractured surface of the tensile samples was studied. It was observed that a bimodal microstructure, with large gains surrounded by many tiny ones, was created in the sample processed by PTCAP followed by TBE. This microstructure led to reach higher hardness and higher strength at room temperature and also led to reach very high elongation to failure ( 181%) at 400 °C. Also, the value of elongation to failure for this sample was 14.1% at room temperature. The fractographic SEM images showed the occurrence of predominately ductile fracture in the samples pulled at 400 °C. This was mostly due to the nucleation of microvoids and their subsequent growth and coalescence with each other.
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Park, Sin Young; Cheong, Won Jo
2016-05-01
Tiny polyether ether ketone encased monolith frits have been prepared by modified catalytic sulfonation of the inner surface of polyether ether tubing (1.6 mm od, 0.25 mm id) followed by modified formation of organic monolith and cutting of the tubing into slices. The frit was placed below the central hole of the column outlet union and supported by a combination of a silica capillary (0.365 mm od, 0.05 mm id) and a polyether ether ketone sleeve (1.6 mm od, 0.38 mm id) tightened with a nut and a ferrule when the column was packed to prevent sinking of the frit element into the union hole (0.25 mm opening) otherwise. The column packed this way with the frits investigated in this study has shown better separation performance owing to the reduced frit volume in comparison to the column packed with a commercial stainless-steel screen frit. This study establishes the strategy of disposable microcolumns in which cheap disposable frits are used whenever the column is re-packed to yield columns of even better chromatographic performance than the columns with commercial frits. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-02-08
... the specific chemistry of the steel (i.e., carbon, stainless steel, or other alloy steel), and without... collar green tubes) and unfinished drill pipe (including drill pipe green tubes, which are tubes meeting...
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Microphone Detects Boiler-Tube Leaks
NASA Technical Reports Server (NTRS)
Parthasarathy, S. P.
1985-01-01
Unit simple, sensitive, rugged, and reliable. Diaphragmless microphone detects leaks from small boiler tubes. Porous plug retains carbon granules in tube while allowing pressure changes to penetrate to granules. Has greater life expectancy than previous controllers and used in variety of hot corrosive atmospheres.
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Electrochemical Characterization of Carbon Nanotubes for Fuel Cell MEA's
NASA Technical Reports Server (NTRS)
Panagaris, Jael; Loyselle, Patricia
2004-01-01
Single-walled and multi-walled carbon nanotubes from different sources have been evaluated before and after sonication to identify structural differences and evaluate electrochemical performance. Raman spectral analysis and cyclic voltammetry in situ with QCM were the principle means of evaluating the tubes. The raman data indicates that sonication in toluene modifies the structural properties of the nanotubes. Sonication also affects the electrochemical performance of single-walled nanotubes and the multi-walled tubes differently. The characterization of different types of carbon nanotubes leads up to identifying a potential candidate for incorporating carbon nanotubes for fuel cell MEA structures.
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Cold cathode vacuum discharge tube
Boettcher, G.E.
1998-03-10
A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.
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Shabalovskaya, S A; Anderegg, J; Laab, F; Thiel, P A; Rondelli, G
2003-04-15
The surface conditions of Nitinol wires and tubing were evaluated with the use of X-ray photoelectron spectroscopy, high-resolution Auger spectroscopy, electron backscattering, and scanning-electron microscopy. Samples were studied in the as-received state as well as after chemical etching, aging in boiling water, and heat treatment, and compared to a mechanically polished 600-grit-finish Nitinol surface treated similarly. General regularities in surface behavior induced by the examined surface treatments are similar for wires, tubing, and studied as-cast alloy, though certain differences in surface Ni concentration were observed. Nitinol wires and tubing from various suppliers demonstrated great variability in Ni surface concentration (0.5-15 at.%) and Ti/Ni ratio (0.4-35). The wires in the as-received state, with the exception of those with a black oxide originating in the processing procedure, revealed nickel and titanium on the surface in both elemental and oxidized states, indicating a nonpassive surface. Shape-setting heat treatment at 500 degrees C for 15 min resulted in tremendous increase in the surface Ni concentration and complete Ni oxidation. Preliminary chemical etching and boiling in water successfully prevented surface enrichment in Ni, initially resulting from heat treatment. A stoichiometric uniformly amorphous TiO(2) oxide generated during chemical etching and aging in boiling water was reconstructed at 700 degrees C, revealing rutile structure. Copyright 2003 Wiley Periodicals, Inc.
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The Streaming Potential Generated by Flow of Wet Steam in Capillary Tubes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Marsden, S.S. Jr.; Tyran, Craig K.
1986-01-21
For a constant pressure differential, the flow of wet steam generated electric potentials which increased with time and did not reach equilibrium values. These potentials were found to increase to values greater than 100 volts. The reason for this kind of potential build-up behavior was the presence of tiny flowing water slugs which were interspersed with electrically nonconductive steam vapor slugs. The measured electric potential for wet steam increased with pressure differential, but the relationship was not linear. The increase in potential with pressure drop was attributed both to an increase in fluid flow rate and changes in the wetmore » steam quality.« less
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NASA Technical Reports Server (NTRS)
1994-01-01
In laparoscopic surgery, tiny incisions are made in the patient's body and a laparoscope (an optical tube with a camera at the end) is inserted. The camera's image is projected onto two video screens, whose views guide the surgeon through the procedure. AESOP, a medical robot developed by Computer Motion, Inc. with NASA assistance, eliminates the need for a human assistant to operate the camera. The surgeon uses a foot pedal control to move the device, allowing him to use both hands during the surgery. Miscommunication is avoided; AESOP's movement is smooth and steady, and the memory vision is invaluable. Operations can be completed more quickly, and the patient spends less time under anesthesia. AESOP has been approved by the FDA.
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RP-1 Thermal Stability and Copper Based Materials Compatibility Study
NASA Technical Reports Server (NTRS)
Stiegemeier, B. R.; Meyer, M. L.; Driscoll, E.
2005-01-01
A series of electrically heated tube tests was performed at the NASA Glenn Research Center s Heated Tube Facility to investigate the effect that sulfur content, test duration, and tube material play in the overall thermal stability and materials compatibility characteristics of RP-1. Scanning-electron microscopic (SEM) analysis in conjunction with energy dispersive spectroscopy (EDS) were used to characterize the condition of the tube inner wall surface and any carbon deposition or corrosion formed during these runs. Results of the parametric study indicate that tests with standard RP-1 (total sulfur -23 ppm) and pure copper tubing are characterized by a depostion/deposit shedding process producing local wall temperature swings as high as 500 F. The effect of this shedding is to keep total carbon deposition levels relatively constant for run times from 20 minutes up to 5 hours, though increasing tube pressure drops were observed in all runs. Reduction in the total sulfur content of the fuel from 23 ppm to less than 0.1 ppm resulted in the elimination of deposit shedding, local wall temperature variation, and the tube pressure drop increases that were observed in standard sulfur level RP-1 tests. The copper alloy GRCop-84, a copper alloy developed specifically for high heat flux applications, was found to exhibit higher carbon deposition levels compared to identical tests performed in pure copper tubes. Results of the study are consistent with previously published heated tube data which indicates that small changes in fuel total sulfur content can lead to significant differences in the thermal stability of kerosene type fuels and their compatibility with copper based materials. In conjunction with the existing thermal stability database, these findings give insight into the feasibility of cooling a long life, high performance, high-pressure liquid rocket combustor and nozzle with RP-1.
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46 CFR 56.01-2 - Incorporation by reference.
Code of Federal Regulations, 2014 CFR
2014-10-01
...”), 56.10-5; 56.60-1; (4) ASTM A 106-95, Standard Specification for Seamless Carbon Steel Pipe for High...), Standard Specification for Seamless Carbon Steel Boiler Tubes for High-Pressure Service (“ASTM A 192”), 56... Steel Boiler and Superheater Tubes for High-Pressure Service (“ASTM A 226”), 56.60-1; (19) ASTM A 234/A...
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46 CFR 56.01-2 - Incorporation by reference.
Code of Federal Regulations, 2013 CFR
2013-10-01
...”), 56.10-5; 56.60-1; (4) ASTM A 106-95, Standard Specification for Seamless Carbon Steel Pipe for High...), Standard Specification for Seamless Carbon Steel Boiler Tubes for High-Pressure Service (“ASTM A 192”), 56... Steel Boiler and Superheater Tubes for High-Pressure Service (“ASTM A 226”), 56.60-1; (19) ASTM A 234/A...
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Trava-Airoldi, Vladimir Jesus; Capote, Gil; Bonetti, Luís Francisco; Fernandes, Jesum; Blando, Eduardo; Hübler, Roberto; Radi, Polyana Alves; Santos, Lúcia Vieira; Corat, Evaldo José
2009-06-01
A new, low cost, pulsed-DC plasma-enhanced chemical vapor deposition system that uses a bipolar, pulsed power supply was designed and tested to evaluate its capacity to produce quality diamond-like carbon films on the inner surface of steel tubes. The main focus of the study was to attain films with low friction coefficients, low total stress, a high degree of hardness, and very good adherence to the inner surface of long metallic tubes at a reasonable growth rate. In order to enhance the diamond-like carbon coating adhesion to metallic surfaces, four steps were used: (1) argon ion sputtering; (2) plasma nitriding; (3) a thin amorphous silicon interlayer deposition, using silane as the precursor gas; and (4) diamond-like carbon film deposition using methane atmosphere. This paper presents various test results as functions of the methane gas pressure and of the coaxial metal anode diameter, where the pulsed-DC voltage constant is kept constant. The influence of the coaxial metal anode diameter and of the methane gas pressure is also demonstrated. The results obtained showed the possibilities of using these DLC coatings for reduced friction and to harden inner surface of the steel tubes.
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Pollen--tiny and ephemeral but not forgotten: New ideas on their ecology and evolution.
Williams, Joseph H; Mazer, Susan J
2016-03-01
Ecologists and evolutionary biologists have been interested in the functional biology of pollen since the discovery in the 1800s that pollen grains encompass tiny plants (male gametophytes) that develop and produce sperm cells. After the discovery of double fertilization in flowering plants, botanists in the early 1900s were quick to explore the effects of temperature and maternal nutrients on pollen performance, while evolutionary biologists began studying the nature of haploid selection and pollen competition. A series of technical and theoretic developments have subsequently, but usually separately, expanded our knowledge of the nature of pollen performance and how it evolves. Today, there is a tremendous diversity of interests that touch on pollen performance, ranging from the ecological setting on the stigma, structural and physiological aspects of pollen germination and tube growth, the form of pollen competition and its role in sexual selection in plants, virus transmission, mating system evolution, and inbreeding depression. Given the explosion of technical knowledge of pollen cell biology, computer modeling, and new methods to deal with diversity in a phylogenetic context, we are now more than ever poised for a new era of research that includes complex functional traits that limit or enhance the evolution of these deceptively simple organisms. © 2016 Botanical Society of America.
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Relative optical absorption of metallic and semiconducting single-walled carbon nanotubes.
Huang, Houjin; Kajiura, Hisashi; Maruyama, Ryuichiro; Kadono, Koji; Noda, Kazuhiro
2006-03-16
While it is well-known that tube-tube interaction causes changes (peak red-shift and suppression) in the optical absorption of single-walled carbon nanotubes (SWNTs), we found in this work that, upon bundling, the optical absorption of metallic SWNTs (M11) is less affected compared to their semiconducting counterparts (S11 or S22), resulting in enhanced absorbance ratio of metallic and semiconducting SWNTs (A(M)/A(S)). Annealing of the SWNTs increases this ratio due to the intensified tube-tube interaction. We have also found that the interaction between SWNTs and the surfactant Triton X-405 has a similar effect. The evaluation of SWNT separation by types (metallic or semiconducting) based on the optical absorption should take these effects into account.
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Probing Phonon Dynamics in Individual Single-Walled Carbon Nanotubes.
Jiang, Tao; Hong, Hao; Liu, Can; Liu, Wei-Tao; Liu, Kaihui; Wu, Shiwei
2018-04-11
Interactions between elementary excitations, such as carriers, phonons, and plasmons, are critical for understanding the optical and electronic properties of materials. The significance of these interactions is more prominent in low-dimensional materials and can dominate their physical properties due to the enhanced interactions between these excitations. One-dimensional single-walled carbon nanotubes provide an ideal system for studying such interactions due to their perfect physical structures and rich electronic properties. Here we investigated G-mode phonon dynamics in individual suspended chirality-resolved single-walled carbon nanotubes by time-resolved anti-Stokes Raman spectroscopy. The improved technique allowed us to probe the intrinsic phonon information on a single-tube level and exclude the influences of tube-tube and tube-substrate interactions. We found that the G-mode phonon lifetime ranges from 0.75-2.25 ps and critically depends on whether the tube is metallic or semiconducting. In comparison with the phonon lifetimes in graphene and graphite, we revealed structure-dependent carrier-phonon and phonon-phonon interactions in nanotubes. Our results provide new information for optimizing the design of nanotube electronic/optoelectronic devices by better understanding and utilizing their phonon decay channels.
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Light-dependent microbial metabolisms drive carbon fluxes on glacier surfaces.
Franzetti, Andrea; Tagliaferri, Ilario; Gandolfi, Isabella; Bestetti, Giuseppina; Minora, Umberto; Mayer, Christoph; Azzoni, Roberto S; Diolaiuti, Guglielmina; Smiraglia, Claudio; Ambrosini, Roberto
2016-12-01
Biological processes on glacier surfaces affect glacier reflectance, influence surface energy budget and glacier response to climate warming, and determine glacier carbon exchange with the atmosphere. Currently, carbon balance of supraglacial environment is assessed as the balance between the activity of oxygenic phototrophs and the respiration rate of heterotrophic organisms. Here we present a metagenomic analysis of tiny wind-blown supraglacial sediment (cryoconite) from Baltoro (Pakistani Karakoram) and Forni (Italian Alps) glaciers, providing evidence for the occurrence in these environments of different and previously neglected metabolic pathways. Indeed, we observed high abundance of heterotrophic anoxygenic phototrophs, suggesting that light might directly supplement the energy demand of some bacterial strains allowing them to use as carbon source organic molecules, which otherwise would be respired. Furthermore, data suggest that CO 2 could be produced also by microbiologically mediated oxidation of CO, which may be produced by photodegradation of organic matter.
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Law, Justin J; Guven, Adem; Wilson, Lon J
2014-01-01
Ultrashort single-walled carbon nanotubes loaded with gadolinium ions (gadonanotubes) have been previously shown to exhibit extremely high T1 -weighted relaxivities (>100 mm(-1) s(-1) ). To further examine the effect of nanoconfinement on the relaxivity of gadolinium-based contrast agents for magnetic resonance imaging, a series of ultrashort single-walled carbon nanotube (US-tube) materials internally loaded with gadolinium chelates have been prepared and studied. US-tubes were loaded with Gd(acac)3 · 2H2 O, Gd(hfac)3 · 2H2 O, and Gd(thd)3 (acac = acetylacetone, hfac = hexafluoroacetylacetone, thd = tetramethylheptanedione). The longitudinal relaxivities of the prepared materials determined at 25°C in a 1.5 T field were 103 mm(-1) s(-1) for Gd(acac)3 · 2H2 O@US-tubes, 105 mm(-1) s(-1) for Gd(hfac)3 · 2H2 O@US-tubes and 26 mm(-1) s(-1) for Gd(thd)3 @US-tubes. Compared with the relaxivities obtained for the unloaded chelates (<10 mm(-1) s(-1) ) as well as accounting for the T1 reduction observed for the empty US-tubes, the boost in relaxivity for chelate-loaded US-tubes is attributed to confinement within the nanotube and depends on the number of coordinated water molecules. Copyright © 2014 John Wiley & Sons, Ltd.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Grigorian, G. M.; Dyatko, N. A.; Kochetov, I. V., E-mail: kochet@triniti.ru
Radial profiles of the density of metastable atoms Ar({sup 3}P{sub 2}) in the positive column of a dc glow discharge in argon were measured. Gas-discharge glass tubes with clean inner surfaces and surfaces covered with a carbonitride or carbon film were utilized. The parameters of the discharge plasma under experimental conditions were calculated in the framework of a one-dimensional (along the tube radius) discharge model. The coefficient K of reflection of Ar({sup 3}P{sub 2}) atoms from the tube wall was estimated by comparing the measured and calculated density profiles. It is found that, for a clean tube wall, the coefficientmore » of reflection is K = 0.4 ± 0.2, whereas for a wall covered with a carbonitride or carbon film, it is K < 0.2.« less
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Conduction properties of thin films from a water soluble carbon nanotube/hemicellulose complex
NASA Astrophysics Data System (ADS)
Shao, Dongkai; Yotprayoonsak, Peerapong; Saunajoki, Ville; Ahlskog, Markus; Virtanen, Jorma; Kangas, Veijo; Volodin, Alexander; Van Haesendonck, Chris; Burdanova, Maria; Mosley, Connor D. W.; Lloyd-Hughes, James
2018-04-01
We have examined the conductive properties of carbon nanotube based thin films, which were prepared via dispersion in water by non-covalent functionalization of the nanotubes with xylan, a type of hemicellulose. Measurements of low temperature conductivity, Kelvin probe force microscopy, and high frequency (THz) conductivity elucidated the intra-tube and inter-tube charge transport processes in this material. The measurements show excellent conductive properties of the as prepared thin films, with bulk conductivity up to 2000 S cm-1. The transport results demonstrate that the hemicellulose does not seriously interfere with the inter-tube conductance.
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NASA Astrophysics Data System (ADS)
Zhu, Chengzhang; Gong, Tingting; Xian, Qiming; Xie, Jimin
2018-06-01
Novel well-dispersed tiny Bi2S3 nanoparticles (NPs) with an average sizes of approximately 16.2 nm were used to decorate layered g-C3N4 nanosheets (NSs), with the purpose of constructing highly efficient 0D/2D heterojunction photocatalyst by a simple hydrothermal method in one step. The fabricated Bi2S3/g-C3N4 heterostructures exhibited superior visible-light-driven photocatalytic activity toward methyl orange (MO) degradation in contrast to that of individual Bi2S3 and g-C3N4, which could be mainly ascribed to the synergistic effect of the tiny size effect of 0D Bi2S3 NPs and 2D g-C3N4 NSs, the matched energy level positions, and the abundant coupling heterointerfaces between two moieties. More importantly, the photodegradation of methylene blue (MB), rhodamine B (RhB) and colorless tetracycline (TC), ciprofloxacin (CIP) further revealed the broad-spectrum photodegradation capacities of the heterojunction materials. The possible photoinduced charge transfer and pollutant degradation process over Bi2S3/g-C3N4 heterojunctions under visible-light irradiation were proposed. This work may provide a platform for constructing new visible light 0D/2D intimate contact heterostructures with stable and efficient photocatalytic performance.
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Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon
NASA Technical Reports Server (NTRS)
Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.
2012-01-01
The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.
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Carbon granule probe microphone for leak detection. [recovery boilers
NASA Technical Reports Server (NTRS)
Parthasarathy, S. P. (Inventor)
1985-01-01
A microphone which is not subject to corrosion is provided by employing carbon granules to sense sound waves. The granules are packed into a ceramic tube and no diaphragm is used. A pair of electrodes is located in the tube adjacent the carbon granules and are coupled to a sensing circuit. Sound waves cause pressure changes on the carbon granules which results in a change in resistance in the electrical path between the electrodes. This change in resistance is detected by the sensing circuit. The microphone is suitable for use as a leak detection probe in recovery boilers, where it provides reliable operation without corrosion problems associated with conventional microphones.
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Permeability of nanonet structures constructed on the basis of carbon tubes
NASA Astrophysics Data System (ADS)
Bubenchikov, M. A.; Nikipelova, T. I.; Tsyrenova, V. B.; Chelnokova, A. S.
2017-11-01
An approximate integration of a potential of paired molecular interactions over the circumferential coordinate is used to find the potential of the interaction between a molecule and an infinite carbon nanotube (CNT). Based on the obtained energy of interaction between the tube and the molecules, local effective radii of the investigated carbon structures with respect to the molecules of the separated gas mixture are found. This makes it possible to calculate permeability of a single-layer, along with a two-layer CNT packing. The conducted research allowed calculating permeability of a nanonet structure as permeability of a two-layer packing of carbon nanotubes for the first time.
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Small-Scale Production of High-Density Dry Ice: A Variant Combination of Two Classic Demonstrations
ERIC Educational Resources Information Center
Flowers, Paul A.
2009-01-01
Easily recoverable, thumb-sized pieces of high-density dry ice are conveniently produced by deposition of carbon dioxide within a test tube submerged in liquid nitrogen. A carbon dioxide-filled balloon sealed over the mouth of the test tube serves as a gas reservoir, and further permits a dramatic demonstration of both the gas-to-solid phase…
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Identification of Aircraft Tubing by Rockwell Test
NASA Technical Reports Server (NTRS)
Knerr, Horace C.
1930-01-01
Seamless steel tubing is today the principal material of construction for aircraft. The commercial grade of tubing containing about 0.10 to 0.20% carbon at first used is being superseded by two grades which are approved by the army and navy, and which are also becoming standard for commercial airplanes.
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Pistons and Cylinders Made of Carbon-Carbon Composite Materials
NASA Technical Reports Server (NTRS)
Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)
2000-01-01
An improved reciprocating internal combustion engine has a plurality of engine pistons, which are fabricated from carbon-carbon composite materials, in operative association with an engine cylinder block, or an engine cylinder tube, or an engine cylinder jug, all of which are also fabricated from carbon-carbon composite materials.
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Effective Removal of Tetracycline Antibiotics from Water using Hybrid Carbon Membranes
NASA Astrophysics Data System (ADS)
Liu, Ming-Kai; Liu, Ying-Ya; Bao, Dan-Dan; Zhu, Gen; Yang, Guo-Hai; Geng, Jun-Feng; Li, Hai-Tao
2017-03-01
Antibiotic residues in drinking water have become a global problem, especially in developing countries. However, effective purification of water contaminated by antibiotics remains a great challenge. Here, we investigated the removing of tetracycline by carbon nanomaterials with different structures and surface functionalities. The result shows that a membrane of thick graphene oxide (GO) and activated carbon (AC) with a thickness of 15 μm can effectively remove 98.9% of tetracycline hydrochloride (TCH) from water by vacuum filtration. Structural analysis indicated that the AC nanoparticles were uniformly inserted into the GO interstitial sites without any aggregations. Also, GO sheets were loosened by the encapsulated AC nanoparticles, leading to the formation of numerous tiny pores (3-10 nm) that acted as channels for fluid passage, whereas the carbons and chemical groups on the GO surface adsorbed TCH. GO/AC membrane exhibits the best adsorption efficiency among the investigated materials, including pure GO, AC, carbon nanotube (CNT), and CNT/AC and GO/CNT hybrids.
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Tiny tiny things with an amazing power
NASA Astrophysics Data System (ADS)
McCammon, C. A.; Peiffer, S.; Wan, M.
2017-12-01
Our world is made of tiny tiny things that come together to make bigger things. Some of these tiny tiny things have an amazing power and can change themselves in air, the same way that old cars grow spots made up of small red bits. But when our world was very young, these tiny tiny things with the amazing power could not change to small red bits because the air was different. How was it different? For one thing it did not have the stuff that animals need to breathe. But things were not boring on our very young world and much was happening that would eventually change the air so that animals could breathe. We studied some of the stuff that changed during the growing up of our world using strong light that makes funny forms. We learned many new things and that changes happen slowly in water but faster when stuff is dry.
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Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid
NASA Technical Reports Server (NTRS)
Juhasz, Albert J.
2010-01-01
This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).
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Kulshrestha, Neha; Misra, Abhishek; Hazra, Kiran Shankar; Roy, Soumyendu; Bajpai, Reeti; Mohapatra, Dipti Ranjan; Misra, D S
2011-03-22
We report the healing of electrically broken multiwalled carbon nanotubes (MWNTs) using very low energy electrons (3-10 keV) in scanning electron microscopy (SEM). Current-induced breakdown caused by Joule heating has been achieved by applying suitably high voltages. The broken tubes were examined and exposed to electrons of 3-10 keV in situ in SEM with careful maneuvering of the electron beam at the broken site, which results in the mechanical joining of the tube. Electrical recovery of the same tube has been confirmed by performing the current-voltage measurements after joining. This easy approach is directly applicable for the repairing of carbon nanotubes incorporated in ready devices, such as in on-chip horizontal interconnects or on-tip probing applications, such as in scanning tunneling microscopy.
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Coated woven materials and method of preparation
McCreary, W.J.; Carroll, D.W.
Coating of woven materials so that not only the outer surfaces are coated has been a problem. Now, a solution to that problem is by coating with materials, with metals or with pyrolytic carbon. Materials are deposited in Chemical Vapor Deposition (CND) reactions using a fluidized bed so that the porosity of the woven materials is retained and the tiny filaments which make up the strands which are woven (including inner as well as outer filaments) are substantially uniformly coated.
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A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS
DOE Office of Scientific and Technical Information (OSTI.GOV)
Valluri, Monica; Abbott, Caleb; Shen, Juntai
We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotatingmore » triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.« less
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Code of Federal Regulations, 2014 CFR
2014-10-01
... standards ASME standards Notes Pipe, seamless: A 106 Carbon steel ASME B31.1 A 335 Ferritic alloys ASME B31.1 A 376 Austenitic alloys ASME B31.1 (1). Pipe, seamless and welded: A 53 Types S, F, and E steel... cast: (None applicable) (1 9) Tube, seamless: A 179 Carbon steel heat exchanger and condenser tubes...
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Code of Federal Regulations, 2013 CFR
2013-10-01
... standards ASME standards Notes Pipe, seamless: A 106 Carbon steel ASME B31.1 A 335 Ferritic alloys ASME B31.1 A 376 Austenitic alloys ASME B31.1 (1). Pipe, seamless and welded: A 53 Types S, F, and E steel... cast: (None applicable) (1 9) Tube, seamless: A 179 Carbon steel heat exchanger and condenser tubes...
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Code of Federal Regulations, 2012 CFR
2012-10-01
... standards ASME standards Notes Pipe, seamless: A 106 Carbon steel ASME B31.1 A 335 Ferritic alloys ASME B31.1 A 376 Austenitic alloys ASME B31.1 (1). Pipe, seamless and welded: A 53 Types S, F, and E steel... cast: (None applicable) (1,9) Tube, seamless: A 179 Carbon steel heat exchanger and condenser tubes...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-05-03
.../10 India: Silicomanganese, A-533-823 5/1/09-4/30/10 Welded Carbon Steel Pipe and Tubes, A-533-502.../30/10 Republic of Korea: Polyester Staple Fiber, A-580-839 5/1/09-4/30/10 Stainless Steel Plate in.../10 805 Taiwan: Certain Circular Welded Carbon Steel Pipe and 5/1/09-4/30/10 Tubes, A-583-008...
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Carbon Nanotube Anodes Being Evaluated for Lithium Ion Batteries
NASA Technical Reports Server (NTRS)
Raffaelle, Ryne P.; Gennett, Tom; VanderWal, Randy L.; Hepp, Aloysius F.
2001-01-01
The NASA Glenn Research Center is evaluating the use of carbon nanotubes as anode materials for thin-film lithium-ion (Li) batteries. The motivation for this work lies in the fact that, in contrast to carbon black, directed structured nanotubes and nanofibers offer a superior intercalation media for Li-ion batteries. Carbon lamellas in carbon blacks are circumferentially oriented and block much of the particle interior, rendering much of the matrix useless as intercalation material. Nanofibers, on the other hand, can be grown so as to provide 100-percent accessibility of the entire carbon structure to intercalation. These tubes can be visualized as "rolled-up" sheets of carbon hexagons (see the following figure). One tube is approximately 1/10,000th the diameter of a human hair. In addition, the high accessibility of the structure confers a high mobility to ion-exchange processes, a fundamental for the batteries to respond dynamically because of intercalation.
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NASA Technical Reports Server (NTRS)
O'Brien, T. Kevin; Czabaj, Michael W.; Hinkley, Jeffrey A.; Tsampas, Spiros; Greenhalgh, Emile S.; McCombe, Gregory; Bond, Ian P.; Trask, Richard
2013-01-01
A study was undertaken to develop a prototype method for adding through-thickness hollow glass tubes infused with uncured resin and hardener in a carbon Z-pin through-thickness reinforcement field embedded in a composite laminate. Two types of tube insertion techniques were attempted in an effort to ensure the glass tubes survived the panel manufacturing process. A self-healing resin was chosen with a very low viscosity, two component, liquid epoxy resin system designed to be mixed at a 2-to-1 ratio of epoxy to hardener. IM7/8552 carbon epoxy double cantilever beam (DCB) specimens were cut from the hybrid Z-pin and glass tube reinforced panels and tested. In-situ injection of resin and hardener directly into glass tubes, in a staggered pattern to allow for 2-to-1 ratio mixing, resulted in partial healing of the fracture plane, but only if the injection was performed while the specimen was held at maximum load after initial fracture. Hence, there is some potential for healing delamination via resin and hardener delivered through a network of through-thickness glass tubes, but only if the tubes are connected to a reservoir where additional material may be injected as needed.
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Hunt, Arlon J.
1984-01-01
A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.
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Hunt, A.J.
1982-09-29
A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.
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Del Mar, Peter
1995-01-01
A process of sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium by (a) passing an initial aqueous medium including a minor amount of the organic contaminant through a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit the organic contaminant to adhere to the composite tube, (b) passing a solvent through the composite tube, said solvent capable of separating the adhered organic contaminant from the composite tube. Further, an extraction apparatus for sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium, said apparatus including a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit an organic contaminant contained within an aqueous medium passed therethrough to adhere to the composite tube is disclosed.
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Mar, Peter D.
1994-01-01
A process of sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium by (a) passing an initial aqueous medium including a minor amount of the organic contaminant through a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit the organic contaminant to adhere to the composite tube, (b) passing a solvent through the composite tube, said solvent capable of separating the adhered organic contaminant from the composite tube. Further, an extraction apparatus for sample preparation prior to analysis for the concentration of an organic contaminant in an aqueous medium, said apparatus including a composite tube including a polymeric base material selected from the group of polyolefins and polyfluorocarbons and particles of a carbon allotrope material adfixed to the inner wall of the polymeric base material, the composite tube having an internal diameter of from about 0.1 to about 2.0 millimeters and being of sufficient length to permit an organic contaminant contained within an aqueous medium passed therethrough to adhere to the composite tube is disclosed.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-09-06
... DEPARTMENT OF COMMERCE International Trade Administration [A-201-836] Light-Walled Rectangular... the antidumping duty order on light-walled rectangular pipe and tube (LWR pipe and tube) from Mexico... The merchandise subject to the order is certain welded carbon- quality light-walled steel pipe and...
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A vacuum-sealed compact x-ray tube based on focused carbon nanotube field-emission electrons
NASA Astrophysics Data System (ADS)
Jeong, Jin-Woo; Kim, Jae-Woo; Kang, Jun-Tae; Choi, Sungyoul; Ahn, Seungjoon; Song, Yoon-Ho
2013-03-01
We report on a fully vacuum-sealed compact x-ray tube based on focused carbon nanotube (CNT) field-emission electrons for various radiography applications. The specially designed two-step brazing process enabled us to accomplish a good vacuum level for the stable and reliable operation of the x-ray tube without any active vacuum pump. Also, the integrated focusing electrodes in the field-emission electron gun focused electron beams from the CNT emitters onto the anode target effectively, giving a small focal spot of around 0.3 mm with a large current of above 50 mA. The active-current control through the cathode electrode of the x-ray tube led a fast digital modulation of x-ray dose with a low voltage of below 5 V. The fabricated compact x-ray tube showed a stable and reliable operation, indicating good maintenance of a vacuum level of below 5 × 10-6 Torr and the possibility of field-emission x-ray tubes in a stand-alone device without an active pumping system.
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The hummingbird tongue is a fluid trap, not a capillary tube
Rico-Guevara, Alejandro; Rubega, Margaret A.
2011-01-01
Hummingbird tongues pick up a liquid, calorie-dense food that cannot be grasped, a physical challenge that has long inspired the study of nectar-transport mechanics. Existing biophysical models predict optimal hummingbird foraging on the basis of equations that assume that fluid rises through the tongue in the same way as through capillary tubes. We demonstrate that the hummingbird tongue does not function like a pair of tiny, static tubes drawing up floral nectar via capillary action. Instead, we show that the tongue tip is a dynamic liquid-trapping device that changes configuration and shape dramatically as it moves in and out of fluids. We also show that the tongue–fluid interactions are identical in both living and dead birds, demonstrating that this mechanism is a function of the tongue structure itself, and therefore highly efficient because no energy expenditure by the bird is required to drive the opening and closing of the trap. Our results rule out previous conclusions from capillarity-based models of nectar feeding and highlight the necessity of developing a new biophysical model for nectar intake in hummingbirds. Our findings have ramifications for the study of feeding mechanics in other nectarivorous birds, and for the understanding of the evolution of nectarivory in general. We propose a conceptual mechanical explanation for this unique fluid-trapping capacity, with far-reaching practical applications (e.g., biomimetics). PMID:21536916
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The hummingbird tongue is a fluid trap, not a capillary tube.
Rico-Guevara, Alejandro; Rubega, Margaret A
2011-06-07
Hummingbird tongues pick up a liquid, calorie-dense food that cannot be grasped, a physical challenge that has long inspired the study of nectar-transport mechanics. Existing biophysical models predict optimal hummingbird foraging on the basis of equations that assume that fluid rises through the tongue in the same way as through capillary tubes. We demonstrate that the hummingbird tongue does not function like a pair of tiny, static tubes drawing up floral nectar via capillary action. Instead, we show that the tongue tip is a dynamic liquid-trapping device that changes configuration and shape dramatically as it moves in and out of fluids. We also show that the tongue-fluid interactions are identical in both living and dead birds, demonstrating that this mechanism is a function of the tongue structure itself, and therefore highly efficient because no energy expenditure by the bird is required to drive the opening and closing of the trap. Our results rule out previous conclusions from capillarity-based models of nectar feeding and highlight the necessity of developing a new biophysical model for nectar intake in hummingbirds. Our findings have ramifications for the study of feeding mechanics in other nectarivorous birds, and for the understanding of the evolution of nectarivory in general. We propose a conceptual mechanical explanation for this unique fluid-trapping capacity, with far-reaching practical applications (e.g., biomimetics).
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Laser Processing of Carbon Nanotube Transparent Conducting Films
NASA Astrophysics Data System (ADS)
Mann, Andrew
Transparent conducting films, or TCFs, are 2D electrical conductors with the ability to transmit light. Because of this, they are used in many popular electronics including smart phones, tablets, solar panels, and televisions. The most common material used as a TCF is indium tin oxide, or ITO. Although ITO has great electrical and optical characteristics, it is expensive, brittle, and difficult to pattern. These limitations have led researchers toward other materials for the next generation of displays and touch panels. The most promising material for next generation TCFs is carbon nanotubes, or CNTs. CNTs are cylindrical tubes of carbon no more than a few atoms thick. They have different electrical and optical properties depending on their atomic structure, and are extremely strong. As an electrode, they conduct electricity through an array of randomly dispersed tubes. The array is highly transparent because of gaps between the tubes, and size and optical properties of the CNTs. Many research groups have tried making CNT TCFs with opto-electric properties similar to ITO but have difficultly achieving high conductivity. This is partly attributed to impurities from fabrication and a mix of different tube types, but is mainly caused by low junction conductivity. In functionalized nanotubes, junction conductivity is impaired by covalently bonded molecules added to the sidewalls of the tubes. The addition of this molecule, known as functionalization, is designed to facilitate CNT dispersion in a solvent by adding properties of the molecule to the CNTs. While necessary for a good solution, functionalization decreases the conductivity in the CNT array by creating defects in the tube's structures and preventing direct inter-carbon bonding. This research investigates removing the functional coating (after tube deposition) by laser processing. Laser light is able to preferentially heat the CNTs because of their optical and electrical properties. Through local conduction, the relatively weak functional molecules are thermally decomposed. This restores the pristine CNT structure and allows carbon to carbon bonds to form; thereby significantly improving the junction and sheet conductivity. Laser processing is performed without damaging the TCF substrate (usually glass or PET) because laser light is not absorbed by the substrate and conduction from the CNTs is limited. In addition to removing the functional coating, laser light improves the electrical conductivity by purifying the CNT array. The purity is improved through the ablation of defective tubes and amorphous carbon in the CNT film.[1] Using higher laser power, it is possible to locally remove the CNTs. Selective laser removal of the CNTs is a dry process that can be used to pattern the electrode. This is a much simpler and less expensive patterning technique than wet acid etching used for ITO. In summary, laser processing of CNT TCFs is shown to improve the electrical conductivity by defunctionalizing the CNTs. In addition, laser exposure increases purity by removing defects and can be used to pattern the electrode. These advances make CNTs more competitive as an alternative for ITO which has both cost and performance limitations. [1] T. Ueda, S. K. (2008). Effect of laser irradiation on carbon nanotube films for NOx gas sensor. Surface & Coatings Technology, 202, 5325--5328.
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Synthesis and Electronic Transport in Single-Walled Carbon Nanotubes of Known Chirality
NASA Astrophysics Data System (ADS)
Caldwell, Robert Victor
Since their discovery in 1991, carbon nanotubes have proven to be a very interesting material for its physical strength, originating from the pure carbon lattice and strong covalent sp2 orbital bonds, and electronic properties which are derived from the lattice structure lending itself to either a metallic or semiconducting nature among its other properties. Carbon nanotubes have been researched with an eye towards industry applications ranging from use as an alloy in metals and plastics to improve physical strength of the resulting materials to uses in the semiconductor industry as either an interconnect or device layer for computer chips to chemical or biological sensors. This thesis focuses on both the synthesis of individual single-walled carbon nanotubes as well as the electrical properties of those tubes. What makes the work herein different from that of other thesis is that the research has been performed on carbon nanotubes of known chirality. Having first grown carbon nanotubes with a chemical vapor deposition growth in a quartz tube using ethanol vapor as a feedstock to grow long individual single-walled carbon nanotubes on a silicon chip that is also compatible with Rayleigh scattering spectroscopy to identify the chiral indices of the carbon nanotubes in question, those tubes were then transferred with a mechanical transfer process specially designed in our research lab onto a substrate of our choosing before an electrical device was made out of those tubes using standard electron beam lithography. The focus in this thesis is on the work that went into designing and testing this process as well as the initial results of the electronic properties of those carbon nanotubes of known chirality, such as the first known electrical measurements on single individual armchair carbon nanotubes as well as the first known electrical measurements of a single semiconducting carbon nanotube on thin hexagonal boron nitride to study the effects of the surface optical phonons from the boron nitride on the electrical properties of the carbon nanotube. Finally a few research projects are discussed in which carbon nanotubes of known chirality were used in conjunction with first electrical tests on molecules, secondly on a prefabricated complementary metal-oxide-semiconductor integrated circuit as an inverter and lastly to study the photoconductivity generated by a synchrotron laser source to identify the values for the low energy excitonic peak.
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Sampling Artifacts from Conductive Silicone Tubing
DOE Office of Scientific and Technical Information (OSTI.GOV)
Timko, Michael T.; Yu, Zhenhong; Kroll, Jesse
2009-05-15
We report evidence that carbon impregnated conductive silicone tubing used in aerosol sampling systems can introduce two types of experimental artifacts: 1) silicon tubing dynamically absorbs carbon dioxide gas, requiring greater than 5 minutes to reach equilibrium and 2) silicone tubing emits organic contaminants containing siloxane that adsorb onto particles traveling through it and onto downstream quartz fiber filters. The consequence can be substantial for engine exhaust measurements as both artifacts directly impact calculations of particulate mass-based emission indices. The emission of contaminants from the silicone tubing can result in overestimation of organic particle mass concentrations based on real-time aerosolmore » mass spectrometry and the off-line thermal analysis of quartz filters. The adsorption of siloxane contaminants can affect the surface properties of aerosol particles; we observed a marked reduction in the water-affinity of soot particles passed through conductive silicone tubing. These combined observations suggest that the silicone tubing artifacts may have wide consequence for the aerosol community and should, therefore, be used with caution. Gentle heating, physical and chemical properties of the particle carriers, exposure to solvents, and tubing age may influence siloxane uptake. The amount of contamination is expected to increase as the tubing surface area increases and as the particle surface area increases. The effect is observed at ambient temperature and enhanced by mild heating (<100 oC). Further evaluation is warranted.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Mitchell, G.; Davis, A.; Burke, F.P.
1991-12-01
This study demonstrated the use of the gold tube carbonization technique and reflectance microscopy analysis for the examination of process-derived materials from direct coal liquefaction. The carbonization technique, which was applied to coal liquefaction distillation resids, yields information on the amounts of gas plus distillate, pyridine-soluble resid, and pyridine-insoluble material formed when a coal liquid sample is heated to 450{degree}C for one hour at 5000 psi in an inert atmosphere. The pyridine-insolubles then are examined by reflectance microscopy to determine the type, amount, and optical texture of isotropic and anisotropic carbon formed upon carbonization. Further development of these analytical methodsmore » as process development tools may be justified on the basis of these results.« less
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Process Produces Low-Secondary-Electron-Emission Surfaces
NASA Technical Reports Server (NTRS)
Curren, A. N.; Jensen, K. A.; Roman, R. F.
1986-01-01
Textured carbon layer applied to copper by sputtering. Carbon surface characterized by dense, random array of needle-like spires or peaks that extend perpendicularly from local copper surface. Spires approximately 7 micrometers in height and spaced approximately 3 micrometers apart, on average. Copper substrate essentially completely covered by carbon layer, is tenacious and not damaged by vibration loadings representative of multistage depressed collector (MDC) applications. Process developed primarily to provide extremely low-secondary-electron-emission surface for copper for use as highefficiency electrodes in MDC's for microwave amplifier traveling-wave tubes (TWT's). Tubes widely used in space communications, aircraft, and terrestrial applications.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ren, Wei, E-mail: wei.ren@helsinki.fi; Avchaciov, Konstantin; Nordlund, Kai
Carbon nanotubes are of wide interest due to their excellent properties such as tensile strength and electrical and thermal conductivity, but are not, when placed alone on a substrate, well resistant to mechanical wear. Diamond-like carbon (DLC), on the other hand, is widely used in applications due to its very good wear resistance. Combining the two materials could provide a very durable pure carbon nanomaterial enabling to benefit from the best properties of both carbon allotropes. However, the synthesis of high-quality diamond-like carbon uses energetic plasmas, which can damage the nanotubes. From previous works it is neither clear whether themore » quality of the tubes remains good after DLC deposition, nor whether the DLC above the tubes retains the high sp{sup 3} bonding fraction. In this work, we use experiments and classical molecular dynamics simulations to study the mechanisms of DLC formation on various carbon nanotube compositions. The results show that high-sp{sup 3}-content DLC can be formed provided the deposition conditions allow for sidewards pressure to form from a substrate close beneath the tubes. Under optimal DLC formation energies of around 40–70 eV, the top two nanotube atom layers are fully destroyed by the plasma deposition, but layers below this can retain their structural integrity.« less
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Experimental Study on Flow Boiling of Carbon Dioxide in a Horizontal Microfin Tube
NASA Astrophysics Data System (ADS)
Kuwahara, Ken; Ikeda, Soshi; Koyama, Shigeru
This paper deals with the experimental study on flow boiling heat transfer of carbon dioxide in a micro-fin tube. The geometrical parameters of micro-fin tube used in this study are 6.07 mm in outer diameter, 5.24 mm in average inner diameter, 0.256 mm in fin height, 20.4 in helix angle, 52 in number of grooves and 2.35 in area expansion ratio. Flow patterns and heat transfer coefficients were measured at 3-5 MPa in pressure, 300-540 kg/(m2s) in mass velocity and -5 to 15 °C in CO2 temperature. Flow patterns of wavy flow, slug flow and annular flow were observed. The measured heat transfer coefficients of micro-fin tube were 10-40 kW/(m2K). Heat transfer coefficients were strongly influenced by pressure.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-05-01
......... 5/1/11-9/14/11 India: Silicomanganese, A-533-823 5/1/11-4/30/12 Welded Carbon Steel Pipes and Tubes... of Korea: Polyester Staple Fiber, A-580-839 5/1/11-4/30/12 Stainless Steel Plate in Coils, A-580-831...: Circular Welded Carbon Steel Pipes and Tubes, A- 5/1/11-4/30/12 583-008 Polyethylene Retail Carrier Bags, A...
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DFT study of Al doped armchair SWCNTs
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dhiman, Shobhna, E-mail: s-dhiman@hotmail.com; Rani, Anita; Kumar, Ranjan
2016-05-23
Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This showsmore » that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).« less
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Kamada, T
The extraction behaviour of arsenic(III) and arsenic(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone in organic solvents has been investigated by means of nameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of arsenic(III) and differential determination of arsenic(III) and arsenic(V) have been developed. With ammonium pyrrolidinedithiocarbamate and methyl isobutyl ketone or nitrobenzene, when the aqueous phase/solvent volume ratio is 5 and the injection volume in the carbon tube is 20 mul, the sensitivities for 1% absorption are 0.4 and 0.5 part per milliard of arsenic, respectively. The relative standard deviations are ca. 3%. Interference by many metal ions can be prevented by masking with EDTA. The proposed methods are applied satisfactorily for determination of As(III) and As(V) in various types of water.
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Flow-Tube Reactor Experiments on the High Temperature Oxidation of Carbon Weaves
NASA Technical Reports Server (NTRS)
Panerai, Francesco; White, Jason D.; Robertson, Robert; Borner, Arnaud; Ferguson, Joseph C.; Mansour, Nagi N.
2017-01-01
Under entry conditions carbon weaves used in thermal protection systems (TPS) decompose via oxidation. Modeling this phenomenon is challenging due to the different regimes encountered along a flight trajectory. Approaches using equilibrium chemistry may lead to over-estimated mass loss and recession at certain conditions. Concurrently, there is a shortcoming of experimental data on carbon weaves to enable development of improved models. In this work, a flow-tube test facility was used to measure the oxidation of carbon weaves at temperatures up to 1500 K. The material tested was the 3D carbon weave used for the heat shield of the NASA Adaptive Deployable Entry and Placement Technology, ADEPT. Oxidation was characterized by quantifying decomposition gases (CO and CO2), by mass measurements, and by microscale surface analysis. The current set of measurements contributes to the development of finite rate chemistry models for carbon fabrics used in woven TPS materials.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-10-24
...-534, and 536 (Third Review)] Certain Pipe and Tube From Brazil, India, Korea, Mexico, Taiwan, Thailand... Turkey, the antidumping duty orders on welded carbon steel pipe and tube from India, Thailand, and Turkey... group responses with respect to Mexico, Thailand, and Turkey were adequate, and decided to conduct full...
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-22
... of the Government of the UAE's (``GUAE''), Universal Tube and Plastic Industries, Ltd., KHK... forth above, and also has one or more of the following characteristics: Is 32 feet in length or less; is... Universal Tube and Plastic Industries, Ltd.; KHK 2.06 Scaffolding and Formwork LLC; Universal Tube and Pipe...
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Formation and Combustion of Smoke in Laminar Flames
NASA Technical Reports Server (NTRS)
Schalla, Rose L; Clark, Thomas P; Mcdonald, Glen E
1954-01-01
The nature and formation of smoke and its combustion were investigated. Smoke, which consist of tiny mesomorphous crystals tightly packed into popcorn-ball-like particles that agglomerate to give filaments, was found to contain about 5 percent of the hydrogen originally present in the fuel. Factors affecting smoke formation were studied in both diffusion flames and premixed Bunsen flames. It is suggested that smoking tendency increases with increasing stability of the carbon skeleton of the molecule, as determined by relative bond strength.
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Occupational Exposure to Carbon Nanotubes and Nanofibers
... Software Video Follow NIOSH Facebook Flickr Pinterest Twitter YouTube NIOSH Homepage NIOSH A-Z Workplace Safety & Health ... Review Plan Follow NIOSH Facebook Flickr Pinterest Twitter YouTube NIOSH Homepage NIOSH A-Z Workplace Safety & Health ...
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Mechanics of low-dimensional carbon nanostructures: Atomistic, continuum, and multi-scale approaches
NASA Astrophysics Data System (ADS)
Mahdavi, Arash
A new multiscale modeling technique called the Consistent Atomic-scale Finite Element (CAFE) method is introduced. Unlike traditional approaches for linking the atomic structure to its equivalent continuum, this method directly connects the atomic degrees of freedom to a reduced set of finite element degrees of freedom without passing through an intermediate homogenized continuum. As a result, there is no need to introduce stress and strain measures at the atomic level. The Tersoff-Brenner interatomic potential is used to calculate the consistent tangent stiffness matrix of the structure. In this finite element formulation, all local and non-local interactions between carbon atoms are taken into account using overlapping finite elements. In addition, a consistent hierarchical finite element modeling technique is developed for adaptively coarsening and refining the mesh over different parts of the model. This process is consistent with the underlying atomic structure and, by refining the mesh to the scale of atomic spacing, molecular dynamic results can be recovered. This method is valid across the scales and can be used to concurrently model atomistic and continuum phenomena so, in contrast with most other multi-scale methods, there is no need to introduce artificial boundaries for coupling atomistic and continuum regions. Effect of the length scale of the nanostructure is also included in the model by building the hierarchy of elements from bottom up using a finite size atom cluster as the building block. To be consistent with the bravais multi-lattice structure of sp2-bonded carbon, two independent displacement fields are used for reducing the order of the model. Sparse structure of the stiffness matrix of these nanostructures is exploited to reduce the memory requirement and to speed up the formation of the system matrices and solution of the equilibrium equations. Applicability of the method is shown with several examples of the nonlinear mechanics of carbon nanotubes and carbon nanocones subject to different loadings and boundary conditions. This finite element technique is also used to study the natural frequencies of low-dimensional carbon nanostructures and comparing the results with those of a homogenized isotropic continuum shell. Conclusion is that, replacing the atomic lattice with an isotropic continuum shell for a graphene sheet does not significantly affect the vibration frequencies while in the case of carbon nanotubes and carbon nanocones there is a significant difference between the natural frequencies of the atomistic model and its continuum counterpart. In the case of the carbon nanotube, continuum model successfully captures the beam bending vibration modes while overestimating frequencies of the modes in which the cross-section undergoes significant deformation. Furthermore, in the case of carbon nanotubes, the continuum shell exhibits a torsional mode which appears to be an artifact resulting from the small nominal thickness typically used in the continuum shell approximation of these nanostructures. Results of this study indicate that isotropic continuum shell models, while simple and useful in static analysis, cannot accurately predict the vibration frequencies of these nanostructures. We have studied the bistable nature of single-walled carbon nanotubes by investigating the change in the tube's energy as it is compressed between flat rigid indenters of various widths. Assuming the nanotube deformed uniformly along its length and modeling the cross-section as an inextensible, non-linear beam we found that tubes with a radius greater than 12 A are bistable and that tubes with a radius greater than 25 A have a lower energy in the collapsed state than in the inflated state. The difference in energy between the collapsed and inflated states decreases nearly linearly with increasing tube radius. While the inflated state remains stable for tubes of all diameters, the energy barrier keeping the tube from collapsing approaches zero as the tube radius increases. We also demonstrate why collapse with a wide indenter may be difficult to observe in narrow tubes. A reduced-order model is developed for the dynamics of the carbon nanotube atomic force microscope probes. Bending behavior of the nanotube probe is modeled using Euler's elastica. A nonlinear moment-curvature relationship is implemeneted to account for the ovalization of the cross section of the nanotube during bending. Van der Waal forces acting between tube and the substrate is integrated over the surface of the tube and used as distributed follower forces acting on the equivalent elastica. Approximating the behavior of the nanotube with an elastica proved to be a very effiecient technique for modeling these nanostructures.
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Esrafili, Mehdi D; Behzadi, Hadi
2013-06-01
A density functional theory study was carried out to predict the electrostatic potentials as well as average local ionization energies on both the outer and the inner surfaces of carbon, boron-nitride (BN), boron-phosphide (BP) and silicon-carbide (SiC) single-walled nanotubes. For each nanotube, the effect of tube radius on the surface potentials and calculated average local ionization energies was investigated. It is found that SiC and BN nanotubes have much stronger and more variable surface potentials than do carbon and BP nanotubes. For the SiC, BN and BP nanotubes, there are characteristic patterns of positive and negative sites on the outer lateral surfaces. On the other hand, a general feature of all of the systems studied is that stronger potentials are associated with regions of higher curvature. According to the evaluated surface electrostatic potentials, it is concluded that, for the narrowest tubes, the water solubility of BN tubes is slightly greater than that of SiC followed by carbon and BP nanotubes.
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Lee, Pyung -Soo; Bhave, Ramesh R.; Nam, Seung -Eun; ...
2016-01-11
Thin carbon molecular sieve membranes (<500 nm) were fabricated inside of long geometry (9 inch) of stainless steel tubes with all welded construction. Alumina intermediate layer on porous stainless steel tube support was used to reduce effective support pore size and to provide a more uniform surface roughness. Novolac phenolic resin solution was then coated on the inside of porous stainless steel tube by slip casting while their viscosities were controlled from 5 centipoises to 30 centipoises. Carbonization was carried out at 700 °C in which thermal stress was minimized and high quality carbon films were prepared. The highest separationmore » performance characteristics were obtained using 20 cP phenolic resin solutions. The fabricated CMSM showed good separation factor for He/N 2 462, CO 2/N 2 97, and O 2/N 2 15.4. As the viscosity of polymer precursor solution was reduced from 20 cP to 15 cP, gas permeance values almost doubled with somewhat lower separation factor He/N 2 156, CO 2/N 2 88, and O 2/N 2 7.7.« less
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NASA Technical Reports Server (NTRS)
Yee, Layton; Bailey, Harry E.; Woodward, Henry T.
1961-01-01
A new technique for measuring heat-transfer rates on free-flight models in a ballistic range is described in this report. The accuracy of the heat-transfer rates measured in this way is shown to be comparable with the accuracy obtained in shock-tube measurements. The specific results of the present experiments consist of measurements of the stagnation-point heat-transfer rates experienced by a spherical-nosed model during flight through air and through carbon dioxide at velocities up to 18,000 feet per second. For flight through air these measured heat-transfer rates agree well with both the theoretically predicted rates and the rates measured in shock tubes. the heat-transfer rates agree well with the rates measured in a shock tube. Two methods of estimating the stagnation-point heat-transfer rates in carbon dioxide are compared with the experimental measurements. At each velocity the measured stagnation-point heat-transfer rate in carbon dioxide is about the same as the measured heat-transfer rate in air.
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A digital miniature x-ray tube with a high-density triode carbon nanotube field emitter
DOE Office of Scientific and Technical Information (OSTI.GOV)
Jeong, Jin-Woo; Kang, Jun-Tae; Choi, Sungyoul
2013-01-14
We have fabricated a digital miniature x-ray tube (6 mm in diameter and 32 mm in length) with a high-density triode carbon nanotube (CNT) field emitter for special x-ray applications. The triode CNT emitter was densely formed within a diameter of below 4 mm with the focusing-functional gate. The brazing process enables us to obtain and maintain a desired vacuum level for the reliable electron emission from the CNT emitters after the vacuum packaging. The miniature x-ray tube exhibited a stable and reliable operation over 250 h in a pulse mode at an anode voltage of above 25 kV.
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Properties of TiNi intermetallic compound industrially produced by combustion synthesis
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kaieda, Yoshinari
Most TiNi shape memory intermetallic compounds are conventionally produced by the process including high frequency induction vacuum melting and casting. A gravity segregation occurs in a cast TiNi ingot because of the big difference in the specific gravity between Ti and Ni. It is difficult to control accurately the phase transformation temperature of TiNi shape memory intermetallic compound produced by the conventional process, because the martensitic transformation temperature shifts by 10K due to the change in 0.1 % of Ni content. Homogeneous TiNi intermetallic compound is produced by the industrial process including combustion synthesis method, which is a newly developedmore » manufacturing process. In the new process, phase transformation temperatures of TiNi can be controlled accurately by controlling the ratio of Ti and Ni elemental starting powders. The chemical component, the impurities and the phase transformation temperatures of the TiNi products industrially produced by the process are revealed. These properties are vitally important when combustion synthesis method is applied to an industrial mass production process for producing TiNi shape memory intermetallic compounds. TiNi shape memory products are industrially and commercially produced today the industrial process including combustion synthesis. The total production weight in a year is 30 tins in 1994.« less
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ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES
Man-made carbonaceous nano-particles such as single and multi-walled carbon nano-tubes (CNT) and ultra-fine carbon black (UFCB) particles are finding increasing applications in industry, but their potential toxic effects is of concern. In aqueous media, these particles cluster in...
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NASA Astrophysics Data System (ADS)
Moradian, Rostam; Behzad, Somayeh; Azadi, Sam
2008-09-01
By using ab initio density functional theory we investigated the structural and electronic properties of semiconducting (7, 0), (8, 0) and (10, 0) carbon nanotube bundles. The energetic and electronic evolutions of nanotubes in the bundling process are also studied. The effects of inter-tube coupling on the electronic dispersions of semiconducting carbon nanotube bundles are demonstrated. Our results show that the inter-tube coupling decreases the energy gap in semiconducting nanotubes. We found that bundles of (7, 0) and (8, 0) carbon nanotubes have metallic feature, while (10, 0) bundle is a semiconductor with an energy gap of 0.22 eV. To clarify our results the band structures of isolated and bundled nanotubes are compared.
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Zhang, Jin; Cheng, Yi; Lu, Shanfu; Jia, Lichao; Shen, Pei Kang; Jiang, San Ping
2014-11-18
The inner tubes of carbon nanotubes (CNTs) have a significant promotion effect on the electrocatalytic activity of Pd nanoparticles (NPs) for the ethanol oxidation of direct alcohol fuel cells (DAFCs) and Pd NPs supported on CNTs with 3-7 walls show a much higher activity as compared to that supported on typical single-walled and multi-walled CNTs.
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Morphological transformations of BNCO nanomaterials: Role of intermediates
NASA Astrophysics Data System (ADS)
Wang, B. B.; Qu, X. L.; Zhu, M. K.; Levchenko, I.; Baranov, O.; Zhong, X. X.; Xu, S.; Ostrikov, K.
2018-06-01
Highly controllable structural transformation of various doped carbon and boron nitride nanomaterials have been achieved with the perspective of their application in microelectronics, optoelectronics, energy devices and catalytic reactions. Specifically, the syntheses of one-dimensional (1D) boron and nitrogen co-doped tube-like carbon nanorods and 2D vertical carbon and oxygen co-doped boron nitride nanosheets on silicon coated with gold films in N2-H2 plasma was demonstrated. During the synthesis of nanomaterials, boron carbide was used as carbon and boron sources. The results of characterizations by scanning and transmission electron microscopes, as well as micro-Raman and X-ray photoelectron spectroscopes indicate that the formation of different nanomaterials relates to the growth temperature and quantity of boron carbide. Specifically, 1D tube-like carbon nanorods doped with boron and nitrogen are formed at ∼910 °C using a small quantity of boron carbide, while 2D vertical boron nitride nanosheets doped with carbon and oxygen are grown at ∼870 °C using a large quantity of boron carbide. These studies indicate that the behaviors of a reactive intermediate product B2O3 on surfaces of Au nanoparticles play an important role in the formation of different nanomaterials, i.e., whether the B2O3 molecules deposited on Au nanoparticles are desorbed mainly determines the formation of different nanomaterials. The formation of 2D vertical carbon and oxygen co-doped boron nitride nanosheets is related to the high growth rate of edges of nanosheets. Furthermore, the photoluminescence (PL) properties of 1D boron and nitrogen co-doped tube-like carbon nanorods and 2D vertical carbon and oxygen co-doped boron nitride nanosheets were studied at room temperature. The PL results show that all the nanomaterials generate the ultraviolet, blue, green and red PL bands, but the 2D vertical carbon and oxygen co-doped boron nitride nanosheets emit more and stronger PL bands than the 1D boron and nitrogen co-doped tube-like carbon nanorods. The significant differences in the PL properties can be attributed to different carbon structures in these nanomaterials. These achievements can be used to synthesize and control the structures of nanomaterials and contribute to the development of the next generation optoelectronic nanodevices based on 1D and 2D nanomaterials.
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Method for extruding pitch based foam
Klett, James W.
2002-01-01
A method and apparatus for extruding pitch based foam is disclosed. The method includes the steps of: forming a viscous pitch foam; passing the precursor through an extrusion tube; and subjecting the precursor in said extrusion tube to a temperature gradient which varies along the length of the extrusion tube to form an extruded carbon foam. The apparatus includes an extrusion tube having a passageway communicatively connected to a chamber in which a viscous pitch foam formed in the chamber paring through the extrusion tube, and a heating mechanism in thermal communication with the tube for heating the viscous pitch foam along the length of the tube in accordance with a predetermined temperature gradient.
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Chan, Vera Bin San; Vinn, Olev; Li, Chaoyi; Lu, Xingwen; Kudryavtsev, Anatoliy B; Schopf, J William; Shih, Kaimin; Zhang, Tong; Thiyagarajan, Vengatesen
2015-03-01
The serpulid tubeworm, Hydroides elegans, is an ecologically and economically important species whose biology has been fairly well studied, especially in the context of larval development and settlement on man-made objects (biofouling). Nevertheless, ontogenetic changes associated with calcareous tube composition and structures have not yet been studied. Here, the ultrastructure and composition of the calcareous tubes built by H. elegans was examined in the three early calcifying juvenile stages and in the adult using XRD, FTIR, ICP-OES, SEM and Raman spectroscopy. Ontogenetic shifts in carbonate mineralogy were observed, for example, juvenile tubes contained more amorphous calcium carbonate and were predominantly aragonitic whereas adult tubes were bimineralic with considerably more calcite. The mineral composition gradually shifted during the tube development as shown by a decrease in Sr/Ca and an increase of Mg/Ca ratios with the tubeworm's age. The inner tube layer contained calcite, whereas the outer layer contained aragonite. Similarly, the tube complexity in terms of ultrastructure was associated with development. The sequential appearance of unoriented ultrastructures followed by oriented ultrastructures may reflect the evolutionary history of serpulid tube biominerals. As aragonitic structures are more susceptible to dissolution under ocean acidification (OA) conditions but are more difficult to be removed by anti-fouling treatments, the early developmental stages of the tubeworms may be vulnerable to OA but act as the important target for biofouling control. Copyright © 2015 Elsevier Inc. All rights reserved.
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An innovative molybdenum column liner for oxygen and hydrogen stable isotope analysis by pyrolysis.
Stuart-Williams, Hilary; Wong, S Chin; Farquhar, Graham D; Keitel, Claudia; Clayton, Stephen
2008-04-01
The most widely used method for pyrolysing samples for hydrogen or oxygen isotopic analysis involves heating them to greater than 1300 degrees C in a helium stream passed through a glassy carbon tube in an alumina casing. There are a number of difficulties with this. Glassy carbon tubes are expensive and interaction between the carbon tube and the outer casing produces unwanted carbon monoxide by reduction of the alumina at high temperatures. The latter effect is overwhelming if temperatures of 1400 degrees C or greater are used for pyrolysis. We experimented with lining alumina casings with pure molybdenum sheet. It is relatively cheap, conforms well to the interior of the reactor tube (to avoid carrier and sample bypassing of the carbon pack), resists high temperatures and neither oxidises excessively nor absorbs the gases. The main disadvantages are that silver sample cups must be used and that the molybdenum degrades over time by formation of the carbide. We can maintain sharp peaks, high precision and good accuracy over more than 700 solid samples for both hydrogen and oxygen. The reactors last longer for water injections. The molybdenum in the columns does not contribute greatly to memory effects. The precision of analysis is dependent on other factors as well as the pyrolysis column, but for oxygen we typically achieve approximately <0.2 per thousand (sucrose), <0.25 per thousand (water) and <0.25 per thousand (leaf), sometimes using only a linear correction of drift, after dividing the run into 1 to 3 segments.
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Guan, Yongxin; Feng, Yangyang; Mu, Yanping; Fang, Ling; Zhang, Huijuan; Wang, Yu
2016-11-25
Known as an excellent energy storage material, ZnMn 2 O 4 has a wide range of applications in supercapacitors. In this report, a special sandwich-like structure of ZnMn 2 O 4 /C has been first designed and synthesized via a simple hydrothermal method and subsequent calcinations. The designed special sandwich-like structure can benefit ion exchange and remit the probable volume changes during a mass of electrochemical reactions. Furthermore, the porous carbon nanosheets, derived from low-cost glucose, can effectively increase ion flux. Therefore, the novel sandwich-like ZnMn 2 O 4 nanoparticles encapsulated in carbon nanosheets can undoubtedly demonstrate an exceptional electrochemical performance for SCs. In this work, the composite material with porous sandwich-like structure exhibits excellent cyclic stability for 5000 cycles (∼5% loss) and high specific capacitance of 1786 F g -1 .
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NASA Astrophysics Data System (ADS)
Guan, Yongxin; Feng, Yangyang; Mu, Yanping; Fang, Ling; Zhang, Huijuan; Wang, Yu
2016-11-01
Known as an excellent energy storage material, ZnMn2O4 has a wide range of applications in supercapacitors. In this report, a special sandwich-like structure of ZnMn2O4/C has been first designed and synthesized via a simple hydrothermal method and subsequent calcinations. The designed special sandwich-like structure can benefit ion exchange and remit the probable volume changes during a mass of electrochemical reactions. Furthermore, the porous carbon nanosheets, derived from low-cost glucose, can effectively increase ion flux. Therefore, the novel sandwich-like ZnMn2O4 nanoparticles encapsulated in carbon nanosheets can undoubtedly demonstrate an exceptional electrochemical performance for SCs. In this work, the composite material with porous sandwich-like structure exhibits excellent cyclic stability for 5000 cycles (˜5% loss) and high specific capacitance of 1786 F g-1.
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Corrosion of Stainless-Steel Tubing in a Spacecraft Launch Environment
NASA Technical Reports Server (NTRS)
Barile, Ronald G.; MacDowell, Louis G.; Curran, Joe; Calle, Luz Maria; Hodge, Timothy
2001-01-01
This is a report of exposure of various metal tubing to oceanfront launch environments. The objective is to examine various types of corrosion-resistant tubing for Space Shuttle launch sites. The metals were stainless steels (austenitic, low-carbon, Mo-alloy, superaustenitic, duplex, and superferritic), Ni-Cr-Mo alloy, Ni-Mo-Cr-Fe-W alloy, and austenitic Ni-base superalloy.
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NASA Astrophysics Data System (ADS)
Tian, Qinghua; Tian, Yang; Zhang, Zhengxi; Yang, Li; Hirano, Shin-ichi
2015-09-01
Tin dioxide/carbon composites is an important class of promising candidates for anode materials with superior electrochemical performance and thus have attracted extensive attention. Herein, a tube-in-tube nanostructure, denoted as CNT@void@SnO2@C, has been fabricated by a facile and novel strategy. The possible formation mechanism is also discussed and determined by TEM, XRD and XPS characterizations. As a promising anode material for lithium-ion batteries, the CNT@void@SnO2@C exhibits superior lithium storage properties, delivering a reversible capacity of 702.5 mAh g-1 at 200 mA g-1 even after 350 cycles. The excellent performances should be benefited from the peculiar tube-in-tube nanostructure, in which SnO2 located between CNT and outermost carbon coating layers can sure the structural integrity and high conductivity during long-term cycling, and one-dimensional void space formed between the inner CNT and outer SnO2@C nanotubes, in particular, can provide larger free space for alleviating the huge volume variation of SnO2 and accommodating the stress formed during repeated discharge/charge process.
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Gonçalves, C; Ribeiro, J; Pereira, T; Luís, A L; Mauricio, A C; Santos, J D; Lopes, M A
2016-08-01
Peripheral nerve regeneration is a serious clinical problem. Presently, there are several nerve tube-guides available in the market, however with some limitations. The goal of this work was the development of a biomaterial with high electrical conductivity to produce tube-guides for nerve regeneration after neurotmesis injuries whenrver an end-to-end suture without tension is not possible. A matrix of poly(vinyl alcohol) (PVA) was used loaded with the following electrical conductive materials: COOH-functionalized multiwall carbon nanotubes (MWCNTs), poly(pyrrole) (PPy), magnesium chloride (MgCl2 ), and silver nitrate (AgNO3 ). The tube-guide production was carried out by a freezing/thawing process (physical crosslinking) with a final annealing treatment. After producing the tube-guide for nerve regeneration, the physicochemical characterization was performed. The most interesting results were achieved by loading PVA with 0.05% of PPy or COOH- functionalized CNTs. These tubes combined the electrical conductivity of carbon nanotubes (CNTs) and PPy with the biocompatibility of PVA matrix, with potential clinical application for nerve regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1981-1987, 2016. © 2016 Wiley Periodicals, Inc.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Scott, D.B.; Glaves, C.L.,
1987-07-01
Three model boilers, manufactured to simulate full-size tube sheet crevices, were tested with various secondary side environments. The first was faulted with organics representative of the decomposition of humic acid. The second was faulted with sodium carbonate and sodium hydroxide, while the third was faulted with sodium sulfate and sodium hydroxide. Each model contained seven tubes, which included Alloy 600 in the mill-annealed (MA) and thermally-treated (TT) conditions and Alloy 690 in the thermally-treated condition. Two models contained Alloy 800 tubes in the mill-annealed condition and one had Alloy 800 in the mill-annealed/cold-worked/glass-bead-peened condition. Two different sizes of tubesheet crevicesmore » were used in all model boilers. In the organics-faulted boiler, tubes of Alloy 600MA, Alloy 690TT and Alloy 800MA experienced no significant intergranular attack (IGA); however, the Alloy 600TT had intergranular attack (IGA) three to four grains deep. The carbonate-caustic faulted boiler experienced throughwall stress corrosion cracking (SCC) in all tubes of Alloy 600 MA and Alloy 800 MA. Eddy current indications were present in Alloy 690TT, Alloy 600TT and Alloy 800 in the mill-annealed/cold worked/glass-bead-peened condition. Metallographic examination of tubes from the third model boiler, faulted with sodium sulfate and caustic, revealed IGA in the mill-annealed Alloy 600 tubes. The IGA was more extensive in an Alloy 600 tube annealed at 1700/sup 0/F than an Alloy 600 tube annealed at 1875/sup 0/F.« less
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Experimentation and Modeling of Jet A Thermal Stability in a Heated Tube
NASA Technical Reports Server (NTRS)
Khodabandeh, Julia W.
2005-01-01
High performance aircraft typically use hydrocarbon fuel to regeneratively cool the airframe and engine components. As the coolant temperatures increase, the fuel may react with dissolved oxygen forming deposits that limit the regenerative cooling system performance. This study investigates the deposition of Jet A using a thermal stability experiment and computational fluid dynamics (CFD) modeling. The experimental portion of this study is performed with a high Reynolds number thermal stability (HiRets) tester in which fuel passes though an electrically heated tube and the fuel outlet temperature is held constant. If the thermal stability temperature of the fuel is exceeded, deposits form and adhere to the inside of the tube creating an insulating layer between the tube and the fuel. The HiRets tester measures the tube outer wall temperatures near the fuel outlet to report the effect of deposition occurring inside the tube. Final deposits are also estimated with a carbon burn off analysis. The CFD model was developed and used to simulate the fluid dynamics, heat transfer, chemistry, and transport of the deposit precursors. The model is calibrated to the experiment temperature results and carbon burn-off deposition results. The model results show that the dominant factor in deposition is the heated wall temperature and that most of the deposits are formed in the laminar sublayer. The models predicted a 7.0E-6 kilograms per square meter-sec deposition rate, which compared well to the carbon burn-off analysis deposition rate of 1.0E-6 kilograms per square meter-sec.
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Microstructural Characteristics and Mechanical Properties of an Electron Beam-Welded Ti/Cu/Ni Joint
NASA Astrophysics Data System (ADS)
Zhang, Feng; Wang, Ting; Jiang, Siyuan; Zhang, Binggang; Feng, Jicai
2018-04-01
Electron beam welding experiments of TA15 titanium alloy to GH600 nickel superalloy with and without a copper sheet interlayer were carried out. Surface appearance, microstructure and phase constitution of the joint were examined by optical microscopy, scanning electron microscopy and x-ray diffraction analysis. Mechanical properties of Ti/Ni and Ti/Cu/Ni joint were evaluated based on tensile strength and microhardness tests. The results showed that cracking occurred in Ti/Ni electron beam weldment for the formation of brittle Ni-Ti intermetallics, while a crack-free electron beam-welded Ti/Ni joint can be obtained by using a copper sheet as filler metal. The addition of copper into the weld affected the welding metallurgical process of the electron beam-welded Ti/Ni joint significantly and was helpful for restraining the formation of Ti-Ni intermetallics in Ti/Ni joint. The microstructure of the weld was mainly characterized by a copper-based solid solution and Ti-Cu interfacial intermetallic compounds. Ti-Ni intermetallic compounds were almost entirely suppressed. The hardness of the weld zone was significantly lower than that of Ti/Ni joint, and the tensile strength of the joint can be up to 282 MPa.
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NASA Astrophysics Data System (ADS)
Skiles, M.
2016-12-01
Groups of tiny ice pieces fall from the sky in the cold times and cover the high places. Later, the tiny ice pieces become water that moves to the lower places, where people can use it for drinking and stuff. The time when the tiny ice pieces turn to water is controlled by the sun. New tiny ice pieces from the sky, which are very white and don't take up much sun, group up and grow tall. When they become dark from getting old and large, and from getting covered in tiny dark bits from the sky, they take up more sun and turn to water. The more tiny dark bits, the faster they become water. Using a flying thing over the high places we can see how much water will come from the cover of tiny ice pieces by using ground looking things to see how tall it is, and and when it will become water by using picture taking things to see how much sun is taken up. The low places are happy to know how much water is in the high places.
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Microstructural Characteristics and Mechanical Properties of an Electron Beam-Welded Ti/Cu/Ni Joint
NASA Astrophysics Data System (ADS)
Zhang, Feng; Wang, Ting; Jiang, Siyuan; Zhang, Binggang; Feng, Jicai
2018-05-01
Electron beam welding experiments of TA15 titanium alloy to GH600 nickel superalloy with and without a copper sheet interlayer were carried out. Surface appearance, microstructure and phase constitution of the joint were examined by optical microscopy, scanning electron microscopy and x-ray diffraction analysis. Mechanical properties of Ti/Ni and Ti/Cu/Ni joint were evaluated based on tensile strength and microhardness tests. The results showed that cracking occurred in Ti/Ni electron beam weldment for the formation of brittle Ni-Ti intermetallics, while a crack-free electron beam-welded Ti/Ni joint can be obtained by using a copper sheet as filler metal. The addition of copper into the weld affected the welding metallurgical process of the electron beam-welded Ti/Ni joint significantly and was helpful for restraining the formation of Ti-Ni intermetallics in Ti/Ni joint. The microstructure of the weld was mainly characterized by a copper-based solid solution and Ti-Cu interfacial intermetallic compounds. Ti-Ni intermetallic compounds were almost entirely suppressed. The hardness of the weld zone was significantly lower than that of Ti/Ni joint, and the tensile strength of the joint can be up to 282 MPa.
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Liu, Dong; Yuan, Peng; Tan, Daoyong; Liu, Hongmei; Wang, Tong; Fan, Mingde; Zhu, Jianxi; He, Hongping
2012-12-15
Hierarchically porous carbons were prepared using a facile preparation method in which diatomite was utilized as both template and catalyst. The porous structures of the carbon products and their formation mechanisms were investigated. The macroporosity and microporosity of the diatomite-templated carbons were derived from replication of diatom shell and structure-reconfiguration of the carbon film, respectively. The macroporosity of carbons was strongly dependent on the original morphology of the diatomite template. The macroporous structure composed of carbon plates connected by the pillar- and tube-like macropores resulted from the replication of the central and edge pores of the diatom shells with disk-shaped morphology, respectively. And another macroporous carbon tubes were also replicated from canoe-shaped diatom shells. The acidity of diatomite dramatically affected the porosity of the carbons, more acid sites of diatomite template resulted in higher surface area and pore volume of the carbon products. The diatomite-templated carbons exhibited higher adsorption capacity for methylene blue than the commercial activated carbon (CAC), although the specific surface area was much smaller than that of CAC, due to the hierarchical porosity of diatomite-templated carbons. And the carbons were readily reclaimed and regenerated. Copyright © 2012 Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Vachon, Pierre-Luc
Composite laminates have strong in-plane mechanical properties, but they are generally weaker through their thickness. This specificity makes the laminates prone to delamination, particularly under low-velocity impact loads. Consequently numerous research efforts have been dedicated to developing interlaminar reinforcing methods, such as transverse stitching. The present project proposes the use of the stitching technique combined with a special stitching thread made of superelastic TiNi alloy. This technology is intended to improve the delamination toughness in composite laminates loaded in bending. In the first part of this study a numerical model was developed for analyzing composite structures. The 3-D finite element model was built with the ANSYS commercial software using 20-node solid and 8-node shell elements. The progressive damage modeling technique was used, allowing the prediction of delamination propagation in a laminate submitted to various loading modes. The model was validated for a plate under quasi-static traction load, and it was then used to simulate three-point bending tests. Secondly, carbon/epoxy composite panels were fabricated, with each panel containing unstitched and stitched specimens. Two different materials were used for the stitching thread: superelastic TiNi wires and Kevlar threads as a reference. Some stitched specimens were cut in slices in order to make some observations of the internal stitch using an optical microscope. Standardized low-velocity impact tests and compression after impact tests were carried out on stitched and unstitched specimens (ASTM D7136 and D7137). The Kevlar reinforcements have shown great performance in reducing the delaminated zone after impact, as well as in improving the residual compression strength. The TiNi reinforcements provided encouraging results during the impact tests, though being less effective than the Kevlar threads. During the compression after impact tests, only a slight difference could be measured between the TiNi-stitched and the unstitched specimens. Then the bending performance of the specimens was quantified experimentally by calculating the energy required to create a unit volume of damaged material (Gv, J/mm3). This metric is similar to the Strain Energy Release Rate (SERR) commonly used in studies on delamination. According to the experimental results, the damage resistance in three-point bending was not improved by the Kevlar reinforcements, despite the reduced damaged zone after the impact test. Indeed, when the strain energy in bending is relativized to the induced damaged volume during propagation, it turns out that the TiNi reinforcements are more effective than the Kevlar's for improving the damage resistance. Finally, the numerical study on the behavior of both types of stitched reinforcements allowed identifying subtle differences between those. Indeed, both stitching threads (TiNi and Kevlar) promoted the interlaminar propagation of the delamination during simulation of the bending test, with this behavior being less pronounced for the TiNi-stitched plate. However the Kevlar threads seemed more effective for stopping this propagation in the zones between the stitches. Keywords: composite materials, stitching, numerical model, shape memory alloy, three-point bending, low-velocity impact, ultrasound imaging.
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TinyOS-based quality of service management in wireless sensor networks
Peterson, N.; Anusuya-Rangappa, L.; Shirazi, B.A.; Huang, R.; Song, W.-Z.; Miceli, M.; McBride, D.; Hurson, A.; LaHusen, R.
2009-01-01
Previously the cost and extremely limited capabilities of sensors prohibited Quality of Service (QoS) implementations in wireless sensor networks. With advances in technology, sensors are becoming significantly less expensive and the increases in computational and storage capabilities are opening the door for new, sophisticated algorithms to be implemented. Newer sensor network applications require higher data rates with more stringent priority requirements. We introduce a dynamic scheduling algorithm to improve bandwidth for high priority data in sensor networks, called Tiny-DWFQ. Our Tiny-Dynamic Weighted Fair Queuing scheduling algorithm allows for dynamic QoS for prioritized communications by continually adjusting the treatment of communication packages according to their priorities and the current level of network congestion. For performance evaluation, we tested Tiny-DWFQ, Tiny-WFQ (traditional WFQ algorithm implemented in TinyOS), and FIFO queues on an Imote2-based wireless sensor network and report their throughput and packet loss. Our results show that Tiny-DWFQ performs better in all test cases. ?? 2009 IEEE.
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Cold cathode vacuum discharge tube
Boettcher, G.E.
1998-04-14
A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.
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NASA Astrophysics Data System (ADS)
Luck, C. F.
1983-06-01
This report documents the efforts of Raytheon Company to conduct a manufacturing methods and technology (MM&T) program for 10.6 micrometer carbon dioxide TEA lasers. A set of laser parameters is given and a conforming tube design is described. Results of thermal and mechanical stress analyses are detailed along with a procedure for assembling and testing the laser tube. Also provided are purchase specifications for optics and process specifications for some of the essential operations.
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Jiang, Yuan; Liese, Eric; Zitney, Stephen E.; ...
2018-02-25
This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Jiang, Yuan; Liese, Eric; Zitney, Stephen E.
This paper presents a baseline design and optimization approach developed in Aspen Custom Modeler (ACM) for microtube shell-and-tube exchangers (MSTEs) used for high- and low-temperature recuperation in a 10 MWe indirect supercritical carbon dioxide (sCO 2) recompression closed Brayton cycle (RCBC). The MSTE-type recuperators are designed using one-dimensional models with thermal-hydraulic correlations appropriate for sCO 2 and properties models that capture considerable nonlinear changes in CO 2 properties near the critical and pseudo-critical points. Using the successive quadratic programming (SQP) algorithm in ACM, optimal recuperator designs are obtained for either custom or industry-standard microtubes considering constraints based on current advancedmore » manufacturing techniques. The three decision variables are the number of tubes, tube pitch-to-diameter ratio, and tube diameter. Five different objective functions based on different key design measures are considered: minimization of total heat transfer area, heat exchanger volume, metal weight, thermal residence time, and maximization of compactness. Sensitivities studies indicate the constraint on the maximum number of tubes per shell does affect the number of parallel heat exchanger trains but not the tube selection, total number of tubes, tube length and other key design measures in the final optimal design when considering industry-standard tubes. In this study, the optimally designed high- and low-temperature recuperators have 47,000 3/32 inch tubes and 63,000 1/16 inch tubes, respectively. In addition, sensitivities to the design temperature approach and maximum allowable pressure drop are studied, since these specifications significantly impact the optimal design of the recuperators as well as the thermal efficiency and the economic performance of the entire sCO 2 Brayton cycle.« less
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Revealing small-scale diffracting discontinuities by an optimization inversion algorithm
NASA Astrophysics Data System (ADS)
Yu, Caixia; Zhao, Jingtao; Wang, Yanfei
2017-02-01
Small-scale diffracting geologic discontinuities play a significant role in studying carbonate reservoirs. The seismic responses of them are coded in diffracted/scattered waves. However, compared with reflections, the energy of these valuable diffractions is generally one or even two orders of magnitude weaker. This means that the information of diffractions is strongly masked by reflections in the seismic images. Detecting the small-scale cavities and tiny faults from the deep carbonate reservoirs, mainly over 6 km, poses an even bigger challenge to seismic diffractions, as the signals of seismic surveyed data are weak and have a low signal-to-noise ratio (SNR). After analyzing the mechanism of the Kirchhoff migration method, the residual of prestack diffractions located in the neighborhood of the first Fresnel aperture is found to remain in the image space. Therefore, a strategy for extracting diffractions in the image space is proposed and a regularized L 2-norm model with a smooth constraint to the local slopes is suggested for predicting reflections. According to the focusing conditions of residual diffractions in the image space, two approaches are provided for extracting diffractions. Diffraction extraction can be directly accomplished by subtracting the predicted reflections from seismic imaging data if the residual diffractions are focused. Otherwise, a diffraction velocity analysis will be performed for refocusing residual diffractions. Two synthetic examples and one field application demonstrate the feasibility and efficiency of the two proposed methods in detecting the small-scale geologic scatterers, tiny faults and cavities.
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Xu, Ben; Yang, Yi; Jia, Zhenbao; Wang, D N
2017-06-26
A compact and high sensitivity sensor with a fiber-tip structure is proposed and demonstrated for simultaneously liquid refractive index (RI) and temperature sensing. The device is fabricated by inserting a tiny segment of capillary tube between single-mode fibers (SMFs) to form two cascaded Fabry-Perot interferometers (FPIs). The theoretical and experimental results demonstrate that the ambient liquid RI and temperature can be simultaneously determined by the intensity and shift of the resonant wavelength in the reflection spectrum. Our proposed device has the highest RI sensitivity of ~216.37 dB/RIU at the RI value of 1.30; a high spatial resolution owing to its compact size (with dimension <400 μm) makes it promising for high precision bio/chemical sensing applications.
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Farajzadeh, Mir Ali; Bamorowat, Mahdi; Mogaddam, Mohammad Reza Afshar
2016-11-01
An efficient, reliable, sensitive, rapid, and green analytical method for the extraction and determination of neonicotinoid insecticides in aqueous samples has been developed using ionic liquid phase microextraction coupled with high performance liquid chromatography-diode array detector. In this method, a few microliters of 1-hexyl-3-methylimidazolium hexafluorophosphate (as an extractant) is added onto a ringer tablet and it is transferred into a conical test tube containing aqueous phase of the analytes. By manually shaking, the ringer tablet is dissolved and the extractant is released into the aqueous phase as very tiny droplets to provide a cloudy solution. After centrifuging the extracted analytes into ionic liquid are collected at the bottom of a conical test tube. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.12 and 0.33 and 0.41 and 1.11ngmL(-1), respectively. Extraction recoveries and enrichment factors were from 66% to 84% and 655% to 843%, respectively. Finally different aqueous samples were successfully analyzed using the proposed method. Copyright © 2016 Elsevier B.V. All rights reserved.
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Carbon nanotube vacuum gauges utilizing long, dissipative tubes
NASA Astrophysics Data System (ADS)
Kaul, Anupama B.; Manohara, Harish M.
2008-04-01
A carbon nanotube-based thermal conductivity vacuum gauge is described which utilizes 5-10 μm long diffusively contacted SWNTs for vacuum sensing. By etching the thermal SiO II beneath the tubes and minimizing heat conduction through the substrate, pressure sensitivity was extended toward higher vacuums. The pressure response of unannealed and annealed devices was compared to that of released devices. The released devices showed sensitivity to pressure as low as 1 x 10 -6 Torr. The sensitivity increased more dramatically with power for the released device compared to that of the unreleased device. Low temperature electronic transport measurements of the tubes were suggestive of a thermally activated hopping mechanism where the activation energy for hopping was calculated to be ~ 39 meV.
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NASA Astrophysics Data System (ADS)
de Blauwe, K.; Mowbray, D. J.; Miyata, Y.; Ayala, P.; Shiozawa, H.; Rubio, A.; Hoffmann, P.; Kataura, H.; Pichler, T.
2010-09-01
Narrow diameter tubes and especially (6,5) tubes with a diameter of 0.75 nm are currently one of the most studied carbon nanotubes because their unique optical and especially luminescence response makes them exceptionally suited for biomedical applications. Here we report on a detailed analysis of the electronic structure of nanotubes with (6,5) and (6,4) chiralities using a combined experimental and theoretical approach. From high-energy spectroscopy involving x-ray absorption and photoemission spectroscopy the detailed valence- and conduction-band response of these narrow diameter tubes is studied. The observed electronic structure is in sound agreement with state of the art ab initio calculations using density-functional theory.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Cobb, G.P.; Braman, R.S.; Gilbert, R.A.
Atmospheric organics were sampled and analyzed by using the carbon hollow tube-gas chromatography method. Chromatograms from spice mixtures, cigarettes, and ambient air were analyzed. Principal factor analysis of row order chromatographic data produces factors which are eigenchromatograms of the components in the samples. Component sources are identified from the eigenchromatograms in all experiments and the individual eigenchromatogram corresponding to a particular source is determined in most cases. Organic sources in ambient air and in cigaretts are identified with 87% certainty. Analysis of clove cigarettes allows the determination of the relative amount of clove in different cigarettes. A new nondestructive qualitymore » control method using the hollow tube-gas chromatography analysis is discussed.« less
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Carbon dioxide laser microsurgery of the uterine tube.
Baggish, M S; Chong, A P
1981-07-01
The carbon dioxide (CO2) laser was used to perform microsurgical excision of obstructed tubal segments in rabbit and human subjects. Approximation of the freshly severed tubes by means of laser "welding" was evaluated in both groups investigated. More important, the laser beam cuts accurately and atraumatically while sealing small vascular channels. Scanning electron microscopic studies of the human fallopian tube following laser surgery were done to determine the extent of tissue injury. At a distance of 1 mm distal to the vaporization and necrotic impact zone, normal tubal anatomy was observed. Follow-up data are presented for 7 women who underwent laser beam tuboplasty between 1979 and 1980. The principle advantages of the CO2 laser are its precise control, minimal tissue injury, and hemostatic properties.
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Failure Analysis of a Service Tube
NASA Astrophysics Data System (ADS)
Xie, Zhongdong; Cai, Weiguo; Li, Zhenxing; Guan, YiMing; Zhang, Baocheng; Yang, XiaoTong
2017-12-01
One tube was cracked used in the primary reformer furnace in a fertilizer plant for two and half years. In order to find out the causes of cracking, the methods for chemical composition analysis, macro- and microstructure analysis, penetrant testing, weld analysis, crack and surface damage analysis, mechanics property analysis, high temperature endurance performance analysis, stress and wall thickness calculation were adopted. The integrated assessment results showed that the carbon content of the tube was in the lower limit of the standard range; the tube effective wall thickness was too small; local overheating leads to tube cracking in use process.
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Cool Space Bags Filled With Funny Voice Air Studying Space Rain
NASA Astrophysics Data System (ADS)
Halford, A. J.; MacDonald, E.
2016-12-01
Today I will tell you a bit about our work: big bags of funny voice air looking at space rain into the top of the sky, where there's not much sky left. So what makes stuff, both hot and cold tiny stuff, and I mean tiny tiny things, like really tiny things, fall into the top of the sky? Many different things. Some of these things are really really long waves, long waves, short waves that make angry cat noises, and short waves that sound like animals that fly in the morning along with other things. But how do we study this? We use big bags filled with funny voice air to fly near the top of the sky. When the tiny things that can't be seen rain into the top of the sky they make lights that can not be seen by eye, some move fast like the tiny things and many move slower. Our big bags of funny voice air carry computers and things that can see this light that can not be seen by eye. We use this not seen light to tell us what stuff fell into the top of the sky. Some waves will push the slower tiny stuff and some waves will push the faster tiny stuff. By looking at the number of slow and fast stuff we can help find out what pushed it. With our friends, computers who fly in space, we can see the different waves in space and see if it was where the tiny things rained into the top of the sky. Why do we study this? These tiny things can hurt our friends in space, both the computers as well as people in space and here in the world. We want to be able to know when this space rain will happen. But in order to know when these tiny tiny things will fall into the sky we have to first learn how to best look at and study them. Then we will know how often they rain down, where this space rain happens, and how large of an area this space rain falls in.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-01-17
..., Taiwan, Thailand, and Turkey; Scheduling of Full Five-Year Reviews AGENCY: United States International... Turkey, the antidumping duty orders on welded carbon steel pipe and tube from India, Thailand, and Turkey...
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Carbon Nanotubes on Titanium Substrates for Stray Light Suppression
NASA Technical Reports Server (NTRS)
Hagopian, John; Getty, Stephanie; Quijada, Manuel
2011-01-01
A method has been developed for growing carbon nanotubes on a titanium substrate, which makes the nano tubes ten times blacker than the current state-of-the-art paints in the visible to near infrared. This will allow for significant improvement of stray light performance in scientific instruments, or any other optical system. Because baffles, stops, and tubes used in scientific observations often undergo loads such as vibration, it is critical to develop this surface treatment on structural materials. This innovation optimizes the carbon nano - tube growth for titanium, which is a strong, lightweight structural material suitable for spaceflight use. The steps required to grow the nanotubes require the preparation of the surface by lapping, and the deposition of an iron catalyst over an alumina stiction layer by e-beam evaporation. In operation, the stray light controls are fabricated, and nanotubes (multi-walled 100 microns in length) are grown on the surface. They are then installed in the instruments or other optical devices.
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Advanced carbon nanotubes functionalization
NASA Astrophysics Data System (ADS)
Setaro, A.
2017-10-01
Similar to graphene, carbon nanotubes are materials made of pure carbon in its sp2 form. Their extended conjugated π-network provides them with remarkable quantum optoelectronic properties. Frustratingly, it also brings drawbacks. The π-π stacking interaction makes as-produced tubes bundle together, blurring all their quantum properties. Functionalization aims at modifying and protecting the tubes while hindering π-π stacking. Several functionalization strategies have been developed to circumvent this limitation in order for nanotubes applications to thrive. In this review, we summarize the different approaches established so far, emphasizing the balance between functionalization efficacy and the preservation of the tubes’ properties. Much attention will be given to a functionalization strategy overcoming the covalent-noncovalent dichotomy and to the implementation of two advanced functionalization schemes: (a) conjugation with molecular switches, to yield hybrid nanosystems with chemo-physical properties that can be tuned in a controlled and reversible way, and; (b) plasmonic nanosystems, whose ability to concentrate and enhance the electromagnetic fields can be taken advantage of to enhance the optical response of the tubes.
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Flame Retardant Effect of Nano Fillers on Polydimethylsiloxane Composites.
Jagdale, Pravin; Salimpour, Samera; Islam, Md Hujjatul; Cuttica, Fabio; Hernandez, Francisco C Robles; Tagliaferro, Alberto; Frache, Alberto
2018-02-01
Polydimethylsiloxane has exceptional fire retardancy characteristics, which make it a popular polymer in flame retardancy applications. Flame retardancy of polydimethylsiloxane with different nano fillers was studied. Polydimethylsiloxane composite fire property varies because of the shape, size, density, and chemical nature of nano fillers. In house made carbon and bismuth oxide nano fillers were used in polydimethylsiloxane composite. Carbon from biochar (carbonised bamboo) and a carbon by-product (carbon soot) were selected. For comparative study of nano fillers, standard commercial multiwall carbon nano tubes (functionalised, graphitised and pristine) as nano fillers were selected. Nano fillers in polydimethylsiloxane positively affects their fire retardant properties such as total smoke release, peak heat release rate, and time to ignition. Charring and surface ceramization are the main reasons for such improvement. Nano fillers in polydimethylsiloxane may affect the thermal mobility of polymer chains, which can directly affect the time to ignition. The study concludes that the addition of pristine multiwall carbon nano tubes and bismuth oxide nano particles as filler in polydimethylsiloxane composite improves the fire retardant property.
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Gallium-mediated growth of multiwall carbon nanotubes
NASA Astrophysics Data System (ADS)
Pan, Zheng Wei; Dai, Sheng; Beach, David B.; Evans, Neal D.; Lowndes, Douglas H.
2003-03-01
Liquid gallium was used as a viable and effective solvent and template for high-yield growth of multiwall carbon nanotubes. The gallium-mediated nanotubes thus obtained differ morphologically from nanotubes obtained by using transition metals as catalysts. The nanotubes have a pin-like morphology, generally composed of an oval-shaped tip filled with liquid gallium and a tapered hollow body. The inner diameter of the tube is so large that the inner/outer diameter ratio is usually larger than 0.9. The tubes are naturally opened at both ends. These gallium-filled nanotubes may be used as a nanothermometer in the temperature range of 30 to 550 °C. This study opens an interesting route for carbon nanotube synthesis.
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Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength
NASA Technical Reports Server (NTRS)
Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.
2013-01-01
Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.
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Spectroscopic properties and STM images of carbon nanotubes
NASA Astrophysics Data System (ADS)
Rubio, A.
We present a theoretical study of the role of the local environment in the electronic properties of carbon nanotubes: isolated single- and multi-wall nanotubes, nanotube ropes, tubes supported on gold and cut to finite length. Interaction with the substrate or with other tubes does not alter the scanning tunneling microscopy patterns (STM) observed for isolated tubes. A finite-length nanotube shows standing-wave patterns that can be completely characterized by a set of four different three-dimensional shapes. These patterns are understood in terms of a simple π-electron tight-binding (TB) model. STM-topographic images of topological defects ani (pentagon/heptagon pair) and tube caps have also been studied. In both cases the image obtained depends on the sign of the applied voltage and can be described in terms of the previous catalog of STM images (interference between electronic waves scattered by the defect). We have also computed the electronic density of states for isolated tubes with different chiralities and radii, confirming a correlation between the peak structure in the DOS and nanotube diameter. However, the metallic plateau in the DOS also depends on the nanotube chirality. Furthermore the conduction an valence band structures are not fully symmetrical to one another. This anisotropy shows up in the DOS and indicates the limitations of the π-TB model in describing spectroscopic data. In contrast to STM images, here the interaction with the substrate does modify the energy levels of the nanotube. We observe opening of small pseudogaps around the Fermi level and broadening of the sharp van Hove singularities of the isolated single-walled nanotubes that can be used to extract useful information about the tube structure and bonding. The combination of STM and spectroscopic studies provides a new way to address the electronic and structural properties of carbon and composite nanotubes.
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Zhuo, Hao; Hu, Yijie; Tong, Xing; Chen, Zehong; Zhong, Linxin; Lai, Haihong; Liu, Linxiang; Jing, Shuangshuang; Liu, Qingzhong; Liu, Chuanfu; Peng, Xinwen; Sun, Runcang
2018-05-01
Ultralight and compressible carbon materials have promising applications in strain and pressure detection. However, it is still difficult to prepare carbon materials with supercompressibility, elasticity, stable strain-electrical signal response, and ultrasensitive detection limits, due to the challenge in structural regulation. Herein, a new strategy to prepare a reduced graphene oxide (rGO)-based lamellar carbon aerogels with unexpected and integrated performances by designing wave-shape rGO layers and enhancing the interaction among the rGO layers is demonstrated. Addition of cellulose nanocrystalline and low-molecular-weight carbon precursors enhances the interaction among rGO layers and thus produces an ultralight, flexible, and superstable structure. The as-prepared carbon aerogel displays a supercompressibility (undergoing an extreme strain of 99%) and elasticity (100% height retention after 10 000 cycles at a strain of 30%), as well as stable strain-current response (at least 10 000 cycles). Particularly, the carbon aerogel is ultrasensitive for detecting tiny change in strain (0.012%) and pressure (0.25 Pa), which are the lowest detection limits for compressible carbon materials reported in the literature. Moreover, the carbon aerogel exhibits excellent bendable performance and can detect an ultralow bending angle of 0.052°. Additionally, the carbon aerogel also demonstrates its promising application as wearable devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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NASA Technical Reports Server (NTRS)
1994-01-01
Petroleum Remediation Product (PRP) is a new way of cleaning up oil spills. It consists of thousands of microcapsules, tiny balls of beeswax with hollow centers, containing live microorganisms and nutrients to sustain them. As oil flows through the microcapsule's shell, it is consumed and digested by the microorganisms. Pressure buildup causes the PRP to explode and the enzymes, carbon dioxide and water are released into the BioBoom used in conjunction with PRP, preventing contaminated water from spreading. The system incorporates technology originally developed at the Jet Propulsion Laboratory and Marshall Space Flight Center.
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Coated woven materials and method of preparation
McCreary, William J.; Carroll, David W.
1981-01-01
Coating of woven materials so that not only the outer surfaces are coated has been a problem. Now, a solution to that problem is the following: Woven materials are coated with materials, for example with metals or with pyrolytic carbon, which materials are deposited in Chemical Vapor Deposition (CVD) reactions using a fluidized bed so that the porosity of the woven material is retained and so that the tiny filaments which make up the strands which are woven (including inner as well as outer filaments) are substantially uniformly coated.
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Corrosion behavior of heat-treated intermetallic titanium-nickel in hydrochloric acid solutions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Starosvetsky, D.; Khaselev, O.; Yahalom, J.
1998-07-01
Samples of 45% Ti-55% Ni alloy (Ti-Ni) were heat-treated in air at 450 C, and their anodic behavior in 0.3 M, 1 M, 2 M, and 4 M hydrochloric acid (HCl) solutions was studied. In 0.3 M HCl, heat-treated Ti-Ni was passive, and very low anodic currents were observed. In 1 M and 2 M HCl, heat-treated Ti-Ni was dissolved actively, while heat-treated and surface-ground Ti-Ni became passive. The effect was explained by selective oxidation of Ti-Ni and formation of a layered structure on its surface with discontinuous titanium oxide and a nickel-enriched zone underneath. The latter was dissolved inmore » the HCl solutions, thus accelerating failure of the Ti-Ni samples. In 4 M HCl, heat-treated and heat-treated/ground samples were dissolved readily.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Hou, Huilong; Simsek, Emrah; Stasak, Drew
The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. In this paper, we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g -1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as -7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress–strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti 2Ni precipitates typically onemore » micron in size with a large aspect ratio enclosing the TiNi matrix. Finally, a stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti 2Ni precipitates is believed to be the origin of the unique superelasticity behavior.« less
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Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat
NASA Astrophysics Data System (ADS)
Hou, Huilong; Simsek, Emrah; Stasak, Drew; Hasan, Naila Al; Qian, Suxin; Ott, Ryan; Cui, Jun; Takeuchi, Ichiro
2017-10-01
The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. Here we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g-1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as -7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress-strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti2Ni precipitates typically one micron in size with a large aspect ratio enclosing the TiNi matrix. A stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti2Ni precipitates is believed to be the origin of the unique superelasticity behavior.
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Cathode readout with stripped resistive drift tubes
NASA Astrophysics Data System (ADS)
Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.
1995-12-01
A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.
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Dislocation Onset and Glide in Carbon Nanotubes under Torsion
NASA Astrophysics Data System (ADS)
Dumitrica, Traian; Zhang, Dong-Bo; James, Richard
2009-03-01
The torsional plastic response of carbon nanotubes is comprehensively described in the objective molecular dynamics framework [1-3]. It is shown that an (n,m) tube is prone to slip along a nearly-axial helical path, which introduces a distinct (+1,-1) change in the wrapping index. The low energy realization occurs without loss of mass, via nucleation of a 5-7-7-5 dislocation dipole, followed by a nearly-axial glide of the 5-7 dislocation. The onset of plasticity depends not only on chirality but also on handedness. For a given handedness of the applied twist, chiral tubes of opposed handedness are most susceptible to yield. A right-handed applied twist on an armchair (zig-zag) tube leads to a right- (left-) handed tube. [4pt] [1] T. Dumitrica and R.D. James, Objective Molecular Dynamics, Journal of the Mechanics and Physics of Solids 55, 2206 (2007). [0pt] [2] D.-B. Zhang, M. Hua, and T. Dumitrica, Stability of Polycrystalline and Wurtzite Si Nanowires via Symmetry-Adapted Tight-Binding Objective Molecular Dynamics, Journal of Chemical Physics 128, 084104 (2008). [0pt] [3] D.-B. Zhang and T. Dumitrica, Elasticity of Ideal Single-Walled Carbon Nanotubes via Symmetry-Adapted Tight-Binding Objective Modeling, Applied Physics Letters 93, 031919 (2008).
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Comparison of various solutions to dissolve critical care diet clots.
Parker, Valerie J; Freeman, Lisa M
2013-01-01
Enteral feeding tubes are frequently placed in animals to provide assisted nutritional support; however, one major reported complication is clogging of the tubes. The goal of this study was to determine which solution is most effective at dissolving in vitro clots made using a veterinary canned critical care diet. Various solutions were tested for their ability to dissolve enteral feed clots, including water, meat tenderizers in water, predetermined amounts of pancreatic enzymes (with and without sodium bicarbonate) in water, carbonated beverages, and cranberry juice. The solution that resulted in the greatest dissolution was ¼ teaspoon pancreatic enzymes and 325 mg sodium bicarbonate in 5 mL water, which was significantly better than all other solutions (water: P = 0.03; ¼ teaspoon pancreatic enzymes in water: P = 0.002; all others: P < 0.001). Water was significantly better than all carbonated beverages and cranberry juice (P < 0.001). The least successful solution was ½ teaspoon pancreatic enzymes and sodium bicarbonate in water. Despite anecdotal reports of using carbonated beverages, cranberry juice, and ½ teaspoon pancreatic enzymes to unclog feeding tubes, all were significantly less effective than water. In vivo studies to evaluate the effectiveness of methods to unclog feeding tubes are warranted to further investigate these findings. © Veterinary Emergency and Critical Care Society 2013.
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Chen, Xin; Hu, Rui; Bai, Fan
2017-01-01
The influences of diameter and length of the Fe−N4-patched carbon nanotubes (Fe−N4/CNTs) on oxygen reduction reaction (ORR) activity were investigated by density functional theory method using the BLYP/DZP basis set. The results indicate that the stability of the Fe−N4 catalytic site in Fe−N4/CNTs will be enhanced with a larger tube diameter, but reduced with shorter tube length. A tube with too small a diameter makes a Fe−N4 site unstable in acid medium since Fe−N and C−N bonds must be significantly bent at smaller diameters due to hoop strain. The adsorption energy of the ORR intermediates, especially of the OH group, becomes weaker with the increase of the tube diameter. The OH adsorption energy of Fe−N4/CNT with the largest tube diameter is close to that on Pt(111) surface, indicating that its catalytic property is similar to Pt. Electronic structure analysis shows that the OH adsorption energy is mainly controlled by the energy levels of Fe 3d orbital. The calculation results uncover that Fe−N4/CNTs with larger tube diameters and shorter lengths will exhibit better ORR activity and stability. PMID:28772903
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Apparatus for converting hydrocarbon fuel into hydrogen gas and carbon dioxide
Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.
2001-01-01
A hydrocarbon fuel reformer (200) is disclosed suitable for producing synthesis hydrogen gas from reactions with hydrocarbons fuels, oxygen, and steam. The reformer (200) comprises first and second tubes (208,218). The first tube (208) includes a first catalyst (214) and receives a first mixture of steam and a first fuel. The second tube (218) is annularly disposed about the first tube (208) and receives a second mixture of an oxygen-containing gas and a second fuel. In one embodiment, a third tube (224) is annularly disposed about the second tube (218) and receives a first reaction reformate from the first tube (208) and a second reaction reformate from the second tube (218). A catalyst reforming zone (260) annularly disposed about the third tube (224) may be provided to subject reformate constituents to a shift reaction. In another embodiment, a fractionator is provided to distill first and second fuels from a fuel supply source.
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Titania carbon nanotube composites for enhanced photocatalysis
NASA Astrophysics Data System (ADS)
Pyrgiotakis, Georgios
Photocatalytic composites have been used for the past few decades in a wide range of applications. The most common application is the purification of air and water by removing toxic compounds. There is limited use however towards biocidal applications. Despite their high efficiency, photocatalytic materials are not comparable to the effectiveness of conventional biocidal compounds such as chlorine and alcoholic disinfectants. On the other hand, nearly a decade ago with the discovery of the carbon nanotubes a new vibrant scientific field emerged. Nanotubes are unique structures of carbon that posse amazing electrical, mechanical and thermal properties. In this research carbon nanotubes are used as photocatalytic enhancers. They were coated with anatase titania to form a composite material. Two different types of nanotubes (metallic versus non-metallic) were used and the photocatalytic activity was measured. The metallic tubes demonstrated exceptional photocatalytic properties, while non-metallic tubes had low photocatalytic efficiency. The reason for that difference was investigated and was the major focus of this research. The research concluded that the reasons for the high efficiency of the carbon nanotubes were (i) the metallic nature of the tubes and (ii) the possible bond between the titania coating and the underlying graphite layers (C-O-Ti). Since both composites had the same indications regarding the C-O-Ti bond, the metallic nature of the carbon nanotubes is believed to be the most dominant factor contributing to the enhancement of the photocatalysis. The composite material may have other potential applications such as for sensing and photovoltaic uses.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-21
...'') U.S. affiliated importer FitMAX Inc. (``FitMAX'') on June 2, 2010 and June 16, 2010. FitMAX... carbon- quality light-walled steel pipe and tube, of rectangular (including square) cross section, having...
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NASA Astrophysics Data System (ADS)
Xu, Yi; Li, Liuhe; Luo, Sida; Lu, Qiuyuan; Gu, Jiabin; Lei, Ning; Huo, Chunqin
2017-01-01
Enhanced glow discharge plasma immersion ion implantation and deposition (EGD-PIII&D) have been proved to be highly effective for depositing diamond-like carbon (DLC) films on the inner surface of the slender quartz tube with a deposition rate of 1.3 μm/min. Such a high-efficiency DLC films deposition was explained previously as the short electrons mean free path to cause large collision frequency between electrons and neutral particles. However, in this paper, we found that the inner surface material of the tube itself play a vital role on the films deposition. To disclose the mechanism of this phenomenon, the effect of different inner surface materials on plasma discharge was experimentally and theoretically investigated. Then a self-enhancing plasma discharge is discovered. It is found that secondary electrons emitted from the inner surface material, whatever it is the tube inner surface or deposited DLC films, can dramatically enhance the plasma discharge to improve the DLC films deposition rate.
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NASA Astrophysics Data System (ADS)
Shulga, A. V.
2013-03-01
The ring tensile test method was optimized and successfully used to obtain precise data for specimens of the cladding tubes of AISI type 316 austenitic stainless steels and ferritic-martensitic stainless steel. The positive modifications in the tensile properties of the stainless steel cladding tubes fabricated by powder metallurgy and hot isostatic pressing of melt atomized powders (PM HIP) when compared with the cladding tubes produced by traditional technology were found. Presently, PM HIP is also used in the fabrication of oxide dispersion strengthened (ODS) ferritic-martensitic steels. The high degree of homogeneity of the distribution of carbon and boron as well the high dispersivity of the phase-structure elements in the specimens manufactured via PM HIP were determined by direct autoradiography methods. These results correlate well with the increase of the tensile properties of the specimens produced by PM HIP technology.
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Design of Boiler Welding for Improvement of Lifetime and Cost Control.
Thong-On, Atcharawadi; Boonruang, Chatdanai
2016-11-03
Fe-2.25Cr-1Mo a widely used material for headers and steam tubes of boilers. Welding of steam tube to header is required for production of boiler. Heat affected zone of the weld can have poor mechanical properties and poor corrosion behavior leading to weld failure. The cost of material used for steam tube and header of boiler should be controlled. This study propose a new materials design for boiler welding to improve the lifetime and cost control, using tungsten inert gas (TIG) welding of Fe-2.25Cr-1Mo tube to carbon steel pipe with chromium-containing filler. The cost of production could be reduced by the use of low cost material such as carbon steel pipe for boiler header. The effect of chromium content on corrosion behavior of the weld was greater than that of the microstructure. The lifetime of the welded boiler can be increased by improvement of mechanical properties and corrosion behavior of the heat affected zone.
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Design of Boiler Welding for Improvement of Lifetime and Cost Control
Thong-On, Atcharawadi; Boonruang, Chatdanai
2016-01-01
Fe-2.25Cr-1Mo a widely used material for headers and steam tubes of boilers. Welding of steam tube to header is required for production of boiler. Heat affected zone of the weld can have poor mechanical properties and poor corrosion behavior leading to weld failure. The cost of material used for steam tube and header of boiler should be controlled. This study propose a new materials design for boiler welding to improve the lifetime and cost control, using tungsten inert gas (TIG) welding of Fe-2.25Cr-1Mo tube to carbon steel pipe with chromium-containing filler. The cost of production could be reduced by the use of low cost material such as carbon steel pipe for boiler header. The effect of chromium content on corrosion behavior of the weld was greater than that of the microstructure. The lifetime of the welded boiler can be increased by improvement of mechanical properties and corrosion behavior of the heat affected zone. PMID:28774014
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Apparatus for converting hydrocarbon fuel into hydrogen gas and carbon dioxide
Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.
2002-01-01
Hydrocarbon fuel reformer 100 suitable for producing synthesis hydrogen gas from reactions with hydrocarbons fuels, oxygen, and steam. A first tube 108 has a first tube inlet 110 and a first tube outlet 112. The first tube inlet 110 is adapted for receiving a first mixture including an oxygen-containing gas and a first fuel. A partially oxidized first reaction reformate is directed out of the first tube 108 into a mixing zone 114. A second tube 116 is annularly disposed about the first tube 108 and has a second tube inlet 118 and a second tube outlet 120. The second tube inlet 118 is adapted for receiving a second mixture including steam and a second fuel. A steam reformed second reaction reformate is directed out of the second tube 116 and into the mixing zone 114. From the mixing zone 114, the first and second reaction reformates may be directed into a catalytic reforming zone 144 containing a reforming catalyst 147.
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Confined polar mixtures within cylindrical nanocavities.
Rodriguez, Javier; Elola, M Dolores; Laria, Daniel
2010-06-17
Using molecular dynamics experiments, we have extended our previous analysis of equimolar mixtures of water and acetonitrile confined between silica walls [J. Phys. Chem. B 2009, 113, 12744] to examine similar solutions trapped within carbon nanotubes and cylindrical silica pores. Two different carbon tube sizes were investigated, (8,8) tubes, with radius R(cnt) = 0.55 nm, and (16,16) ones, with R(cnt) = 1.1 nm. In the narrowest tubes, we found that the cylindrical cavity is filled exclusively by acetonitrile; as the radius of the tube reaches approximately 1 nm, water begins to get incorporated within the inner cavities. In (16,16) tubes, the analysis of global and local concentration fluctuations shows a net increment of the global acetonitrile concentration; in addition, the aprotic solvent is also the prevailing species at the vicinity of the tube walls. Mixtures confined within silica nanopores of radius approximately 1.5 nm were also investigated. Three pores, differing in the effective wall/solvent interactions, were analyzed, (i) a first class, in which dispersive forces prevail (hydrophobic cavities), (ii) a second type, where oxygen sites at the pore walls are transformed into polar silanol groups (hydrophilic cavities), and (iii) finally, an intermediate scenario, in which 60% of the OH groups are replaced by mobile trimethylsilyl groups. Within the different pores, we found clear distinctions between the solvent layers that lie in close contact with the silica substrate and those with more central locations. Dynamical modes of the confined liquid phases were investigated in terms of diffusive and rotational time correlation functions. Compared to bulk results, the characteristic time scales describing different solvent motions exhibit significant increments. In carbon nanotubes, the most prominent modifications operate in the narrower tubes, where translations and rotations become severely hindered. In silica nanopores, the manifestations of the overall retardations are more dramatic for solvent species lying at the vicinity of trimethylsilyl groups.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Keiser, J.R.; Hubbard, C.R.; Payzant, E.A.
1997-04-01
Black liquor recovery boilers are essential components of kraft pulp and paper mills because they are a critical element of the system used to recover the pulping chemicals required in the kraft pulping process. In addition, the steam produced in these boilers is used to generate a significant portion of the electrical power used in the mill. Recovery boilers require the largest capital investment of any individual component of a paper mill, and these boilers are a major source of material problems in a mill. The walls and floors of these boilers are constructed of tube panels that circulate highmore » pressure water. Molten salts (smelt) accumulate on the floor of recovery boilers, and leakage of water into the boiler can result in a violent explosion when the leaked water instantly vaporizes upon contacting the molten smelt. Because corrosion of the conventionally-used carbon steel tubing was found to be excessive in the lower section of recovery boilers, use of stainless steel/carbon steel co-extruded tubing was adopted for boiler walls to lessen corrosion and reduce the likelihood of smelt/water explosions. Eventually, this co-extruded or composite (as it is known in the industry) tubing was selected for use as a portion or all of the floor of recovery boilers, particularly those operating at pressures > 6.2 MPa (900 psi), because of the corrosion problems encountered in carbon steel floor tubes. Since neither the cause of the cracking nor an effective solution has been identified, this program was established to develop a thorough understanding of the degradation that occurs in the composite tubing used for walls and floors. This is being accomplished through a program that includes collection and review of technical reports, examination of unexposed and cracked tubes from boiler floors, computer modeling to predict residual stresses under operating conditions, and operation of laboratory tests to study corrosion, stress corrosion cracking, and thermal fatigue.« less
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Shock Mitigation in Open-Celled TiNi Foams
NASA Astrophysics Data System (ADS)
Jardine, A. Peter
2018-05-01
High-energy shock events generated by impacts are effectively mitigated by Nitinol materials. Initial evidence of this capability was suggested by the dramatically superior cavitation-erosion performance of Nitinol coatings made by plasma spray processes, over steels and brasses. A fast acting hysteretic stress-strain response mechanism was proposed to explain this result, transforming the shock energy into heat. Extending this work to bulk TiNi, dynamic load characterization using Split Rod Hopkinson Bar techniques on solid porous TiNi confirmed that the mechanical response to high strain rates below 4200 s-1 were indeed hysteretic. This paper reports on dynamical load characterization on TiNi foams made by Self-Propagating High-Temperature Synthesis (SHS) using Split Rod Hopkinson Bar and gas-gun impact characterization to compare these foams to alternative materials. This work verified that SHS-derived TiNi foams were indeed hysteretic at strain rates from 180 to 2300 s-1. In addition, Shock Spectrum Analysis demonstrated that TiNi foams were very effective in mitigating the shock spectrum range below 5 kHz, and that increasing porosity increased the amount of shock attenuation in that spectral range. Finally under impact loading, 55% porous TiNi foams were a factor of 7 superior to steel and a factor of 4 better than Al 6061 or Cu in mitigating peak g-loads and this attenuation improved with bilayer structures of 57 and 73% porous TiNi foam article.
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2016-05-19
cycles at 100 mV/s scan rate. 15. SUBJECT TERMS Carbon nano tubes, Nanotechnology , supercapacitor 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...5. Lee, H., Hierarchical and Multifunctional Three-dimensional Network of Carbon Nanotubes of Sensor Applications, College of Engineering Forum on
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Prediction of Indentation Behavior of Superelastic TiNi
NASA Astrophysics Data System (ADS)
Neupane, Rabin; Farhat, Zoheir
2014-09-01
Superelastic TiNi shape memory alloys have been extensively used in various applications. The great interest in TiNi alloys is due to its unique shape memory and superelastic effects, along with its superior wear and dent resistance. Assessment of mechanical properties and dent resistance of superelastic TiNi is commonly performed using indentation techniques. However, the coupling of deformation and reversible martensitic transformation of TiNi under indentation conditions makes the interpretation of results challenging. An attempt is made to enhance current interpretation of indentation data. A load-depth curve is predicted that takes into consideration the reversible martensitic transformation. The predicted curve is in good agreement with experimental results. It is found in this study that the elastic modulus is a function of indentation depth. At shallow depths, the elastic modulus is high due to austenite dominance, while at high depths, the elastic modulus drops as the depth increases due to austenite to martensite transition, i.e., martensite dominance. It is also found that TiNi exhibits superior dent resistance compared to AISI 304 steel. There is two orders of magnitude improvement in dent resistance of TiNi in comparison to AISI 304 steel.
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NASA Astrophysics Data System (ADS)
Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus
2012-06-01
Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.
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Cathode readout with stripped resistive drift tubes
NASA Astrophysics Data System (ADS)
Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.
1994-11-01
A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH4. Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.
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Henry constant and isosteric heat at zero-loading for gas adsorption in carbon nanotubes.
Do, D D; Do, H D; Wongkoblap, A; Nicholson, D
2008-12-28
The Henry constant and the isosteric heat of adsorption at zero loading in a carbon nanotube bundle are studied with Monte Carlo integration for the adsorption of gases over a range of temperatures. The spacing between nanotubes in a bundle is determined from the minimization of potential energy of interaction between these tubes. We study different tube configurations with bundles of 2, 3, 4 and 7 tubes. Depending on the configuration it is found that the spacing is of between 0.31 to 0.333 nm, and this falls within the range reported in the literature. The Henry constant has been carefully defined so that it will not become negative at high temperatures. This is done with the aid of accessible volume, rather than the usual absolute void volume. We show that linearity of the van't Hoff plot for the Henry constant is not strictly followed. Furthermore the slope of this plot is not equal to the isosteric heat of adsorption at zero loading, which is found to be a strong function of temperature. From the results we find that the Henry constant and the heat of adsorption depend on the tube configuration. In general the adsorption in the cusp interstices is strongest followed by that inside the tube and finally on the outer surface. However for very small tubes adsorption occurs inside the tube first. For molecules with orientation, the behaviour is even more interesting and the shape of the isosteric heat versus temperature depends on the degree of orientation, tube configuration and the domain of adsorption (interstices, inside the tube and on the outer surface).
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2007-03-01
Stephenson Chemical Company, Inc. Carbon Nanotechnologies , Inc. 3 produced the multi-walled carbon nanotubes used in this study. The tube diameters range...5125-5132. 11. Kim S. , Pechar T. W. and Marand E., Desalination , 192(2006): 330-339 12. Cai H., Yan F. Y., and Xue Q. J., Materials Science and
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A case of simultaneous bilateral spontaneous pneumothorax after the Nuss procedure.
Matsuoka, Shunichiro; Miyazawa, Masahisa; Kashimoto, Kentaro; Kobayashi, Hiroaki; Mitsui, Fumihiko; Tsunoda, Hajime; Kunitomo, Kazuyoshi; Chisuwa, Hisanao; Haba, Yoshiaki
2016-06-01
We present a case of simultaneous bilateral spontaneous pneumothorax caused by a pleuro-pleural communication formed from Nuss procedure for pectus excavatum. A 17-year-old man with a history of Nuss operation complained chest pain and dyspnea. A chest roentgenogram demonstrated a tiny bilateral pneumothorax and two metallic bars inserted at the Nuss procedure. Computed tomography revealed furthermore a bulla in the apex of the left lung. The bilateral pneumothorax critically deteriorated after 4 days from onset and urgent bilateral chest drainages were performed. Nevertheless the drainages the full expansion of both lungs was not obtained and air leakage only from left side was continued. A video-assisted left bullectomy was performed 9 days after the tube insertion. The two bars penetrating anterior mediastinal pleura were thought to be a cause of the simultaneous bilateral spontaneous pneumothorax.
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Ti Ni shape memory alloy film-actuated microstructures for a MEMS probe card
NASA Astrophysics Data System (ADS)
Namazu, Takahiro; Tashiro, Youichi; Inoue, Shozo
2007-01-01
This paper describes the development of a novel silicon (Si) cantilever beam device actuated by titanium-nickel (Ti-Ni) shape memory alloy (SMA) films. A Ti-Ni SMA film can yield high work output per unit volume, so a Ti-Ni film-actuated Si cantilever beam device is a prospective tool for use as a microelectromechanical system (MEMS) probe card that provides a relatively large contact force between the probe and electrode pad in spite of its minute size. Before fabrication of the device, the thermomechanical deformation behavior of Ti-Ni SMA films with various compositions was investigated in order to determine a sufficient constituent film for a MEMS actuator. As a result, Ti-Ni films having a Ti content of 50.2 to 52.6 atomic% (at%) were found to be usable for operation as a room temperature actuator. We have developed a Ti-Ni film-actuated Si cantilever beam device, which can produce a contact force by the cantilever bending when in contact, and also by the shape memory effect (SME) of the Ti-Ni film arising from Joule heating. The SME of the Ti-Ni film can generate an additional average contact force of 200 µN with application of 500 mW to the film. In addition to physical contact, a dependable electric contact between the Au film-coated probe tip and the Al film electrode was achieved. However, the contact resistance exhibited an average value of 25 Ω, which would have to be reduced for practical use. Reliability tests confirmed the durability of the Ti-Ni film-actuated Si cantilever-beam, in that the contact resistance was constant throughout a large number of physical contacts (>104 times).
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Formation and Geological Sequestration of Uranium Nanoparticles in Deep Granitic Aquifer
Suzuki, Yohey; Mukai, Hiroki; Ishimura, Toyoho; Yokoyama, Takaomi D.; Sakata, Shuhei; Hirata, Takafumi; Iwatsuki, Teruki; Mizuno, Takashi
2016-01-01
The stimulation of bacterial activities that convert hexavalent uranium, U(VI), to tetravalent uranium, U(IV), appears to be feasible for cost-effective remediation of contaminated aquifers. However, U(VI) reduction typically results in the precipitation of U(IV) particles less than 5 nanometers in diameter, except for environmental conditions enriched with iron. Because these tiny particles are mobile and susceptible to oxidative dissolution after the termination of nutrient injection, in situ bioremediation remains to be impractical. Here we show that U(IV) nanoparticles of coffinite (U(SiO4)1−x(OH)4x) formed in fracture-filling calcium carbonate in a granitic aquifer. In situ U-Pb isotope dating demonstrates that U(IV) nanoparticles have been sequestered in the calcium carbonate for at least 1 million years. As the microbiologically induced precipitation of calcium carbonate in aquifer systems worldwide is extremely common, we anticipate simultaneous stimulation of microbial activities for precipitation reactions of calcium carbonate and U(IV) nanoparticles, which leads to long-term sequestration of uranium and other radionuclides in contaminated aquifers and deep geological repositories. PMID:26948389
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Formation and Geological Sequestration of Uranium Nanoparticles in Deep Granitic Aquifer.
Suzuki, Yohey; Mukai, Hiroki; Ishimura, Toyoho; Yokoyama, Takaomi D; Sakata, Shuhei; Hirata, Takafumi; Iwatsuki, Teruki; Mizuno, Takashi
2016-03-07
The stimulation of bacterial activities that convert hexavalent uranium, U(VI), to tetravalent uranium, U(IV), appears to be feasible for cost-effective remediation of contaminated aquifers. However, U(VI) reduction typically results in the precipitation of U(IV) particles less than 5 nanometers in diameter, except for environmental conditions enriched with iron. Because these tiny particles are mobile and susceptible to oxidative dissolution after the termination of nutrient injection, in situ bioremediation remains to be impractical. Here we show that U(IV) nanoparticles of coffinite (U(SiO4)1-x(OH)4x) formed in fracture-filling calcium carbonate in a granitic aquifer. In situ U-Pb isotope dating demonstrates that U(IV) nanoparticles have been sequestered in the calcium carbonate for at least 1 million years. As the microbiologically induced precipitation of calcium carbonate in aquifer systems worldwide is extremely common, we anticipate simultaneous stimulation of microbial activities for precipitation reactions of calcium carbonate and U(IV) nanoparticles, which leads to long-term sequestration of uranium and other radionuclides in contaminated aquifers and deep geological repositories.
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NASA Ocean Data Shows ‘Climate Dance’ of Plankton
2014-09-29
The greens and blues of the ocean color from NASA satellite data have provided new insights into how climate and ecosystem processes affect the growth cycles of phytoplankton—microscopic aquatic plants important for fish populations and Earth’s carbon cycle. At the bottom of the ocean’s food chain, phytoplankton account for roughly half of the net photosynthesis on Earth. Their photosynthesis consumes carbon dioxide and plays a key role in transferring carbon from the atmosphere to the ocean. Unlike the plant ecosystems on land, the amount of phytoplankton in the ocean is always followed closely by the abundance of organisms that eat phytoplankton, creating a perpetual dance between predators and prey. This new analysis shows how tiny imbalances in this predator-prey relationship, caused by environmental variability, give rise to massive phytoplankton blooms, having huge impacts on ocean productivity, fisheries and carbon cycling. The study was released Thursday, Sept. 25, in the journal Nature Climate Change. “The continuous year-in and year-out measurements provided by NASA’s ocean color satellites have dramatically changed our understanding of phytoplankton dynamics on the Earth,” said Mike Behrenfeld, author of the study and phytoplankton ecologist at Oregon State University, Corvallis, Oregon. “What we now see is a closely linked system of phytoplankton cell division and consumption lying at the heart of the plant’s annual cycle.” Behrenfeld calls this close predator-prey relationship the “Dance of the Plankton.” This view is different from previous perspectives that have simply focused on environmental resources used by phytoplankton to grow, such as nutrients and light. The new view is important because it reveals that tiny imbalances can greatly impact Earth’s ecology. Read more: 1.usa.gov/ZkVMHG Credit: NASA's Goddard Space Flight Center, Norman Kuring; USGS NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram
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Prevention of CO2 laser-induced endotracheal tube fires with the laser-guard protective coating.
Sosis, M B; Dillon, F
1992-01-01
To determine how well Laser-Guard protects polyvinyl chloride (PVC) endotracheal tubes from the carbon dioxide (CO2) laser. Bare and Laser-Guard-protected PVC endotracheal tubes were tested with 5 L/min of oxygen (O2) passing through them. Research laboratory of a university-affiliated metropolitan medical center. After moistening the Laser-Guard-protected endotracheal tubes, we subjected the tubes to CO2 laser radiation at 10 and 70 watts until combustion occurred or 60 seconds had elapsed. The bare PVC tube ignited and a "blowtorch" fire occurred after 3 seconds of CO2 laser use at 70 watts. The moistened Laser-Guard-protected PVC endotracheal tubes were not significantly damaged by 1 minute of laser use at 70 watts. Laser-Guard protects the shafts of combustible PVC endotracheal tubes from direct, high-power, continuous CO2 laser radiation.
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Mechanical and Electrical Properties of Organogels with Multiwall Carbon Nanotubes
NASA Astrophysics Data System (ADS)
Moniruzzaman, Mohammad; Winey, Karen
2008-03-01
Organogels are fascinating thermally reversible viscoelastic materials that are comprised of an organic liquid and low concentrations (typically <2 wt %) of low molecular mass organic gelators. We have fabricated the first organogel/carbon nanotube composites using 12-hydroxystearic acid (HSA) as the gelator molecule and pristine and carboxylated multi-wall carbon nanotubes as the nanofillers and 1,2-dichlorobenzene as the organic solvent. We have achieved significant improvements in the mechanical and electrical properties of organogels by incorporating these carbon nanotubes. For example, the linear viscoelastic regime of the HSA organogel, an indicator of the strength of the gel, extends by a factor of 4 with the incorporation of 0.2 wt% of the carboxylated nanotubes. Also, the carbon nanotubes (specially the pristine tubes) improve the electrical conductivity of the organogels, e.g. six orders of magnitude enhancement in electrical conductivity with 0.2 wt% of pristine tubes. Differential scanning calorimetry experiments indicate that the nanotubes do not affect the thermoreversibility of the organogels.
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Photoinduced Spontaneous Free-Carrier Generation in Semiconducting Single-Walled Carbon Nanotubes
Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.; ...
2015-11-04
The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less
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Elastocaloric cooling of additive manufactured shape memory alloys with large latent heat
Hou, Huilong; Simsek, Emrah; Stasak, Drew; ...
2017-08-11
The stress-induced martensitic phase transformation of shape memory alloys (SMAs) is the basis for elastocaloric cooling. In this paper, we employ additive manufacturing to fabricate TiNi SMAs, and demonstrate compressive elastocaloric cooling in the TiNi rods with transformation latent heat as large as 20 J g -1. Adiabatic compression on as-fabricated TiNi displays cooling ΔT as high as -7.5 °C with recoverable superelastic strain up to 5%. Unlike conventional SMAs, additive manufactured TiNi SMAs exhibit linear superelasticity with narrow hysteresis in stress–strain curves under both adiabatic and isothermal conditions. Microstructurally, we find that there are Ti 2Ni precipitates typically onemore » micron in size with a large aspect ratio enclosing the TiNi matrix. Finally, a stress transfer mechanism between reversible phase transformation in the TiNi matrix and mechanical deformation in Ti 2Ni precipitates is believed to be the origin of the unique superelasticity behavior.« less
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Zhang, Lei; Wu, Hao Bin; Lou, Xiong Wen
2012-07-14
Unusual CoS(2) ellipsoids with anisotropic tube-like cavities have been synthesized from the simultaneous thermal decomposition and sulfidation of a preformed cobalt carbonate precursor. The as-prepared CoS(2) ellipsoids show interesting supercapacitive properties with high capacitance and good cycling performance.
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Working cycles of devices based on bistable carbon nanotubes
NASA Astrophysics Data System (ADS)
Shklyaev, Oleg; Mockensturm, Eric; Crespi, Vincent; Carbon Nanotubes Collaboration
2013-03-01
Shape-changing nanotubes are an example of variable-shape sp2 carbon-based systems where the competition between strain and surface energies can be moderated by an externally controllable stimuli such as applied voltage, temperature, or pressure of gas encapsulated inside the tube. Using any of these stimuli one can transition a bistable carbon nanotube between the collapsed and inflated states and thus perform mechanical work. During the working cycle of such a device, energy from an electric or heat source is transferred to mechanical energy. Combinations of these stimuli allow the system to convert energy between different sources using the bistable shape-changing tube as a mediator. For example, coupling a bistable carbon nanotube to the heat and charge reservoirs can enable energy transfer between heat and electric forms. The developed theory can be extended to other nano-systems which change configurations in response to external stimuli.
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Deformation and Failure of a Multi-Wall Carbon Nanotube Yarn Composite
NASA Technical Reports Server (NTRS)
Gates, Thomas S.; Jefferson, Gail D.; Frankland, Sarah-Jane V.
2008-01-01
Forests of multi-walled carbon nanotubes can be twisted and manipulated into continuous fibers or yarns that exhibit many of the characteristics of traditional textiles. Macro-scale analysis and test may provide strength and stiffness predictions for a composite composed of a polymer matrix and low-volume fraction yarns. However, due to the nano-scale of the carbon nanotubes, it is desirable to use atomistic calculations to consider tube-tube interactions and the influence of simulated twist on the effective friction coefficient. This paper reports laboratory test data on the mechanical response of a multi-walled, carbon nanotube yarn/polymer composite from both dynamic and quasi-static tensile tests. Macroscale and nano-scale analysis methods are explored and used to define some of the key structure-property relationships. The measured influence of hot-wet aging on the tensile properties is also reported.
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Filling carbon nanotubes with particles.
Kim, Byong M; Qian, Shizhi; Bau, Haim H
2005-05-01
The filling of carbon nanotubes (CNTs) with fluorescent particles was studied experimentally and theoretically. The fluorescent signals emitted by the particles were visible through the walls of the nanotubes, and the particles inside the tubes were observable with an electron microscope. Taking advantage of the template-grown carbon nanotubes' transparency to fluorescent light, we measured the filling rate of the tubes with particles at room conditions. Liquids such as ethylene glycol, water, and ethylene glycol/water mixtures, laden with 50 nm diameter fluorescent particles, were brought into contact with 500 nm diameter CNTs. The liquid and the particles' transport were observed, respectively, with optical and fluorescence microscopy. The CNTs were filled controllably with particles by the complementary action of capillary forces and the evaporation of the liquid. The experimental results were compared and favorably agreed with theoretical predictions. This is the first report on fluorescence studies of particle transport in carbon nanotubes.
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Khalili, V; Khalil-Allafi, J; Frenzel, J; Eggeler, G
2017-02-01
In order to improve the surface bioactivity of NiTi bone implant and corrosion resistance, hydroxyapatite coating with addition of 20wt% silicon, 1wt% multi walled carbon nano-tubes and both of them were deposited on a NiTi substrate using a cathodic electrophoretic method. The apatite formation ability was estimated using immersion test in the simulated body fluid for 10days. The SEM images of the surface of coatings after immersion in simulated body fluid show that the presence of silicon in the hydroxyapatite coatings accelerates in vitro growth of apatite layer on the coatings. The Open-circuit potential and electrochemical impedance spectroscopy were measured to evaluate the electrochemical behavior of the coatings in the simulated body fluid at 37°C. The results indicate that the compact structure of hydroxyapatite-20wt% silicon and hydroxyapatite-20wt% silicon-1wt% multi walled carbon nano-tubes coatings could efficiently increase the corrosion resistance of NiTi substrate. Copyright © 2016 Elsevier B.V. All rights reserved.
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Evaluation of Heat Transfer and Thermal Stability of Supercritical JP-7 Fuel
NASA Technical Reports Server (NTRS)
Linne, Diane L.; Meyer, Michael L.; Edwards, Tim; Eitman, David A.
1997-01-01
A series of electrically heated tube experiments was conducted to investigate the potential of JP-7 as a coolant under conditions relevant to a Mach 8 propulsion system. The heat transfer capabilities, carbon deposition, and material compatibility of JP-7 at surface temperatures up to 1700 F (927 C) were tested in 0.125 in. diameter tubes of 304 SS, Inconel 617, Haynes 188, Haynes 230, and 50150 Moly-Rhenium. The heat transfer to the coolant was modeled well by a Dittus-Boelter correlation at lower heat fluxes. At higher heat fluxes, audible instabilities were observed and corresponded to a significant enhancement in the coolant heat transfer. The carbon deposition rates in these tests were comparable to those in previous experiments at lower heat fluxes and much longer residence times. This result suggests that alternative paths of the deposition mechanism may be enhanced under high heat flux test conditions. Microscopic investigation of the post test tubes indicated that there was a significant layer of ordered carbon deposits that had not been seen in the tests at lower heat flux.
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A quantum chemistry study on surface reactivity of pristine and carbon-substituted AlN nanotubes
NASA Astrophysics Data System (ADS)
Mahdaviani, Amir; Esrafili, Mehdi D.; Esrafili, Ali; Behzadi, Hadi
2013-09-01
A density functional theory investigation was performed to predict the surface reactivity of pristine and carbon-substituted (6,0) single-walled aluminum nitride nanotubes (AlNNTs). The properties determined include the electrostatic potentials VS(r) and average local ionization energies ĪS(r) on the surfaces of the investigated tubes. According to computed VS(r) results, the Al/N atoms in edge or cap regions show a different reactivity pattern than those at the middle portion of the tubes. Due to the carbon-substitution at the either Al or N sites of the tubes, the negative regions associated with nitrogen atoms are stronger than before. The prediction of surface reactivity and regioselectivity using average local ionization energies has been verified by atomic hydrogen chemisorption energies calculated for AlNNTs at the B3LYP/6-31 G* level. There is an acceptable correlation between the minima of ĪS(r) and the atomic hydrogen chemisorption energies, demonstrating that ĪS(r) provides an effective means for rapidly and economically assessing the relative reactivities of finite sized AlNNTs.
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NASA Astrophysics Data System (ADS)
Alaf, M.; Gultekin, D.; Akbulut, H.
2013-06-01
Free-standing multiwalled carbon nano tube papers (buckypapers) were prepared by vacuum filtration from functionalized multi walled carbon nano tubes (MWCNTs) with controlling porosity. Double phase matrix Sn/SnO2/MWCNT nanocomposites were obtained in two steps, including thermal evaporation of metallic tin (Sn) on the MWCNT papers and RF plasma oxidation. The ratio between metallic tin (Sn) and tin oxide (SnO2) was controlled with plasma oxidation time. It was determined that the evaporated pure tin nano crystals were mechanically penetrated into pores of buckypapers to form functionally gradient nanocomposites. Sn/SnO2 coated on MWCNT buckypapers were used as working electrodes in assembled as coin-type (CR2016) test cells. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine the structure and morphology of the obtained nanocomposites. In addition, the discharge/charge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out to characterize the electrochemical properties of these composites as anode materials for Li-ion batteries.
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Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing
2018-01-01
In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9% and nitrogen (N) doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g -1 , it still delivers a high discharge capacity of 329 mA h g -1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.
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NASA Astrophysics Data System (ADS)
Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing
2018-04-01
In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9 % and nitrogen (N) doping of as high as 15.5 %, in which the electrochemically active N accounts for 84 % of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g-1, it still delivered a high discharge capacity of 329 mA h g-1 after 1000 cycles. First principle calculations verified that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.
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Robertson, J.F.; Aelion, C.M.; Vroblesky, D.A.
1993-01-01
Two passive soil-vapor sampling techniques were used in the vicinity of a defense fuel supply point in Hanahan, South Carolina, to identify areas of potential contamination of the shallow water table aquifer by volatile organic compounds (VOC's). Both techniques involved the burial of samplers in the vadose zone and the saturated bottom sediments of nearby streams. One method, the empty-tube technique, allowed vapors to pass through a permeable membrane and accumulate inside an inverted empty test tube. A sample was extracted and analyzed on site by using a portable gas chromatograph. As a comparison to this method, an activated-carbon technique, also was used in certain areas. This method uses a vapor collector consisting of a test tube containing activated carbon as a sorbent for VOC's.
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-03-10
... Carbon and Alloy Seamless Standard, Line, and Pressure Pipe From Japan: Extension of Time Limit for... review of the antidumping duty order on certain large diameter carbon and alloy seamless standard, line... manufacturers/exporters: JFE Steel Corporation; Nippon Steel Corporation; NKK Tubes; and Sumitomo Metal...
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NASA Astrophysics Data System (ADS)
Pak, Arthur; Benedetti, L. R.; Berzak Hopkins, L. F.; Clark, D.; Divol, L.; Dewald, E. L.; Fittinghoff, D.; Izumi, N.; Khan, S. F.; Landen, O.; Lepape, S.; Ma, T.; Marley, E.; Nagel, S.; Volegov, P.; Weber, C.; Bradley, D. K.; Callahan, D.; Grim, G.; Hurricane, O. A.; Patel, P.; Schneider, M. B.; Edwards, M. J.
2017-10-01
In recent inertial confinement implosion experiments conducted at the National Ignition Facility, bright and spatially localized x-ray emission within the hot spot at stagnation has been observed. This emission is associated with higher Z ablator material that is injected into the hot spot by the hydrodynamic perturbation induced by the 5-10 um diameter capsule fill tube. The reactivity of the DT fuel and subsequent yield of the implosion are strongly dependent on the density, temperature, and confinement time achieved throughout the stagnation of the implosion. Radiative losses from higher Z ablator material that mixes into the hot spot as well as non-uniformities in the compression and confinement induced by the fill tube perturbation can degrade the yield of the implosion. This work will examine the impact to conditions at stagnation that results from the fill tube perturbation. This assessment will be based from a pair of experiments conducted with a high density carbon ablator where the only deliberate change was reduction in fill tube diameter from 10 to 5 um. An estimate of the radiative losses and impact on performance from ablator mix injected into the hot spot by the fill tube perturbation will be presented. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ortega, Jesus; Khivsara, Sagar; Christian, Joshua
A supercritical carbon dioxide (sCO 2) Brayton cycle is an emerging high energy-density cycle undergoing extensive research due to the appealing thermo-physical properties of sCO 2 and single phase operation. Development of a solar receiver capable of delivering sCO 2 at 20 MPa and 700 °C is required for implementation of the high efficiency (~50%) solar powered sCO 2 Brayton cycle. In this work, extensive candidate materials are review along with tube size optimization using the ASME Boiler and Pressure Vessel Code. Moreover, temperature and pressure distribution obtained from the thermal-fluid modeling (presented in a complementary publication) are used tomore » evaluate the thermal and mechanical stresses along with detailed creep-fatigue analysis of the tubes. The lifetime performance of the receiver tubes were approximated using the resulting body stresses. A cyclic loading analysis is performed by coupling the Strain-Life approach and the Larson-Miller creep model. The structural integrity of the receiver was examined and it was found that the stresses can be withstood by specific tubes, determined by a parametric geometric analysis. Furthermore, the creep-fatigue analysis displayed the damage accumulation due to cycling and the permanent deformation on the tubes showed that the tubes can operate for the full lifetime of the receiver.« less
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Ortega, Jesus; Khivsara, Sagar; Christian, Joshua; ...
2016-06-06
A supercritical carbon dioxide (sCO 2) Brayton cycle is an emerging high energy-density cycle undergoing extensive research due to the appealing thermo-physical properties of sCO 2 and single phase operation. Development of a solar receiver capable of delivering sCO 2 at 20 MPa and 700 °C is required for implementation of the high efficiency (~50%) solar powered sCO 2 Brayton cycle. In this work, extensive candidate materials are review along with tube size optimization using the ASME Boiler and Pressure Vessel Code. Moreover, temperature and pressure distribution obtained from the thermal-fluid modeling (presented in a complementary publication) are used tomore » evaluate the thermal and mechanical stresses along with detailed creep-fatigue analysis of the tubes. The lifetime performance of the receiver tubes were approximated using the resulting body stresses. A cyclic loading analysis is performed by coupling the Strain-Life approach and the Larson-Miller creep model. The structural integrity of the receiver was examined and it was found that the stresses can be withstood by specific tubes, determined by a parametric geometric analysis. Furthermore, the creep-fatigue analysis displayed the damage accumulation due to cycling and the permanent deformation on the tubes showed that the tubes can operate for the full lifetime of the receiver.« less
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Feng, Juanjuan; Wang, Xiuqin; Tian, Yu; Bu, Yanan; Luo, Chuannan; Sun, Min
2017-09-29
Carbon fibers (CFs) were functionalized with graphene oxide (GO) by an electrophoretic deposition (EPD) method for in-tube solid-phase microextraction (SPME). GO-CFs were filled into a poly(ether ether ketone) (PEEK) tube to obtain a fibers-in-tube SPME device, which was connected with high performance liquid chromatography (HPLC) equipment to build online SPME-HPLC system. Compared with CFs, GO-CFs presented obviously better extraction performance, due to excellent adsorption property and large surface area of GO. Using ten polycyclic aromatic hydrocarbons (PAHs) as model analytes, the important extraction conditions were optimized, such as sample flow rate, extraction time, organic solvent content and desorption time. An online analysis method was established with wide linear range (0.01-50μgL -1 ) and low detection limits (0.001-0.004μgL -1 ). Good sensitivity resulted from high enrichment factors (1133-3840) of GO-CFs in-tube device towards PAHs. The analysis method was used to online determination of PAHs in wastewater samples. Some target analytes were detected and relative recoveries were in the range of 90.2-112%. It is obvious that the proposed GO-CFs in-tube device was an efficient extraction device, and EPD could be used to develop nanomaterials functionalized sorbents for sample preparation. Copyright © 2017 Elsevier B.V. All rights reserved.
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Marchewka, W.; Mohamed, K.; Addis, J.; Karnack, F.
2015-01-01
A tube bundle system (TBS) is a mechanical system for continuously drawing gas samples through tubes from multiple monitoring points located in an underground coal mine. The gas samples are drawn via vacuum pump to the surface and are typically analyzed for oxygen, methane, carbon dioxide and carbon monoxide. Results of the gas analyses are displayed and recorded for further analysis. Trends in the composition of the mine atmosphere, such as increasing methane or carbon monoxide concentration, can be detected early, permitting rapid intervention that prevents problems, such as a potentially explosive atmosphere behind seals, fire or spontaneous combustion. TBS is a well-developed technology and has been used in coal mines around the world for more than 50 years. Most longwall coal mines in Australia deploy a TBS, usually with 30 to 40 monitoring points as part of their atmospheric monitoring. The primary uses of a TBS are detecting spontaneous combustion and maintaining sealed areas inert. The TBS might also provide mine atmosphere gas composition data after a catastrophe occurs in an underground mine, if the sampling tubes are not damaged. TBSs are not an alternative to statutory gas and ventilation airflow monitoring by electronic sensors or people; rather, they are an option to consider in an overall mine atmosphere monitoring strategy. This paper describes the hardware, software and operation of a TBS and presents one example of typical data from a longwall coal mine PMID:26306052
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Tube bundle system: for monitoring of coal mine atmosphere.
Zipf, R Karl; Marchewka, W; Mohamed, K; Addis, J; Karnack, F
2013-05-01
A tube bundle system (TBS) is a mechanical system for continuously drawing gas samples through tubes from multiple monitoring points located in an underground coal mine. The gas samples are drawn via vacuum pump to the surface and are typically analyzed for oxygen, methane, carbon dioxide and carbon monoxide. Results of the gas analyses are displayed and recorded for further analysis. Trends in the composition of the mine atmosphere, such as increasing methane or carbon monoxide concentration, can be detected early, permitting rapid intervention that prevents problems, such as a potentially explosive atmosphere behind seals, fire or spontaneous combustion. TBS is a well-developed technology and has been used in coal mines around the world for more than 50 years. Most longwall coal mines in Australia deploy a TBS, usually with 30 to 40 monitoring points as part of their atmospheric monitoring. The primary uses of a TBS are detecting spontaneous combustion and maintaining sealed areas inert. The TBS might also provide mine atmosphere gas composition data after a catastrophe occurs in an underground mine, if the sampling tubes are not damaged. TBSs are not an alternative to statutory gas and ventilation airflow monitoring by electronic sensors or people; rather, they are an option to consider in an overall mine atmosphere monitoring strategy. This paper describes the hardware, software and operation of a TBS and presents one example of typical data from a longwall coal mine.
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NASA Astrophysics Data System (ADS)
Mazlan, N.; Jaafar, M.; Aziz, A.; Ismail, H.; Busfield, J. J. C.
2016-10-01
In this work, two different processing techniques were approached to identify the properties of the multi-walled carbon nanotubes (MWCNT) reinforced polydimethylsiloxane (PDMS). The MWCNT was dispersed in the polymer by using the ultrasonic and twin screw extruder mixer. The final composite showed different manner of dispersed tubes in the silicone rubber matrix. High shear twin screw extruder tends to fragment the tubes during processing compound, which can be observed by scanning electron microscope (SEM). Tensile strength of the extrusion MWCNT/PDMS nanocomposites was found to be higher compared to ultrasonic MWCNT/PDMS nanocomposites.
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NASA Astrophysics Data System (ADS)
Ci, Lijie; Zhou, Zhenping; Yan, Xiaoqin; Liu, Dongfang; Yuan, Huajun; Song, Li; Gao, Yan; Wang, Jianxiong; Liu, Lifeng; Zhou, Weiya; Wang, Gang; Xie, Sishen; Tan, Pingheng
2003-11-01
Resonant Raman spectra of double wall carbon nanotubes (DWCNTs), with diameters from 0.4 to 3.0 nm, were investigated with several laser excitations. The peak position and line shape of Raman bands were shown to be strongly dependent on the laser energies. With different excitations, the diameter and chirality of the DWCNTs can be discussed in detail. We show that tubes (the inner or outer layers of DWCNTs) with all kinds of chiralities could be synthesized, and a DWCNT can have any combination of chiralities of the inner and outer tubes.
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A TinyOS-based wireless neural interface.
Farshchi, Shahin; Mody, Istvan; Judy, Jack W
2004-01-01
The overlay of a neural interface upon a TinyOS-based sensing and communication platform is described. The system amplifies, digitally encodes, and transmits two EEG channels of neural signals from an un-tethered subject to a remote gateway, which routes the signals to a client PC. This work demonstrates the viability of the TinyOS-based sensor technology as a foundation for chronic remote biological monitoring applications, and thus provides an opportunity to create a system that can leverage from the frequent networking and communications advancements being made by the global TinyOS-development community.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Keiser, J.R.; Taljat, B.; Wang, X.L.
Cracking of co-extruded (generally identified as composite) floor tubes in kraft black liquor recovery boilers was first observed in Scandinavia, but this problem has now been found in many North American boilers. In most cases, cracking in the outer 304L stainless steel has not progressed into the carbon steel, but the potential for such crack propagation is a cause of concern. A multidimensional study has been initiated to characterize the cracking seen in composite floor tubes, to measure the residual stresses resulting from composite tube fabrication, and to predict the stresses in tubes under operating conditions. The characterization studies includemore » review of available reports and documents on composite tube cracking, metallographic examination of a substantial number of cracked tubes, and evaluation of the dislocation structure in cracked tubes. Neutron and X-ray diffraction are being used to determine the residual stresses in composite tubes from two major manufacturers, and finite element analysis is being used to predict the stresses in the tubes during normal operation and under conditions where thermal fluctuations occur.« less
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Carbon nanotubes from synthesis to in vivo biomedical applications.
Sajid, Muhammad Imran; Jamshaid, Usama; Jamshaid, Talha; Zafar, Nadiah; Fessi, H; Elaissari, Abdelhamid
2016-03-30
Owing to their unique and interesting properties, extensive research round the globe has been carried out on carbon nanotubes and carbon nanotubes based systems to investigate their practical usefulness in biomedical applications. The results from these studies demonstrate a great promise in their use in targeted drug delivery systems, diagnostic techniques and in bio-analytical applications. Although, carbon nanotubes possess quite interesting properties, which make them potential candidates in the biomedical science, but they also have some inherent properties which arise great concern regarding their biosafety. In this comprehensive review, we have discussed different aspects of carbon nanotubes and carbon nanotube based systems related to biomedical applications. In the beginning, a short historical account of these tiny yet powerful particles is given followed by discussion regarding their types, properties, methods of synthesis, large scale production method, purification techniques and characterization aspects of carbon nanotubes. In the second part of the review, the functionalization of carbon nanotubes is reviewed in detail, which is not only important to make them biocompatible and stable in biological systems but also render them a great property of loading various biomolecules, diagnostic and therapeutic moieties resulting in diversified applications. In the final part of the review, emphasis is given on the pharmacokinetic aspects of carbon nanotubes including administration routes, absorption mechanisms, distribution and elimination of carbon nanotubes based systems. Lastly, a comprehensive account about the potential biomedical applications has been given followed by insights into the future. Copyright © 2016 Elsevier B.V. All rights reserved.
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Tiny bubbles challenge giant turbines: Three Gorges puzzle.
Li, Shengcai
2015-10-06
Since the birth of the first prototype of the modern reaction turbine, cavitation as conjectured by Euler in 1754 always presents as a challenge. Following his theory, the evolution of modern reaction (Francis and Kaplan) turbines has been completed by adding the final piece of the element 'draft-tube' that enables turbines to explore water energy at efficiencies of almost 100%. However, during the last two and a half centuries, with increasing unit capacity and specific speed, the problem of cavitation has been manifested and complicated by the draft-tube surges rather than being solved. Particularly, during the last 20 years, the fierce competition in the international market for extremely large turbines with compact design has encouraged the development of giant Francis turbines of 700-1000 MW. The first group (24 units) of such giant turbines of 700 MW each was installed in the Three Gorges project. Immediately after commission, a strange erosion phenomenon appeared on the guide vane of the machines that has puzzled professionals. From a multi-disciplinary analysis, this Three Gorges puzzle could reflect an unknown type of cavitation inception presumably triggered by turbulence production from the boundary-layer streak transitional process. It thus presents a fresh challenge not only to this old turbine industry, but also to the fundamental sciences.
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NASA Astrophysics Data System (ADS)
Koley, Susmita; Ghosh, Indranil
Quick and periodic inflow-outflow of adsorbate in an adsorbent column createsa differential temperature between the two ends of it, allowing for the generation of continuous sorption cooling in a single adsorbent tube. The concept has been proven experimentally and theoretically for near room temperature applications using activated carbon-nitrogen. The feasibility of generating continuous solid sorption cooling in a single adsorbent tube in the cryogenic domainhas been studied theoretically with a different adsorbent-adsorbate pair, namely, activated carbon-hydrogen. Precooling of gaseous hydrogen (before it enters the adsorbent column) and removal of the heat of adsorption has been achieved using liquid nitrogen. Theoretical estimation shows nearly 20 K temperature difference between the two ends under no load condition. Finally, parametric variations have been performed.
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Method and apparatus for converting hydrocarbon fuel into hydrogen gas and carbon dioxide
Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H.J.
2000-01-01
An apparatus and a method are disclosed for converting hydrocarbon fuel or an alcohol into hydrogen gas and carbon dioxide. The apparatus includes a first vessel having a partial oxidation reaction zone and a separate steam reforming reaction zone that is distinct from the partial oxidation reaction zone. The first vessel has a first vessel inlet at the partial oxidation reaction zone and a first vessel outlet at the steam reforming zone. The reformer also includes a helical tube extending about the first vessel. The helical tube has a first end connected to an oxygen-containing source and a second end connected to the first vessel at the partial oxidation reaction zone. Oxygen gas from an oxygen-containing source can be directed through the helical tube to the first vessel. A second vessel having a second vessel inlet and second vessel outlet is annularly disposed about the first vessel. The helical tube is disposed between the first vessel and the second vessel and gases from the first vessel can be directed through second vessel.
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Active Metal Brazing and Characterization of Brazed Joints in Titanium to Carbon-Carbon Composites
NASA Technical Reports Server (NTRS)
Singh, M.; Shpargel, T. P.; Morscher, G. N.; Asthana, R.
2006-01-01
The Ti-metal/C-C composite joints were formed by reactive brazing with three commercial brazes, namely, Cu-ABA, TiCuNi, and TiCuSiI. The joint microstructures were examined using optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). The results of the microstructure analysis indicate solute redistribution across the joint and possible metallurgical bond formation via interdiffusion, which led to good wetting and spreading. A tube-on-plate tensile test was used to evaluate joint strength of Ti-tube/ C-C composite joints. The load-carrying ability was greatest for the Cu-ABA braze joint structures. This system appeared to have the best braze spreading which resulted in a larger braze/C-C composite bonded area compared to the other two braze materials. Also, joint loadcarrying ability was found to be higher for joint structures where the fiber tows in the outer ply of the C-C composite were aligned perpendicular to the tube axis when compared to the case where fiber tows were aligned parallel to the tube axis.
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Bao, Hua; Ruan, Xiulin; Fisher, Timothy S
2010-03-15
A finite-difference time-domain (FDTD) method is used to model thermal radiative properties of vertical arrays of multi-walled carbon nanotubes (MWCNT). Individual CNTs are treated as solid circular cylinders with an effective dielectric tensor. Consistent with experiments, the results confirm that CNT arrays are highly absorptive. Compared with the commonly used Maxwell-Garnett theory, the FDTD calculations generally predict larger reflectance and absorbance, and smaller transmittance, which are attributed to the diffraction and scattering within the cylinder array structure. The effects of volume fraction, tube length, tube distance, and incident angle on radiative properties are investigated systematically. Low volume fraction and long tubes are more favorable to achieve low reflectance and high absorbance. For a fixed volume fraction and finite tube length, larger periodicity results in larger reflectance and absorbance. The angular dependence studies reveal an optimum incident angle at which the reflectance can be minimized. The results also suggest that an even darker material could be achieved by using CNTs with good alignment on the top surface.
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Micromirror structure based on TiNi shape memory thin films
NASA Astrophysics Data System (ADS)
Fu, Yong Qing; Hu, Min; Du, Hejun; Luo, Jack; Flewitt, Andrew J.; Milne, William I.
2005-02-01
TiNi films were deposited on silicon by co-sputtering TiNi target and a separate Ti target at a temperature of 450°C. Results from differential scanning calorimeter, in-situ X-ray diffraction and curvature measurement revealed clearly martensitic transformation upon heating and cooling. Two types of TiNi/Si optical micromirror structures with a Si mirror cap (20 micron thick) and TiNi/Si actuation beams were designed and fabricated. For the first design, three elbow shaped Si beams with TiNi electrodes were used as the arms to actuate the mirror. In the second design, a V-shaped cantilever based on TiNi/Si bimorph beams was used as the actuation mechanism for micromirror. TiNi electrodes were patterned and wet-etched in a solutions of HF:HNO3:H2O (1:1:20) with an etch rate of 0.6 μm/min. The TiNi/Si microbeams were flat at room temperature, and bent up with applying voltage in TiNi electrodes (due to phase transformation and shape memory effect), thus causing the changes in angles of micromirror.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-07-26
... duty order on seamless carbon and alloy steel standard, line, and pressure pipe from the People's... the antidumping duty order on seamless carbon and alloy steel standard, line, and pressure pipe from... Making Co., Ltd.; Wuxi Seamless Special Pipe Co., Ltd.; Wuxi Sifang Steel Tube Co., Ltd.; Wuxi Zhenda...
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The purpose of this SOP is to describe the methodology for the analysis of certain trace volatile organic compounds (VOCs) in air that are captured on two-phase carbon-based multisorbent tubes packed with Carbotrap (graphitized carbon blacks) and Carbosieve S-III (a carbon molecu...
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The purpose of this SOP is to describe the methodology for the analysis of certain trace volatile organic compounds (VOCs) in air that are captured on carbon-based multisorbent tubes packed with Carbotrap C, Carbotrap (graphitized carbon blacks), and Carbosieve S-III (a carbon mo...
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Growth of High Quality Carbon Nanotubes on Free Standing Diamond Substrates
2010-01-01
CNTs forming a mat of ~5 µm thickness and consisting of ~20 nm diameter tubes were observed to grow in a thermal CVD system using C2H2 as precursor...with CNT microfin architectures have been recently proposed by Kordas et al. [5]. CNT films as thermal interface materials were also discussed by Zhu...using a 1 inch diameter quartz tube in a horizontal furnace. Initially, the tube furnace was evacuated by using a rough pump and then purged with Ar
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NASA Astrophysics Data System (ADS)
Mousa, M. S.; Bani Ali, E. S.; Hagmann, M. J.
2018-02-01
In this study, NanocylTM NC 7000 Thin Multiwall Carbon Nanotubes (MWCNTs) were used with a high aspect ratio (>150) made by the process of catalytic chemical vapor deposition (CCVD). The field emitter tips were prepared by inserting these MWCT into fine glass capillary tubes that were pulled at high temperatures and then cut. Measurements were carried out under ultra-high vacuum (UHV) conditions with a base pressure of 10-9 mbar. The data show the effects of initial conditioning of MWCNT and hysteresis. Compression of the MWCNT by the capillary tubes appears to provide adequate mechanical support without requiring the use of a low-melting point electrically-conductive binder as has been used previously. Emission currents in excess of 1 μA were obtained so this technique shows promise as a reliable, stable, powerful electron source.
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Konik, Robert M.; Sfeir, Matthew Y.; Misewich, James A.
2015-02-17
We demonstrate that a non-perturbative framework for the treatment of the excitations of single walled carbon nanotubes based upon a field theoretic reduction is able to accurately describe experiment observations of the absolute values of excitonic energies. This theoretical framework yields a simple scaling function from which the excitonic energies can be read off. This scaling function is primarily determined by a single parameter, the charge Luttinger parameter of the tube, which is in turn a function of the tube chirality, dielectric environment, and the tube's dimensions, thus expressing disparate influences on the excitonic energies in a unified fashion. Asmore » a result, we test this theory explicitly on the data reported in [NanoLetters 5, 2314 (2005)] and [Phys. Rev. B 82, 195424 (2010)] and so demonstrate the method works over a wide range of reported excitonic spectra.« less
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NASA Astrophysics Data System (ADS)
Zhen, Ya-Xin
2017-02-01
In this paper, the transverse wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes is investigated based on nonlocal elasticity theory with consideration of surface effect. The governing equation is formulated utilizing nonlocal Euler-Bernoulli beam theory and Kelvin-Voigt model. Explicit wave dispersion relation is developed and wave phase velocities and frequencies are obtained. The effect of the fluid flow velocity, structural damping, surface effect, small scale effects and tube diameter on the wave propagation properties are discussed with different wave numbers. The wave frequency increases with the increase of fluid flow velocity, but decreases with the increases of tube diameter and wave number. The effect of surface elasticity and residual surface tension is more significant for small wave number and tube diameter. For larger values of wave number and nonlocal parameters, the real part of frequency ratio raises.
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Method And Apparatus For Converting Hydrocarbon Fuel Into Hydrogen Gas And Carbon Dioxide
Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.
2000-09-26
A method is disclosed for synthesizing hydrogen gas from hydrocarbon fuel. A first mixture of steam and a first fuel is directed into a first tube 208 to subject the first mixture to a first steam reforming reaction in the presence of a first catalyst 214. A stream of oxygen-containing gas is pre-heated by transferring heat energy from product gases. A second mixture of the pre-heated oxygen-containing gas and a second fuel is directed into a second tube 218 disposed about the first tube 208 to subject the second mixture to a partial oxidation reaction and to provide heat energy for transfer to the first tube 208. A first reaction reformate from the first tube 208 and a second reaction reformate from the second tube 218 are directed into a third tube 224 disposed about the second tube 218 to subject the first and second reaction reformates to a second steam reforming reaction, wherein heat energy is transferred to the third tube 224 from the second tube 218.
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Design of a ram accelerator mass launch system
NASA Technical Reports Server (NTRS)
Aarnio, Michael; Armerding, Calvin; Berschauer, Andrew; Christofferson, Erik; Clement, Paul; Gohd, Robin; Neely, Bret; Reed, David; Rodriguez, Carlos; Swanstrom, Fredrick
1988-01-01
The ram accelerator mass launch system has been proposed to greatly reduce the costs of placing acceleration-insensitive payloads into low earth orbit. The ram accelerator is a chemically propelled, impulsive mass launch system capable of efficiently accelerating relatively large masses from velocities of 0.7 km/sec to 10 km/sec. The principles of propulsion are based on those of a conventional supersonic air-breathing ramjet; however the device operates in a somewhat different manner. The payload carrying vehicle resembles the center-body of the ramjet and accelerates through a stationary tube which acts as the outer cowling. The tube is filled with premixed gaseous fuel and oxidizer mixtures that burn in the vicinity of the vehicle's base, producing a thrust which accelerates the vehicle through the tube. This study examines the requirement for placing a 2000 kg vehicle into a 500 km circular orbit with a minimum amount of on-board rocket propellant for orbital maneuvers. The goal is to achieve a 50 pct payload mass fraction. The proposed design requirements have several self-imposed constraints that define the vehicle and tube configurations. Structural considerations on the vehicle and tube wall dictate an upper acceleration limit of 1000 g's and a tube inside diameter of 1.0 m. In-tube propulsive requirements and vehicle structural constraints result in a vehicle diameter of 0.76 m, a total length of 7.5 m and a nose-cone half angle of 7 degrees. An ablating nose-cone constructed from carbon-carbon composite serves as the thermal protection mechanism for atmospheric transit.
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NASA Technical Reports Server (NTRS)
Garfinkle, M.
1974-01-01
The tensile properties and oxygen contamination behavior of TiNi alloyed with aluminum, chromium, and silicon were investigated in the temperature range between 800 and 1000 K (980 and 1340 F). The alloys were significantly stronger than unalloyed TiNi and less susceptible to embrittlement than the Ti-6242 alloy.
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NASA Astrophysics Data System (ADS)
Huang, Jian Yu; Lo, Yu-Chieh; Niu, Jun Jie; Kushima, Akihiro; Qian, Xiaofeng; Zhong, Li; Mao, Scott X.; Li, Ju
2013-04-01
The ability to form tiny droplets of liquids and control their movements is important in printing or patterning, chemical reactions and biological assays. So far, such nanofluidic capabilities have principally used components such as channels, nozzles or tubes, where a solid encloses the transported liquid. Here, we show that liquids can flow along the outer surface of solid nanowires at a scale of attolitres per second and the process can be directly imaged with in situ transmission electron microscopy. Microscopy videos show that an ionic liquid can be pumped along tin dioxide, silicon or zinc oxide nanowires as a thin precursor film or as beads riding on the precursor film. Theoretical analysis suggests there is a critical film thickness of ~10 nm below which the liquid flows as a flat film and above which it flows as discrete beads. This critical thickness is the result of intermolecular forces between solid and liquid, which compete with liquid surface energy and Rayleigh-Plateau instability.
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Structural and Acoustic Damping Characteristics of Polyimide Microspheres
NASA Technical Reports Server (NTRS)
Palumbo, Daniel L.; Park, Junhong
2005-01-01
A broad range of tests have been performed to evaluate the capability of tiny lightweight polyimide spheres to reduce sound and vibration. The types of testing includes impedance tube measurement of propagation constant, sound power insertion loss for single and double wall systems, particle frame wave characterization and beam vibration reduction. The tests were performed using spheres made of two types of polyimide and with varying diameter. Baseline results were established using common noise reduction treatment materials such as fiberglass and foam. The spheres were difficult to test due to their inherent mobility. Most tests required some adaptation to contain the spheres. One test returned obvious non-linear behavior, a result which has come to be expected for treatments of this type. The polyimide spheres are found to be a competent treatment for both sound and vibration energy with the reservation that more work needs to be done to better characterize the non-linear behavior.
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Enhanced Sintering of TiNi Shape Memory Foams under Mg Vapor Atmosphere
NASA Astrophysics Data System (ADS)
Aydoğmuş, Tarik; Bor, Şakir
2012-12-01
TiNi alloy foams are promising candidates for biomaterials to be used as artificial orthopedic implant materials for bone replacement applications in biomedical sector. However, certain problems exist in their processing routes, such as formation of unwanted secondary intermetallic phases leading to brittleness and deterioration of shape memory and superelasticity characteristics; and the contamination during processing resulting in oxides and carbonitrides which affect mechanical properties negatively. Moreover, the eutectic reaction present in Ti-Ni binary system at 1391 K (1118 °C) prevents employment of higher sintering temperatures (and higher mechanical properties) even when equiatomic prealloyed powders are used because of Ni enrichment of TiNi matrix as a result of oxidation. It is essential to prevent oxidation of TiNi powders during processing for high-temperature (>1391 K i.e., 1118 °C) sintering practices. In the current study, magnesium powders were used as space holder material to produce TiNi foams with the porosities in the range of 40 to 65 pct. It has been found that magnesium prevents secondary phase formation and contamination. It also prevents liquid phase formation while enabling employment of higher sintering temperatures by two-step sintering processing: holding the sample at 1373 K (1100 °C) for 30 minutes, and subsequently sintering at temperatures higher than the eutectic temperature, 1391 K (1118 °C). By this procedure, magnesium may allow sintering up to temperatures close to the melting point of TiNi. TiNi foams produced with porosities in the range of 40 to 55 pct were found to be acceptable as implant materials in the light of their favorable mechanical properties.
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A nano universal joint made from curved double-walled carbon nanotubes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cai, Kun; Cai, Haifang; Shi, Jiao
2015-06-15
A nano universal joint is constructed from curved double-wall carbon nanotubes with a short outer tube as stator and a long inner tube as a rotor. When one end of the rotor is driven (by a rotary motor) to rotate, the same rotational speed but with different rotational direction will be induced at the other end of the rotor. This mechanism makes the joint useful for designing a flexible nanodevice with an adjustable output rotational signal. The motion transmission effect of the universal joint is analyzed using a molecular dynamics simulation approach. In particular, the effects of three factors aremore » investigated. The first factor is the curvature of the stator, which produces a different rotational direction of the rotor at the output end. The second is the bonding conditions of carbon atoms on the adjacent tube ends of the motor and the rotor, sp{sup 1} or sp{sup 2} atoms, which create different attraction between the motor and the rotor. The third is the rotational speed of the motor, which can be considered as the input signal of the universal joint. It is noted that the rotor's rotational speed is usually the same as that of the motor when the carbon atoms on the adjacent ends of the motor and the rotor are sp{sup 1} carbon atoms. When they become the new sp{sup 2} atoms, the rotor experiences a jump in rotational speed from a lower value to that of the motor. The mechanism of drops in potential of the motor is revealed. If the carbon atoms on the adjacent ends are sp{sup 2} atoms, the rotor rotates more slowly than the motor, whereas the rotational speed is stable when driven by a higher speed motor.« less
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A nano universal joint made from curved double-walled carbon nanotubes
NASA Astrophysics Data System (ADS)
Cai, Kun; Cai, Haifang; Shi, Jiao; Qin, Qing H.
2015-06-01
A nano universal joint is constructed from curved double-wall carbon nanotubes with a short outer tube as stator and a long inner tube as a rotor. When one end of the rotor is driven (by a rotary motor) to rotate, the same rotational speed but with different rotational direction will be induced at the other end of the rotor. This mechanism makes the joint useful for designing a flexible nanodevice with an adjustable output rotational signal. The motion transmission effect of the universal joint is analyzed using a molecular dynamics simulation approach. In particular, the effects of three factors are investigated. The first factor is the curvature of the stator, which produces a different rotational direction of the rotor at the output end. The second is the bonding conditions of carbon atoms on the adjacent tube ends of the motor and the rotor, sp1 or sp2 atoms, which create different attraction between the motor and the rotor. The third is the rotational speed of the motor, which can be considered as the input signal of the universal joint. It is noted that the rotor's rotational speed is usually the same as that of the motor when the carbon atoms on the adjacent ends of the motor and the rotor are sp1 carbon atoms. When they become the new sp2 atoms, the rotor experiences a jump in rotational speed from a lower value to that of the motor. The mechanism of drops in potential of the motor is revealed. If the carbon atoms on the adjacent ends are sp2 atoms, the rotor rotates more slowly than the motor, whereas the rotational speed is stable when driven by a higher speed motor.
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Effect of Alignment on Transport Properties of Carbon Nanotube/Metallic Junctions
NASA Technical Reports Server (NTRS)
Wincheski, Buzz; Namkung, Min; Smits, Jan; Williams, Phillip; Harvey, Robert
2003-01-01
Ballistic and spin coherent transport in single walled carbon nanotubes (SWCNT) are predicted to enable high sensitivity single-nanotube devices for strain and magnetic field sensing. Based upon these phenomena, electron beam lithography procedures have been developed to study the transport properties of purified HiPCO single walled carbon nanotubes for development into sensory materials for nondestructive evaluation. Purified nanotubes are dispersed in solvent suspension and then deposited on the device substrate before metallic contacts are defined and deposited through electron beam lithography. This procedure produces randomly dispersed ropes, typically 2 - 20 nm in diameter, of single walled carbon nanotubes. Transport and scanning probe microscopy studies have shown a good correlation between the junction resistance and tube density, alignment, and contact quality. In order to improve transport properties of the junctions a technique has been developed to align and concentrate nanotubes at specific locations on the substrate surface. Lithographic techniques are used to define local areas where high frequency electric fields are to be concentrated. Application of the fields while the substrate is exposed to nanotube-containing solution results in nanotube arrays aligned with the electric field lines. A second electron beam lithography layer is then used to deposit metallic contacts across the aligned tubes. Experimental measurements are presented showing the increased tube alignment and improvement in the transport properties of the junctions.
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Carbon Nano Tube Composites with Chemically Functionalized Plant Oils
NASA Astrophysics Data System (ADS)
Thielemans, Wim; Wool, Richard P.; Blau, Werner; Barron, Valerie
2003-03-01
Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality on the TG imparted amphiphilic properties to the oils which allows them to self-assemble on the nanotubes, promoting both dissolution and the ability to make nanocomposites with unusual properties. Once in solution, the MWCT can be processed in a variety of methods, in particular to make composites with enhanced mechanical, fracture and thermal properties. Since the tensile modulus of MWs is about 1 TPa and a vector percolation analysis indicated tensile strengths of 50-100 GPa, we obtain significantly improved properties with even small amounts (1-3the glass transition temperature of the composite by about 20 oC, and the tensile modulus by about 11significant effects on the fracture stress can be obtained due to the both the influence of the strength and length of the MWNT at the crack tip. The ability of the oils to self-assemble on the carbon nanotube surfaces also makes them ideal candidates for self-healing materials. The properties with different functionalized oils will be reported. Supported by EPA, DoE and ISF
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Micromirror structure actuated by TiNi shape memory thin films
NASA Astrophysics Data System (ADS)
Fu, Y. Q.; Luo, J. K.; Hu, M.; Du, H. J.; Flewitt, A. J.; Milne, W. I.
2005-10-01
TiNi films were deposited by co-sputtering TiNi and Ti targets. Results from differential scanning calorimetry and curvature measurement revealed martensitic transformation and shape memory effect upon heating and cooling. Two types of TiNi/Si micromirror structures with a Si mirror cap (40 µm thick) and TiNi/Si actuation beams were designed and fabricated. For the first design, a V-shaped cantilever based on the TiNi/Si bimorph structure was used as the actuation mechanism for the micromirror. In the second design, three elbow-shaped Si beams with TiNi electrodes were used as the arms to actuate the mirror. The TiNi/Si microbeams were flat at room temperature and bent up by applying voltage in the TiNi electrodes (due to phase transformation and shape memory effect), thus causing changes in angles of the micromirror.
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Method of coating graphite tubes with refractory metal carbides
Wohlberg, C.
1973-12-11
A method of coating graphite tubes with a refractory metal carbide is described. An alkali halide is reacted with a metallic oxide, the metallic portion being selected from the IVth or Vth group of the Periodic Table, the resulting salt reacting in turn with the carbon to give the desired refractory metal carbide coating. (Official Gazette)
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40 CFR Table 1b to Subpart Dddd of... - Add-on Control Systems Compliance Options
Code of Federal Regulations, 2010 CFR
2010-07-01
... Options For each of the following process units . . . You must comply with one of the following six...); pressurized refiners; primary tube dryers; secondary tube dryers; reconstituted wood product board coolers (at... are greater than or equal to 10 ppmvd. a You may choose to subtract methane from THC as carbon...
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The purpose of this SOP is to describe the procedures followed in the preparation of carbon-based multisorbent tubes for the collection of volatile organic compounds (VOCs) in air using actively-pumped samplers. This procedure was followed to ensure consistent data retrieval duri...
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Interactions of anions and cations in carbon nanotubes.
Mohammadzadeh, L; Quaino, P; Schmickler, W
2016-12-12
We consider the insertion of alkali-halide ion pairs into a narrow (5,5) carbon nanotube. In all cases considered, the insertion of a dimer is only slightly exothermic. While the image charge induced on the surface of the tube favors insertion, it simultaneously weakens the Coulomb attraction between the two ions. In addition, the anion experiences a sizable Pauli repulsion. For a one dimensional chain of NaCl embedded in the tube the most favorable position for the anion is at the center, and for the cation near the wall. The phonon spectrum of such chains shows both an acoustic and an optical branch.
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Controlled growth of well-aligned carbon nanotubes with large diameters
NASA Astrophysics Data System (ADS)
Wang, Xianbao; Liu, Yunqi; Zhu, Daoben
2001-06-01
Well-aligned carbon nanotubes (CNTs) with large diameters (25-200 nm) were synthesized by pyrolysis of iron(II) phthalocyanine. The outer diameter up to 218.5 nm and the length of the well-aligned CNTs can be systematically controlled by varying the growth time. A tube-in-tube nano-structure with large and small diameters of 176 and 16.7 nm, respectively, was found. The grain sizes of the iron catalyst play an important role in controlling the CNT diameters. These results are of great importance to design new aligned CNT-based electron field emitters in the potential application of panel displays.
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Li, Qi; Song, Ranran; Shi, Hui; Ma, Jianli; Liu, Xuehao; Li, Xiaochun
2018-04-01
The CO 2 injected into deep formations during implementation of carbon dioxide (CO 2 ) capture and storage (CCS) technology may leak and migrate into shallow aquifers or ground surfaces through a variety of pathways over a long period. The leaked CO 2 can threaten shallow environments as well as human health. Therefore, almost all monitoring programs for CCS projects around the world contain near-surface monitoring. This paper presents a U-tube based near-surface monitoring technology focusing on its first application in the Shenhua CCS demonstration project, located in the Ordos Basin, Inner Mongolia, China. First, background information on the site monitoring program of the Shenhua CCS demonstration project was provided. Then, the principle of fluid sampling and the monitoring methods were summarized for the U-tube sampler system, and the monitoring data were analyzed in detail. The U-tube based monitoring results showed that the U-tube sampler system is accurate, flexible, and representative of the subsurface fluid sampling process. The monitoring indicators for the subsurface water and soil gas at the Shenhua CCS site indicate good stratification characteristics. The concentration level of each monitoring indicator decreases with increasing depth. Finally, the significance of this near-surface environmental monitoring technology for CO 2 leakage assessments was preliminarily confirmed at the Shenhua CCS site. The application potential of the U-tube based monitoring technology was also demonstrated during the subsurface environmental monitoring of other CCS projects.
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Evaporation heat transfer of carbon dioxide at low temperature inside a horizontal smooth tube
NASA Astrophysics Data System (ADS)
Yoon, Jung-In; Son, Chang-Hyo; Jung, Suk-Ho; Jeon, Min-Ju; Yang, Dong-Il
2017-05-01
In this paper, the evaporation heat transfer coefficient of carbon dioxide at low temperature of -30 to -20 °C in a horizontal smooth tube was investigated experimentally. The test devices consist of mass flowmeter, pre-heater, magnetic gear pump, test section (evaporator), condenser and liquid receiver. Test section is made of cooper tube. Inner and outer diameter of the test section is 8 and 9.52 mm, respectively. The experiment is conducted at mass fluxes from 100 to 300 kg/m2 s, saturation temperature from -30 to -20 °C. The main results are summarized as follows: In case that the mass flux of carbon dioxide is 100 kg/m2 s, the evaporation heat transfer coefficient is almost constant regardless of vapor quality. In case of 200 and 300 kg/m2 s, the evaporation heat transfer coefficient increases steadily with increasing vapor quality. For the same mass flux, the evaporation heat transfer coefficient increases as the evaporation temperature of the refrigerant decreases. In comparison of heat transfer correlations with the experimental result, the evaporation heat transfer correlations do not predict them exactly. Therefore, more accurate heat transfer correlation than the previous one is required.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-04-12
... countervailing duty order on seamless carbon and alloy steel standard, line, and pressure pipe from the People's... administrative review of the countervailing duty order on seamless carbon and alloy steel standard, line, and... Making Co., Ltd., Wuxi Seamless Special Pipe Co., Ltd., Wuxi Sifang Steel Tube Co., Ltd., Wuxi Zhenda...
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NASA Technical Reports Server (NTRS)
Mutchler, W H; Buzzard, R W
1930-01-01
The survey of the possibilities for distinguishing between plain carbon and chromium-molybdenum steel tubing included the Herbert pendulum hardness, magnetic, sparks, and chemical tests. The Herbert pendulum test has the disadvantages of all hardness tests in being limited to factory use and being applicable only to scale-free, normalized material. The small difference in the range of hardness values between plain carbon and chromium-molybdenum steels is likewise a disadvantage. The Rockwell hardness test, at present used in the industry for this purpose, is much more reliable. It may be concluded on the basis of the experiments performed that of all methods surveyed, spark testing appears to be, at present, the most suitable for factory use from the standpoint of speed, accuracy, nondestructiveness and reliability. It is also applicable for field use.
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Hydraulic studies of drilling microbores with supercritical steam, nitrogen and carbon dioxide
Ken Oglesby
2010-01-01
Hydraulic studies of drilling microbores at various depths and with various hole sizes, tubing, fluids and rates showed theoretical feasibility. WELLFLO SIMULATIONS REPORT STEP 4: DRILLING 10,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE STEP 5: DRILLING 20,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE STEP 6: DRILLING 30,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE Mehmet Karaaslan, MSI
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Park, Jaehong; Reid, Obadiah G.; Blackburn, Jeffrey L.
The strong quantum confinement and low dielectric screening impart single-walled carbon nanotubes with exciton-binding energies substantially exceeding kBT at room temperature. Despite these large binding energies, reported photoluminescence quantum yields are typically low and some studies suggest that photoexcitation of carbon nanotube excitonic transitions can produce free charge carriers. Here we report the direct measurement of long-lived free-carrier generation in chirality-pure, single-walled carbon nanotubes in a low dielectric solvent. Time-resolved microwave conductivity enables contactless and quantitative measurement of the real and imaginary photoconductance of individually suspended nanotubes. We found that the conditions of the microwave conductivity measurement allow us tomore » avoid the complications of most previous measurements of nanotube free-carrier generation, including tube–tube/tube–electrode contact, dielectric screening by nearby excitons and many-body interactions. At low photon fluence (approximately 0.05 excitons per μm length of tubes), we directly observe free carriers on excitation of the first and second carbon nanotube exciton transitions.« less
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Structural analysis of an off-grid tiny house
NASA Astrophysics Data System (ADS)
Calluari, Karina Arias; Alonso-Marroquín, Fernando
2017-06-01
The off-grid technologies and tiny house movement have experimented an unprecedented growth in recent years. Putting both sides together, we are trying to achieve an economic and environmental friendly solution to the higher cost of residential properties. This solution is the construction of off-grid tiny houses. This article presents a design for a small modular off-grid house made by pine timber. A numerical analysis of the proposed tiny house was performed to ensure its structural stability. The results were compared with the suggested serviceability limit state criteria, which are contended in the Australia Guidelines Standards making this design reliable for construction.
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NASA Astrophysics Data System (ADS)
Blank, J. G.
2015-12-01
I am interested in looking for strange places where we might find life. Not life like you and me, but tiny life, smaller than our eyes can see. Sometimes, this tiny life leaves marks on rocks or in water that is living there now or that it once lived there long ago. This can be very interesting - it means that we might be able to know that some kind of life lived long ago even if it's not living now. It might also mean that we can find marks of life far far away from our home, on other worlds. One day people will go to other worlds to look for life. We hope to find it or marks that it was once there. I am going to talk about two places I study. In one, rocks are forming in plain daylight, in water that is only as deep as your knee (or maybe less). They should not be there. It seems very possible that the tiny life helps them form there. I study these rocks and ways that tiny life might help the rocks form. Rocks usually last a lot longer than tiny life, so they are an example of a mark that could last for a long long time and be a sign that life was once around there, long after the tiny life died. I will also talk about tiny life that lives under ground in the dark in places big enough that you and I can walk to. By this I mean that there is a trail that leads under ground with enough space for people to enter and study. Of course, we need light to see there, so we bring man made light with us. This tiny life gets food to live from water and rock, not from the sun. The tiny life also makes new rocks, usually easy to see because they are different colors from the other rocks. Again, this is a mark of life, and I am interested in how the marks from tiny life are made, how long they might last, and how many different kinds of marks I can find.
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Entropy of single-file water in (6,6) carbon nanotubes.
Waghe, Aparna; Rasaiah, Jayendran C; Hummer, Gerhard
2012-07-28
We used molecular dynamics simulations to investigate the thermodynamics of filling of a (6,6) open carbon nanotube (diameter D = 0.806 nm) solvated in TIP3P water over a temperature range from 280 K to 320 K at atmospheric pressure. In simulations of tubes with slightly weakened carbon-water attractive interactions, we observed multiple filling and emptying events. From the water occupancy statistics, we directly obtained the free energy of filling, and from its temperature dependence the entropy of filling. We found a negative entropy of about -1.3 k(B) per molecule for filling the nanotube with a hydrogen-bonded single-file chain of water molecules. The entropy of filling is nearly independent of the strength of the attractive carbon-water interactions over the range studied. In contrast, the energy of transfer depends strongly on the carbon-water attraction strength. These results are in good agreement with entropies of about -0.5 k(B) per water molecule obtained from grand-canonical Monte Carlo calculations of water in quasi-infinite tubes in vacuum under periodic boundary conditions. Overall, for realistic carbon-water interactions we expect that at ambient conditions filling of a (6,6) carbon nanotube open to a water reservoir is driven by a favorable decrease in energy, and opposed by a small loss of water entropy.
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Method of synthesizing small-diameter carbon nanotubes with electron field emission properties
NASA Technical Reports Server (NTRS)
Liu, Jie (Inventor); Du, Chunsheng (Inventor); Qian, Cheng (Inventor); Gao, Bo (Inventor); Qiu, Qi (Inventor); Zhou, Otto Z. (Inventor)
2009-01-01
Carbon nanotube material having an outer diameter less than 10 nm and a number of walls less than ten are disclosed. Also disclosed are an electron field emission device including a substrate, an optionally layer of adhesion-promoting layer, and a layer of electron field emission material. The electron field emission material includes a carbon nanotube having a number of concentric graphene shells per tube of from two to ten, an outer diameter from 2 to 8 nm, and a nanotube length greater than 0.1 microns. One method to fabricate carbon nanotubes includes the steps of (a) producing a catalyst containing Fe and Mo supported on MgO powder, (b) using a mixture of hydrogen and carbon containing gas as precursors, and (c) heating the catalyst to a temperature above 950.degree. C. to produce a carbon nanotube. Another method of fabricating an electron field emission cathode includes the steps of (a) synthesizing electron field emission materials containing carbon nanotubes with a number of concentric graphene shells per tube from two to ten, an outer diameter of from 2 to 8 nm, and a length greater than 0.1 microns, (b) dispersing the electron field emission material in a suitable solvent, (c) depositing the electron field emission materials onto a substrate, and (d) annealing the substrate.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Joseph Berkmans, A.; Jagannatham, M.; Priyanka, S.
Highlights: • Polymer wastes are converted into ultrafine and nano carbon tubes and spheres. • Simple process with a minimal processing time. • It is a catalyst free and solvent free approach. • This process forms branched ultrafine carbon tubules with nano channels. - Abstract: Upcycling polymer wastes into useful, and valuable carbon based materials, is a challenging process. We report a novel catalyst-free and solvent-free technique for the formation of nano channeled ultrafine carbon tubes (NCUFCTs) and multiwalled carbon nanotubes (MWCNTs) from polyethylene terephthalate (PET) wastes, using rotating cathode arc discharge technique. The soot obtain from the anode containsmore » ultrafine and nano-sized solid carbon spheres (SCS) with a mean diameter of 221 nm and 100 nm, respectively, formed at the lower temperature region of the anode where the temperature is approximately 1700 °C. The carbon spheres are converted into long “Y” type branched and non-branched NCUFCTs and MWCNTs at higher temperature regions where the temperature is approximately 2600 °C, with mean diameters of 364 nm and 95 nm, respectively. Soot deposited on the cathode is composed of MWCNTs with a mean diameter of 20 nm and other nanoparticles. The tubular structures present in the anode are longer, bent and often coiled with lesser graphitization compared to the nanotubes in the soot on the cathode.« less
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Electrical property of macroscopic graphene composite fibers prepared by chemical vapor deposition
NASA Astrophysics Data System (ADS)
Sun, Haibin; Fu, Can; Gao, Yanli; Guo, Pengfei; Wang, Chunlei; Yang, Wenchao; Wang, Qishang; Zhang, Chongwu; Wang, Junya; Xu, Junqi
2018-07-01
Graphene fibers are promising candidates in portable and wearable electronics due to their tiny volume, flexibility and wearability. Here, we successfully synthesized macroscopic graphene composite fibers via a two-step process, i.e. first electrospinning and then chemical vapor deposition (CVD). Briefly, the well-dispersed PAN nanofibers were sprayed onto the copper surface in an electrified thin liquid jet by electrospinning. Subsequently, CVD growth process induced the formation of graphene films using a PAN-solid source of carbon and a copper catalyst. Finally, crumpled and macroscopic graphene composite fibers were obtained from carbon nanofiber/graphene composite webs by self-assembly process in the deionized water. Temperature-dependent conduct behavior reveals that electron transport of the graphene composite fibers belongs to hopping mechanism and the typical electrical conductivity reaches 4.59 × 103 S m‑1. These results demonstrated that the graphene composite fibers are promising for the next-generation flexible and wearable electronics.
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Ultrashort Carbon Nanotubes That Fluoresce Brightly in the Near-Infrared.
Danné, Noémie; Kim, Mijin; Godin, Antoine G; Kwon, Hyejin; Gao, Zhenghong; Wu, Xiaojian; Hartmann, Nicolai F; Doorn, Stephen K; Lounis, Brahim; Wang, YuHuang; Cognet, Laurent
2018-06-14
The intrinsic near-infrared photoluminescence observed in long single-walled carbon nanotubes is known to be quenched in ultrashort nanotubes due to their tiny size as compared to the exciton diffusion length in these materials (>100 nm). Here, we show that intense photoluminescence can be created in ultrashort nanotubes (∼40 nm length) upon incorporation of exciton-trapping sp 3 defect sites. Using super-resolution photoluminescence imaging at <25 nm resolution, we directly show the preferential localization of excitons at the nanotube ends, which separate by less than 40 nm and behave as independent emitters. This unexpected observation opens the possibility to synthesize fluorescent ultrashort nanotubes-a goal that has been long thought impossible-for bioimaging applications, where bright near-infrared photoluminescence and small size are highly desirable, and for quantum information science, where high quality and well-controlled near-infrared single photon emitters are needed.
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Modeling of Electronic Transport in Scanning Tunneling Microscope Tip-Carbon Nanotube Systems
NASA Technical Reports Server (NTRS)
Yamada, Toshishige; Kwak, Dochan (Technical Monitor)
2000-01-01
A model is proposed for two observed current-voltage (I-V) patterns in a recent experiment with a scanning tunneling microscope tip and a carbon nanotube. We claim that there are two mechanical contact modes for a tip (metal) -nanotube (semiconductor) junction (1) with or (2) without a tiny vacuum gap (0.1 - 0.2 nm). With the tip grounded, the tunneling case in (1) would produce large dI/dV with V > 0, small dI/dV with V < 0, and I = 0 near V = 0 for an either n- or p-nanotube; the Schottky mechanism in (2) would result in I does not equal 0 only with V < 0 for an n-nanotube, and the bias polarities would be reversed for a p-nanotube. The two observed I-V patterns are thus entirely explained by a tip-nanotube contact of the two types, where the nanotube must be n-type.
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A Green Synthesis of Carbon Nanoparticle from Honey for Real-Time Photoacoustic Imaging.
Wu, Lina; Cai, Xin; Nelson, Kate; Xing, Wenxin; Xia, Jun; Zhang, Ruiying; Stacy, Allen J; Luderer, Micah; Lanza, Gregory M; Wang, Lihong V; Shen, Baozhong; Pan, Dipanjan
2013-01-01
Imaging sentinel lymph nodes (SLN) could provide us with critical information about the progression of a cancerous disease. Real-time high-resolution intraoperative photoacoustic imaging (PAI) in conjunction with a near infrared (NIR) probe may offer the opportunities for the immediate imaging for direct identification and resection of SLN or collecting tissue samples. In this work a commercially amenable synthetic methodology is revealed for developing luminescent carbon nanoparticles with rapid clearance properties. A one-pot "green" technique is pursued, which involved rapid surface passivation of carbon nanoparticles with organic macromolecules (e.g. polysorbate, polyethyleneglycol) in a solvent free condition. Interestingly, the naked carbon nanoparticles are derived for the first time, from commercial food grade honey. Surface coated particles are markedly smaller (~7 nm) than the previously explored particles (gold, SWNT, copper) for SLN imaging. Results indicate an exceptionally rapid signal enhancement (~2 min) of the SLN. Owing to their strong optical absorption in the near infrared region, tiny size and rapid lymphatic transport, this platform offers great potential for faster resection of SLN and may lower complications caused by axillary investigation for mismarking with dyes or low-resolution imaging techniques.
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Evaluating the electrical discharge machining (EDM) parameters with using carbon nanotubes
NASA Astrophysics Data System (ADS)
Sari, M. M.; Noordin, M. Y.; Brusa, E.
2012-09-01
Electrical discharge machining (EDM) is one of the most accurate non traditional manufacturing processes available for creating tiny apertures, complex or simple shapes and geometries within parts and assemblies. Performance of the EDM process is usually evaluated in terms of surface roughness, existence of cracks, voids and recast layer on the surface of product, after machining. Unfortunately, the high heat generated on the electrically discharged material during the EDM process decreases the quality of products. Carbon nanotubes display unexpected strength and unique electrical and thermal properties. Multi-wall carbon nanotubes are therefore on purpose added to the dielectric used in the EDM process to improve its performance when machining the AISI H13 tool steel, by means of copper electrodes. Some EDM parameters such as material removal rate, electrode wear rate, surface roughness and recast layer are here first evaluated, then compared to the outcome of EDM performed without using nanotubes mixed to the dielectric. Independent variables investigated are pulse on time, peak current and interval time. Experimental evidences show that EDM process operated by mixing multi-wall carbon nanotubes within the dielectric looks more efficient, particularly if machining parameters are set at low pulse of energy.
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Biswal, Mandakini; Deshpande, Aparna; Kelkar, Sarika; Ogale, Satishchandra
2014-03-01
A conducting carbon cloth, which has an interesting turbostratic microstructure and functional groups that are distinctly different from other ordered forms of carbon, such as graphite, graphene, and carbon nanotubes, was synthesized by a simple one-step pyrolysis of cellulose fabric. This turbostratic disorder and surface chemical functionalities had interesting consequences for water splitting and hydrogen generation when such a cloth was used as an electrode in the alkaline electrolysis process. Importantly, this work also gives a new twist to carbon-assisted electrolysis. During electrolysis, the active sites in the carbon cloth allow slow oxidation of its surface to transform the surface groups from COH to COOH and so forth at a voltage as low as 0.2 V in a two-electrode system, along with platinum as the cathode, instead of 1.23 V (plus overpotential), which is required for platinum, steel, or even graphite anodes. The quantity of subthreshold hydrogen evolved was 24 mL cm(-2) h(-1) at 1 V. Interestingly, at a superthreshold potential (>1.23 V+overpotential), another remarkable phenomenon was found. At such voltages, along with the high rate and quantity of hydrogen evolution, rapid exfoliation of the tiny nanoscale (5-7 nm) units of carbon quantum dots (CQDs) are found in copious amounts due to an enhanced oxidation rate. These CQDs show bright-blue fluorescence under UV light. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing
2018-01-01
In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9% and nitrogen (N) doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g−1, it still delivers a high discharge capacity of 329 mA h g−1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes. PMID:29686985
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Role of structural defects in the ultraviolet luminescence of multiwall boron nitride nanotubes
DOE Office of Scientific and Technical Information (OSTI.GOV)
Pierret, Aurélie; Nong, Hanond; Fossard, Frédéric
2015-12-21
BN nanotubes (BNNTs) are structurally similar to their carbon counterparts, though much less investigated. New synthesis methods have been recently reported, enabling the production of industrial quantities and stimulating the search of new applications for the BNNTs. In this paper, we investigate the luminescence of multiwall BNNTs. By performing cathodoluminescence experiments on single tubes at 10 K, we show that the tube luminescence is highly heterogeneous (i) from tube to tube and (ii) spatially along a single tube. By combining cathodoluminescence measurements with a nanometer excitation and transmission electron microscopy on the same tube, we correlate luminescence and structural features. Wemore » conclude that the near-band-edge luminescence of BNNTs (≈5.4 eV) is related to the presence of extended structural defects, such as dislocations or ruptures in the wall stacking.« less
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Solar concentrator with integrated tracking and light delivery system with summation
Maxey, Lonnie Curt
2015-05-05
A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector redirects the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and provides light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting that uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.
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Solar concentrator with integrated tracking and light delivery system with collimation
Maxey, Lonnie Curt
2015-06-09
A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector directs the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and distributes light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting, uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.
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High temperature ceramic-tubed reformer
NASA Astrophysics Data System (ADS)
Williams, Joseph J.; Rosenberg, Robert A.; McDonough, Lane J.
1990-03-01
The overall objective of the HiPHES project is to develop an advanced high-pressure heat exchanger for a convective steam/methane reformer. The HiPHES steam/methane reformer is a convective, shell and tube type, catalytic reactor. The use of ceramic tubes will allow reaction temperature higher than the current state-of-the-art outlet temperatures of about 1600 F using metal tubes. Higher reaction temperatures increase feedstock conversion to synthesis gas and reduce energy requirements compared to currently available radiant-box type reformers using metal tubes. Reforming of natural gas is the principal method used to produce synthesis gas (primarily hydrogen and carbon monoxide, H2 and CO) which is used to produce hydrogen (for refinery upgrading), methanol, as well as several other important materials. The HiPHES reformer development is an extension of Stone and Webster's efforts to develop a metal-tubed convective reformer integrated with a gas turbine cycle.
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Environmental Detection of Single-Walled Carbon Nanotubes Utilizing Near-Infrared Fluorescence
There are a growing number of applications for carbon nanotubes (CNT) in modern technologies and, subsequently, growth in production of CNT has expanded rapidly. Single-walled CNT (SWCNT) consist of a graphene sheet rolled up into a tube. With growing manufacture and use, the ...
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Chan, Vera Bin San; Li, Chaoyi; Lane, Ackley Charles; Wang, Yanchun; Lu, Xingwen; Shih, Kaimin; Zhang, Tong; Thiyagarajan, Vengatesen
2012-01-01
As a consequence of anthropogenic CO2-driven ocean acidification (OA), coastal waters are becoming increasingly challenging for calcifiers due to reductions in saturation states of calcium carbonate (CaCO3) minerals. The response of calcification rate is one of the most frequently investigated symptoms of OA. However, OA may also result in poor quality calcareous products through impaired calcification processes despite there being no observed change in calcification rate. The mineralogy and ultrastructure of the calcareous products under OA conditions may be altered, resulting in changes to the mechanical properties of calcified structures. Here, the warm water biofouling tubeworm, Hydroides elegans, was reared from larva to early juvenile stage at the aragonite saturation state (ΩA) for the current pCO2 level (ambient) and those predicted for the years 2050, 2100 and 2300. Composition, ultrastructure and mechanical strength of the calcareous tubes produced by those early juvenile tubeworms were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nanoindentation. Juvenile tubes were composed primarily of the highly soluble CaCO3 mineral form, aragonite. Tubes produced in seawater with aragonite saturation states near or below one had significantly higher proportions of the crystalline precursor, amorphous calcium carbonate (ACC) and the calcite/aragonite ratio dramatically increased. These alterations in tube mineralogy resulted in a holistic deterioration of the tube hardness and elasticity. Thus, in conditions where ΩA is near or below one, the aragonite-producing juvenile tubeworms may no longer be able to maintain the integrity of their calcification products, and may result in reduced survivorship due to the weakened tube protection. PMID:22912726
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-04-19
... tubing, of iron (other than cast iron) or steel (both carbon and alloy), whether seamless or welded... Seamless Tube Mill of Inner Mongolia Baotou Steel 29.94 and Trading Co., Ltd Union Co., Ltd.\\27\\ Benxi... Century Machinery Co. Ltd.;Tianjin Seamless Steel Pipe Plant; Baoshan Iron & Steel Co. Ltd Shengli...
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Kumar, Sunil; Pattanayek, Sudip K; Pereira, Gerald G
2014-01-14
We use molecular dynamics simulations to investigate the arrangement of polymer chains when absorbed onto a long, single-wall carbon nano-tube (SWCNT). We study the conformation and organization of the polymer chains on the SWCNT and their dependence on the tube's diameter and the rate of cooling. We use two types of cooling processes: direct quenching and gradual cooling. The radial density distribution function and bond orientational order parameter are used to characterize the polymer chain structure near the surface. In the direct cooling process, the beads of the polymer chain organize in lamella-like patterns on the surface of the SWCNT with the long axis of the lamella parallel to the axis of the SWCNT. In a stepwise, gradual cooling process, the polymer beads form a helical pattern on the surface of a relatively thick SWCNT, but form a lamella-like pattern on the surface of a very thin SWCNT. We develop a theoretical (free energy) model to explain this difference in pattern structures for the gradual cooling process and also provide a qualitative explanation for the pattern that forms from the direct cooling process.
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Guo, Chunmei; Chen, Yi; Chen, Jinfu; Wang, Xiaojun; Zhang, Guangqing; Wang, Jingxiu; Cui, Wenfeng; Zhang, Zhongzhi
2014-10-01
This paper investigated the enhancement of the COD reduction of an oilfield wastewater treatment process by installing air-lift tubes and adding an activated carbon bioreactor (ACB) to form a combined hydrolysis acidification and bio-contact oxidation system with air-lift tubes (HA/air-lift BCO) and an ACB. Three heat-resistant bacterial strains were cultivated and subsequently applied in above pilot plant test. Installing air-lift tubes in aerobic tanks reduced the necessary air to water ratio from 20 to 5. Continuous operation of the HA/air-lift BCO system for 2 months with a hydraulic retention time of 36 h, a volumetric load of 0.14 kg COD/(m(3)d) (hydrolysis-acidification or anaerobic tank), and 0.06 kg COD/(m(3)d) (aerobic tanks) achieved an average reduction of COD by 60%, oil and grease by 62%, total suspended solids by 75%, and sulfides by 77%. With a COD load of 0.56 kg/(m(3)d), the average COD in the ACB effluent was 58 mg/L. Copyright © 2014 Elsevier Ltd. All rights reserved.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Colburn, W.A.; Vane, F.M.; Bugge, C.J.
The pharmacokinetics of isotretinoin and 4-oxoisotretinoin in blood, as well as the blood concentrations and urinary, biliary, and fecal excretion of carbon-14 were studied using liquid scintillation counting techniques and reverse phase HPLC methods following a single 80-mg oral suspension dose of UC-isotretinoin to four healthy male subjects and two patients with biliary T-tube drainage. Approximately 80% of the dose was recovered as UC in excreta during the course of the study of which about equal fractions were in the urine and feces. Secondary peaks in blood concentrations of UC were observed in the healthy subjects whereas they were notmore » seen in the patients with T-tubes. The harmonic mean apparent half-life for isotretinoin in the blood of the healthy subjects was 13.6 hr, whereas the corresponding value for the UC was 90 hr. The data for isotretinoin and 4-oxoisotretinoin coupled with the total carbon-14 data suggest that the oral dose of UC-isotretinoin is absorbed to a similar extent by the healthy subjects and T-tube patients, whereas T-tube patients clear the drug more rapidly. The biliary excretion and possible enterohepatic circulation of isotretinoin and its metabolites may have significant impact on the pharmacokinetic profile of isotretinoin in man.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Neises, T. W.; Wagner, M. J.; Gray, A. K.
Research of advanced power cycles has shown supercritical carbon dioxide power cycles may have thermal efficiency benefits relative to steam cycles at temperatures around 500 - 700 degrees C. To realize these benefits for CSP, it is necessary to increase the maximum outlet temperature of current tower designs. Research at NREL is investigating a concept that uses high-pressure supercritical carbon dioxide as the heat transfer fluid to achieve a 650 degrees C receiver outlet temperature. At these operating conditions, creep becomes an important factor in the design of a tubular receiver and contemporary design assumptions for both solar and traditionalmore » boiler applications must be revisited and revised. This paper discusses lessons learned for high-pressure, high-temperature tubular receiver design. An analysis of a simplified receiver tube is discussed, and the results show the limiting stress mechanisms in the tube and the impact on the maximum allowable flux as design parameters vary. Results of this preliminary analysis indicate an underlying trade-off between tube thickness and the maximum allowable flux on the tube. Future work will expand the scope of design variables considered and attempt to optimize the design based on cost and performance metrics.« less
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NASA Astrophysics Data System (ADS)
Lee, H. W.; Lim, H. W.; Jeon, D. H.; Park, C. K.; Cho, H. S.; Seo, C. W.; Lee, D. Y.; Kim, K. S.; Kim, G. A.; Park, S. Y.; Kang, S. Y.; Park, J. E.; Kim, W. S.; Woo, T. H.; Oh, J. E.
2018-06-01
This study investigated the effectiveness of a new method for measuring the actual focal spot position of a diagnostic x-ray tube using a high-precision antiscatter grid and a digital x-ray detector in which grid magnification, which is directly related to the focal spot position, was determined from the Fourier spectrum of the acquired x-ray grid’s image. A systematic experiment was performed to demonstrate the viability of the proposed measurement method. The hardware system used in the experiment consisted of an x-ray tube run at 50 kVp and 1 mA, a flat-panel detector with a pixel size of 49.5 µm, and a high-precision carbon-interspaced grid with a strip density of 200 lines/inch. The results indicated that the focal spot of the x-ray tube (Jupiter 5000, Oxford Instruments) used in the experiment was located approximately 31.10 mm inside from the exit flange, well agreed with the nominal value of 31.05 mm, which demonstrates the viability of the proposed measurement method. Thus, the proposed method can be utilized for system’s performance optimization in many x-ray imaging applications.
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Multi-Scale Simulations of Carbon Nanotubes: Mechanics and Electronics
NASA Technical Reports Server (NTRS)
Srivastava, Deepak
2003-01-01
Carbon Nanotube (CNT) is a tubular form of carbon with diameter as small as 1 nm. Length: few mn to microns. CNT is configurationally equivalent to a two dimensional graphene sheet rolled into a tube. CNT exhibits extraordinary mechanical properties; Young's modulus over 1 Tera Pascal, as stiff as diamond, and tensile strength approx. 200 GPa. CNT can be metallic or semiconducting, depending on chirality.
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Modified Activated Carbon Perchlorate Sorbents
2007-01-25
Yield 4.64 g. Methyl Chloride Alkylated Activated Carbon Methyl chloride (MeCl) treatment was carried out in a tube furnace generally in...with alkylation agents lowers the solution pH as the basic sites are alkylated . In the case of Me2SO4 treatment , the low slurry pH is believed to be...by Cannon and coworkers, the alkylated carbons are not significantly better. In the case of the SAI carbons, ammonia treatment does not result in a
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Simulations of fill tube effects on the implosion of high-foot NIF ignition capsules
NASA Astrophysics Data System (ADS)
Dittrich, T. R.; Hurricane, O. A.; Berzak-Hopkins, L. F.; Callahan, D. A.; Casey, D. T.; Clark, D.; Dewald, E. L.; Doeppner, T.; Haan, S. W.; Hammel, B. A.; Harte, J. A.; Hinkel, D. E.; Kozioziemski, B. J.; Kritcher, A. L.; Ma, T.; Nikroo, A.; Pak, A. E.; Parham, T. G.; Park, H.-S.; Patel, P. K.; Remington, B. A.; Salmonson, J. D.; Springer, P. T.; Weber, C. R.; Zimmerman, G. B.; Kline, J. L.
2016-05-01
Encouraging results have been obtained using a strong first shock during the implosion of carbon-based ablator ignition capsules. These “high-foot” implosion results show that capsule performance deviates from 1D expectations as laser power and energy are increased. A possible cause of this deviation is the disruption of the hot spot by jets originating in the capsule fill tube. Nominally, a 10 μm outside diameter glass (SiO2) fill tube is used in these implosions. Simulations indicate that a thin coating of Au on this glass tube may lessen the hotspot disruption. These results and other mitigation strategies will be presented.
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Effect of flame-tube head structure on combustion chamber performance
NASA Technical Reports Server (NTRS)
Gu, Minqqi
1986-01-01
The experimental combustion performance of a premixed, pilot-type flame tube with various head structures is discussed. The test study covers an extensive area: efficiency of the combustion chamber, quality of the outlet temperature field, limit of the fuel-lean blowout, ignition performance at ground starting, and carbon deposition. As a result of these tests, a nozzle was found which fits the premixed pilot flame tube well. The use of this nozzle optimized the performance of the combustion chamber. The tested models had premixed pilot chambers with two types of air-film-cooling structures, six types of venturi-tube structures, and secondary fuel nozzles with two small spray-cone angles.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Dawson, Elizabeth A.; Parkes, Gareth M. B.; Bond, Gary
This article describes a system to investigate the parameters for the remediation of organic vapors using microwave-induced plasma on fluidized carbon granules. The system is based on a single mode microwave apparatus with a variable power (2.45 GHz) generator. Carbon granules are fluidized in a silica tube situated in the sample section of a waveguide incorporating two additional ports to allow plasma intensity monitoring using a light sensor and imaging with a digital camera. A fluoroptic probe is used for in situ measurement of the carbon granule temperature, while the effluent gas temperature is measured with a thermocouple situated inmore » the silica tube outside the cavity. Data acquisition and control software allow experiments using a variety of microwave power regimes while simultaneously recording the light intensity of any plasma generated within the carbon bed, together with its temperature. Evaluation using two different granular activated carbons and ethyl acetate, introduced as a vapor into the fluidizing air stream at a concentration of 1 ppm, yielded results which indicated that significant destruction of ethyl acetate, as monitored using a mass spectrometer, was achieved only with the carbon granules showing high plasma activity under pulsed microwave conditions. The system is therefore suitable for comparison of the relative microwave activities of various activated carbon granules and their performance in microwave remediation and regeneration.« less
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Tang, Jialiang; Pol, Vilas G.
2016-01-01
The conversion of allergic pollen grains into carbon microstructures was carried out through a facile, one-step, solid-state pyrolysis process in an inert atmosphere. The as-prepared carbonaceous particles were further air activated at 300 °C and then evaluated as lithium ion battery anodes at room (25 °C) and elevated (50 °C) temperatures. The distinct morphologies of bee pollens and cattail pollens are resembled on the final architecture of produced carbons. Scanning Electron Microscopy images shows that activated bee pollen carbon (ABP) is comprised of spiky, brain-like, and tiny spheres; while activated cattail pollen carbon (ACP) resembles deflated spheres. Structural analysis through X-ray diffraction and Raman spectroscopy confirmed their amorphous nature. X-ray photoelectron spectroscopy analysis of ABP and ACP confirmed that both samples contain high levels of oxygen and small amount of nitrogen contents. At C/10 rate, ACP electrode delivered high specific lithium storage reversible capacities (590 mAh/g at 50 °C and 382 mAh/g at 25 °C) and also exhibited excellent high rate capabilities. Through electrochemical impedance spectroscopy studies, improved performance of ACP is attributed to its lower charge transfer resistance than ABP. Current studies demonstrate that morphologically distinct renewable pollens could produce carbon architectures for anode applications in energy storage devices. PMID:26846311
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NASA Astrophysics Data System (ADS)
Tang, Jialiang; Pol, Vilas G.
2016-02-01
The conversion of allergic pollen grains into carbon microstructures was carried out through a facile, one-step, solid-state pyrolysis process in an inert atmosphere. The as-prepared carbonaceous particles were further air activated at 300 °C and then evaluated as lithium ion battery anodes at room (25 °C) and elevated (50 °C) temperatures. The distinct morphologies of bee pollens and cattail pollens are resembled on the final architecture of produced carbons. Scanning Electron Microscopy images shows that activated bee pollen carbon (ABP) is comprised of spiky, brain-like, and tiny spheres; while activated cattail pollen carbon (ACP) resembles deflated spheres. Structural analysis through X-ray diffraction and Raman spectroscopy confirmed their amorphous nature. X-ray photoelectron spectroscopy analysis of ABP and ACP confirmed that both samples contain high levels of oxygen and small amount of nitrogen contents. At C/10 rate, ACP electrode delivered high specific lithium storage reversible capacities (590 mAh/g at 50 °C and 382 mAh/g at 25 °C) and also exhibited excellent high rate capabilities. Through electrochemical impedance spectroscopy studies, improved performance of ACP is attributed to its lower charge transfer resistance than ABP. Current studies demonstrate that morphologically distinct renewable pollens could produce carbon architectures for anode applications in energy storage devices.
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Tang, Jialiang; Etacheri, Vinodkumar; Pol, Vilas G
2016-02-05
The conversion of allergic pollen grains into carbon microstructures was carried out through a facile, one-step, solid-state pyrolysis process in an inert atmosphere. The as-prepared carbonaceous particles were further air activated at 300 °C and then evaluated as lithium ion battery anodes at room (25 °C) and elevated (50 °C) temperatures. The distinct morphologies of bee pollens and cattail pollens are resembled on the final architecture of produced carbons. Scanning Electron Microscopy images shows that activated bee pollen carbon (ABP) is comprised of spiky, brain-like, and tiny spheres; while activated cattail pollen carbon (ACP) resembles deflated spheres. Structural analysis through X-ray diffraction and Raman spectroscopy confirmed their amorphous nature. X-ray photoelectron spectroscopy analysis of ABP and ACP confirmed that both samples contain high levels of oxygen and small amount of nitrogen contents. At C/10 rate, ACP electrode delivered high specific lithium storage reversible capacities (590 mAh/g at 50 °C and 382 mAh/g at 25 °C) and also exhibited excellent high rate capabilities. Through electrochemical impedance spectroscopy studies, improved performance of ACP is attributed to its lower charge transfer resistance than ABP. Current studies demonstrate that morphologically distinct renewable pollens could produce carbon architectures for anode applications in energy storage devices.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Bradley, J.M.
The feasibility of building a freeze-tolerant absorber for a solar water heater out of carbon-black-reinforced crosslinked polyethylene has been explored. Ten-foot tube specimens made from various crosslinked polyethylene formulations were filled with water at various pressures, and then placed into a deep freeze, then thawed and frozen again for 100 freeze-thaw cycles, or until the tube specimen failed. Tube diameters were measured before and after each freezing to determine how much distention the freezing caused, and how much permanent distention was caused by the strains of repeated freezings. Five tube specimens containing water at as high as 80 psi survivedmore » 100 freeze-thaw cycles. Also, a flat plate collector was fabricated using as absorber surface a single 400 ft tube of carbon-black-reinforced crosslinked polyethylene in the form of a flat spiral coil and this collector was tested for performance at the Los Alamos Scientific Laboratory. The performance test indicates that the absorbancy of such a flat spiral coil to solar radiation is similar to typical black surfaces used on solar absorbers. Thus, it does seem very feasible that domestic water can be directly heated in a solar collector having an absorber made from crosslinked polyethylene, and that this collector can safely withstand at least 100 freeze-thaw cycles.« less
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Deposit formation and heat transfer in hydrocarbon rocket fuels
NASA Technical Reports Server (NTRS)
Giovanetti, A. J.; Spadaccini, L. J.; Szetela, E. J.
1983-01-01
An experimental research program was undertaken to investigate the thermal stability and heat transfer characteristics of several hydrocarbon fuels under conditions that simulate high-pressure, rocket engine cooling systems. The rates of carbon deposition in heated copper and nickel-plated copper tubes were determined for RP-1, propane, and natural gas using a continuous flow test apparatus which permitted independent variation and evaluation of the effect on deposit formation of wall temperature, fuel pressure, and fuel velocity. In addition, the effects of fuel additives and contaminants, cryogenic fuel temperatures, and extended duration testing with intermittent operation were examined. Parametric tests to map the thermal stability characteristics of RP-1, commercial-grade propane, and natural gas were conducted at pressures of 6.9 to 13.8 MPa, bulk fuel velocities of 30 to 90 m/s, and tube wall temperatures in the range of 230 to 810 K. Also, tests were run in which propane and natural gas fuels were chilled to 230 and 160 K, respectively. Corrosion of the copper tube surface was detected for all fuels tested. Plating the inside of the copper tubes with nickel reduced deposit formation and eliminated tube corrosion in most cases. The lowest rates of carbon deposition were obtained for natural gas, and the highest rates were obtained for propane. For all fuels tested, the forced-convection heat transfer film coefficients were satisfactorily correlated using a Nusselt-Reynolds-Prandtl number equation.
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Vibrational energy transfer between carbon nanotubes and liquid water: a molecular dynamics study.
Nelson, Tammie R; Chaban, Vitaly V; Kalugin, Oleg N; Prezhdo, Oleg V
2010-04-08
The rates and magnitudes of vibrational energy transfer between single-wall carbon nanotubes (CNTs) and water are investigated by classical molecular dynamics. The interactions between the CNT and solvent confined inside of the tube, the CNT and solvent surrounding the tube, as well as the solvent inside and outside of the tube are considered for the (11,11), (15,15), and (19,19) armchair CNTs. The vibrational energy transfer exhibits two time scales, subpicosecond and picosecond, of roughly equal importance. Solvent molecules confined within CNTs are more strongly coupled to the tubes than the outside molecules. The energy exchange is facilitated by slow collective motions, including CNT radial breathing modes (RBM). The transfer rate between CNTs and the inside solvent shows strong dependence on the CNT diameter. In smaller tubes, the transfer is faster and the solvent coupling to RBMs is stronger. The magnitude of the CNT-outside solvent interaction scales with the CNT surface area, while that of the CNT-inside solvent exhibits scaling that is intermediate between the CNT volume and surface. The Coulomb interaction between the solvent molecules inside and outside of the CNTs is much weaker than the CNT-solvent interactions. The results indicate that the excitation energy supplied to CNTs in chemical and biological applications is rapidly deposited to the active molecular agents and should remain localized sufficiently long in order to perform the desired function.
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Parham, Walter E.
1969-01-01
Weathering products formed on surfaces of both potassium and plagioclase feldspar (An70), which were continuously leached in a Soxhlet extraction apparatus for 140 days with 7.21 of distilled water per day at a temperature of approximately 78°C, are morphologically identical to natural products developed on potassium feldspars weathered under conditions of good drainage in the humid tropics. The new products, which first appear as tiny bumps on the feldspar surface, start to develop mainly at exposed edges but also at apparently random sites on flat cleavage surfaces. As weathering continues, the bumps grow outward from the feldspar surface to form tapered projections, which then develop into wide-based thin films or sheets. The thin sheets of many projections merge laterally to form one continuous flame-shaped sheet. The sheets formed on potassium feldspars may then roll to form tubes that are inclined at a high angle to the feldspar surface. Etch pits of triangular outline on the artificially weathered potassium feldspars serve as sites for development of continuous, non-rolled, hollow tubes. It is inferred from its morphology that this weathering product is halloysite or its primitive form. The product of naturally weathered potassium feldspars is halloysite . 4H2O.The flame-shaped films or sheets formed on artificially weathered plagioclase feldspar do not develop into hollow tubes, but instead give rise to a platy mineral that is most probably boehmite. These plates form within the flame-shaped films, and with continued weathering are released as the film deteriorates. There is no indication from this experiment that platy pseudohexagonal kaolinite forms from any of these minerals under the initial stage of weathering.
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Regenerable metallic oxide systems for removal of carbon dioxide: A concept
NASA Technical Reports Server (NTRS)
Sutton, J. G.; Heimlich, P. F.; Tepper, E. H.
1972-01-01
Design concepts for portable canisters for removal of carbon dioxide are described. One is screen pack configuration consisting of brazed rectangular canister with four metal oxide packs inserted. Other is radial flow canister with perforated central tube. Methods of production and operating principles are presented.
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Bent Bonds and Multiple Bonds.
ERIC Educational Resources Information Center
Robinson, Edward A.; Gillespie, Ronald J.
1980-01-01
Considers carbon-carbon multiple bonds in terms of Pauling's bent bond model, which allows direct calculation of double and triple bonds from the length of a CC single bond. Lengths of these multiple bonds are estimated from direct measurements on "bent-bond" models constructed of plastic tubing and standard kits. (CS)
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Evaluation of Length-of-Stain Gas Indicator Tubes for Measuring Carbon Monoxide in Air
DOT National Transportation Integrated Search
1971-11-01
Techniques for detection and measurement of carbon monoxide (CO) in air are of interest and utility in many aspects of automotive safety. CO concentrations may range from less than 100 parts per million (ppm), or 0.01 percent, to about 10 percent by ...
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Federal Register 2010, 2011, 2012, 2013, 2014
2010-11-05
... Lloyds Metals & Engineers Ltd. and Lloyds Steel Industries Ltd.) (collectively, Lloyds) and Ushdev... and all affiliates, Lloyds Metals & Engineers Ltd., and Lloyds Steel Industries Ltd. Because we... DEPARTMENT OF COMMERCE International Trade Administration [A-533-502] Certain Welded Carbon Steel...
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Molecular Dynamics Simulations of the Thermal Conductivity of Single-Wall Carbon Nanotubes
NASA Technical Reports Server (NTRS)
Osman, M.; Srivastava, Deepak; Govindan,T. R. (Technical Monitor)
2000-01-01
Carbon nanotubes (CNT) have very attractive electronic, mechanical. and thermal properties. Recently, measurements of thermal conductivity in single wall CNT mats showed estimated thermal conductivity magnitudes ranging from 17.5 to 58 W/cm-K at room temperature. which are better than bulk graphite. The cylinderical symmetry of CNT leads to large thermal conductivity along the tube axis, additionally, unlike graphite. CNTs can be made into ropes that can be used as heat conducting pipes for nanoscale applications. The thermal conductivity of several single wall carbon nanotubes has been calculated over temperature range from l00 K to 600 K using non-equilibrium molecular dynamics using Tersoff-Brenner potential for C-C interactions. Thermal conductivity of single wall CNTs shows a peaking behavior as a function of temperature. Dependence of the peak position on the chirality and radius of the tube will be discussed and explained in this presentation.
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NASA Technical Reports Server (NTRS)
Masters, P. A.; Aukerman, C. A.
1982-01-01
A high pressure fuel coking testing apparatus was designed and developed and was used to evaluate thermal decomposition limits and carbon decomposition rates in heated copper tubes for hydrocarbon fuels. A commercial propane (90% grade) and chemically pure (CP) propane were tested. Heat transfer to supercritical propane was evaluated at 136 atm, bulk fluid velocities of 6 to 30 m/s, and tube wall temperatures in the range of 422 to 811 K. A forced convection heat transfer correlation developed in a previous test effort verified a prediction of most of the experimental data within a + or - 30% range, with good agreement for the CP propane data. No significant differences were apparent in the predictions derived from the correlation when the carbon resistance was included with the film resistance. A post-test scanning electron microprobe analysis indicated occurrences of migration and interdiffusion of copper into the carbon deposit.
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NASA Astrophysics Data System (ADS)
Ueda, Kengo; Kuwahara, Kiyoshi; Fujiyama, Hiroshi
1999-07-01
Soot containing fullerenes, such as C60 and C70, was synthesized with He plasmas generated in a quartz tube by microwave-glow discharge. A reticulated vitreous carbon (RVC) heated by the microwave He plasmas with an electric field of TE10 mode was used as the carbon source. Swan bands of C2 molecules were observed during the synthesis by optical emission spectroscopy (OES) in order to investigate the effect of the vibrational temperature of C2 molecules on the formation of the fullerenes. The soot deposited on the quartz tube was analyzed by laser desorption time-of-flight mass-spectroscopy (LD-TOF-MS). The intensities of the mass spectra of fullerenes were confirmed to be maximum for the conditions as follows: the absorbed microwave power Pab=200 W and the He gas pressure P=100 Torr, while the C2 vibrational temperature was approximately 7000 K.
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Carbon nanotubes synthesized by Ni-assisted atmospheric pressure thermal chemical vapor deposition
NASA Astrophysics Data System (ADS)
Choi, G. S.; Cho, Y. S.; Hong, S. Y.; Park, J. B.; Son, K. H.; Kim, D. J.
2002-03-01
A detailed systematic study on the growth morphology of carbon nanotubes (CNTs) on Si in atmospheric pressure thermal chemical vapor deposition was undertaken. The role of NH3 for vertical alignment of CNTs was investigated. The direct cause for the alignment was a dense distribution of the catalytic metal particles, but that the particles are maintained catalytically active under amorphous carbon deposits was established by NH3. It allows a dense nucleation of the CNTs, and consequently, assists vertical alignment through entanglement and mechanical leaning among the tubes. The CNTs grew in a base growth mode. Since Ni is consumed both by silicide reaction and by capture into the growing tube, the growth stops when Ni is totally depleted. It occurs earlier for smaller particles, and thus a long time of growth results in a thin bottom with poor adhesion.
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Liger-Belair, Gérard
2005-04-20
In this review, the latest results about the chemical physics behind the bubbling properties of Champagne and sparkling wines are collected and fully illustrated. The chemistry of carbon dioxide molecules dissolved into the liquid matrix (section 2) is presented, as are the three main steps of a fleeting bubble's life, that is, the bubble nucleation on tiny particles stuck on the glass wall (section 3), the bubble ascent and growth through the liquid matrix (section 4), and the bursting of bubbles at the liquid surface (section 5), which constitutes the most intriguing, functional, and visually appealing step.
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Carbon nanotubes for thermal interface materials in microelectronic packaging
NASA Astrophysics Data System (ADS)
Lin, Wei
As the integration scale of transistors/devices in a chip/system keeps increasing, effective cooling has become more and more important in microelectronics. To address the thermal dissipation issue, one important solution is to develop thermal interface materials with higher performance. Carbon nanotubes, given their high intrinsic thermal and mechanical properties, and their high thermal and chemical stabilities, have received extensive attention from both academia and industry as a candidate for high-performance thermal interface materials. The thesis is devoted to addressing some challenges related to the potential application of carbon nanotubes as thermal interface materials in microelectronics. These challenges include: 1) controlled synthesis of vertically aligned carbon nanotubes on various bulk substrates via chemical vapor deposition and the fundamental understanding involved; 2) development of a scalable annealing process to improve the intrinsic properties of synthesized carbon nanotubes; 3) development of a state-of-art assembling process to effectively implement high-quality vertically aligned carbon nanotubes into a flip-chip assembly; 4) a reliable thermal measurement of intrinsic thermal transport property of vertically aligned carbon nanotube films; 5) improvement of interfacial thermal transport between carbon nanotubes and other materials. The major achievements are summarized. 1. Based on the fundamental understanding of catalytic chemical vapor deposition processes and the growth mechanism of carbon nanotube, fast synthesis of high-quality vertically aligned carbon nanotubes on various bulk substrates (e.g., copper, quartz, silicon, aluminum oxide, etc.) has been successfully achieved. The synthesis of vertically aligned carbon nanotubes on the bulk copper substrate by the thermal chemical vapor deposition process has set a world record. In order to functionalize the synthesized carbon nanotubes while maintaining their good vertical alignment, an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon. 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ˜35% and ˜65%, respectively, in tensile strength (˜0.8 GPa) and modulus (˜90 GPa) during tensile testing; an ˜20% improvement in electrical conductivity (˜80000 S m-1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such a microwave annealing process has been extended to the preparation of reduced graphene oxide. 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding. 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ˜30 mm2 s-1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ˜27 and ˜540 W m-1 K-1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing density was beneficial in increasing the collective thermal conductivity of the VACNT film; however, the increased tube-tube interaction in dense VACNT films decreased the thermal conductivity of the individual CNTs. The tip-to-tip contact resistance was shown to be ˜1x10-7 m2 K W -1. The study will shed light on the potential application of VACNTs as thermal interface materials in microelectronic packaging. 5. A combined process of in situ functionalization and microwave curing has been developed to effective enhance the interface between carbon nanotubes and the epoxy matrix. Effective medium theory has been used to analyze the interfacial thermal resistance between carbon nanotubes and polymer matrix, and that between graphite nanoplatlets and polymer matrix.
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A theoretical study for mechanical contact between carbon nanotubes
NASA Astrophysics Data System (ADS)
Takagi, Yoshiteru; Uda, Tsuyoshi; Ohno, Takahisa
2005-03-01
We have theoretically investigated motions of single-walled carbon nanotubes (SWNTs) which are mounted on a flat substrate layer of SWNTs by tight-binding molecular dynamics simulations. One of the most interesting motions is the conversion of force and torque, where the force and torque acting initially on the mounted tube finally results in the lateral motion and rolling of the supporting tubes in the substrate. This motion is well understood in terms of the total energy surface of the SWNT/SWNT system. It is suggested that an undulation of the total energy surface plays a role as an atomic-scale gear tooth in the field of nanomechanics, in spite of the atomically smooth surface of SWNT.
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Prediction of radial breathing-like modes of double-walled carbon nanotubes with arbitrary chirality
NASA Astrophysics Data System (ADS)
Ghavanloo, Esmaeal; Fazelzadeh, S. Ahmad
2014-10-01
The radial breathing-like modes (RBLMs) of double-walled carbon nanotubes (DWCNTs) with arbitrary chirality are investigated by a simple analytical model. For this purpose, DWCNT is considered as double concentric elastic thin cylindrical shells, which are coupled through van der Waals (vdW) forces between two adjacent tubes. Lennard-Jones potential and a molecular mechanics model are used to calculate the vdW forces and to predict the mechanical properties, respectively. The validity of these theoretical results is confirmed through the comparison of the experimental results. Finally, a new approach is proposed to determine the diameters and the chiral indices of the inner and outer tubes of the DWCNTs with high precision.
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Buckyball Nucleation of HiPco Tubes
NASA Technical Reports Server (NTRS)
Smalley, Richard E.
2012-01-01
The purpose of this innovation is to enhance nucleation of single-wall nanotubes (SWNTs) in the HiPco process, selectively producing 10,10 tubes, something which until now has not been thought possible. This is accomplished by injecting C60, or a derivative of C60, solubilized in supercritical CO2 together with a transition metal carboneal cocatalyst into the HiPco reactor. This is a variant on the supercritical disclosure. C60 has never been used to nucleate carbon nanotubes in the gas phase. C60 itself may not have adequate solubility in supercritical CO2. However, fluorinated C60, e.g., C60F36, is easy to make cheaply and should have much enhanced solubility.
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Lucek, R W; Dickerson, J; Carter, D E; Bugge, C J; Crews, T; Vane, F M; Cunningham, W; Colburn, W A
1988-01-01
The pharmacokinetic profile of 14C-etretinate, a retinoid that is effective in the treatment of psoriasis, was studied in six healthy male volunteers and two biliary T-tube patients. Following a 100 mg oral dose of 14C-etretinate (20 microcurie), etretinate and its major blood metabolites (etretin, isoetretin) were measured by HPLC and total carbon-14 was measured in blood, bile, urine, and feces by liquid scintillation counting. Etretinate was extensively metabolized in healthy volunteers and in T-tube patients. During the absorption phase, 75 per cent of the total radioactivity in the blood could be accounted for as etretinate, etretin, and isoetretin whereas these compounds accounted for only approximately 12 per cent of the blood radioactivity in T-tube patients over the same time period. The blood concentrations of etretinate, etretin, and isoetretin appeared to be substantially reduced in T-tube patients compared to those in healthy volunteers. A higher proportion of the total drug was excreted in the feces and bile of the T-tube patients (84 per cent) than in the feces of healthy volunteers (62 per cent). The major factor responsible for the observed decrease in etretinate blood concentrations following biliary cannulation appears to be the reduced absorption of etretinate due to the elimination of solubilizing bile salts in the duodenum. Carbon-14 related material was detected in urine and feces for as long as 3 weeks in healthy subjects supporting the previous observation that a long terminal elimination half-life exists for etretinate, even following a single dose of the compound.
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Health Hazard Evaluation Report HETA 84-513-1572, Hawaii News Agency, Honolulu, Hawaii
DOE Office of Scientific and Technical Information (OSTI.GOV)
Okawa, M.T.
1985-04-01
On September 5, 1984, the National Institute for Occupational Safety and Health (NIOSH) received a request from an authorized representative of employees from the Hawaii Newspaper Agency (HNA), Honolulu, Hawaii, to conduct a health-hazard evaluation of the indoor air quality in the HNA Building. The requestor was concerned about the incidence of colds, flu, and sore throats which seemed to linger among employees in the Star-Bulletin side of the Building. On October 17, 1984, the NIOSH investigator visited the Building in order to obtain information on the ventilation system, to pass out a short questionnaire concerning possible workplace related symptoms,more » and to take detector tube readings for carbon dioxide (CO/sub 2/). On October 18, 1984, the NIOSH investigator repeated CO/sub 2/ samples and also took detector tube readings for carbon monoxide (CO). The detector tube measurements for CO/sub 2/ and CO were used as a screening device to assess the general air circulation in the office spaces.« less
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Al-zubaidi, Ayar; Ishii, Yosuke; Yamada, Saki; Matsushita, Tomohiro; Kawasaki, Shinji
2013-12-21
We investigated the changes in charge carrier density responsible for the dumbbell-like cyclic voltammogram of single-walled carbon nanotubes (SWCNTs) used as electric double layer capacitor electrodes. We utilized in situ Raman spectroscopy of SWCNTs in the potential range where the dumbbell voltammogram is observed and electric double layer charging would be the dominant mechanism. The study revealed that, unexpectedly, the spectroscopic changes coinciding with the dumbbell steps on the voltammogram occur more sharply in metallic tubes, as seen from (1) the sudden enhancement in the intensity of the BWF Breit-Wigner-Fano (BWF) feature, (2) a considerably more significant frequency upshift of G(+) and G' bands, and (3) a drop in radial breathing mode intensity, compared to those in the spectra of semiconducting tubes. In addition, the spectroscopic changes observed with open-end SWCNT samples were more defined and correlated more accurately with the electronic structure of the tubes compared to those observed with closed-end SWCNTs.
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NASA Astrophysics Data System (ADS)
Shulga, A. V.
2017-12-01
This article presents the results of comparative studies of mechanical properties and microstructure of nuclear fuel tubes and semifinished stainless steel items fabricated by consolidation of rapidly quenched powders and by conventional technology after high-temperature exposures at 600 and 700°C. Tensile tests of nuclear fuel tube ring specimens of stainless austenitic steel of grade AISI 316 and ferritic-martensitic steel are performed at room temperature. The microstructure and distribution of carbon and boron are analyzed by metallography and autoradiography in nuclear fuel tubes and semifinished items. Rapidly quenched powders of the considered steels are obtained by the plasma rotating electrode process. Positive influence of consolidation of rapidly quenched powders on mechanical properties after high-temperature aging is confirmed. The correlation between homogeneous distribution of carbon and boron and mechanical properties of the considered steel is determined. The effects of thermal aging and degradation of the considered steels are determined at 600°C and 700°C, respectively.
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Sulfur-impregnated disordered carbon nanotubes cathode for lithium-sulfur batteries.
Guo, Juchen; Xu, Yunhua; Wang, Chunsheng
2011-10-12
The commercialization of lithium-sulfur batteries is hindered by low cycle stability and low efficiency, which are induced by sulfur active material loss and polysulfide shuttle reaction through dissolution into electrolyte. In this study, sulfur-impregnated disordered carbon nanotubes are synthesized as cathode material for the lithium-sulfur battery. The obtained sulfur-carbon tube cathodes demonstrate superior cyclability and Coulombic efficiency. More importantly, the electrochemical characterization indicates a new stabilization mechanism of sulfur in carbon induced by heat treatment.
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Contamination risk of stable isotope samples during milling.
Isaac-Renton, M; Schneider, L; Treydte, K
2016-07-15
Isotope analysis of wood is an important tool in dendrochronology and ecophysiology. Prior to mass spectrometry analysis, wood must be homogenized, and a convenient method involves a ball mill capable of milling samples directly in sample tubes. However, sample-tube plastic can contaminate wood during milling, which could lead to biological misinterpretations. We tested possible contamination of whole wood and cellulose samples during ball-mill homogenization for carbon and oxygen isotope measurements. We used a multi-factorial design with two/three steel milling balls, two sample amounts (10 mg, 40 mg), and two milling times (5 min, 10 min). We further analyzed abrasion by milling empty tubes, and measured the isotope ratios of pure contaminants. A strong risk exists for carbon isotope bias through plastic contamination: the δ(13) C value of polypropylene deviated from the control by -6.77‰. Small fibers from PTFE filter bags used during cellulose extraction also present a risk as the δ(13) C value of this plastic deviated by -5.02‰. Low sample amounts (10 mg) showed highest contamination due to increased abrasion during milling (-1.34‰), which is further concentrated by cellulose extraction (-3.38‰). Oxygen isotope measurements were unaffected. A ball mill can be used to homogenize samples within test tubes prior to oxygen isotope analysis, but not prior to carbon or radiocarbon isotope analysis. There is still a need for a fast, simple and contamination-free sample preparation procedure. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.
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NASA Astrophysics Data System (ADS)
Mustonen, K.; Laiho, P.; Kaskela, A.; Zhu, Z.; Reynaud, O.; Houbenov, N.; Tian, Y.; Susi, T.; Jiang, H.; Nasibulin, A. G.; Kauppinen, E. I.
2015-07-01
We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3-4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ˜105 cm-3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.
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Biocide-mediated corrosion of coiled tubing.
Sharma, Mohita; An, Dongshan; Liu, Tao; Pinnock, Tijan; Cheng, Frank; Voordouw, Gerrit
2017-01-01
Coiled tubing corrosion was investigated for 16 field water samples (S5 to S20) from a Canadian shale gas field. Weight loss corrosion rates of carbon steel beads incubated with these field water samples averaged 0.2 mm/yr, but injection water sample S19 had 1.25±0.07 mm/yr. S19 had a most probable number of zero acid-producing bacteria and incubation of S19 with carbon steel beads or coupons did not lead to big changes in microbial community composition. In contrast other field water samples had most probable numbers of APB of 102/mL to 107/mL and incubation of these field water samples with carbon steel beads or coupons often gave large changes in microbial community composition. HPLC analysis indicated that all field water samples had elevated concentrations of bromide (average 1.6 mM), which may be derived from bronopol, which was used as a biocide. S19 had the highest bromide concentration (4.2 mM) and was the only water sample with a high concentration of active bronopol (13.8 mM, 2760 ppm). Corrosion rates increased linearly with bronopol concentration, as determined by weight loss of carbon steel beads, for experiments with S19, with filtered S19 and with bronopol dissolved in defined medium. This indicated that the high corrosion rate found for S19 was due to its high bronopol concentration. The corrosion rate of coiled tubing coupons also increased linearly with bronopol concentration as determined by electrochemical methods. Profilometry measurements also showed formation of multiple pits on the surface of coiled tubing coupon with an average pit depth of 60 μm after 1 week of incubation with 1 mM bronopol. At the recommended dosage of 100 ppm the corrosiveness of bronopol towards carbon steel beads was modest (0.011 mm/yr). Higher concentrations, resulting if biocide is added repeatedly as commonly done in shale gas operations, are more corrosive and should be avoided. Overdosing may be avoided by assaying the presence of residual biocide by HPLC, rather than by assaying the presence of residual surviving bacteria.
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Biocide-mediated corrosion of coiled tubing
An, Dongshan; Liu, Tao; Pinnock, Tijan; Cheng, Frank; Voordouw, Gerrit
2017-01-01
Coiled tubing corrosion was investigated for 16 field water samples (S5 to S20) from a Canadian shale gas field. Weight loss corrosion rates of carbon steel beads incubated with these field water samples averaged 0.2 mm/yr, but injection water sample S19 had 1.25±0.07 mm/yr. S19 had a most probable number of zero acid-producing bacteria and incubation of S19 with carbon steel beads or coupons did not lead to big changes in microbial community composition. In contrast other field water samples had most probable numbers of APB of 102/mL to 107/mL and incubation of these field water samples with carbon steel beads or coupons often gave large changes in microbial community composition. HPLC analysis indicated that all field water samples had elevated concentrations of bromide (average 1.6 mM), which may be derived from bronopol, which was used as a biocide. S19 had the highest bromide concentration (4.2 mM) and was the only water sample with a high concentration of active bronopol (13.8 mM, 2760 ppm). Corrosion rates increased linearly with bronopol concentration, as determined by weight loss of carbon steel beads, for experiments with S19, with filtered S19 and with bronopol dissolved in defined medium. This indicated that the high corrosion rate found for S19 was due to its high bronopol concentration. The corrosion rate of coiled tubing coupons also increased linearly with bronopol concentration as determined by electrochemical methods. Profilometry measurements also showed formation of multiple pits on the surface of coiled tubing coupon with an average pit depth of 60 μm after 1 week of incubation with 1 mM bronopol. At the recommended dosage of 100 ppm the corrosiveness of bronopol towards carbon steel beads was modest (0.011 mm/yr). Higher concentrations, resulting if biocide is added repeatedly as commonly done in shale gas operations, are more corrosive and should be avoided. Overdosing may be avoided by assaying the presence of residual biocide by HPLC, rather than by assaying the presence of residual surviving bacteria. PMID:28746397
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NASA Astrophysics Data System (ADS)
Guin, William Edward
Carbon nanotubes (CNTs) are ideal candidates for the reinforcement of the matrix and interphase zone in polymer matrix composites (PMCs), due to their ability to more effectively bind the reinforcing fibers to the matrix material. This can lead to the enhancement of several critical composite properties - including interfacial shear strength and interlaminar fracture toughness - that are typically associated with a composite material's resistance to delamination. Direct dispersion of CNTs into the matrix of the composites has been shown to be very difficult. A more effective way to reinforce PMCs using CNTs is to grow CNTs directly on the reinforcing fibers. To this end, a novel technique used to grow CNTs directly on carbon fibers has been developed at The University of Alabama and Auburn University. This method, referred to as the PopTube Approach, uses microwave irradiation to grow CNTs at room temperature in air, without the need for inert gas protection or additional feed stock gases. The simple nature of the PopTube Approach lends itself to large-scale, high-yield manufacturing that can be done in a cost effective manner. However, before this technique is developed beyond the laboratory scale, its effectiveness as a route to produce CNT-reinforced composites must be evaluated in a comprehensive manner. The objective of this work is to do just that - characterize the mechanical properties of CNT-reinforced composites produced via the PopTube Approach. A systematic experimental program is carried out to provide a comprehensive assessment of the effects of the PopTube Approach on a wide range of composite mechanical properties. Results show that the PopTube Approach provides for enhanced resistance to delamination with respect to several different loading events. Fractography studies are used to qualitatively understand the mechanisms responsible for these improvements in delamination resistance on the micro-scale. Results also suggest that improvements in delamination resistance via CNT reinforcement may come at the expense of the tensile properties of PMCs - which gives rise to the conclusion that in practice, the degree and manner of CNT reinforcement in PMCs should be carefully considered on an application-by-application basis. Together, the collection of studies performed herein provides a wide-ranging quantitative and qualitative assessment of the effects of the PopTube Approach CNT reinforcement scheme on the mechanical properties and behavior of polymer matrix composites.
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Rapid solar-thermal decarbonization of methane
NASA Astrophysics Data System (ADS)
Dahl, Jaimee Kristen
Due to the ever-increasing demand for energy and the concern over the environmental impact of continuing to produce energy using current methods, there is interest in developing a hydrogen economy. Hydrogen is a desirable energy source because it is abundant in nature and burns cleanly. One method for producing hydrogen is to utilize a renewable energy source to obtain high enough temperatures to decompose a fossil fuel into its elements. This thesis work is directed at developing a solar-thermal aerosol flow reactor to dissociate methane to carbon black and hydrogen. The technology is intended as a "bridge" between current hydrogen production methods, such as conventional steam-methane reformers, and future "zero emission" technology for producing hydrogen, such as dissociating water using a renewable heating source. A solar furnace is used to heat a reactor to temperatures in excess of 2000 K. The final reactor design studied consists of three concentric vertical tubes---an outer quartz protection tube, a middle solid graphite heating tube, and an inner porous graphite reaction tube. A "fluid-wall" is created on the inside wall of the porous reaction tube in order to prevent deposition of the carbon black co-product on the reactor tube wall. The amorphous carbon black produced aids in heating the gas stream by absorbing radiation from the reactor wall. Conversions of 90% are obtained at a reactor wall temperature of 2100 K and an average residence time of 0.01 s. Computer modeling is also performed to study the gas flow and temperature profiles in the reactor as well as the kinetics of the methane dissociation reaction. The simulations indicate that there is little flow of the fluid-wall gas through the porous wall in the hot zone region, but this can be remedied by increasing the inlet temperature of the fluid-wall gas and/or increasing the tube permeability only in the hot zone region of the wall. The following expression describes the kinetics of methane dissociation in a solar-thermal fluid-wall reactor: dXdt=5.8x108 exp-155,600RT 1-X 7.2s-1. The experimental and theoretical work reported in this thesis is the groundwork that will be utilized in scaling up the reactor to produce hydrogen in distributed or centralized facilities.
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Local Gate Control of a Carbon Nanotube Double Quantum Dot
2016-04-04
Nanotube Double Quantum Dot N. Mason,*† M. J. Biercuk,* C. M. Marcus† We have measured carbon nanotube quantum dots with multiple electro- static gates and...computation. Carbon nanotubes have been considered lead- ing candidates for nanoscale electronic applica- tions (1, 2). Previous measurements of nano- tube...electronics have shown electron confine- ment (quantum dot) effects such as single- electron charging and energy-level quantization (3–5). Nanotube
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PECVD Growth of Carbon Nanotubes
NASA Technical Reports Server (NTRS)
McAninch, Ian; Arnold, James O. (Technical Monitor)
2001-01-01
Plasma enhanced chemical vapor deposition (PECVD), using inductively coupled plasma, has been used to grow carbon nanotubes (CNTs) and graphitic carbon fibers (GCF) on substrates sputtered with aluminum and iron catalyst. The capacitive plasma's power has been shown to cause a transition from nanotubes to nanofibers, depending on the strength of the plasma. The temperature, placement, and other factors have been shown to affect the height and density of the tube and fiber growth.
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Evaluation of Fuzzy Fiber Sensors for Structural Health Monitoring
2010-11-01
detect damage. Should damage occur at other unanticipated regions, it may go undetected. Methods have been devised to use the sensors in a network...graphene tubes around the core of an SWCNT lead to multi-walled carbon nanotubes ( MWCNTs ). These CNTs have diameters in a range between one to tens...performance carbon-carbon composites, EMI shielding, lightning strike, energy storage, thermal management, bio-implants, and bone regeneration (pend- ing
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JPRS Report, Science & Technology, Europe
1992-02-18
could penetrate the ceramic layer. At the time, the Essen researchers were unable to present any proof of the obvious assumption that microfine pores...carbon fiber tubes and titanium frame joints that are very light and strong. The manufacturing system and experiments are installed as modules on...study also view the manufacturing technol- ogies and jointing techniques for active cooling with an integrated cooling tube system as unavailable—pure
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NASA Astrophysics Data System (ADS)
Yokoyama, Yusuke; Miyairi, Yousuke; Matsuzaki, Hiroyuki; Tsunomori, Fumiaki
2007-06-01
Availability of an effective graphitization system is essential for the successful operation of an AMS laboratory for radiocarbon measurements. We have set up a graphitization system consisting of metal vacuum lines for cleaning CO2 sample gas which is then converted to graphite. CO2 gas from a carbonate sample is produced in vacuum in a test tube by injecting concentrated phosphoric acid. The tube is placed into a heated metal block to accelerate dissolution. However, we have observed systematic differences in the time required to convert the CO2 gas to graphite under a hydrogen atmosphere, from less than 3 h to over 10 h. We have conducted a series of experiments including background measurements and yield measurements to monitor secondary carbon contamination and changes in isotopic fractionation. All of the tests show that the carbon isotope ratios remain unaffected by the duration of the process. We also used a quadrupole mass spectrometer (QMS) to identify possible contaminant gases. Contaminant peaks were identified at high mass (larger than 60) only for long duration experiments. This suggests a possible reaction between the rubber cap and acid fumes producing a contaminant gas that impeded the reduction of CO2.
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NASA Astrophysics Data System (ADS)
Shahzadi, Iqra; Nadeem, S.; Rabiei, Faranak
The current article deals with the combine effects of single wall carbon nanotubes and effective viscosity for the peristaltic flow of nanofluid through annulus. The nature of the walls is assumed to be permeable. The present theoretical model can be considered as mathematical representation to the motion of conductive physiological fluids in the existence of the endoscope tube which has many biomedical applications such as drug delivery system. The outer tube has a wave of sinusoidal nature that is travelling along its walls while the inner tube is rigid and uniform. Lubrication approach is used for the considered analysis. An empirical relation for the effective variable viscosity of nanofluid is proposed here interestingly. The viscosity of nanofluid is the function of radial distance and the concentration of nanoparticles. Exact solution for the resulting system of equations is displayed for various quantities of interest. The outcomes show that the maximum velocity of SWCNT-blood nanofluid enhances for larger values of viscosity parameter. The pressure gradient in the more extensive part of the annulus is likewise found to increase as a function of variable viscosity parameter. The size of the trapped bolus is also influenced by variable viscosity parameter. The present examination also revealed that the carbon nanotubes have many applications related to biomedicine.
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Flame Synthesis of Single- and Multi-Walled Carbon Nanotubes and Nanofibers
NASA Technical Reports Server (NTRS)
VanderWal, R. L.; Ticich, Thomas M.
2001-01-01
Metal-catalyzed carbon nanotubes are highly sought for a diverse range of applications that include nanoelectronics, battery electrode material, catalysis, hydrogen storage media and reinforcing agents in polymer composites. These latter applications will require vast quantities of nanotubes at competitive prices to be economically feasible. Moreover, reinforcing applications may not require ultrahigh purity nanotubes. Indeed, functionalization of nanotubes to facilitate interfacial bonding within composites will naturally introduce defects into the tube walls, lessening their tensile strength. Current methods of aerosol synthesis of carbon nanotubes include laser ablation of composite targets of carbon and catalyst metal within high temperature furnaces and decomposition of a organometallics in hydrocarbons mixtures within a tube furnace. Common to each approach is the generation of particles in the presence of the reactive hydrocarbon species at elevated temperatures. In the laser-ablation approach, the situation is even more dynamic in that particles and nanotubes are borne during the transient cooling phase of the laser-induced plasma for which the temperature far exceeds that of the surrounding hot gases within the furnace process tube. A shared limitation is that more efficient methods of nanoparticle synthesis are not readily incorporated into these approaches. In contrast, combustion can quite naturally create nanomaterials such as carbon black. Flame synthesis is well known for its commercial scalability and energy efficiency. However, flames do present a complex chemical environment with steep gradients in temperature and species concentrations. Moreover, reaction times are limited within buoyant driven flows to tens of milliseconds. Therein microgravity can greatly lessen temperature and spatial gradients while allowing independent control of flame residence times. In preparation for defining the microgravity experiments, the work presented here focuses on the effect of catalyst particle size and reactant gas in 1g.
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NASA Astrophysics Data System (ADS)
MacPhee, A. G.; Smalyuk, V. A.; Landen, O. L.; Weber, C. R.; Robey, H. F.; Alfonso, E. L.; Biener, J.; Bunn, T.; Crippen, J. W.; Farrell, M.; Felker, S.; Field, J. E.; Hsing, W. W.; Kong, C.; Milovich, J.; Moore, A.; Nikroo, A.; Rice, N.; Stadermann, M.; Wild, C.
2018-05-01
We report a reduced X-ray shadow imprint of hydrodynamic instabilities on the high-density carbon ablator surface of inertial confinement fusion (ICF) capsules using a reduced diameter fuel fill tube on the National Ignition Facility (NIF). The perturbation seed mass from hydrodynamic instabilities was reduced by approximately an order of magnitude by reducing both the diameter and wall thickness of the fill tube by ˜2×, consistent with analytical estimates. This work demonstrates a successful mitigation strategy for engineered features for ICF implosions on the NIF.
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Carbon Nanotube Switches for Communication and Memory Applications
NASA Technical Reports Server (NTRS)
Kaul, Anupama B.; Epp, Larry; Wong, Eric W.; Kowalczyk, Robert
2008-01-01
Lateral CNT Switches: a) dc CNT switches were demonstrated to operate at low voltages, low powers and high speeds. b) RF simulations of switch in series configuration with metallized tube yielded good RF performance 1) Isolation simulated to be approx. 20 dB at 100 GHz. 2) Insertion loss simulated to be < 0.5 dB at 100 GHz. Vertical CNT Switches: a) Thermal CVD was used to mechanically constrain tubes in nanopockets; tubes not self-supporting. b) Demonstrated growth of vertically aligned arrays and single-few MWNTs using dc PECVD with Ni catalyst using optical lithography.
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Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control
NASA Technical Reports Server (NTRS)
Hagopian, John; Getty, Stephanie; Quijada, Manuel
2012-01-01
Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced stray light control capability by making a blacker surface treatment for typical stray light control components. Since baffles, stops, and tubes used in scientific observations often undergo loads such as vibration, it was critical to develop this surface treatment on structural materials. The innovation is to optimize the carbon nanotube growth for titanium, which is a strong, lightweight structural material suitable for spaceflight use. The titanium substrate carbon nanotubes are more robust than those grown on silicon and allow for easier utilization. They are darker than current surface treatments over larger angles and larger wavelength range. The primary advantage of titanium substrate is that it is a good structural material, and not as brittle as silicon.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-12-09
... Zhongyuan Steel Pipe Manufacturer (``Hebei Zhongyuan''), Hefei Zijin Steel Tube Manufacturing Co., Ltd... Quality Steel Pipe From the People's Republic of China: Rescission of the 2010-2011 Antidumping Duty... antidumping duty order on circular welded carbon quality steel pipe (``CWP'') from the People's Republic of...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-15
...) Tension Steel Industries Co. Ltd. Partial Rescission The applicable regulation, 19 CFR 351.213(d)(1....); and (6) Tension Steel Industries Co. Ltd. This review will continue with respect to Yieh Phui... DEPARTMENT OF COMMERCE International Trade Administration [A-583-008] Circular Welded Carbon Steel...
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Chen, Ze; Ye, Sunjie; Evans, Stephen D; Ge, Yuanhang; Zhu, Zhifeng; Tu, Yingfeng; Yang, Xiaoming
2018-05-01
Carbonaceous nanotubes (CTs) represent one of the most popular and effective carbon electrode materials for supercapacitors, but the electrochemistry performance of CTs is largely limited by their relatively low specific surface area, insufficient usage of intratube cavity, low content of heteroatom, and poor porosity. An emerging strategy for circumventing these issues is to design novel porous CT-based nanostructures. Herein, a spheres-in-tube nanostructure with hierarchical porosity is successfully engineered, by encapsulating heteroatom-doping hollow carbon spheres into one carbonaceous nanotube (HCSs@CT). This intriguing nanoarchitecture integrates the merits of large specific surface area, good porosity, and high content of heteroatoms, which synergistically facilitates the transportation and exchange of ions and electrons. Accordingly, the as-prepared HCSs@CTs possess outstanding performances as electrode materials of supercapacitors, including superior capacitance to that of CTs, HCSs, and their mixtures, coupled with excellent cycling life, demonstrating great potential for applications in energy storage. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes
NASA Technical Reports Server (NTRS)
Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.
2003-01-01
We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.
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NASA Astrophysics Data System (ADS)
Glukhova, O. E.; Slepchenkov, M. M.
2016-03-01
Using hybrid quantum mechanics/molecular mechanics (QM/MM) model we carried out investigation of interaction between phospholipid and carbon nanotube during indentation of high density lipoprotein (HDL). The object of investigation is armchair carbon nanotube with various diameters range from 0.5 to 1 nm. In a coarse of molecular dynamics study it is found that phospholipid partially penetrate into the cavity of nanotube with the chirality (7,7) and diameter of 0.9 nm. However, the entire molecule does not fit into nanospace of tube (7,7), so part of the head and the second phospholipid tail remain outside the carbon nanostructures. Using semi-empirical PM6 method it is established that during the indentation process the charged structured molecule fragments forming the high-density lipoprotein create local electric field near carbon nanotube (CNT) and continuously change electronic structure of CNT. However, the tube is not destroyed because the fields do not exceed the critical values of strength. The redistribution of the electron density on atom is observed in each time point.
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Lightweight Radiator System for a Spacecraft
NASA Technical Reports Server (NTRS)
Copeland, Robert J.; Mason, Georgia; Weislogel, Mark M.
2005-01-01
Three documents describe various aspects of a proposed lightweight, deployable radiator system for dissipating excess heat from the life-support system of a habitable spacecraft. The first document focuses on a radiator tube that would include a thin metal liner surrounded and supported by a thicker carbon-fiber-reinforced composite tubular structure that, in turn, would be formed as part of a unitary composite radiator-fin structure consisting mostly of a sheet of reticulated vitreous carbon laminated between carbon-fiber-reinforced face sheets. The thermal and mechanical properties, including the anisotropies, of the component materials are taken into account in the design. The second document describes thermo-structural bumpers, in the form of exterior multiple-ply carbon-fiber sheets enclosing hollows on opposite sides of a radiator fin, which would protect the radiator tube against impinging micrometeors and orbital debris. The third document describes a radiator system that would include multiple panels containing the aforementioned components, among others. The system would also include mechanisms for deploying the panels from compact stowage. Deployment would not involve breaking and remaking of fluid connections to the radiator panels.
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Liu, Dong; Yuan, Weiwei; Deng, Liangliang; Yu, Wenbin; Sun, Hongjuan; Yuan, Peng
2014-06-15
In this study, KOH activation was performed to enhance the porosity of the diatomite-templated carbon and to increase its adsorption capacity of methylene blue (MB). In addition to serving as the activation agent, KOH was also used as the etchant to remove the diatomite templates. Zeolite K-H was synthesized as a byproduct via utilization of the resultant silicon- and potassium-containing solutions created from the KOH etching of the diatomite templates. The obtained diatomite-based carbons were composed of macroporous carbon pillars and tubes, which were derived from the replication of the diatomite templates and were well preserved after KOH activation. The abundant micropores in the walls of the carbon pillars and tubes were derived from the break and reconfiguration of carbon films during both the removal of the diatomite templates and KOH activation. Compared with the original diatomite-templated carbons and CO2-activated carbons, the KOH-activated carbons had much higher specific surface areas (988 m(2)/g) and pore volumes (0.675 cm(3)/g). Moreover, the KOH-activated carbons possessed larger MB adsorption capacity (the maximum Langmuir adsorption capacity: 645.2 mg/g) than those of the original carbons and CO2-activated carbons. These results showed that KOH activation was a high effective activation method. The zeolite K-H byproduct was obtained by utilizing the silicon- and potassium-containing solution as the silicon and potassium sources. The zeolite exhibited a stick-like morphology and possessed nanosized particles with a mesopore-predominant porous structure which was observed by TEM for the first time. Copyright © 2014 Elsevier Inc. All rights reserved.
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Gupta, Shiva; Zhao, Shuai; Wang, Xiao Xia; ...
2017-10-31
The intrinsic instability of carbon largely limits its use for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a bifunctional catalyst in reversible fuel cells or water electrolyzers. In this paper, we discovered that Mn doping has a promotional role in stabilizing nanocarbon catalysts for the ORR/OER in alkaline media. Stable nanocarbon composites are derived from an inexpensive carbon/nitrogen precursor (i.e., dicyandiamide) and quaternary FeCoNiMn alloy via a template-free carbonization process. In addition to FeCoNiMn metal alloys/oxides, the carbon composites comprise substantial carbon tube forests growing on a thick and dense graphitic substrate. The dense carbon substratemore » with high degree of graphitization results from Mn doping, while active nitrogen-doped carbon tubes stem from FeCoNi. Catalyst structures and performance are greatly dependent on the doping content of Mn. Various accelerated stress tests (AST) and life tests verify the encouraging ORR/OER stability of the nanocarbon composite catalyst with optimal Mn doping. Extensive characterization before and after ASTs elucidates the mechanism of stability enhancement resulting from Mn doping, which is attributed to (i) hybrid carbon nanostructures with enhanced resistance to oxidation and (ii) the in situ formation of the β-MnO 2 and FeCoNi-based oxides capable of preventing carbon corrosion and promoting activity. Note that the improvement in stability due to Mn doping is accompanied by a slight activity loss due to a decrease in surface area. Finally, this work provides a strategy to stabilize carbon catalysts by appropriately integrating transition metals and engineering carbon structures.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Gupta, Shiva; Zhao, Shuai; Wang, Xiao Xia
The intrinsic instability of carbon largely limits its use for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) as a bifunctional catalyst in reversible fuel cells or water electrolyzers. In this paper, we discovered that Mn doping has a promotional role in stabilizing nanocarbon catalysts for the ORR/OER in alkaline media. Stable nanocarbon composites are derived from an inexpensive carbon/nitrogen precursor (i.e., dicyandiamide) and quaternary FeCoNiMn alloy via a template-free carbonization process. In addition to FeCoNiMn metal alloys/oxides, the carbon composites comprise substantial carbon tube forests growing on a thick and dense graphitic substrate. The dense carbon substratemore » with high degree of graphitization results from Mn doping, while active nitrogen-doped carbon tubes stem from FeCoNi. Catalyst structures and performance are greatly dependent on the doping content of Mn. Various accelerated stress tests (AST) and life tests verify the encouraging ORR/OER stability of the nanocarbon composite catalyst with optimal Mn doping. Extensive characterization before and after ASTs elucidates the mechanism of stability enhancement resulting from Mn doping, which is attributed to (i) hybrid carbon nanostructures with enhanced resistance to oxidation and (ii) the in situ formation of the β-MnO 2 and FeCoNi-based oxides capable of preventing carbon corrosion and promoting activity. Note that the improvement in stability due to Mn doping is accompanied by a slight activity loss due to a decrease in surface area. Finally, this work provides a strategy to stabilize carbon catalysts by appropriately integrating transition metals and engineering carbon structures.« less
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Development of radiocarbon-based methods to investigate atmospheric fossil carbon pollution
NASA Astrophysics Data System (ADS)
Major, István; Vodila, Gergely; Furu, Enikő; Kertész, Zsófia; Haszpra, László; Hajdas, Irka; Molnár, Mihály
2013-04-01
Gaseous and solid state carbon containing compounds significantly affect global climate change based on current atmospheric research results. Major part of the anthropogenic changes of the atmospheric carbon dioxide can be attributed to the combustion of fossil fuels and 95% of their emission is realised in the industrially active areas of the northern hemisphere. Anthropogenic carbonaceous aerosol particles play also a key role in the atmosphere modifying indirectly climate change and the quality of the environment and affecting directly human health. Since September 2008, the CO2 concentration of the air and its specific radiocarbon content (14C) has been monitored in the city of Debrecen (Hungary) and in a rural background site, Hegyhátsál (Hungary). To obtain a more representative view regarding anthropogenic contribution of the atmospheric carbon species, our measurement programme was enhanced by including the investigation of atmospheric aerosols in 2010. An aerosol cascade sampler for continuous monitoring was installed close to the atmospheric CO2 sampling station in the inner city of Debrecen. For 14C measurements, special sample preparation system and method was developed for the tiny total carbon content of the aerosol samples collected synchronously with the carbon dioxide observations. The radiocarbon measurement of the aerosol samples was performed by a high-sensitivity accelerator mass spectrometer (AMS) dedicated to environmental samples (EnvironMICADAS) developed together with ETH Zürich. The δ13C values of the samples were measured by the Dual Inlet system of a Delta PLUS XP Isotope Ratio Mass Spectrometer from the tiny CO2 amount aimed to reserve. The atmospheric fossil CO2 and fossil PM2.5 concentration variations show high similarity in the air of Debrecen city. During the winter heating period, due to the meteorological conditions (frequent thermal inversion, decreasing rate of mixing and upwelling), significantly higher total PM2.5 concentrations can be observed close to the surface, which is also reflected in the quantity of the total carbon. The trend of the fossil CO2 excess is very similar to the fossil carbon content of the total PM2.5. On the other hand during the winter time heating periods the extreme high observed aerosol concentrations in the city air seems to be caused by biomass combustion. It is well-visible from the aerosol C-14 measurements that the relative 14C content of the aerosol increases in the heating period in the PM2.5, even compared to the summer period. The trend of the measured stable isotope ratio also shows high similarity with the fossil carbon content of the PM2.5. The project was performed in part of the New Hungary Development Plan under Project No. GOP-1.3.1-09/A-2009-0032. The research was supported by the Hungarian NSF (OTKA-81515 and OTKA-77550). The publication is supported by the TÁMOP-4.2.2/B-10/1-2010-0024 project. The project was co-financed by the European Union and the European Social Fund.
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Development of a Low cost Ultra tiny Line Laser Range Sensor
2016-12-01
Development of a Low-cost Ultra-tiny Line Laser Range Sensor Xiangyu Chen∗, Moju Zhao∗, Lingzhu Xiang†, Fumihito Sugai∗, Hiroaki Yaguchi∗, Kei Okada...and Masayuki Inaba∗ Abstract— To enable robotic sensing for tasks with require- ments on weight, size, and cost, we develop an ultra-tiny line laser ...view customizable using different laser lenses. The optimal measurement range of the sensor is 0.05[m] ∼ 2[m]. Higher sampling rates can be achieved
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NASA Astrophysics Data System (ADS)
Kreitcberg, Alena
Severe plastic deformation (SPD) is commonly used for nanostructure formation in Ti-Ni shape memory alloys (SMAs), but it increases the risk of damage during processing and, consequently, negatively affects functional fatigue resistance of these materials. The principal objective of this project is, therefore, to study the interrelations between the processing conditions, damageability during processing, microstructure and the functional properties of Ti-Ni SMAs with the aim of improving long-term functional performances of these materials by optimizing their processing conditions. First, microstructure and fatigue properties of Ti-Ni SMAs were studied after thermomechanical treatment (TMT) with different combinations of severe cold and warm rolling (CR and WR), as well as intermediate and post-deformation annealing (IA and PDA) technological steps. It was shown that either when WR and IA were introduced into the TMT schedule, or CR intensity was decreased, the fatigue life was improved as a consequence of less processing-induced damage and higher density of the favorable B2-austenite texture. This improvement was reached, however, at a price of a lower multi-cycle functional stability of these materials, the latter being a direct consequence of the microstructure coarsening after higher-temperature lower-intensity processing. At the end of this study, however, it was not possible to distinguish between contributions to the functional performances of Ti-Ni SMAs from different processing-related features: a) grain/subgrain size; b) texture; and c) level of rolling-induced defects. To be capable of separating contributions to the functional properties of Ti-Ni alloys from grain/subgrain size and from texture, the theoretical crystallographic resource of recovery strain after different TMTs and, therefore, different textures, were calculated and compared with the experiment. The comparative analysis showed that the structural factors (grain/subgrain size) strongly dominate the texture contributions, and therefore, there is no real alternative to having nanocrystalline Ti-Ni alloys, if one needs to maximize the Ti-Ni alloys functional properties. Since the creation of such a microstructure requires the use of severe cold deformation techniques and neither of these techniques can be completely exempt from defects, it was deemed necessary to compare the damage tolerance of nanocrystalline Ti-Ni alloys to that of their nanosubgrained and mixed nanocrystalline/nanosubgrained counterparts. With this objective in mind, a detailed analysis of interrelations between the level of the CR/WR-induced damage (edge microcrack size and concentration) and the fatigue life of Ti- Ni SMAs was carried out. It was shown that nanocrystalline structure provides higher tolerance to small-crack propagation than nanosubgrained or mixed nanocrystalline/ nanosubgrained structures, and that low-temperature deformability of these alloys has to be improved to benefit from the property-enhancement potential of nanocrystalline structure. To broaden our knowledge in the field of Ti-Ni alloy deformability, the strain-rate sensitivity of these alloys was studied. Different microstructures, varying from the coarse- to ultrafinegrained, were created by means of equal-channel angular pressing (ECAP) and subjected to strain-rate sensitivity testing. As a result, the material with ultrafine-grained microstructure demonstrated an improved deformability as compared to the coarse-grained structure, at any deformation temperature. Moreover, it was determined that the smaller the grain size, the lower the temperature and the higher the strain-rate at which superplasticity occurs. Based on the results obtained, combined thermomechanical processing (ECAP at elevated temperatures followed by CR) was proposed and validated in terms of structural refinement with reduced level of processing-induced defects. Scientific contributions. This thesis contributes to the advancement of knowledge in the field of Ti-Ni SMAs' processing-structure-properties interactions, and the main conclusions of this study can be summed-up as follows: • Nanocrystalline Ti-Ni alloys significantly outperform nanosubgrain Ti-Ni alloys in terms of the absolute values and stability of their single- and multiple-cycle functional properties (superelasticity and shape memory characteristics). The main factor limiting the number of cycles to failure of the nanocrystalline alloys is the processingrelated damage. • The structure of Ti-Ni alloys plays significantly higher role in the realization of their functional potential that does their texture. • In terms of fatigue life, the nanocrystalline structure has lower small-crack sensitivity than does the nanosubgrained structure. • Grain refinement makes it possible to improve deformability of Ti-Ni alloys at any temperature. • To produce nanocrystalline Ti-Ni SMAs free of processing-induced-defects, a novel three-step processing is proposed (ECAP+CR+PDA): grain-refining severe plastic deformation at elevated temperatures (ECAP), followed-up by amorphizing SPD at low temperatures (CR), and ended-up by nanocrystallizing post-deformation heat treatment (PDA).
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NASA Astrophysics Data System (ADS)
Meisner, L. L.; Markov, A. B.; Ozur, G. E.; Rotshtein, V. P.; Yakovlev, E. V.; Meisner, S. N.; Poletika, T. M.; Girsova, S. L.; Semin, V. O.; Mironov, Yu P.
2017-05-01
TiNi shape memory alloys (SMAs) are unique metallic biomaterials due to combination of superelastisity and high corrosion resistance. Important factors limiting biomedical applications of TiNi SMAs are a danger of toxic Ni release into the adjacent tissues, as well as insufficient level of X-ray visibility. In this paper, the method for fabrication of protective Ni-free surface alloy of thickness ∼1 μm of near Ti70Ta30 composition on TiNi SMA substrate has been successfully realized. The method is based on multiple alternation of magnetron co-deposition of Ti70Ta30 thin (50 nm) films and their liquid-phase mixing with the TiNi substrate by microsecond low-energy, high current electron beam (≤15 keV, ∼2 J/cm2) using setup RITM-SP (Microsplav, Russia). It was found by AES, XRD, SEM/EDS and HRTEM/EDS examinations, that Ti-Ta surface alloy has an increased X-ray visibility and gradient multiphase amorphous-nanocrystalline structure containing nanopores.
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NASA Astrophysics Data System (ADS)
Guo, Yonghong; Zhai, Gang; Ru, Yu; Wu, Chuyu; Jia, Xiaowei; Sun, Yaping; Yu, Jiawen; Kang, Zhizhong; Sun, Baomin
2018-03-01
The Flame pyrolysis method used to synthesize carbon nanotubes was studied in this work. In order to improve the quality of synthesized carbon nanotubes, it is important to change the corresponding natures of the catalyst. Two catalyst preparation methods, namely, the sol-gel method and the impregnation method, were compared in this experiment. The properties of the catalyst are analyzed in depth by energy dispersive spectrometer (EDS), x-ray diffraction (XRD), temperature program reduction (TPR). The generation of carbon nanotubes was systematically analysed through scanning electron microscope (SEM), molecule dynamics (MD), raman spectroscopy and transmission electron microscope (TEM). The results show that the catalysts prepared by the impregnation method are stickier, dispersed and easier to dip onto the probe or substrate, which is beneficial for the large-scale production of carbon tubes. The specific surface area of alumina is larger and the iron and molybdenum oxide are more evenly dispersed on the surface of alumina. The carbon nanotubes produced by the catalysts prepared by impregnation method are flatter and have less impurities. The ratio of ID/IG+ is 29.7% lower than that of the sol-gel method in the Raman spectra. The TEM statistics show that the average diameter of the carbon tubes decreases by 23.3%. Therefore, the impregnation method can improve the quality of carbon nanotubes in the case of a similar degree of difficulty in the preparation of the catalyst.
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NASA Technical Reports Server (NTRS)
Kaul, Anupama B.; Megerian, Krikor G.; von Allmen, Paul; Kowalczyk, Robert; Baron, Richard
2009-01-01
We have developed manufacturable approaches to form single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 micron deep trenches. These wafer-scale approaches were enabled by chemically amplified resists and inductively coupled Cryo-etchers for forming the 3D nanoscale architectures. The tube growth was performed using dc plasma-enhanced chemical vapor deposition (PECVD), and the materials used for the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. Tube characteristics were also engineered to some extent, by adjusting growth parameters, such as Ni catalyst thickness, pressure and plasma power during growth. Such scalable, high throughput top-down fabrication techniques, combined with bottom-up tube synthesis, should accelerate the development of PECVD tubes for applications such as interconnects, nano-electromechanical (NEMS), sensors or 3D electronics in general.
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Pulsed electron beam propagation in gases under pressure of 6.6 kPa in drift tube
NASA Astrophysics Data System (ADS)
Kholodnaya, G. E.; Sazonov, R. V.; Ponomarev, D. V.; Remnev, G. E.; Poloskov, A. V.
2017-02-01
This paper presents the results of an investigation of pulsed electron beam transport propagated in a drift tube filled with different gases (He, H2, N2, Ar, SF6, and CO2). The total pressure in the drift tube was 6.6 kPa. The experiments were carried out using a TEA-500 pulsed electron accelerator. The electron beam was propagated in the drift tube composed of two sections equipped with reverse current shunts. Under a pressure of 6.6 kPa, the maximum value of the electron beam charge closed on the walls of the drift tube was recorded when the beam was propagated in hydrogen and carbon dioxide. The minimum value of the electron beam charge closed on the walls of the drift tube was recorded for sulfur hexafluoride. The visualization of the pulsed electron beam energy losses onto the walls of the drift chamber was carried out using radiation-sensitive film.
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A pulsed neutron generator for in vivo body composition studies
NASA Astrophysics Data System (ADS)
Weinlein, J. H.; O'Neal, M. L.; Bacon, F. M.
1991-05-01
A neutron generator system utilizing two Zetatron neutron tubes has been designed and delivered to the U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University for use in clinical measurements of body carbon by neutron inelastic scattering. Each neutron tube is capable of delivering 10 3-10 4 14-MeV neutrons in a 7-μs pulse at repetition rates of 4 or 8 kHz, and can be operated independently as well as in a master-slave mode. The neutron tubes are gas filled with a mixture of deuterium and tritium; the target of the tube is operated at - 30 to - 60 kV dc and the ion source is operated with a 2.5-kV, 7-μs pulse. The tube gas pressure is monitored and controlled by measuring the total current in the high voltage circuit and feeding it back to the gas-reservoir drive circuit. Neutrons were measured with a plastic scintillator and photomultiplier tube.
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Structure-dependent performance of TiO 2/C as anode material for Na-ion batteries
DOE Office of Scientific and Technical Information (OSTI.GOV)
He, Hanna; Gan, Qingmeng; Wang, Haiyan
The performance of energy storage materials is highly dependent on their nanostructures. Herein, hierarchical rod-in-tube TiO 2 with a uniform carbon coating is synthesized as the anode material for sodium-ion batteries by a facile solvothermal method. This unique structure consists of a tunable nanorod core, interstitial hollow spaces, and a functional nanotube shell assembled from two-dimensional nanosheets. By adjusting the types of solvents used and reaction time, the morphologies of TiO 2/C composites can be tuned to nanoparticles, microrods, rod-in-tube structures, or microtubes. Among these materials, rod-in-tube TiO 2 with a uniform carbon coating shows the highest electronic conductivity, specificmore » surface area (336.4 m(2) g(-1)), and porosity, and these factors lead to the best sodium storage capability. Benefiting from the unique structural features and improved electronic/ionic conductivity, the as-obtained rod-in-tube TiO2/C in coin cell tests exhibits a high discharge capacity of 277.5 and 153.9 mAh g(-1) at 50 and 5000 mA g(-1), respectively, and almost 100% capacity retention over 14,000 cycles at 5000 mA g(-1). In operando high-energy X-ray diffraction further confirms the stable crystal structure of the rod-in-tube TiO 2/C during Na+ insertion/extraction. This work highlights that nanostructure design is an effective strategy to achieve advanced energy storage materials.« less
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Desktop Systems for Manufacturing Carbon Nanotube Films by Chemical Vapor Deposition
2007-06-01
existing low cost tube furnace designs limit the researcher’s ability to fully separate critical reaction parameters such as temperature and flow...Often heated using an external resistive heater coil, a typical configuration, shown in Figure 4, might place a tube made of a non- reactive ...researcher’s ability to fully separate critical parameters such as temperature and flow profiles. Additionally, the use of heating elements external to
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Role of surfactants in carbon nanotubes density gradient separation.
Carvalho, Elton J F; dos Santos, Maria Cristina
2010-02-23
Several strategies aimed at sorting single-walled carbon nanotubes (SWNT) by diameter and/or electronic structure have been developed in recent years. A nondestructive sorting method was recently proposed in which nanotube bundles are dispersed in water-surfactant solutions and submitted to ultracentrifugation in a density gradient. By this method, SWNTs of different diameters are distributed according to their densities along the centrifuge tube. A mixture of two anionic amphiphiles, namely sodium dodecylsulfate (SDS) and sodium cholate (SC), presented the best performance in discriminating nanotubes by diameter. We present molecular dynamics studies of the water-surfactant-SWNT system. The simulations revealed one aspect of the discriminating power of surfactants: they can actually be attracted toward the interior of the nanotube cage. The binding energies of SDS and SC on the outer nanotube surface are very similar and depend weakly on diameter. The binding inside the tubes, on the contrary, is strongly diameter dependent: SDS fits best inside tubes with diameters ranging from 8 to 9 A, while SC is best accommodated in larger tubes, with diameters in the range 10.5-12 A. The dynamics at room temperature showed that, as the amphiphile moves to the hollow cage, water molecules are dragged together, thereby promoting the nanotube filling. The resulting densities of filled SWNT are in agreement with measured densities.
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NASA Astrophysics Data System (ADS)
Hatada, R.; Flege, S.; Bobrich, A.; Ensinger, W.; Dietz, C.; Baba, K.; Sawase, T.; Watamoto, T.; Matsutani, T.
2014-08-01
Adhesive diamond-like carbon (DLC) films can be prepared by plasma source ion implantation (PSII), which is also suitable for the treatment of the inner surface of a tube. Incorporation of a metal into the DLC film provides a possibility to change the characteristics of the DLC film. One source for the metal is DC sputtering. In this study PSII and DC sputtering were combined to prepare DLC films containing low concentrations of Ag on the interior surfaces of stainless steel tubes. A DLC film was deposited using a C2H4 plasma with the help of an auxiliary electrode inside of the tube. This electrode was then used as a target for the DC sputtering. A mixture of the gases Ar and C2H4 was used to sputter the silver. By changing the gas flow ratios and process time, the resulting Ag content of the films could be varied. Sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, atomic force microscopy and Raman spectroscopy. Additionally, a ball-on-disk test was performed to investigate the tribological properties of the films. The antibacterial activity was determined using Staphylococcus aureus bacteria.
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... the tiny working units of the kidneys that filter wastes and remove extra fluid from the blood. ... the tiny working units of the kidneys that filter wastes and remove extra fluid from the blood. ...
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Colburn, W A; Vane, F M; Bugge, C J; Carter, D E; Bressler, R; Ehmann, C W
1985-01-01
The pharmacokinetics of isotretinoin and 4-oxoisotretinoin in blood, as well as the blood concentrations and urinary, biliary, and fecal excretion of carbon-14 were studied using liquid scintillation counting techniques and reverse phase HPLC methods following a single 80-mg oral suspension dose of 14C-isotretinoin to four healthy male subjects and two patients with biliary T-tube drainage. Approximately 80% of the dose was recovered as 14C in excreta during the course of the study of which about equal fractions were in the urine and feces. Secondary peaks in blood concentrations of 14C were observed in the healthy subjects whereas they were not seen in the patients with T-tubes. The harmonic mean apparent half-life for isotretinoin in the blood of the healthy subjects was 13.6 hr, whereas the corresponding value for the 14C was 90 hr. Although a rigorous comparison of pharmacokinetic parameters between healthy subjects and T-tube patients was not feasible due to the limited number of subjects studied, comparisons of certain trends in the pharmacokinetic profiles gave some possible insights into the role of biliary excretion and enterohepatic cycling on the disposition of isotretinoin. The data for isotretinoin and 4-oxoisotretinoin coupled with the total carbon-14 data suggest that the oral dose of 14C-isotretinoin is absorbed to a similar extent by the healthy subjects and T-tube patients, whereas T-tube patients clear the drug more rapidly. The biliary excretion and possible enterohepatic circulation of isotretinoin and its metabolites may have significant impact on the pharmacokinetic profile of isotretinoin in man.
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Migration of a carbon adatom on a charged single-walled carbon nanotube
Han, Longtao; Krstic, Predrag; Kaganovich, Igor; ...
2017-02-02
Here we find that negative charges on an armchair single-walled carbon nanotube (SWCNT) can significantly enhance the migration of a carbon adatom on the external surfaces of SWCNTs, along the direction of the tube axis. Nanotube charging results in stronger binding of adatoms to SWCNTs and consequent longer lifetimes of adatoms before desorption, which in turn increases their migration distance several orders of magnitude. These results support the hypothesis of diffusion enhanced SWCNT growth in the volume of arc plasma. This process could enhance effective carbon flux to the metal catalyst.
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NASA Astrophysics Data System (ADS)
An, Bai; Fukuyama, Seiji; Yokogawa, Kiyoshi; Yoshimura, Masamichi
1998-06-01
Carbon nanotubes deposited on highly oriented pyrolytic graphite (HOPG) are annealed in ultra high vacuum. The effect of annealing temperature on the surface morphology of the carbon nanotubes on HOPG is examined by scanning tunneling microscopy. The ring-like surface superstructure of (\\sqrt {3}× \\sqrt {3})R30° of graphite is found on the carbon nanotubes annealed above 1593 K. The tips of the carbon nanotubes are destroyed and the stacking misarrangement between the upper and the lower walls of the tube join with HOPG resulting in the superstructure.
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Apparatus and process for the surface treatment of carbon fibers
DOE Office of Scientific and Technical Information (OSTI.GOV)
Paulauskas, Felix Leonard; Ozcan, Soydan; Naskar, Amit K.
A method for surface treating a carbon-containing material in which carbon-containing material is reacted with decomposing ozone in a reactor (e.g., a hollow tube reactor), wherein a concentration of ozone is maintained throughout the reactor by appropriate selection of at least processing temperature, gas stream flow rate, reactor dimensions, ozone concentration entering the reactor, and position of one or more ozone inlets (ports) in the reactor, wherein the method produces a surface-oxidized carbon or carbon-containing material, preferably having a surface atomic oxygen content of at least 15%. The resulting surface-oxidized carbon material and solid composites made therefrom are also described.
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HST PSF simulation using Tiny Tim
NASA Technical Reports Server (NTRS)
Krist, J. E.
1992-01-01
Tiny Tim is a program which simulates Hubble Space Telescope imaging camera PSF's. It is portable (written and distributed in C) and is reasonably fast. It can model the WFPC, WFPC 2, FOC, and COSTAR corrected FOC cameras. In addition to aberrations such as defocus and spherical, it also includes WFPC obscuration shifting, mirror zonal error maps, and jitter. The program has been used at a number of sites for deconvolving HST images. Tiny Tim is available via anonymous ftp on stsci.edu in the directory software/tinytim.
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Design Optimization and Development of Tubular Isogrid Composites Tubes for Lower Limb Prosthesis
NASA Astrophysics Data System (ADS)
Junqueira, Diego Morais; Gomes, Guilherme Ferreira; Silveira, Márcio Eduardo; Ancelotti, Antonio Carlos
2018-04-01
From the beginnings of humanity, natural or unnatural misfortunes such as illnesses, wars, automobile accidents cause loss of body limbs like teeth, arms, legs, etc. The solution found for the replacement of these missing limbs is in the use of prostheses. Lower limbs tubes or pylons are prosthetics components that are claimed to support loads during walking and other daily tasks activities. Commonly, prosthetic tubes are manufactured using metal materials such as stainless steel, aluminum and titanium. The mass of these tubes is generally high compared to tubes made of carbon fiber reinforced polymer matrix (CFRP) composite. Therefore, this work has the objective of design, manufacturing and analyzing the feasibility of a new tube concept, made of composite material, which makes use of lattice structure and inner layer. Until the present moment, lower limb prosthesis tubes using lattice structure and ineer layer have never been studied and/or tested to date. It can be stated that the tube of rigid ribs with inner layer and angle of 40° is more efficient than those of 26° and 30°. The proposed design allows a structural weight reduction in high performance prostheses from 120 g to 40 g.
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NASA Astrophysics Data System (ADS)
Yuan, Ming; Zhong, Ruibo; Gao, Haiyang; Li, Wanrong; Yun, Xiaoling; Liu, Jingran; Zhao, Xinmin; Zhao, Guofen; Zhang, Feng
2015-11-01
The use of biomass as renewable and sustainable energy source has attracted the attention of politics and research and development (R&D) facilities around the world. Agricultural straw acts as a typical biowaste, which still needs highly effective recycling to save the biomass urgently at present. Photoluminescent carbon dots (C-dots) are novel biocompatible nanomaterials that have been proved to be produced from many carbon-abundant materials and hold great promise for the modern nanobiomedicine. In order to realize a "one-stone-two-birds" strategy, we report a green, economic, one-pot method in this article for synthesizing photoluminescent C-dots by hydrothermal treatment of wheat straw. Using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), we show that the as-prepared C-dots are amorphous in structure and are mainly composed of carbon. Their tiny size (<2 nm), combined with the characteristic excitation-dependent relatively bright emission, and robust photostability made the C-dots a potential biocompatible nanomaterial for bio-applications. We have experimentally demonstrated their potential applications in biomedical labeling, imaging, and sensing/detecting. The high yield (∼20%) of C-dots from wheat straw may suggest a new economic strategy for recycling biowaste.
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Synthesis of highly phase pure BSCCO superconductors
Dorris, S.E.; Poeppel, R.B.; Prorok, B.C.; Lanagan, M.T.; Maroni, V.A.
1995-11-21
An article and method of manufacture (Bi, Pb)-Sr-Ca-Cu-O superconductor are disclosed. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor. 5 figs.
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Synthesis of highly phase pure BSCCO superconductors
Dorris, Stephen E.; Poeppel, Roger B.; Prorok, Barton C.; Lanagan, Michael T.; Maroni, Victor A.
1995-01-01
An article and method of manufacture of (Bi, Pb)-Sr-Ca-Cu-O superconductor. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor.
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Synthesis of highly phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor
Dorris, Stephen E.; Poeppel, Roger B.; Prorok, Barton C.; Lanagan, Michael T.; Maroni, Victor A.
1994-01-01
An article and method of manufacture of (Bi,Pb)-Sr-Ca-Cu-O superconductor. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi,Pb)-Sr-Ca-Cu-O superconductor.
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Shock-tube thermochemistry tables for high-temperature gases. Volume 5: Carbon dioxide
NASA Technical Reports Server (NTRS)
Menard, W. A.; Horton, T. E.
1971-01-01
Equilibrium thermodynamic properties and species concentrations for carbon dioxide are tabulated for moving, standing, and reflected shock waves. Initial pressures range from 6.665 to 6665 N/sq m (0.05 to 50.0 torr), and temperatures from 2,000 to over 80,000K. In this study, 20 molecular and atomic species were considered.
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Age of Walden Creek Group: Can it be demonstrated--Biostratigraphically
DOE Office of Scientific and Technical Information (OSTI.GOV)
Broadhead, T.W.; Hatcher, R.D. Jr.; Walker, K.R.
The Walden Creek Group (WCG) is a lithologically heterogeneous succession of sedimentary rocks exposed in the western Blue Ridge of the southern Appalachians. Carbonate rocks of the WCG occur as bedded limestone in the Sandsuck Formation and subjacent Wilhite and as limestone clasts in polymict conglomerate bodies within the Sandsuck, Wilhite, and the underlying Shields Formation. Petrographically, these carbonate rocks exhibit a shallow marine aspect. Locally abundant pisoids, ooids and peloids occur in a preservational continuum ranging from well-preserved internal fabrics to relict spar-filled micrite envelopes. Pisoids, occurring in grainstone and wackestone fabrics, resemble oversized marine ooids characteristic of Uppermore » Proterozoic carbonated rocks of Greenland and Spitzbergen. Recent reports of metazoan and foraminiferal fossils from the Wilhite Formation have cast doubt on its long-regarded Late Proterozoic age. The fossils the authors have observed include algal oncolites, minute fecal pellets, and extremely rare cyanobacterial filament sheaths and skeletal fragments of uncertain biological affinity. Good quality preservation of allochems in WCG carbonate rocks is important in evaluating the absence of undoubted Paleozoic fossils. Dominant components of Paleozoic biotas: crinoids, brachiopods, and bryozoans would be recognizable, even as tiny fragments. The absence of conodonts further suggests that carbonate rocks of the WCG predate the appearance of abundant skeletonized biota and are probably Late Proterozoic. The authors propose that both bedded carbonate rocks and carbonate clasts of the WCG are essentially contemporaneous with each other and reflect carbonate bank conditions that developed toward the end of Late Proterozoic clastic deposition, which filled rift basins that formed along the southeastern Laurentian margin. Episodic reactivation accounts for the occurrence of carbonate clasts in several parts of the WCG and Snowbird Group.« less
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NASA Astrophysics Data System (ADS)
Moradian, Rostam; Behzad, Somayeh; Chegel, Raad
2008-10-01
By using ab initio density functional theory the structural and electronic properties of isolated and bundled (8,0) and (6,6) silicon carbide nanotubes (SiCNTs) are investigated. Our results show that for such small diameter nanotubes the inter-tube interaction causes a very small radial deformation, while band splitting and reduction of the semiconducting energy band gap are significant. We compared the equilibrium interaction energy and inter-tube separation distance of (8,0) SiCNT bundle with (10,0) carbon nanotube (CNT) bundle where they have the same radius. We found that there is a larger inter-tube separation and weaker inter-tube interaction in the (8,0) SiCNT bundle with respect to (10,0) CNT bundle, although they have the same radius.
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2011-12-19
A pair of Saturn moons appear insignificant compared to the immensity of the planet. Enceladus is at left, Epimetheus appears as a tiny black speck on the far left in this image from NASA Cassini spacecraft.
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Phytoplankton bloom in the Black Sea
NASA Technical Reports Server (NTRS)
2002-01-01
Brightly colored waters in the Black Sea give evidence of the growth of tiny marine plants called phytoplankton, which contain chlorophyll and other pigments that reflect light different ways, producing the colorful displays. The very bright blue waters could be an organism called a coccolithophores, which has a highly reflective calcium carbonate coating that appears bright blue (or sometimes white) in true-color (visible) imagery. However, other organisms, such as cyanobacteria can also appear that color, and so often scientists will compare the ratios of reflectance at one wavelength of light to another to decide what organisms might be present. This series of images shows a bloom occurring in the Black Sea from May 11, 2002, to May 18.
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Kim, Donghwan; Lee, Hyunsuk; Bae, Joohyeon; Jeong, Hyomin; Choi, Byeongkeun; Nam, Taehyun; Noh, Jungpil
2018-09-01
Ti-Ni shape memory alloy (SMA) thin films are very attractive material for industrial and medical applications such as micro-actuator, micro-sensors, and stents for blood vessels. An important property besides shape memory effect in the application of SMA thin films is the adhesion between the film and the substrate. When using thin films as micro-actuators or micro-sensors in MEMS, the film must be strongly adhered to the substrate. On the other hand, when using SMA thin films in medical devices such as stents, the deposited alloy thin film must be easily separable from the substrate for efficient processing. In this study, we investigated the effect of substrate roughness on the adhesion of Ti-Ni SMA thin films, as well as the structural properties and phase-transformation behavior of the fabricated films. Ti-Ni SMA thin films were deposited onto etched glass substrates with magnetron sputtering. Radio frequency plasma was used for etching the substrate. The adhesion properties were investigated through progressive scratch test. Structural properties of the films were determined via Feld emission scanning electron microscopy, X-ray diffraction measurements (XRD) and Energy-dispersive X-ray spectroscopy analysis. Phase transformation behaviors were observed with differential scanning calorimetry and low temperature-XRD. Ti-Ni SMA thin film deposited onto rough substrate provides higher adhesive strength than smooth substrate. However the roughness of the substrate has no influence on the growth and crystallization of the Ti-Ni SMA thin films.
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Phukaoluan, Aphinan; Khantachawana, Anak; Kaewtatip, Pongpan; Dechkunakorn, Surachai; Kajornchaiyakul, Julathep
2016-09-01
The purpose of this study was to investigate improved performances of TiNi in order to promote tooth movement. Special attention was paid to the effect on the clinical properties of TiNi of adding Cu and Co to this alloy. Ti49.4Ni50.6, Ti49Ni46Cu5 and Ti50Ni47Co3 (at %) alloys were prepared. Specimens were cold-rolled at 30% reduction and heat-treated at 400°C for 60min. Then, the test results were compared with two types of commercial archwires. The findings showed that superelasticity properties were confirmed in the manufactured commercial alloys at mouth temperature. The difference of stress plateau in TiNi, TiNiCo and commercial wires B at 25°C changed significantly at various testing temperatures due to the combination of martensite and austenite phases. At certain temperatures the alloys exhibited zero recovery stress at 2% strain and consequently produced zero activation force for moving teeth. The corrosion test showed that the addition of Cu and Co to TiNi alloys generates an increase in corrosion potential (Ecorr) and corrosion current densities (Icorr). Finally, we observed that addition of Cu and Co improved cell viability. We conclude that addition of an appropriate amount of a third alloying element can help enhance the performances of TiNi orthodontic archwires. Copyright © 2016 CEO. Published by Elsevier Masson SAS. All rights reserved.
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Hot Corrosion at Air-Ports in Kraft Recovery Boilers
DOE Office of Scientific and Technical Information (OSTI.GOV)
Holcomb, Gordon R.; Covino, Bernard S., Jr.; Russell, James H.
2003-01-01
Hot corrosion can occur on the cold-side of airports in Kraft recovery boilers. The primary corrosion mechanism involves the migration of sodium hydroxide and potassium hydroxide vapors through leaks in the furnace wall at the airports and their subsequent condensation. It has been reported that stainless steel is attacked much faster than carbon steel in composite tubes, and that carbon steel tubing, when used with a low-chromium refractory, does not exhibit this type of corrosion. For hot corrosion fluxing of metal oxides, either acidic or basic fluxing takes place, with a solubility minimum at the basicity of transition between themore » two reactions. For stainless steel, if the basicity of the fused salt is between the iron and chromium oxide solubility minima, then a synergistic effect can occur that leads to rapid corrosion. The products of one reaction are the reactants of the other, which eliminates the need for rate-controlling diffusion. This effect can explain why stainless steel is attacked more readily than carbon steel.« less
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Fu, Li; Merabia, Samy; Joly, Laurent
2018-04-19
Following our recent theoretical prediction of the giant thermo-osmotic response of the water-graphene interface, we explore the practical implementation of waste heat harvesting with carbon-based membranes, focusing on model membranes of carbon nanotubes (CNT). To that aim, we combine molecular dynamics simulations and an analytical model considering the details of hydrodynamics in the membrane and at the tube entrances. The analytical model and the simulation results match quantitatively, highlighting the need to take into account both thermodynamics and hydrodynamics to predict thermo-osmotic flows through membranes. We show that, despite viscous entrance effects and a thermal short-circuit mechanism, CNT membranes can generate very fast thermo-osmotic flows, which can overcome the osmotic pressure of seawater. We then show that in small tubes confinement has a complex effect on the flow and can even reverse the flow direction. Beyond CNT membranes, our analytical model can guide the search for other membranes to generate fast and robust thermo-osmotic flows.
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Micro-tube biotemplate synthesis of Fe3O4/C composite as anode material for lithium-ion batteries
NASA Astrophysics Data System (ADS)
Du, Jun; Ding, Yu; Guo, Liangui; Wang, Li; Fu, Zhengbing; Qin, Caiqin; Wang, Feng; Tao, Xinyong
2017-12-01
Kapok fibres were used as micro-tube biotemplate and bio-carbon source to synthesise Fe3O4/C composites, which were then utilised as anode materials. Fe3O4 nanoparticles were grown uniformly onto the external surface and internal channel of kapok carbon fibres. The flexibility, high specific surface area and electronic conduction of kapok fibres can buffer the volume expansion as well as inhibit the aggregation of Fe3O4 nanoparticles. Thus, the electrical integrity and structural of the Fe3O4/C composites electrode during lithiation/delithiation processes. The Fe3O4/C composites electrode delivers a high reversible capacity of 596 mA h g-1 after 100 cycles and an ultra-high coulombic efficiency approaching 100%. The high electrochemical performance of the Fe3O4/C composites can be caused by the synergistic effect of the Fe3O4 nanoparticles and the structure of kapok carbon fibres.
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A parametric study of single-wall carbon nanotube growth by laser ablation
NASA Technical Reports Server (NTRS)
Arepalli, Sivaram; Holmes, William A.; Nikolaev, Pavel; Hadjiev, Victor G.; Scott, Carl D.
2004-01-01
Results of a parametric study of carbon nanotube production by the double-pulse laser oven process are presented. The effect of various operating parameters on the production of single-wall carbon nanotubes (SWCNTs) is estimated by characterizing the nanotube material using analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermo gravimetric analysis and Raman spectroscopy. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure, flow rate, inner tube diameter, as well as its material, and oven temperature. It was found that the material quality and quantity improve with deviation from normal operation parameters such as laser energy density higher than 1.5 J/cm2, pressure lower than 67 kPa, and flow rates higher than 100 sccm. Use of helium produced mainly small diameter tubes and a lower yield. The diameter of SWCNTs decreases with decreasing oven temperature and lower flow rates.
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Mössbauer characterization of joints of steel pieces in transient liquid phase bonding experiences
NASA Astrophysics Data System (ADS)
di Luozzo, N.; Martínez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B.
2011-11-01
Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Mössbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.
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NASA Technical Reports Server (NTRS)
Cook, W. J.
1973-01-01
A theoretical study of heat transfer for zero pressure gradient hypersonic laminar boundary layers for various gases with particular application to the flows produced in an expansion tube facility was conducted. A correlation based on results obtained from solutions to the governing equations for five gases was formulated. Particular attention was directed toward the laminar boundary layer shock tube splitter plates in carbon dioxide flows generated by high speed shock waves. Computer analysis of the splitter plate boundary layer flow provided information that is useful in interpreting experimental data obtained in shock tube gas radiation studies.
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NASA Astrophysics Data System (ADS)
Mitchell, Daniel Robert
A brief introduction to carbon chemistry is given with an emphasis on the use high-temperature reactions that use carbon vapor, generated from graphite, to synthesize nano-structured materials. Laser and electric are ablation of graphite was utilized to create a variety of high carbon content materials ranging from discrete acetylenic molecules to extremely large multi-wall nanotubes. A new synthesis for large carbon nanotubes, containing 1--5 atom percent nitrogen bound into the graphite lattice, was realized by the reaction of carbon vapor, nickel/yttrium catalyst and cyanogen gas. These carbon "megatubes" were then employed as a substrate to tether a wide variety of molecules both inorganic and organic. The megatubes, in their native and derivatized states, were then assembled into simple circuits to explore their electronic transport properties. Direct fluorination was used to post-treat the surface of the multi-wall carbon nanotubes in order to alter the inherent physical and chemical properties of the tubes, as well as to serve as another route to functionalize their surfaces. Fluorine sites on the walls of the tube were allowed to react with Grignard reagents to produce nantoubes with the chosen alkyl chemically bonded to the surface. Products were characterized with techniques similar to unfluorinated tubules. Using similar carbon vaporization techniques, sp-hybridized carbon chain compounds were synthesized. Using a one-step method dicyanopolyynes were synthesized and characterized with nuclear magnetic resonance and mass spectroscopy, containing up to 8 acetylenic repeat units. A two-step method was also utilized to create polyynes terminated with trifluoromethyl or nitrile radicals generated in a capacitively coupled radio frequency glow plasma discharge. A partial characterization of these products was accomplished with nuclear magnetic resonance, mass, and infrared spectroscopy techniques.
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2014-03-27
between the nozzle /shroud tube interface, where the liquid is allowed to rapidly expand from the smaller diameter of the nozzle into the larger diameter...the CO2(l) freezes and agglomerates in the shroud tube, producing particles that are larger than if the liquid were expanded through a single nozzle ...Traditional seeding materials used for gas flows . . . . . . . . . . . . . . . . . 17 2.6 Example correlation peak for one IR in PIV
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Pla-Tolós, J; Serra-Mora, P; Hakobyan, L; Molins-Legua, C; Moliner-Martinez, Y; Campins-Falcó, P
2016-11-01
In this work, in-tube solid phase microextraction (in-tube SPME) coupled to capillary LC (CapLC) with diode array detection has been reported, for on-line extraction and enrichment of booster biocides (irgarol-1051 and diuron) included in Water Frame Directive 2013/39/UE (WFD). The analytical performance has been successfully demonstrated. Furthermore, in the present work, the environmental friendliness of the procedure has been quantified by means of the implementation of the carbon footprint calculation of the analytical procedure and the comparison with other methodologies previously reported. Under the optimum conditions, the method presents good linearity over the range assayed, 0.05-10μg/L for irgarol-1051 and 0.7-10μg/L for diuron. The LODs were 0.015μg/L and 0.2μg/L for irgarol-1051 and diuron, respectively. Precision was also satisfactory (relative standard deviation, RSD<3.5%). The proposed methodology was applied to monitor water samples, taking into account the EQS standards for these compounds. The carbon footprint values for the proposed procedure consolidate the operational efficiency (analytical and environmental performance) of in-tube SPME-CapLC-DAD, in general, and in particular for determining irgarol-1051 and diuron in water samples. Copyright © 2016 Elsevier B.V. All rights reserved.
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Bending fracture in carbon nanotubes.
Kuo, Wen-Shyong; Lu, Hsin-Fang
2008-12-10
A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed.
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Naumann, Meike; Schäfer, Christian; Brandner, Armin; Hofmann, Heiko J; Claus, Peter
2011-01-01
Summary Polymethylmethacrylate (PMMA)/ceria composite fibres were synthesized by using a sequential combination of polymer electrospinning, spray-coating with a sol, and a final calcination step to yield microstructured ceria tubes, which are composed of nanocrystalline ceria particles. The PMMA template is removed from the organic/inorganic hybrid material by radio frequency (rf) plasma etching followed by calcination of the ceramic green-body fibres. Microsized ceria (CeO2) tubes, with a diameter of ca. 0.75 µm, composed of nanocrystalline agglomerated ceria particles were thus obtained. The 1-D ceramic ceria material was characterized by X-ray diffraction, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV–vis and photoluminescence spectroscopy (PL), as well as thermogravimetric analysis (TGA). Its catalytic performance was studied in the direct carboxylation of methanol with carbon dioxide leading to dimethyl carbonate [(CH3O)2CO, DMC], which is widely employed as a phosgene and dimethyl sulfate substitute, and as well as a fuel additive. PMID:22259761
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Study on voids of epoxy matrix composites sandwich structure parts
NASA Astrophysics Data System (ADS)
He, Simin; Wen, Youyi; Yu, Wenjun; Liu, Hong; Yue, Cheng; Bao, Jing
2017-03-01
Void is the most common tiny defect of composite materials. Porosity is closely related to composite structure property. The voids forming behaviour in the composites sandwich structural parts with the carbon fiber reinforced epoxy resin skins was researched by adjusting the manufacturing process parameters. The composites laminate with different porosities were prepared with the different process parameter. The ultrasonic non-destructive measurement method for the porosity was developed and verified through microscopic examination. The analysis results show that compaction pressure during the manufacturing process had influence on the porosity in the laminate area. Increasing the compaction pressure and compaction time will reduce the porosity of the laminates. The bond-line between honeycomb core and carbon fiber reinforced epoxy resin skins were also analyzed through microscopic examination. The mechanical properties of sandwich structure composites were studied. The optimization process parameters and porosity ultrasonic measurement method for composites sandwich structure have been applied to the production of the composite parts.
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Electrical property of macroscopic graphene composite fibers prepared by chemical vapor deposition.
Sun, Haibin; Fu, Can; Gao, Yanli; Guo, Pengfei; Wang, Chunlei; Yang, Wenchao; Wang, Qishang; Zhang, Chongwu; Wang, Junya; Xu, Junqi
2018-07-27
Graphene fibers are promising candidates in portable and wearable electronics due to their tiny volume, flexibility and wearability. Here, we successfully synthesized macroscopic graphene composite fibers via a two-step process, i.e. first electrospinning and then chemical vapor deposition (CVD). Briefly, the well-dispersed PAN nanofibers were sprayed onto the copper surface in an electrified thin liquid jet by electrospinning. Subsequently, CVD growth process induced the formation of graphene films using a PAN-solid source of carbon and a copper catalyst. Finally, crumpled and macroscopic graphene composite fibers were obtained from carbon nanofiber/graphene composite webs by self-assembly process in the deionized water. Temperature-dependent conduct behavior reveals that electron transport of the graphene composite fibers belongs to hopping mechanism and the typical electrical conductivity reaches 4.59 × 10 3 S m -1 . These results demonstrated that the graphene composite fibers are promising for the next-generation flexible and wearable electronics.
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Kidney Disease and Diabetes - What You Need to Know
... of the spine. Their main job is to filter your blood to remove wastes that could damage ... healthy. Each kidney contains about one million tiny filters called nephrons. Inside each nephron are tiny blood ...
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A new carbon-rich phase (COPS) in Antarctic micrometeorites
NASA Technical Reports Server (NTRS)
Engrand, C.; Maurette, M.; Kurat, G.; Brandstatter, F.; Perreau, M.
1993-01-01
The contemporary flux of micrometeorites with sizes greater than 50 microns reaching the Earth's surface each year (about 20,000 tons/a) is much greater than the value of approximately 100 tons/a reported for conventional meteorites up to masses of approximately 10,000 tons. Moreover, on the average, Antarctic micrometeorites contain at least as much carbon as does Orgueil, the most C-rich meteorite. Micrometeorites are thus responsible for most of the carbon accreted by the Earth. In this paper we report SEM observations of a new C-rich 'dirty magnetite' phase observed as tiny inclusions in both melted and unmelted micrometeorites. This phase, which is enriched in C, O, P, S, Fe, frequently shows Ni contents in excess of 0.2 percent, strongly suggestive of an 'extraterrestrial' origin. We also discovered this 'COPS' phase in the fusion crust of Murchison. It appears likely that COPS is a product of meteoroid reprocessing during frictional heating in the Earth's atmosphere and/or its fast 'weathering' in the upper atmosphere. Upon 'catalyzed' hydrolysis this phase might have facilitated the functioning of micrometeorites as 'micro-chondritic-reactors' for the synthesis of prebiotic molecules on the early Earth.
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Proceedings of the Second Switch Tube Advanced Technology Meeting
NASA Astrophysics Data System (ADS)
Beavis, L. C.
1991-07-01
The Second Switch Tube Technology Review Meeting was held at EG&G Salem, MA, on February 21, 1991. This document is a compilation of the abstracts, viewgraphs and written materials supplied by the presenters from Allied Signal Kansas City Division, EG&G Salem and Sandia National Laboratories. It has not been reviewed nor edited in any way. Also included is an agenda of the meeting and a list of attendees. Covered topics include, Temperature of Uniformity Survey, Brazing Furnace Atmosphere Purity Studies, Creep of Cu Braze Materials and Area Seal Braze Joints, Characterization of the Screen Printing Process, Purity and Structures, Grain Growth and Thermal Treatment of KOVAR, Laser Weldability Testing of KOVAR, Decarburization -- Is It Required, Gross Impurities in KOVAR, Carbon Doping Desorption Studies Update, and MC3857 Sprytron Carbon Doping Matrix Evaluation.
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Thermal Stability of RP-2 for Hydrocarbon Boost Regenerative Cooling
NASA Technical Reports Server (NTRS)
Kleinhenz, Julie E.; Deans, Matthew C.; Stiegemeier, Benjamin R.; Psaras, Peter M.
2013-01-01
A series of tests were performed in the NASA Glenn Research Centers Heated Tube Facility to study the heat transfer and thermal stability behavior of RP-2 under conditions similar to those found in rocket engine cooling channels. It has long been known that hydrocarbon fuels, such as RP-2, can decompose at high temperature to form deposits (coke) which can adversely impact rocket engine cooling channel performance. The heated tube facility provides a simple means to study these effects. Using resistively heated copper tubes in a vacuum chamber, flowing RP-2 was heated to explore thermal effects at a range of test conditions. Wall temperature (850-1050F) and bulk fluid temperature (300-500F) were varied to define thermal decomposition and stability at each condition. Flow velocity and pressure were fixed at 75 fts and 1000 psia, respectively. Additionally, five different batches of RP-2 were tested at identical conditions to examine any thermal stability differences resulting from batch to batch compositional variation. Among these tests was one with a potential coke reducing additive known as 1,2,3,4-Tetrahydroquinoline (THQ). While copper tubes were used for the majority of tests, two exploratory tests were performed with a copper alloy known as GRCop-42. Each tube was instrumented with 15 thermocouples to examine the temperature profile, and carbon deposition at each thermocouple location was determined post-test in an oxidation furnace. In many tests, intermittent local temperature increases were observed visually and in the thermocouple data. These hot spots did not appear to correspond with a higher carbon deposition.
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76 FR 38613 - Initiation of Five-Year (“Sunset”) Review
Federal Register 2010, 2011, 2012, 2013, 2014
2011-07-01
.... Alloy Steel Pipe (3rd Review). A-580-809 731-TA-533 South Korea Circular Welded Non- David Goldberger, (202) 482-4136. Alloy Steel Pipe (3rd Review). A-489-501 731-TA-273 Turkey Welded Carbon Steel David Goldberger, (202) 482-4136. Pipe & Tube (3rd Review). C-489-502 701-TA-253 Turkey Welded Carbon Steel David...
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Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure receptacles. 173.302b Section 173.302b Transportation... cylinder. The use of UN tubes and MEGCs is not authorized. (e) Carbon monoxide, compressed UN 1016. Carbon...
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Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 2 2011-10-01 2011-10-01 false Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure receptacles. 173.302b Section 173.302b Transportation... cylinder. The use of UN tubes and MEGCs is not authorized. (e) Carbon monoxide, compressed UN 1016. Carbon...
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The aqueous electrochemistry of carbon-based surfaces-investigation by scanning tunneling microscopy
NASA Astrophysics Data System (ADS)
Mühl, T.; Myhra, S.
2007-04-01
Electro-oxidation of carbon-based materials will lead to conversion of the solid to CO2/CO at the anode, with H2 being produced at the cathode. Recent voltammetric investigations of carbon nano-tubes and single crystal graphite have shown that only edge sites and other defect sites are electrochemically active. Local oxidation of diamond-like carbon films (DLC) by an STM tip in moist air followed by imaging allows correlation of topographical change with electro-chemical conditions and surface reactivity. The results may have implications for lithographic processing of carbon surfaces, and may have relevance for electrochemical H2 production.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Han, Longtao; Krstic, Predrag; Kaganovich, Igor
Here we find that negative charges on an armchair single-walled carbon nanotube (SWCNT) can significantly enhance the migration of a carbon adatom on the external surfaces of SWCNTs, along the direction of the tube axis. Nanotube charging results in stronger binding of adatoms to SWCNTs and consequent longer lifetimes of adatoms before desorption, which in turn increases their migration distance several orders of magnitude. These results support the hypothesis of diffusion enhanced SWCNT growth in the volume of arc plasma. This process could enhance effective carbon flux to the metal catalyst.
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Targeted Delivery of Carbon Nanotubes to Cancer Cells
2009-09-01
Taylor S, Li HP, Fernando KAS, Qu LW, Wang W, Gu LR, Zhou B, Sun YP. Advances toward bioapplications of carbon nanotubes. J Mater Chem. 14: 527...respectively. For car- boxylated-CNTs and RFB4-coupled CNTs, 20 ll of the dispersion was spun cast on to freshly cleaved mica at 3500 rpm for 30 sec...Lin Y, Taylor S, Li HP, Fernando KAS, Qu LW, Wang W, Gu LR, Zhou B, Sun YP. Advances toward bioapplications of carbon nano- tubes. J Mater Chem
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Glycolysis regulates pollen tube polarity via Rho GTPase signaling
Chen, Wei; Gong, Pingping; Guo, Jingzhe; Li, Hui; Li, Ruizi; Xing, Weiman; Yang, Zhenbiao
2018-01-01
As a universal energy generation pathway utilizing carbon metabolism, glycolysis plays an important housekeeping role in all organisms. Pollen tubes expand rapidly via a mechanism of polarized growth, known as tip growth, to deliver sperm for fertilization. Here, we report a novel and surprising role of glycolysis in the regulation of growth polarity in Arabidopsis pollen tubes via impingement of Rho GTPase-dependent signaling. We identified a cytosolic phosphoglycerate kinase (pgkc-1) mutant with accelerated pollen germination and compromised pollen tube growth polarity. pgkc-1 mutation greatly diminished apical exocytic vesicular distribution of REN1 RopGAP (Rop GTPase activating protein), leading to ROP1 hyper-activation at the apical plasma membrane. Consequently, pgkc-1 pollen tubes contained higher amounts of exocytic vesicles and actin microfilaments in the apical region, and showed reduced sensitivity to Brefeldin A and Latrunculin B, respectively. While inhibition of mitochondrial respiration could not explain the pgkc-1 phenotype, the glycolytic activity is indeed required for PGKc function in pollen tubes. Moreover, the pgkc-1 pollen tube phenotype was mimicked by the inhibition of another glycolytic enzyme. These findings highlight an unconventional regulatory function for a housekeeping metabolic pathway in the spatial control of a fundamental cellular process. PMID:29702701
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NASA Astrophysics Data System (ADS)
Macphee, Andrew; Casey, Daniel; Clark, Daniel; Field, John; Haan, Steven; Hammel, Bruce; Kroll, Jeremy; Landen, Otto; Martinez, David; Milovich, Jose; Nikroo, Abbas; Rice, Neal; Robey, Harry; Smalyuk, Vladimir; Stadermann, Michael; Weber, Christopher; Lawrence Livermore National Laboratory Collaboration; Atomics Collaboration, General
2016-10-01
Features associated with the target support tent and deuterium-tritium fuel fill tube and support rods can seed hydrodynamic instabilities leading to degraded performance for inertial confinement fusion (ICF) experiments at the National Ignition Facility. We performed in-flight radiography of ICF capsules in the vicinity of the capsule support tent and fill tube surrogates to investigate instability growth associated with these features. For both plastic and high density carbon ablators, the shadow of the 10 μm diameter glass fill-tube cast by the x-ray spots on the hohlraum wall were observed to imprint radial instabilities around the fill tube/capsule interface. Similarly, instability growth was observed for the shadow cast by 12 μm diameter silicon carbide capsule support rods mounted orthogonal to the fill tube as a tent alternative for a plastic ablator. The orientation of the shadows is consistent with raytracing. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
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NASA Technical Reports Server (NTRS)
Kaul, A. B.; Megerian, K. G.; Baron, R. L.; Jennings, A. T.; Jang, D.; Greer, J. R.
2011-01-01
We have developed manufacturable approaches to form single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 micron deep trenches. These wafer-scale approaches were enabled by chemically amplified resists and inductively coupled Cryo-etchers to form the 3D nanoscale architectures. The tube growth was performed using dc plasmaenhanced chemical vapor deposition (PECVD), and the materials used for the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. The TEM analysis of our tubes revealed graphitic basal planes inclined to the central or fiber axis, with cone angles up to 30 deg. for the particular growth conditions used. In addition, bending tests performed using a custom nanoindentor, suggest that the tubes are well adhered to the Si substrate. Tube characteristics were also engineered to some extent, by adjusting growth parameters, such as Ni catalyst thickness, pressure and plasma power during growth.
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Tetracycline Resistance in the Subsurface of a Poultry Farm: Influence of Poultry Wastes
NASA Astrophysics Data System (ADS)
You, Y.; Ball, W. P.; Ward, M. J.; Hilpert, M.
2007-12-01
Concentrated animal feeding operations (CAFOs) are considered to be important man-made reservoir of antibiotic resistant bacteria. Using the electromagnetic induction (EMI) method of geophysical characterization, we measured the apparent subsurface electrical conductivity (ECa) at a CAFO site in order to assess the movement of pollutants associated with animal waste. The map of ECa and other available data suggest that (1) soil surrounding a poultry litter storage shed is contaminated by poultry waste, (2) a contamination plume in the subsurface emanates from that shed, and (3) the development of that plume is due to groundwater flow. We focused on understanding the spread of tetracycline resistance (Tc\\tiny R), because tetracycline is one of the most frequently used antibiotics in food animal production and therefore probably used at our field site. Microbiological experiments show the presence of Tc\\tiny R bacteria in the subsurface and indicate higher concentrations in the top soil than in the aquifer. Environmental DNA was extracted to identify CAFO- associated Tc\\tiny R genes and to explore a link between the presence of Tc\\tiny R and CAFO practices. A "shot-gun" cloning approach is under development to target the most prevalent Tc\\tiny R gene. This gene will be monitored in future experiments, in which we will study the transmission of Tc\\tiny R to naive E.~coli under selective pressure of Tc. Experimental results will be used to develop a mathematical/numerical model in order to describe the transmission process and to subsequently make estimates regarding the large-scale spread of antibiotic resistance.
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Ti(Ni,Cu) pseudobinary compounds as efficient negative electrodes for Ni-MH batteries
NASA Astrophysics Data System (ADS)
Emami, Hoda; Cuevas, Fermin; Latroche, Michel
2014-11-01
The effect of Ni by Cu substitution on the structural, solid-gas and electrochemical hydrogenation properties of TiNi has been investigated. Pseudo-binary TiNi1-xCux (x ≤ 0.5) compounds have been synthesized by induction melting. They crystallize in B2 structure above 350 K and either in B19‧ (x < 0.1) or B19 (0.2 ≤ x ≤ 0.5) at room temperature (RT). For all compounds, Pressure-Composition Isotherms at 423 K exhibit a single slopping plateau pressure within the range 10-3-1 MPa of hydrogen pressure revealing a metal to hydride transformation. Both the hydrogenation capacity and the hydride stability decrease with Cu-content. The hydrided pseudobinary compounds crystallize in the tetragonal S.G. I4/mmm structure as for TiNi hydride. The electrochemical discharge capacity increases with Cu content from 150 mAh g-1 for TiNi up to 300 mAh g-1 for TiNi0.8Cu0.2 and then decreases again for larger Cu amounts. Electrochemical isotherms and in-situ neutron diffraction measurements at RT demonstrate that such a capacity increase results from a metal to hydride phase transformation in which the hydride phase is destabilized by Cu substitution. The TiNi0.8Cu0.2 compound exhibits interesting cycling stability for 30 cycles and good high-rate capability at D/2 rate. This compound has promising electrochemical properties as compared to commercial LaNi5-type alloys with the advantage of being rare-earth metal free.
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Bismuth@US-tubes as a Potential Contrast Agent for X-ray Imaging Applications
Rivera, Eladio J.; Tran, Lesa A.; Hernández-Rivera, Mayra; Yoon, Diana; Mikos, Antonios G.; Rusakova, Irene A.; Cheong, Benjamin Y.; Cabreira-Hansen, Maria da Graça; Willerson, James T.; Perin, Emerson C.; Wilson, Lon J.
2013-01-01
The encapsulation of bismuth as BiOCl/Bi2O3 within ultra-short (ca. 50 nm) single-walled carbon nanocapsules (US-tubes) has been achieved. The Bi@US-tubes have been characterized by high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Bi@US-tubes have been used for intracellular labeling of pig bone marrow-derived mesenchymal stem cells (MSCs) to show high X-ray contrast in computed tomography (CT) cellular imaging for the first time. The relatively high contrast is achieved with low bismuth loading (2.66% by weight) within the US-tubes and without compromising cell viability. X-ray CT imaging of Bi@US-tubes-labeled MSCs showed a nearly two-fold increase in contrast enhancement when compared to unlabeled MSCs in a 100 kV CT clinical scanner. The CT signal enhancement from the Bi@US-tubes is 500 times greater than polymer-coated Bi2S3 nanoparticles and several-fold that of any clinical iodinated contrast agent (CA) at the same concentration. Our findings suggest that the Bi@US-tubes can be used as a potential new class of X-ray CT agent for stem cell labeling and possibly in vivo tracking. PMID:24288589
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Li, Qing; Xu, Ping; Gao, Wei; Ma, Shuguo; Zhang, Guoqi; Cao, Ruiguo; Cho, Jaephil; Wang, Hsing-Lin; Wu, Gang
2014-03-05
Nitrogen-doped graphene/graphene-tube nanocomposites are prepared by a hightemperature approach using a newly designed cage-containing metal-organic framework (MOF) to template nitrogen/carbon (dicyandiamide) and iron precursors. The resulting N-Fe-MOF catalysts universally exhibit high oxygen-reduction activity in acidic, alkaline, and non-aqueous electrolytes and superior cathode performance in Li-O2 batteries. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Field Emission of Thermally Grown Carbon Nanostructures on Silicon Carbide
2012-03-22
increased temperature, and (f) beginning formation of MWCNT [23] ......................15 Figure 11 – Comparison of XPS measurements (a) before heating...cathode material to heat and thermally breakdown. 3 Research on the ideal cathode has been going on for more than half a century. Dr. John R...proportional to the diameter of the tube with a value of 0.8 eV for a 1 nm diameter tube. Because MWCNTs are formed from layers of smaller CNTs, they
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Wu, Jianhua; Hagelberg, Frank
2013-06-03
The magnetic properties of axially confined, hydrogenated single-walled carbon nanotubes (SWCNTs) of the (n,0)-type with n=5-24 are systematically explored by density functional theory. Emphasis is placed on the relation between the ground-state magnetic moments of SWCNTs and zigzag graphene nanoribbons (ZGNRs). Comparison between the SWCNTs considered here and ZGNRs of equal length gives rise to two basic questions: 1) how does the nanotube curvature affect the antiferromagnetic order known to prevail for ZGNRs, and 2) to what extent do the magnetic moments localized at the SWCNT edges deviate from the zero-curvature limit of n/3μB ? In response to these questions, it is found that systems with n≥7 display preference for antiferromagnetic order at any length investigated, whereas for n=5, 6 the magnetic phase varies with tube length. Furthermore, elementary patterns are identified that describe the progression of the magnitude of the magnetic moment with n for the longest tubes explored in this work. The spin densities of the considered SWCNTs are analyzed as a function of the tube length L, with L ranging from 3 to 11 transpolyene rings for n≥7 and from 3 to 30 rings for n=5 and 6. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Galled by the Gallbladder?: Your Tiny, Hard-Working Digestive Organ
... Galled by the Gallbladder? Your Tiny, Hard-Working Digestive Organ En español Send us your comments Most ... among the most common and costly of all digestive system diseases. By some estimates, up to 20 ...
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Fabrication of Single, Vertically Aligned Carbon Nanotubes in 3D Nanoscale Architectures
NASA Technical Reports Server (NTRS)
Kaul, Anupama B.; Megerian, Krikor G.; Von Allmen, Paul A.; Baron, Richard L.
2010-01-01
Plasma-enhanced chemical vapor deposition (PECVD) and high-throughput manufacturing techniques for integrating single, aligned carbon nanotubes (CNTs) into novel 3D nanoscale architectures have been developed. First, the PECVD growth technique ensures excellent alignment of the tubes, since the tubes align in the direction of the electric field in the plasma as they are growing. Second, the tubes generated with this technique are all metallic, so their chirality is predetermined, which is important for electronic applications. Third, a wafer-scale manufacturing process was developed that is high-throughput and low-cost, and yet enables the integration of just single, aligned tubes with nanoscale 3D architectures with unprecedented placement accuracy and does not rely on e-beam lithography. Such techniques should lend themselves to the integration of PECVD grown tubes for applications ranging from interconnects, nanoelectromechanical systems (NEMS), sensors, bioprobes, or other 3D electronic devices. Chemically amplified polyhydroxystyrene-resin-based deep UV resists were used in conjunction with excimer laser-based (lambda = 248 nm) step-and-repeat lithography to form Ni catalyst dots = 300 nm in diameter that nucleated single, vertically aligned tubes with high yield using dc PECVD growth. This is the first time such chemically amplified resists have been used, resulting in the nucleation of single, vertically aligned tubes. In addition, novel 3D nanoscale architectures have been created using topdown techniques that integrate single, vertically aligned tubes. These were enabled by implementing techniques that use deep-UV chemically amplified resists for small-feature-size resolution; optical lithography units that allow unprecedented control over layer-to-layer registration; and ICP (inductively coupled plasma) etching techniques that result in near-vertical, high-aspect-ratio, 3D nanoscale architectures, in conjunction with the use of materials that are structurally and chemically compatible with the high-temperature synthesis of the PECVD-grown tubes. The techniques offer a wafer-scale process solution for integrating single PECVD-grown nanotubes into novel architectures that should accelerate their integration in 3D electronics in general. NASA can directly benefit from this technology for its extreme-environment planetary missions. Current Si transistors are inherently more susceptible to high radiation, and do not tolerate extremes in temperature. These novel 3D nanoscale architectures can form the basis for NEMS switches that are inherently less susceptible to radiation or to thermal extremes.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ono, Shota, E-mail: shota-o@gifu-u.ac.jp; Department of Physics, Graduate School of Engineering, Yokohama National University, Yokohama 240-8501; Tanikawa, Kousei
Revealing a universal relation between geometrical structures and electronic properties of capped carbon nanotubes (CNTs) is one of the current objectives in nanocarbon community. Here, we investigate the local curvature of capped CNTs and define the cap region by a crossover behavior of the curvature energy versus the number of carbon atoms integrated from the tip to the tube region. Clear correlations among the energy gap of the cap localized states, the curvature energy, the number of carbon atoms in the cap region, and the number of specific carbon clusters are observed. The present analysis opens the way to understandmore » the cap states.« less
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Low-temperature field ion microscopy of carbon nanotubes
NASA Astrophysics Data System (ADS)
Ksenofontov, V. A.; Gurin, V. A.; Gurin, I. V.; Kolosenko, V. V.; Mikhailovskij, I. M.; Sadanov, E. V.; Mazilova, T. I.; Velikodnaya, O. A.
2007-10-01
The methods of high-resolution field ion microscopy with sample cooling to liquid helium temperature are used in a study of the products of gas-phase catalytic pyrolysis of hydrocarbons in the form of graphitized fibers containing carbon nanotubes. Full atomic resolution of the end cap of closed carbon nanotubes is achieved for the first time. It is found that the atomic structure of the tops of the caps of subnanometer carbon tubes consists predominantly of hexagonal rings. A possible reason for the improvement of the resolution of field ion images of nanotubes upon deep cooling is discussed.
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Synthesis of highly phase pure (Bi, Pb)-Sr-Ca-Cu-O superconductor
Dorris, S.E.; Poeppel, R.B.; Prorok, B.C.; Lanagan, M.T.; Maroni, V.A.
1994-10-11
An article and method of manufacture of (Bi,Pb)-Sr-Ca-Cu-O superconductor are disclosed. The superconductor is manufactured by preparing a first powdered mixture of bismuth oxide, lead oxide, strontium carbonate, calcium carbonate and copper oxide. A second powdered mixture is then prepared of strontium carbonate, calcium carbonate and copper oxide. The mixtures are calcined separately with the two mixtures then combined. The resulting combined mixture is then subjected to a powder in tube deformation and thermal processing to produce a substantially phase pure (Bi,Pb)-Sr-Ca-Cu-O superconductor. 5 figs.
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NASA Astrophysics Data System (ADS)
Diano, P.; Muggeo, A.; Van Duysen, J. C.; Guttmann, M.
1989-12-01
Alloy 690 is used to replace Alloy 600 for the fabrication of tubes for steam generators of french pressurized water nuclear reactors. In order to reduce the dispersion in tensile properties observed for the first Alloy 690 industrial tubes, and which had already been noticed for Alloy 600, a joint research programme has been carried out by Electricité de France (Département Etude des Matériaux) and Valinox Montbard. The dispersion in the tensile properties of the first industrial Alloy 690 tubes for PWR steam generators arises from two main factors: - a grain size dispersion which is in particular controlled by the carbon content and by the final heat treatment, - differences in the degree of strain hardening induced by the straightening process with rollers. An improvement of the fabrication processes which have an influence on these two factors has allowed to reduce considerably the dispersion of the tensile properties of the more recent series of tubes.
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Smith, Kirk R; McCracken, John P; Thompson, Lisa; Edwards, Rufus; Shields, Kyra N; Canuz, Eduardo; Bruce, Nigel
2010-07-01
During the first randomized intervention trial (RESPIRE: Randomized Exposure Study of Pollution Indoors and Respiratory Effects) in air pollution epidemiology, we pioneered application of passive carbon monoxide (CO) diffusion tubes to measure long-term personal exposures to woodsmoke. Here we report on the protocols and validations of the method, trends in personal exposure for mothers and their young children, and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations. Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0-18 months of age and 532 mothers aged 15-55 years and area samples in a subsample of 77 kitchens, in households randomized into control and intervention groups. Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO, and regression calibration was used to reduce this bias. Before stove introduction, the baseline arithmetic (geometric) mean 48-h child (n=270), mother (n=529) and kitchen (n=65) levels were, respectively, 3.4 (2.8), 3.4 (2.8) and 10.2 (8.4) p.p.m. The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period: kitchen levels: -90%; mothers: -61%; and children: -52% in geometric means. No significant deterioration in stove effect was observed over the 18 months of surveillance. The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes, measurement error reduction through instrument calibration, and a randomized, longitudinal study design. These results from the first randomized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants.
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SMITH, KIRK R.; McCRACKEN, JOHN P.; THOMPSON, LISA; EDWARDS, RUFUS; SHIELDS, KYRA N.; CANUZ, EDUARDO; BRUCE, NIGEL
2015-01-01
During the first randomized intervention trial (RESPIRE: Randomized Exposure Study of Pollution Indoors and Respiratory Effects) in air pollution epidemiology, we pioneered application of passive carbon monoxide (CO) diffusion tubes to measure long-term personal exposures to woodsmoke. Here we report on the protocols and validations of the method, trends in personal exposure for mothers and their young children, and the efficacy of the introduced improved chimney stove in reducing personal exposures and kitchen concentrations. Passive diffusion tubes originally developed for industrial hygiene applications were deployed on a quarterly basis to measure 48-hour integrated personal carbon monoxide exposures among 515 children 0–18 months of age and 532 mothers aged 15–55 years and area samples in a subsample of 77 kitchens, in households randomized into control and intervention groups. Instrument comparisons among types of passive diffusion tubes and against a continuous electrochemical CO monitor indicated that tubes responded nonlinearly to CO, and regression calibration was used to reduce this bias. Before stove introduction, the baseline arithmetic (geometric) mean 48-h child (n=270), mother (n=529) and kitchen (n=65) levels were, respectively, 3.4 (2.8), 3.4 (2.8) and 10.2 (8.4) p.p.m. The between-group analysis of the 3355 post-baseline measurements found CO levels to be significantly lower among the intervention group during the trial period: kitchen levels: −90%; mothers: −61%; and children: −52% in geometric means. No significant deterioration in stove effect was observed over the 18 months of surveillance. The reliability of these findings is strengthened by the large sample size made feasible by these unobtrusive and inexpensive tubes, measurement error reduction through instrument calibration, and a randomized, longitudinal study design. These results from the first randomized trial of improved household energy technology in a developing country and demonstrate that a simple chimney stove can substantially reduce chronic exposures to harmful indoor air pollutants among women and infants. PMID:19536077
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Phase separated membrane bioreactor: Results from model system studies
NASA Astrophysics Data System (ADS)
Petersen, G. R.; Seshan, P. K.; Dunlop, E. H.
The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestial simulation.
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Phase separated membrane bioreactor - Results from model system studies
NASA Technical Reports Server (NTRS)
Petersen, G. R.; Seshan, P. K.; Dunlop, E. H.
1989-01-01
The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestrial simulation.
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Model system studies with a phase separated membrane bioreactor
NASA Technical Reports Server (NTRS)
Petersen, G. R.; Seshan, P. K.; Dunlop, Eric H.
1989-01-01
The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestial simulation.
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Capillary-tube-based extension of thermoacoustic theory for a random medium
NASA Astrophysics Data System (ADS)
Roh, Heui-Seol; Raspet, Richard; Bass, Henry E.
2005-09-01
Thermoacoustic theory for a single capillary tube is extended to random bulk medium on the basis of capillary tubes. The characteristics of the porous stack inside the resonator such as the tortuosity, dynamic shape factor, and porosity are introduced for the extension of wave equation by following Attenborough's approach. Separation of the dynamic shape factor for the viscous and thermal effect is adopted and scaling using the dynamic shape factor and tortuosity factor is demonstrated. The theoretical and experimental comparison of thermoviscous functions in reticulated vitreous carbon (RVC) and aluminum foam shows reasonable agreement. The extension is useful for investigations of the properties of a stack with arbitrary shapes of non-parallel pores.
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Matsumura, H; Tanoue, N; Yanagida, H; Atsuta, M; Koike, M; Yoneyama, T
2003-06-01
The purpose of the current study was to evaluate the bonding characteristics of super-elastic titanium-nickel (Ti-Ni) alloy castings. Disk specimens were cast from a Ti-Ni alloy (Ti-50.85Ni mol%) using an arc centrifugal casting machine. High-purity titanium and nickel specimens were also prepared as experimental references. The specimens were air-abraded with alumina, and bonded with an adhesive resin (Super-Bond C & B). A metal conditioner containing a phosphate monomer (Cesead II Opaque Primer) was also used for priming the specimens. Post-thermocycling average bond strengths (MPa) of the primed groups were 41.5 for Ti-Ni, 30.4 for Ti and 19.5 for Ni, whereas those of the unprimed groups were 21.6 for Ti, 19.3 for Ti-Ni and 9.3 for Ni. Application of the phosphate conditioner elevated the bond strengths of all alloy/metals (P < 0.05). X-ray fluorescence analysis revealed that nickel was attached to the debonded resin surface of the resin-to-nickel bonded specimen, indicating that corrosion of high-purity nickel occurred at the resin-nickel interface. Durable bonding to super-elastic Ti-Ni alloy castings can be achieved with a combination of a phosphate metal conditioner and a tri-n-butylborane-initiated adhesive resin.
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Jung, Eui-Hyun; Park, Yong-Jin
2008-01-01
In recent years, a few protocol bridge research projects have been announced to enable a seamless integration of Wireless Sensor Networks (WSNs) with the TCP/IP network. These studies have ensured the transparent end-to-end communication between two network sides in the node-centric manner. Researchers expect this integration will trigger the development of various application domains. However, prior research projects have not fully explored some essential features for WSNs, especially the reusability of sensing data and the data-centric communication. To resolve these issues, we suggested a new protocol bridge system named TinyONet. In TinyONet, virtual sensors play roles as virtual counterparts of physical sensors and they dynamically group to make a functional entity, Slice. Instead of direct interaction with individual physical sensors, each sensor application uses its own WSN service provided by Slices. If a new kind of service is required in TinyONet, the corresponding function can be dynamically added at runtime. Beside the data-centric communication, it also supports the node-centric communication and the synchronous access. In order to show the effectiveness of the system, we implemented TinyONet on an embedded Linux machine and evaluated it with several experimental scenarios. PMID:27873968
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Colorimetric carbon dioxide detector to determine accidental tracheal feeding tube placement.
Howes, Daniel W; Shelley, Eric S; Pickett, William
2005-04-01
To determine the accuracy of colorimetric CO2 detection compared to the reference standard two-step radiological confirmation of feeding tube position. A prospective study was conducted with patients presenting to a 21-bed medical-surgical intensive care unit. An adapter was developed using an endotracheal tube adapter to connect a colorimetric CO2 detector to a feeding tube in an airtight manner. In part I of the study a feeding tube connected to the colorimeter was inserted into the endotracheal tubes of ten ventilated patients to test the device's ability to detect tracheal placement. In part II patients undergoing feeding tube insertion had tube position confirmed with the colorimeter as well as the reference standard two-step x-ray. In phase I the colorimeter correctly identified tracheal placement in all ten patients. In phase II 93/100 procedures ultimately were eligible; the colorimeter had a sensitivity of 0.88 (95% confidence interval: 0.65-1.00) and specificity of 0.99 (0.97-1.00). The device missed one of the eight tracheal placements. Agreement between the colorimeter and two-step x-ray interpretations was excellent (Kappa 0.86; standard error 0.10). We describe a novel, convenient method to confirm esophageal feeding tube placement. The device is easily assembled and inexpensive, but should not be reused. Colorimetric determination of tracheal feeding tube placement with this device has excellent agreement with the reference standard two-step radiological technique.