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Sample records for situ processed mgb

  1. Tellurium addition as a solution to improve compactness of ex-situ processed MgB2-SiC superconducting tapes

    NASA Astrophysics Data System (ADS)

    Sandu, V.; Aldica, G.; Popa, S.; Enculescu, Monica; Badica, P.

    2016-06-01

    Ex-situ spark plasma sintering (SPS) was used to obtain dense MgB2-based tapes in a Fe sheath with the starting composition (MgB2)0.975 + (SiC)0.025 + Te0.01. Prior to the SPS procedure of tape formation, the samples were submitted to a series of cold working processes typical for the powder-in-tube technique. The tapes were compared with optimal doped bulk samples (having the same starting composition) and a pristine MgB2 tape. The morphology of the composite samples, the phase structure of both the core and the inner face of the metallic sheath shows the formation of a plethora of traces as a result of interaction between MgB2, additives, and the Fe sheath. Important critical parameters, like critical current density and the irreversibility field, show that there is a field and temperature range where the SiC and Te-added tapes display better critical parameters comparative to either pristine MgB2 tapes in the Fe sheath or SiC and Te doped MgB2 bulk samples.

  2. Development of ex situ processed MgB 2 wires and their applications to magnets

    NASA Astrophysics Data System (ADS)

    Braccini, Valeria; Nardelli, Davide; Penco, Roberto; Grasso, Giovanni

    2007-06-01

    In spite of the relatively short time dedicated to the development of magnesium diboride conductors since its discovery in early 2001, a substantial improvement was soon achieved in their manufacture and use. Unlike many others HTS and LTS materials, the MgB 2 conductor processing is more open to a number of improvements and modifications that help in making it more attractive for several DC and AC applications. Many kilometres of conductors were already produced throughout the world and it is now possible to start seriously thinking about a systematic industrial production of this material, as it is already possible to purchase it in reasonable lengths on the free market. These remarkable lengths of conductor were also wound in coils and their performance continuously improved in the past years. Here we will present a review of the recent results and a perspective for the future development of this “new” superconductor, starting from the optimisation of the precursor powders needed to improve the magnetic field behaviour of the tapes, to the conductor development, i.e. the production of multifilamentary Cu-stabilized tapes in lengths up to 1.78 km, to the realization of the first large-scale application devices such as MRI magnets and fault current limiters.

  3. Effect of temperature and concentration of solution in chemical treatment for MgB 2 powder on the Jc- B property of ex situ processed MgB 2 superconducting tapes

    NASA Astrophysics Data System (ADS)

    Fujii, H.; Ozawa, K.

    2010-03-01

    MgB 2 tapes were fabricated through an ex situ process in a powder-in-tube (PIT) technique using powders treated at elevated temperatures in benzene solutions of benzoic acid with various concentrations. The amount of carbon substitution in MgB 2 in heat-treated tapes with treatment at the boiling points (BPs) of the solutions is smaller than that at room temperature (RT). This carbon substitution improves the Jc property in the high-field region. For RT treatment, the Jc property is improved with increasing the solution concentration. In contrast, the Jc property is deteriorated with increasing the concentration for BP treatment. On the other hand, treatment with pure solvent does not bring about the Jc enhancement and carbon substitution at all at both RT and the BPs. This suggests that acidity essential for the dissolution of MgO layers attached to the surface of MgB 2 is required for carbon substitution. The BP treatment enhances the acting of the acidity and possibly inflicts damage on MgB 2 itself.

  4. Properties of in situ made MgB2 in Nb or Ti sheath

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Kopera, L.; Melišek, T.; Rosová, A.; Dobročka, E.

    2013-02-01

    Pure Nb and Ti have been used as sheath materials for MgB2 wires examined experimentally. The reason for this research is to compare the effects of these metallic sheaths on the basic properties of MgB2 superconductor. Single-core SiC doped MgB2 wires with Nb and/or Ti sheaths have been made by a powder-in-tube in situ process. Different transport currents, phase compositions and grain connectivity were observed for Nb- and Ti sheathed MgB2 heat treated at temperatures 650-850 °C/30 min. It was found that the critical current density of MgB2/Nb annealed above 700 °C rapidly decreases, while Jc of MgB2/Ti is systematically increasing with temperature. This is explained by the positive role of Ti absorbing impurities from the MgB2 core and by the negative effect of boron diffusion into Nb, reducing the quantity and worsening the quality of the MgB2 core. The obtained results show clearly that a Ti sheath offers the application of higher heat treatment temperatures (above 700 °C) and consequently the achievement of higher critical current densities in comparison to MgB2/Nb.

  5. In situ epitaxial MgB2 thin films for superconducting electronics.

    PubMed

    Zeng, Xianghui; Pogrebnyakov, Alexej V; Kotcharov, Armen; Jones, James E; Xi, X X; Lysczek, Eric M; Redwing, Joan M; Xu, Shengyong; Li, Qi; Lettieri, James; Schlom, Darrell G; Tian, Wei; Pan, Xiaoqing; Liu, Zi-Kui

    2002-09-01

    The newly discovered 39-K superconductor MgB2 holds great promise for superconducting electronics. Like the conventional superconductor Nb, MgB2 is a phonon-mediated superconductor, with a relatively long coherence length. These properties make the prospect of fabricating reproducible uniform Josephson junctions, the fundamental element of superconducting circuits, much more favourable for MgB2 than for high-temperature superconductors. The higher transition temperature and larger energy gap of MgB2 promise higher operating temperatures and potentially higher speeds than Nb-based integrated circuits. However, success in MgB2 Josephson junctions has been limited because of the lack of an adequate thin-film technology. Because a superconducting integrated circuit uses a multilayer of superconducting, insulating and resistive films, an in situ process in which MgB2 is formed directly on the substrate is desirable. Here we show that this can be achieved by hybrid physical-chemical vapour deposition. The epitaxially grown MgB2 films show a high transition temperature and low resistivity, comparable to the best bulk samples, and their surfaces are smooth. This advance removes a major barrier for superconducting electronics using MgB2.

  6. The critical parameters in in-situ MgB2 wires and tapes with ex-situ MgB2 barrier after hot isostatic pressure, cold drawing, cold rolling and doping

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A. J.; Häßler, W.; Nenkov, K.; Rindfleisch, M. A.; Żuchowska, E.; Gajda, G.; Czujko, T.; Cetner, T.; Hossain, M. S. A.

    2015-05-01

    MgB2 precursor wires were prepared using powder in tube technique by Institute of High Pressure PAS in Warsaw. All samples were annealed under isostatic pressure generated by liquid Argon in the range from 0.3 GPa to 1 GPa. In this paper, we show the effects of different processing routes, namely, cold drawing (CD), cold rolling (CR), hot isostatic pressure (HIP) and doping on critical current density (Jc), pinning force (Fp), irreversible magnetic-field (Birr), critical temperature (Tc), n value, and dominant pinning mechanism in MgB2/Fe wires with ex situ MgB2 barrier. The results show that medium pressures (˜0.35 GPa) lead to high Jc in low and medium magnetic fields (0 T - 9 T). On the other hand, higher pressures (˜1 GPa) lead to enhanced Jc in high magnetic fields (above 9 T). Transport measurements show that CD, CR, and HIP have small effects on Birr and Tc, but CD, CR, HIP, and doping enhance Jc and Fp in in situ MgB2 wires with ex situ MgB2 barrier. Transport measurements on in situ undoped MgB2 wire with ex situ MgB2 barrier yield a Jc of about 100 A/mm2 at 4.2 K in 6 T, at 10 K in 4 T and at 20 K in 2 T. The results also show that cold drawing causes increase of n value.

  7. Comparison of critical current density in SiC-doped in situ MgB2 coils and straight wire samples processed by HIP

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A.; Cetner, T.; Małecka, M.; Presz, A.; Rindfleisch, M.; Tomsic, M.; Thong, C. J.; Surdacki, P.

    2013-11-01

    Unreacted MgB2 wires fabricated from SiC-doped precursor material by Hyper Tech Research, Inc. have been used to make small-diameter (14 mm) superconducting coils. All coils made of 500 mm length wires were subjected to hot isostatic pressure (HIP) treatment. The critical current density (Jc) parameters of coils were compared to straight samples characteristics. Both types of samples have been measured in perpendicular magnetic field configuration for Jc and pinning force density (Fp) evaluation. No significant Jc difference between the long wires on coils and straight wires was found. These results suggest that the critical current (Ic) for coils can be determined for straight samples (25 mm). SEM analysis indicated that a small diameter of the coil does not influence the structure of in situ MgB2 wire.

  8. Hot Extrusion of Ex-Situ MgB2 Powder

    NASA Astrophysics Data System (ADS)

    Nachtrab, William T.; Rudziak, Mark K.; Wong, Terence

    2008-03-01

    We investigated the fabrication of ex-situ processed MgB2 round wire by hot extrusion. Composite ex-situ MgB2 monocore billets were fabricated with a composite sheath consisting of either an AISI 304 or AISI 430 stainless steel clad with copper. The stainless steel was intended to serve as reinforcement for the powder core and maintain mechanical compatibility between the MgB2 core and the copper cladding. The composite billets were extruded at temperatures between 593 and 900 °C at a reduction ratio of 5.2 (81% RA). The billets having the 304 SS barrier cracked during extrusion, while the billets with 430 SS were successfully extruded. Several additional monocore billets with 430 SS/Cu sheath were extruded at 650 °C and reduction ratio of 5.0 (80% RA). The extruded rods were cold drawn, restacked in a copper tube in an 18 filament array, and subsequently cold drawn to 2 mm diameter. A 61 filament restack billet was also assembled and hot extruded at 538 °C and R = 5.0. The results demonstrate that hot extrusion has the potential to be a viable method for fabricating multifilament round MgB2 wire.

  9. Self-sintering-assisted high intergranular connectivity in ball-milled ex situ MgB2 bulks

    NASA Astrophysics Data System (ADS)

    Mizutani, Shunsuke; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ogino, Hiraku; Kishio, Kohji

    2014-11-01

    To understand the mechanisms leading to higher intergranular connectivity in polycrystalline ex situ MgB2 prepared using a pressure-less self-sintering technique, the influence of the initial particle size of the MgB2 powder was investigated. MgB2 bulks sintered at 900 °C for 24 h using ball-milled powders exhibited a network structure with both qualitatively and quantitatively improved intergranular couplings. The connectivity calculated using normal-state transport measurements reached a high value of ˜40%, which is comparable to that of MgB2 bulks fabricated via Mg diffusion or high-pressure-assisted processes. Moreover, the sintering time required to achieve a reasonably high connectivity of 25-30% was less than 1 h. Notably, microstructural analyses confirmed the formation of intergranular necks and grain boundaries during the early stage of sintering. These results suggested self-sintering of the ball-milled MgB2 bulks proceeded much more rapidly than those sintered using an MgB2 powder without ball-milling. Increased intergranular contact points and decreased gap length between grains in green compact are assumed to be the origins for the stimulated self-sintering and corresponding increase in the electrical connectivity.

  10. In situ Pulsed Laser Deposition of C-Axis Oriented MgB2 Films and Their Characterization

    NASA Technical Reports Server (NTRS)

    Shinde, Sanjay; Lakew, Brook; Ogale, S. B.; Kulkarni, V. N.; Kale, S. N.; Venkatesan, T.

    2004-01-01

    The recent discovery of an intermetallic superconductor MgB2 has renewed interest in the area of superconductivity not only because of fundamental understanding of superconductivity but also due to its potential applicability in devices such as thermal detectors. Considerable amount of research has been devoted to obtain MgB2 films by an all in situ growth technique. We have grown MgB2 thin films by an all in situ pulsed laser deposition process from pure B and Mg targets. Ultrathin layers of B and Mg were deposited in a multilayer configuration. Hundreds of such Mg-B bilayers with a capping Mg layer on the top were deposited on sapphire substrate. These depositions were done in high vacuum (approx. 10(exp -7) Torr) and at room temperature. After deposition, such a configuration was annealed at high temperature for a short time in a forming gas (4% H2 in Ar). The best films, obtained by this procedure, showed superconducting transition temperature approx. 30 K. These films have been characterized by x-ray diffraction, Rutherford Backscattering Spectrometry, AC susceptibility-, resistivity- (with and without magnetic field) and 1/f noise-measurements. The physical properties of these films will be presented and discussed.

  11. Fabrication and superconducting properties of internal Mg diffusion processed MgB2 wires using MgB4 precursors

    NASA Astrophysics Data System (ADS)

    Xu, Da; Wang, Dongliang; Yao, Chao; Zhang, Xianping; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-10-01

    Monofilament MgB2/Nb/Monel wires were fabricated using three different MgB4 precursors by an internal Mg diffusion (IMD) process. The wire geometry and heat-treatment conditions were optimized in order to improve the critical current density (J c) of the MgB2 wire. The influences of the quality of MgB4 powders, such as the particle size and MgO impurity, on the microstructure and superconducting properties of the wires were discussed. Although there were small amounts of voids, unreacted MgB4 particles and MgO impurity existed in the superconducting layers, and the transport layer J c of the wire with the MgB4 precursor reached 3.0 × 104 A cm-2 at 4.2 K and 10 T, which was comparable to that of IMD-processed wires fabricated using boron precursors. Both the non-barrier J c and engineering J c of MgB2 wire made using a MgB4 precursor were enhanced due to the improved grain connectivity and the enlarged fill factor.

  12. Electromagnetic properties and microstructures of in situ MgB2 wires made from three types of boron powders

    NASA Astrophysics Data System (ADS)

    Kodama, Motomune; Kotaki, Hiroshi; Yamamoto, Hiroyuki; Iwane, Tomohiro; Tanaka, Kazuhide; Tanaka, Hideki; Okishiro, Kenji; Okamoto, Kazutaka; Nishijima, Gen; Matsumoto, Akiyoshi; Kumakura, Hiroaki; Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Kishio, Kohji

    2016-10-01

    In powder-in-tube processed MgB2 wires, the choice of boron powder as a starting material crucially affects their performance. In this paper, we prepared in situ MgB2 wires from three types of boron powders in various heat-treatment conditions and investigated their electromagnetic properties and microstructures. Their critical current density, J c, varied over a wide range from sample to sample. The difference in J c is understood to be caused by the effect of changes in the electrical connectivity, K, and intrinsic residual resistivity, ρ 0. Here, K represents the effective cross-sectional area for current, and ρ 0 reflects the degree of the charge carrier scattering caused by lattice defects. It was found that the use of boron powder with a large specific surface area leads to a large degree of lattice defects in MgB2 grains and enhances ρ 0, resulting in improving J c. The boron powder produced by thermal decomposition of B2H6 has a large specific surface area. Hence, this boron powder is the most suitable as a starting material for MgB2. Meanwhile, dry pulverization of low-cost boron powder, which is largely produced by active-metal reduction of B2O3, is also effective to increase its specific surface area without introducing impurities, resulting in the enhancement of J c in the entire magnetic field region. This finding broadens the choice of boron powder and contributes to realizing superconducting applications with excellent balance between performance and cost.

  13. Fast creation of dense MgB2 phase in wires made by IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kopera, L.; Kulich, M.

    2016-10-01

    Single-core MgB2 wires have been made by internal magnesium diffusion (IMD) into boron process. Heat treatments were performed at variable periods (4-90 min) for two adjusted temperatures 635 °C and 650 °C, with an overshoot of ≈20 °C after 5 min. Critical currents of differently treated MgB2/Ti/GlidCop wires have been measured and related with the MgB2 layers. The fast creation MgB2 compound has been observed after 8 min annealing at both temperatures and showing the critical current maxima. The less uniform MgB2 containing cracks was created for longer annealing periods (≥10 min), which resulted in lowered critical currents and worsened thermal stability. The fast creation of dense MgB2 allows it to utilize a continual and short heat treatment process for high current density wires made by IMD.

  14. Kinetic analysis of MgB2 layer formation in advanced internal magnesium infiltration (AIMI) processed MgB2 wires

    PubMed Central

    Li, G. Z.; Sumption, M. D.; Collings, E. W.

    2015-01-01

    Significantly enhanced critical current density (Jc) for MgB2 superconducting wires can be obtained following the advanced internal Mg infiltration (AIMI) route. But unless suitable precautions are taken, the AIMI-processed MgB2 wires will exhibit incomplete MgB2 layer formation, i.e. reduced superconductor core size and hence suppressed current-carrying capability. Microstructural characterization of AIMI MgB2 wires before and after the heat treatment reveals that the reaction mechanism changes from a “Mg infiltration-reaction” at the beginning of the heat treatment to a “Mg diffusion-reaction” once a dense MgB2 layer is formed. A drastic drop in the Mg transport rate from infiltration to diffusion causes the termination of the MgB2 core growth. To quantify this process, a two-stage kinetic model is built to describe the MgB2 layer formation and growth. The derived kinetic model and the associated experimental observations indicate that fully reacted AIMI-processed MgB2 wires can be achieved following the optimization of B particle size, B powder packing density, MgB2 reaction activation energy and its response to the additions of dopants. PMID:26973431

  15. A new approach to a superconducting joining process for carbon-doped MgB2 conductor

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; Maeda, Minoru; Shahabuddin, Mohammed; Yanmaz, Ekrem; Pradhan, Subrata; Tomsic, Mike; Choi, Seyong; Kim, Jung Ho

    2016-09-01

    We report a new approach to a superconducting joining process for unreacted in situ carbon (C)-doped magnesium diboride (MgB2) wires. To operate a magnetic resonance imaging (MRI) magnet in the persistent mode, the superconducting joints between two conductors are as critical as the other key components. In addition, a stable and reliable joining process enables the superconducting magnet to operate without an external power supply. However, joint results using unreacted in situ C-doped MgB2 wires, which are used for high-field operation, have been limited, and only very poor performance has been obtained. By controlling the pressure inside a joint part, in this study, we successfully obtained current carrying retention in the joint of up to 72% compared to wire without a joint. The closed-circuit resistance of our closed-loop coil was less than 1.8 × 10-13 Ω at 16.7 ± 4.7 K, as measured by the field-decay measurement method. These results indicate that MgB2 has a promising future in MRI application.

  16. A new approach to a superconducting joining process for carbon-doped MgB2 conductor

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; Maeda, Minoru; Shahabuddin, Mohammed; Yanmaz, Ekrem; Pradhan, Subrata; Tomsic, Mike; Choi, Seyong; Kim, Jung Ho

    2016-09-01

    We report a new approach to a superconducting joining process for unreacted in situ carbon (C)-doped magnesium diboride (MgB2) wires. To operate a magnetic resonance imaging (MRI) magnet in the persistent mode, the superconducting joints between two conductors are as critical as the other key components. In addition, a stable and reliable joining process enables the superconducting magnet to operate without an external power supply. However, joint results using unreacted in situ C-doped MgB2 wires, which are used for high-field operation, have been limited, and only very poor performance has been obtained. By controlling the pressure inside a joint part, in this study, we successfully obtained current carrying retention in the joint of up to 72% compared to wire without a joint. The closed-circuit resistance of our closed-loop coil was less than 1.8 × 10‑13 Ω at 16.7 ± 4.7 K, as measured by the field-decay measurement method. These results indicate that MgB2 has a promising future in MRI application.

  17. Manufacturing process influence on superconducting properties of MgB2 wires prepared using laboratory made boron

    NASA Astrophysics Data System (ADS)

    Bovone, Gianmarco; Matera, Davide; Bernini, Cristina; Magi, Emanuele; Vignolo, Maurizio

    2015-06-01

    Here we report a systematic study of the superconductive properties of mono-filamentary MgB2-based wires, manufactured with four different techniques. A detailed comparison of the influence of manufacturing technique and final heat treatment on superconducting properties has been given. The boron used was synthesized in laboratory following magnesiothermic reduction of boron oxide, purified thanks to several acid leaching and heat treated at high temperature, to enhance crystalline degree and remove impurities. MgB2 conductors were manufactured using the same B precursor through four different techniques (ex situ, in situ, the MgB4 or ‘mixed’ technique (half ex situ and half in situ), and reactive liquid infiltration (Rli)). Transport critical current density was measured on the best wire for each technique, considering the literature data in order to identify the corresponding best final heat treatment. Magnetic critical current density and critical temperature were investigated at different synthesis/sintering temperatures in order to evaluate their dependence to the applied final heat treatment and the data were compared. Critical current density was evaluated on short wire pieces by magnetic measurement at 5 K in a MPMS 5.5 T Quantum Design SQUID, while critical temperature was measured with a four probe system by drop of resistivity during the cooling process of the sample in a liquid helium dewar. A detailed morphological analysis is given, with void percentage evaluation and analysis of elemental Mg diffusion across the transversal cross section. X-ray diffraction was performed on MgB2 powder extracted removing each metal sheath, in order to investigate the influence of manufacturing process on the MgB2 phase. This study shows that despite the presence of a wide void within the superconducting core (due to the Mg diffusion) in the Rli sample, this manufacturing technique allows wires with higher Jc (105 A cm-2 at 3 T when heat treatment at 700 °C is

  18. Synthesis of MgB 2 film by electrochemical process

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiroshi; Kuramochi, Takashi; Furuya, Yudai; Oike, Hiromi; Kato, Tadashi; Hoshi, Kazushi

    2008-07-01

    In order to synthesize MgB2 films, electrolysis is performed in an electrolyte comprising a fused mixture of B2O3, KCl and MgCl2 in a molar ratio of B2O3:KCl:MgCl2 = x:3.5:5. The results of the Meissner effects and X-ray diffraction measurements indicate the formation of MgB2 films on graphite and Si substrates. The superconducting critical temperature depends on both the synthesis temperature of the electrolysis and the amount of B2O3 in the electrolyte.

  19. Bending strain tolerance of MgB2 superconducting wires

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Melišek, T.; Kulich, M.; Kopera, L.

    2016-04-01

    This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. I c-bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.

  20. Fabrication of MgB2 superconducting wires with a hybrid method combining internal-Mg-diffusion and powder-in-tube processes

    NASA Astrophysics Data System (ADS)

    Ye, ShuJun; Matsumoto, Akiyoshi; Togano, Kazumasa; Zhang, YunChao; Ohmura, Takahito; Kumakura, Hiroaki

    2014-05-01

    We have previously reported that the addition of Mg powder to the B powder layer (B layer) of internal-Mg-diffusion (IMD)-processed MgB2 wires can decrease the amount of unreacted B particles, and hence increase the critical current density (Jc). As the amount of Mg powder is increased, the diameter of the central Mg rod must be reduced in order to maintain an overall Mg:B molar ratio of 1:2, corresponding to stoichiometric MgB2. If this ratio is achieved by the Mg powder alone, then the required diameter of the Mg rod is zero, which means that the IMD process becomes the powder-in-tube (PIT) process. A hybrid process intermediate between the IMD and PIT processes is proposed as a new approach for fabricating MgB2 wires. In the present study, the critical current and microstructure of MgB2 wires fabricated using this method are investigated. It is found that the method yields a higher engineering critical current density (Je, = Jc × MgB2 area fraction, where the MgB2 area fraction corresponds to the ratio of the MgB2 cross-sectional area to the total cross-sectional area of the wire) than that for either the IMD or the PIT method. Compared with the IMD method, the MgB2 layer thickness (the thickness of the MgB2 layer in the transverse cross section) is increased and the diameter of the central hole is decreased, thus increasing the MgB2 area fraction The proposed method also achieves a much higher MgB2 layer density, and thus a much higher Jc, than is possible using the PIT method. The combination of these factors leads to the enhanced Je value of MgB2 wires.

  1. MgB2 wires with Ti and NbTi barrier made by IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Kulich, M.; Melišek, T.; Kováč, J.; Kopera, L.

    2016-10-01

    MgB2 wires with Ti and NbTi barriers have been made by internal magnesium diffusion (IMD) into boron process. Critical currents, strain tolerances and AC loss of wires with Ti and NbTi barriers have been compared. It was shown that worse uniformity of NbTi barrier affects the creation of regular MgB2 layer and consequently influences (reduces) also the current densities. Positive effects of NbTi barrier are in improved strain tolerance and reduced coupling losses. The maximum AC loss of not twisted wire with Ti barrier is measured at frequency 9 Hz, but it is shifted up to 60 Hz for NbTi due to considerably increased barrier resistance at 20 K.

  2. Effect of boron particle size on microstructure and superconducting properties of in-situ Cu addition MgB2 multifilamentary wire

    NASA Astrophysics Data System (ADS)

    Hishinuma, Y.; Kikuchi, A.; Shimada, Y.; Hata, S.; Takeuchi, T.; Yamada, S.; Sagara, A.

    2014-05-01

    In previous studies, the secondary (impurity and non-reactive) phase and voids were observed in MgB2 matrix after the heat treatment, and then these are the lowering factors of critical current density (Jc) property. In order to improve Jc property by microstructure control of MgB2 matrix, the fine elemental boron powder as the raw material was carried out using the high-speed vibrated milling with tungsten carbide (WC) jar. The average particle size of metal boron powder was decreased from 1.14 μm to 0.20 μm by the high-speed vibrated milling. The various fine particle boron powders as the function of milling time were also prepared, and in-situ Cu addition MgB2 multifilamentary wires using these fine boron powders were fabricated. Critical transition temperature (Tc) value of Cu addition MgB2 wire using fine boron powder obtained to about 37 K. No change of the Tc property by the different particle sized boron powders was confirmed. In this paper, the comparisons of microstructure and superconducting properties between the different boron particle sizes were investigated.

  3. In Situ Processing.

    ERIC Educational Resources Information Center

    Edgar, T. F.; Schechter, R. S.

    1980-01-01

    Describes research on in situ processing to develop necessary theory and understanding of the underground process to facilitate commercialization of a wide range of mineral deposits. Goal is to produce laboratory and computer-based tools to allow site evaluation based on field and laboratory measurements of mineral and associated overburdens.…

  4. Microstructure and superconducting properties of nanocarbon-doped internal Mg diffusion-processed MgB2 wires fabricated using different boron powders

    NASA Astrophysics Data System (ADS)

    Xu, Da; Wang, Dongliang; Li, Chen; Yuan, Pusheng; Zhang, Xianping; Yao, Chao; Dong, Chiheng; Huang, He; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-04-01

    MgB2/Nb/Monel monofilament wires were fabricated using four different boron powders by an internal Mg diffusion (IMD) process. The microstructure, morphology and the critical current density (J c) of the used boron powders and the formative MgB2 layers were analyzed and compared. It was found that the purity and particle size of the boron powder influence the superconducting properties of MgB2 wires; further that the optimized heat-treatment condition also depends on the quality of the boron powder. The highest J c was obtained in the MgB2 layer made using amorphous boron (AB) powder, although a certain amount of voids existed in the superconducting layer. The IMD-processed MgB2 layer fabricated using high-purity boron (HB) powder had also a high J c compared with the powder-in-tube (PIT) process and a few unreacted boron particles remained in it. MgB2 wire fabricated using low-purity boron (LB) powder had a high cost-performance ratio compared with the others, which is expected to allow the fabrication of large-scale and low-cost superconducting wires for practical application. However, the enhancement of the J c was not found in the MgB2 layer manufactured using the ball-milled LB (MLB) powder as expected due to the increased percentage of impurity.

  5. Evaluation of Young’s modulus of MgB2 filaments in composite wires for the superconducting links for the high-luminosity LHC upgrade

    NASA Astrophysics Data System (ADS)

    Sugano, Michinaka; Ballarino, Amalia; Bartova, Barbora; Bjoerstad, Roger; Gerardin, Alexandre; Scheuerlein, Christian

    2016-02-01

    MgB2 wire is a promising superconductor for the superconducting links for the high-luminosity upgrade of the large Hadron collider at CERN. The mechanical properties of MgB2 must be fully quantified for the cable design, and in this study, we evaluate the Young’s modulus of MgB2 filaments in wires with a practical level of critical current. The Young’s moduli of MgB2 filaments by two different processes, in situ and ex situ, were compared. Two different evaluation methods were applied to an in situ MgB2 wire, a single-fiber tensile test and a tensile test after removing Monel. In addition, the Young’s modulus of the few-micron-thick Nb-Ni reaction layer in an ex situ processed wire was evaluated using a nanoindentation testing technique to improve the accuracy of analysis based on the rule of mixtures. The Young’s moduli of the in situ and ex situ MgB2 wires were in the range of 76-97 GPa and no distinct difference depending on the fabrication process was found.

  6. Uniform transport performance of a 100 m-class multifilament MgB2 wire fabricated by an internal Mg diffusion process

    NASA Astrophysics Data System (ADS)

    Wang, Dongliang; Xu, Da; Zhang, Xianping; Yao, Chao; Yuan, Pusheng; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2016-06-01

    A 100 m long six-filament MgB2 wire was successfully fabricated using an internal magnesium diffusion (IMD) process. We investigated the transport properties and the uniformity of this long multifilament IMD wire. The MgB2 layer and the sub-filament region are regular, and the J c values have a fairly homogenous distribution throughout the wire, suggesting that there were no obvious defects along the length of the wire. The uniformity problem of long multifilament IMD MgB2 wires can be mitigated by optimizing the starting composite parameters, multifilament geometry, fabricating process and annealing conditions. A layer J c as high as 1.2 × 105 A cm-2 at 4.2 K and 8 T was obtained, which was comparable with the highest reported value for a short multifilament IMD wire. The transport layer J c, non-barrier J c and J e values are independent of the wire diameter. In addition, the analysis of the stress-strain characteristics and the n value of the IMD wire is also presented. These results indicate that the long multifilament IMD-processed MgB2 superconducting wire is suitable for practical applications.

  7. RAPID COMMUNICATION: Formation of MgB2 at ambient temperature with an electrochemical process: a plausible mechanism

    NASA Astrophysics Data System (ADS)

    Jadhav, A. B.; Subhedar, K. M.; Hyam, R. S.; Talaptra, A.; Sen, Pintu; Bandyopadhyay, S. K.; Pawar, S. H.

    2005-06-01

    The binary intermetallic MgB2 superconductor has been synthesized by many research groups. However, the mechanism of its formation is not clearly understood. In this communication, a comprehensive mechanism of the formation of MgB2 from Le Chatelier's principle of equilibrium reaction has been explained both for solid-state reaction and electrodeposition methods.

  8. High-performance MgB2 superconducting wires for use under liquid-helium-free conditions fabricated using an internal Mg diffusion process

    NASA Astrophysics Data System (ADS)

    Ye, ShuJun; Song, Minghui; Matsumoto, Akiyoshi; Togano, Kazumasa; Takeguchi, Masaki; Ohmura, Takahito; Kumakura, Hiroaki

    2013-12-01

    MgB2 has a superconducting transition temperature (Tc) of 39 K, which is much higher than that for practical metallic superconductors. Thus, it is hoped that MgB2 can not only replace metallic superconductors, but can be used under liquid-helium-free conditions, for example, at temperatures of 10-20 K that can easily be achieved using cryocooling systems. However, to date, the reported critical current density (Jc) for MgB2 wires is not high enough for large-scale applications in liquid-helium-free conditions. In the present study, successful fabrication of high-performance MgB2 superconducting wires was carried out using an internal Mg diffusion (IMD) process, involving a p-dimethylbenzene (C8H10) pre-treatment of carbon-coated B powder with nanometer-sized particles. The resulting wires exhibited the highest ever Jc of 1.2 × 105 A cm-2 at 4.2 K and 10 T, and an engineering critical current density (Je) of about 1 × 104 A cm-2. Not only in 4.2 K, but also in 10 K, the Jc values for the wires fabricated in the present study are in fact higher than that for Nb-Ti wires at 4.2 K for the magnetic fields at which the measurements were carried out. At 20 K and 5 T, the Jc and Je were about 7.6 × 105 A cm-2 and 5.3 × 103 A cm-2, respectively, which are the highest values reported for MgB2 wires to date. The results of a detailed microstructural analysis suggested that the main reason for the superior electrical performance was the high density of the MgB2 layer rather than just the small grain size, and that the critical current could be further increased by suitable control of the microstructure. These high-performance IMD-processed MgB2 wires are thus promising superconductors for applications such as magnetic resonance imaging and maglev trains that can operate under liquid-helium-free conditions.

  9. Improved Jc-B properties of MgB2 multifilamentary wires and tapes

    NASA Astrophysics Data System (ADS)

    Wang, Chengduo; Wang, Dongliang; Zhang, Xianping; Yao, Chao; Wang, Chunlei; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2012-12-01

    MgB2 multifilamentary wires and tapes were fabricated by the in situ powder-in-tube (PIT) process using acetone doped milled precursor powders. The critical current density of MgB2 is strongly enhanced by high energy milling and acetone doping. Furthermore, the liquid acetone can restrain the agglomeration of milled powder, which is beneficial to the fabrication of MgB2 multifilamentary wires. At 4.2 K and 10 T, the Jc of the 80 h doped Fe/Cu wire is 2.9 × 103 A cm-2, 20 times larger than that of the 1 h pure one (the ‘1 h’ and ‘80 h’, refer to ball milling times). The Jc of 80 h doped Fe/Monel tape is up to 9.2 × 103 A cm-2 at 4.2 K and 10 T. The Jc values of Nb barrier wires are comparable to those of the Fe barrier MgB2 wires. These results indicate that the addition of liquid C-containing material during high energy milling may be an effective way to get excellent properties of MgB2 for practical applications.

  10. Enhancement of critical current of SiC and malic acid codoped MgB2/Fe wires

    NASA Astrophysics Data System (ADS)

    Li, W. X.; Chen, R. H.; Xu, X.; Hu, Y. M.; Zhu, M. Y.; Li, Y.; Dou, S. X.

    2015-09-01

    The influences of microstructure, connectivity, and disorder on the critical current density, Jc, are discussed to clarify the different mechanisms of Jc(H) in different magnetic field ranges for in situ and combined in situ/ex situ MgB2/Fe wires with nano SiC and malic acid codoping. Sintering temperature plays a very important role in the electromagnetic properties at different temperatures and under various magnetic fields. Connectivity, upper critical field, Hc2, and irreversibility field, Hirr, are studied to demonstrate the mechanism of Jc dependence on magnetic field. The combined in situ/ex situ process is proved to be a promising technique for fabrication of practical MgB2 wires.

  11. A trapped magnetic field of 3 T in homogeneous, bulk MgB2 superconductors fabricated by a modified precursor infiltration and growth process

    NASA Astrophysics Data System (ADS)

    Bhagurkar, A. G.; Yamamoto, A.; Anguilano, L.; Dennis, A. R.; Durrell, J. H.; Babu, N. Hari; Cardwell, D. A.

    2016-03-01

    The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB2 bulk superconductors by the infiltration and growth (IG) process. Poor wetting characteristics can therefore result potentially in non-uniform infiltration, formation of defects in the final sample structure and poor structural homogeneity throughout the bulk material. Here we report the fabrication of near-net-shaped MgB2 bulk superconductors by a modified precursor infiltration and growth (MPIG) technique. A homogeneous bulk microstructure has subsequently been achieved via the uniform infiltration of Mg liquid by enriching pre-reacted MgB2 powder within the green precursor pellet as a wetting enhancer, leading to relatively little variation in superconducting properties across the entire bulk sample. Almost identical values of trapped magnetic field of 2.12 T have been measured at 5 K at both the top and bottom surfaces of a sample fabricated by the MPIG process, confirming the uniformity of the bulk microstructure. A maximum trapped field of 3 T has been measured at 5 K at the centre of a stack of two bulk MgB2 samples fabricated using this technique. A steady rise in trapped field was observed for this material with decreasing temperature down to 5 K without the occurrence of flux avalanches and with a relatively low field decay rate (1.5%/d). These properties are attributed to the presence of a fine distribution of residual Mg within the bulk microstructure generated by the MPIG processing technique.

  12. The role of various boron precursor on superconducting properties of MgB2/Fe

    NASA Astrophysics Data System (ADS)

    Safran, S.; Kılıçarslan, E.; Kılıç, A.; Gencer, A.

    2014-09-01

    The superconducting properties of Fe sheathed MgB2 wire has been studied as a function of precursor B powder particle size. The in situ processed MgB2 samples were prepared by means of conventional solid state reaction method with magnesium powder (99.8%, 325 mesh) and three different types of amorphous boron powders (purity; 98.8%, >95% and 91.9%) from two sources, Pavezyum (Turkish supplier) and Sigma Aldrich. The particle sizes of Turkish boron precursor powder were selected between 300 and 800 nm. The structural and magnetic properties of the prepared samples were investigated by means of the X-ray powder diffraction (XRD) and ac susceptibility measurements. The XRD patterns showed that the diffraction peaks for our samples belong to the main phase of the MgB2 diffraction patterns. The highest critical temperature, Tc = 38.4 K was measured for the MgB2 sample which was fabricated by using the 98.8% B. The critical current density of this sample was extracted from the magnetization measurements and Jc = 5.4 × 105 A cm-2 at 5 K and B = 2 T. We found that the sample made by using the 98.8% boron showed almost 2 times higher Jc than that of obtained from 91.9% B powder.

  13. Critical current density and pinning behaviour of mono-core MgB2 wires prepared by internal magnesium diffusion and in-situ powder-in-tube method

    NASA Astrophysics Data System (ADS)

    Brunner, Boris; Kováč, Pavol; Reissner, Michael; Hušek, Imrich; Melišek, Tibor; Pardo, Enric

    2014-10-01

    Mono-core MgB2 wires were produced by internal magnesium diffusion (IMD) and in-situ powder-in-tube (PIT) technique. Hysteresis loops and magnetic relaxations were measured to calculate critical current density, Jcm (via Bean’s critical state model) and mean effective activation energy (via Anderson’s flux creep theory). To calculate Jcm of the IMD sample, the formulae for typical cylindrical sample geometry must have been modified properly with regard to IMD hollow cylinder geometry. Results for Jcm were compared to direct transport measurements. Also studied was the irreversibility field, Birr, and upper critical field, Bc2. It was found that the dominant difference between wires is in Jc. For the IMD sample, Jc was higher and less field-dependent than Jc of the PIT sample.

  14. Electro-mechanical characterization of MgB2 wires for the Superconducting Link Project at CERN

    NASA Astrophysics Data System (ADS)

    Konstantopoulou, K.; Ballarino, A.; Gharib, A.; Stimac, A.; Garcia Gonzalez, M.; Perez Fontenla, A. T.; Sugano, M.

    2016-08-01

    In previous years, the R & D program between CERN and Columbus Superconductors SpA led to the development of several configurations of MgB2 wires. The aim was to achieve excellent superconducting properties in high-current MgB2 cables for the HL-LHC upgrade. In addition to good electrical performance, the superconductor shall have good mechanical strength in view of the stresses during operation (Lorenz forces and thermal contraction) and handling (tension and bending) during cabling and installation at room temperature. Thus, the study of the mechanical properties of MgB2 wires is crucial for the cable design and its functional use. In the present work we report on the electro-mechanical characterization of ex situ processed composite MgB2 wires. Tensile tests (critical current versus strain) were carried out at 4.2 K and in a 3 T external field by means of a purpose-built bespoke device to determine the irreversible strain limit of the wire. The minimum bending radius of the wire was calculated taking into account the dependence of the critical current with the strain and it was then used to obtain the minimum twist pitch of MgB2 wires in the cable. Strands extracted from cables having different configurations were tested to quantify the critical current degradation. The Young’s modulus of the composite wire was measured at room temperature. Finally, all measured mechanical parameters will be used to optimize an 18-strand MgB2 cable configuration.

  15. Fabrication and properties of kilometer level, Nb reinforced, 6 filamentary MgB2 wires

    NASA Astrophysics Data System (ADS)

    Li, C. S.; Yan, G.; Wang, Q. Y.; Jiao, G. F.; Sulpice, A.; Yang, F.; Xiong, X. M.; Liu, G. Q.; Feng, J. Q.; Feng, Y.; Zhang, P. X.

    2013-11-01

    Kilometer level 6 + 1 filamentary MgB2 wires sheathed with Nb/Cu composite tube was fabricated by in situ powder-in-tube (PIT) method, nonferromagnetic Nb was employed as the centre reinforced materials. There is no any annealing in the whole fabrication process due to the excellent ductility of Nb/Cu based tube. The (Mg, B)/Nb/Cu composite wire was fabricated to the target size of 1.4 mm in diameter and heat treated at 680 °C for 2 h in a vacuum furnace. Microstructure, superconductivity, mechanical properties and homogeneity of critical current were measured respectively. The transport engineering critical current density (Jce) reaches 2.5 × 104 A/cm2 at 20 K, 1 T. The results show a good potential to fabricate high performance MgB2 wires at ambient pressure for practical application.

  16. Microstructures and critical currents of single- and multi-filamentary MgB2 superconducting wires fabricated by an internal Mg diffusion process

    NASA Astrophysics Data System (ADS)

    Togano, K.; Hur, J.; Matsumoto, A.; Kumakura, H.

    2010-08-01

    A single-filament wire and 7- and 19-filament wires of MgB2 superconductor were fabricated by an internal Mg diffusion (IMD) process. The wire is sheathed by a Cu-Ni alloy and each filament is composed of an outermost Ta, an intermediate B + SiC powder layer and an Mg core at the center. Despite the large total area reduction, the cross sections of all wires show uniform deformation of the composite. During the subsequent heat treatment, a reacted layer with a dense composite structure composed of a MgB2 matrix and fine particles is formed by Mg liquid infiltration and the reaction with the B + SiC powder. For all wires, the highest transport Ic was obtained at furnace temperatures of 640-645 °C, which is just below the melting point of Mg. In the single-filament wire, a fairly large amount of B + SiC remains outside the reacted layer, while the residual B + SiC is much reduced in the multi-filamentary wires, resulting in higher Ic, than that of the single-filament wire. However, the Jc, estimated for the reacted layer is not so different between the wires. When the heat treatment temperature exceeds 650 °C, the Ic value rapidly decreases, although the volume fraction of the MgB2 detected continues to increase. It is observed that the thickness of the reacted layer formed at higher temperatures becomes significantly inhomogeneous, which is thought to be responsible for the deterioration of transport Ic values. The highest Jc(layer) estimated for the reacted layer is as high as 9.9 × 104 A cm - 2 at 4.2 K and 10 T and 3.3 × 105 A cm - 2 at 20 K and 1 T achieved for the multi-filamentary wires. The Jc(core) estimated for the area including the hole and remnant B is about 1/3 of the Jc(layer). From good workability of the composite and excellent Jc values, it is expected that the IMD process can compete in terms of practical wire fabrication with the conventional powder-in-tube (PIT) process.

  17. Effect of cold isostatic pressing on the transport current of filamentary MgB2 wire made by the IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Pachla, W.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.

    2016-07-01

    This work describes the effect of cold isostatic pressing applied to as-drawn filamentary wires in a GlidCop and/or Cu sheath made by the internal magnesium diffusion process. Critical currents of as-drawn and isostatically pressed wires at high pressures up to 2.0 GPa followed by heat treatment at 640 °C for 40 min were measured. The obtained results show an improvement in boron powder density resulting in an increase of the critical current of MgB2 layers. The engineering current density increases by 4–13 times after the high-pressure treatment, and is influenced by the density of the boron powder and by the mechanical strength of the outer sheath.

  18. Effect of cold isostatic pressing on the transport current of filamentary MgB2 wire made by the IMD process

    NASA Astrophysics Data System (ADS)

    Kováč, P.; Hušek, I.; Pachla, W.; Melišek, T.; Kulich, M.; Rosová, A.; Kopera, L.

    2016-07-01

    This work describes the effect of cold isostatic pressing applied to as-drawn filamentary wires in a GlidCop and/or Cu sheath made by the internal magnesium diffusion process. Critical currents of as-drawn and isostatically pressed wires at high pressures up to 2.0 GPa followed by heat treatment at 640 °C for 40 min were measured. The obtained results show an improvement in boron powder density resulting in an increase of the critical current of MgB2 layers. The engineering current density increases by 4-13 times after the high-pressure treatment, and is influenced by the density of the boron powder and by the mechanical strength of the outer sheath.

  19. Enhanced Transport Currents in Cu-Sheathed MgB2 Wires

    SciTech Connect

    Eisterer, M; Glowacki, B A.; Weber, H W.; Greenwood, Lawrence R. ); Majoros, M

    2002-01-01

    Copper sheathed MgB2 wires, prepared by an in-situ process, were exposed to neutron radiation in order to introduce defects into the superconductor. The high level of disorder (4.6 x 10{sup -2} dpa) leads to a decreases of the transition temperature by more than 4 K, but to an increase of the slope of the irreversibility line, thus resulting in higher irreversibility fields at low temperatures. The transport currents are significantly enhanced at 4.2 K for fields above 2 T.

  20. Semiconductors: In Situ Processing of Photovoltaic Devices

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.

    1998-01-01

    Current proposals for developing an extended human presence on the Moon and Mars increasingly consider the processing of nonterrestrial materials essential for keeping the Earth launch burden reasonable. Utilization of in situ resources for construction of lunar and Mars bases will initially require assessment of resource availability followed by the development of economically acceptable and technically feasible extraction processes. In regard to materials processing and fabrication, the lower gravity level on the Moon (0.125 g) and Mars (0.367 g) will dramatically change the presently accepted hierarchy of materials in terms of specific properties, a factor that must be understood and exploited. Furthermore, significant changes are expected in the behavior of liquid materials during processing. In casting, for example, mold filling and associated solidification processes have to be reevaluated. Finally, microstructural development, and therefore material properties, presently being documented through ongoing research in microgravity science and applications, need to be understood and scaled to the reduced gravity environments.

  1. Magnetic lenses using different MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Y.; Choi, S.; Matsumoto, S.; Teranishi, R.; Giunchi, G.; Figini Albisetti, A.; Kiyoshi, T.

    2012-02-01

    A magnetic lens allows the concentration of magnetic fields using the diamagnetism of superconductors. The important features of the magnetic lens are a tapered inner diameter from which the magnetic flux is extruded and a slit to suppress the circumference current that shields the magnetic flux. This concept was experimentally confirmed through the use of GdBaCuO bulks and a stack of NbTi/Nb/Cu sheets. We refer to this arrangement as a magnetic lens. The Mg-reactive liquid infiltration (Mg-RLI) process developed by Edison SpA is suitable for the production of large and high-density MgB2 bulks. Three MgB2 bulk magnetic lenses, each with a different microstructure, were fabricated following the Mg-RLI process. The properties of the MgB2 magnetic lenses were measured in a cryocooler system as well as in liquid helium. The results confirmed that the MgB2 bulk magnetic lenses could concentrate a magnetic field and that their field concentration properties were greatly affected by the temperature and the external field. In addition, the microstructure of the MgB2 bulk also had an influence on the magnetic properties at different external fields. The results indicated that the MgB2 lens might be utilized as a field amplifier in intermediate fields.

  2. Effects of three different homemade nanocarbons doping on the superconducting properties of MgB2 tapes

    NASA Astrophysics Data System (ADS)

    Wang, Dongliang; Zhang, Haitao; Zhang, Xianping; Tang, Shaopu; Ma, Yanwei; Oguro, Hidetoshi; Awaji, Satoshi; Watanabe, Kazuo

    2015-01-01

    The doping effects of three different homemade nanocarbons on microstructure and superconducting properties of in situ powder-in-tube (PIT) processed MgB2/Fe tapes were studied. Compared with pure tapes, all homemade nano-carbon additions led to an order of magnitude enhancement of the supercurrent at 4.2 K, 10 T. Among them, hollow carbon nanoboxes doped samples exhibited the highest transport Jc-B properties, about 3.4 × 104 A cm-2 at 4.2 K, 10 T (Je ∼ 104 A cm-2). The large Jc improvements of doped samples are thought to be attributed to the enhancement of flux pinning force. It is also interesting that the change of microstructure and critical field of three nanocarbons doped MgB2 samples are not obvious, which mainly because that the performance parameters of these nanocarbons with different morphologies are almost same.

  3. In Situ Field Testing of Processes

    SciTech Connect

    J. Wang

    2001-12-14

    The purpose of this Analysis/Model Report (AMR) is to update and document the data and subsequent analyses from ambient field-testing activities performed in underground drifts of the Yucca Mountain Site Characterization Project (YMP). This revision updates data and analyses presented in the initial issue of this AMR. This AMR was developed in accordance with the ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' and ''Technical Work Plan for UZ Flow, Transport, and Coupled Processes Process Model Report. These activities were performed to investigate in situ flow and transport processes. The evaluations provide the necessary framework to: (1) refine and confirm the conceptual model of matrix and fracture processes in the unsaturated zone (UZ) and (2) analyze the impact of excavation (including use of construction water and effect of ventilation) on the UZ flow and transport processes. This AMR is intended to support revisions to ''Conceptual and Numerical Models for UZ Flow and Transport'' and ''Unsaturated Zone Flow and Transport Model Process Model Report''. In general, the results discussed in this AMR are from studies conducted using a combination or a subset of the following three approaches: (1) air-injection tests, (2) liquid-release tests, and (3) moisture monitoring using in-drift sensors or in-borehole sensors, to evaluate the impact of excavation, ventilation, and construction-water usage on the surrounding rocks. The liquid-release tests and air-injection tests provide an evaluation of in situ fracture flow and the competing processes of matrix imbibition. Only the findings from testing and data not covered in the ''Seepage Calibration Model and Seepage Testing Data'' are analyzed in detail in the AMR.

  4. Situ process for making multifunctional fuel additives

    SciTech Connect

    Carrier, R.C.; Allen, B.R.

    1984-02-28

    Disclosed is an in situ or ''one pot'' process for making a fuel additive comprising reacting an excess of at least one N-primary alkylalkylene diamine with maleic anhydride in the presence of from 20 to 36 weight percent of a mineral oil reaction diluent at a temperature ranging from ambient to about 225/sup 0/ F. and recovering a product containing a primary aliphatic hydrocarbon amino alkylene substituted asparagine, an N-primary alkylalkylene diamine in the reaction oil with the product having a by-product succinimide content not in excess of 1.0 weight percent, based on the weight of asparagine present.

  5. Variation of pinning mechanism and enhancement of critical current density in MgB2 bulk containing self-generated coherent MgB4 impurity

    NASA Astrophysics Data System (ADS)

    Cai, Qi; Liu, Yongchang; Ma, Zongqing; Li, Huijun; Yu, Liming

    2013-09-01

    Bulk MgB2, with self-generated MgB4 pinning centers, have experienced two-step sintering process, initially at 750 °C and then 900-1000 °C. On the contrary to the widely accepted point that MgB4 deteriorates superconductivity, it was found that MgB4 played a significant role in enhancing critical current density. The precipitation pattern of MgB4 was studied from the lattice scale images. It was observed that the initial coherent relation between the MgB4 and the matrix was destroyed to become semi-coherent and even incoherent as the second-step sintering temperature increased. Owing to the lattice distortion caused by the elastic accommodation of the coherent interface, the small-sized MgB4 particles controlled by the sintering temperature, and the fine grain connectivity affected by the porosity, the critical current density was improved over the entire magnetic field. Finally, the dominating pinning mechanism within the crystal was confirmed to be Δκ pinning in the two-step sintered MgB2 sample, where the κ is the Ginzburg-Landau parameter, while the mechanism of one-step sintered sample is surface pinning.

  6. Natural attenuation processes during in situ capping.

    PubMed

    Himmelheber, David W; Pennell, Kurt D; Hughes, Joseph B

    2007-08-01

    Chlorinated solvents are common groundwater contaminants that threaten surface water quality and benthic health when present in groundwater seeps. Aquatic sediments can act as natural biobarriers to detoxify chlorinated solvent plumes via reductive dechlorination. In situ sediment capping, a remedial technique in which clean material is placed at the sediment-water interface, may alter sedimentary natural attenuation processes. This research explores the potential of Anacostia River sediment to naturally attenuate chlorinated solvents under simulated capping conditions. Results of microcosm studies demonstrated that intrinsic dechlorination of dissolved-phase PCE to ethene was possible, with electron donor availability controlling microbial activity. A diverse microbial community was present in the sediment, including multiple Dehalococcoides strains indicated by the amplification of the reductive dehalogenases tceA, vcrA, and bvcA. An upflow column simulating a capped sediment bed subject to PCE-contaminated groundwater seepage lost dechlorination activity with time and only achieved complete dechlorination when microorganisms present in the sediment were provided electron donor. Increases in effluent chloroethene concentrations during the period of biostimulation were attributed to biologically enhanced desorption and the formation of less sorptive dechlorination products. These findings suggest that in situ caps should be designed to account for reductions in natural biobarrier reactivity and for the potential breakthrough of groundwater contaminants. PMID:17822095

  7. Natural attenuation processes during in situ capping.

    PubMed

    Himmelheber, David W; Pennell, Kurt D; Hughes, Joseph B

    2007-08-01

    Chlorinated solvents are common groundwater contaminants that threaten surface water quality and benthic health when present in groundwater seeps. Aquatic sediments can act as natural biobarriers to detoxify chlorinated solvent plumes via reductive dechlorination. In situ sediment capping, a remedial technique in which clean material is placed at the sediment-water interface, may alter sedimentary natural attenuation processes. This research explores the potential of Anacostia River sediment to naturally attenuate chlorinated solvents under simulated capping conditions. Results of microcosm studies demonstrated that intrinsic dechlorination of dissolved-phase PCE to ethene was possible, with electron donor availability controlling microbial activity. A diverse microbial community was present in the sediment, including multiple Dehalococcoides strains indicated by the amplification of the reductive dehalogenases tceA, vcrA, and bvcA. An upflow column simulating a capped sediment bed subject to PCE-contaminated groundwater seepage lost dechlorination activity with time and only achieved complete dechlorination when microorganisms present in the sediment were provided electron donor. Increases in effluent chloroethene concentrations during the period of biostimulation were attributed to biologically enhanced desorption and the formation of less sorptive dechlorination products. These findings suggest that in situ caps should be designed to account for reductions in natural biobarrier reactivity and for the potential breakthrough of groundwater contaminants.

  8. An innovative technique to synthesize C-doped MgB2 by using chitosan as the carbon source

    NASA Astrophysics Data System (ADS)

    Bovone, G.; Vignolo, M.; Bernini, C.; Kawale, S.; Siri, A. S.

    2014-02-01

    Here, we report a new technique to synthesize carbon-doped MgB2 powder. Chitosan was innovatively used as the carbon source during the synthesis of boron from boron oxide. This allowed the introduction of local defects, which later on served as pinning centers in MgB2, in the boron lattice itself, avoiding the traditional and time consuming ways of ex situ MgB2 doping (e.g. ball milling). Two volume percentages of C-doping have been tried and its effect on the superconducting properties, evaluated by magnetic and transport measurements, are discussed here. Morphological analysis by scanning electron microscopy revealed nano-metric grains’ distribution in the boron and MgB2 powder. Mono-filamentary MgB2 wires have been fabricated by an ex situ powder-in-tube technique by using the thus prepared carbon-doped MgB2 and pure MgB2 powders. Transport property measurements on these wires were made and compared with MgB2 wire produced using commercial boron.

  9. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... in situ processing activities shall comply with 30 CFR 817 and this section. (b) In situ processing... processing activities shall submit for approval as part of the application for permit under 30 CFR 785.22... mining and recovery process are promptly treated, confined, or disposed of, in a manner that...

  10. In situ vitrification: Process and products

    SciTech Connect

    Kindle, C.; Koegler, S.

    1991-06-01

    In situ vitrification (ISV) is an electrically powered thermal treatment process that converts soil into a chemically inert and stable glass and crystalline product. It is similar in concept to bringing a simplified glass manufacturing process to a site and operating it in the ground, using the soil as a glass feed stock. Gaseous emissions are contained, scrubbed, and filtered. When the process is completed, the molten volume cools producing a block of glass and crystalline material that resembles natural obsidian commingled with crystalline phases. The product passes US Environmental Protection Agency (EPA) leach resistance tests, and it can be classified as nonhazardous from a chemical hazard perspective. ISV was developed by the Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE) for application to contaminated soils. It is also being adapted for applications to buried waste, underground tanks, and liquid seepage sites. ISV's then-year development period has included tests on many different site conditions. As of January 1991 there have been 74 tests using PNL's ISV equipment; these tests have ranged from technology development tests using nonhazardous conditions to hazardous and radioactive tests. 2 refs., 6 figs., 7 tabs.

  11. Support Routines for In Situ Image Processing

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Pariser, Oleg; Yeates, Matthew C.; Lee, Hyun H.; Lorre, Jean

    2013-01-01

    This software consists of a set of application programs that support ground-based image processing for in situ missions. These programs represent a collection of utility routines that perform miscellaneous functions in the context of the ground data system. Each one fulfills some specific need as determined via operational experience. The most unique aspect to these programs is that they are integrated into the large, in situ image processing system via the PIG (Planetary Image Geometry) library. They work directly with space in situ data, understanding the appropriate image meta-data fields and updating them properly. The programs themselves are completely multimission; all mission dependencies are handled by PIG. This suite of programs consists of: (1)marscahv: Generates a linearized, epi-polar aligned image given a stereo pair of images. These images are optimized for 1-D stereo correlations, (2) marscheckcm: Compares the camera model in an image label with one derived via kinematics modeling on the ground, (3) marschkovl: Checks the overlaps between a list of images in order to determine which might be stereo pairs. This is useful for non-traditional stereo images like long-baseline or those from an articulating arm camera, (4) marscoordtrans: Translates mosaic coordinates from one form into another, (5) marsdispcompare: Checks a Left Right stereo disparity image against a Right Left disparity image to ensure they are consistent with each other, (6) marsdispwarp: Takes one image of a stereo pair and warps it through a disparity map to create a synthetic opposite- eye image. For example, a right eye image could be transformed to look like it was taken from the left eye via this program, (7) marsfidfinder: Finds fiducial markers in an image by projecting their approximate location and then using correlation to locate the markers to subpixel accuracy. These fiducial markets are small targets attached to the spacecraft surface. This helps verify, or improve, the

  12. Doping effects of carbon and titanium on the critical current density of MgB2

    NASA Astrophysics Data System (ADS)

    Shen, T. M.; Li, G.; Cheng, C. H.; Zhao, Y.

    2006-11-01

    MgB2 bulks doped with Ti or/and C were prepared by an in situ solid state reaction method to determine the combined effect of C and Ti doping and to probe the detailed mechanism. The magnetization measurement shows that Mg0.95Ti0.05B1.95C0.05 sample has significantly improved flux pinning compared to the MgB1.95C0.05 sample at 20 K, indicating that C and Ti are largely cooperative in improving the Jc(H) behaviour. No TiC phase was detected in the x-ray diffraction (XRD) patterns. Moreover, the overlap of the (100) peaks of MgB1.95C0.05 and Mg0.95Ti0.05B1.95C0.05 showed that Ti doping does not reduce the amount of C in MgB2. Microstructural analyses revealed that the addition of Ti eliminated the porosity present in the carbon-doped MgB2 pellet, resulting in an improved intergrain connectivity and an increase of effective current pass. Further, MgB2 doped with C and Ti, which mainly consists of spherical grains about 200-300 nm in size, shows an higher grain homogeneity than the C-doped sample, suggesting that the Ti doping in MgB1-xCx has played an important role in obtaining uniform grains.

  13. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., to ensure that the potential for use of the ground water is not diminished. (Pub. L. 95-87, 30 U.S.C... in situ processing activities shall comply with 30 CFR 817 and this section. (b) In situ processing... processing activities shall submit for approval as part of the application for permit under 30 CFR...

  14. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... in situ processing activities shall comply with 30 CFR 817 and this section. (b) In situ processing... processing activities shall submit for approval as part of the application for permit under 30 CFR 785.22, and follow after approval, a plan that ensures that all acid-forming, toxic-forming, or...

  15. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... in situ processing activities shall comply with 30 CFR 817 and this section. (b) In situ processing... processing activities shall submit for approval as part of the application for permit under 30 CFR 785.22, and follow after approval, a plan that ensures that all acid-forming, toxic-forming, or...

  16. 30 CFR 828.11 - In situ processing: Performance standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... in situ processing activities shall comply with 30 CFR 817 and this section. (b) In situ processing...) Avoiding discharge of fluids into holes or wells, other than as approved by the regulatory authority; (2) Injecting process recovery fluids only into geologic zones or intervals approved as production zones by...

  17. Superconducting characteristics of short MgB2 wires of long level sensor for liquid hydrogen

    NASA Astrophysics Data System (ADS)

    Takeda, M.; Inoue, Y.; Maekawa, K.; Matsuno, Y.; Fujikawa, S.; Kumakura, H.

    2015-12-01

    To establish the worldwide storage and marine transport of hydrogen, it is important to develop a high-precision and long level sensor, such as a superconducting magnesium diboride (MgB2) level sensor for large liquid hydrogen (LH2) tanks on board ships. Three 1.7- m-long MgB2 wires were fabricated by an in situ method, and the superconducting characteristics of twenty-four 20-mm-long MgB2 wires on the 1.7-m-long wires were studied. In addition, the static level-detecting characteristics of five 500-mm-long MgB2 level sensors were evaluated under atmospheric pressure.

  18. IN SITU FIELD TESTING OF PROCESSES

    SciTech Connect

    J.S.Y. YANG

    2004-11-08

    The purpose of this scientific analysis report is to update and document the data and subsequent analyses from ambient field-testing activities performed in underground drifts and surface-based boreholes through unsaturated zone (UZ) tuff rock units. In situ testing, monitoring, and associated laboratory studies are conducted to directly assess and evaluate the waste emplacement environment and the natural barriers to radionuclide transport at Yucca Mountain. This scientific analysis report supports and provides data to UZ flow and transport model reports, which in turn contribute to the Total System Performance Assessment (TSPA) of Yucca Mountain, an important document for the license application (LA). The objectives of ambient field-testing activities are described in Section 1.1. This report is the third revision (REV 03), which supercedes REV 02. The scientific analysis of data for inputs to model calibration and validation as documented in REV 02 were developed in accordance with the Technical Work Plan (TWP) ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (BSC 2004 [DIRS 167969]). This revision was developed in accordance with the ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 1.2.4) for better integrated, consistent, transparent, traceable, and more complete documentation in this scientific analysis report and associated UZ flow and transport model reports. No additional testing or analyses were performed as part of this revision. The list of relevant acceptance criteria is provided by ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654]), Table 3-1. Additional deviations from the TWP regarding the features, events, and processes (FEPs) list are discussed in Section 1.3. Documentation in this report includes descriptions of how, and under what conditions, the tests were conducted. The descriptions and

  19. Development of hot-electron THz bolometric mixers using MgB2 thin films

    NASA Astrophysics Data System (ADS)

    Cunnane, Daniel; Kawamura, Jonathan; Karasik, Boris S.; Wolak, Matthaeus A.; Xi, X. X.

    2014-07-01

    Terahertz high-resolution spectroscopy of interstellar molecular clouds greatly relies on hot-electron superconducting bolometric (HEB) mixers. Current state-of-the-art receivers use mixer devices made from ultrathin (~ 3-5 nm) films of NbN with critical temperature ~ 9-11 K. Such mixers have been deployed on a number of groundbased, suborbital, and orbital platforms including the HIFI instrument on the Hershel Space Observatory. Despite its good sensitivity and well-established fabrication process, the NbN HEB mixer suffers from the narrow intermediate frequency (IF) bandwidth ~ 2-3 GHz and is limited to operation at liquid Helium temperature. As the heterodyne receivers are now trending towards "high THz" frequencies, the need in a larger IF bandwidth becomes more pressing since the same velocity resolution for a Doppler shifted line at 5 THz requires a 5-times greater IF bandwidth than at 1 THz. Our work is focusing on the realization of practical HEB mixers using ultrathin (10-20 nm) MgB2 films. They are prepared using a Hybrid Physical-Chemical Vapor Deposition (HPCVD) process yielding ultrathin films with critical temperature ~ 37-39 K. The expectation is that the combination of small thickness, high acoustic phonon transparency at the interface with the substrate, and very short electron-phonon relaxation time may lead to IF bandwidth ~ 10 GHz or even higher. SiC continues to be the most favorable substrate for MgB2 growth and as a result, a study has been conducted on the transparency of SiC at THz frequencies. FTIR measurements show that semi-insulating SiC substrates are at least as transparent as Si up to 2.5 THz. Currently films are passivated using a thin (10 nm) SiO2 layer which is deposited ex-situ via RF magnetron sputtering. Micron-sized spiral antenna-coupled HEB mixers have been fabricated using MgB2 films as thin as 10 nm. Fabrication was done using contact UV lithography and Ar Ion milling, with E-beam evaporated Au films deposited for the

  20. Study of the microwave electrodynamic response of MgB 2 thin films

    NASA Astrophysics Data System (ADS)

    Andreone, A.; Cassinese, A.; Cantoni, C.; Di Gennaro, E.; Lamura, G.; Maglione, M. G.; Paranthaman, M.; Salluzzo, M.; Vaglio, R.

    2002-08-01

    We present a study on the power dependence of the microwave surface impedance in thin films of the novel superconductor MgB 2. 500 nm thick samples exhibiting critical temperatures ranging between 26 and 38 K are synthesized by an ex situ post-anneal of e-beam evaporated boron in the presence of an Mg vapor at 900 °C. Preliminary results on films grown in situ by a high rate magnetron sputtering technique from stoichiometric MgB 2 and Mg targets are also reported. Microwave measurements have been carried out employing a dielectrically loaded niobium superconducting cavity operating at 19.8 GHz and 4 K. The study shows that the electrodynamic response of MgB 2 films is presently dominated by extrinsic sources of dissipation, appearing already at low microwave power, likely to be ascribed to the presence of grain boundaries and normal inclusions in the samples.

  1. Improving magnetic properties of MgB2 bulk superconductors by synthetic engine oil treatment

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Yanmaz, E.

    2016-08-01

    The present study focuses on the effects of standby time of the MgB2 samples immersed in synthetic engine oil on the critical current density (Jc(H)), magnetic field dependence of the pinning force density fp(b) and Tc performances of MgB2 bulk superconductors. Synthetic engine oil was used as a product which is cheap and a rich carbon source. Manufactured MgB2 pellet samples were immersed at different standby time of 30 min, 120 min, 300 min and 1440 min in synthetic engine oil after the first heating process. Finally, MgB2 samples immersed in synthetic engine oil were sintered at 1000 °C and kept for 15 min in Ar atmosphere. The critical current density of all of MgB2 samples immersed at different standby time in engine oil in whole field range was better than that of the pure MgB2 sample because of the number of the pinning centers. The MgB2 sample immersed at 300 min standby time in synthetic engine oil has the best performance compared to other samples. The Jc value for the pure sample is 2.0 × 103 A/cm2, whereas for the MgB2 sample immersed at 300 min standby time in engine oil the Jc is enhanced to 4.8 × 103A/cm2 at 5 K and 3 T. The superconducting transition temperature (Tc) did not change with the increasing standby time of the samples in synthetic engine oil at all. The best diamagnetic property was obtained from the sample which kept in synthetic engine oil for 300 min. Synthetic engine oil treatment results in remarkable improvement of the critical current density and pinning force performances of MgB2 superconductors. It was found that all MgB2 samples have a different pinning property at different measuring temperatures. Using synthetic engine oil as a product which is cheap and a rich carbon source in MgB2 bulk superconductors makes MgB2 samples immersed in synthetic engine oil a good candidate for industrial applications.

  2. Study of critical current density in superconducting magnesium diboride films grown by ex situ annealing of CVD boron films

    NASA Astrophysics Data System (ADS)

    Hanna, Mina

    MgB2 films have been processed by different techniques, the most successful of which include the hybrid physical-chemical vapor deposition (HPCVD) as well as the ex situ high temperature annealing of boron films in Mg vapor. The advantage of the ex situ method is that it allows the coating of MgB2 on large and complex surfaces, such as superconducting radio frequency (RF) cavities. However, it has always been realized that HPCVD films can carry higher J c than the ex situ annealed films. In this research, we succeeded in fabricating high quality MgB2 films by the ex situ annealing technique that produced a Jc value as high as 1.8 x 106 A/cm 2 for 1 mum thick film at 20 K and self-field. This high Jc value is, however, considerably reduced at higher thicknesses similar to that observed in YBCO coated conductors. In order to understand the mechanisms responsible for J c decrease with increasing film thickness, we studied the Jc behavior as a function of thickness in MgB2 films fabricated by ex situ annealing at 840°C of boron films, grown by chemical vapor deposition, in Mg vapor. The film thickness ranged between 300 nm and 10 mum. The values of Jc for these films ranged from 1.2 x 107 A/cm2 for 300 nm to 1.9 x 105 A/cm2 for 10 mum film thickness at 20 K and self-field. In addition, the results show that critical current (Ic) reaches a maximum value of 728 A/cm width at ˜1 mum thick MgB2 film at 20 K and self-field. These results of Jc and Ic behaviors with higher thickness are interpreted in terms of impurity diffusion during annealing and microstructural degradation for thicker films.

  3. Semiconductors: In Situ Processing of Photovoltaic Devices

    NASA Technical Reports Server (NTRS)

    Curreri, Peter A.

    1998-01-01

    The possible processing of semiconductor photovoltaic devices is discussed. The requirements for lunar PV cells is reviewed, and the key challenges involved in their manufacturing are investigated. A schematic diagram of a passivated emitter and rear cell (PERC) is presented. The possible fabrication of large photovoltaic arrays in space from lunar materials is also discussed.

  4. Connectivity, Doping, and Anisotropy in Highly Dense Magnesium Diboride (MgB2)

    NASA Astrophysics Data System (ADS)

    Li, Guangze

    Magnesium diboride (MgB2) is a superconducting material which can be potentially used in many applications such as magnetic resonance imaging system (MRI), wind turbine generators and high energy physics facilities. The major advantages of MgB2 over other superconductors include its relatively high critical temperature of about 39 K, its low cost of raw materials, its simple crystal structure, and its round multifilament form when in the form of superconducting wires. Over the past fourteen years, much effort has been made to develop MgB2 wires with excellent superconducting properties, particularly the critical current density J c. However, this research has been limited by technical difficulties such as high porosity and weak connectivity in MgB2, relatively small flux pinning strength, low upper critical field B c2 and relatively high anisotropy. The goal of this dissertation is to understand the relationship between superconducting properties, microstructure, and reaction mechanisms in MgB 2. In particular, the influences of connectivity, B c2, anisotropy and flux pinning were investigated in terms of the effects of these variables on the Jcs and n-values of MgB2 superconducting wires (n-value is a parameter which indicates the sharpness of resistive V-I transition). The n -values of traditional "Powder in Tube (PIT)" processed MgB2 wires were improved by optimizing precursor species after the identification of microstructural defects such as so-called "sausaging problems". Also, it was found that "high porosity and weak connectivity" was one of the most critical issues which limited the J c performance in typical MgB2. To overcome this problem, highly dense, well-connected MgB2 conductors were successfully fabricated by adopting an innovative "Advanced Internal Magnesium Infiltration (AIMI)" process. A careful study on the reaction kinetics together with the microstructural evidence demonstrated how the MgB2 layer was formed as the infiltration process

  5. 30 CFR 785.22 - In situ processing activities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false In situ processing activities. 785.22 Section 785.22 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY PROGRAMS REQUIREMENTS FOR PERMITS...

  6. Raman spectroscopy for in-situ monitoring of electrode processes

    SciTech Connect

    Varma, R; Cook, G M; Yao, N P

    1982-04-01

    The theoretical and experimental applications of Raman spectroscopic techniques to the study of battery electrode processes are described. In particular, the potential of Raman spectroscopy as an in-situ analytical tool for the characterization of the structure and composition of electrode surface layers at electrode-electrolyte interfaces during electrolysis is examined. It is anticipated that this understanding of the battery electrode processes will be helpful in designing battery active material with improved performance. The applications of Raman spectroscopy to the in-situ study of electrode processes has been demonstrated in a few selected areas, including: (1) the anodic corrosion of lead in sulfuric acid and (2) the anodization and sulfation of tetrabasicleadsulfate in sulfuric acid. Preliminary results on the anodization of iron and on the electrochemical behavior of nickel positive-electrode active material in potassium hydroxide electrolytes are presented in the Appendix.

  7. Heterostructures of Bi-4334 and MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Padmavathi, M.; Singh, R.

    2016-05-01

    We report the studies on hetero structures of Bi-4334 and MgB2 superconductors. The two superconductors were arranged in the form of bulk multilayers using hydraulic pressure system. X-ray diffraction pattern and dc magnetization studies confirm the presence of both superconducting phases in this try-layer hetero structured sample. The d.c magnetization shows the superconducting onset at 77K and 39K for Bi-4334 and MgB2 phases respectively. Critical current density (Jc) is calculated from hysteresis loop of the sample in both in-plane field and out of plane field configurations. Inverted anisotropy in Jc is observed due to enhancement of ab-plane properties because of multilayer growth process. Morphology of the samples at surface and interface of two superconducting layers is discussed in view of Field emission scanning electron microscopy.

  8. Evaluation of persistent-mode operation in a superconducting MgB2 coil in solid nitrogen

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; See, Khay Wai; Qiu, Wenbin; Kobayashi, Hiroki; Ma, Zongqing; Kim, Seong Jun; Hong, Jonggi; Park, Jin Yong; Choi, Seyong; Maeda, Minoru; Shahabuddin, Mohammed; Rindfleisch, Matt; Tomsic, Mike; Xue Dou, Shi; Kim, Jung Ho

    2016-04-01

    We report the fabrication of a magnesium diboride (MgB2) coil and evaluate its persistent-mode operation in a system cooled by a cryocooler with solid nitrogen (SN2) as a cooling medium. The main purpose of SN2 was to increase enthalpy of the cold mass. For this work, an in situ processed carbon-doped MgB2 wire was used. The coil was wound on a stainless steel former in a single layer (22 turns), with an inner diameter of 109 mm and height of 20 mm without any insulation. The two ends of the coil were then joined to make a persistent-current switch to obtain the persistent-current mode. After a heat treatment, the whole coil was installed in the SN2 chamber. During operation, the resultant total circuit resistance was estimated to be <7.4 × 10-14 Ω at 19.5 K ± 1.5 K, which meets the technical requirement for magnetic resonance imaging application.

  9. High density and connectivity of a MgB2 filament made using the internal magnesium diffusion technique

    NASA Astrophysics Data System (ADS)

    Kulich, M.; Kováč, P.; Hain, M.; Rosová, A.; Dobročka, E.

    2016-03-01

    In order to allow precise and detailed physical studies of an MgB2 filament made by the internal magnesium diffusion process (IMD), a modified approach (MIMD) using a Mg tube filled with boron powder deformed into wire was introduced. The MIMD process allows easy extraction of the MgB2 filament after the final heat treatment and performance of four-probe resistive measurements and density estimation, which is not possible for standard IMD wires. The Rowell approach has been applied for the grain connectivity from R(T) data of extracted MgB2 for the first time. The filament’s density has been estimated from the precise volume measured by x-ray micro-tomography and mass. The high connectivity and density of the MgB2 filament made by the diffusion process are discussed and compared with those of filaments made by other processes.

  10. Significant improvement of critical current density in MgB2 doped with ferromagnetic Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Qu, B.; Sun, X. D.; Li, J.-G.; Xiu, Z. M.; Liu, S. H.; Xue, C. P.

    2009-01-01

    Ferromagnetic Fe3O4-doped MgB2 bulks were first fabricated in this work by the hot pressing method. It was found that Fe3O4 does not react with Mg or B during the fabrication process. Peak Jc values of the 5 wt% Fe3O4-doped MgB2 are higher than 106 A cm-2 in the temperature range 5-30 K. Especially at 30 K, the peak Jc is 1.02 × 106 A cm-2 for the 5 wt% Fe3O4-doped MgB2, the highest values at 30 K found in the literature, and about seven times that of the 5 wt% SiC-doped MgB2 sample. The drop in Jc with increasing field for the Fe3O4-doped MgB2 is significantly slower than that of the SiC-doped MgB2 at 30 K. These results indicate that the Fe3O4-doped MgB2 is a potential superconductor to be used at temperatures greater than 25 K which is a critical temperature for large-scale practical applications.

  11. Influence of microstructures and crystalline defects on the superconductivity of MgB2

    NASA Astrophysics Data System (ADS)

    Serquis, A.; Liao, X. Z.; Zhu, Y. T.; Coulter, J. Y.; Huang, J. Y.; Willis, J. O.; Peterson, D. E.; Mueller, F. M.; Moreno, N. O.; Thompson, J. D.; Nesterenko, V. F.

    2002-07-01

    This work studies the influence of microstructures and crystalline defects on the superconductivity of MgB2, with the objective to improve its flux pinning. A MgB2 sample pellet that was hot isostatic pressed (HIPed) was found to have significantly increased critical current density (Jc) at higher fields than its un-HIPed counterpart. The HIPed sample had a Jc of 10 000 A/cm2 in 50 000 Oe (5 T) at 5 K. This was 20 times higher than that of the un-HIPed sample, and the same as the best Jc reported by other research groups. Microstructures observed in scanning and transmission electron microscopy indicate that the HIP process eliminated porosity present in the MgB2 pellet resulting in an improved intergrain connectivity. Such improvement in intergrain connectivity was believed to prevent the steep Jc drop with magnetic field H that occurred in the un-HIPed MgB2 pellet at H>45 000 Oe(4.5 T) and T=5 K. The HIP process was also found to disperse the MgO that existed at the grain boundaries of the un-HIPed MgB2 pellet and to generate more dislocations in the pellets. These dispersed MgO particles and dislocations improved flux pinning also at H<45 000 Oe. The HIPing process was also found to lower the resistivity at room temperature.

  12. Fine-Filament MgB2 Superconductor Wire

    NASA Technical Reports Server (NTRS)

    Cantu, Sherrie

    2015-01-01

    Hyper Tech Research, Inc., has developed fine-filament magnesium diboride (MgB2) superconductor wire for motors and generators used in turboelectric aircraft propulsion systems. In Phase I of the project, Hyper Tech demonstrated that MgB2 multifilament wires (<10 micrometers) could reduce alternating current (AC) losses that occur due to hysteresis, eddy currents, and coupling losses. The company refined a manufacturing method that incorporates a magnesium-infiltration process and provides a tenfold enhancement in critical current density over wire made by a conventional method involving magnesium-boron powder mixtures. Hyper Tech also improved its wire-drawing capability to fabricate fine multifilament strands. In Phase II, the company developed, manufactured, and tested the wire for superconductor and engineering current density and AC losses. Hyper Tech also fabricated MgB2 rotor coil packs for a superconducting generator. The ultimate goal is to enable low-cost, round, lightweight, low-AC-loss superconductors for motor and generator stator coils operating at 25 K in next-generation turboelectric aircraft propulsion systems.

  13. Development of the integrated in situ lasagna process

    SciTech Connect

    Ho, S.; Athmer, C.; Sheridan, P.

    1995-10-01

    Contamination in deep, low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in uniform delivery of treatment reagents have rendered existing in-situ methods such as bioremediation, vapor extraction, and pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites. Recently the use of electrokinetics as an in situ method for soil remediation has received increasing attention due to its unique applicability to low-permeability soils. Electrokinetics includes the transport of water (electroosmosis) as well as ions (electromigration) as a result of an applied electric field. For remedial applications, water is typically introduced into the soil at the anode to replenish the water flowing towards the cathode due to electroosmosis. The water flow is utilized to flush organic contaminants from the subsurface soil to the ground surface at the cathode region for further treatment or disposal. This report describes a treatment process under development termed the LASAGNA process which incorporates electrokinetics, along with the establishment of degradation zones, for pollutant removal.

  14. The phase analysis of spark plasma sintered MgB2 after ball milling.

    PubMed

    Kang, Deuk-Kyun; Kim, Dong-Woong; Kim, Cheol-Jin; Ahn, In-Shup

    2010-01-01

    Mg and amorphous B powders below 10 and 3 micro meter were used as raw materials, and mixed by planetary-mill for 9 hours at argon atmosphere. MgB2 bulk was fabricated at the various temperatures by Spark Plasma Sintering. In the sintering process, mixed powders were sintered in graphite mold, at the pressure of 55 Mpa. The fabricated MgB2 samples were evaluated with XRD, EDS, FE-SEM, PPMS. MgB2, MgO and Fe phases were observed from XRD result. In the results, MgO and Fe were impurity which may affect superconducting properties of MgB2 samples, and it's distribution could be confirmed from EDS mapping result. In order to confirm the formation of MgB2 phase, DTA was used as heating rate of 10 degrees C/min at Ar atmosphere from room temperature to 1200 degrees C. In the PPMS result, the Tc (critical temperature) was about 21 K, and the density of spark plasma sintered samples increased to 1.87 g/cm3 by increasing sintering temperature.

  15. Treatment of gas from an in situ conversion process

    SciTech Connect

    Diaz, Zaida; Del Paggio, Alan Anthony; Nair, Vijay; Roes, Augustinus Wilhelmus Maria

    2011-12-06

    A method of producing methane is described. The method includes providing formation fluid from a subsurface in situ conversion process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. At least the olefins in the first gas stream are contacted with a hydrogen source in the presence of one or more catalysts and steam to produce a second gas stream. The second gas stream is contacted with a hydrogen source in the presence of one or more additional catalysts to produce a third gas stream. The third gas stream includes methane.

  16. Compositions produced using an in situ heat treatment process

    DOEpatents

    Roes, Augustinus Wilhelmus Maria; Nair, Vijay; Munsterman, Erwin Henh; Van Bergen, Petrus Franciscus; Van Den Berg, Franciscus Gondulfus Antonius

    2009-10-20

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

  17. Compositions produced using an in situ heat treatment process

    DOEpatents

    Roes, Augustinus Wilhelmus Maria; Nair, Vijay; Munsterman, Erwin Hunh; Van Bergen, Petrus Franciscus; Van Den Berg, Franciscus Gondulfus Antonius

    2013-05-28

    Methods for treating a subsurface formation and compositions produced therefrom are described herein. At least one method for producing hydrocarbons from a subsurface formation includes providing heat to the subsurface formation using an in situ heat treatment process. One or more formation particles may be formed during heating of the subsurface formation. Fluid that includes hydrocarbons and the formation particles may be produced from the subsurface formation. The formation particles in the produced fluid may include cenospheres and have an average particle size of at least 0.5 micrometers.

  18. A defect detection method for MgB2 superconducting and iron-based Ba(Fe,Co)2As2 wires

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Morawski, A.; Zaleski, A.; Yamamoto, A.; Cetner, T.

    2016-04-01

    In this article, a method allowing for the detection of damage in iron-based superconducting bulks and MgB2 wires is presented. MgB2 wires were made of in situ material with ex situ MgB2 barrier. The iron superconductor studied was Ba(Fe,Co)2As2. This material was surrounded by Nb barrier and placed inside an iron tube. All samples were annealed in the isostatic pressure of 1 GPa. Transport measurements were made using a four-contact probe. The transition of Nb and ex situ MgB2 barrier from superconducting into resistive state (first transition) was observed at a temperature range from 5 K to 10 K and can be attributed to damage in either the Nb or ex situ MgB2 barrier in these samples. For samples with a damaged barrier, it was not possible to determine the critical current density of the wires. The analysis indicates that annealing at 1 GPa leads to the Ba(Fe,Co)2As2 material with critical temperatures of 27 K and 21.5 K at upper critical flux density (Bc2) of 14 T.

  19. Numerical modelling and comparison of MgB2 bulks fabricated by HIP and infiltration growth

    NASA Astrophysics Data System (ADS)

    Zou, J.; Ainslie, M. D.; Fujishiro, H.; Bhagurkar, A. G.; Naito, T.; Babu, N. Hari; Fagnard, J.-F.; Vanderbemden, P.; Yamamoto, A.

    2015-07-01

    MgB2 in bulk form shows great promise as trapped field magnets (TFMs) as an alternative to bulk (RE)BCO materials to replace permanent magnets in applications such as rotating machines, magnetic bearings and magnetic separation, and the relative ease of fabrication of MgB2 materials has enabled a number of different processing techniques to be developed. In this paper, a comparison is made between bulk MgB2 samples fabricated by the hot isostatic pressing (HIP), with and without Ti-doping, and infiltration growth (IG) methods and the highest trapped field in an IG-processed bulk MgB2 sample, Bz = 2.12 at 5 K and 1.66 T at 15 K, is reported. Since bulk MgB2 has a more homogeneous Jc distribution than (RE)BCO bulks, studies on such systems are made somewhat easier because simplified assumptions regarding the geometry and Jc distribution can be made, and a numerical simulation technique based on the 2D axisymmetric H-formulation is introduced to model the complete process of field cooling (FC) magnetization. As input data for the model, the measured Jc(B,T) characteristics of a single, small specimen taken from each bulk sample are used, in addition to measured specific heat and thermal conductivity data for the materials. The results of the simulation reproduce the experimental results extremely well: (1) indicating the samples have excellent homogeneity, and (2) validating the numerical model as a fast, accurate and powerful tool to investigate the trapped field profile of bulk MgB2 discs of any size accurately, under any specific operating conditions. Finally, the paper is concluded with a numerical analysis of the influence of the dimensions of the bulk sample on the trapped field.

  20. In situ ammonia analyzer for process control and environmental monitoring

    SciTech Connect

    Monlux, G.; Brand, J.A.; Zmarzly, P.

    1996-12-31

    An ammonia monitor designed for in situ smoke stack or exhaust duct applications is discussed here. A probe composed of a diffusion cell with a protected multipass optical measurement cavity provides the optical interaction with the sample. Other components of the system include signal processing electronics and an embedded PC104 computer platform. This instrument is useful in a wide variety of ammonia monitoring and process control applications, particularly ammonia-based NO{sub x} control technologies, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). The in situ design eliminates sample handling problems, associated with extractive analysis of ammonia, such as sample line adsorption and heated sample trains and cells. The sensor technology exploited in this instrument is second harmonic spectroscopy using a near infrared diode laser. Data collected during field trials involving both SCR and SNCR applications demonstrate the feasibility and robust operation of this instrument in traditionally problematic operating environments. The instrument can measure other gases by changing the wavelength, either by changing the diode operational set point or by changing the diode. In addition, with straightforward modification the instrument can measure multiple species.

  1. A study on the nonlinear microwave electrodynamic response of e-beam evaporated MgB2 superconducting thin films

    NASA Astrophysics Data System (ADS)

    Andreone, A.; Di Gennaro, E.; Lamura, G.; Salluzzo, M.; Purnell, A.; Cohen, L. F.; Hao, L.; Gallop, J.; Cantoni, C.; Paranthaman, M.

    2003-02-01

    We present a study on the temperature and field dependence of the microwave surface impedance Zs in thin films of the superconducting MgB2 compound. Samples were prepared by e-beam evaporation of boron on r-plane sapphire followed by an ex situ annealing in Mg vapour. Critical temperature values range between 26 and 38 K. Surface impedance measurements (Zs = Rs + iXs) were performed from 2 K close to Tc in the microwave region up to 20 GHz via parallel plate or dielectrically loaded resonators in 'symmetric' (two MgB2 films) and asymmetric (an MgB2 film and a commercial YBCO control film) configurations. At high microwave power, frequency domain measurements show a characteristic signature associated with weak links and this appears to be the limiting factor governing the performance of these films.

  2. In situ studies of microbial inactivation during high pressure processing

    NASA Astrophysics Data System (ADS)

    Maldonado, Jose Antonio; Schaffner, Donald W.; Cuitiño, Alberto M.; Karwe, Mukund V.

    2016-01-01

    High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization.

  3. Temperature effect on microstructure and electromagnetic performance of polycarbosilane and sugar-doped MgB2 wires

    NASA Astrophysics Data System (ADS)

    Shcherbakov, A. V.; Horvat, J.; Shcherbakova, O. V.; Novosel, N.; Babić, E.; Dou, S. X.

    2010-06-01

    The effect of processing temperature on structural and superconducting properties of 10 wt.% sugar- and 10 wt.% PCS-doped MgB2 wires is systematically investigated. It is demonstrated that these dopants significantly enhance the electromagnetic performance of Fe-clad MgB2 superconductor and increase its potential for practical application. The enhancement of in-field critical current density (Jc(Ba)) and upper critical field (Bc2) is due to formation of a large amount of lattice defects caused by impurities and C substitution into the MgB2 crystal lattice. High temperature sintering of sugar-doped sample results in as high Bc2 value as 37 T (at 5 K), which correlates with higher level of C substitution into MgB2 crystal lattice in this sample. In contrast, for PCS doped MgB2 wire higher Bc2 value (32 T at 5 K) is observed at lower sintering temperatures. In spite of the fact that the level of C in the crystal lattice and Bc2 value are higher in the sugar doped MgB2 sample, this sample has lower Jc(Ba) when compared to the sample with PCS addition. We speculate that it is due to a higher level of MgO impurities in the sugar doped sample (18.6 wt.% compared to 9.15 wt.% in the PCS doped sample), which results in the dissipation of supercurrent flowing through this sample.

  4. Neutron irradiation of MgB2 bulk superconductors

    SciTech Connect

    Eisterer, M; Zehetmayer, M; Tonies, S; Weber, H W.; Kambara, M; Babu, N H.; Cardwell, D A.; Greenwood, Lawrence R. )

    2001-12-01

    Sintered samples of MgB2 were irradiated in a fission reactor. Defects in the bulk microstructure are produced during this process mainly by the 10B(n,a7Li) reaction while collisions of fast neutrons with the lattice atoms induce much less damage. Self-shielding effects turn out to be very important and lead to a highly inhomogeneous defect distribution in the irradiated samples. The resulting disorder enhances the normal state resistivity and the upper critical field. The irreversibility line shifts to higher fields at low temperatures and the measured critical current densities increase following irradiation.

  5. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  6. Superior critical current density obtained in MgB2 bulks via employing carbon-coated boron and minor Cu addition

    NASA Astrophysics Data System (ADS)

    Peng, Junming; Liu, Yongchang; Ma, Zongqing; Shahriar Al Hossain, M.; Xin, Ying; Jin, Jianxun

    2016-09-01

    High performance Cu doped MgB2 bulks were prepared by an in-situ method with carbon-coated amorphous boron as precursor. It was found that the usage of carbon-coated boron in present work leads to the formation of uniformly refined MgB2 grains, as well as a high level of homogeneous carbon doping in the MgB2 samples, which significantly enhance the Jc in both Cu doped and undoped bulks compared to MgB2 bulks with normal amorphous boron precursor. Moreover, minor Cu can service as activator, and thus facilitates the growth of MgB2 grains and improves crystallinity and grain connectivity, which can bring about the excellent critical current density (Jc) at self fields and low fields (the best values are 7 × 105 A/cm2 at self fields, and 1 × 105 A/cm2 at 2 T, 20 K, respectively). Simultaneously, minor Cu addition can reduce the amount of MgO impurity significantly, also contributing to the improvement of Jc at low fields. Our work suggests that Cu-activated sintering combined with employment of carbon-coated amorphous boron as precursor could be a promising technique to produce practical MgB2 bulks or wires with excellent Jc on an industrial scale.

  7. Energy from true in situ processing of antrim shale: process control and data collection

    SciTech Connect

    Frost, J.R.; Pihlaja, R.K.

    1980-07-01

    This report describes the process control and ancillary operating equipment used at the Antrim shale in situ field extraction trials. A method of flame detection for well heaters is described. An automated method of data logging procedures, final data collection method, and data reduction procedures used during these trials is presented.

  8. Energy from true in situ processing of Antrim oil shale: initial in situ extraction trials

    SciTech Connect

    McNamara, P.H.

    1980-04-01

    This report covers the three in situ extraction trials performed at The Dow Chemical Company's existing oil shale site near Peck, Michigan, from August 11, 1977 to May 24, 1978 and the subsequent analysis. The trials were conducted at a depth of 1200 to 1300 feet for a total operating time of 109 days. Ignition was achieved by an electric heater and by a propane burner using coal and charcoal to increase the input of energy. Gas having an energy value of 50 to 55 Btu/scf was prodcued. The energy recovered in the third and most productive trial compared to the energy used for ignition reached a ratio of 4.8. A cyclic operation, called Huff and Puff, gave a 47 to 65% improvement in energy recovery compared to a single forward combustion. No sulfur compounds were detected in the production gas. Particulate measurement was not of value in monitoring the burning process. The trials reported, and the information gathered for them, provide a basis for a trial at a new site adjacent to the existing site.

  9. Preparation and characterization of Sc doped MgB2 wires

    NASA Astrophysics Data System (ADS)

    Grivel, J.-C.; Burdusel, M.

    2016-09-01

    The in-situ technique was used to manufacture scandium (Sc) doped MgB2 wires in a composite Cu-Nb sheath. After reaction at 700 °C, at most 1 at.% Mg was replaced by Sc in the MgB2 phase, without significant influence on its superconducting transition temperature. For higher Sc concentrations in the nominal composition, the formation of Sc-rich impurity phases was evidenced by SEM/EDS observations. The critical current density and accommodation field of the wires are weakly dependant on the Sc content. It is believed that these effects are related more to modifications of the thermal behaviour of the precursor powders revealed by DTA measurements than to actual doping. The best performance was obtained in a wire with Mg:Sc = 0.995_0.005 atomic ratio.

  10. Enhancement of critical current density of MgB2 by doping Ho2O3

    NASA Astrophysics Data System (ADS)

    Cheng, C.; Zhao, Y.

    2006-12-01

    Mg1-x(Ho2O3)xB2 alloys were prepared by in situ solid state reaction to study the effect of magnetic Ho2O3 dopant on flux pinning behavior of MgB2. Crystal structure, Tc, and Hc2 were not affected by Ho2O3 doping; however, Jc and Hirr were significantly enhanced. In 5T field, the best sample (x =3%) reached Jc of 1.0×103, 2.0×104, and 1.2×105A/cm2 at 20, 10, and 5K, respectively, much higher than those achieved by nonmagnetic impurity, such as Ti-, Zr-, and Y2O3-doped MgB2. The observed magnetic HoB4 nanoparticles were attributed to be the source for the enhanced flux pinning effects.

  11. Modeling of the in-situ vitrification process

    SciTech Connect

    Koegler, S.S.; Kindle, C.H.

    1990-04-01

    In situ vitrification (ISV) is a thermal treatment process that converts contaminated soil into a durable, leach-resistant product similar to obsidian or basalt. The process, which was developed by Pacific Northwest Laboratory (PNL) for remediation of contaminated soil, is now in the field demonstration and implementation stage. Demonstration tests using the US Department of Energy (DOE)-owned large-scale system are underweight or planned for applications at Hanford and other DOE sites, including the Idaho National Engineering Laboratory, Oak Ridge National Laboratory, and the Savannah River Site. In addition, a private company, Geosafe Corporation, is beginning remediation of commercial contaminated soil sites. A mathematical and computer model has been developed at PNL as a predictive tool to assist engineers and researchers in the application of ISV to different sites. The model, currently configured on a Macintosh personal computer, predicts vitrification time, depth, width, and electrical consumption based on user inputs of electrode configuration, soil parameters, and molten glass characteristics. The model time and depth predications are useful for operations planning, cost estimates, and site selection. Additionally, the depth and width predictions will be used to direct ISV operations to ensure that the contaminated area is completely vitrified and to help mitigate the effect of ISV on adjacent structures. 1 ref., 8 figs.

  12. Development of the integrated in situ Lasagna process

    SciTech Connect

    Ho, S.; Athmer, C.; Sheridan, P.

    1995-12-31

    Contamination in deep, low permeability soils poses a significant technical challenge to in-situ remediation efforts. Poor accessibility to the contaminants and difficulty in uniform delivery of treatment reagents have rendered existing in-situ methods such as bioremediation, vapor extraction, and pump and treat rather ineffective when applied to low permeability soils present at many contaminated sites.

  13. In situ remediation process using divalent metal cations

    DOEpatents

    Brady, Patrick V.; Khandaker, Nadim R.; Krumhansl, James L.; Teter, David M.

    2004-12-14

    An in situ process for treating ambient solid materials (e.g., soils, aquifer solids, sludges) by adding one or more divalent metal cations to the ambient solid material. The added divalent metal cations, such as Cu.sup.2+ or Zn.sup.2+, combine with metal oxide/hydroxides (e.g., ferric oxide/hydroxide or aluminum oxide/hydroxide) already present in the ambient solid material to form an effective sorbent material having a large number of positively-charged surface complexes that binds and immobilizes anionic contaminant species (e.g., arsenic or chromate). Divalent metal cations can be added, for example, by injecting an aqueous solution of CuSO.sub.4 into an aquifer contaminated with arsenic or chromate. Also, sludges can be stabilized against leaching of anionic contaminants through the addition of divalent metal cations. Also, an inexpensive sorbent material can be easily formed by mixing divalent metal cations with soil that has been removed from the ground.

  14. The Development of In-Situ Ion Implant Cleaning Processes

    NASA Astrophysics Data System (ADS)

    Bishop, Steve; Kaim, Robert; Yedave, Sharad; Arnó, Josep; DiMeo, Frank; Wodjenski, Mike

    2006-11-01

    Considerable gains in implanter utilization efficiency can be attained with in-situ cleaning of deposited material, particularly in and around the ion source. Different methods of in-situ cleaning are described, and we discuss the relative merits of several chemical reagents. We introduce XeF2, a new and promising reagent for in-situ cleaning and present some preliminary experiments showing its ability to etch dopant materials. We also show that in some cases etching by XeF2 can be selective with respect to ion source construction materials such as tungsten.

  15. Reactive spark plasma sintering of MgB2 in nitrogen atmosphere for the enhancement of the high-field critical current density

    NASA Astrophysics Data System (ADS)

    Badica, P.; Burdusel, M.; Popa, S.; Pasuk, I.; Ivan, I.; Borodianska, H.; Vasylkiv, O.; Kuncser, A.; Ionescu, A. M.; Miu, L.; Aldica, G.

    2016-10-01

    High density bulks (97%-99%) of MgB2 were prepared by spark plasma sintering (SPS) in nitrogen (N2) atmosphere for different heating rates (10, 20 and 100 °C min-1) and compared with reference samples processed in vacuum and Ar. N2 reacts with MgB2 and forms MgB9N along the MgB2 grain boundaries. The high-field critical current density is enhanced for the sample processed in N2 with a heating rate of 100 °C min-1. At 2-35 K, this sample shows the strongest contribution of the grain boundary pinning (GBP). All samples are in the point pinning (PP) limit and by increasing temperature the GBP contribution decreases.

  16. In situ characterization of nanoscale catalysts during anodic redox processes

    SciTech Connect

    Sharma, Renu; Crozier, Peter; Adams, James

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  17. Gas injection to inhibit migration during an in situ heat treatment process

    DOEpatents

    Kuhlman, Myron Ira; Vinegar; Harold J.; Baker, Ralph Sterman; Heron, Goren

    2010-11-30

    Methods of treating a subsurface formation are described herein. Methods for treating a subsurface treatment area in a formation may include introducing a fluid into the formation from a plurality of wells offset from a treatment area of an in situ heat treatment process to inhibit outward migration of formation fluid from the in situ heat treatment process.

  18. Second-phase segregation and micro strain/lattice parameter dependent transition temperature in polycrystalline MgB2

    NASA Astrophysics Data System (ADS)

    Cai, Qi; Liu, Yongchang; Guo, Qianying; Ma, Zongqing; Li, Huijun

    2016-10-01

    Un-doped, metal-doped, and carbon-doped MgB2 samples were prepared by furnace cooling and quenching to investigate the second phase behavior and the resultant critical current density J c performance under different heat treatment processes, which is infrequently mentioned, and to explore the strain/lattice parameter dependence of the superconducting transition temperature. To release the residual stress, quenching induced second-phase segregation in these MgB2 samples shows a negative effect on the J c. Nevertheless, the dislocations and the lattice distortion assisted the enhancement of the high-field J c in the un-doped and metal-doped MgB2 samples, which indicated that quenching could be technically applied for the fabrication of metal-sheathed MgB2 wires and tapes to obtain excellent J c. After evaluating the micro strain and the lattice parameters’ (c and a for hexagonal lattice) variation, a dome was observed in the illustration of the strain/lattice parameter c/a dependence of T c, which differed from the reported linear relation in previous work. This suggests that the c/a ratio and the strain may be the predominant parameters for scaling of the superconducting dome width in the superconducting phase diagram of MgB2.

  19. SITE TECHNOLOGY CAPSULE: IN SITU STEAM ENHANCED RECOVERY PROCESS

    EPA Science Inventory

    The SERP technology is designed to treat soils contaminated with VOCs and SVOCs in situ. Steam injection and vacuum extraction are used to remove the organic compounds from the soil and concentrate them for disposal or recycling. A full-scale demonstration of SERP was conducted a...

  20. Mechanism of enhancement in electromagnetic properties of MgB2 by Nano SiC doping.

    PubMed

    Dou, S X; Shcherbakova, O; Yeoh, W K; Yoeh, W K; Kim, J H; Soltanian, S; Wang, X L; Senatore, C; Flukiger, R; Dhalle, M; Husnjak, O; Babic, E

    2007-03-01

    A comparative study of pure, SiC, and C doped MgB2 wires has revealed that the SiC doping allowed C substitution and MgB2 formation to take place simultaneously at low temperatures. C substitution enhances H_{c2}, while the defects, small grain size, and nanoinclusions induced by C incorporation and low-temperature processing are responsible for the improvement in J_{c}. The irreversibility field (H_{irr}) for the SiC doped sample reached the benchmarking value of 10 T at 20 K, exceeding that of NbTi at 4.2 K. This dual reaction model also enables us to predict desirable dopants for enhancing the performance properties of MgB2.

  1. Evaluation of Select Surface Processing Techniques for In Situ Application During the Additive Manufacturing Build Process

    NASA Astrophysics Data System (ADS)

    Book, Todd A.; Sangid, Michael D.

    2016-07-01

    Although additive manufacturing offers numerous performance advantages for different applications, it is not being used for critical applications due to uncertainties in structural integrity as a result of innate process variability and defects. To minimize uncertainty, the current approach relies on the concurrent utilization of process monitoring, post-processing, and non-destructive inspection in addition to an extensive material qualification process. This paper examines an alternative approach by evaluating the application of select surface process techniques, to include sliding severe plastic deformation (SPD) and fine particle shot peening, on direct metal laser sintering-produced AlSi10Mg materials. Each surface processing technique is compared to baseline as-built and post-processed samples as a proof of concept for surface enhancement. Initial results pairing sliding SPD with the manufacture's recommended thermal stress relief cycle demonstrated uniform recrystallization of the microstructure, resulting in a more homogeneous distribution of strain among the microstructure than as-built or post-processed conditions. This result demonstrates the potential for the in situ application of various surface processing techniques during the layerwise direct metal laser sintering build process.

  2. Method of rubblization for in-situ oil shale processing

    NASA Technical Reports Server (NTRS)

    Yang, Lien C. (Inventor)

    1985-01-01

    A method that produces a uniformly rubblized oil shale bed of desirable porosity for underground, in-situ heat extraction of oil. Rubblization is the generation of rubble of various sized fragments. The method uses explosive loadings lying at different levels in adjacent holes and detonation of the explosives at different levels in sequence to achieve the fracturing and the subsequent expansion of the fractured oil shale into excavated rooms both above and below the hole pattern.

  3. RT-PCR for mammaglobin genes, MGB1 and MGB2, identifies breast cancer micrometastases in sentinel lymph nodes.

    PubMed

    Ouellette, Rodney J; Richard, Dominique; Maïcas, Emmanuel

    2004-05-01

    In the present study, we examined the expression of the mammaglobin genes, MGB1 and MGB2, in the sentinel lymph nodes (SLNs) of patients with breast cancer and compared our results with the histologic status of the same SLNs. Compared with immunohistochemical staining for cytokeratin 8, which detected metastases in 17 of 42 patients, reverse transcription-polymerase chain reaction (RT-PCR) for MGB1 or MGB2 genes was positive in 22 patients. The concordance between the expression of any mammaglobin and histologic status was 79% (33/42), with a sensitivity of 88% and specificity of 72%. The detection of patients with metastases was more sensitive when testing for both MGB1 and MGB2 (P < .0001) rather than MGB2 (P < .0005) or MGB1 (P < .05) alone. The increased detection rate relative to histologic examination suggests that using RT-PCR for the mammaglobin genes might identify patients at higher risk compared with patients with negative RT-PCR results.

  4. Effects of Bi-2212 addition on the levitation force properties of bulk MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Taylan Koparan, E.; Savaskan, B.; Guner, S. B.; Celik, S.

    2016-02-01

    We present a detailed investigation of the effects of Bi2Sr2Ca1Cu2O8+κ (Bi-2212) adding on the levitation force and magnetic properties of bulk MgB2 obtained by hot press method. The amount of Bi-2212 was varied between 0 and 10 wt% (0, 2, 4, 6, 10 wt%) of the total MgB2. Moreover, we present MgB2 bulk samples fabricated by using different production methods including hot pressing method to our knowledge. All samples were prepared by using elemental magnesium (Mg) powder, amorphous nano-boron (B) powder and Bi-2212 powder which are produced by hot press method. As a result of hot press process, compact pellet samples were manufactured. The vertical and lateral levitation force measurements were executed at the temperatures of 20, 24 and 28 K under zero-field-cooled (ZFC) and field-cooled (FC) regimes for samples with various adding levels. At 24 K and 28 K under ZFC regime, the 2 wt% Bi-2212 added sample exhibits a higher vertical levitation force than the pure sample. Bi-2212 added MgB2 samples compared to the pure sample have lower attractive force values in FC regime. The magnetic field dependence of the critical current density J c was calculated from the M-H loops for Bi-2212 added MgB2 samples. The 2 wt% Bi-2212 added sample has the best levitation and critical current density performance compared to other samples. The critical temperature ( T c ) has slightly dropped from 37.8 K for the pure MgB2 sample to 36.7 K for the 10 wt% of Bi-2212 added sample. The transition temperature slightly decreases when Bi-2212 adding level is increased.

  5. IN SITU STEAM ENHANCED RECOVERY PROCESS - HUGHES ENVIRONMENTAL SYSTEMS, INC. - INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    This Innovative Technology Evaluation report summarizes the findings of an evaluation of the in situ Steam Enhanced Recovery Process (SERP) operated by Hughes Environmental Systems, Inc. at the Rainbow Disposal facility in Huntington Beach, California. he technology demonstration...

  6. Sensor-model in-situ control of the RTM composite process

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.; Williamson, A.; Loos, A. C.

    1991-01-01

    The paper reports on the use of in situ frequency dependent electromagnetic sensors (FDEMS) and the Loos resin transfer model to select and control the processing properties of an epoxy resin during RTM impregnation and cure. Once correlated with viscosity and degree of cure, FDEMS monitors the advancement of the resin, viscosity, and the impregnation of the fabric, allowing a direct means of monitoring in situ in the mold throughout the fabrication process the effects of time, temperature, vacuum, and pressure.

  7. An evaluation of in-situ bioremediation processes

    SciTech Connect

    Cole, L.L.; Rashidi, M.

    1996-08-01

    Remediation of petroleum hydrocarbons in groundwater was the primary focus in the initial application of in-situ bioremediation which, from its development in the 1970s, has grown to become one of the most promising technologies for the degradation of a wide variety of organic contaminants. The degradation of contaminants in subsurface soils is the current new focus of the technology. While the need for improvements in the technology does exist, the indisputable fact remains that this technology is by far the least expensive and that it has the capability to provide long term reduced levels of contaminants or long term complete remediation of contaminated sites. The aim of this paper is to disclose pertinent information related to current conditions and current feelings in the area of new research, novel applications, new government regulations, and an overview of new topics on the horizon that relate to the overall technology.

  8. In situ conversion process utilizing a closed loop heating system

    SciTech Connect

    Sandberg, Chester Ledlie; Fowler, Thomas David; Vinegar, Harold J.; Schoeber, Willen Jan Antoon Henri

    2009-08-18

    An in situ conversion system for producing hydrocarbons from a subsurface formation is described. The system includes a plurality of u-shaped wellbores in the formation. Piping is positioned in at least two of the u-shaped wellbores. A fluid circulation system is coupled to the piping. The fluid circulation system is configured to circulate hot heat transfer fluid through at least a portion of the piping to form at least one heated portion of the formation. An electrical power supply is configured to provide electrical current to at least a portion of the piping located below an overburden in the formation to resistively heat at least a portion of the piping. Heat transfers from the piping to the formation.

  9. An integrated numerical and physical modeling system for an enhanced in situ bioremediation process.

    PubMed

    Huang, Y F; Huang, G H; Wang, G Q; Lin, Q G; Chakma, A

    2006-12-01

    Groundwater contamination due to releases of petroleum products is a major environmental concern in many urban districts and industrial zones. Over the past years, a few studies were undertaken to address in situ bioremediation processes coupled with contaminant transport in two- or three-dimensional domains. However, they were concentrated on natural attenuation processes for petroleum contaminants or enhanced in situ bioremediation processes in laboratory columns. In this study, an integrated numerical and physical modeling system is developed for simulating an enhanced in situ biodegradation (EISB) process coupled with three-dimensional multiphase multicomponent flow and transport simulation in a multi-dimensional pilot-scale physical model. The designed pilot-scale physical model is effective in tackling natural attenuation and EISB processes for site remediation. The simulation results demonstrate that the developed system is effective in modeling the EISB process, and can thus be used for investigating the effects of various uncertainties.

  10. Kinematic analysis of in situ measurement during chemical mechanical planarization process.

    PubMed

    Li, Hongkai; Wang, Tongqing; Zhao, Qian; Meng, Yonggang; Lu, Xinchun

    2015-10-01

    Chemical mechanical planarization (CMP) is the most widely used planarization technique in semiconductor manufacturing presently. With the aid of in situ measurement technology, CMP tools can achieve good performance and stable productivity. However, the in situ measurement has remained unexplored from a kinematic standpoint. The available related resources for the kinematic analysis are very limited due to the complexity and technical secret. In this paper, a comprehensive kinematic analysis of in situ measurement is provided, including the analysis model, the measurement trajectory, and the measurement time of each zone of wafer surface during the practical CMP process. In addition, a lot of numerical calculations are performed to study the influences of main parameters on the measurement trajectory and the measurement velocity variation of the probe during the measurement process. All the efforts are expected to improve the in situ measurement system and promote the advancement in CMP control system.

  11. Kinematic analysis of in situ measurement during chemical mechanical planarization process

    SciTech Connect

    Li, Hongkai; Wang, Tongqing; Zhao, Qian; Meng, Yonggang; Lu, Xinchun

    2015-10-15

    Chemical mechanical planarization (CMP) is the most widely used planarization technique in semiconductor manufacturing presently. With the aid of in situ measurement technology, CMP tools can achieve good performance and stable productivity. However, the in situ measurement has remained unexplored from a kinematic standpoint. The available related resources for the kinematic analysis are very limited due to the complexity and technical secret. In this paper, a comprehensive kinematic analysis of in situ measurement is provided, including the analysis model, the measurement trajectory, and the measurement time of each zone of wafer surface during the practical CMP process. In addition, a lot of numerical calculations are performed to study the influences of main parameters on the measurement trajectory and the measurement velocity variation of the probe during the measurement process. All the efforts are expected to improve the in situ measurement system and promote the advancement in CMP control system.

  12. SIMULATING THE IN SITU CONDENSATION PROCESS OF SOLAR PROMINENCES

    SciTech Connect

    Xia, C.; Keppens, R.; Antolin, P.; Porth, O.

    2014-09-10

    Prominences in the solar corona are a hundredfold cooler and denser than their surroundings, with a total mass of 10{sup 13} up to 10{sup 15} g. Here, we report on the first comprehensive simulations of three-dimensional, thermally and gravitationally stratified magnetic flux ropes where in situ condensation to a prominence occurs due to radiative losses. After a gradual thermodynamic adjustment, we witness a phase where runaway cooling occurs while counter-streaming shearing flows drain off mass along helical field lines. After this drainage, a prominence-like condensation resides in concave upward field regions, and this prominence retains its overall characteristics for more than two hours. While condensing, the prominence establishes a prominence-corona transition region where magnetic field-aligned thermal conduction is operative during the runaway cooling. The prominence structure represents a force-balanced state in a helical flux rope. The simulated condensation demonstrates a right-bearing barb, as a remnant of the drainage. Synthetic images at extreme ultraviolet wavelengths follow the onset of the condensation, and confirm the appearance of horns and a three-part structure for the stable prominence state, as often seen in erupting prominences. This naturally explains recent Solar Dynamics Observatory views with the Atmospheric Imaging Assembly on prominences in coronal cavities demonstrating horns.

  13. Simulating the in Situ Condensation Process of Solar Prominences

    NASA Astrophysics Data System (ADS)

    Xia, C.; Keppens, R.; Antolin, P.; Porth, O.

    2014-09-01

    Prominences in the solar corona are a hundredfold cooler and denser than their surroundings, with a total mass of 1013 up to 1015 g. Here, we report on the first comprehensive simulations of three-dimensional, thermally and gravitationally stratified magnetic flux ropes where in situ condensation to a prominence occurs due to radiative losses. After a gradual thermodynamic adjustment, we witness a phase where runaway cooling occurs while counter-streaming shearing flows drain off mass along helical field lines. After this drainage, a prominence-like condensation resides in concave upward field regions, and this prominence retains its overall characteristics for more than two hours. While condensing, the prominence establishes a prominence-corona transition region where magnetic field-aligned thermal conduction is operative during the runaway cooling. The prominence structure represents a force-balanced state in a helical flux rope. The simulated condensation demonstrates a right-bearing barb, as a remnant of the drainage. Synthetic images at extreme ultraviolet wavelengths follow the onset of the condensation, and confirm the appearance of horns and a three-part structure for the stable prominence state, as often seen in erupting prominences. This naturally explains recent Solar Dynamics Observatory views with the Atmospheric Imaging Assembly on prominences in coronal cavities demonstrating horns.

  14. Large MgB2 Superconducting Coils for the Ignitor Experiment

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Grasso, G.; Coppi, B.

    2012-10-01

    Intermediate temperature, superconducting cables have been adopted for the fabrication of the largest poloidal field coils of the Ignitor experiment. This is an important step to achieve better duty cycles in Ignitor-like machines with innovative magnet technologies compared to traditional superconductors. The commercially available MgB2 strands manufactured by Columbus Superconductors meets the target specifications for the considered coils, about 5 meters of outer diameter and maximum field on the conductor below 5 T, and they are also compatible with the Ignitor cryogenic system, which is designed to cool the machine at 30 K, although MgB2 may use colder gas at 10 K. The technical feasibility of these coils, as well as their stability and protection in the unlikely case of its quench, has been studied. The final design includes about 300 MgB2 multifilamentary strands of 1 mm in diameter and a copper pipe for the He-gas flow in the center. A mock-up cable has been manufactured. Measurements of the critical current Jc as a function of magnetic field and temperature have been done for the cable bent to a curvature radius of 20 cm and compared to the results of a straight sample. The feasability of the manufacturing and jacketing processes has thus been demonstrated.

  15. Influence of nanocrystalline boron precursor powder on superconductivity in MgB2 bulk.

    PubMed

    Zhang, Yun; Lu, Cheng; Zhou, Sihai; Joo, Jinho

    2009-12-01

    In this report, high-purity nanocrystalline boron powders processed by ball-milling were used as the precursor powders to fabricate MgB2 superconductor. The transport properties and the critical current density in the samples made from ball-milled boron powders and as-supplied boron powders were investigated. It was found that the ball-milled boron powders led to a significant enhancement of the critical current density in MgB2 sintered at 650 degrees C. The reason can be attributed to the small MgB2 grain size caused by the ball-milled boron precursor powders. The resistivity of the samples made from the ball-milled boron powder was lower than that of the sample from as-supplied boron powder. As the sintering temperature increased, both resistivity and upper critical field decreased in the samples using the ball-milled boron powders as a precursor. Poor connectivity and large strain are responsible for the high resistivity.

  16. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-07-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  17. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure.

    PubMed

    Yang, Y; Sumption, M D; Collings, E W

    2016-07-13

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  18. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    PubMed Central

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-01-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning. PMID:27406904

  19. Wireless sensor technology for in-situ plasma process monitoring

    NASA Astrophysics Data System (ADS)

    Gahan, David

    2015-09-01

    There is an increasing demand for plasma measurement and control solutions to cope with the growing complexity of integrated circuit manufacture in the semiconductor industry. Standard plasma diagnostic instruments used in research, such as the Langmuir probe, are not suitable for use in the production environment for myriad reasons - contamination of the process being one of the main concerns. Silicon wafer based wireless sensors, which measure temperature during the process, have gained the most traction with tool manufacturers and chip makers - albeit during process development or the PM cycle rather than live production. In this presentation we will discuss two novel wireless technologies that have the potential for use in process tools. The first is an ion detector embedded in a silicon wafer. The sensor measures the average ion flux and the maximum ion energy during the process. This information is stored and is downloaded later for analysis. The second technology consists of a wireless sensor that sits inside the process and communicates data in real time to a detector installed on the rf power line. This platform is similar to RFID technology and can be combined with various sensor types to transmit data to the user during the process.

  20. Process control of MOCVD growth for LEDs by in-situ photoluminescence

    NASA Astrophysics Data System (ADS)

    Prall, C.; Haberland, K.; Kaspari, C.; Brunner, F.; Weyers, M.; Rueter, D.

    2016-03-01

    Development and manufacturing of LED structures is still driven by production cost reduction and performance improvements. Therefore, in-situ monitoring during the epitaxial process plays a key role in view of further yield improvement and process optimization. With the continuing trend towards larger wafers, stronger bow and increased aspherical curvature are additional challenges the growers have to face, leading to non-uniform LED-emission. Compared to traditional in-situ metrology like curvature measurement and near UV pyrometry, in-situ photoluminescence measurements can provide a more direct access to the quantum well emission already during growth. In this paper we show how in-situ photoluminescence measurements can be used in a production type multi-wafer MOCVD system to characterize the quantum well emission already during growth. We also demonstrate how deviations from the desired wavelength can be detected and corrected in the same growth run. Since the method is providing spatially resolved line-scans across the wafer, also the uniformity of the emission wavelength can be characterized already during growth. Comparison of in-situ and ex-situ photoluminescence data show excellent agreement with respect to wavelength uniformity on 4 inch wafers.

  1. Experimental Investigation and High Resolution Simulator of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2006-12-31

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this current and thirteenth report, we report on our continuing development of a Virtual Kinetic Cell model and our continuing experimental program.

  2. EARTH TECH INC.'S ENHANCED IN-SITU BIOREMEDIATION PROCESS; INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    The USEPA conducted an evaluation of the Enhanced In-situ Bioremediation process, a biostimulation technology developed by the USDOE at the Westinghouse Savannah River Plant site in Aiken, SC. DOE has licensed the process to Earth Tech, Inc. The evaluation described in this bulle...

  3. SITE DEMONSTRATION BULLETIN - ENHANCED IN-SITU BIOREMEDIATION PROCESS, EARTH TECH, INC.

    EPA Science Inventory

    The USEPA conducted an evaluation of the Enhanced In-situ Bioremediation process, a biostimulation technology developed by the USDOE at the Westinghouse Savannah River Plant site in Aiken, SC. DOE has licensed the process to Earth Tech, Inc. The evaluation described in this bulle...

  4. EPA SITE DEMONSTRATION OF THE INTERNATIONAL WASTE TECHNOLOGIES/GEO-CON IN SITU STABILIZATION/ SOLIDIFICATION PROCESS

    EPA Science Inventory

    This paper presents an EPA evaluation of the first field demonstration of an in situ stabilization/solidification process for contaminated soil under the EPA Superfund Innovative Technology Evaluation (SITE) program. Demonstration of this process was a joint effort of two vendors...

  5. Superconductivity in dense MgB2 wires.

    PubMed

    Canfield, P C; Finnemore, D K; Bud'ko, S L; Ostenson, J E; Lapertot, G; Cunningham, C E; Petrovic, C

    2001-03-12

    MgB2 becomes superconducting just below 40 K. Whereas porous polycrystalline samples of MgB2 can be synthesized from boron powders, in this Letter we demonstrate that dense wires of MgB2 can be prepared by exposing boron filaments to Mg vapor. The resulting wires have a diameter of 160 microm, are better than 80% dense, and manifest the full chi = -1/4pi shielding in the superconducting state. Temperature-dependent resistivity measurements indicate that MgB2 is a highly conducting metal in the normal state with rho(40 K) = 0.38 microOmega cm. By using this value, an electronic mean-free path, l approximately 600 A can be estimated, indicating that MgB2 wires are well within the clean limit. Tc, Hc2(T), and Jc data indicate that MgB2 manifests comparable or better superconducting properties in dense wire form than it manifests as a sintered pellet.

  6. Hydrogen radical processing -- In-situ semiconductor surface cleaning for epitaxial regrowth

    SciTech Connect

    Kuenzel, H.; Hase, A.; Griebenow, U.

    1996-12-31

    The achievement of high-quality interfaces for improved semiconductor device structures necessitates in-situ surface cleaning between different material deposition processes. In this contribution in-situ hydrogen radical exposure is presented as an advanced technique to obtain semiconductor surfaces adequate for MBE regrowth. Exposure of In-P-based materials to a thermal hydrogen radical beam at relatively low temperatures removes the native oxide layer from GaInAsP as well as AlGaInAs. In addition, accumulation of carbon, being the most prominent contaminant due to the exposure to air or intermediate ex-situ processing steps, is efficiently reduced. There is no indication of the occurrence of degradation of the treated material due to the hydrogen radical process which makes it especially suited for the fabrication of complex device structures.

  7. Biodegradation Rates Assessment For An In Situ Bioremediation Process

    NASA Astrophysics Data System (ADS)

    Troquet, J.; Poutier, F.

    Bioremediation methods seem a promising way of dealing with soil and subsoil con- tamination by organic substances. The biodegradation process is supported by micro- organisms which use the organic carbon from the pollutants as energy source and cells building blocks. However, bioremediation is not yet universally understood and its success is still an intensively debated issue because all soils and groundwater are not able to sustain biological growth and, then, cannot be successfully bioremediated. The outcome of each degradation process depends on several factors, which, such as oxygen transfer and pollutant bio-availability, can be controlled and are therefore key variables of such bioremediation processes. Then, it is essential to carry out a fea- sibility study based on pilot-testing before starting a remediation project in order to determine the best formulation of nutrients and bacteria to use for the specific condi- tions encountered. The scope of this work is to study the main parameters of the process and its physi- cal limiting steps in order to determine the biodegradation rates in a specific case of contamination. Several ground samples from an actual petroleum hydrocarbon con- taminated site have been laboratory tested. Five fixed bed column reactors, enabling the study of the influence of the different op- erating variables on the biodegradation kinetics, are used. The stoichiometric equation for bacteria growth and pollutant degradation has been established, allowing the de- termination of mass balances. Biodegradation monitoring is achieved by continuously measuring the emissions of carbon dioxide production and intermittently by analysing residual hydrocarbons. Results lead to the knowledge of biodegradation rates which allow to determine the treatment duration and cost.

  8. Noninvasive sensors for in-situ process monitoring and control in advanced microelectronics manufacturing

    NASA Astrophysics Data System (ADS)

    Moslehi, Mehrdad M.

    1991-04-01

    The combination of noninvasive in-situ monitoring sensors single-wafer processing modules vacuum-integrated cluster tools and computer-integrated manufacturing (CIM) can provide a suitable fabrication environment for flexible and high-yield advanced semiconductor device manufacturing. The use of in-situ sensors for monitoring of equipment process and wafer parameters results in increased equipment/process up-time reduced process and device parameter spread improved cluster tool reliability and functionality and reduced overall device manufacturing cycle time. This paper will present an overview of the main features and impact of noninvasive in-situ monitoring sensors for semiconductor device manufacturing applications. Specific examples will be presented for the use of critical sensors in conjunction with cluster tools for advanced CMOS device processing. A noninvasive temperature sensor will be presented which can monitor true wafer temperature via infrared (5. 35 jtm) pyrometery and laser-assisted real-time spectral wafer emissivity measurements. This sensor design eliminates any. temperature measurement errors caused by the heating lamp radiation and wafer emissivity variations. 1. SENSORS: MOTIVATIONS AND IMPACT Semiconductor chip manufacturing factories usually employ well-established statistical process control (SPC) techniques to minimize the process parameter deviations and to increase the device fabrication yield. The conventional fabrication environments rely on controlling a limited set of critical equipment and process parameters (e. g. process pressure gas flow rates substrate temperature RF power etc. ) however most of the significant wafer process and equipment parameters of interest are not monitored in real

  9. Experimental Investigation and High Resolution Simulator of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2006-07-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this current and eleventh report, we report on the development of a virtual kinetic cell (VKC) that aids the study of the interaction between kinetics and phase behavior. The VKC also provides an excellent tool for developing and testing specialized solvers for the stiff kinetics encountered in ISC processes.

  10. Experimental Investigation and High Resolution Simulation of In-Situ Combustion Processes

    SciTech Connect

    Margot Gerritsen; Tony Kovscek

    2008-04-30

    This final technical report describes work performed for the project 'Experimental Investigation and High Resolution Numerical Simulator of In-Situ Combustion Processes', DE-FC26-03NT15405. In summary, this work improved our understanding of in-situ combustion (ISC) process physics and oil recovery. This understanding was translated into improved conceptual models and a suite of software algorithms that extended predictive capabilities. We pursued experimental, theoretical, and numerical tasks during the performance period. The specific project objectives were (i) identification, experimentally, of chemical additives/injectants that improve combustion performance and delineation of the physics of improved performance, (ii) establishment of a benchmark one-dimensional, experimental data set for verification of in-situ combustion dynamics computed by simulators, (iii) develop improved numerical methods that can be used to describe in-situ combustion more accurately, and (iv) to lay the underpinnings of a highly efficient, 3D, in-situ combustion simulator using adaptive mesh refinement techniques and parallelization. We believe that project goals were met and exceeded as discussed.

  11. In-situ characterization of colloidal soft solution processes.

    SciTech Connect

    Tallant, David Robert; Rodriguez, Mark Andrew; Bell, Nelson Simmons

    2003-11-01

    The purpose of this program was to investigate methods to characterize the colloidal stability of nanoparticles during the synthesis reaction, and to characterize their organization related to interparticle forces. Studies were attempted using Raman spectroscopy and ultrasonic attenuation to observe the nucleation and growth process with characterization of stability parameters such as the zeta potential. The application of the techniques available showed that the instrumentation requires high sensitivity to the concentration of the system. Optical routes can be complicated by the scattering effects of colloidal suspensions, but dilution can cause a lowering of signal that prevents collection of data. Acoustic methods require a significant particle concentration, preventing the observation of nucleation events. Studies on the dispersion of nanoparticles show that electrostatic routes are unsuccessful with molecular surfactants at high particle concentration due to electrostatic interaction collapse by counterions. The study of molecular surfactants show that steric lengths on the order of 2 nm are successful for dispersion of nanoparticle systems at high particle concentration, similar to dispersion with commercial polyelectrolyte surfactants.

  12. In-situ steam drive oil recovery process

    SciTech Connect

    Vanmeurs, P.; Waxman, M.H.; Vinegar, H.J.

    1987-02-03

    A process is described for heating a subterranean oil and water-containing reservoir formation, comprising: completing at least one each of heat-injecting and fluid-producing wells into a treatment interval of the formation which is at least about 100 feet thick, contains both oil and water, and is both undesirably impermeable and non-productive in response to injections of oil recovery fluids; arranging the wells to have boreholes which, substantially throughout the treatment interval, are substantially parallel and are separated by substantially equal distances of at least about 20 feet; in each heat-injecting well, substantially throughout the treatment interval, sealing the face of the reservoir formation with a solid material which is relatively heat-conductive and substantially fluid impermeable; in each fluid-producing well, substantially throughout the treatment interval, establishing fluid communication between the wellbore and the reservoir formation and arranging the well for producing fluid from the reservoir formation; and heating the interior of each heat-injecting well, at least substantially throughout the treatment interval, at a rate or rates capable of (a) increasing the temperature within the borehole interior to at least about 600/sup 0/C. and (b) maintaining a borehole interior temperature of at least about 600/sup 0/C. without causing it to become high enough to thermally damage equipment within the borehole while heat is being transmitted away from the borehole at a rate not significantly faster than that permitted by the thermal conductivity of the reservoir formation.

  13. Using A Wireless In Situ Probe To Monitor Subglacial Processes

    NASA Astrophysics Data System (ADS)

    Hart, J. K.; Martinez, K.

    2010-12-01

    The Glacsweb system (http://envisense.org/glacsweb/) has been installed in two glaciers; Briksdalsbreen, Norway and Skalafellsjökull, Iceland. These are valley glaciers which show evidence of subglacial deformation in the foreland, with flutes and push moraines. Briksdalsbreen was calving into a glacial lake. This advanced 390m between 1987-1996 and then retreated over 460m between 1996 and 2008. Skalafellsjökull is landbased with a similar (but smaller scale) pattern of recent glacier marginal. Micro-sensors housed within the Glacsweb probes (0.16m long) measured water pressure, probe deformation, resistance, tilt and probe temperature within the ice or till. These data were recorded at a number of times during the day, and transmitted to a base station located on the glacier surface. Probe and meteorological data were sent once a day to a local mains powered computer, where it was forwarded to a web server in the UK. At Briksdalsbreen this operated from August 2004 to August 2006, and at Skalafellsjökull, it operated from August 2008 onwards (with periods when the system was disconnected). We compare the subglacial processes recorded throughout the year at the two sites. In particular, changes in water pressure, case stress, till water contents and till temperatures.

  14. Flux pinning and vortex dynamics in MgB2 doped with TiO2 and SiC inclusions

    NASA Astrophysics Data System (ADS)

    Prokhorov, V. G.; Kaminsky, G. G.; Svetchnikov, V. L.; Park, J. S.; Eom, T. W.; Lee, Y. P.; Kang, J.-H.; Khokhlov, V. A.; Mikheenko, P.

    2009-06-01

    The mixed-state superconducting properties of bulk MgB2+2at.%TiO2 and +8at.%SiC, prepared by in situ solid state reaction, are investigated. Analysis of the mixed-state parameters, such as the upper critical field, the coherence length, and the Ginzburg-Landau parameter, proves that MgB2+2at.%TiO2 is a high-κ type-II superconductor in the dirty limit, while MgB2+8at.%SiC corresponds to that in the moderately clean limit. It is shown that the grain-boundary pinning realized in fine-grained doped MgB2 polycrystals is of the anisotropic rather than the electron-scattering type. The field-cooled temperature dependences of the magnetic moment reveal a transition of the samples to the paramagnetic state at certain applied magnetic fields, which is treated as manifestation of the paramagnetic Meissner effect. The experimental results are discussed on the base of modern theoretical approaches.

  15. Strong enhancement of high-field critical current properties and irreversibility field of MgB2 superconducting wires by coronene active carbon source addition via the new B powder carbon-coating method

    NASA Astrophysics Data System (ADS)

    Ye, Shu Jun; Matsumoto, Akiyoshi; Chao Zhang, Yun; Kumakura, Hiroaki

    2014-08-01

    We report an effective carbon-containing additive, coronene (C24H12), for MgB2 superconducting wires. We used B powder coated with C24H12 to fabricate MgB2 wires using the powder-in-tube (PIT) and internal Mg diffusion (IMD) processes. The in-field critical current properties are strongly enhanced for both PIT- and IMD-processed MgB2 wires. For PIT MgB2 wires, a critical current density (Jc) value of 1.8 × 104 A cm-2 is obtained at 4.2 K and 10 T. For IMD MgB2 wires, we obtained a Jc of 1.07 × 105 A cm-2 and an engineering Jc (Je) of 1.12 × 104 A cm-2 at 4.2 K and 10 T. These Jc and Je values are similar to the highest values reported for MgB2 wires thus far. Furthermore, the irreversibility field, Birr, determined with a current density criterion of 100 A cm-2, is strongly enhanced to 25 T at 4.2 K, which is also the highest value reported for MgB2 superconducting wires thus far. Coronene is an active carbon source for MgB2 superconducting wires because (1) coronene has a high carbon content (96 wt%) with a small amount of hydrogen (impurity), (2) the decomposition temperature for coronene is near the reaction temperature between Mg and B, and (3) uniform dispersion of coronene on the B surface can be obtained due to the melting point of coronene being lower than the decomposition temperature. Carbon substitution for B caused by the coronene active carbon source is mainly responsible for the high field critical current properties and the high Birr obtained in this work.

  16. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    DOE PAGES

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; et al

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipactingmore » issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.« less

  17. In-situ plasma processing to increase the accelerating gradients of superconducting radio-frequency cavities

    NASA Astrophysics Data System (ADS)

    Doleans, M.; Tyagi, P. V.; Afanador, R.; McMahan, C. J.; Ball, J. A.; Barnhart, D. L.; Blokland, W.; Crofford, M. T.; Degraff, B. D.; Gold, S. W.; Hannah, B. S.; Howell, M. P.; Kim, S.-H.; Lee, S.-W.; Mammosser, J.; Neustadt, T. S.; Saunders, J. W.; Stewart, S.; Strong, W. H.; Vandygriff, D. J.; Vandygriff, D. M.

    2016-03-01

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. In this article, the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus are discussed.

  18. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    SciTech Connect

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; Neustadt, Thomas S.; Saunders, Jeffrey W.; Tyagi, Puneet V.; Vandygriff, Daniel J.; Vandygriff, David M.; Ball, Jeffrey Allen; Blokland, Willem; Crofford, Mark T.; Lee, Sung-Woo; Stewart, Stephen; Strong, William Herb

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.

  19. DEMONSTRATION BULLETIN: IN SITU STEAM ENHANCED RECOVERY PROCESS - HUGHES ENVIRONMENTAL SYSTEMS, INC.

    EPA Science Inventory

    The Steam Enhanced Recovery Process (SERP) is designed to remove volatile compounds such as halogenated solvents and petroleum hydrocarbons, and semi-volatile compounds from contaminated soils in situ. The vapor pressures of most contaminants will increase by the addition of ste...

  20. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 3 2012-07-01 2012-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  1. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 3 2011-07-01 2011-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  2. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 3 2014-07-01 2014-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  3. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  4. 30 CFR 903.828 - Special performance standards-In situ processing.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 3 2013-07-01 2013-07-01 false Special performance standards-In situ processing. 903.828 Section 903.828 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE...

  5. In situ heat treatment process utilizing a closed loop heating system

    SciTech Connect

    Vinegar, Harold J.; Nguyen, Scott Vinh

    2010-12-07

    Systems and methods for an in situ heat treatment process that utilizes a circulation system to heat one or more treatment areas are described herein. The circulation system may use a heated liquid heat transfer fluid that passes through piping in the formation to transfer heat to the formation. In some embodiments, the piping may be positioned in at least two of the wellbores.

  6. EPA SITE DEMONSTRATION OF THE TERRA VAC IN SITU VACUUM EXTRACTION PROCESS IN GROVELAND, MASSACHUSETTS

    EPA Science Inventory

    This paper presents an EPA evaluation of the patented Terra Vac, Inc.'s in situ vacuum extraction process that was field-demonstrated on a trichloroethylene (TCE) contaminated soil in Groveland, MA, under the EPA Superfund Innovative Technology Evaluation (SITE) program. he Terra...

  7. DEMONSTRATION BULLETIN: COLD TOP EX-SITU VITRIFICATION PROCESS - GEOTECH DEVELOPMENT CORPORATION

    EPA Science Inventory

    The Cold Top Vitrification process, developed by Geotech Development Corporation, is an ex-situ, submerged-electrode, resistance-melting technology. The technology is designed to transform heavy metal contaminated soil into a glassy, amorphous, non-leachable mass composed of inte...

  8. XPERT DESIGN AND DIAGNOSTICS' (XDD) IN-SITU CHEMICAL OXIDATION PROCESS USING POTASSIUM PERMANGANATE (KMNO4)

    EPA Science Inventory

    Xpert Design and Diagnostic's (XDD)potassium permanganate in situ chemical oxidation (ISCO) process was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program at the former MEC Building site located in Hudson, New Hampshire. At this site, both soil and ...

  9. Investigation of the Geokinetics horizontal in situ oil-shale-retorting process. Fourth annual report, 1980

    SciTech Connect

    Hutchinson, D.L.

    1981-03-01

    The Geokinetics in situ shale oil project is a cooperative venture between Geokinetics Inc. and the US Department of Energy. The objective is to develop a true in situ process for recovering shale oil using a fire front moving in a horizontal direction. The project is being conducted at a field site, Kamp Kerogen, located 70 miles south of Vernal, Utah. This Fourth Annual Report covers work completed during the calendar year 1980. During 1980 one full-size retort was blasted. Two retorts, blasted the previous year, were burned. A total of 4891 barrels of oil was produced during the year.

  10. Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels: Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors

    SciTech Connect

    Dutta, Abhijit; Sahir, A. H.; Tan, Eric; Humbird, David; Snowden-Swan, Lesley J.; Meyer, Pimphan A.; Ross, Jeff; Sexton, Danielle; Yap, Raymond; Lukas, John

    2015-03-01

    This report was developed as part of the U.S. Department of Energy’s Bioenergy Technologies Office’s efforts to enable the development of technologies for the production of infrastructure-compatible, cost-competitive liquid hydrocarbon fuels from biomass. Specifically, this report details two conceptual designs based on projected product yields and quality improvements via catalyst development and process integration. It is expected that these research improvements will be made within the 2022 timeframe. The two conversion pathways detailed are (1) in situ and (2) ex situ upgrading of vapors produced from the fast pyrolysis of biomass. While the base case conceptual designs and underlying assumptions outline performance metrics for feasibility, it should be noted that these are only two of many other possibilities in this area of research. Other promising process design options emerging from the research will be considered for future techno-economic analysis. Both the in situ and ex situ conceptual designs, using the underlying assumptions, project MFSPs of approximately $3.5/gallon gasoline equivalent (GGE). The performance assumptions for the ex situ process were more aggressive with higher distillate (diesel-range) products. This was based on an assumption that more favorable reaction chemistry (such as coupling) can be made possible in a separate reactor where, unlike in an in situ upgrading reactor, one does not have to deal with catalyst mixing with biomass char and ash, which pose challenges to catalyst performance and maintenance. Natural gas was used for hydrogen production, but only when off gases from the process was not sufficient to meet the needs; natural gas consumption is insignificant in both the in situ and ex situ base cases. Heat produced from the burning of char, coke, and off-gases allows for the production of surplus electricity which is sold to the grid allowing a reduction of approximately 5¢/GGE in the MFSP.

  11. Substitution of Mn for Mg in MgB_2*

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Michael D.; Johnston, David C.; Miller, Lance L.; Hill, Julienne M.

    2002-03-01

    The study of solid solutions in which the Mg in MgB2 is partially replaced by magnetic 3d or 4f atoms can potentially reveal important information on the superconducting state of MgB_2. As an end-member of the hypothetical Mg_1-xMn_xB2 system, MnB2 is isostructural with MgB2 and is an antiferromagnet below TN = 760 K which becomes canted at 157 K. A previous study by Moritomo et al.[1] examined the structure and properties of multi-phase samples with 0.01<= x<= 0.15. We attempted to obtain single-phase samples with x<= 0.25 by reacting the constituent elements in sealed Ta tubes and/or using prereacted MnBx synthesized using an arc furnace. The results of x-ray diffraction and magnetization measurements on those samples will be presented. * Supported by the USDOE under contract no. W-7405-Eng-82. [1] "Mn-substitution effects on MgB2 superconductor", Y.Moritomo et al. J. Phys. Soc. Japan b70, 1889 (2001).; “Effects of transition metal doping in MgB2 superconductor", Y. Moritomo at al. arXiv:cond-mat/0104568.

  12. Analytical Model for the Diffusion Process in a In-Situ Combustion Tube

    NASA Astrophysics Data System (ADS)

    Gutierrez, Patricia; Reyes, Adrian

    2015-03-01

    The in-situ combustion process (ISC) is basically an air or oxygen enriched gas injection oil recovery process, inside an extraction well. In contrast to a conventional gas injection process, an ISC process consists in using heat to create a combustion front that raises the fuel temperature, decreasing its viscosity, making extraction easier. The oil is taken toward the productor by means of a vigorous gas thrust as well as a water thrust. To improve and enhance this technique in the field wells, it has been widely perform experimental laboratory tests, in which an in-situ combustion tube is designed to simulate the extraction process. In the present work we propose to solve analytically the problem, with a parabolic partial differential equation associated to the convection-diffusion phenomenon, equation which describes the in-situ combustion process. The whole mathematical problem is established by completing this equation with the correspong boundary and initial conditions, the thickness of the combustion zone, flow velocity, and more parameters. The theoretically obtained results are compared with those reported in literature. We further, fit the parameter of our model to the mentioned data taken from the literature.

  13. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2005-04-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this sixth quarter of our DoE funded research, we continued the development of our new simulation tool which is based on an efficient Cartesian Adaptive Mesh Refinement technique. This methodology allows much higher grid densities to be used near typical fronts than current simulators. We improved the upscaling strategy on these grids, and derived an effective way to generate upscaled permeabilities that preserve local fluxes. We have started more in-depth research into splitting methods for stiff PDEs such as those found in in-situ combustion simulation. We will report on these new developments extensively in the next quarterly report. This quarterly report, we focus on experimental work. On the experimental side, we have fleshed out a mechanism of improved in-situ combustion with aqueous metallic salts using scanning electron microscopy (SEM) and the transport phenomenon of such additives through porous media. Based on the observations from SEM analysis, we propose cation exchange of metallic salts with clay as a mechanism to create activated sites that enhance combustion reactions between oil and oxygen. Moreover, the empirical ranking of the success of metallic ions as catalytic additives for in-situ combustion is interpreted as originating from three factors: cation replacing power, distribution of metallic additive adsorption sites, and cation catalytic power for oxidation and cracking of hydrocarbon.

  14. Monitoring the evolution of crystallization processes by in-situ solid-state NMR spectroscopy.

    PubMed

    Harris, Kenneth D M; Hughes, Colan E; Williams, P Andrew

    2015-02-01

    Crystallization processes play a crucial role in many aspects of biological and physical sciences. Progress in deepening our fundamental understanding of such processes relies, to a large extent, on the development and application of new experimental strategies that allow direct in-situ monitoring of the process. In this paper, we give an overview of an in-situ solid-state NMR strategy that we have developed in recent years for monitoring the time-evolution of different polymorphic forms (or other solid forms) that arise as the function of time during crystallization from solution. The background to the strategy is described and several examples of the application of the technique are highlighted, focusing on both the evolution of different polymorphs during crystallization and the discovery of new polymorphs.

  15. In situ analysis of adsorption process from residual gases during thin film deposition

    NASA Astrophysics Data System (ADS)

    Giedraitis, A.; Tamulevicius, S.; Slapikas, K.; Gudaitis, R.; Juraitis, A.

    2008-03-01

    In this work we present the developed experimental technique as well as results of optical control of adsorption processes during thin film deposition. Different metallic films: (silver) as a model material and barium getter films were studied. Thermal evaporation method has been used to deposit thin metallic films and films of barium getter on glass substrates. Kinetics of the optical absorbance of the growing film was registered in situ measuring transmission of the film-substrate structure. These measurements were done in parallel to the ex-situ absorption (UV-VIS) and reflection spectra as well as XRD analysis. Such complex measurements enabled us to follow adsorption process from the residual gases during thermal evaporation as well to control adsorption process after the evaporation.

  16. On-line in-situ control of the resin transfer molding process

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D.; Eichinger, D.; Williamson, A.; Levy, D.; Reyzer, M.

    1990-01-01

    Resin transfer molding of three-dimensionally stitched fabrics promises to be a cost effective process for obtaining composite parts of exceptional strength. The technique eliminates many problems involving prepreg preparation, storage and layup. It replaces, on the other hand, the single step cure process with a two-stage impregnation and cure process. Of particular importance therefore is selecting and controlling the viscosity during impregnation and cure. The use of in-situ frequency-dependent electromagnetic sensors and the Loos-Springer model for selecting and controllng the processing properties of the resin transfer molding resin during impregnation and cure are discussed.

  17. EBSD analysis of MgB2 bulk superconductors

    NASA Astrophysics Data System (ADS)

    Koblischka-Veneva, A.; Koblischka, M. R.; Schmauch, J.; Inoue, K.; Muralidhar, M.; Berger, K.; Noudem, J.

    2016-04-01

    The grain orientation, the texture and the grain boundary misorientations are important parameters for the understanding of the magnetic properties of the bulk MgB2 samples intended for super-magnet applications. Such data can be provided by electron backscatter diffraction (EBSD) analysis. However, as the grain size (GS) of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique working in reflection operates properly only on highly dense samples. In order to achieve a reasonably good Kikuchi pattern quality on all samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to several bulk MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analyzed within the SEM, operating with a specific sample holder. We present several EBSD mappings of samples prepared with different techniques and at various reaction temperatures.

  18. In Situ Chemical Modification of Schottky Barrier in Solution-Processed Zinc Tin Oxide Diode.

    PubMed

    Son, Youngbae; Li, Jiabo; Peterson, Rebecca L

    2016-09-14

    Here we present a novel in situ chemical modification process to form vertical Schottky diodes using palladium (Pd) rectifying bottom contacts, amorphous zinc tin oxide (Zn-Sn-O) semiconductor made via acetate-based solution process, and molybdenum top ohmic contacts. Using X-ray photoelectron spectroscopy depth profiling, we show that oxygen plasma treatment of Pd creates a PdOx interface layer, which is then reduced back to metallic Pd by in situ reactions during Zn-Sn-O film annealing. The plasma treatment ensures an oxygen-rich environment in the semiconductor near the Schottky barrier, reducing the level of oxygen-deficiency-related defects and improving the rectifying contact. Using this process, we achieve diodes with high forward current density exceeding 10(3)A cm(-2) at 1 V, rectification ratios of >10(2), and ideality factors of around 1.9. The measured diode current-voltage characteristics are compared to numerical simulations of thermionic field emission with sub-bandgap states in the semiconductor, which we attribute to spatial variations in metal stoichiometry of amorphous Zn-Sn-O. To the best of our knowledge, this is the first demonstration of vertical Schottky diodes using solution-processed amorphous metal oxide semiconductor. Furthermore, the in situ chemical modification method developed here can be adapted to tune interface properties in many other oxide devices. PMID:27559750

  19. Superconductivity of Metallic Boron in MgB2

    NASA Astrophysics Data System (ADS)

    Kortus, J.; Mazin, I. I.; Belashchenko, K. D.; Antropov, V. P.; Boyer, L. L.

    2001-05-01

    Boron in MgB2 forms stacks of honeycomb layers with magnesium as a space filler. Band structure calculations indicate that Mg is substantially ionized, and the bands at the Fermi level derive mainly from B orbitals. Strong bonding with an ionic component and considerable metallic density of states yield a sizable electron-phonon coupling. Together with high phonon frequencies, which we estimate via zone-center frozen phonon calculations to be between 300 and 700 cm-1, this produces a high critical temperature, consistent with recent experiments. Thus MgB2 can be viewed as an analog of the long sought, but still hypothetical, superconducting metallic hydrogen.

  20. Superconductivity of metallic boron in MgB2.

    PubMed

    Kortus, J; Mazin, I I; Belashchenko, K D; Antropov, V P; Boyer, L L

    2001-05-14

    Boron in MgB2 forms stacks of honeycomb layers with magnesium as a space filler. Band structure calculations indicate that Mg is substantially ionized, and the bands at the Fermi level derive mainly from B orbitals. Strong bonding with an ionic component and considerable metallic density of states yield a sizable electron-phonon coupling. Together with high phonon frequencies, which we estimate via zone-center frozen phonon calculations to be between 300 and 700 cm(-1), this produces a high critical temperature, consistent with recent experiments. Thus MgB2 can be viewed as an analog of the long sought, but still hypothetical, superconducting metallic hydrogen.

  1. Superconducting properties of MgB2 from first principles.

    PubMed

    Floris, A; Profeta, G; Lathiotakis, N N; Lüders, M; Marques, M A L; Franchini, C; Gross, E K U; Continenza, A; Massidda, S

    2005-01-28

    Solid MgB(2) has rather interesting and technologically important properties, such as a very high superconducting transition temperature. Focusing on this compound, we report the first nontrivial application of a novel density-functional-type theory for superconductors, recently proposed by the authors. Without invoking any adjustable parameters, we obtain the transition temperature, the gaps, and the specific heat of MgB(2) in very good agreement with experiment. Moreover, our calculations show how the Coulomb interaction acts differently on sigma and pi states, thereby stabilizing the observed superconducting phase.

  2. Boron isotope effect in superconducting MgB2.

    PubMed

    Bud'ko, S L; Lapertot, G; Petrovic, C; Cunningham, C E; Anderson, N; Canfield, P C

    2001-02-26

    We report the preparation method of and boron isotope effect for MgB2, a new binary intermetallic superconductor with a remarkably high superconducting transition temperature T(c)(10B) = 40.2 K. Measurements of both temperature dependent magnetization and specific heat reveal a 1.0 K shift in T(c) between Mg11B2 and Mg10B2. Whereas such a high transition temperature might imply exotic coupling mechanisms, the boron isotope effect in MgB2 is consistent with the material being a phonon-mediated BCS superconductor.

  3. In-situ real time monitoring of the polymerization in gel-cast ceramic processes

    SciTech Connect

    Ahuja, S.; Dieckman, S.L.; Bostrom, G.A.; Waterfield, L.G.; Raptis, A.C.; Omatete, O.O.

    1996-08-01

    Gelcasting requires making a mixture of a slurry of ceramic powder in a solution of organic monomers and casting it in a mold. Gelcasting is different from injection molding in that it separates mold filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging were used for in-situ monitoring of the gelation process and gelcasting of alumina. {sup 1}H NMR spectra and images are obtained during polymerization of a mixture of soluble reactive acrylamide monomers. Polymerization was initiated by adding an initiator and an accelerator to form long- chain, crosslinked polymers. Multidimensional NMR imaging was used for in-situ monitoring of the process and for verification of homogeneous polymerization. Comparison of the modeled intensities with acquired images shows a direction extraction of T{sub 1} data from the images.

  4. Magnetoelectric composite ceramics of nickel ferrite and lead zirconate titanate via in situ processing

    NASA Astrophysics Data System (ADS)

    Wu, Dandan; Gong, Weihua; Deng, Haijin; Li, Ming

    2007-08-01

    Magnetoelectric (ME) composite ceramics of NiFe2O4 (NFO) and lead zirconate titanate (PZT) were synthesized by a simple in situ processing based on a sol-gel method followed by a conventional sintering. X-ray diffraction patterns and scanning electron microscopy images revealed that this processing can produce two pure phases simultaneously. The in situ grown magnetic NiFe2O4 grains were well dispersed in the PZT matrix. The results demonstrated an attractive ME response of about 28.5 V cm-1 Oe-1 in the 0.35 NiFe2O4/0.65PZT at a resonance frequency of around 287 kHz.

  5. Process modeling of in situ-adsorption of a bacterial lipase.

    PubMed

    Millitzer, Marcus; Wenzig, Edda; Peukert, Wolfgang

    2005-12-20

    In situ adsorption, known as an in situ-roduct removal (ISPR) technique for low molecular mass bioproducts, was in this study applied to a bacterial exoenzyme proving that this method is also suitable for the separation of macromolecules like proteins. For this, adsorbent particles were added to growing cultures of Staphylococcus carnosus rec., therefore both production and adsorption occurred simultaneously in shaking flasks, stirred tank, or airlift bioreactor as the chosen types of fermenters. The exoenzyme lipase adsorbed rapidly and, after separating cells and adsorbents, desorbed in a packed bed column. Up to 85% of the produced lipase were recovered, fractions of these had been concentrated up to the factor 20 and purified up to a factor of 40 by the procedure. By using the airlift bioreactor an enhancement of biomass production was observed, but the necessity of the addition of an anti-foam reagent resulted in higher product losses in adsorption as well as in desorption. Production and adsorption kinetics have been modeled and applied to in situ-adsorption. The model was used to perform a parameter study in which the influence of biological and physical parameters as well as process parameters on discontinuous and continuous in situ-adsorption was investigated. PMID:16267849

  6. A quantitative framework for understanding complex interactions between competing interfacial processes and in situ biodegradation.

    PubMed

    Johnson, Mark A; Song, Xin; Seagren, Eric A

    2013-03-01

    In situ bioremediation of contaminated groundwater is made technologically challenging by the physically, chemically, and biologically heterogeneous subsurface environment. Subsurface heterogeneities are important because of influences on interfacial mass transfer processes that impact the availability of substrates to microorganisms. The goal of this study was to perform a "proof-of-concept" evaluation of the utility of a quantitative framework based on a set of dimensionless coefficients for evaluating the effects of competing physicochemical interfacial and biokinetic processes at the field scale. First, three numerical modeling experiments were completed, demonstrating how the framework can be used to identify the rate-limiting process for the overall bioremediation rate, and to predict what engineered enhancements will alleviate the rate-limiting process. Baseline conditions for each scenario were established to examine intrinsic biodegradation with a given rate-limiting process (either dispersion, biokinetics, or sorption). Then different engineering treatments were examined. In each case, the treatment predicted to be appropriate for addressing the overall rate-limiting process based on the quantitative framework alleviated the limitation more successfully, and enhanced the in situ biodegradation rate more than the alternative enhancements. Second, the quantitative framework was applied to a series of large-scale laboratory and field-scale experiments, using reported parameter estimates to calculate the relevant dimensionless coefficients and predict the rate-limiting process(es). Observations from the studies were then used to evaluate those predictions.

  7. Ultrafast laser processing of transparent materials supported by in-situ diagnostics

    NASA Astrophysics Data System (ADS)

    Kumkar, M.; Kaiser, M.; Kleiner, J.; Grossmann, D.; Flamm, D.; Bergner, K.; Nolte, S.

    2016-03-01

    For the development of industrial NIR ultrafast laser processing of transparent materials, the absorption inside the bulk material has to be controlled. Applications we aim for are front and rear side ablation, drilling and inscription of modifications for cleaving and selective laser etching of glass and sapphire in sheet geometry. We applied pump probe technology and in situ stress birefringence microscopy for fundamental studies on the influence of energy and duration (100 fs - 20 ps), temporal and spatial spacing, focusing and beam shaping of the laser pulses. Applying pump probe technique we are able to visualize differences of spatio-temporal build up of absorption, self focusing, shock wave generation for standard, multispot and beam shaped focusing. Incubation effects and disturbance of beam propagation due to modifications or ablation can be observed. In-situ imaging of stress birefringence gained insight in transient build up of stress with and without translation. The results achieved so far, demonstrate that transient stress has to be taken into account in scaling the laser machining throughput of brittle materials. Furthermore it points out that transient stress birefringence is a good indicator for accumulation effects, supporting tailored processing strategies. Cutting results achieved for selective laser etching by single pass laser modification exemplifies the benefits of process development supported by in situ diagnostics.

  8. Combining In-situ and In-transit Processing to Enable Extreme-Sscale Scientific Analysis

    SciTech Connect

    Bennett, Janine C.; Abbasi, Hasan; Bremer, Peer-Timo; Grout, Ray; Gyulassy, Attila; Jin, Tong; Klasky, Scott A; Kolla, Hemanth; Parashar, Manish; Pascucci, Valerio; Pebay, Philippe; Thompson, David; Yu, Hongfeng; Zhang, Fan; Chen, Jacqueline H

    2012-01-01

    With the onset of extreme-scale computing, I/O constraints make it increasingly difficult for scientists to save a sufficient amount of raw simulation data to persistent storage. One potential solution is to change the data analysis pipeline from a post-process centric to a concurrent approach based on either in-situ or in-transit processing. In this context computations are considered in-situ if they utilize the primary compute resources, while in-transit processing refers to offloading computations to a set of secondary resources using asynchronous data transfers. In this paper we explore the design and implementation of three common analysis techniques typically performed on large-scale scientific simulations: topological analysis, descriptive statistics, and visualization. We summarize algorithmic developments, describe a resource scheduling system to coordinate the execution of various analysis workflows, and discuss our implementation using the DataSpaces and ADIOS frameworks that support efficient data movement between in-situ and in-transit computations. We demonstrate the efficiency of our lightweight, flexible framework by deploying it on the Jaguar XK6 to analyze data generated by S3D, a massively parallel turbulent combustion code. Our framework allows scientists dealing with the data deluge at extreme scale to perform analyses at increased temporal resolutions, mitigate I/O costs, and significantly improve the time to insight.

  9. Description and capabilities of the large-scale in situ vitrification process

    SciTech Connect

    Buelt, J.L.; Carter, J.G.

    1986-01-01

    An emerging thermal treatment process known as in situ vitrification is being developed to immobilize selected portions of radioactively contaminated soils. The process is a permanent remedial action that destroys solid and liquid organic contaminants and incorporates radionuclides and heavy metals into a glass and crystalline form. The process's flexibility in design and broad capabilities make it potentially adaptable to mixed and chemical wastes, as well. The process consists of an electrical power system for vitrifying contaminated soil, a hood to contain gaseous effluents, an off-gas treatment system, an off-gas cooling system, and a process control station. The process is mounted in three transportable trailers that can be easily moved from site to site. The process is capable of treating contaminated soils at least 13 m deep. The system components are designed to accommodate waste inclusions in the soil such as metals, combustibles, and large voids. Selectively applied to the more troublesome radioactively contaminated soils, in situ vitrification provides a potentially useful and permanent tool for remedial action.

  10. Phase 1 Final Technical Report - MgB2 Synthesis for High Field Performance

    SciTech Connect

    Mohit Bhatia; Peter McIntyre

    2009-11-02

    boron results in the formation of parasitic phases such as MgB4, MgB7, etc. Such parasitic phases are a primary element of the connectivity problem, in which even though a sample powder may contain grains of high-quality MgB2, adjacent grains are surrounded by intergrowths of parasitic phases so that current trans-port is badly degraded. The best results to date have been obtained using boron powder produced long ago for a rocket propellant development project. The synthesis process was complex and is now largely lost, and the manufacturing equipment has long since been scrapped. The last batch of the powder has been used during recent years to support MgB2 R&D at several labs, but supplies are dwindling. ATC has identified a first application of its plasma torch to synthesize phase-pure amorphous boron flake using a rapid-quench splat technique. Inexpensive technical-grade boron would be purified of contaminants, then dispersed as an aerosol in inert gas and passed through the plasma torch to melt it into a spray. The spray would be splat-condensed on a rotating drum to form pure amorphous flake. The process would begin with technical-grade boron powder, having good stoichiometric purity, nanoscale particles, but significant contamination of MgO and crystalline boron. We used wet chemistry to remove B2O3 completely and reduced the MgO impurity, and analyzed the particle size distribution using a Coulter counter and the phase composition using X-ray diffrac-tion (XRD). The next step will be to build an rf plasma torch with a recirculating single-component aerosol feed and the cooled splat drum and collector, and undertake process devel-opment for amorphous boron powder. This revised goal has two benefits. First, it is an easier technology than our ultimate goal of a multi-component laminar flow torch. We have been counseled by those experienced in plasma torch technology that our ultimate goal will require a torch that should be feasible but has never been attempted. It

  11. Thermographic In-Situ Process Monitoring of the Electron Beam Melting Technology used in Additive Manufacturing

    SciTech Connect

    Dinwiddie, Ralph Barton; Dehoff, Ryan R; Lloyd, Peter D; Lowe, Larry E; Ulrich, Joseph B

    2013-01-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  12. In-situ guidance of individual neuronal processes by wet femtosecond-laser processing of self-assembled monolayers

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hideaki; Okano, Kazunori; Demura, Takanori; Hosokawa, Yoichiroh; Masuhara, Hiroshi; Tanii, Takashi; Nakamura, Shun

    2011-10-01

    In-situ guidance of neuronal processes (neurites) is demonstrated by applying wet femtosecond-laser processing to an organosilane self-assembled monolayer (SAM) template. By scanning focused laser beam between cell adhesion sites, on which primary neurons adhered and extended their neurites, we succeeded in guiding the neurites along the laser-scanning line. This guidance was accomplished by multiphoton laser ablation of cytophobic SAM layer and subsequent adsorption of cell adhesion molecule, laminin, onto the ablated region. This technique allows us to arbitrarily design neuronal networks in vitro.

  13. In-situ guidance of individual neuronal processes by wet femtosecond-laser processing of self-assembled monolayers

    PubMed Central

    Yamamoto, Hideaki; Okano, Kazunori; Demura, Takanori; Hosokawa, Yoichiroh; Masuhara, Hiroshi; Tanii, Takashi; Nakamura, Shun

    2011-01-01

    In-situ guidance of neuronal processes (neurites) is demonstrated by applying wet femtosecond-laser processing to an organosilane self-assembled monolayer (SAM) template. By scanning focused laser beam between cell adhesion sites, on which primary neurons adhered and extended their neurites, we succeeded in guiding the neurites along the laser-scanning line. This guidance was accomplished by multiphoton laser ablation of cytophobic SAM layer and subsequent adsorption of cell adhesion molecule, laminin, onto the ablated region. This technique allows us to arbitrarily design neuronal networks in vitro. PMID:27703280

  14. MgB2UltrathinFilms Fabricated by Hybrid Physical Chemical Vapor Deposition and Subsequent Ion Milling

    NASA Astrophysics Data System (ADS)

    Acharya, Narendra; Wolak, Matthaeus; Tan, Teng; Cunnane, Daniel; Karasik, Boris; Xi, Xiaoxing

    Hot electron bolometer (HEB) mixers are a great tool for measuring high-resolution spectroscopy at Terahertz frequencies. MgB2offers a higher critical temperature (39 K) compared to commonly used Nb and NbN and boasts a shorter intrinsic electron-phonon relaxation time, giving rise to a broader intermediate frequency (IF) bandwidth. We have fabricated high quality ultrathin MgB2films using hybrid physical-chemical vapor deposition (HPCVD) and employing ion milling to achieve thickness down to 2 nm. The thinnest achieved films show high Tc of 28 K with residual resistivity below 28 µ Ωcm and high critical current Jcof 1x106 A/cm2at 20 K. As a result of the employed low angle ion milling process, the films remain well connected even after being thinned down since the initial thick films offer a better connectivity than as-grown thin films. The established process offers a way to realize MgB2 based HEB mixers of extremely low thickness and therefore small local oscillator power requirements and increased IF bandwidth.

  15. A simple constrained uniaxial tensile apparatus for in situ investigation of film stretching processing

    NASA Astrophysics Data System (ADS)

    Meng, Lingpu; Li, Jing; Cui, Kunpeng; Chen, Xiaowei; Lin, Yuanfei; Xu, Jiali; Li, Liangbin

    2013-11-01

    A simple constrained uniaxial tensile apparatus was designed and constructed to obtain stress-strain curve during stretching and subsequent structural evolution of polymeric films. Stretch is carried out through two motor driven clamps in the machine direction and scissor-like clamps in the transverse direction keeping the sample width constant. The force information during film stretching process is recorded by a tension sensor and structural evolution can be obtained by in situ X-ray scattering technique. All parameters related to film stretching manufacturing, such as temperature, draw ratio, and stretching speed can be set independently, making the apparatus an effective method to explore the relationship between processing parameters and structure.

  16. In situ monitoring of biomolecular processes in living systems using surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Altunbek, Mine; Kelestemur, Seda; Culha, Mustafa

    2015-12-01

    Surface-enhanced Raman scattering (SERS) continues to strive to gather molecular level information from dynamic biological systems. It is our ongoing effort to utilize the technique for understanding of the biomolecular processes in living systems such as eukaryotic and prokaryotic cells. In this study, the technique is investigated to identify cell death mechanisms in 2D and 3D in vitro cell culture models, which is a very important process in tissue engineering and pharmaceutical applications. Second, in situ biofilm formation monitoring is investigated to understand how microorganisms respond to the environmental stimuli, which inferred information can be used to interfere with biofilm formation and fight against their pathogenic activity.

  17. In-situ measurement of processing properties during fabrication in a production tool

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D. E.; Haverty, P.; Hoff, M.; Loos, A. C.

    1988-01-01

    Progress is reported on the use of frequency-dependent electromagnetic measurements (FDEMs) as a single, convenient technique for continuous in situ monitoring of polyester cure during fabrication in a laboratory and manufacturing environment. Preliminary FDEM sensor and modeling work using the Loss-Springer model in order to develop an intelligent closed-loop, sensor-controlled cure process is described. FDEMs using impedance bridges in the Hz to MHz region is found to be ideal for automatically monitoring polyester processing properties continuously throughout the cure cycle.

  18. In-situ materials processing systems and bioregenerative life support systems interrelationships

    NASA Technical Reports Server (NTRS)

    Mignon, George V.; Frye, Robert J.

    1992-01-01

    The synergy and linkages between bioregenerative life support systems and the materials produced by in-situ materials processing systems was investigated. Such systems produce a broad spectrum of byproducts such as oxygen, hydrogen, processed soil material, ceramics, refractory, and other materials. Some of these materials may be utilized by bioregenerative systems either directly or with minor modifications. The main focus of this project was to investigate how these materials can be utilized to assist a bioregenerative life support system. Clearly the need to provide a sustainable bioregenerative life support system for long term human habitation of space is significant.

  19. Urine Stasis Predisposes to Urinary Tract Infection by an Opportunistic Uropathogen in the Megabladder (Mgb) Mouse

    PubMed Central

    Becknell, Brian; Mohamed, Ahmad Z.; Li, Birong; Wilhide, Michael E.; Ingraham, Susan E.

    2015-01-01

    Purpose Urinary stasis is a risk factor for recurrent urinary tract infection (UTI). Homozygous mutant Megabladder (Mgb-/-) mice exhibit incomplete bladder emptying as a consequence of congenital detrusor aplasia. We hypothesize that this predisposes Mgb-/- mice to spontaneous and experimental UTI. Methods Mgb-/-, Mgb+/-, and wild-type female mice underwent serial ultrasound and urine cultures at 4, 6, and 8 weeks to detect spontaneous UTI. Urine bacterial isolates were analyzed by Gram stain and speciated. Bladder stones were analyzed by x-ray diffractometry. Bladders and kidneys were subject to histologic analysis. The pathogenicity of coagulase-negative Staphylococcus (CONS) isolated from Mgb-/- urine was tested by transurethral administration to culture-negative Mgb-/- or wild-type animals. The contribution of urinary stasis to CONS susceptibility was evaluated by cutaneous vesicostomy in Mgb-/- mice. Results Mgb-/- mice develop spontaneous bacteriuria (42%) and struvite bladder stones (31%) by 8 weeks, findings absent in Mgb+/- and wild-type controls. CONS was cultured as a solitary isolate from Mgb-/- bladder stones. Bladders and kidneys from mice with struvite stones exhibit mucosal injury, inflammation, and fibrosis. These pathologic features of cystitis and pyelonephritis are replicated by transurethral inoculation of CONS in culture-negative Mgb-/- females, whereas wild-type animals are less susceptible to CONS colonization and organ injury. Cutaneous vesicostomy prior to CONS inoculation significantly reduces the quantity of CONS recovered from Mgb-/- urine, bladders, and kidneys. Conclusions CONS is an opportunistic uropathogen in the setting of urinary stasis, leading to enhanced UTI incidence and severity in Mgb-/- mice. PMID:26401845

  20. Permanent magnet with MgB2 bulk superconductor

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akiyasu; Ishihara, Atsushi; Tomita, Masaru; Kishio, Kohji

    2014-07-01

    Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging. The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demonstrate that 40-K-class metallic HTS magnesium diboride (MgB2) makes an excellent permanent bulk magnet, maintaining 3 T at 20 K for 1 week with an extremely high stability (<0.1 ppm/h). The magnetic field trapped in this magnet is uniformly distributed, as for single-crystalline neodymium-iron-boron. Magnetic hysteresis loop of the MgB2 permanent bulk magnet was detrmined. Because MgB2 is a simple-binary-line compound that does not contain rare-earth metals, polycrystalline bulk material can be industrially fabricated at low cost and with high yield to serve as strong magnets that are compatible with conventional compact cryocoolers, making MgB2 bulks promising for the next generation of Tesla-class permanent-magnet applications.

  1. Bacterial-fungal interactions enhance power generation in microbial fuel cells and drive dye decolourisation by an ex situ and in situ electro-Fenton process.

    PubMed

    Fernández de Dios, María Ángeles; del Campo, Araceli González; Fernández, Francisco Jesús; Rodrigo, Manuel; Pazos, Marta; Sanromán, María Ángeles

    2013-11-01

    In this work, the potential for sustainable energy production from wastes has been exploited using a combination fungus-bacterium in microbial fuel cell (MFC) and electro-Fenton technology. The fungus Trametes versicolor was grown with Shewanella oneidensis so that the bacterium would use the networks of the fungus to transport the electrons to the anode. This system generated stable electricity that was enhanced when the electro-Fenton reactions occurred in the cathode chamber. This configuration reached a stable voltage of approximately 1000 mV. Thus, the dual benefits of the in situ-designed MFC electro-Fenton, the simultaneous dye decolourisation and the electricity generation, were demonstrated. Moreover, the generated power was effectively used to drive an ex situ electro-Fenton process in batch and continuous mode. This newly developed MFC fungus-bacterium with an in situ electro-Fenton system can ensure a high power output and a continuous degradation of organic pollutants. PMID:24035817

  2. Bacterial-fungal interactions enhance power generation in microbial fuel cells and drive dye decolourisation by an ex situ and in situ electro-Fenton process.

    PubMed

    Fernández de Dios, María Ángeles; del Campo, Araceli González; Fernández, Francisco Jesús; Rodrigo, Manuel; Pazos, Marta; Sanromán, María Ángeles

    2013-11-01

    In this work, the potential for sustainable energy production from wastes has been exploited using a combination fungus-bacterium in microbial fuel cell (MFC) and electro-Fenton technology. The fungus Trametes versicolor was grown with Shewanella oneidensis so that the bacterium would use the networks of the fungus to transport the electrons to the anode. This system generated stable electricity that was enhanced when the electro-Fenton reactions occurred in the cathode chamber. This configuration reached a stable voltage of approximately 1000 mV. Thus, the dual benefits of the in situ-designed MFC electro-Fenton, the simultaneous dye decolourisation and the electricity generation, were demonstrated. Moreover, the generated power was effectively used to drive an ex situ electro-Fenton process in batch and continuous mode. This newly developed MFC fungus-bacterium with an in situ electro-Fenton system can ensure a high power output and a continuous degradation of organic pollutants.

  3. Impact of process temperature on GaSb metal-oxide-semiconductor interface properties fabricated by ex-situ process

    SciTech Connect

    Yokoyama, Masafumi Takenaka, Mitsuru; Takagi, Shinichi; Asakura, Yuji; Yokoyama, Haruki

    2014-06-30

    We have studied the impact of process temperature on interface properties of GaSb metal-oxide-semiconductor (MOS) structures fabricated by an ex-situ atomic-layer-deposition (ALD) process. We have found that the ALD temperature strongly affects the Al{sub 2}O{sub 3}/GaSb MOS interface properties. The Al{sub 2}O{sub 3}/GaSb MOS interfaces fabricated at the low ALD temperature of 150 °C have the minimum interface-trap density (D{sub it}) of ∼4.5 × 10{sup 13 }cm{sup −2} eV{sup −1}. We have also found that the post-metalization annealing at temperature higher than 200 °C degrades the Al{sub 2}O{sub 3}/GaSb MOS interface properties. The low-temperature process is preferable in fabricating GaSb MOS interfaces in the ex-situ ALD process to avoid the high-temperature-induced degradations.

  4. InSitu-Eye: oceanological and atmospheric data processing and analyzing system

    NASA Astrophysics Data System (ADS)

    Stepochkin, Igor E.; Salyuk, Pavel A.; Shmirko, Konstantin A.; Golik, Irina A.; Burov, Denis V.

    2014-11-01

    In this study we introduce brief description and the main approaches used in system development. System is devising with a participation of Pacific Oceanological Institute (FEB RAS), Institute of Automation and Control Processes (FEB RAS) and also Maritime State University, n.a. G.I. Nevelskoy. For many years research team of these institutions carried out a lot of field measurements and collected a lot of remote sensing data, using spectrophotometers, LIDARs, fluorometers. The primary goal of this development - bring all this data together to integrated database and design user-friendly interface to work with. "InSitu-Eye" will perform standard routine operations, such as sampling data according to certain parameters; gridding and timing of data; filtering and quality check of data; visualization. After setting system up and testing it will provide a benefit. At first it gives 24/7 access to "clean", checked "in-situ" data, ready for further research. Also presence of such system gives "converse effect" - it will become necessary to develop strict protocols for measurements carrying out and increase their quality. In future, "InSitu-Eye" can become a platform, connecting research teams for data keeping and exchange.

  5. Robotic-Controlled, Autonomous Friction Stir Welding Processes for In-Situ Fabrication, Maintenance, and Repair

    NASA Astrophysics Data System (ADS)

    Zhou, W.

    NASA s new vision of human and robotic missions to the Moon Mars and beyond will demand large and permanent infrastructures on the Moon and other planets including power plants communication towers human and biomass habitats launch and landing facilities fabrication and repair workshops and research facilities so that material utilization and product development can be carried out and subsisted in-situ The conventional approach of transporting pre-constructed fabricated structures from earth to the Moon planets will no longer be feasible due to limited lifting capacity and extremely high transportation costs associated with long duration space travel To minimize transport of pre-made large structures between earth and the Moon planets minimize crew time for the fabrication and assembly of infrastructures on the Moon planets and to assure crew safety and maintain quality during the operation there is a strong need for robotic capabilities for in-situ fabrication maintenance and repair Clearly development of innovative autonomous in-situ fabrication maintenance and repair technologies is crucial to the success of both NASA s unmanned preparation missions and manned exploration missions In-space material joining is not new to NASA Many lessons were learned from NASA s International Space Welding Experiment which employed the Electron Beam Welding process for space welding experiments Significant safety concerns related to high-energy beams arcing spatter elecromagnetic fields and molten particles were

  6. Enhancement of the high-magnetic-field critical current density of superconducting MgB2 by proton irradiation.

    PubMed

    Bugoslavsky, Y; Cohen, L F; Perkins, G K; Polichetti, M; Tate, T J; Gwilliam, R; Caplin, A D

    2001-05-31

    Magnesium diboride, MgB2, has a relatively high superconducting transition temperature, placing it between the families of low- and high-temperature (copper oxide based) superconductors. Supercurrent flow in MgB2 is unhindered by grain boundaries, making it potentially attractive for technological applications in the temperature range 20-30 K. But in the bulk material, the critical current density (Jc) drops rapidly with increasing magnetic field strength. The magnitude and field dependence of the critical current are related to the presence of structural defects that can 'pin' the quantized magnetic vortices that permeate the material, and a lack of natural defects in MgB2 may be responsible for the rapid decline of Jc with increasing field strength. Here we show that modest levels of atomic disorder induced by proton irradiation enhance the pinning of vortices, thereby significantly increasing Jc at high field strengths. We anticipate that either chemical doping or mechanical processing should generate similar levels of disorder, and so achieve performance that is technologically attractive in an economically viable way.

  7. Towards in-situ process monitoring in selective laser sintering using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Guan, Guangying; Lu, Zeng H.; Hirsch, Matthias; Goodridge, Ruth; Childs, David T. D.; Matcher, Stephen J.; Clare, Adam T.; Groom, Kristian M.

    2016-04-01

    Selective laser sintering (SLS) enables fast, flexible and cost-efficient production of parts directly from 3D CAD data. However, compared with more established machine tools, there is a marked lack of process monitoring and feedback control of key process variables to optimize production parameters in-situ. We apply optical coherence tomography (OCT) to evaluate components produced by SLS and suggest a route for its application in in-situ process monitoring within the SLS tool for real-time monitoring of the SLS process for assurance, or even dynamic correction of defects during the build. OCT is shown to be a viable technique for evaluation of both surface and sub-surface features built into a part either by design or from poor sintering or non-homogeneous powder spreading. We demonstrate detection and quantification of surface defects on a ~30 μm scale in a Polyamide (PA2200) part, resolving `built-in' fine features within a 200 to 400μm depth below the surface.

  8. Energy from true in situ processing of Antrim shale: Sampling and analytical systems

    NASA Astrophysics Data System (ADS)

    Pihlaja, R. K.

    1980-08-01

    Reliable on-line analysis of production gas composition is fundamental to the success of an in situ extraction experiment in Antrim shale. An automted sampling and analysis system designed to meet this need provided high quality analytical data for three extraction trials without a single day when no data were taken. The production gas samples were routinely analyzed by both gas chromatography and a bank of continuous on-line process gas analyzers. The process gas analyzers measured CO, CO2, total hydrocarbons and O2 continuously. The process gas analyzers were shown to be especially well suited for this application because of their fast response. The GC data provided itemized composition details as well as the independent check of process analyzer data. The combination of the two analytical techniques and automated data handling yielded a versatile and powerful system.

  9. In Situ Vitrification: Recent test results for a contaminated soil melting process

    SciTech Connect

    Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.

    1988-06-01

    In Situ Vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy and other clients for the stabilization of soils and sludges contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product that is similar to obsidian. In June 1987, a large-scale test of the process was completed at a transuranic- contaminated soil site. This constituted the first full-scale demonstration of the ISV process at an actual site. This paper summarizes the preliminary results of this test and describes the processes' potential adaptation to radioactive and hazardous chemical waste contaminated soils. 10 refs., 10 figs.

  10. In situ Resource Utilization for Processing of Metal Alloys on Lunar and Mars Bases

    NASA Astrophysics Data System (ADS)

    Stefanescu, D. M.; Grugel, R. N.; Curreri, P. A.

    1998-01-01

    Current plans for practical missions leading to a sustained human presence on our Moon and Mars rely on utilizing their in situ resources. Initially, resource availability must be assessed followed by the development of economically acceptable and technically feasible extractive processes. In regard to metals processing and fabrication, the lower gravity level on the Moon (0.125 g) and Mars (0.369 g) will dramatically change the presently accepted hierarchy of materials in terms of specific properties, a factor which must be understood and exploited. Furthermore, significant changes are expected in the behavior of liquid metals during processing. In metal casting, for example, mold filling and associated solidification processes have to be reevaluated. Finally, microstructural development and therefore material properties, presently being documented through ongoing research in microgravity science and applications, needs to be understood and scaled to the reduced gravity environments. These and other issues are addressed in this paper.

  11. Methods of producing alkylated hydrocarbons from an in situ heat treatment process liquid

    DOEpatents

    Roes, Augustinus Wilhelmus Maria; Mo, Weijian; Muylle, Michel Serge Marie; Mandema, Remco Hugo; Nair, Vijay

    2009-09-01

    A method for producing alkylated hydrocarbons is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce at least a second gas stream including hydrocarbons having a carbon number of at least 3. The first gas stream and the second gas stream are introduced into an alkylation unit to produce alkylated hydrocarbons. At least a portion of the olefins in the first gas stream enhance alkylation.

  12. In-situ observation of atomic self-organization processes in Xe nanocrystals embedded in Al.

    SciTech Connect

    Mitsuishi, K.; Song, M.; Furuya, K.; Birtcher, R. C.; Allen, C. W.; Donnelly, S. E.

    1998-03-10

    Self-organization processes in Xe nanocrystals embedded in Al are observed with in-situ high-resolution electron microscopy. Under electron irradiation, stacking fault type defects are produced in Xe nanocrystals. The defects recover in a layer by layer manner. Detailed analysis of the video reveals that the displacement of Xe atoms in the stacking fault was rather small for the Xe atoms at boundary between Xe and Al, suggesting the possibility of the stacking fault in Xe precipitate originating inside of precipitate, not at the Al/Xe interface.

  13. Rapid thermal processing chamber for in-situ x-ray diffraction

    SciTech Connect

    Ahmad, Md. Imteyaz; Van Campen, Douglas G.; Yu, Jiafan; Pool, Vanessa L.; Van Hest, Maikel F. A. M.; Toney, Michael F.; Fields, Jeremy D.; Parilla, Philip A.; Ginley, David S.

    2015-01-15

    Rapid thermal processing (RTP) is widely used for processing a variety of materials, including electronics and photovoltaics. Presently, optimization of RTP is done primarily based on ex-situ studies. As a consequence, the precise reaction pathways and phase progression during the RTP remain unclear. More awareness of the reaction pathways would better enable process optimization and foster increased adoption of RTP, which offers numerous advantages for synthesis of a broad range of materials systems. To achieve this, we have designed and developed a RTP instrument that enables real-time collection of X-ray diffraction data with intervals as short as 100 ms, while heating with ramp rates up to 100 °Cs{sup −1}, and with a maximum operating temperature of 1200 °C. The system is portable and can be installed on a synchrotron beamline. The unique capabilities of this instrument are demonstrated with in-situ characterization of a Bi{sub 2}O{sub 3}-SiO{sub 2} glass frit obtained during heating with ramp rates 5 °C s{sup −1} and 100 °C s{sup −1}, revealing numerous phase changes.

  14. Structure and properties of oxygen-containing thin films and bulk MgB2

    NASA Astrophysics Data System (ADS)

    Prikhna, T.; Shapovalov, A.; Goldacker, W.; Eisterer, M.; Kozyrev, A.; Shaternik, V.; Boutko, V.; Gusev, A.; Weber, H. W.; Karpets, M.; Basyuk, T.; Sverdun, V.; Moshchil, V.; Belogolovskiy, M.; Sergienko, N.

    2015-12-01

    A structural Auger spectroscopy study of MgB2 thin (∼140 nm) oxygen-containing polycrystalline films produced by magnetron sputtering and 99% dense MgB2 bulks synthesized at 2 GPa allows us to conclude that jc of MgB2 depends to a high extent on the amount and distribution of oxygen in the material matrix. jc reached 7.8-2.7 MA/cm2 below 1T at 20 K in the films and 0.3-0.9 MA/cm2 (depending on the boron used) in the bulks. The higher jc in MgB2 thin films can be associated with finer oxygen-enriched Mg-B-O inclusions and their higher density in the film structure compared to the bulk. Calculations of the total electron density of states (DOS) in MgB2, MgB1.75O0.25, MgB1.5O0.5 and MgBO showed that all the compounds are conductors with metal-like behaviour. The DOS is even higher in MgB1.5O0 5 than in MgB2 and the binding energy is similar. So, the experimentally found presence of some dissolved oxygen in MgB2 does not contradict its high SC performance. The introduction of a high amount of oxygen into the MgB2 structure does not dramatically reduce the material's Tc and allows obtaining highjc as observed in our MgB2 films and bulks.

  15. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2004-04-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this first quarterly report of our DoE funded research, we discuss the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. The formulation presented here for a first one-dimensional simulator will serve as the foundation for the development of a three-dimensional simulator that can handle realistic permeability heterogeneity. The development of the simulation tool will be supported by extensive laboratory experiments conducted to provide validation data, and to study effective variants of the combustion process. The preliminary investigation reported here shows how metallic salt additives can promote and sustain combustion by enhancing the oxidation and cracking of hydrocarbons.

  16. In situ vitrification: Test results for a contaminated soil-melting process

    SciTech Connect

    Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.

    1989-10-01

    In situ vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy to stabilize soils and sludges that are contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product similar to obsidian and basalt. In June 1987, a large-scale test of the process was completed at a transuranic-contaminated soil site. The test constituted the first full-scale demonstration of ISV at an actual site. This paper summarizes the results of that test and describes the potential adaptation of the process to radioactive and hazardous chemical waste-contaminated soils. 15 refs., 9 figs., 3 tabs.

  17. Adsorption of laminaribiose in an in-situ product recovery process

    NASA Astrophysics Data System (ADS)

    Waluga, Thomas; Scholl, Stephan

    2012-05-01

    With the decreasing availability of fossil carbon sources new synthesis routes for pharmaceuticals and finechemicals find growing interest. Higher oligosaccharide laminaribiose can be produced by enzymatic synthesis from inexpensive sucrose. For an economic process an in-situ product removal by adsorption is investigated. BEA 50 zeolite shows high potential for application due to its good adsorption properties. Isotherms show Langmuir behavior and adequate loadings of nearly 100 mg ṡ g-1 can be reached. Other intermediates formed during the process do not adsorb on this zeolite or show weaker adsorption. Further thermal desorption can be used to regain laminaribiose. However the use of BEA 50 zeolite needs a sophisticated desorption process because of the zeolites' high acidity which catalyzes the degradation of laminaribiose. Hence lower temperatures have to be used or combined with displacement desorption.

  18. Superconducting MgB2 flowers: growth mechanism and their superconducting properties

    NASA Astrophysics Data System (ADS)

    Seong, Won Kyung; Ranot, Mahipal; Lee, Ji Yeong; Yang, Cheol-Woong; Lee, Jae Hak; Oh, Young Hoon; Ahn, Jae-Pyoung; Kang, Won Nam

    2016-04-01

    We report for the first time the growth and the systematic study of the growth mechanism for flower-like MgB2 structures fabricated on the substrates for solid-state electronics by the hybrid physical-chemical vapor deposition (HPCVD) technique. The MgB2 flower has a width of 30 μm and a height of 10 μm. The superconductivity of MgB2 flowers was confirmed by a magnetization measurement, and the transition temperature is 39 K, which is comparable with high-quality bulk samples. The excellent current-carrying capability was demonstrated by MgB2 flowers. To understand the nucleation and growth mechanism of MgB2 flowers a very systematic study was performed by a high-resolution transmission electron microscope (HRTEM) and atom probe (AP) microscopy. The HRTEM revealed that the seed grain of a MgB2 flower has a [101¯0] direction, and the flower is composed of micro-columnar MgB2 grains having pyramidal tips and which are grown along the (0001) plane. A clear understanding of the growth mechanism for MgB2 flowers could lead to the growth of other low-dimensional MgB2 structures for superconducting electronic devices.

  19. MgB2 superconducting whiskers synthesized by using the hybrid physical-chemical vapor deposition.

    PubMed

    Wang, Yazhou; Zhuang, Chenggang; Gao, Jingyun; Shan, Xudong; Zhang, Jingmin; Liao, Zhimin; Xu, Hongjun; Yu, Dapeng; Feng, Qingrong

    2009-02-25

    In this work, MgB(2) whiskers were fabricated on a copper substrate by using the hybrid physical-chemical vapor deposition, which was one of the most effective ways to make high quality pure MgB(2) films, with the possible growth mechanism discussed. The whiskers are hexagonal and conelike and grow along the [0001] direction with a single-crystal structure. The onset transition temperature is approximately 39 K, which is among the best in the published nanostructure MgB(2) papers. Fabrication of nanoscale MgB(2) whiskers provides the fundamental understanding of the effect of dimensionality and size on superconductivity.

  20. Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bateni, Ali; Erdem, Emre; Repp, Sergej; Weber, Stefan; Somer, Mehmet

    2016-05-01

    Undoped and aluminum (Al) doped magnesium diboride (MgB2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB2. Above a certain level of Al doping, enhanced conductive properties of MgB2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites.

  1. Effect of Heat Treatment on the Microstructure and Properties of Deformation-Processed Cu-7Cr In Situ Composites

    NASA Astrophysics Data System (ADS)

    Liu, Keming; Jiang, Zhengyi; Zhou, Haitao; Lu, Deping; Atrens, Andrej; Yang, Yanling

    2015-11-01

    The effect of heat treatment on the microstructure, electrical conductivity, and tensile strength of deformation-processed Cu-7Cr in situ composites produced by thermo-mechanical processing was investigated. The Cr fibers in the Cu-7Cr in situ composite underwent coarsening, break-up, and spheroidization after exposure to elevated temperatures. The conductivity and tensile strength of the in situ composite first increased with increasing isochronal heat treatment temperature, reached a peak value, and decreased at higher temperatures. The isothermal heat treatment temperature was determined to be 625 °C. The Z ( Z is an optimization parameter to evaluate the service performance of deformation-processed Cu-based in situ composites) value of the deformation-processed Cu-7Cr in situ composite, at η = 7 ( η is a cumulative cold deformation strain) after the heat treatment at 625 °C for 1 h, reached the peak value of 3.46 × 107 MPa2 % International Annealed Copper Standard (IACS). The isochronal heat treatment time was determined to be 1 h. The following combination of conductivity and tensile strength of the deformation-processed Cu-7Cr in situ composite with a cumulative cold deformation strain of eight after isochronal aging treatments for 1 h could be attained respectively as (i) 76.0% IACS and 889 MPa; (ii) 76.8% IACS and 876 MPa; or (iii) 77.5% IACS and 779 MPa.

  2. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2004-07-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this third quarterly report of our DoE funded research, we continue the discussion of the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. Also, we show preliminary results for the one-dimensional in-situ combustion simulator, which will serve as the foundation for the development of a three-dimensional simulator that can handle realistic permeability heterogeneity. On the experimental side, the combustion kinetic apparatus and the combustion tube are now fully operational, and a series of successful combustion tube runs were performed that clearly showed additives allow combustion of poorly reactive oils. We have also started scanning electron microscope (SEM) analysis to investigate the sand-clay-salt mixtures that are used for combustion in which we focus on grain sizes, shapes, orientations, characteristic inter-structures, and element analysis.

  3. In situ ammonia analyzer using a near infrared diode laser for process control and environmental monitoring

    SciTech Connect

    Brand, J.; Fetzer, G.; Groff, K.

    1997-12-31

    An ammonia monitor designed for in situ smoke stack or exhaust duct applications is discussed. A probe composed of diffusion cell with protected multi-pass optical measurement cavity provides the optical interaction with the sample. Other components of the system include signal processing electronics and an embedded computer platform. This instrument is useful in a wide variety of ammonia monitoring and process control applications, particularly ammonia-based NO{sub x} control technologies, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). The in situ design eliminates sample handling problems, associated with extractive analysis of ammonia, such as sample handling line adsorption and heated sample trains and cells. The sensor technology developed for this instrument is second harmonic spectroscopy using a near infrared diode laser. Data collected during field trails involving both SCR and SNCR applications demonstrate the feasibility and robust operation of this instrument in traditionally problematic operating environments. The instrument can measure other gases by changing the wavelength, either by changing the diode operational set point or by changing the diode. In addition, with straightforward modification the instrument can measure multiple species.

  4. In-situ ammonia analyzer for process control and environmental monitoring

    NASA Astrophysics Data System (ADS)

    Monlux, Garth; Brand, Joel A.; Zmarzly, Patrick; Walker, M.; Groff, K. W.; Fetzer, Gregory J.; Goldstein, Neil; Bien, Fritz; Richtsmeier, Steven C.; Lee, Jamine

    1996-11-01

    An ammonia monitor designed for in situ smoke stack or exhaust duct applications is discussed here. A probe composed of a diffusion cell with a protected multipass optical measurement cavity provides the optical interaction with the sample. Other components of the system include signal processing electronics and an embedded PC104 computer platform. This instrument is useful in a wide variety of ammonia monitoring and process control applications, particularly ammonia-based NOx control technologies, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR). The in situ design eliminates sample handling problems, associated with extractive analysis of ammonia, such as sample line adsorption and heated sample trains and cells. The sensor technology exploited in this instrument is second harmonic spectroscopy using a near infrared diode laser. Data collected during field trials involving both SCR and SNCR applications demonstrate the feasibility and robust operation of this instrument in traditionally problematic operating environments. The instrument can measure other gases by changing the wavelength, either by changing the diode operational set point or by changing the diode. In addition, with straightforward modification the instrument can measure multiple species.

  5. In situ observation of elementary growth processes of protein crystals by advanced optical microscopy.

    PubMed

    Sazaki, Gen; Van Driessche, Alexander E S; Dai, Guoliang; Okada, Masashi; Matsui, Takuro; Otálora, Fermin; Tsukamoto, Katsuo; Nakajima, Kazuo

    2012-07-01

    To start systematically investigating the quality improvement of protein crystals, the elementary growth processes of protein crystals must be first clarified comprehensively. Atomic force microscopy (AFM) has made a tremendous contribution toward elucidating the elementary growth processes of protein crystals and has confirmed that protein crystals grow layer by layer utilizing kinks on steps, as in the case of inorganic and low-molecular-weight compound crystals. However, the scanning of the AFM cantilever greatly disturbs the concentration distribution and solution flow in the vicinity of growing protein crystals. AFM also cannot visualize the dynamic behavior of mobile solute and impurity molecules on protein crystal surfaces. To compensate for these disadvantages of AFM, in situ observation by two types of advanced optical microscopy has been recently performed. To observe the elementary steps of protein crystals noninvasively, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) was developed. To visualize individual mobile protein molecules, total internal reflection fluorescent (TIRF) microscopy, which is widely used in the field of biological physics, was applied to the visualization of protein crystal surfaces. In this review, recent progress in the noninvasive in situ observation of elementary steps and individual mobile protein molecules on protein crystal surfaces is outlined.

  6. Discrete magic angle turning system, apparatus, and process for in situ magnetic resonance spectroscopy and imaging

    DOEpatents

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Wind, Robert A.

    2009-05-19

    Described are a "Discrete Magic Angle Turning" (DMAT) system, devices, and processes that combine advantages of both magic angle turning (MAT) and magic angle hopping (MAH) suitable, e.g., for in situ magnetic resonance spectroscopy and/or imaging. In an exemplary system, device, and process, samples are rotated in a clockwise direction followed by an anticlockwise direction of exactly the same amount. Rotation proceeds through an angle that is typically greater than about 240 degrees but less than or equal to about 360 degrees at constant speed for a time applicable to the evolution dimension. Back and forth rotation can be synchronized and repeated with a special radio frequency (RF) pulse sequence to produce an isotropic-anisotropic shift 2D correlation spectrum. The design permits tubes to be inserted into the sample container without introducing plumbing interferences, further allowing control over such conditions as temperature, pressure, flow conditions, and feed compositions, thus permitting true in-situ investigations to be carried out.

  7. Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

    SciTech Connect

    Doshi, P.; Rohatgi, A.; Ropp, M.; Chen, Z.; Ruby, D.; Meier, D.L.

    1995-01-01

    Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J{sub 0}), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J{sub 0}.

  8. Process Design and Economics for the Conversion of Lignocellulosic Biomass to Hydrocarbon Fuels. Thermochemical Research Pathways with In Situ and Ex Situ Upgrading of Fast Pyrolysis Vapors

    SciTech Connect

    Dutta, Abhijit; Sahir, Asad; Tan, Eric; Humbird, David; Snowden-Swan, Lesley J.; Meyer, Pimphan; Ross, Jeff; Sexton, Danielle; Yap, Raymond; Lukas, John Lukas

    2015-03-01

    This report was developed as part of the U.S. Department of Energy’s Bioenergy Technologies Office’s efforts to enable the development of technologies for the production of infrastructurecompatible, cost-competitive liquid hydrocarbon fuels from biomass. Specifically, this report details two conceptual designs based on projected product yields and quality improvements via catalyst development and process integration. It is expected that these research improvements will be made within the 2022 timeframe. The two conversion pathways detailed are (1) in situ and (2) ex situ upgrading of vapors produced from the fast pyrolysis of biomass. While the base case conceptual designs and underlying assumptions outline performance metrics for feasibility, it should be noted that these are only two of many other possibilities in this area of research. Other promising process design options emerging from the research will be considered for future techno-economic analysis.

  9. Energy from true in situ processing of Antrim shale: preparation of an in situ retort bed by hydraulic fracturing

    SciTech Connect

    Peil, C.A.

    1980-05-01

    Under these specific field conditions, utilization of the natural tendency of the formation to fracture vertically provided the basis for this revised experiment. Observations made during hydrofracturing and permeability testing indicate that a complicated but extensive fracture system exists in the 100 series wells. An efficient and effective borehole loading system was developed after considerable effort. Borehole explosives improved permeability and communications significantly over that which existed before explosive fracturing. The use of hydrofractured and propped fractures was effective and dramatically demonstrated by cement traversing from one well to another. Fluid control remained a problem and would become more significant during any in situ retorting trials. The results of this experiment are encouraging when compared with those experienced in our front site test area. However, on the basis of better fluid control, overall communications and a wider range of operating pressures, the explosive underream and fracturing experiment was chosen as the site for the in situ extraction trial. No further work is planned on this task.

  10. Evaluation Of In Situ Steam-Injection Processes For Reduction Of Petroleum Compounds Within An Abandoned Canal

    EPA Science Inventory

    A conceptual approach of a novel application of in-situ thermal processes that would either use a steam injection process or a steam/surfactant injection process was considered to remediate petroleum contaminated sediment residing in an abandoned canal. Laboratory tests were c...

  11. Potential for in situ chemical oxidation of acid extractable organics in oil sands process affected groundwater.

    PubMed

    Sohrabi, V; Ross, M S; Martin, J W; Barker, J F

    2013-11-01

    The process of bitumen extraction from oil sands in Alberta, Canada leads to an accumulation of toxic acid-extractable organics (AEOs) in oil sands process water (OSPW). Infiltration of OSPW from tailings ponds and from their retaining sand dykes and subsequent transport towards surface water has occurred. Given the apparent lack of significant natural attenuation of AEOs in groundwater, remediation may be required. This laboratory study evaluates the potential use of unactivated persulfate and permanganate as in situ oxidation agents for remediation of AEOs in groundwater. Naphthenic acids (NAs; CnH2n+zO2), which are a component of the acutely toxic AEOs, were degraded by both oxidants in OSPW samples. Permanganate oxidation yielded some residual dissolved organic carbon (DOC) whereas persulfate mineralized the AEO compounds with less residual DOC. Acid-extractable organics from oxidized OSPW had essentially no Microtox toxicity.

  12. In Situ XRD Studies of the Process Dynamics During Annealing in Cold-Rolled Copper

    NASA Astrophysics Data System (ADS)

    Dey, Santu; Gayathri, N.; Bhattacharya, M.; Mukherjee, P.

    2016-09-01

    The dynamics of the release of stored energy during annealing along two different crystallographic planes, i.e., {111} and {220}, in deformed copper have been investigated using in situ X-ray diffraction measurements at 458 K and 473 K (185 °C and 200 °C). The study has been carried out on 50 and 80 pct cold-rolled Cu sheets. The microstructures of the rolled samples have been characterized using optical microscopy and electron backscattered diffraction measurements. The microstructural parameters were evaluated from the X-ray diffractogram using the Scherrer equation and the modified Rietveld method. The stored energy along different planes was determined using the modified Stibitz formula from the X-ray peak broadening, and the bulk stored energy was evaluated using differential scanning calorimetry. The process dynamics of recovery and recrystallization as observed through the release of stored energy have been modeled as the second-order and first-order processes, respectively.

  13. Strong and Biostable Hyaluronic Acid-Calcium Phosphate Nanocomposite Hydrogel via in Situ Precipitation Process.

    PubMed

    Jeong, Seol-Ha; Koh, Young-Hag; Kim, Suk-Wha; Park, Ji-Ung; Kim, Hyoun-Ee; Song, Juha

    2016-03-14

    Hyaluronic acid (HAc) hydrogel exhibits excellent biocompatibility, but it has limited biomedical application due to its poor biomechanical properties as well as too-fast enzymatic degradation. In this study, we have developed an in situ precipitation process for the fabrication of a HAc-calcium phosphate nanocomposite hydrogel, after the formation of the glycidyl methacrylate-conjugated HAc (GMHA) hydrogels via photo-cross-linking, to improve the mechanical and biological properties under physiological conditions. In particular, our process facilitates the rapid incorporation of calcium phosphate (CaP) nanoparticles of uniform size and with minimal agglomeration into a polymer matrix, homogeneously. Compared with pure HAc, the nanocomposite hydrogels exhibit improved mechanical behavior. Specifically, the shear modulus is improved by a factor of 4. The biostability of the nanocomposite hydrogel was also significantly improved compared with that of pure HAc hydrogels under both in vitro and in vivo conditions. PMID:26878437

  14. Nanomaterial processing for multifunctional patterned composites for in situ sensing applications

    NASA Astrophysics Data System (ADS)

    Melrose, Zachary R.

    The increasing performance demands on composite materials have stimulated the development of new approaches and manufacturing techniques to integrate various system functionalities within the composite structure. Opportunity exists to produce smart, self-sensing composites, by altering the microstructure of the composite where sensors can be patterned for assessing damage locality and severity. Introduction of nanomaterials into continuous fiber-reinforced composites either at the fiber/matrix interface or within the polymer matrix enables further tailoring of mechanical and electrical properties. Carbon nanotubes have been studied extensively for modifying the mechanical and physical properties of fiber composites. Recently graphene has generated scientific and technical interest due to potential lower raw material costs and ease of processing. This work studies graphene nano-platelet processing parameters to determine the suitability of graphene nanocomposites for in situ sensing applications. Processing parameters for optimizing the piezoresistive response of graphene nano-platelet composites for in situ sensing applications are determined and applied in for the development of a patterning media suitable for deposition onto glass fibers. A new approach to selectively modify the electrical properties of composite fibers is employed to selectively deposit carbon nanotube and graphene nano-platelet enhanced patterning media through an adapted screen printing process. These nano-modified depositions create hierarchical patterns of piezoresistive sensors as fully integrated components and form a distributed sensor network at the fiber/matrix interface. New analysis tools for resistance based sensing techniques are applied to nanocomposites and patterned unidirectional hybrid nanocomposites to assess damage onset and accumulation. The sensitivity of the electrical response for the graphene nano-platelet is compared with the electrical response of the carbon nanotube

  15. In situ diagnostics of the crystal-growth process through neutron imaging: application to scintillators

    PubMed Central

    Tremsin, Anton S.; Makowska, Małgorzata G.; Perrodin, Didier; Shalapska, Tetiana; Khodyuk, Ivan V.; Trtik, Pavel; Boillat, Pierre; Vogel, Sven C.; Losko, Adrian S.; Strobl, Markus; Kuhn, L. Theil; Bizarri, Gregory A.; Bourret-Courchesne, Edith D.

    2016-01-01

    Neutrons are known to be unique probes in situations where other types of radiation fail to penetrate samples and their surrounding structures. In this paper it is demonstrated how thermal and cold neutron radiography can provide time-resolved imaging of materials while they are being processed (e.g. while growing single crystals). The processing equipment, in this case furnaces, and the scintillator materials are opaque to conventional X-ray interrogation techniques. The distribution of the europium activator within a BaBrCl:Eu scintillator (0.1 and 0.5% nominal doping concentrations per mole) is studied in situ during the melting and solidification processes with a temporal resolution of 5–7 s. The strong tendency of the Eu dopant to segregate during the solidification process is observed in repeated cycles, with Eu forming clusters on multiple length scales (only for clusters larger than ∼50 µm, as limited by the resolution of the present experiments). It is also demonstrated that the dopant concentration can be quantified even for very low concentration levels (∼0.1%) in 10 mm thick samples. The interface between the solid and liquid phases can also be imaged, provided there is a sufficient change in concentration of one of the elements with a sufficient neutron attenuation cross section. Tomographic imaging of the BaBrCl:0.1%Eu sample reveals a strong correlation between crystal fractures and Eu-deficient clusters. The results of these experiments demonstrate the unique capabilities of neutron imaging for in situ diagnostics and the optimization of crystal-growth procedures. PMID:27275133

  16. High-resolution photoemission study of MgB2.

    PubMed

    Takahashi, T; Sato, T; Souma, S; Muranaka, T; Akimitsu, J

    2001-05-21

    We have performed high-resolution photoemission spectroscopy on MgB2 and observed opening of a superconducting gap with a narrow coherent peak. We found that the superconducting gap is s like with the gap value ( Delta) of 4.5+/-0.3 meV at 15 K. The temperature dependence (15-40 K) of the gap value follows well the BCS form, suggesting that 2Delta/k(B)T(c) at T = 0 is about 3. No pseudogap behavior is observed in the normal state. The present results strongly suggest that MgB2 is categorized into a phonon-mediated BCS superconductor in the weak-coupling regime.

  17. Evidence for two superconducting gaps in MgB2.

    PubMed

    Chen, X K; Konstantinovic, M J; Irwin, J C; Lawrie, D D; Franck, J P

    2001-10-01

    We have measured the Raman spectra of polycrystalline MgB2 from 25 to 1200 cm(-1). A superconductivity-induced redistribution in the electronic Raman continuum was observed. Two pair-breaking peaks appear in the spectra, suggesting the presence of two superconducting gaps. The measured spectra were analyzed using a quasi-two-dimensional model in which two s-wave superconducting gaps open on two sheets of Fermi surface. For the gap values we have obtained Delta(1) = 22 cm(-1) ( 2.7 meV) and Delta(2) = 50 cm(-1) ( 6.2 meV). Our results suggest that a conventional phonon-mediated pairing mechanism occurs in the planar boron sigma bands and is responsible for the superconductivity of MgB2.

  18. Active Protection of an MgB2 Test Coil

    PubMed Central

    Park, Dong Keun; Hahn, Seungyong; Bascuñán, Juan; Iwasa, Yukikazu

    2011-01-01

    This paper presents results of a study, experimental and computational, of a detect-and-activate-the-heater protection technique applied to a magnesium diboride (MgB2) test coil operated in semi-persistent mode. The test coil with a winding ID of 25 cm and wound with ~500-m long reacted MgB2 wire was operated at 4.2 K immersed in a bath of liquid helium. In this active technique, upon the initiation of a “hot spot” of a length ~10 cm, induced by a “quench heater,” a “protection heater” (PH) of ~600-cm long planted within the test coil is activated. The normal zone created by the PH is large enough to absorb the test coil’s entire initial stored energy and still keeps the peak temperature within the winding below ~260 K. PMID:22081754

  19. Superconductivity in MgB2 irradiated with energetic protons

    NASA Astrophysics Data System (ADS)

    Sandu, Viorel; Craciun, Liviu; Ionescu, Alina Marinela; Aldica, Gheorghe; Miu, Lucica; Kuncser, Andrei

    2016-09-01

    A series of MgB2 samples were irradiated with protons of 11.3 and 13.2 MeV. Magnetization data shows an insignificant reduction of the critical temperatures but a continuous decrease of the Meissner fraction with increasing fluence or energy. All samples show a consistent improvement of the critical current density compared to the virgin sample and an increase of the pinning energy at high fields as resulted from relaxation data.

  20. Enhancement in the critical current density of C-doped MgB2 wire using a polyacrylic acid dopant.

    PubMed

    Lee, Seung Muk; Hwang, Soo Min; Lee, Chang Min; Kim, Won; Joo, Jinho; Lim, Jun Hyung; Kim, Chan-Joong; Hong, Gye-Won

    2012-02-01

    C-doped MgB2 wires were fabricated from a polyacrylic acid (PAA) using a conventional in-situ PIT technique. The effects of the PAA content on the lattice parameter, microstructure, critical temperature (Tc) and critical current density (Jc) were examined. With increasing PAA content, the amount of MgO in the sample increased but the crystallinity, a-axis lattice parameter, and Tc of MgB2 wires decreased, indicating that the C that decomposed from PAA during heat treatment had substituted for B. All doped samples exhibited a higher Jc than the undoped sample at high magnetic field, and the Jc(B) property improved with increasing PAA content: for the 7 wt% doped sample, the Jc was approximately 3-times higher than that of the pristine sample (1.28 kA/cm2 vs. 3.43 kA/cm2) at 5 K and 6.6 T. The improved Jc(B) of the doped sample was attributed to the decreased grain size, enlarged lattice distortion and increased C doping level.

  1. Effect of heat treatment temperature on superconducting performance of B 4C added MgB 2/Nb conductors

    NASA Astrophysics Data System (ADS)

    Viljamaa, J.; Kario, A.; Dobročka, E.; Reissner, M.; Kulich, M.; Kováč, P.; Häßler, W.

    2012-02-01

    A previously observed enhancing effect of addition of 10 wt.% of B 4C on critical current density ( Jc) dependence on magnetic flux density ( B) in MgB 2 superconductors is examined here in more detail. Nb sheathed in situ MgB 2 monofilamentary Powder-in-Tube (PIT) samples are prepared with the 10 wt.% addition of boron carbide. The samples are heat treated at different temperatures, namely at 650, 700, 750, and 800 °C for 30 min. The phases and lattice parameters of the samples are studied using X-ray Diffraction (XRD). The amount of B 4C does not decrease from the initial amount with increasing heat treatment temperature ( Tht) but instead increases. This indicates that some of the Mg from the precursor reacts with the Nb sheath. Magnetic Jc( B) characteristics are obtained at several temperatures in external B in a Vibrating Sample Magnetometer (VSM). The magnetic and transport Jc( B) results disagree with each other which can be explained by unsuitability of Nb as the sheath with higher Tht. From these results, also pinning force densities ( Fp) are calculated. No effect on pinning mechanism of B 4C added samples is observed by the heat treatment conditions. Resistance dependencies on temperature are also measured in a Physical Properties Measurement System (PPMS). Mg deficiency with high Tht is supported by these measurements.

  2. Energy from true in situ processing of Antrim shale: preparation of a cavity by chemical underreaming

    SciTech Connect

    Peil, C.A.; Cochran, G.A.

    1980-04-01

    The contract between the Dow Chemical Company and the Department of Energy to investigate the feasibility of recovery of energy from the Antrim shale by an in situ process includes a task titled, In Situ Fracturing and Assessment. This task required Dow to conduct and evaluate three fracturing techniques: hydraulic fracturing followed by explosive fracturing; chemical underream followed by explosive fracturing; and explosive underream and fracturing. The work carried out in the chemical underream subtask is summarized. Two distinctly different field methods were attempted. Hydrochloric acid treatment in the limestone section resulted in creating a cavity less than of the expected size. An attempt to produce a horizontal fracture in the limestone failed to establish the communication required to solution mine the limestone section between the injection and four production wells. Communication between the wells was an essential ingredient for success. In the second field trial, not having achieved this, neither the acidization or the originally planned explosive fracturing experiments were attempted. It was concluded that with current technology applied to these particular field conditions, the other two techniques offered the best short-term potential for success.

  3. STANFORD IN-SITU HIGH RATE YBCO PROCESS: TRANSFER TO METAL TAPES AND PROCESS SCALE UP

    SciTech Connect

    Malcolm R. Beasley; Robert H.Hammond

    2009-04-14

    Executive Summary The materials science understanding of high rate low cost processes for Coated Conductor will benefit the application to power utilities for low loss energy transportation and power generation as well for DOD applications. The research in this program investigated several materials processing approaches that are new and original, and are not being investigated elsewhere. This work added to the understanding of the material science of high rate PVD growth of HTSC YBCO assisted by a liquid phase. A new process discovered uses amorphous glassy precursors which can be made at high rate under flexible conditions of temperature and oxygen, and later brought to conditions of oxygen partial pressure and temperature for rapid conversion to YBCO superconductor. Good critical current densities were found, but further effort is needed to optimize the vortex pinning using known artificial inclusions. A new discovery of the physics and materials science of vortex pinning in the HTSC system using Sm in place of Y came at growth at unusually low oxygen pressure resulting in clusters of a low or non superconducting phase within the nominal high temperature phase. The driving force for this during growth is new physics, perhaps due to the low oxygen. This has the potential for high current in large magnetic fields at low cost, applicable to motors, generators and transformers. The technical demands of this project were the motivation for the development of instrumentation that could be essential to eventual process scale up. These include atomic absorption based on tunable diode lasers for remote monitoring and control of evaporation sources (developed under DARPA support), and the utility of Fourier Transform Infrared Reflectivity (FTIR) for aid in the synthesis of complex thin film materials (purchased by a DURIP-AFOSR grant).

  4. Understanding aquatic microbial processes using EEM's and in-situ fluorescence sensors

    NASA Astrophysics Data System (ADS)

    Fox, Bethany; Attridge, John; Rushworth, Cathy; Cox, Tim; Anesio, Alexandre; Reynolds, Darren

    2015-04-01

    The diverse origin of dissolved organic matter (DOM) in aquatic systems is well documented within the literature. Previous literature indicates that coloured dissolved organic matter (CDOM) is, in part, transformed by aquatic microbial processes, and that dissolved organic material derived from a microbial origin exhibits tryptophan-like fluorescence. However, this phenomenon is not fully understood and very little data is available within the current literature. The overall aim of our work is to reveal the microbial-CDOM interactions that give rise to the observed tryptophan-like fluorescence. The work reported here investigates the microbial processes that occur within freshwater aquatic samples, as defined by the biochemical oxygen demand (BOD) test, as a function of the T1 peak (λex/em 280/330-370 nm). A series of standard water samples were prepared using glucose, glutamic acid, BOD dilution water and a bacterial seed (Cole-Parmer BOD microbe capsules). Samples were spiked with CDOM (derived from an environmental water body) and subjected to time resolved BOD analysis and as excitation-emission fluorescence spectroscopy. All EEM spectral data was interrogated using parallel factor analysis (PARAFAC) in an attempt to determine the presence and dominance (relative intensities) of the CDOM-related and T1-related fluorophores within the samples. In-situ fluorescence sensors (Chelsea Technologies Group Ltd.) were also used to monitor the T1 fluorescence peak (UviLux Tryptophan) and the CDOM fluorescence peak (UviLux CDOM) during experiments. Tryptophan-like fluorescence was observed (albeit transient) in both spiked and un-spiked standard water samples. By furthering our understanding of aquatic organic matter fluorescence, its origin, transformation, fate and interaction with aquatic microbiological processes, we aim to inform the design of a new generation in-situ fluorescence sensor for the monitoring of aquatic ecosystem health.

  5. Modeling and Analysis of the Reverse Water Gas Shift Process for In-Situ Propellant Production

    NASA Technical Reports Server (NTRS)

    Whitlow, Jonathan E.

    2000-01-01

    This report focuses on the development of mathematical models and simulation tools developed for the Reverse Water Gas Shift (RWGS) process. This process is a candidate technology for oxygen production on Mars under the In-Situ Propellant Production (ISPP) project. An analysis of the RWGS process was performed using a material balance for the system. The material balance is very complex due to the downstream separations and subsequent recycle inherent with the process. A numerical simulation was developed for the RWGS process to provide a tool for analysis and optimization of experimental hardware, which will be constructed later this year at Kennedy Space Center (KSC). Attempts to solve the material balance for the system, which can be defined by 27 nonlinear equations, initially failed. A convergence scheme was developed which led to successful solution of the material balance, however the simplified equations used for the gas separation membrane were found insufficient. Additional more rigorous models were successfully developed and solved for the membrane separation. Sample results from these models are included in this report, with recommendations for experimental work needed for model validation.

  6. Hydrous pyrolysis/oxidation process for in situ destruction of chlorinated hydrocarbon and fuel hydrocarbon contaminants in water and soil

    DOEpatents

    Knauss, Kevin G.; Copenhaver, Sally C.; Aines, Roger D.

    2000-01-01

    In situ hydrous pyrolysis/oxidation process is useful for in situ degradation of hydrocarbon water and soil contaminants. Fuel hydrocarbons, chlorinated hydrocarbons, polycyclic aromatic hydrocarbons, petroleum distillates and other organic contaminants present in the soil and water are degraded by the process involving hydrous pyrolysis/oxidation into non-toxic products of the degradation. The process uses heat which is distributed through soils and water, optionally combined with oxygen and/or hydrocarbon degradation catalysts, and is particularly useful for remediation of solvent, fuel or other industrially contaminated sites.

  7. Energy from the in situ processing Antrim shale: process equipment used in the extraction trials

    SciTech Connect

    Murdick, D.A.

    1980-08-01

    As one phase of the 1976 contract between The Dow Chemical Company and the US Department of Energy investigating Antrim shale, three extraction trials were made at the shale research site at Peck, MI. This report is an overview of the process equipment used in those extraction trials. Equipment discussed in this report are: the air and nitrogen handling equipment, the methane fuel supply equipment, the field instrumentation, the flare, the well drying equipment, the control room and safety related equipment. After various problems related to each piece of equipment were solved, the equipment worked very well as a total unit. This functioning of the above ground equipment allowed the research group to focus most of its effort on the experimental problems encountered in the Antrim shale layer.

  8. In situ observation of deformation processes in nanocrystalline face-centered cubic metals

    PubMed Central

    Kobler, Aaron; Brandl, Christian; Hahn, Horst

    2016-01-01

    Summary The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline PdxAu1− x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin–twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains. PMID:27335747

  9. In situ analyses on negative ions in the indium-gallium-zinc oxide sputtering process

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo

    2013-07-01

    The origin of negative ions in the dc magnetron sputtering process using a ceramic indium-gallium-zinc oxide target has been investigated by in situ analyses. The observed negative ions are mainly O{sup -} with energies corresponding to the target voltage, which originates from the target and barely from the reactive gas (O{sub 2}). Dissociation of ZnO{sup -}, GaO{sup -}, ZnO{sub 2}{sup -}, and GaO{sub 2}{sup -} radicals also contributes to the total negative ion flux. Furthermore, we find that some sputtering parameters, such as the type of sputtering gas (Ar or Kr), sputtering power, total gas pressure, and magnetic field strength at the target surface, can be used to control the energy distribution of the O{sup -} ion flux.

  10. In situ observation of deformation processes in nanocrystalline face-centered cubic metals.

    PubMed

    Kobler, Aaron; Brandl, Christian; Hahn, Horst; Kübel, Christian

    2016-01-01

    The atomistic mechanisms active during plastic deformation of nanocrystalline metals are still a subject of controversy. The recently developed approach of combining automated crystal orientation mapping (ACOM) and in situ straining inside a transmission electron microscope was applied to study the deformation of nanocrystalline Pd x Au1- x thin films. This combination enables direct imaging of simultaneously occurring plastic deformation processes in one experiment, such as grain boundary motion, twin activity and grain rotation. Large-angle grain rotations with ≈39° and ≈60° occur and can be related to twin formation, twin migration and twin-twin interaction as a result of partial dislocation activity. Furthermore, plastic deformation in nanocrystalline thin films was found to be partially reversible upon rupture of the film. In conclusion, conventional deformation mechanisms are still active in nanocrystalline metals but with different weighting as compared with conventional materials with coarser grains. PMID:27335747

  11. In-situ monitoring the realkalisation process by neutron diffraction: Electroosmotic flux and portlandite formation

    SciTech Connect

    Castellote, Marta . E-mail: martaca@ietcc.csic.es; Llorente, Irene; Andrade, Carmen; Turrillas, Xavier; Alonso, Cruz; Campo, Javier

    2006-05-15

    Even though the electroosmotic flux through hardened cementitious materials during laboratory realkalisation trials had been previously noticed, it has never been in-situ monitored, analysing at the same time the establishment of the electroosmotic flux and the microstructure changes in the surroundings of the rebar. In this paper, two series of cement pastes, cast with CEM I and CEM I substituted in a 35% by fly ash, previously carbonated at 100% CO{sub 2}, were submitted to realkalisation treatments followed on line by simultaneous acquisition of neutron diffraction data. As a result, it has been possible to confirm the electroosmosis as the driving force of carbonates towards the rebar and to determine the range of pH in the anolyte in which most of the relevant electroosmotic phenomena takes place. On the other hand, the behaviour of the main crystalline phases involved in the process has been monitored during the treatment, with the precipitation of portlandite as main result.

  12. In-situ surface contamination removal and cool-down process of the DEAP-3600 experiment

    NASA Astrophysics Data System (ADS)

    Giampa, Pietro; DEAP Collaboration

    2016-05-01

    The DEAP-3600 experiment is a single-phase detector that uses 3600 Kg of liquid argon to search for Dark Matter at SNOLAB, Sudbury, Canada, 6800 ft. underground. The projected sensitivity to the spin-independent WIMP-nucleon cross-section is 10-46 cm2 for a WIMP mass of 100 GeV. A key experimental requirement is the reduction of any possible source of background that would mimic a Dark Matter signal This document will review how radiogenic surface backgrounds were reduced in-situ by removing 500 microns of acrylic from the innermost part of the detector with a resurfacing robot. Furthermore it will review the transient cool-down process of the experiment, necessary to reach cryogenic operating temperature.

  13. Tracking the catalyzed growth process of nanowires by in situ x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Kirkham, Melanie; Wang, Zhong Lin; Snyder, Robert L.

    2010-07-01

    Quasi-one-dimensional nanostructures of silicon, oxides, and other materials show great promise for a variety of applications. These nanostructures are commonly grown using metal catalyst nanoparticles. This paper investigates the growth mechanism of Au-catalyzed Si nanowires through in situ x-ray diffraction, and the results are compared to previously studied Au-catalyzed ZnO nanorods. The Si nanowires were found to grow from molten catalyst particles, however, the ZnO nanorods were found to grow from solid catalyst particles through a surface diffusion process. From this comparison, the relative bonding types of the catalyst and source material are determined to have a significant effect on the growth mechanism.

  14. Sustained release of risperidone from biodegradable microspheres prepared by in-situ suspension-evaporation process.

    PubMed

    An, Taekun; Choi, Juhyuen; Kim, Aram; Lee, Jin Ho; Nam, Yoonjin; Park, Junsung; Sun, Bo kyung; Suh, Hearan; Kim, Cherng-ju; Hwang, Sung-Joo

    2016-04-30

    Risperidone-loaded poly (D,L-lactide-co-glycolide) (PLGA) microspheres were prepared with a suspension-evaporation process with an aqueous suspension containing an in situ-formed aluminum hydroxide inorganic gel (SEP-AL process) and evaluated for encapsulation efficiency, particle size, surface morphology, glass transition temperature, in vitro drug release profile, and in vivo behavior. The SEP-AL microspheres were compared with conventional oil-in-water (O/W) emulsion solvent evaporation method using polyvinylalcohol (PVA) as an emulsifier (CP-PVA process). The microspheres were spherical in shape. DSC measurements showed that risperidone crystallinity was greatly reduced due to the homogeneous distribution of risperidone in PLGA microspheres. In vitro drug release profile from the microspheres showed a sigmoidal pattern of negligible initial burst up to 24h and minimal release (time-lag) for 7 days. After the lag phase, slow release took a place up to 25 days and then rapid release occurred sharply for 1 week. In vivo rat pharmacokinetic profile from the microspheres showed very low blood concentration level at the initial phase (up to 24h) followed by the latent phase up to 21 days. At the 3rd week, main phase started and the blood concentration of the drug increased up to the 5th week, and then gradually decreased. The risperidone-loaded PLGA microspheres produced by SEP-AL process showed excellent controlled release characteristics for the effective treatment of schizophrenia patients. PMID:26899975

  15. In situ treatment of mixed contaminants in groundwater: Review of candidate processes

    SciTech Connect

    Korte, N.E.; Siegrist, R.L.; Ally, M.

    1994-10-01

    This document describes the screening and preliminary evaluation of candidate treatment for use in treating mixed contaminants volatile organic compounds (VOCs) and radionuclides in groundwater. Treating mixed contaminants presents unusual difficulties. Typically, VOCs are the most abundant contaminants, but the presence of radionuclides results in additional health concerns that must be addressed, usually by a treatment approach different from that used for VOCs. Furthermore, the presence of radionuclides may yield mixed solid wastes if the VOCs are treated by conventional means. These issues were specifically addressed in the evaluation of candidate treatment processes for testing in this program. Moreover, because no research or early development of a particular process would be performed, the technology review also focused on technologies that could be readily adapted and integrated for use with mixed contaminants. The objective is to couple emerging or available processes into treatment modules for use in situ. The three year project, to be completed in September 1996, includes a full-scale field demonstration. The findings reported in this document encompass all activities through the treatment process evaluations.

  16. Properties of MgB2 films deposited on single crystal Ag layers

    NASA Astrophysics Data System (ADS)

    Liu, Z. H.; Wei, Y. K.; Zhang, C.; Feng, Q. R.; Ma, P.; Wang, Y.

    2014-04-01

    We have recently developed a method to deposit MgB2 thin films on single crystal Ag layers, and found that thin Ag layers reduced the the superconductivity of MgB2 not much, which may be a possible material to fabricate MgB2 SNS Josephson junctions. The single crystal Ag layers were deposited on (0 0 0 1) SiC substrates, and then the MgB2 thin films were deposited on the Ag layers. All the measurements included the XRD, M-T and M-H curves. The transition temperature of MgB2 films decreases from 39 K to 37 K, while the thickness of Ag layers grows from 0 to 20 nm, and the critical current density at 4.2 K decreases from 1.76 MA/cm2 to 1.24 MA/cm2, too.

  17. Doping effect of nano-diamond on superconductivity and flux pinning in MgB2

    NASA Astrophysics Data System (ADS)

    Cheng, C. H.; Zhang, H.; Zhao, Y.; Feng, Y.; Rui, X. F.; Munroe, P.; Zeng, H. M.; Koshizuka, N.; Murakami, M.

    2003-10-01

    The doping effect of diamond nanoparticles on the superconducting properties of MgB2 bulk material has been studied. It is found that the superconducting transition temperature Tc of MgB2 is suppressed by the diamond doping, however, the irreversibility field Hirr and the critical current density Jc are systematically enhanced. Microstructural analysis shows that the diamond-doped MgB2 superconductor consists of tightly-packed MgB2 nano-grains (~50-100 nm) with highly dispersed and uniformly distributed diamond nanoparticles (~10-20 nm) inside the grains. The high density of dislocations and diamond nanoparticles may be responsible for the enhanced flux pinning in the diamond-doped MgB2.

  18. Energy from true in situ processing of Antrim shale: sampling and analytical systems

    SciTech Connect

    Pihlaja, R.K.

    1980-08-01

    Reliable on-line analysis of production gas composition is fundamental to the success of an in situ extraction experiment in Antrim shale. An automated sampling and analysis system designed to meet this need has provided high quality analytical data for three extraction trials without a single day when no data were taken. The production gas samples were routinely analyzed by both gas chromatography (GC) and a bank of continuous on-line process gas analyzers. The GC's analyzed for H/sub 2/, O/sub 2/ + Ar, N/sub 2/, CO, CO/sub 2/, SO/sub 2/, H/sub 2/S, individual C/sub 1/ - C/sub 5/ hydrocarbon species, and lumped C/sub 6/ + hydrocarbon species, each analysis requiring up to an hour to run. The process gas analyzers measured CO, CO/sub 2/, total hydrocarbons (% vol CH/sub 4/ equivalent), and O/sub 2/ continuously. The process gas analyzers were shown to be especially well suited for this application because of their fast response. The GC data provided itemized composition details as well as an independent check of process analyzer data. Sample selection, data collection and processing from both the GC's and process gas analyzers was handled by a Perkin Elmer Sigma-10 minicomputer. The combination of the two analytical techniques and automated data handling yielded a versatile and powerful system. The production gas sampling system demonstrated the feasibility of transmitting a properly treated gas sample through a long (1000 ft) 1/8'' diameter sample line. The small bore tubing allowed the analytical instruments to be located a safe distance away from the well heads and yet maintain a reasonably short sample transport lag time without handling large volumes of gas.

  19. In-situ measurements of bottom boundary layer processes in the deep South China Sea

    NASA Astrophysics Data System (ADS)

    Xu, J.; Li, J.; Zhang, Y.; Zhao, Y.; Liu, Z.; Ferreira, J. C. T.; Tate, G.

    2014-12-01

    As part of the South China Sea Deep project, we deployed a free-ascending tripod (FAT) on the sea floor of northern South China Sea at a water depth of 1900 m. During the 5-month deployment, the tripod hosted a suite of acoustic and optical oceanographic instruments that simultaneously measured time-series of 3-D velocity structure of the near bottom flows, temperature and salinity, water turbidity (sediment concentration), and particle size variations. A camera system and an acoustic altimeter closely monitored fine scale changes of the sea floor that could have resulted from either physical processes (erosion/deposition) or biological activities. Our goal of the tripod work, first-ever such study in South China Sea, along with several subsurface moorings that were also collecting flow and sedimentological data in the area, was to investigate the bottom boundary layer (BBL) processes and the regional deep current circulation surrounding a large body of sediment deposit whose formation mechanism and origins of sediment are still unclear. In addition, the tripod instruments were set up to capture the in-situ BBL signature of passing "benthic storms" that are believed to be the most important BBL processes in deep ocean. This presentation also includes a brief description of the technological advances implemented in the FAT deep-water tripod.

  20. EXPERIMENTAL INVESTIGATION AND HIGH RESOLUTION SIMULATOR OF IN-SITU COMBUSTION PROCESSES

    SciTech Connect

    Margot Gerritsen; Anthony R. Kovscek

    2005-02-01

    Accurate simulation of in-situ combustion processes is computationally very challenging because the spatial and temporal scales over which the combustion process takes place are very small. In this fifth quarterly report of our DoE funded research, we continue the discussion of the design of a new simulation tool based on an efficient Cartesian Adaptive Mesh Refinement technique that allows much higher grid densities to be used near typical fronts than current simulators. We have now developed an appropriate upscaling technique for our grids, based on the local-global upscaling approach. We show preliminary results on two-dimensional test cases. On the experimental side, we continued experiments to measure the rates and kinetics of combustion in the presence and absence of metallic additives. In this quarter, we developed a better understanding of the cation replacing power of the various additives that affect combustion performance positively, and obtained a preliminary reactivity series. We also resumed our experimental investigation into the cyclic solvent-combustion process using crude oil from the Hamaca Region of Venezuela. Various measurements were made including oxygen consumption as a function of temperature. Preliminary results show that the temperatures for the onset of combustion are a function of the solvent injected.

  1. Electrochemical differential photoacoustic cell to study in situ the growing process of porous materials.

    PubMed

    Gutiérrez, Adriana; Giraldo, Jairo; Velázquez-Hernández, Rubén; Mendoza-López, Maria Luisa; Espinosa-Arbeláez, Diego G; del Real, Alicia; Rodríguez-García, Mario E

    2010-01-01

    In order to study in situ the growing process of porous materials, a new electrochemical differential photoacoustic cell (DPC) was developed. This system allows to obtain the thermal signals coming from the growing process of the pores without the external noise component. The DPC is a good system to growth porous silicon and study their growing process with reproducibility. The porous silicon samples were obtained by using electrochemical etching of (100) n-type silicon wafers with different nominal resistivity values in the range of 1-25 Omega cm. The samples were formed in a solution of hydrofluoric acid and ethanol having a composition ratio of 1:1 in volume with etching voltage of 10 V and an etching time of 2 min using back illumination provided by a laser beam with a wavelength of 808 nm. The porous samples were characterized by means of Raman microscopy, x-ray diffraction, and scanning electron microscopy. The crystallite sizes of the samples were obtained through the analysis of the micro-Raman spectra using a phonon confinement model, and the analysis of the x-ray diffractograms.

  2. The size effect on solidification in eutectic bismuth-tin (Bi-Sn) nanowires by in-situ annealing processes.

    PubMed

    Chen, Shih-Hsun; Wang, Chiu-Yen; Chen, Lih-Juann; Liu, Tzeng-Feng; Chaol, Chuen-Guang

    2010-10-01

    The size effects on solidification and the formation mechanism of the segmented eutectic Bi-43Sn nanowires during in situ annealing have been investigated. A directional solidification along the wire axis limits the segmented eutectic nanowire to arrange axially during the in situ annealing processes due to directional solidification. In 70 nm nanowires, the small size confines the convection in liquid, which results in differences in the microstructure and composition profiles between 70 and 200 nm nanowires. In the vacuum hydraulic pressure injection process, the directional cooling helps the formation of single crystal, and the isotropic solidification leads to polycrystalline microstructure.

  3. Volatile magnesium octahydrotriborate complexes as potential CVD precursors to MgB2. Synthesis and characterization of Mg(B3H8)2 and its etherates.

    PubMed

    Kim, Do Young; Yang, Yu; Abelson, John R; Girolami, Gregory S

    2007-10-29

    The solid-state reaction of MgBr2 and NaB3H8 at 20 degrees C, followed by sublimation at 80 degrees C and 0.05 Torr, affords Mg(B3H8)2 as a white solid. Similar reactions with MgBr2(Et2O) and MgBr2(Me2O)1.5 afford the crystalline ether adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2, respectively. In contrast, reactions of MgBr2 with NaB3H8, the presence of excess solvent result in the formation of nonvolatile, probably ionic, magnesium compounds of the type [MgLx][B3H8]2. The adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are the first crystallographically characterized magnesium complexes of the B3H8- ligand; in both structures, the magnesium center adopts a distorted cis-octahedral geometry with two bidentate B3H8 groups and two Et2O ligands. Owing to their volatility, Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are potential precursors for the deposition of MgB2 thin films, although preliminary efforts to employ them as chemical vapor deposition sources produce boron-rich MgBx films instead, with x approximately 7. Finally, the synthesis and structure of Cp2Mg(thf) are described: this mono-thf adduct of Cp2Mg bears two eta5-Cp groups, unlike other Lewis base adducts of Cp2Mg, which contain one eta5-Cp group and one eta1- or eta2-Cp group.

  4. Laser induced infrared spectral shift of the MgB2:Cr superconductor films.

    PubMed

    AlZayed, N S; Kityk, I V; Soltan, S; El-Naggar, A M; Shahabuddin, M

    2015-02-01

    During illumination of the MgB2:Cr2O3 films it was established substantial spectral shift of the infrared spectra in the vicinity of 20-50cm(-1). The excitations were performed by nanosecond Er:glass laser operating at 1.54μm and by microsecond 10.6μm CO2 laser. The spectral shifts of the IR maxima were in opposite spectral directions for the two types of lasers. This one observed difference correlates well with spectral shift of their critical temperatures. The possible explanation is given by performance of DFT calculations of the charge density redistribution and the time kinetics of the photovoltaic response. To understand the kinetics of the photoinduced processes the time kinetics of photoresponse was done for the particular laser wavelengths.

  5. Study of Sn removal processes for in-situ collector cleaning

    NASA Astrophysics Data System (ADS)

    Elg, Daniel T.; Panici, Gianluca A.; Srivastava, Shailendra N.; Ruzic, D. N.

    2016-03-01

    An in-situ hydrogen plasma cleaning technique to clean Sn off of EUV collector optics is studied in detail. The cleaning process uses hydrogen radicals (formed in the hydrogen plasma) to interact with Sn-coated surfaces, forming SnH4 and being pumped away. This technique has been used to clean a 300mm-diameter stainless steel dummy collector optic, and EUV reflectivity of multilayer mirror samples was restored after cleaning Sn from them, validating the potential of this technology. This method has the potential to significantly reduce downtime and increase source availability. However, net Sn removal is limited by decomposition of the SnH4 molecule upon impact with the collector and the resulting redeposition of Sn. This is true in all cleaning systems that make use of hydrogen radicals. Thus, to guide the design of effective cleaning systems, the transport of Sn in the chamber, and the fundamental processes affecting it, must be understood. Accordingly, an investigation into these processes Sn removal is being performed. These processes include the advection of gas through the chamber, the creation of hydrogen radicals, the etching of Sn by radicals, and the surface decomposition of SnH4. In this paper, experiments to determine the radical density are presented, along with a theoretical plasma chemistry model that explains the processes behind radical creation and validates the radical density measurements. Additionally, experiments are shown that provide an insight into the etching of Sn by hydrogen radicals, yielding calculations of etching probability as well as showing that Sn etching is very sensitive to oxygen contamination and surface morphology.

  6. Doping and effect of nano-diamond and carbon-nanotubes on flux pinning properties of MgB 2

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Yang, Y.; Cheng, C. H.; Zhang, Y.

    2007-10-01

    Doping effects of two types of nano-carbons: nano-diamond and carbon-nanotubes (CNTs), on the flux pinning properties of MgB2 bulk materials have been studied. Compared with nano-diamond, CNTs is prone to be doped into MgB2 lattice. Nano-diamond doping improves Jc(H) characteristics more significantly than CNTs doping in MgB2. TEM analysis reveals a unique microstructure in diamond-doped MgB2, which consists of tightly packed MgB2 nanograins (50-100 nm) with dense distribution of diamond nanoparticles (10-20 nm) inside the grains. Relatively, such a unique microstructure is not easy to form in CNTs-doped MgB2 due to an active reaction between CNTs and MgB2.

  7. The influence of heating rate on superconducting characteristics of MgB2 obtained by spark plasma sintering technique

    NASA Astrophysics Data System (ADS)

    Aldica, G.; Burdusel, M.; Popa, S.; Enculescu, M.; Pasuk, I.; Badica, P.

    2015-12-01

    Superconducting bulks of MgB2 were obtained by the Spark Plasma Sintering (SPS) technique. Different heating rates of 20, 100, 235, 355, and 475 °C/min were used. Samples have high density, above 95%. The onset critical temperature Tc, is about 38.8 K. There is an optimum heating rate of ∼100 °C/min to maximize the critical current density Jc0, the irreversibility field Hirr, the product (Jc0 x μ0Hirr), and to partially avoid formation of undesirable flux jumps at low temperatures. Significant microstructure differences were revealed for samples processed with low and high heating rates in respect to grain boundaries.

  8. A 2-D Array of Superconducting Magnesium Diboride (MgB2) Far-IR Thermal Detectors for Planetary Exploration

    NASA Technical Reports Server (NTRS)

    Lakew, Brook

    2009-01-01

    A 2-D array of superconducting Magnesium Diboride(MgB2) far IR thermal detectors has been fabricated. Such an array is intended to be at the focal plane of future generation thermal imaging far-IR instruments that will investigate the outer planets and their icy moons. Fabrication and processing of the pixels of the array as well as noise characterization of architectured MgB2 thin films will be presented. Challenges and solutions for improving the performance of the array will be discussed.

  9. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing.

    PubMed

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Strittmatter, André; Rodt, Sven; Reitzenstein, Stephan

    2015-07-01

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices. PMID:26233395

  10. In situ observation and analysis of crystal growth process of GdBCO superconductive oxide

    NASA Astrophysics Data System (ADS)

    Nakahara, Y.; Inokawa, T.; Mori, N.; Ogi, K.

    2006-10-01

    To clarify the nucleation and growth process of 123 crystals, growth of faceted Gd123(GdBa2Cu3O7-δ) crystals was observed in situ on MgO(1 0 0) by using a high temperature optical microscope with zoom lens (×50-500). Gd123 crystals nucleated and grew at each undercooling (ΔT = 30, 35, 40, 45 K). Growth rate (u) and incubation time (tinc) for nucleation were obtained from the relationship between time and position of faceted interface. u was approximated by a function of ΔT: u =Agp ΔTr2 / η (T) , where Agp is a constant, Agp = 1.0 × 10-5. Nucleation rate (Iv) was obtained from the relationship between time and number of nucleated crystals. Iv was approximated by an exponential function: Iv = {An / η (T) } exp (- B / ΔTr2) , where An and B are constants, An = 1.3 × 107, B = 2.7 × 10-3. The nucleation and growth process of Gd123 crystals were expressed quantitatively by the above equations.

  11. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    PubMed

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil.

  12. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    SciTech Connect

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Rodt, Sven Reitzenstein, Stephan; Strittmatter, André

    2015-07-15

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  13. Advanced in-situ electron-beam lithography for deterministic nanophotonic device processing

    NASA Astrophysics Data System (ADS)

    Kaganskiy, Arsenty; Gschrey, Manuel; Schlehahn, Alexander; Schmidt, Ronny; Schulze, Jan-Hindrik; Heindel, Tobias; Strittmatter, André; Rodt, Sven; Reitzenstein, Stephan

    2015-07-01

    We report on an advanced in-situ electron-beam lithography technique based on high-resolution cathodoluminescence (CL) spectroscopy at low temperatures. The technique has been developed for the deterministic fabrication and quantitative evaluation of nanophotonic structures. It is of particular interest for the realization and optimization of non-classical light sources which require the pre-selection of single quantum dots (QDs) with very specific emission features. The two-step electron-beam lithography process comprises (a) the detailed optical study and selection of target QDs by means of CL-spectroscopy and (b) the precise retrieval of the locations and integration of target QDs into lithographically defined nanostructures. Our technology platform allows for a detailed pre-process determination of important optical and quantum optical properties of the QDs, such as the emission energies of excitonic complexes, the excitonic fine-structure splitting, the carrier dynamics, and the quantum nature of emission. In addition, it enables a direct and precise comparison of the optical properties of a single QD before and after integration which is very beneficial for the quantitative evaluation of cavity-enhanced quantum devices.

  14. Aquifer restoration at in-situ leach uranium mines: evidence for natural restoration processes

    SciTech Connect

    Deutsch, W.J.; Serne, R.J.; Bell, N.E.; Martin, W.J.

    1983-04-01

    Pacific Northwest Laboratory conducted experiments with aquifer sediments and leaching solution (lixiviant) from an in-situ leach uranium mine. The data from these laboratory experiments and information on the normal distribution of elements associated with roll-front uranium deposits provide evidence that natural processes can enhance restoration of aquifers affected by leach mining. Our experiments show that the concentration of uranium (U) in solution can decrease at least an order of magnitude (from 50 to less than 5 ppM U) due to reactions between the lixiviant and sediment, and that a uranium solid, possibly amorphous uranium dioxide, (UO/sub 2/), can limit the concentration of uranium in a solution in contact with reduced sediment. The concentrations of As, Se, and Mo in an oxidizing lixiviant should also decrease as a result of redox and precipitation reactions between the solution and sediment. The lixiviant concentrations of major anions (chloride and sulfate) other than carbonate were not affected by short-term (less than one week) contact with the aquifer sediments. This is also true of the total dissolved solids level of the solution. Consequently, we recommend that these solution parameters be used as indicators of an excursion of leaching solution from the leach field. Our experiments have shown that natural aquifer processes can affect the solution concentration of certain constituents. This effect should be considered when guidelines for aquifer restoration are established.

  15. In situ ellipsometry of surface layer of non-metallic transparent materials during its finish processing

    NASA Astrophysics Data System (ADS)

    Filatov, Oleksandr Y.; Poperenko, Leonid V.

    2006-10-01

    For modern technology applications it is important to develop non-contact methods of control of the modification of dielectric materials surface layer. The aim of the work is to determine the level of roughness changes in the surface layer of non-metallic material, optical glass BK-7, and to control it by in situ ellipsometry. The probing light spot was formed at a second (lower) reflective surface of the plate being studied during its mechanical processing at direct observation of these changes. The fine mechanical polishing was carried out for 2 hours by using the grinding-polishing machine installed directly on the sample table of ellipsometer LEF-3M. The angle of light incidence was close to 70 degree. The ellipsometric parameters, were determined within the mechanically processed area. For this purpose, the probing light beam passed two times through the sample and then returned to the initial (air) medium, where its polarization state was studied. The polarized beam falls on lower plate surface polished by conventional technology using grinding-polishing CeO 2-based instrument "Aquapol" (grain size 1 micron). The time dependences of the ellipsometric parameters during the surface layer treatment were studied. In these dependences the tendency of changes of ellipsometric parameters indicates the surface roughness enhancement.

  16. Monitoring biodegradation of diesel fuel in bioventing processes using in situ respiration rate.

    PubMed

    Lee, T H; Byun, I G; Kim, Y O; Hwang, I S; Park, T J

    2006-01-01

    An in situ measuring system of respiration rate was applied for monitoring biodegradation of diesel fuel in a bioventing process for bioremediation of diesel contaminated soil. Two laboratory-scale soil columns were packed with 5 kg of soil that was artificially contaminated by diesel fuel as final TPH (total petroleum hydrocarbon) concentration of 8,000 mg/kg soil. Nutrient was added to make a relative concentration of C:N:P = 100:10:1. One soil column was operated with continuous venting mode, and the other one with intermittent (6 h venting/6 h rest) venting mode. On-line O2 and CO2 gas measuring system was applied to measure O2 utilisation and CO2 production during biodegradation of diesel for 5 months. Biodegradation rate of TPH was calculated from respiration rate measured by the on-line gas measuring system. There were no apparent differences between calculated biodegradation rates from two columns with different venting modes. The variation of biodegradation rates corresponded well with trend of the remaining TPH concentrations comparing other biodegradation indicators, such as C17/pristane and C18/phytane ratio, dehydrogenase activity, and the ratio of hydrocarbon utilising bacteria to total heterotrophic bacteria. These results suggested that the on-line measuring system of respiration rate would be applied to monitoring biodegradation rate and to determine the potential applicability of bioventing process for bioremediation of oil contaminated soil. PMID:16722077

  17. Cyanobacteria to Link Closed Ecological Systems and In-Situ Resources Utilization Processes

    NASA Astrophysics Data System (ADS)

    Brown, Igor

    Introduction: A major goal for the Vision of Space Exploration is to extend human presence across the solar sys-tem. With current technology, however, all required consumables for these missions (propellant, air, food, water) as well as habitable volume and shielding to support human explorers will need to be brought from Earth. In-situ pro-duction of consumables (In-Situ Resource Utilization-ISRU) will significantly facilitate current plans for human ex-ploration and colonization of the solar system, especially by reducing the logistical overhead such as recurring launch mass. The production of oxygen from lunar materials is generally recognized as the highest priority process for lunar ISRU, for both human metabolic and fuel oxidation needs. The most challenging technology developments for future lunar settlements may lie in the extraction of elements (O, Fe, Mn, Ti, Si, etc) from local rocks and soils for life support, industrial feedstock and the production of propellants. With few exceptions (e.g., Johannson, 1992), nearly all technology development to date has employed an ap-proach based on inorganic chemistry (e.g. Allen et al., 1996). None of these technologies include concepts for inte-grating the ISRU system with a bioregenerative life support system and a food production systems. Bioregenerative life support efforts have recently been added to the Constellation ISRU development program (Sanders et al, 2007). Methods and Concerns: The European Micro-Ecological Life Support System Alternative (MELiSSA) is an ad-vanced concept for organizing a bioregenerative system for long term space flights and extraterrestrial settlements (Hendrickx, De Wever et al., 2005). However the MELiSSA system is a net consumer of ISRU products without a net return to in-situ technologies, e.g.. to extract elements as a result of complete closure of MELiSSA. On the other hand, the physical-chemical processes for ISRU are typically massive (relative to the rate of oxygen

  18. Sensor-model prediction, monitoring and in-situ control of liquid RTM advanced fiber architecture composite processing

    NASA Astrophysics Data System (ADS)

    Kranbuehl, D.; Kingsley, P.; Hart, S.; Loos, A.; Hasko, G.; Dexter, B.

    In-situ frequency dependent electromagnetic sensors (FDEMS) and the Loos resin transfer model have been used to select and control the processing properties of an epoxy resin during liquid pressure RTM impregnation and cure. Once correlated with viscosity and degree of cure the FDEMS sensor monitors and the RTM processing model predicts the reaction advancement of the resin, viscosity and the impregnation of the fabric. This provides a direct means for predicting, monitoring, and controlling the liquid RTM process in-situ in the mold throughout the fabrication process and the effects of time, temperature, vacuum and pressure. Most importantly, the FDEMS-sensor model system has been developed to make intelligent decisions, thereby automating the liquid RTM process and removing the need for operator direction.

  19. Sensor-model prediction, monitoring and in-situ control of liquid RTM advanced fiber architecture composite processing

    NASA Technical Reports Server (NTRS)

    Kranbuehl, D.; Kingsley, P.; Hart, S.; Loos, A.; Hasko, G.; Dexter, B.

    1992-01-01

    In-situ frequency dependent electromagnetic sensors (FDEMS) and the Loos resin transfer model have been used to select and control the processing properties of an epoxy resin during liquid pressure RTM impregnation and cure. Once correlated with viscosity and degree of cure the FDEMS sensor monitors and the RTM processing model predicts the reaction advancement of the resin, viscosity and the impregnation of the fabric. This provides a direct means for predicting, monitoring, and controlling the liquid RTM process in-situ in the mold throughout the fabrication process and the effects of time, temperature, vacuum and pressure. Most importantly, the FDEMS-sensor model system has been developed to make intelligent decisions, thereby automating the liquid RTM process and removing the need for operator direction.

  20. In situ characterization of uranium and americium oxide solid solution formation for CRMP process: first combination of in situ XRD and XANES measurements.

    PubMed

    Caisso, Marie; Picart, Sébastien; Belin, Renaud C; Lebreton, Florent; Martin, Philippe M; Dardenne, Kathy; Rothe, Jörg; Neuville, Daniel R; Delahaye, Thibaud; Ayral, André

    2015-04-14

    Transmutation of americium in heterogeneous mode through the use of U1-xAmxO2±δ ceramic pellets, also known as Americium Bearing Blankets (AmBB), has become a major research axis. Nevertheless, in order to consider future large-scale deployment, the processes involved in AmBB fabrication have to minimize fine particle dissemination, due to the presence of americium, which considerably increases the risk of contamination. New synthesis routes avoiding the use of pulverulent precursors are thus currently under development, such as the Calcined Resin Microsphere Pelletization (CRMP) process. It is based on the use of weak-acid resin (WAR) microspheres as precursors, loaded with actinide cations. After two specific calcinations under controlled atmospheres, resin microspheres are converted into oxide microspheres composed of a monophasic U1-xAmxO2±δ phase. Understanding the different mechanisms during thermal conversion, that lead to the release of organic matter and the formation of a solid solution, appear essential. By combining in situ techniques such as XRD and XAS, it has become possible to identify the key temperatures for oxide formation, and the corresponding oxidation states taken by uranium and americium during mineralization. This paper thus presents the first results on the mineralization of (U,Am) loaded resin microspheres into a solid solution, through in situ XAS analysis correlated with HT-XRD. PMID:25742991

  1. Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

    DOEpatents

    Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

    2016-03-01

    A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

  2. Thermodynamic stability of transition metals on the Mg-terminated MgB2 (0001) surface and their effects on hydrogen dissociation and diffusion

    NASA Astrophysics Data System (ADS)

    Wang, Yongli; Michel, Kyle; Zhang, Yongsheng; Wolverton, C.

    2015-04-01

    The hydrogenation of MgB2 is a critical step in the reversibility of several well-known hydrogen storage reactions. Of the many processes that must occur during rehydrogenation, at least two of them take place near the surface: the dissociation of H2 molecules and the subsequent diffusion of atomic hydrogen. Using first-principles calculations, we determine the energetic barriers for these processes on the ideal Mg-terminated MgB2 (0001) surface, as well as on surfaces containing transition metal dopants (Sc-Zn, Y-Cd, Pt, and Au). The calculated dissociation barrier for H2 on the clean surface is 0.89 eV, and the surface diffusion barrier is 0.17 eV. However, we find examples of dopants that significantly decrease the activation barrier for the dissociation of H2 . Our calculations suggest that Ni, Cu, and Pd are good catalytic candidates for the surface processes involved in MgB2 rehydrogenation.

  3. Potential ability of 3 T-class trapped field on MgB2 bulk surface synthesized by the infiltration-capsule method

    NASA Astrophysics Data System (ADS)

    Naito, Tomoyuki; Ogino, Arata; Fujishiro, Hiroyuki

    2016-11-01

    We successfully synthesized a dense (˜90%-filled) MgB2 bulk with no residual Mg via an infiltration process by overcoming the problems in this process such as the expansion of a B precursor disk under a liquid Mg infiltration and the residuals of unreacted Mg in the bulk using a specially designed capsule. As a result, we have achieved a record-high trapped field to date, {B}{{T}}, of 2.4 T at the center of the bulk surface at the lowest temperature of 15.9 K among the infiltration-processed MgB2 bulks. The trapped-fields simulated for a model with the experimental {J}{{c}}({μ }0H) characteristics well reproduced the experimental {B}{{T}}’s and gave a reliable estimated {B}{{T}} below 15.9 K. The extrapolation of the experimental and simulated {B}{{T}} curve reached 3 T at 4.2 K. The critical current densities, {J}{{c}}({μ }0H)’s, at 20 K were 1.8 × 105 A cm-2 under the self-field and 4.5 × 103 A cm-2 under the magnetic-field of {μ }0H = 3 T. The connectivity, K, of 16% of the present bulk was comparable with that of the ˜50%-filled MgB2 bulk. The high {B}{{T}} with low K and the microstructure of the present bulk suggested that the high- and low-{J}{{c}} regions coexisted because of the wide variation of the MgB2 grain-size.

  4. Superconductivity in MgB2: clean or dirty?

    PubMed

    Mazin, I I; Andersen, O K; Jepsen, O; Dolgov, O V; Kortus, J; Golubov, A A; Kuz'menko, A B; Van Der Marel, D

    2002-09-01

    A large number of experimental facts and theoretical arguments favor a two-gap model for superconductivity in MgB2. However, this model predicts strong suppression of the critical temperature by interband impurity scattering and, presumably, a strong correlation between the critical temperature and the residual resistivity. No such correlation has been observed. We argue that this fact can be understood if the band disparity of the electronic structure is taken into account, not only in the superconducting state, but also in normal transport.

  5. Two-band superconductivity in MgB2.

    PubMed

    Iavarone, M; Karapetrov, G; Koshelev, A E; Kwok, W K; Crabtree, G W; Hinks, D G; Kang, W N; Choi, Eun-Mi; Kim, Hyun Jung; Kim, Hyeong-Jin; Lee, S I

    2002-10-28

    The study of the anisotropic superconductor MgB2 using a combination of scanning tunneling microscopy and spectroscopy reveals two distinct energy gaps at Delta(1)=2.3 meV and Delta(2)=7.1 meV at 4.2 K. Different spectral weights of the partial superconducting density of states are a reflection of different tunneling directions in this multiband system. Temperature evolution of the tunneling spectra follows the BCS scenario [Phys. Rev. Lett. 3, 552 (1959)

  6. Phonon dispersion and lifetimes in MgB2.

    PubMed

    Shukla, Abhay; Calandra, Matteo; D'Astuto, Matteo; Lazzeri, Michele; Mauri, Francesco; Bellin, Christophe; Krisch, Michael; Karpinski, J; Kazakov, S M; Jun, J; Daghero, D; Parlinski, K

    2003-03-01

    We measure phonon dispersion and linewidth in a single crystal of MgB2 along the Gamma-A, Gamma-M, and A-L directions using inelastic x-ray scattering. We use density functional theory to compute the effect of both electron-phonon coupling and anharmonicity on the linewidth, obtaining excellent agreement with experiment. Anomalous broadening of the E(2g) phonon mode is found all along Gamma-A. The dominant contribution to the linewidth is always the electron-phonon coupling.

  7. Disorder in carbon-doped HPCVD MgB2 thin films

    NASA Astrophysics Data System (ADS)

    Zhu, Ye; Voyles, P. M.; Pogrebnyakov, A. V.; Xi, X. X.

    2007-03-01

    Carbon-doped MgB2 films prepared by hybrid physical-chemical vapor deposition have the highest Hc2 (˜70 T at 0 K for H parallel to ab plane) of all MgB2 materials. We have characterized the nanoscale structure and chemistry of one such film by TEM and STEM. The C concentration in the Mg(B1-xCx)2 grains from EELS is not dramatically higher than that of C-doped bulk MgB2, so doping does not explain the high Hc2. Instead, the doped film has a variety of forms of structural disorder at length scales down to 5 nm, which may be sufficient to explain the Hc2 of these films. These include MgB2 domains with a 30 degree rotation about the c-axis, small angle rotations about c-axis, and a small tilt of the c-axis. There are also amorphous, C-rich regions between some MgB2 domains. The amorphous phase comes from the oversupply of C during growth, which may also cause the other disorder by interrupting epitaxial film growth. This work is supported by the FRG on MgB2, NSF DMR-0514592.

  8. A 0.6 T/650 mm RT Bore Solid Nitrogen Cooled MgB2 Demonstration Coil for MRI—a Status Report

    PubMed Central

    Bascuñán, Juan; Lee, Haigunan; Bobrov, Emmanuel S.; Hahn, Seungyong; Iwasa, Yukikazu; Tomsic, Mike; Rindfleisch, Matt

    2014-01-01

    Aiming to demonstrate feasibility and practicality of a low cost superconducting MRI magnet system targeted for use in small hospitals, rural communities and underdeveloped countries, MIT-Francis Bitter Magnet Laboratory has developed a 0.6 T/650 mm room temperature bore demonstration coil wound with multifilament MgB2 conductor and cooled via an innovative cryogenic design/operation. The coil is to be maintained cold by solid nitrogen kept in the solid state by a cryocooler. In the event of a power failure the cryocooler is automatically thermally decoupled from the system. In this paper we present details of the MgB2 conductor, winding process, and preliminary theoretical analysis of the current-carrying performance of the conductively cooled coils in zero background field and over the 10–30 K temperature range. PMID:25580068

  9. A noval in situ study of adsorption processes at Au(111) electrodes by second harmonic generation

    NASA Astrophysics Data System (ADS)

    Pettinger, B.; Lipkowski, J.; Mirwald, S.; Friedrich, A.

    1992-05-01

    Second harmonic generation (SHG) is an in situ spectroscopic tool par excellence for an electrode surface. Since the SHG response is determined by the nonlinear susceptibility tensor of third rank, χ(2), an understanding of the quite complex and different SHG-anisotropy patterns requires the evaluation of the important χijk tensor elements and their distinct dependences on both electrode potential and adsorption of ions or neutral molecules. The Fourier analysis of the azimuthal SHG data reveals that the observed SHG potential dependences arise mainly from two distinct sources: (i) The surface reconstruction, here denoted as Au(111)-(1 × 23) ↔ Au(111)-(1 × 1); it is controlled by potential and ad/desorption of ions or molecules and leads, via the SHG anisotropy, to an observable change in surface symmetry such as C3v ↔ Cs. (ii) The change of charge density of the electrode surface which is caused by potential shifts and/or adsorption processes; it alters mainly the ax term, e.g. the perpendicular part of the nonlinear polarizability of the metal surface.

  10. In situ process diagnostics of silane plasma for device-quality a-Si:H deposition

    NASA Astrophysics Data System (ADS)

    Shing, Y. H.; Perry, J. W.; Hermann, A. M.

    Coherent anti-Stokes Raman spectroscopy (CARS) and mass spectrometry (MS) have been applied to in situ process diagnostics of a silane plasma for device-quality a-Si:H film deposition. Silane depletion was directly measured by CARS and is linearly dependent on RF power in the region of 4-12 W with a slope of 0.5 percent/mW-sq cm. The depletion is also dependent on SiH4 flow rate starting with a 50 percent depletion at a low flow rate of 5.6 sccm and asymptotically approaching an 8 percent depletion at a flow rate of 80 sccm. The mass spectral line signal intensity of disilane increases with RF power and shows an apparent transition at 6 W. Disilane formation in silane plasma, film deposition rate, and silane depletion ratio as a function of the RF power indicate that the film growth mechanism in the low-power region of 3.5-6.5 W is substantially different from that in the high-power region of 6.5-12 W.

  11. In situ monitoring of the hydration process of K-PS geopolymer cement with ESEM

    SciTech Connect

    Sun Wei; Zhang Yunsheng; Lin Wei; Liu Zhiyong

    2004-06-01

    Environmental scanning electron microscope (ESEM) was used to in situ quantitatively study the hydration process of K-PS geopolymer cement under an 80% RH environment. An energy dispersion X-ray analysis (EDXA) was also employed to distinguish the chemical composition of hydration product. The ESEM micrographs showed that metakaolin particles pack loosely at 10 min after mixing, resulting in the existence of many large voids. As hydration proceeds, a lot of gels were seen and gradually precipitated on the surfaces of these particles. At later stage, these particles were wrapped by thick gel layers and their interspaces were almost completely filled. The corresponding EDXA results illustrated that the molar ratios of K/Al increase while Si/Al decrease with the development of hydration. As a result, the molar ratios of K/Al and Si/Al of hydration products at an age of 4 h amounted to 0.99 and 1.49, respectively, which were close to the theoretical values (K/Al=1.0, Si/Al=1.0 for K-PS geopolymer cement paste). In addition, well-developed crystals could not been found at any ages; instead, spongelike amorphous gels were always been observed.

  12. In situ observation and analysis of faceted crystal growth process in REBCO superconductive oxide

    NASA Astrophysics Data System (ADS)

    Mori, N.; Nakahara, Y.; Ogi, K.; Mukaida, M.

    2007-10-01

    To clarify the nucleation and growth process of 123 crystals, growth of faceted RE123 (REBa2Cu3O7-X, RE = Nd, Sm, Gd, Y) crystals was observed in situ on MgO(1 0 0) by using high temperature optical microscope with zoom lens. RE123 crystals nucleated and grew at each undercooling (ΔT = 13-50 K). Growth rate (u) and incubation time (tinc) for nucleation were obtained from the relationship between the position of faceted interface and time (t). u increased with increasing ΔTr2 , where ΔTr = ΔT/Tp, Tp was peritectic temperature. Nucleation rate (Iv) was obtained from the relationship between the number of nucleated crystals (n) and time. Iv increased with increasing of exp (- B / ΔTr2), where B was a constant. Both u and Iv under a fixed ΔT increased with increasing Tp: u(Nd123) > u(Sm123) > u(Gd123) and Iv(Nd123) > Iv(Sm123) > Iv(Gd123) for Tp(Nd123) > Tp(Sm123) > Tp(Gd123) in Ar-1%O2 atmosphere.

  13. System for producing a uniform rubble bed for in situ processes

    DOEpatents

    Galloway, Terry R.

    1983-01-01

    A method and a cutter for producing a large cavity filled with a uniform bed of rubblized oil shale or other material, for in situ processing. A raise drill head (72) has a hollow body (76) with a generally circular base and sloping upper surface. A hollow shaft (74) extends from the hollow body (76). Cutter teeth (78) are mounted on the upper surface of the body (76) and relatively small holes (77) are formed in the body (76) between the cutter teeth (78). Relatively large peripheral flutes (80) around the body (76) allow material to drop below the drill head (72). A pilot hole is drilled into the oil shale deposit. The pilot hole is reamed into a large diameter hole by means of a large diameter raise drill head or cutter to produce a cavity filled with rubble. A flushing fluid, such as air, is circulated through the pilot hole during the reaming operation to remove fines through the raise drill, thereby removing sufficient material to create sufficient void space, and allowing the larger particles to fill the cavity and provide a uniform bed of rubblized oil shale.

  14. System for producing a uniform rubble bed for in situ processes

    DOEpatents

    Galloway, T.R.

    1983-07-05

    A method and a cutter are disclosed for producing a large cavity filled with a uniform bed of rubblized oil shale or other material, for in situ processing. A raise drill head has a hollow body with a generally circular base and sloping upper surface. A hollow shaft extends from the hollow body. Cutter teeth are mounted on the upper surface of the body and relatively small holes are formed in the body between the cutter teeth. Relatively large peripheral flutes around the body allow material to drop below the drill head. A pilot hole is drilled into the oil shale deposit. The pilot hole is reamed into a large diameter hole by means of a large diameter raise drill head or cutter to produce a cavity filled with rubble. A flushing fluid, such as air, is circulated through the pilot hole during the reaming operation to remove fines through the raise drill, thereby removing sufficient material to create sufficient void space, and allowing the larger particles to fill the cavity and provide a uniform bed of rubblized oil shale. 4 figs.

  15. In situ process diagnostics of silane plasma for device-quality a-Si:H deposition

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Perry, J. W.; Hermann, A. M.

    1987-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) and mass spectrometry (MS) have been applied to in situ process diagnostics of a silane plasma for device-quality a-Si:H film deposition. Silane depletion was directly measured by CARS and is linearly dependent on RF power in the region of 4-12 W with a slope of 0.5 percent/mW-sq cm. The depletion is also dependent on SiH4 flow rate starting with a 50 percent depletion at a low flow rate of 5.6 sccm and asymptotically approaching an 8 percent depletion at a flow rate of 80 sccm. The mass spectral line signal intensity of disilane increases with RF power and shows an apparent transition at 6 W. Disilane formation in silane plasma, film deposition rate, and silane depletion ratio as a function of the RF power indicate that the film growth mechanism in the low-power region of 3.5-6.5 W is substantially different from that in the high-power region of 6.5-12 W.

  16. In situ gasification process for producing product gas enriched in carbon monoxide and hydrogen

    DOEpatents

    Capp, John P.; Bissett, Larry A.

    1978-01-01

    The present invention is directed to an in situ coal gasification process wherein the combustion zone within the underground coal bed is fed with air at increasing pressure to increase pressure and temperature in the combustion zone for forcing product gases and water naturally present in the coal bed into the coal bed surrounding the combustion zone. No outflow of combustion products occurs during the build-up of pressure and temperature in the combustion zone. After the coal bed reaches a temperature of about 2000.degree. F and a pressure in the range of about 100-200 psi above pore pressure the airflow is terminated and the outflow of the combustion products from the combustion zone is initiated. The CO.sub.2 containing gaseous products and the water bleed back into the combustion zone to react endothermically with the hot carbon of the combustion zone to produce a burnable gas with a relatively high hydrogen and carbon monoxide content. About 11 to 29 percent of the gas recovered from the combustion zone is carbon monoxide which is considerably better than the 4 to 10 percent carbon monoxide obtained by employing previously known coal gasification techniques.

  17. The role of starch doping on the superconducting properties of MgB2

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Moharana, S. S.; Dey, T. K.

    2014-09-01

    The effect of different amount of starch addition on structural and superconducting properties of superconducting MgB2 has been discussed. The samples are synthesized by conventional solid reaction method. XRD analysis confirms that carbon, which is produced during synthesis due to decomposition of starch, is substituted in the B sites. High resolution transmission electron microscope (HRTEM) picture infers the presence of large number of nanosized precipitates (size ∼10-20 nm) in starch doped MgB2 pellets. Superconducting transition temperature (Tc0) of MgB2 (∼38 K) decreases due to the addition of starch. The critical current density (Jc) of starch added MgB2 samples, however, shows significant improvement in whole field range, especially at high magnetic fields. MgB2 added with 2 wt.% of starch gives the best performance amongst the investigated samples and at 20 K displays ∼42 times enhancement in Jc under 4 T field compared to that for pure MgB2. The field dependence of the critical current density (Jc) of starch added MgB2 is explained fairly well in terms of collective pinning theory. An excellent scaling of the reduced critical current density, Jn(=Jc/Jc(0)) and the reduced field hn (=H/H0) is observed for both pure and starch added MgB2 polycrystalline pellets at different temperatures, where Jc(0) and H0 are the fitting parameters obtained from collective pinning model. However, the normalized pinning force density (FP/Fp(max)) of starch added samples does not display any scaling, but shows an excellent correspondence with modified Dew-Hughes expression. The presence of anisotropy and grain orientation is thought to be responsible for the absence of scaling of normalized pinning force density in starch added MgB2 pellets.

  18. Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

    SciTech Connect

    Hu, Jian Zhi; Sears, Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H. F.

    2015-11-24

    A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

  19. In situ Scanning Electron Microscopy of Silicon Anode Reactions in Lithium-Ion Batteries during Charge/Discharge Processes

    PubMed Central

    Chen, Chih-Yao; Sano, Teruki; Tsuda, Tetsuya; Ui, Koichi; Oshima, Yoshifumi; Yamagata, Masaki; Ishikawa, Masashi; Haruta, Masakazu; Doi, Takayuki; Inaba, Minoru; Kuwabata, Susumu

    2016-01-01

    A comprehensive understanding of the charge/discharge behaviour of high-capacity anode active materials, e.g., Si and Li, is essential for the design and development of next-generation high-performance Li-based batteries. Here, we demonstrate the in situ scanning electron microscopy (in situ SEM) of Si anodes in a configuration analogous to actual lithium-ion batteries (LIBs) with an ionic liquid (IL) that is expected to be a functional LIB electrolyte in the future. We discovered that variations in the morphology of Si active materials during charge/discharge processes is strongly dependent on their size and shape. Even the diffusion of atomic Li into Si materials can be visualized using a back-scattering electron imaging technique. The electrode reactions were successfully recorded as video clips. This in situ SEM technique can simultaneously provide useful data on, for example, morphological variations and elemental distributions, as well as electrochemical data. PMID:27782200

  20. Enhanced arsenic removal by in situ formed Fe-Mn binary oxide in the aeration-direct filtration process.

    PubMed

    Wu, Kun; Liu, Rui-Ping; Liu, Hui-Juan; Lan, Hua-Chun; Qu, Jiu-Hui

    2012-11-15

    Field studies were conducted to evaluate the feasibility of an in situ formed Fe-Mn binary oxide (in situ FMBO) for improving arsenic (As) removal in the aeration-direct filtration process. The transformation and transportation of As, Fe, and Mn in the filter bed were also investigated. The in situ FMBO increased the As removal efficiency by 20-50% to keep the residual As below 10 μg/L. The optimum FMBO dosage was determined to be 0.55 mg/L with the Fe/Mn ratio as 10:1. The removal of Fe, Mn, turbidity, and particles was also improved to a large extent. The in situ FMBO favored the transformation of soluble As, Fe, and Mn into the solid phases, benefiting the removal of these pollutants by the subsequent filtration. Moreover, the deposited precipitates onto the filter media were characterized, as indicated by the analyses of SEM/EDS and particle size distribution. The long-term experiments exhibited decreased head loss growth and prolonged run length, suggesting an enhanced pollutant catching capacity of the filter media. The full-scale field study with a flow of 10,000 m3/d confirmed positive effects of in situ FMBO on As removal, with the average effluent As concentration reduced from 20 μg/L to 6 μg/L (reagent cost=0.006 ¥/m3). PMID:23017236

  1. Enhanced arsenic removal by in situ formed Fe-Mn binary oxide in the aeration-direct filtration process.

    PubMed

    Wu, Kun; Liu, Rui-Ping; Liu, Hui-Juan; Lan, Hua-Chun; Qu, Jiu-Hui

    2012-11-15

    Field studies were conducted to evaluate the feasibility of an in situ formed Fe-Mn binary oxide (in situ FMBO) for improving arsenic (As) removal in the aeration-direct filtration process. The transformation and transportation of As, Fe, and Mn in the filter bed were also investigated. The in situ FMBO increased the As removal efficiency by 20-50% to keep the residual As below 10 μg/L. The optimum FMBO dosage was determined to be 0.55 mg/L with the Fe/Mn ratio as 10:1. The removal of Fe, Mn, turbidity, and particles was also improved to a large extent. The in situ FMBO favored the transformation of soluble As, Fe, and Mn into the solid phases, benefiting the removal of these pollutants by the subsequent filtration. Moreover, the deposited precipitates onto the filter media were characterized, as indicated by the analyses of SEM/EDS and particle size distribution. The long-term experiments exhibited decreased head loss growth and prolonged run length, suggesting an enhanced pollutant catching capacity of the filter media. The full-scale field study with a flow of 10,000 m3/d confirmed positive effects of in situ FMBO on As removal, with the average effluent As concentration reduced from 20 μg/L to 6 μg/L (reagent cost=0.006 ¥/m3).

  2. In situ studies on controlling an atomically-accurate formation process of gold nanoclusters

    NASA Astrophysics Data System (ADS)

    Yang, Lina; Cheng, Hao; Jiang, Yong; Huang, Ting; Bao, Jie; Sun, Zhihu; Jiang, Zheng; Ma, Jingyuan; Sun, Fanfei; Liu, Qinghua; Yao, Tao; Deng, Huijuan; Wang, Shuxin; Zhu, Manzhou; Wei, Shiqiang

    2015-08-01

    Knowledge of the molecular formation mechanism of metal nanoclusters is essential for developing chemistry for accurate control over their synthesis. Herein, the ``top-down'' synthetic process of monodisperse Au13 nanoclusters via HCl etching of polydisperse Aun clusters (15 <= n <= 65) is traced by a combination of in situ X-ray/UV-vis absorption spectroscopy and time-dependent mass spectrometry. It is revealed experimentally that the HCl-induced synthesis of Au13 is achieved by accurately controlling the etching process with two distinctive steps, in sharp contrast to the traditional thiol-etching mechanism through release of the Au(i) complex. The first step involves the direct fragmentation of the initial larger Aun clusters into metastable intermediate Au8-Au13 smaller clusters. This is a critical step, which allows for the secondary size-growth step of the intermediates toward the atomically monodisperse Au13 clusters via incorporating the reactive Au(i)-Cl species in the solution. Such a secondary-growth pathway is further confirmed by the successful growth of Au13 through reaction of isolated Au11 clusters with AuClPPh3 in the HCl environment. This work addresses the importance of reaction intermediates in guiding the way towards controllable synthesis of metal nanoclusters.Knowledge of the molecular formation mechanism of metal nanoclusters is essential for developing chemistry for accurate control over their synthesis. Herein, the ``top-down'' synthetic process of monodisperse Au13 nanoclusters via HCl etching of polydisperse Aun clusters (15 <= n <= 65) is traced by a combination of in situ X-ray/UV-vis absorption spectroscopy and time-dependent mass spectrometry. It is revealed experimentally that the HCl-induced synthesis of Au13 is achieved by accurately controlling the etching process with two distinctive steps, in sharp contrast to the traditional thiol-etching mechanism through release of the Au(i) complex. The first step involves the direct

  3. Cyanobacteria to Link Closed Ecological Systems and In-Situ Resources Utilization Processes

    NASA Astrophysics Data System (ADS)

    Brown, Igor

    Introduction: A major goal for the Vision of Space Exploration is to extend human presence across the solar sys-tem. With current technology, however, all required consumables for these missions (propellant, air, food, water) as well as habitable volume and shielding to support human explorers will need to be brought from Earth. In-situ pro-duction of consumables (In-Situ Resource Utilization-ISRU) will significantly facilitate current plans for human ex-ploration and colonization of the solar system, especially by reducing the logistical overhead such as recurring launch mass. The production of oxygen from lunar materials is generally recognized as the highest priority process for lunar ISRU, for both human metabolic and fuel oxidation needs. The most challenging technology developments for future lunar settlements may lie in the extraction of elements (O, Fe, Mn, Ti, Si, etc) from local rocks and soils for life support, industrial feedstock and the production of propellants. With few exceptions (e.g., Johannson, 1992), nearly all technology development to date has employed an ap-proach based on inorganic chemistry (e.g. Allen et al., 1996). None of these technologies include concepts for inte-grating the ISRU system with a bioregenerative life support system and a food production systems. Bioregenerative life support efforts have recently been added to the Constellation ISRU development program (Sanders et al, 2007). Methods and Concerns: The European Micro-Ecological Life Support System Alternative (MELiSSA) is an ad-vanced concept for organizing a bioregenerative system for long term space flights and extraterrestrial settlements (Hendrickx, De Wever et al., 2005). However the MELiSSA system is a net consumer of ISRU products without a net return to in-situ technologies, e.g.. to extract elements as a result of complete closure of MELiSSA. On the other hand, the physical-chemical processes for ISRU are typically massive (relative to the rate of oxygen

  4. Improved critical current density of MgB2--carbon nanotubes composite.

    PubMed

    Shekhar, Chandra; Giri, Rajiv; Malik, S K; Srivastav, O N

    2007-06-01

    In the present study, we report a systematic study of doping/admixing of carbon nanotubes (CNTs) in different concentrations in MgB2. The composite material corresponding to MgB2-x at.% CNTs (35 at.% > or = x > or = 0 at.%) have been prepared by solid-state reaction at ambient pressure. All the samples in the present investigation have been subjected to structural/microstructural characterization employing XRD, Scanning electron microscopic (SEM), and Transmission electron microscopic (TEM) techniques. The magnetization measurements were performed by Physical property measurement system (PPMS) and electrical transport measurements have been done by the four-probe technique. The microstructural investigations reveal the formation of MgB2-carbon nanotube composites. A CNT connecting the MgB2 grains may enhance critical current density due to its size (approximately 5-20 nm diameter) compatible with coherence length of MgB2 (approximately 5-6 nm) and ballistic transport current carrying capability along the tube axis. The transport critical current density (Jct) of MgB2 samples with varying CNTs concentration have been found to vary significantly e.g., Jct of the MgB2 sample with 10 at.% CNT addition is approximately 2.3 x 10(3) A/cm2 and its value for MgB2 sample without CNT addition is approximately 7.2 x 102 A/cm2 at 20 K. In order to study the flux pinning effect of CNTs doping/ admixing in MgB2, the evaluation of intragrain critical current density (JJ) has been carried out through magnetic measurements on the fine powdered version of the as synthesized samples. The optimum result on Jc is obtained for 10 at.% CNTs admixed MgB2 sample at 5 K, the Jc reaches approximately 5.2 x 10(6) A/cm2 in self field, -1.6 x 10(6) A/cm2 at 1 T, approximately 2.9 x 10(5) A/cm2 at 2.6 T, and approximately 3.9 x 10(4) A/cm2 at 4 T. The high value of intragrain Jc in 10 at.% CNTs admixed MgB2 superconductor has been attributed to the incorporation of CNTs into the crystal matrix of

  5. Doping Effect of Nano-Ybco Additive on MgB2

    NASA Astrophysics Data System (ADS)

    Rui, X. F.; Sun, X. F.; Xu, X. L.; Zhang, L.; Zhang, H.

    The effect of YBCO nanoparticles added into MgB2 on Tc, Jc, and flux pinning was studied for MgB2(YBCO)x with x=0, 5, 10, 15 wt%. Phase analysis shows that none of elements are doped into the MgB2 lattice in the samples with YBCO addition. For the samples with YBCO addition, the Jc-H characteristics behave poorly in comparison with the pure sample. Our experimental results show that the nanoscale size of addition dosen't comprise the only condition for its effectiveness as pinning centers.

  6. Terahertz surface impedance of epitaxial MgB2 thin film

    NASA Astrophysics Data System (ADS)

    Jin, B. B.; Kuzel, P.; Kadlec, F.; Dahm, T.; Redwing, J. M.; Pogrebnyakov, A. V.; Xi, X. X.; Klein, N.

    2005-08-01

    We report on terahertz (THz) surface impedance measurement of an epitaxial MgB2 thin film using time domain THz spectroscopy. We show that the surface resistance of the MgB2 film is much lower than that of YBa2Cu3O7-δ and copper in the THz range. A linear dependence of the surface reactance on frequency is observed, yielding a penetration depth of about 100nm at low temperatures. The measurements agree qualitatively with calculations based on impurity scattering in the Born limit. Our results clearly indicate that MgB2 thin films have a great potential for THz electronic applications.

  7. Quantification of the resist dissolution process: an in situ analysis using high speed atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Santillan, Julius Joseph; Shichiri, Motoharu; Itani, Toshiro

    2016-03-01

    This work focuses on the application of a high speed atomic force microscope (HS-AFM) for the in situ visualization / quantification of the resist dissolution process. This technique, as reported in the past, has provided useful pointers on the formation of resist patterns during dissolution. This paper discusses about an investigation made on the quantification of what we refer to as "dissolution unit size" or the basic units of patterning material dissolution. This was done through the establishment of an originally developed analysis method which extracts the difference between two succeeding temporal states of the material film surface (images) to indicate the amount of change occurring in the material film at a specific span of time. Preliminary experiments with actual patterning materials were done using a positive-tone EUV model resist composed only of polyhydroxystyrene (PHS)-based polymer with a molecular weight of 2,500 and a polydispersity index of 1.2. In the absence of a protecting group, the material was utilized at a 50nm film thickness with post application bake of 90°C/60s. The resulting film is soluble in the alkali-based developer even without exposure. Results have shown that the dissolution components (dissolution unit size) of the PHS-based material are not of fixed size. Instead, it was found that aside from one constantly dissolving unit size, another, much larger dissolution unit size trend also occurs during material dissolution. The presence of this larger dissolution unit size suggests an occurrence of "polymer clustering". Such polymer clustering was not significantly present during the initial stages of dissolution (near the original film surface) but becomes more persistently obvious after the dissolution process reaches a certain film thickness below the initial surface.

  8. In-Situ Statistical Analysis of Autotune Simulation Data using Graphical Processing Units

    SciTech Connect

    Ranjan, Niloo; Sanyal, Jibonananda; New, Joshua Ryan

    2013-08-01

    Developing accurate building energy simulation models to assist energy efficiency at speed and scale is one of the research goals of the Whole-Building and Community Integration group, which is a part of Building Technologies Research and Integration Center (BTRIC) at Oak Ridge National Laboratory (ORNL). The aim of the Autotune project is to speed up the automated calibration of building energy models to match measured utility or sensor data. The workflow of this project takes input parameters and runs EnergyPlus simulations on Oak Ridge Leadership Computing Facility s (OLCF) computing resources such as Titan, the world s second fastest supercomputer. Multiple simulations run in parallel on nodes having 16 processors each and a Graphics Processing Unit (GPU). Each node produces a 5.7 GB output file comprising 256 files from 64 simulations. Four types of output data covering monthly, daily, hourly, and 15-minute time steps for each annual simulation is produced. A total of 270TB+ of data has been produced. In this project, the simulation data is statistically analyzed in-situ using GPUs while annual simulations are being computed on the traditional processors. Titan, with its recent addition of 18,688 Compute Unified Device Architecture (CUDA) capable NVIDIA GPUs, has greatly extended its capability for massively parallel data processing. CUDA is used along with C/MPI to calculate statistical metrics such as sum, mean, variance, and standard deviation leveraging GPU acceleration. The workflow developed in this project produces statistical summaries of the data which reduces by multiple orders of magnitude the time and amount of data that needs to be stored. These statistical capabilities are anticipated to be useful for sensitivity analysis of EnergyPlus simulations.

  9. In-situ NMR study of molecular and ionic processes inside carbon nanopores

    NASA Astrophysics Data System (ADS)

    Luo, Zhixiang

    Interactions of simple ions with water and interfaces play critical roles in many electrochemical and biological processes. They are especially significant in nanoconfined regions and have a profound impact in many applications, for instance nanofluidics and supercapacitors. This dissertation employs a nuclear magnetic resonance (NMR) technique to study their influence on the ionic processes inside carbon nanopores. To characterize the carbon micropore structure, a convenient NMR method is established by taking a 1H magic angle spinning (MAS) spectrum of the adsorbed water. A density functional theory (DFT) computation of the nucleus-independent chemical shift (NICS) yields a quantitative relationship between the NICS values and the micropore sizes. The carbon micropore size and distribution are derived from the chemical shift and the spectrum lineshape. For aqueous electrolytes inside uncharged carbon nanopores, the measurement of ion concentrations reveals a substantial electroneutrality breakdown. The specific ion effects and ion-ion correlations are shown to play crucial roles in determining the degree of electroneutrality breakdown. The importance of those interactions is further revealed by the asymmetric and nonlinear responses of ion concentrations to the charging of the confining carbon walls. Such information is obtained with a carbon supercapacitor built into the NMR probe. The NMR observations are validated by a numerical calculation of the ion distribution in the nanopores using the generalized Poisson-Boltzmann (PB) equation, demonstrating that the nonelectrostatic interfacial interactions can indeed dominate the electrostatic interactions and lead to the breakdown of electroneutrality inside nanoconfined regions. Interfacial ion hydration is an essential part of the specific ion effects. Using in-situ 23Na and 19F NMR on carbon supercapacitors with different carbon pore sizes, I provide a molecular-scale understanding of the permeation and

  10. Vortex-flux anomalies in MgB 2 polycrystals

    NASA Astrophysics Data System (ADS)

    Goeckner, H. P.; Claus, H.; Kouvel, J. S.

    2005-02-01

    For two MgB 2 polycrystalline samples prepared differently, magnetic hysteresis loops at 4.2 K revealed some striking magnetization ( M) anomalies at low magnetic fields ( H). In one sample, M drops abruptly by an amount that diminishes to zero as the maximum M, reached just before the drop, is reduced below a critical value (by reducing the slowly cycled H). The remanent magnetization ( Mrem), measured as the temperature ( T) was slowly raised from 4.2 K to Tc (39 K), was seen to decrease very rapidly just above 4.2 K and then remain constant up to ∼20 K, where it starts to descend gradually to zero at Tc. A similar set of anomalies was observed with the second sample, but where the hysteretic drop of M is rapid but not abrupt. However, both samples showed that the vortex-flux component of M remains nearly constant over a range of H just before the rapid drop of M, indicating that the vortices in the sample stay fairly constant in number before many of them exit the sample rapidly. For both MgB 2 samples, this whole set of anomalous properties disappears at temperatures above 5 K, where the slow steady descent of Mrem as T increases to Tc indicates that the size distribution of vortex pinning forces extends up to very high values.

  11. Characterization of MgB2 Superconducting Hot Electron Bolometers

    NASA Technical Reports Server (NTRS)

    Cunnane, D.; Kawamura, J. H.; Wolak, M. A.; Acharya, N.; Tan, T.; Xi, X. X.; Karasik, B. S.

    2014-01-01

    Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at the Terahertz frequencies. However, the current state of the art NbN mixers suffer from a small intermediate frequency (IF) bandwidth as well as a low operating temperature. MgB2 is a promising material for HEB mixer technology in view of its high critical temperature and fast thermal relaxation allowing for a large IF bandwidth. In this work, we have fabricated and characterized thin-film (approximately 15 nanometers) MgB2-based spiral antenna-coupled HEB mixers on SiC substrate. We achieved the IF bandwidth greater than 8 gigahertz at 25 degrees Kelvin and the device noise temperature less than 4000 degrees Kelvin at 9 degrees Kelvin using a 600 gigahertz source. Using temperature dependencies of the radiation power dissipated in the device we have identified the optical loss in the integrated microantenna responsible as a cause of the limited sensitivity of the current mixer devices. From the analysis of the current-voltage (IV) characteristics, we have derived the effective thermal conductance of the mixer device and estimated the required local oscillator power in an optimized device to be approximately 1 microwatts.

  12. Low-noise THz MgB2 Josephson mixer

    NASA Astrophysics Data System (ADS)

    Cunnane, Daniel; Kawamura, Jonathan H.; Acharya, Narendra; Wolak, Matthäus A.; Xi, X. X.; Karasik, Boris S.

    2016-09-01

    The potential applications for high frequency operation of the Josephson effect in MgB2 include THz mixers, direct detectors, and digital circuits. Here we report on MgB2 weak links which exhibit the Josephson behavior up to almost 2 THz and using them for low-noise heterodyne detection of THz radiation. The devices are made from epitaxial film grown in the c-axis direction by the hybrid physical-chemical vapor deposition method. The current in the junctions travels parallel to the surface of the film, thus making possible a large contribution of the quasi-two-dimensional σ-gap in transport across the weak link. These devices are connected to a planar spiral antenna with a dielectric substrate lens to facilitate coupling to free-space radiation for use as a detector. The IcRn product of the junction is 5.25 mV, giving confirmation of a large gap parameter. The sensitivity of the mixer was measured from 0.6 THz to 1.9 THz. At a bath temperature of over 20 K, a mixer noise temperature less than 2000 K (DSB) was measured near 0.6 THz.

  13. Electrochemical Processes for In-Situ Treatment of Contaminated Soils - Final Report - 09/15/1996 - 01/31/2001

    SciTech Connect

    Huang, Chin-Pao

    2001-05-31

    This project will study electrochemical processes for the in situ treatment of soils contaminated by mixed wastes, i.e., organic and inorganic. Soil samples collected form selected DOE waste sites will be characterized for specific organic and metal contaminants and hydraulic permeability. The soil samples are then subject to desorption experiments under various physical-chemical conditions such as pH and the presence of surfactants. Batch electro-osmosis experiments will be conducted to study the transport of contaminants in the soil-water systems. Organic contaminants that are released from the soil substrate will be treated by an advanced oxidation process, i.e., electron-Fantan. Finally, laboratory reactor integrating the elector-osmosis and elector-Fantan processes will be used to study the treatment of contaminated soil in situ.

  14. Magnetic field dependent stability and quench behavior and degradation limits in conduction-cooled MgB2 wires and coils

    PubMed Central

    Ye, Liyang; Cruciani, Davide; Xu, Minfeng; Mine, Susumu; Amm, Kathleen; Schwartz, Justin

    2015-01-01

    Long lengths of metal/MgB2 composite conductors with high critical current density (Jc), fabricated by the power-in-tube (PIT) process, have recently become commercially available. Owing to its electromagnetic performance in the 20 K – 30 K range and relatively low cost, MgB2 may be attractive for a variety of applications. One of the key issues for magnet design is stability and quench protection, so the behavior of MgB2 wires and magnets must be understood before large systems can emerge. In this work, the stability and quench behavior of several conduction-cooled MgB2 wires are studied. Measurements of the minimum quench energy and normal zone propagation velocity are performed on short samples in a background magnetic field up to 3 T and on coils in self-field and the results are explained in terms of variations in the conductor architecture, electrical transport behavior, operating conditions (transport current and background magnetic field) and experimental setup (short sample vs small coil). Furthermore, one coil is quenched repeatedly with increasing hot-spot temperature until Jc is decreased. It is found that degradation during quenching correlates directly with temperature and not with peak voltage; a safe operating temperature limit of 260 K at the surface is identified. PMID:25883414

  15. Epitaxial growth of MgB2 films at ambient temperature

    NASA Astrophysics Data System (ADS)

    Shishido, Hiroaki; Yoshida, Takuya; Nakagami, Takatoshi; Ishida, Takekazu

    We grew crystalline MgB2 thin films using molecular beam epitaxy at a low substrate temperature of 110 °C under an ultrahigh vacuum of about 10-6 Pa. MgB2 thin films were deposited on the (001) surface of a 4H-SiC substrate with an epitaxial Mg buffer layer. The epitaxial growth was confirmed by X-ray diffraction measurements. MgB2 thin films show a sharp superconducting transition at 27.2 K, with a relatively narrow superconducting transition width ΔTc = 0.9 K. The growth temperature was lower than any in prior reports on superconducting MgB2 thin films. The presence of the epitaxial Mg buffer layer is crucial for reducing the epitaxial temperature.

  16. Crystallization behavior of MgB2 films fabricated on copper cathodes via electrochemical technique

    NASA Astrophysics Data System (ADS)

    Yang, Huazhe; Sun, Xiaguang; Yu, Xiaoming; Qi, Yang

    2012-11-01

    An electrochemical technique was devised and settled to prepare MgB2 films on copper cathodes in MgCl2-Mg(BO2)2-NaCl-KCl molten salts. X-ray diffraction and scanning probe microscopy were adopted to investigate the phase composition and elements distribution of sample. R-T curve of film was monitored through standard four-probe method. Transmission electron microscope and scanning electron microscope analysis were chosen to investigate the crystallization behavior and morphology of the films at different electrolytic temperatures. The results indicated that MgB2 films were successfully fabricated on the copper cathodes, and the optimal electrolytic temperature was 601 °C. It was presumed that the non-conducting MgO impurities hindered continuous growth of MgB2 grain, which may result in dendritic growth of MgB2 grain.

  17. Tunnel junctions on as-grown MgB 2 films

    NASA Astrophysics Data System (ADS)

    Ueda, Kenji; Naito, Michio

    2004-08-01

    We prepared MgB 2 films by coevaporation of pure Mg and B metals in an ultra high vacuum chamber. These films have c-axis orientation and a slightly depressed Tc (∼35 K). We fabricated various tunnel junctions (SIN and SIS) using these as-grown MgB 2 films. Of these, Au/MgO/MgB 2 junctions showed typical SIN characteristics with a clear superconducting gap of Δ∼2.5 meV. This gap value may correspond to the smaller gap in the multi-gap scenario. Preliminary MgB 2/Al 2O 3/MgB 2 junctions exhibited SIS characteristics, although not ideal, with a similar value of Δ.

  18. Multifunctional iron-carbon nanocomposites through an aerosol-based process for the in situ remediation of chlorinated hydrocarbons.

    PubMed

    Zhan, Jingjing; Kolesnichenko, Igor; Sunkara, Bhanukiran; He, Jibao; McPherson, Gary L; Piringer, Gerhard; John, Vijay T

    2011-03-01

    Spherical iron-carbon nanocomposites were developed through a facile aerosol-based process with sucrose and iron chloride as starting materials. These composites exhibit multiple functionalities relevant to the in situ remediation of chlorinated hydrocarbons such as trichloroethylene (TCE). The distribution and immobilization of iron nanoparticles on the surface of carbon spheres prevents zerovalent nanoiron aggregation with maintenance of reactivity. The aerosol-based carbon microspheres allow adsorption of TCE, thus removing dissolved TCE rapidly and facilitating reaction by increasing the local concentration of TCE in the vicinity of iron nanoparticles. The strongly adsorptive property of the composites may also prevent release of any toxic chlorinated intermediate products. The composite particles are in the optimal range for transport through groundwater saturated sediments. Furthermore, those iron-carbon composites can be designed at low cost, the process is amenable to scale-up for in situ application, and the materials are intrinsically benign to the environment.

  19. In situ investigation of the shrinkage of photopolymerized micro/nanostructures: the effect of the drying process.

    PubMed

    Sun, Quan; Ueno, Kosei; Misawa, Hiroaki

    2012-02-15

    We report on experimental study of the shrinkage of photopolymerized micro/nanostructures fabricated by femtosecond direct laser writing in organic-inorganic resists. Blueshift of the stop-band positions of fabricated photonic crystals during the drying process, which follows the development and rinsing stages, indicates that the drying process plays an important role in the formation of the shrinkage. It is further confirmed that the shrinkage almost completely occurs during the drying process by in situ optical monitoring the structures. These findings will help to better understand, control, and even positively utilize the shrinkage in the applications of the photopolymerization-based direct laser writing technique. PMID:22344156

  20. High critical currents in iron-clad superconducting MgB2 wires.

    PubMed

    Jin, S; Mavoori, H; Bower, C; van Dover, R B

    2001-05-31

    Technically useful bulk superconductors must have high transport critical current densities, Jc, at operating temperatures. They also require a normal metal cladding to provide parallel electrical conduction, thermal stabilization, and mechanical protection of the generally brittle superconductor cores. The recent discovery of superconductivity at 39 K in magnesium diboride (MgB2) presents a new possibility for significant bulk applications, but many critical issues relevant for practical wires remain unresolved. In particular, MgB2 is mechanically hard and brittle and therefore not amenable to drawing into the desired fine-wire geometry. Even the synthesis of moderately dense, bulk MgB2 attaining 39 K superconductivity is a challenge because of the volatility and reactivity of magnesium. Here we report the successful fabrication of dense, metal-clad superconducting MgB2 wires, and demonstrate a transport Jc in excess of 85,000 A cm-2 at 4.2 K. Our iron-clad fabrication technique takes place at ambient pressure, yet produces dense MgB2 with little loss of stoichiometry. While searching for a suitable cladding material, we found that other materials dramatically reduced the critical current, showing that although MgB2 itself does not show the 'weak-link' effect characteristic of the high-Tc superconductors, contamination does result in weak-link-like behaviour.

  1. Quantum confinement induced band gaps in MgB2 nanosheets

    NASA Astrophysics Data System (ADS)

    Xu, Bo Z.; Beckman, Scott P.

    2016-09-01

    The discovery of two-dimensional semiconducting materials, a decade ago, spawned an entire sub-field within solid-state physics that is focused on the development of nanoelectronics. Here we present a new class of semiconducting two-dimensional material based on hexagonal MgB2. Although MgB2 is a semimetal, similar to the other well-studied transition metal diborides, we demonstrate that, unlike the transition metal diborides, thinning MgB2, to create nanosheets, opens a band gap in the density of states. We predict that a 7 Å thick MgB2 nanosheet will have a band gap of 0.51 eV. MgB2 nanosheets differ from other two-dimensional semiconductors in that the band gap is introduced by (001) surfaces and is opened by the quantum confinement effect. The implications of these findings are that nanostructured MgB2 is not merely a new composition, but also has intrinsic mechanisms for tuning its electronic properties, which may facilitate the development of nanoelectronics.

  2. Significant enhancement of the superconducting properties of MgB2 by polyvinyl alcohol additives

    NASA Astrophysics Data System (ADS)

    Zeng, R.; Lu, L.; Dou, S. X.

    2008-08-01

    We report a systematic study of the effects of polymer addition on the lattice parameters, microstructure and superconducting properties of MgB2. Polyvinyl alcohol [-C2H4O-]n (PVA) as a typical polymer was used as an additive to MgB2. It was found that PVA additions have the following features: (1) the polymer can have a very low oxygen (O) content or even none at all, and PVA has a low O content (C:O = 2:1), which reduces the impurities brought into MgB2 from the doping, and (2) PVA decomposes at a temperature of 400-650 °C, which means that the reaction occurs in the same temperature range as MgB2 formation, providing highly reactive C, which homogeneously substitutes for B at this low-temperature range. The above considerations significantly enhance the critical current, Jc, the irreversibility field, Hirr, and the upper critical field, Hc2, of MgB2 compared to un-doped samples or those doped with other carbon sources. In this work, suitable PVA doping levels improved both the connectivity and flux pinning, so that the Jc of PVA-doped MgB2 was improved over the whole field range.

  3. Investigation of lauric acid dopant as a novel carbon source in MgB 2 wire

    NASA Astrophysics Data System (ADS)

    Lee, C. M.; Lee, S. M.; Park, G. C.; Joo, J.; Lim, J. H.; Kang, W. N.; Yi, J. H.; Jun, B.-H.; Kim, C.-J.

    2010-11-01

    We fabricated lauric acid (LA) doped MgB 2 wires and investigated the effects of the LA doping. For the fabrication of the LA-doped MgB 2 wires, B powder was mixed with LA at 0-5 wt.% of the total amount of MgB 2 using an organic solvent, dried, and then the LA-treated B and Mg powders were mixed stoichiometrically. The powder mixture was loaded into an Fe tube and the assemblage was drawn and sintered at 900 °C for 3 h under an argon atmosphere. We observed that the LA doping induced the substitution of C for the B sites in MgB 2 and that the actual content of C increased monotonically with increasing LA doping level. The LA-doped MgB 2 wires exhibited a lower critical temperature ( Tc), but better critical current density ( Jc) behavior in a high magnetic field: the 5 wt.% LA-doped sample had a Jc value of 5.32 × 10 3 A/cm 2, which was 2.17 times higher than that of the pristine sample (2.45 × 10 3 A/cm 2) at 5 K and 6 T, suggesting that LA is an effective C dopant in MgB 2 for enhancing the high-field Jc performance.

  4. Recent achievements in MgB 2 physics and applications: A large-area SQUID magnetometer and point-contact spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Gonnelli, R. S.; Daghero, D.; Calzolari, A.; Ummarino, G. A.; Tortello, M.; Stepanov, V. A.; Zhigadlo, N. D.; Rogacki, K.; Karpinski, J.; Portesi, C.; Monticone, E.; Mijatovic, D.; Veldhuis, D.; Brinkman, A.

    2006-03-01

    In the first part of the present paper we discuss the fabrication and the characterization of an MgB2-based SQUID magnetometer with a directly coupled large-area pick-up loop, made on an MgB2 film deposited by an all in situ technique. The coarse structure of the SQUID was defined by optical lithography and Ar-ion milling, while the two nanobridges acting as weak links in the superconducting loop were made by focused ion beam (FIB) milling. The device was characterized at different temperatures and showed Josephson quantum interference up to 20 K as well as a noise level already compatible with the recording of an adult magnetocardiogram. In the second part, concerning the fundamental physics of MgB2, we present the results of very recent point-contact measurements on Mg1-xMnxB2 single crystals with 34.1 ⩾ Tc ⩾ 13.3 K (i.e. 0.37% ⩽ x ⩽ 1.5%). The experimental conductance curves were fitted with the generalized two-band BTK model and their behaviour in magnetic fields was studied to check if both the order parameters (OPs) of the σ and π bands were present in the whole doping range. The dependence of the OPs (evaluated through the fit) on the Andreev critical temperature of the junctions is analyzed in the framework of the two-band Eliashberg theory by including the effects of magnetic impurities. The results give an evidence of a dominant effect of the magnetic impurities on the σ-band channel.

  5. Flux pinning behavior of MgB2 doped with Fe and Fe2O3 nanowires

    NASA Astrophysics Data System (ADS)

    Ke, C.; Cheng, C. H.; Yang, Y.; Zhang, Y.; Wang, W. T.; Zhao, Y.

    MgB2 bulks doped with Fe and Fe2O3 nanowires are prepared by hybridized diffusion method. The doping effect on superconductivity transition temperature, Tc, critical current density Jc, and flux pinning behavior have been studied. It is found that both Tc and Jc of MgB2 show quite different features for these two kinds of nanowires. Fe2O3 nanowires significantly suppress both Tc and Jc of MgB2, whereas Fe nanowires do improve the flux pining behavior of MgB2 although the Tc is slightly suppressed.

  6. In-Situ Anaerobic Biosurfactant Production Process For Remediation Of DNAPL Contamination In Subsurface Aquifers

    NASA Astrophysics Data System (ADS)

    Albino, J. D.; Nambi, I. M.

    2009-12-01

    Microbial Enhanced Oil Recovery (MEOR) and remediation of aquifers contaminated with hydrophobic contaminants require insitu production of biosurfactants for mobilization of entrapped hydrophobic liquids. Most of the biosurfactant producing microorganisms produce them under aerobic condition and hence surfactant production is limited in subsurface condition due to lack of oxygen. Currently bioremediation involves expensive air sparging or excavation followed by exsitu biodegradation. Use of microorganisms which can produce biosurfactants under anaerobic conditions can cost effectively expedite the process of insitu bioremediation or mobilization. In this work, the feasibility of anaerobic biosurfactant production in three mixed anaerobic cultures prepared from groundwater and soil contaminated with chlorinated compounds and municipal sewage sludge was investigated. The cultures were previously enriched under complete anaerobic conditions in the presence of Tetrachloroethylene (PCE) for more than a year before they were studied for biosurfactant production. Biosurfactant production under anaerobic conditions was simulated using two methods: i) induction of starvation in the microbial cultures and ii) addition of complex fermentable substrates. Positive result for biosurfactant production was not observed when the cultures were induced with starvation by adding PCE as blobs which served as the only terminal electron acceptor. However, slight reduction in interfacial tension was noticed which was caused by the adherence of microbes to water-PCE interface. Biosurfactant production was observed in all the three cultures when they were fed with complex fermentable substrates and surface tension of the liquid medium was lowered below 35 mN/m. Among the fermentable substrates tested, vegetable oil yielded highest amount of biosurfactant in all the cultures. Complete biodegradation of PCE to ethylene at a faster rate was also observed when vegetable oil was amended to the

  7. Effect of the sand grain specific surface area on the performance of the tube in-situ combustion process

    SciTech Connect

    Vossoughi, S.; Bartlett, G.; Wilhite, G.P.

    1982-09-01

    The influence of the porous matrix on in-situ combustion has been recognized by many investigators as an important part of the process. Clays are of particular interest because they are abundant in sandstones and affect the combustion process through two mechanisms: large surface area per unit mass and catalytic properties. This study concerns surface area effects on in-situ combustion. Catalytic effects were excluded by conducting experiments using silica sand with variable specific surface area as the porous medium. Studies were made using an in-situ combustion tube and thermogravimetric analysis. In-situ combustion tube runs were made with silica sands of different grain sizes. Specific surface area ranged from 76 to 3332 cm/sup 2//g. This corresponds to average sand particle diameters ranging from 210 to 7.3 microns respectively. All the other variables were kept constant. The combustion front was not self-sustained at low surface area. A strong, sustained combustion front was observed at high surface area. Thermogravimetric Analysis (TGA) was applied to the samples taken at 1 to 2 inch intervals ahead of the front to study crude oil distribution. In the case of unsuccessful runs, the amount of the crude oil ahead of the front decreased to a level that sufficient fuel could not be laid down to sustain the front. In the self-sustained run (highest surface area) crude oil content immediately ahead of the front was even higher than the original sand/oil mixture. Therefore a minimum surface area is required to provide conditions for sufficient fuel to be laid down by coking process.

  8. Preparation and characterisation of Ru doped MgB2

    NASA Astrophysics Data System (ADS)

    Grivel, J.-C.; Holte, O. J.

    2013-12-01

    Samples with Mg1-xRuxB2 nominal stoichiometry were prepared by sintering at 800 °C. The critical transition temperature decreases up to a substitution level of x ≈ 0.015. A maximum solubility limit slightly in excess of 1 at.% Ru for Mg is confirmed by energy dispersive spectroscopy measurements. From and beyond this limit, an unidentified phase appears in the X-ray diffraction patterns. Interestingly, the lattice parameters of the MgB2 phase are constant up to x = 0.015, but start to decrease for higher Ru contents. This feature could be related to the fact that a Mg-Ru impurity phase results in a Mg-deficient (Mg,Ru)B2 matrix.

  9. Scanning tunneling spectroscopy in MgB2.

    PubMed

    Karapetrov, G; Iavarone, M; Kwok, W K; Crabtree, G W; Hinks, D G

    2001-05-01

    We present scanning tunneling microscopy measurements of the surface of superconducting MgB2 with a critical temperature of 39 K. In zero magnetic field the conductance spectra can be analyzed in terms of the standard BCS theory with a smearing parameter gamma. The value of the superconducting gap is 5 meV at 4.2 K, with no experimentally significant variation across the surface of the sample. The temperature dependence of the gap follows the BCS form, fully consistent with phonon-mediated superconductivity in this novel superconductor. The application of a magnetic field induces strong pair breaking as seen in the conductance spectra in fields up to 6 T.

  10. Preparation and characterisation of Os doped MgB2

    NASA Astrophysics Data System (ADS)

    Grivel, J.-C.; Namazkar, S.; Alexiou, A.; Holte, O. J.

    2014-12-01

    Polycrystalline samples with Mg1-xOsxB2.04 nominal stoichiometry were made by reacting elemental powders at 800 °C under argon atmosphere. Based on XRD diffraction patterns, EDS analysis and magnetisation measurements, it is found that Os can replace up to about 1 at.% Mg in the MgB2 lattice. Beyond this doping level, unreacted Os and Mg-rich Mg-Os impurity phases are formed. The a-axis parameter contracts upon doping while the superconducting transition temperature decreases at a rate of 2.1 K/at.% Os substitution. At 10 K, Os doping induces an improvement of the normalised critical current density under applied magnetic fields in excess of 0.5 T, indicating a modest enhancement of flux pinning in this range.

  11. Thermographic in-situ process monitoring of the electron-beam melting technology used in additive manufacturing

    NASA Astrophysics Data System (ADS)

    Dinwiddie, Ralph B.; Dehoff, Ryan R.; Lloyd, Peter D.; Lowe, Larry E.; Ulrich, Joe B.

    2013-05-01

    Oak Ridge National Laboratory (ORNL) has been utilizing the ARCAM electron beam melting technology to additively manufacture complex geometric structures directly from powder. Although the technology has demonstrated the ability to decrease costs, decrease manufacturing lead-time and fabricate complex structures that are impossible to fabricate through conventional processing techniques, certification of the component quality can be challenging. Because the process involves the continuous deposition of successive layers of material, each layer can be examined without destructively testing the component. However, in-situ process monitoring is difficult due to metallization on inside surfaces caused by evaporation and condensation of metal from the melt pool. This work describes a solution to one of the challenges to continuously imaging inside of the chamber during the EBM process. Here, the utilization of a continuously moving Mylar film canister is described. Results will be presented related to in-situ process monitoring and how this technique results in improved mechanical properties and reliability of the process.

  12. Microstructures of Metallic NiCrBSi Coatings Manufactured via Hybrid Plasma Spray and In Situ Laser Remelting Process

    NASA Astrophysics Data System (ADS)

    Serres, Nicolas; Hlawka, Françoise; Costil, Sophie; Langlade, Cécile; Machi, Frédérique

    2011-01-01

    This paper deals with coating alternatives to hard chromium plating. Thermal spraying is already used in industry, but results are not always satisfactory for reasons of porosity and microstructures. In this study, atmospheric plasma spraying (APS) and in situ laser irradiation by diode laser processes were combined to modify the structural characteristics of thick NiCrBSi alloy layers. The microstructure evolution was studied, and results show that in situ laser remelting induced the growth of a dendritic structure, which strongly decreased the porosity of as-sprayed coatings and increased the adhesion on the substrate. Moreover, no phase transition after laser treatment was observed. Lastly, a mechanical investigation demonstrated that the combination between plasma spray and in situ melting with a diode laser could result in very good mechanical properties. The increase of the laser incident power involved an increase of the mean contact pressure, along with coating hardness. The hybrid process appears to be a possible alternative to hard chromium plating, in order to protect mechanical parts, because of the improved mechanical properties of the NiCrBSi layer.

  13. Sailing into uncharted waters: recent advances in the in situ monitoring of catalytic processes in aqueous environments

    SciTech Connect

    Shi, Hui; Lercher, Johannes A.; Yu, Xiao-Ying

    2015-01-01

    Catalysis in aqueous environments is attracting enormous interest. Many characterization methods are well established at gas-solid interfaces and a majority of the surface-science approaches were historically limited to model surfaces and vacuum conditions. However, practical scenarios with complex catalyst structures, elevated temperatures and pressures, as well as the presence of two or more condensed phases, can pose significant challenges to these techniques, particularly for catalysts at their dynamic working states. In such contexts, this review highlights the advances over the past five years in the in situ and real-time detection of catalytic processes and related phenomena in aqueous media, ideally under realistic conditions. We underline latest technical innovations, describe novel chemistries that are made accessible by recently developed toolboxes, and discuss future directions of in situ and time-resolved analytical approaches applicable to aqueous phase catalysis.

  14. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    NASA Astrophysics Data System (ADS)

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sönke; Schlepütz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  15. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    SciTech Connect

    Klug, Jeffrey A. Emery, Jonathan D.; Martinson, Alex B. F.; Proslier, Thomas; Weimer, Matthew S.; Yanguas-Gil, Angel; Elam, Jeffrey W.; Seifert, Sönke; Schlepütz, Christian M.; Hock, Adam S.

    2015-11-15

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er{sub 2}O{sub 3} ALD on amorphous ALD alumina and single crystalline sapphire.

  16. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes.

    PubMed

    Klug, Jeffrey A; Weimer, Matthew S; Emery, Jonathan D; Yanguas-Gil, Angel; Seifert, Sönke; Schlepütz, Christian M; Martinson, Alex B F; Elam, Jeffrey W; Hock, Adam S; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  17. A modular reactor design for in situ synchrotron X-ray investigation of atomic layer deposition processes

    SciTech Connect

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sonke; Schleputz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present \\textit{in situ} results for 1.) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, 2.) grazing-incidence small angle scattering of MnO nucleation on silicon, and 3.) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  18. A Modular Ex Situ Conversion Process for Thick MOD-Fluoride RBCO Precursors

    SciTech Connect

    Feenstra, Roeland; List III, Frederick Alyious; Li, Xiaoping; Rupich, Marty; Miller, D. J.; Maroni, Victor A.; Zhang, Yifei; Thompson, James R; Christen, David K

    2009-01-01

    Following a review of heating induced chemical and structural changes in RBa2Cu3O7 (RBCO) fluoride precursors (R= rare earth of Y) deposited by metalorganic (MOD) and physical vapor deposition (PVD), a modular process comprising successive, functionally distinct, brief annealing steps (modules) is introduced. By decoupling events that otherwise occur simultaneously, the modular process provides a framework for addressing the complex kinetics associated with the temperature ramp of the ex situ conversion anneal. Modules for modifying the F concentration, porosity and microstructure, and RBCO nucleation are described.

  19. Determining the locus of a processing zone in an in situ oil shale retort by sound monitoring

    DOEpatents

    Elkington, W. Brice

    1978-01-01

    The locus of a processing zone advancing through a fragmented permeable mass of particles in an in situ oil shale retort in a subterranean formation containing oil shale is determined by monitoring for sound produced in the retort, preferably by monitoring for sound at at least two locations in a plane substantially normal to the direction of advancement of the processing zone. Monitoring can be effected by placing a sound transducer in a well extending through the formation adjacent the retort and/or in the fragmented mass such as in a well extending into the fragmented mass.

  20. Water dissociation in a radio-frequency electromagnetic field with ex situ electrodes—process characterization

    NASA Astrophysics Data System (ADS)

    Schneider, Jens; Holzer, Frank; Kraus, Markus; Kopinke, Frank-Dieter; Roland, Ulf

    2013-02-01

    A new type of water dissociation at ambient pressure initiated by the irradiation of aqueous electrolytes using an electromagnetic field with a frequency of 13.56 MHz is described in this study. A special reactor design allows the use of ex situ electrodes to form in situ electrical discharges in water vapour bubbles. The observed formation of molecular hydrogen (H2) and oxygen (O2) combined with the emission of light (‘burning water’ phenomenon) originates from a non-thermal plasma in water vapour bubbles. The influences of type of electrolyte, its concentration, pH value and external RF voltage on the gas formation rate as well as on the gas composition are presented.

  1. Direct in situ observations of single Fe atom catalytic processes and anomalous diffusion at graphene edges.

    PubMed

    Zhao, Jiong; Deng, Qingming; Avdoshenko, Stanislav M; Fu, Lei; Eckert, Jürgen; Rümmeli, Mark H

    2014-11-01

    Single-atom catalysts are of great interest because of their high efficiency. In the case of chemically deposited sp(2) carbon, the implementation of a single transition metal atom for growth can provide crucial insight into the formation mechanisms of graphene and carbon nanotubes. This knowledge is particularly important if we are to overcome fabrication difficulties in these materials and fully take advantage of their distinct band structures and physical properties. In this work, we present atomically resolved transmission EM in situ investigations of single Fe atoms at graphene edges. Our in situ observations show individual iron atoms diffusing along an edge either removing or adding carbon atoms (viz., catalytic action). The experimental observations of the catalytic behavior of a single Fe atom are in excellent agreement with supporting theoretical studies. In addition, the kinetics of Fe atoms at graphene edges are shown to exhibit anomalous diffusion, which again, is in agreement with our theoretical investigations.

  2. Aqueous dissolution of laboratory and field samples from the in-situ vitrification process

    SciTech Connect

    McGrail, B.P. ); Bates, S.O. )

    1991-08-01

    In-situ vitrification (ISV) is being evaluated in several countries as a remediation technology for immobilizing both hazardous and radioactive buried wastes. A combination of laboratory data and modeling results are presented that establishes the scientific basis for predicting the long-term stability of an ISV glass in the environment. Laboratory experiments included tests with ISV samples obtained from pilot- and intermediate-scale field tests, a nuclear waste glass, and a natural obsidian. 8 refs.

  3. In situ flash x-ray high-speed computed tomography for the quantitative analysis of highly dynamic processes

    NASA Astrophysics Data System (ADS)

    Moser, Stefan; Nau, Siegfried; Salk, Manfred; Thoma, Klaus

    2014-02-01

    The in situ investigation of dynamic events, ranging from car crash to ballistics, often is key to the understanding of dynamic material behavior. In many cases the important processes and interactions happen on the scale of milli- to microseconds at speeds of 1000 m s-1 or more. Often, 3D information is necessary to fully capture and analyze all relevant effects. High-speed 3D-visualization techniques are thus required for the in situ analysis. 3D-capable optical high-speed methods often are impaired by luminous effects and dust, while flash x-ray based methods usually deliver only 2D data. In this paper, a novel 3D-capable flash x-ray based method, in situ flash x-ray high-speed computed tomography is presented. The method is capable of producing 3D reconstructions of high-speed processes based on an undersampled dataset consisting of only a few (typically 3 to 6) x-ray projections. The major challenges are identified, discussed and the chosen solution outlined. The application is illustrated with an exemplary application of a 1000 m s-1 high-speed impact event on the scale of microseconds. A quantitative analysis of the in situ measurement of the material fragments with a 3D reconstruction with 1 mm voxel size is presented and the results are discussed. The results show that the HSCT method allows gaining valuable visual and quantitative mechanical information for the understanding and interpretation of high-speed events.

  4. Studies of ferroelectric heterostructure thin films, interfaces, and device-related processes via in situ analytical techniques.

    SciTech Connect

    Aggarwal, S.; Auciello, O.; Dhote, A. M.; Gao, Y.; Gruen, D. M.; Im, J.; Irene, E. A.; Krauss, A. R.; Muller, A. H.; Ramesh, R.

    1999-06-29

    The science and technology of ferroelectric thin films has experienced an explosive development during the last ten years. Low-density non-volatile ferroelectric random access memories (NVFRAMS) are now incorporated in commercial products such as ''smart cards'', while high permittivity capacitors are incorporated in cellular phones. However, substantial work is still needed to develop materials integration strategies for high-density memories. We have demonstrated that the implementation of complementary in situ characterization techniques is critical to understand film growth and device processes relevant to device development. We are using uniquely integrated time of flight ion scattering and recoil spectroscopy (TOF-ISARS) and spectroscopic ellipsometry (SE) techniques to perform in situ, real-time studies of film growth processes in the high background gas pressure required to growth ferroelectric thin films. TOF-ISARS provides information on surface processes, while SE permits the investigation of buried interfaces as they are being formed. Recent studies on SrBi{sub 2}Ta{sub 2}O{sub 9} (SBT) and Ba{sub x}Sr{sub 1{minus}x}TiO{sub 3} (BST) film growth and interface processes are discussed. Direct imaging of ferroelectric domains under applied electric fields can provide valuable information to understand domain dynamics in ferroelectric films. We discuss results of piezoresponse scanning force microscopy (SFM) imaging for nanoscale studies of polarization reversal and retention loss in Pb(Zr{sub x}Ti{sub 1{minus}x})O{sub 3} (PZT)-based capacitors. Another powerful technique suitable for in situ, real-time characterization of film growth processes and ferroelectric film-based device operation is based on synchrotrons X-ray scattering, which is currently being implemented at Argonne National Laboratory.

  5. EPA site demonstration of the international waste technologies/Geo-Con in-situ stabilization/solidification process

    SciTech Connect

    Stinson, M.K.

    1990-11-01

    The paper presents an EPA evaluation of the first field demonstration of an in situ stabilization/solidification process for contaminated soil under the EPA Superfund Innovative Technology Evaluation (SITE) program. Demonstration of the process was a joint effort of two vendors: International Waste Technologies' (IWT) of Wichita, Kansas, who provided the treatment process, specifically the proprietary additive called HWT-20, and Geo-Con, Inc., of Pittsburgh, Pennsylvania, who provided both engineering and hardware for the in situ soil treatment. The field demonstration took place in April, 1988 at a site contaminated mainly with polychlorinated biphenyls (PCBs). EPA tested the soil before and after treatment and the EPA evaluation of the process is based on results from the testing. A year later, in April 1989, EPA tested again the treated soil and results of that testing were compared to those of the demonstration. Results of the EPA evaluation of the IWT process, the Geo-Con performance, and treatment costs are discussed separately.

  6. Assessment of liquid hydrogen cooled MgB2 conductors for magnetically confined fusion

    NASA Astrophysics Data System (ADS)

    Glowacki, B. A.; Nuttall, W. J.

    2008-02-01

    Importantly environmental factors are not the only policy-driver for the hydrogen economy. Over the timescale of the development of fusion energy systems, energy security issues are likely to motivate a shift towards both hydrogen production and fusion as an energy source. These technologies combine local control of the system with the collaborative research interests of the major energy users in the global economy. A concept Fusion Island Reactor that might be used to generate H2 (rather than electricity) is presented. Exploitation of produced hydrogen as a coolant and as a fuel is proposed in conjunction with MgB2 conductors for the tokomak magnets windings, and electrotechnical devices for Fusion Island's infrastructure. The benefits of using MgB2 over the Nb-based conductors during construction, operation and decommissioning of the Fusion Island Reactor are presented. The comparison of Nb3Sn strands for ITER fusion magnet with newly developed high field composite MgB2 PIT conductors has shown that at 14 Tesla MgB2 possesses better properties than any of the Nb3Sn conductors produced. In this paper the potential of MgB2 conductors is examined for tokamaks of both the conventional ITER type and a Spherical Tokamak geometry. In each case MgB2 is considered as a conductor for a range of field coil applications and the potential for operation at both liquid helium and liquid hydrogen temperatures is considered. Further research plans concerning the application of MgB2 conductors for Fusion Island are also considered.

  7. Application of superconducting magnesium diboride (MGB2) in superconducting radio frequency cavities

    NASA Astrophysics Data System (ADS)

    Tan, Teng

    The superconductivity in magnesium diboride (MgB2) was discovered in 2001. As a BCS superconductor, MgB2 has a record-high Tc of 39 K, high Jc of > 107 A/cm2 and no weak link behavior across the grain boundary. All these superior properties endorsed that MgB2 would have great potential in both power applications and electronic devices. In the past 15 years, MgB2 based power cables, microwave devices, and commercial MRI machines emerged and the next frontier are superconducting radio frequency (SRF) cavities. SRF cavities are one of the leading accelerator technologies. In SRF cavities, applied microwave power generates electrical fields that accelerate particle beams. Compared with other accelerator techniques, SRF cavity accelerators feature low loss, high acceleration gradients and the ability to accelerate continuous particle beams. However, current SRF cavities are made from high-purity bulk niobium and work at 2 K in superfluid helium. The construction and operational cost of SRF cavity accelerators are very expensive. The demand for SRF cavity accelerators has been growing rapidly in the past decade. Therefore, a lot of effort has been devoted to the enhancement of the performance and the reduction of cost of SRF cavities. In 2010, an acceleration gradient of over 50 MV/m has been reported for a Nb-based SRF cavity. The magnetic field at the inner surface of such a cavity is ~ 1700 Oe, which is close to the thermodynamic critical field of Nb. Therefore, new materials and technologies are required to raise the acceleration gradient of future SRF cavity accelerators. Among all the proposed approaches, using MgB2 thin films to coat the inner surface of SRF cavities is one of the promising tactics with the potential to raise both the acceleration gradient and the operation temperature of SRF cavity accelerators. In this work, I present my study on MgB2 thin films for their application in SRF cavities. C-epitaxial MgB2 thin films grown on SiC(0001) substrates

  8. Development of CFD-Based Simulation Tools for In-Situ Thermal Processing of Oil Shale/Sands

    SciTech Connect

    None, None

    2012-02-01

    In our research, we are taking the novel approach of developing and applying high performance computing, computational fluid dynamics (CFD)-based simulation tools to a modified in-situ process for production of oil from oil shale. The simulation tools being developed capture the relevant physical processes and data from a large-scale system. The modified in-situ application is a pilot-scale heat transfer process inside Red Leaf Resources EcoShale capsule. We demonstrate the need to understand fluid flow behavior in the convective channels of the rubblized shale bed as convective heating greatly decreases the time required to heat the oil shale to the production temperature when compared with conductive heating alone. We have developed and implemented a geometry creation strategy for a representative section of the EcoShale capsule, developed a meshing approach to deal with the complicated geometry and produce a well-behaved mesh, analyzed the effects of boundary conditions on the simulation results, and devised a new operator splitting solution algorithm that reduces computational costs by taking advantage of the differing convective and conductive time scales occurring in the simulation. These simulation tools can be applied to a wide range of processes involving convective fluid flow heating in rubblized beds.

  9. In situ optical diagnostics of growing surfaces in the process of nanoheterostructure fabrication

    SciTech Connect

    Kazakov, I. P. Glazyrin, E. V.; Savinov, S. A.; Tsekhosh, V. I.; Shmelev, S. S.

    2010-11-15

    It is demonstrated that in situ reflectance and reflectance-anisotropy measurements can be used as efficient real-time monitoring tools for all stages of the growth of heterostructures with ultrathin (few-monolayer) GaAs and AlAs layers. Changes in the layer composition at normal GaAs/AlAs interfaces in the active region of resonant-tunneling diode structures are detected with a thickness resolution on the order of one monolayer. Resonant-tunneling diodes with a peak-to-valley ratio of 3.3 and peak current density of 6.6 x 10{sup 4} A/cm{sup 2} are fabricated.

  10. Identification of TRAK1 (Trafficking protein, kinesin-binding 1) as MGb2-Ag: a novel cancer biomarker.

    PubMed

    Zhang, Faming; Ren, Gui; Lu, Yuanyuan; Jin, Bin; Wang, Jun; Chen, Xiong; Liu, Zhenxiong; Li, Kai; Nie, Yongzhan; Wang, Xin; Fan, Daiming

    2009-02-18

    The present study aimed to describe the characterization of an antibody MGb2 that reacts with an epitope on gastric cancer cells, and identification of MGb2 antigen (MGb2-Ag). Immunostaining revealed its distribution in human tissues and demonstrated that the positive rate of MGb2-Ag was 81.48% in gastric cancer, 100% in gastric signet-ring cell carcinoma and mucinous adenocarcinoma, 13.16% in precancerous conditions, and 0% in chronic superficial gastritis. Using Western blotting, immunoprecipitation and MALDI-TOF MS (matrix assisted laser desorption/ionization time-of-flight mass spectrometry), MGb2-Ag was identified as TRAK1 (Trafficking protein, kinesin-binding 1), a new molecular gained limited recognition. Both MGb2 and commercial anti-TRAK1 Ab recognized prokaryotic expressed TRAK1. Immunostaining characteristics of TRAK1 were identical with MGb2-Ag in continuous sections of paraffin-embedded tissues of gastric tissues. This is the first report that TRAK1/MGb2-Ag is a promising diagnostic marker for gastric cancer and may help to detect signet-ring cell carcinoma and mucinous adenocarcinoma.

  11. Flux jump behaviors and mechanism of FeTi doped MgB2 at 5 K

    NASA Astrophysics Data System (ADS)

    Lee, H. B.; Kim, G. C.; Kim, Y. C.; Ahmad, D.

    2015-08-01

    This study examined the flux jump behaviors of Fe-doped MgB2 according to content of FeTi particles at 5 K, at which flux jump has been shown to be more frequent. The samples were synthesized in a stainless steel tube with Mg, B and FeTi particles. The motives of flux jump in MgB2 superconductors are over-moving fluxes around the defects and the low heat capacity of MgB2. MgB2 was doped with FeTi particles to overcome these vulnerable points of MgB2. The flux jump of MgB2 decreased with increasing content of doped FeTi particles. On the other hand, excessive doping of FeTi resulted in a decrease of diamagnetic properties and the flux pinning effects together. It is concluded that FeTi particles in MgB2 do not block the flux jump itself, but the propagation of flux jump of MgB2.

  12. Laser processing of in situ TiN/Ti composite coating on titanium.

    PubMed

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding.

  13. Laser processing of in situ TiN/Ti composite coating on titanium.

    PubMed

    Sahasrabudhe, Himanshu; Soderlind, Julie; Bandyopadhyay, Amit

    2016-01-01

    Laser remelting of commercially pure titanium (CP-Ti) surface was done in a nitrogen rich inert atmosphere to form in situ TiN/Ti composite coating. Laser surface remelting was performed at two different laser powers of 425 W and 475 W. At each power, samples were fabricated with one or two laser scans. The resultant material was a nitride rich in situ coating that was created on the surface. The cross sections revealed a graded microstructure. There was presence of nitride rich dendrites dispersed in α-Ti matrix at the uppermost region. The structure gradually changed with lesser dendrites and more heat affected α-Ti phase maintaining a smooth interface. With increasing laser power, the dendrites appeared to be larger in size. Samples with two laser scans showed discontinuous dendrites and more α-Ti phase as compared to the samples with one laser scan. The resultant composite of TiN along with Ti2N in α-Ti showed substantially higher hardness and wear resistance than the untreated CP-Ti substrate. Coefficient of friction was also found to reduce due to surface nitridation. Leaching of Ti(4+) ions during wear test in DI water medium was found to reduce due to laser surface nitriding. PMID:26344856

  14. In situ biosynthesis of bacterial nanocellulose-CaCO3 hybrid bionanocomposite: One-step process.

    PubMed

    Mohammadkazemi, Faranak; Faria, Marisa; Cordeiro, Nereida

    2016-08-01

    In this work, a simple and green route to the synthesis of the bacterial nanocellulose-calcium carbonate (BNC/CaCO3) hybrid bionanocomposites using one-step in situ biosynthesis was studied. The CaCO3 was incorporated in the bacterial nanocellulose structure during the cellulose biosynthesis by Gluconacetobacter xylinus PTCC 1734 bacteria. Hestrin-Schramm (HS) and Zhou (Z) culture media were used to the hybrid bionanocomposites production and the effect of ethanol addition was investigated. Attenuated total reflection Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, inverse gas chromatography and thermogravimetric analysis were used to characterize the samples. The experimental results demonstrated that the ethanol and culture medium play an important role in the BNC/CaCO3 hybrid bionanocomposites production, structure and properties. The BNC/CaCO3 biosynthesized in Z culture medium revealed higher O/C ratio and amphoteric surface character, which justify the highest CaCO3 content incorporation. The CaCO3 was incorporated into the cellulosic matrix decreasing the bacterial nanocellulose crystallinity. This work reveals the high potential of in situ biosynthesis of BNC/CaCO3 hybrid bionanocomposites and opens a new way to the high value-added applications of bacterial nanocellulose. PMID:27157766

  15. In-Situ XAFS Characterization for Nitriding Process of Silica Supported Nb Catalysts Under N2-H2 Gas

    SciTech Connect

    Ichikuni, Nobuyuki; Matsumoto, Hiroari; Haneishi, Hidenori; Shimazu, Shogo; Bando, Kyoko K.

    2007-02-02

    Fe-Nb/SiO2 catalyst was prepared from NbCl5 or peroxoniobic acid as Nb precursors. These precursor catalysts were nitrided by the TPR method under N2-H2 passage (without using NH3). Nb K-edge in-situ XAFS measurements were carried out during the nitriding process and revealed that the Nb species was more nitrided in the Fe-Nb/SiO2 catalyst prepared from peroxoniobic acid than in that prepared from NbCl5 as Nb precursor.

  16. In-Situ XAFS Characterization for Nitriding Process of Silica Supported Nb Catalysts Under N2-H2 Gas

    NASA Astrophysics Data System (ADS)

    Ichikuni, Nobuyuki; Matsumoto, Hiroari; Haneishi, Hidenori; Bando, Kyoko K.; Shimazu, Shogo

    2007-02-01

    Fe-Nb/SiO2 catalyst was prepared from NbCl5 or peroxoniobic acid as Nb precursors. These precursor catalysts were nitrided by the TPR method under N2-H2 passage (without using NH3). Nb K-edge in-situ XAFS measurements were carried out during the nitriding process and revealed that the Nb species was more nitrided in the Fe-Nb/SiO2 catalyst prepared from peroxoniobic acid than in that prepared from NbCl5 as Nb precursor.

  17. Theoretical investigation of superconductivity in MgB2-xCx alloys

    NASA Astrophysics Data System (ADS)

    Sharma, Gargee; Sharma, Smita

    2016-05-01

    In this paper we investigated the superconducting properties of MgB2-xCx alloys where x is the concentration (0.0, 0.03, 0.11 and 0.20). The superconducting state parameters, namely, the electron-phonon coupling strength (λ), Coulomb pseudopotential (μ*), transition temperature (Tc), isotope effect exponent (α) and interaction strength (NoV) of MgB2-xCx alloys have been investigated in the BCS-Eliashberg-McMillan framework, as modified for MgB2-xCx alloys. Pseudo ions with average properties have been considered to replace different types of ions in the system. It is observed that all the superconducting parameters go on decreasing as the concentration of C is increased. The magnitudes of λ and Tc indicate that MgB2-xCx is strong-to-intermediate coupling superconductor. It is also observed that Tc is composition dependent. Present computations yield almost linear variation of Tc with concentration x of C in the MgB2-xCx system, which is in agreement with the experimental data. A linear Tc equation is proposed by fitting the present results.

  18. Evaluations of MgB2 Coatings on 2'' Copper Discs for Superconducting Radio Frequency Applications

    NASA Astrophysics Data System (ADS)

    Withanage, Wenura; Tan, Teng; Lee, Namhoon; Banjade, Huta; Eremeev, Grigory; Welander, Paul; Valente-Feliciano, Anne-Marie; Kustom, Robert; Wolak, Matthäus; Nassiri, Alireza; Xi, Xiaoxing

    We propose that coating the inner walls of copper RF cavities with superconducting MgB2 (Tc = 39 K) can result in a viable alternative to the already established niobium-based SRF technology. This approach improves the thermal conductivity, allows for operation at higher temperatures, and reduces the need for large helium refrigeration, thereby resulting in lower operational costs. For our studies, we grew MgB2 films via hybrid physical chemical vapor deposition (HPCVD) on 2'' Cu substrates. Since Mg and Cu readily form an alloy at higher temperatures, the HPCVD setup was modified in order to achieve lower deposition temperatures, minimize alloy formation, and provide high quality MgB2 films. This method yielded MgB2 coatings on 2'' Cu discs with transition temperatures around 38 K. The samples were characterized with regards to their RF attributes and showed similar performance in comparison to Nb reference samples. The presented results show that MgB2 coated copper can be a suitable alternative for use in SRF cavities.

  19. Assessing microbial processes in deep-sea hydrothermal systems by incubation at in situ temperature and pressure

    NASA Astrophysics Data System (ADS)

    McNichol, Jesse; Sylva, Sean P.; Thomas, François; Taylor, Craig D.; Sievert, Stefan M.; Seewald, Jeffrey S.

    2016-09-01

    At deep-sea hydrothermal vents, a large source of potential chemical energy is created when reducing vent fluid and oxidizing seawater mix. In this environment, chemolithoautotrophic microbes catalyze exergonic redox reactions which in turn provide the energy needed to fuel their growth and the fixation of CO2 into biomass. In addition to producing new organic matter, this process also consumes compounds contained both in vent fluid and entrained seawater (e.g. H2, NO3-). Despite their biogeochemical importance, such reactions have remained difficult to quantify due to methodological limitations. To address this knowledge gap, this study reports a novel application of isobaric gas-tight fluid samplers for conducting incubations of hydrothermal vent fluids at in situ temperature and pressure. Eighteen ~24 h incubations were carried out, representing seven distinct conditions that examine amendments consisting of different electron donors and acceptors. Microbial activity was observed in all treatments, and time series chemical measurements showed that activity was limited by electron acceptor supply, confirming predictions based on geochemical data. Also consistent with these predictions, the presence of nitrate increased rates of hydrogen consumption and yielded ammonium as a product of nitrate respiration. The stoichiometry of predicted redox reactions was also determined, revealing that the sulfur and nitrogen cycles are incompletely understood at deep-sea vents, and likely involve unknown intermediate redox species. Finally, the measured rates of redox processes were either equal to or far greater than what has been reported in previous studies where in situ conditions were not maintained. In addition to providing insights into deep-sea hydrothermal vent biogeochemistry, the methods described herein also offer a practical approach for the incubation of any deep-sea pelagic sample under in situ conditions.

  20. Influence of twisting and bending on the Jc and n-value of multifilamentary MgB2 strands

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Li, G.; Susner, M.; Sumption, M. D.; Rindfleisch, M.; Tomsic, M.; Collings, E. W.

    2015-12-01

    The influences of strand twisting and bending (applied at room temperature) on the critical current densities, Jc, and n-values of MgB2 multifilamentary strands were evaluated at 4.2 K as function of applied field strength, B. Three types of MgB2 strand were evaluated: (i) advanced internal magnesium infiltration (AIMI)-processed strands with 18 filaments (AIMI-18), (ii) powder-in-tube (PIT) strands processed using a continuous tube forming and filling (CTFF) technique with 36 filaments (PIT-36) and (iii) CTFF processed PIT strands with 54 filaments (PIT-54). Transport measurements of Jc(B) and n-value at 4.2 K in fields of up to 10 T were made on: (i) PIT-54 after it was twisted (at room temperature) to twist pitch values, Lp, of 10-100 mm. Transport measurements of Jc(B) and n-value were performed at 4.2 K; (ii) PIT-36 and AIMI-18 after applying bending strains up to 0.6% at room temperature. PIT-54 twisted to pitches of 100 mm down to 10 mm exhibited no degradation in Jc(B) and only small changes in n-value. Both the Jc(B) and n-value of PIT-36 were seen to be tolerant to bending strain of up to 0.4%. On the other hand, AIMI-18 showed ±10% changes in Jc(B) and significant scatter in n-value over the bending strain range of 0-0.6%.

  1. Critical Currents, Vortex Dynamics and Microstructure in MgB_2

    NASA Astrophysics Data System (ADS)

    Serquis, Adriana; Civale, Leonardo; Liao, Xiazhou; Maley, Martin; Zhu, Yuntian; Peterson, Dean; Mueller, Fred

    2003-03-01

    One key issue in optimizing critical current density in MgB2 is to determine which structural features are the relevant pinning centers. In this work we explore the influence of microstructures on the vortex dynamics of bulk samples prepared either at ambient or at high isostatic pressure (HIP). Several types of defects were observed by electron microscopy. Both un-HIPed and HIPed samples contain a large number of intra-grain Mg(B,O) 2 precipitates coherent with the matrix, with sizes very well suited to act as pinning centers (5 - 100 nm). The HIP process further improves flux pinning by eliminating porosity and generating dislocations. We also present a detailed study of the temperature T, field H and current density J dependence of the normalized time (t) relaxation rate, S=dlnJ/dlnt. At low T, we observe a linear S(T), from which we extract a pinning energy Uc that is weakly T dependent and decreases monotonically with H. The extrapolations to T=0 indicate that the quantum creep rate is small. At higher T, the activation energy U(J) shows the divergent behavior at J -> 0 that characterizes the glassy phases. Results are contrasted with the expectations of various collective creep scenarios to extract information on the characteristics of the pinning centers.

  2. Electric transport measurements on bulk, polycrystalline MgB2 samples prepared at various reaction temperatures

    NASA Astrophysics Data System (ADS)

    Wiederhold, A.; Koblischka, M. R.; Inoue, K.; Muralidhar, M.; Murakami, M.; Hartmann, U.

    2016-03-01

    A series of disk-shaped, bulk MgB2 superconductors (sample diameter up to 4 cm) was prepared in order to improve the performance for superconducting super-magnets. Several samples were fabricated using a solid state reaction in pure Ar atmosphere from 750 to 950oC in order to determine the optimum processing parameters to obtain the highest critical current density as well as large trapped field values. Additional samples were prepared with added silver (up to 10 wt.-%) to the Mg and B powder. Magneto-resistance data and I/V-characteristics were recorded using an Oxford Instruments Teslatron system. From Arrhenius plots, we determine the TAFF pinning potential, U 0. The I/V-characteristics yield detailed information on the current flow through the polycrystalline samples. The current flow is influenced by the presence of pores in the samples. Our analysis of the achieved critical currents together with a thorough microstructure investigation reveals that the samples prepared at temperatures between 775°C and 805°C exhibit the smallest grains and the best connectivity between them, while the samples fabricated at higher reaction temperatures show a reduced connectivity and lower pinning potential. Doping the samples with silver leads to a considerable increase of the pinning potential and hence, the critical current densities.

  3. Energy from true in situ processing of antrim shale: Extraction trials in an explosively fractured site

    NASA Astrophysics Data System (ADS)

    Vanderploeg, M. L.; Peil, C. A.; Kinkel, C. G.; Pihlaja, R. K.; Murdick, D. A.; Frost, J. R.; Lund, M. M.

    1980-08-01

    Three in situ energy extraction trials were conducted at an oil shale site in Michigan. Here the Antrim shale layer occurs between 1200 and 1400 feet underground. The three trials, lasting 7, 60 and 17 days respectively, were conducted in a formation prepared by explosive fracturing. Ignition energy was generated with a methane burner. Some energy in the form of a dilute fuel gas was recovered in each trial but upon ignition drastic decreases in flow communication occurred between injection and production wells. That problem prevented the planned exploration of techniques which would raise the energy value of the production gas. Upon cool down of the formation after each trial, air permeability tests showed inter-well communication levels returning to near preburn levels. Thermal expansion is the most likely cause of the reduced permeability experienced under retorting conditions.

  4. A Computer Program for Processing In Situ Permeable Flow Sensor Data

    1996-04-15

    FLOW4.02 is used to interpret data from In Situ Permeable Flow Sensors which are instruments that directly measure groundwater flow velocity in saturated, unconsolidated geologic formations (Ballard, 1994, 1996: Ballard et al., 1994: Ballard et al., in press). The program accepts as input the electrical resistance measurements from the thermistors incorporated within the flow sensors, converts the resistance data to temperatures and then uses the temperature information to calculate the groundwater flow velocity and associatedmore » uncertainty. The software includes many capabilities for manipulating, graphically displaying and writing to disk the raw resistance data, the temperature data and the calculated flow velocity information. This version is a major revision of a previously copyrighted version (FLOW1.0).« less

  5. Enhancement of Biodiesel Production from Marine Alga, Scenedesmus sp. through In Situ Transesterification Process Associated with Acidic Catalyst

    PubMed Central

    Kim, Ga Vin; Choi, WoonYong; Kang, DoHyung; Lee, ShinYoung; Lee, HyeonYong

    2014-01-01

    The aim of this study was to increase the yield of biodiesel produced by Scenedesmus sp. through in situ transesterification by optimizing various process parameters. Based on the orthogonal matrix analysis for the acidic catalyst, the effects of the factors decreased in the order of reaction temperature (47.5%) > solvent quantity (26.7%) > reaction time (17.5%) > catalyst amount (8.3%). Based on a Taguchi analysis, the effects of the factors decreased in the order of solvent ratio (34.36%) > catalyst (28.62%) > time (19.72%) > temperature (17.32%). The overall biodiesel production appeared to be better using NaOH as an alkaline catalyst rather than using H2SO4 in an acidic process, at 55.07 ± 2.18% (based on lipid weight) versus 48.41 ± 0.21%. However, in considering the purified biodiesel, it was found that the acidic catalyst was approximately 2.5 times more efficient than the alkaline catalyst under the following optimal conditions: temperature of 70°C (level 2), reaction time of 10 hrs (level 2), catalyst amount of 5% (level 3), and biomass to solvent ratio of 1 : 15 (level 2), respectively. These results clearly demonstrated that the acidic solvent, which combined oil extraction with in situ transesterification, was an effective catalyst for the production of high-quantity, high-quality biodiesel from a Scenedesmus sp. PMID:24689039

  6. Enhancement of biodiesel production from marine alga, Scenedesmus sp. through in situ transesterification process associated with acidic catalyst.

    PubMed

    Kim, Ga Vin; Choi, Woonyong; Kang, Dohyung; Lee, Shinyoung; Lee, Hyeonyong

    2014-01-01

    The aim of this study was to increase the yield of biodiesel produced by Scenedesmus sp. through in situ transesterification by optimizing various process parameters. Based on the orthogonal matrix analysis for the acidic catalyst, the effects of the factors decreased in the order of reaction temperature (47.5%) > solvent quantity (26.7%) > reaction time (17.5%) > catalyst amount (8.3%). Based on a Taguchi analysis, the effects of the factors decreased in the order of solvent ratio (34.36%) > catalyst (28.62%) > time (19.72%) > temperature (17.32%). The overall biodiesel production appeared to be better using NaOH as an alkaline catalyst rather than using H2SO4 in an acidic process, at 55.07 ± 2.18% (based on lipid weight) versus 48.41 ± 0.21%. However, in considering the purified biodiesel, it was found that the acidic catalyst was approximately 2.5 times more efficient than the alkaline catalyst under the following optimal conditions: temperature of 70 °C (level 2), reaction time of 10 hrs (level 2), catalyst amount of 5% (level 3), and biomass to solvent ratio of 1 : 15 (level 2), respectively. These results clearly demonstrated that the acidic solvent, which combined oil extraction with in situ transesterification, was an effective catalyst for the production of high-quantity, high-quality biodiesel from a Scenedesmus sp.

  7. Time-resolved photoexcitation of the superconducting two-gap state in MgB2 thin films.

    PubMed

    Xu, Y; Khafizov, M; Satrapinsky, L; Kús, P; Plecenik, A; Sobolewski, Roman

    2003-11-01

    Femtosecond pump-probe studies show that carrier dynamics in MgB2 films is governed by the sub-ps electron-phonon (e-ph) relaxation present at all temperatures, the few-ps e-ph process well pronounced below 70 K, and the sub-ns superconducting relaxation below T(c). The amplitude of the superconducting component versus temperature follows the superposition of the isotropic dirty gap and the three-dimensional pi gap dependences, closing at two different T(c) values. The time constant of the few-ps relaxation exhibits a double divergence at temperatures corresponding to the T(c)'s of the two gaps.

  8. Definitive experimental evidence for two-band superconductivity in MgB2.

    PubMed

    Tsuda, S; Yokoya, T; Takano, Y; Kito, H; Matsushita, A; Yin, F; Itoh, J; Harima, H; Shin, S

    2003-09-19

    The superconducting-gap of MgB2 has been studied by high-resolution angle-resolved photoemission spectroscopy. The results show that superconducting gaps with values of 5.5 and 2.2 meV open on the sigma band and the pi band, respectively, but both the gaps close at the bulk transition temperature, providing a definitive experimental evidence for the two-band superconductivity with strong interband pairing interaction in MgB2. The experiments validate the role of k-dependent electron-phonon coupling as the origin of multiple-gap superconductivity as well as the high transition temperature of MgB2.

  9. Coherent phonon decay and the boron isotope effect for MgB2.

    PubMed

    Alarco, Jose A; Talbot, Peter C; Mackinnon, Ian D R

    2014-12-14

    Ab initio DFT calculations for the phonon dispersion (PD) and the phonon density of states (PDOS) of the two isotopic forms ((10)B and (11)B) of MgB2 demonstrate that use of a reduced symmetry super-lattice provides an improved approximation to the dynamical, phonon-distorted P6/mmm crystal structure. Construction of phonon frequency plots using calculated values for these isotopic forms gives linear trends with integer multiples of a base frequency that change in slope in a manner consistent with the isotope effect (IE). Spectral parameters inferred from this method are similar to that determined experimentally for the pure isotopic forms of MgB2. Comparison with AlB2 demonstrates that a coherent phonon decay down to acoustic modes is not possible for this metal. Coherent acoustic phonon decay may be an important contributor to superconductivity for MgB2.

  10. Magnetization and electric transport properties of single-crystal MgB2 nanowires.

    PubMed

    Wu, Cen-Shawn; Chang, Yu-Cheng; Chen, Weimeng; Chen, Chinping; Feng, Qingrong

    2012-11-23

    High quality single-crystal magnesium diboride (MgB(2)) nanowires with lengths exceeding 10 μm were successfully synthesized by hybrid physical chemical vapor deposition. The magnetization and electrical transport properties of single-crystal MgB(2) nanowires (NWs) were measured. The superconducting transition temperature of the NWs was 37 K, as confirmed by magnetization measurements. The disordered behavior of the nanowires was observed by four-terminal current-voltage characteristic measurements of an individual NW from T = 10 to 300 K. The temperature-dependent resistivity curves for seven NWs collapsed into a universal curve described by the variable range hopping model, showing intrinsic nonmetallic transport properties. This implies that the granular superconducting defect states are critical to the superconductivity of the individual MgB(2) NWs.

  11. Three-dimensional MgB2-type superconductivity in hole-doped diamond.

    PubMed

    Boeri, Lilia; Kortus, Jens; Andersen, O K

    2004-12-01

    We substantiate by numerical and analytical calculations that the recently discovered superconductivity below 4 K in 3% boron-doped diamond is caused by electron-phonon coupling of the same type as in MgB2, albeit in three dimensions. Holes at the top of the zone-centered, degenerate sigma-bonding valence-band couple strongly to the optical bond-stretching modes. The increase from two to three dimensions reduces the mode softening crucial for T(c) reaching 40 K in MgB2. Even if diamond had the same bare coupling constant as MgB2, which could be achieved with 10% doping, T(c) would be only 25 K. Superconductivity above 1 K in Si (Ge) requires hole doping beyond 5% (10%).

  12. Anisotropy of superconducting MgB2 as seen in electron spin resonance and magnetization data.

    PubMed

    Simon, F; Jánossy, A; Fehér, T; Murányi, F; Garaj, S; Forró, L; Petrovic, C; Bud'ko, S L; Lapertot, G; Kogan, V G; Canfield, P C

    2001-07-23

    We observed the conduction electron spin resonance (CESR) in fine powders of MgB2 both in the superconducting and normal states. The Pauli susceptibility is chi(s) = 2.0 x 10(-5) emu/mole in the temperature range of 450 to 600 K. The spin relaxation rate has an anomalous temperature dependence. The CESR measured below T(c) at several frequencies suggests that MgB2 is a strongly anisotropic superconductor with the upper critical field, H(c2), ranging between 2 and 16 T. The high-field reversible magnetization data of a randomly oriented powder sample are well described assuming that MgB2 is an anisotropic superconductor with H(ab)(c2)/H(c)(c2) approximately 6-9.

  13. Physics Among Lightweights: Boride Superconductors (Superconductivity in MgB2)

    SciTech Connect

    Canfield, Paul C.

    2001-06-13

    Recently there has been a great deal of excitement about the intermetallic superconductor MgB2. MgB2 has a superconducting transition temperature Tc {approx} 40 K, can be synthesized as single phase powders and wire segments, has a remarkably low normal state resistivity, and manifests a promising critical current density in the superconducting state. In this colloquium I will review recent discoveries associated with intermetallic borides and try to show how MgB2 fits into the basic gestalt of intermetallic compounds. In addition I will try to explain why anybody should care about this and why some physicists find the topic of novel states in intermetallic compounds to be an extremely interesting research topic.

  14. Comparison between nano-diamond and carbon nanotube doping effects on critical current density and flux pinning in MgB2

    NASA Astrophysics Data System (ADS)

    Cheng, C. H.; Yang, Y.; Munroe, P.; Zhao, Y.

    2007-03-01

    Doping effects of nano-diamond and carbon nanotubes (CNTs) on critical current density of bulk MgB2 have been studied. CNTs are found prone to be doped into the MgB2 lattice whereas nano-diamond tends to form second-phase inclusions in the MgB2 matrix, leading to a more significant improvement of Jc(H) by doping by nano-diamond than by CNTs in MgB2. TEM reveals tightly packed MgB2 nanograins (50-100 nm) with a dense distribution of diamond nanoparticles (10-20 nm) inside MgB2 grains in nano-diamond-doped samples. Such a unique microstructure leads to a flux pinning behaviour different from that in CNTs-doped MgB2.

  15. Sensing, Control, and In Situ Measurement of Coating Properties: An Integrated Approach Toward Establishing Process-Property Correlations

    NASA Astrophysics Data System (ADS)

    Sampath, S.; Srinivasan, V.; Valarezo, A.; Vaidya, A.; Streibl, T.

    2009-06-01

    Over the last decade there has been an explosion in terms of available tools for sensing the particle spray stream in thermal spray processes. This has led to considerable enhancement in our understanding of process reproducibility and reliability. Despite these advances, the linkage to coating properties has continued to be an enigma. This is partially due to the complex nature of the build-up process and the associated issues with measuring properties of these complex coatings. In this paper, we identify critical issues in processing-structure-property relations particularly with respect to the linkage to particle properties. Our goal is to demonstrate an integrated strategy, one that combines particle state sensing, with process mapping and extracting coating properties in situ through the development of robust and advanced curvature-based techniques. These techniques allow estimation of coating modulus, residual stress and, non-linear response of thermal sprayed ceramic coatings all within minutes of the deposition process. Finally, the integrated strategy examines the role of process maps for control of the spray stream as well as tailoring properties of thermal spray coatings. Examples of such studies for yttria-stabilized zirconia thermal barrier coatings are discussed.

  16. Electronic structure of scandium-doped MgB2

    NASA Astrophysics Data System (ADS)

    de La Peña, Omar; Agrestini, Stefano

    2005-03-01

    Recently has been reported the synthesis of a new superconducting alloy based on MgB2, where Mg is partially substituted with Sc. In order to analyze the effect of Sc doping on the structural and superconducting properties of Mg1-xScxB2, we have performed a detailed study of the electronic structure for this new diboride. The calculations have been done using the first-principles LAPW method, within the supercell approach for modeling the doping. In this work we report results for the electronic band structure, Fermi surface, and density of states. The effect of the Sc-d orbitals on the structural and electronic properties of Mg1-xScxB2 is analyzed. Increasing the Sc concentration (x) the σ-band is gradually filled, because Sc have one valence electron more than Mg. Interestingly, the analysis of the band structure shows that even for ScB2 the top of the σ-band remain above the Fermi level, nevertheless the σ-band presents high dispersion and has an important contribution of d states. In this way, in addition to the band filling effect, Sc doping gradually reduces the two-dimensional character of the σ- band in Mg1-xScxB2 as a result of increasing the sp(B)-d(Sc) hybridization. This research was partially supported by Consejo Nacional de Ciencia y Tecnolog'ia (CONACYT, M'exico) under Grant. No. 43830-F

  17. Lightweight MgB2 superconducting 10 MW wind generator

    NASA Astrophysics Data System (ADS)

    Marino, I.; Pujana, A.; Sarmiento, G.; Sanz, S.; Merino, J. M.; Tropeano, M.; Sun, J.; Canosa, T.

    2016-02-01

    The offshore wind market demands a higher power rate and more reliable turbines in order to optimize capital and operational costs. The state-of-the-art shows that both geared and direct-drive conventional generators are difficult to scale up to 10 MW and beyond due to their huge size and weight. Superconducting direct-drive wind generators are considered a promising solution to achieve lighter weight machines. This work presents an innovative 10 MW 8.1 rpm direct-drive partial superconducting generator using MgB2 wire for the field coils. It has a warm iron rotor configuration with the superconducting coils working at 20 K while the rotor core and the armature are at ambient temperature. A cooling system based on cryocoolers installed in the rotor extracts the heat from the superconducting coils by conduction. The generator's main parameters are compared against a permanent magnet reference machine, showing a significant weight and size reduction. The 10 MW superconducting generator concept will be experimentally validated with a small-scale magnetic machine, which has innovative components such as superconducting coils, modular cryostats and cooling systems, and will have similar size and characteristics as the 10 MW generator.

  18. Suppression of superconductivity in epitaxial MgB2 ultrathin films

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Wang, Yue; Wang, Da; Zhang, Yan; Liu, Zheng-Hao; Feng, Qing-Rong; Gan, Zi-Zhao

    2013-07-01

    MgB2 ultrathin films have potential to make sensitive superconducting devices such as superconducting single-photon detectors working at relatively high temperatures. We have grown epitaxial MgB2 films in thicknesses ranging from about 40 nm to 6 nm by using the hybrid physical-chemical vapor deposition method and performed electrical transport measurements to study the thickness dependence of the superconducting critical temperature Tc. With reducing film thickness d, although a weak depression of the Tc has been observed, which could be attributed to an increase of disorder (interband impurity scattering) in the film, the Tc retains close to the bulk value of MgB2 (39 K), being about 35 K in the film of 6 nm thick. We show that this result, beneficial to the application of MgB2 ultrathin films and in accordance with recent theoretical calculations, is in contrast to previous findings in MgB2 films prepared by other methods such as co-evaporation and molecular-beam epitaxy, where a severe Tc suppression has been observed with Tc about one third of the bulk value in films of ˜5 nm thick. We discuss this apparent discrepancy in experiments and suggest that, towards the ultrathin limit, the different degrees of Tc suppression displayed in currently obtained MgB2 films by various techniques may arise from the different levels of disorder present in the film or different extents of proximity effect at the film surface or film-substrate interface.

  19. A whole biodiesel conversion process combining isolation, cultivation and in situ supercritical methanol transesterification of native microalgae.

    PubMed

    Jazzar, Souhir; Quesada-Medina, Joaquín; Olivares-Carrillo, Pilar; Marzouki, Mohamed Néjib; Acién-Fernández, Francisco Gabriel; Fernández-Sevilla, José María; Molina-Grima, Emilio; Smaali, Issam

    2015-08-01

    A coupled process combining microalgae production with direct supercritical biodiesel conversion using a reduced number of operating steps is proposed in this work. Two newly isolated native microalgae strains, identified as Chlorella sp. and Nannochloris sp., were cultivated in both batch and continuous modes. Maximum productivities were achieved during continuous cultures with 318mg/lday and 256mg/lday for Chlorella sp. and Nannochloris sp., respectively. Microalgae were further characterized by determining their photosynthetic performance and nutrient removal efficiency. Biodiesel was produced by catalyst-free in situ supercritical methanol transesterification of wet unwashed algal biomass (75wt.% of moisture). Maximum biodiesel yields of 45.62wt.% and 21.79wt.% were reached for Chlorella sp. and Nannochloris sp., respectively. The analysis of polyunsaturated fatty acids of Chlorella sp. showed a decrease in their proportion when comparing conventional and supercritical transesterification processes (from 37.4% to 13.9%, respectively), thus improving the quality of the biodiesel.

  20. In situ monitoring of discharge/charge processes in Li-O2 batteries by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Landa-Medrano, Imanol; Ruiz de Larramendi, Idoia; Ortiz-Vitoriano, Nagore; Pinedo, Ricardo; Ignacio Ruiz de Larramendi, José; Rojo, Teófilo

    2014-03-01

    Gaining insight into the reaction mechanisms underway during charge and discharge in Li-air batteries is essential to allow the target development of improved power and performance devices. This work reports the in situ monitoring of Li-air cells by electrochemical impedance spectroscopy and, for the first time, the development of an electrochemical model allowing the identification and attribution of the processes involved. The voltage at which each reaction product forms has been identified, including Li2O2 or Li2CO3 during discharge, together with the delithiation of the outer part of Li2O2 and oxidation reactions and electrolyte decomposition. The developed model can be used as a valuable tool for the optimisation of composition and structure of the air electrode through the investigation of the resistance associated with each process.

  1. Experimental hybrid power transmission line with liquid hydrogen and MgB2-based superconducting cable

    NASA Astrophysics Data System (ADS)

    Kostyuk, V. V.; Antyukhov, I. V.; Blagov, E. V.; Vysotsky, V. S.; Katorgin, B. I.; Nosov, A. A.; Fetisov, S. S.; Firsov, V. P.

    2012-03-01

    Results of developing and testing an experimental hybrid power transmission line with liquid hydrogen and superconducting power (SCP) cable based on magnesium diboride (MgB2) are presented. Critical currents of the MgB2 based prototype SCP cable have been determined for the first time at the forced flow of liquid hydrogen in a temperature interval of 20-26 K. Various regimes of SCP cable cryostatting with both subcooled saturated liquid hydrogen have been tested in a broad range of supply rates (7-220 g/s) and pressures (0.15-0.4 MPa).

  2. Low-Temperature Synthesis of Superconducting Nanocrystalline MgB 2

    DOE PAGES

    Lu, Jun; Xiao, Zhili; Lin, Qiyin; Claus, Helmut; Fang, Zhigang Zak

    2010-01-01

    Magnesium diboride (MgB 2 ) is considered a promising material for practical application in superconducting devices, with a transition temperature near 40 K. In the present paper, nanocrystalline MgB 2 with an average particle size of approximately 70 nm is synthesized by reacting LiBH 4 with MgH 2 at temperatures as low as 450 ° C. This synthesis approach successfully bypasses the usage of either elemental boron or toxic diborane gas. The superconductivity of the nanostructures is confirmed by magnetization measurements, showing a superconducting critical temperature of 38.7 K.

  3. The preliminary study of the quench protection of an MgB2

    NASA Astrophysics Data System (ADS)

    Juster, F. P.; Berriaud, C.; Bonelli, A.; Pasquet, R.; Przybilski, H.; Schild, T.; Scola, L.

    2014-01-01

    In the framework of general studies currently carried out at CEA/Saclay in collaboration with Sigmaphi Company on dry MgB2 magnet operating at 10 K and medium range field, 1 T up to 4 T., we plan to build a prototype-coil with a commercial MgB2 wire. This coil, the nominal axial magnetic field of which is 1 tesla, will be placed in a 3 teslas background field generated by a classical NbTi coil. This paper deals with the preliminary quench protection studies including stability and quench propagation modeling.

  4. Isotope Effect on Electron-Phonon Coupling in Multiband Superconductor MgB2

    NASA Astrophysics Data System (ADS)

    Mou, Daixiang; Taufour, Valentin; Wu, Yun; Huang, Lunan; Bud'Ko, Serguei; Canfield, Paul; Kaminski, Adam

    We systematically investigate the isotope effect of electron-phonon coupling in multi-band superconductor MgB2 by laser based Angle Resolved Photoemission Spectroscopy. The kink structure around 70 meV on two σ bands, which is caused by electron coupling to E2 g phonon mode, is shifted to higher binding energy in Mg10B2 than that in Mg11B2. The measured shifting energy of 3.5 meV is consistent with theoretical calculation based on harmonic phonon in MgB2. Our temperature dependent measurement also indicates the isotope effect of kink structure is not dependent on superconducting transition.

  5. MgB2 ultrathin films fabricated by hybrid physical chemical vapor deposition and ion milling

    NASA Astrophysics Data System (ADS)

    Acharya, Narendra; Wolak, Matthäus A.; Tan, Teng; Lee, Namhoon; Lang, Andrew C.; Taheri, Mitra; Cunnane, Dan; Karasik, Boris. S.; Xi, X. X.

    2016-08-01

    In this letter, we report on the structural and transport measurements of ultrathin MgB2 films grown by hybrid physical-chemical vapor deposition followed by low incident angle Ar ion milling. The ultrathin films as thin as 1.8 nm, or 6 unit cells, exhibit excellent superconducting properties such as high critical temperature (Tc) and high critical current density (Jc). The results show the great potential of these ultrathin films for superconducting devices and present a possibility to explore superconductivity in MgB2 at the 2D limit.

  6. Observation of interband pairing interaction in a two-band superconductor: MgB2.

    PubMed

    Geerk, J; Schneider, R; Linker, G; Zaitsev, A G; Heid, R; Bohnen, K-P; v Löhneysen, H

    2005-06-10

    The recently discovered anisotropic superconductor MgB2 is the first of its kind showing the intriguing properties of two-band superconductivity. By tunneling experiments using thin film tunnel junctions, electron-coupled phonon spectra were determined showing that superconductivity in MgB2 is phonon mediated. In a further analysis, which involves first principles calculations, the strongest feature in these spectra could be traced back to the key quantity of two-band superconductivity, the interband pairing interaction. For the phonons, this interaction turns out quite selective. It involves mainly low-energy optical phonon modes, where the boron atoms move perpendicular to the boron planes.

  7. Pair-breaking and superconducting state recovery dynamics in MgB2.

    PubMed

    Demsar, J; Averitt, R D; Taylor, A J; Kabanov, V V; Kang, W N; Kim, H J; Choi, E M; Lee, S I

    2003-12-31

    We present studies of the photoexcited quasiparticle dynamics in MgB2 where, using femtosecond optical techniques, Cooper pair-breaking dynamics (PBD) have been temporally resolved for the first time. The PBD are strongly temperature and photoexcitation intensity dependent. Analysis of the PBD using the Rothwarf-Taylor equations suggests that the anomalous PBD arises from the fact that in MgB2 photoexcitation is initially followed by energy relaxation to high frequency phonons instead of, as commonly assumed, e-e thermalization. Furthermore, the bare quasiparticle recombination rate and the probability for pair breaking by phonons have been determined.

  8. Magnetic vortex flux pinning in silicon-oil-doped MgB2

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Ik; Ghorbani, S. R.

    2010-12-01

    The field dependence of the critical current density, jc (B), of MgB2 doped with 10 wt.% of a liquid precursor, silicon oil, was measured. The obtained jc (B) was enhanced compared with the value of pure MgB2. The temperature dependence of the crossover field, Bsb(T), from the region of a single vortex to the region of small vortex bundle pinning shows that δl pinning, which is associated with mean-free-path fluctuations of the charge carriers, is dominant in this superconductor.

  9. Electrochemical synthesis of superconductive MgB 2 from molten salts

    NASA Astrophysics Data System (ADS)

    Yoshii, Kenji; Abe, Hideki

    2003-05-01

    We have found that superconductive MgB2 can be electrochemically synthesized from molten salts. The electrolysis was performed in an Ar flow at 600 °C on fused mixtures composed of MgCl2, MgB2O4, Na2B2O4 and alkali halides such as KCl, NaCl, and LiCl. Superconductivity was observed for a wide variety of electrolytes. It was also found that the magnetic and electrical transport properties are the most improved for samples prepared from MgCl2-NaCl-KCl-MgB2O4 electrolytes.

  10. Calibrating IR cameras for in-situ temperature measurement during the electron beam melt processing of Inconel 718 and Ti-Al6-V4

    NASA Astrophysics Data System (ADS)

    Dinwiddie, R. B.; Kirka, M. M.; Lloyd, P. D.; Dehoff, R. R.; Lowe, L. E.; Marlow, G. S.

    2016-05-01

    High performance mid-wave infrared (IR) cameras are used for in-situ electron beam melt process monitoring and temperature measurements. Since standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption, two techniques for temperature calibrations are compared. In-situ measurement of emittance will also be discussed. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  11. Crosshole shear-wave seismic monitoring of an in situ air stripping waste remediation process

    SciTech Connect

    Elbring, G.J.

    1992-02-01

    Crosshole shear-wave seismic surveys have been used to monitor the distribution of injected air in the subsurface during an in situ air stripping waste remediation project at the Savannah River site in South Carolina. To remove the contaminant, in this case TCE's from a leaking sewer line, two horizontal wells were drilled at depths of 20 m and 52 m. Air was pumped into the lower well and a vacuum was applied to the upper well to extract the injected air. As the air passed through the subsurface, TCE's were dissolved into the gas and brought out the extraction well. Monitoring of the air injection by crosshole shear wave seismics is feasible due to the changes in soil saturation during injection resulting in a corresponding change in seismic velocities. Using a downhole shear-wave source and clamped downhole receiver, two sets of shear-wave data were taken. The first data were taken before the start of air injection, and the second taken during. The difference in travel times between the two data sets were tomographically inverted to obtain velocity differences. Velocity changes ranging up to 3% were mapped corresponding to saturation changes up to 24%. The distribution of these changes shows a desaturation around the position of the injection well with a plume extending in the direction of the extraction well. Layers with higher clay content show distinctively less change in saturation than the regions with higher sand content.

  12. Crosshole shear-wave seismic monitoring of an in situ air stripping waste remediation process

    SciTech Connect

    Elbring, G.J.

    1992-02-01

    Crosshole shear-wave seismic surveys have been used to monitor the distribution of injected air in the subsurface during an in situ air stripping waste remediation project at the Savannah River site in South Carolina. To remove the contaminant, in this case TCE`s from a leaking sewer line, two horizontal wells were drilled at depths of 20 m and 52 m. Air was pumped into the lower well and a vacuum was applied to the upper well to extract the injected air. As the air passed through the subsurface, TCE`s were dissolved into the gas and brought out the extraction well. Monitoring of the air injection by crosshole shear wave seismics is feasible due to the changes in soil saturation during injection resulting in a corresponding change in seismic velocities. Using a downhole shear-wave source and clamped downhole receiver, two sets of shear-wave data were taken. The first data were taken before the start of air injection, and the second taken during. The difference in travel times between the two data sets were tomographically inverted to obtain velocity differences. Velocity changes ranging up to 3% were mapped corresponding to saturation changes up to 24%. The distribution of these changes shows a desaturation around the position of the injection well with a plume extending in the direction of the extraction well. Layers with higher clay content show distinctively less change in saturation than the regions with higher sand content.

  13. Process Analysis Of Thin Film Deposition With An In Situ Ellipsometer

    NASA Astrophysics Data System (ADS)

    Savrda, Steven; Himel, Marc D.; Guenther, Karl H.; Urban, Frank K.

    1990-01-01

    Thin films deposited in high vacuum by thermal evaporation, electron beam evaporation, and ion assisted deposition are anything but smooth, homogeneous, stratified media with plane parallel boundaries as assumed in thin film design and theory. In particular, the porosity brought about by the columnar microstructure of these films has been a problem ever since their first use. The refractive index may change upon exposure to ambient atmosphere, as a result of H2O adsorption. In-situ rapid scanning spectrophotometers and ellipsometers have helped various researchers to determine the degree of index change and the packing density of the films. Low voltage reactive ion plating is a rather novel deposition technique which produces thin films with packing densities of unity and higher. The dense, vitreous or polycrystalline microstructure, which pre-vents the films from adsorbing water upon exposure to air, yields films with bulk-like optical properties that are constant in time. However, there are problems with increased absorption particularly with ion plated TiO2 and SiO2 multilayer thin-film stacks. Continuous measurements of n and k during deposition need to be studied in order to determine the location of the increased absorption. Engineering aspects of mounting a Rudolph Research ellipsometer on a Balzers BAP 800 vacuum system will also be discussed.

  14. Stability investigations of zinc and cobalt precipitates immobilized by in situ bioprecipitation (ISBP) process.

    PubMed

    Satyawali, Yamini; Schols, Edo; Van Roy, Sandra; Dejonghe, Winnie; Diels, Ludo; Vanbroekhoven, Karolien

    2010-09-15

    In situ bioprecipitation (ISBP), which involves immobilizing the metals as precipitates (mainly sulphides) in the solid phase, is an effective method of metal removal from contaminated groundwater. This study investigated the stability of metal precipitates formed after ISBP in two different solid-liquid matrices (artificial and natural). The artificial matrix consisted of sand, Zn (200 mg L(-1)), artificial groundwater and a carbon source (electron donor). Here the stability of the Zn precipitates was evaluated by manipulation of redox and pH. The natural system matrices included aquifer material and groundwater samples collected from three different metal (Zn and Co) contaminated sites and different carbon sources were provided as electron donors. In the natural matrices, metal precipitates stability was assessed by changing aquifer redox conditions, sequential extraction, and BIOMET assay. The results indicated that, in the artificial matrix, redox manipulation did not impact the Zn precipitates. However the sequential pH change proved detrimental, releasing 58% of the precipitated Zn back into liquid phase. In natural matrices, the applied carbon source largely affected the stability of metal precipitates. Elemental analysis performed on the precipitates formed in natural matrix showed that the main elements of the precipitates were sulphur with Zn and Co.

  15. Vegetative evaluation of procedures used to treat aqueous effluents derived from in situ fossil fuel processing

    SciTech Connect

    Skinner, Q.D.; Carson, J.M.

    1985-01-01

    The effectiveness of synthetic fuel waste water treatment in removing compounds toxic to a rangeland grass was evaluated. Treated and untreated tar sand and oil shale in situ produced waste water were applied to bluebunch wheatgrass (Agropyron spicatum) and phytotoxic effects were observed. Different waste water concentrations (volume/volume dilutions with distilled water) were tested to help determine a full range of plant response to these waste waters. Test waters plus nutrient solution were applied daily to seedlings grown in perilite or soil for ten weeks. Plants were harvested, dried, weighed and analyzed for treatment differences using leaf area; leaf, stem, root, shoot, and total weight production; root to shoot dry weight ratios; and survival. Results indicate treated and untreated tar sand waste waters are toxic but not lethal to bluebunch wheatgrass at high concentrations. Low concentrations of these waters stimulate plant growth. All tested concentrations of treated and untreated oil shale retort waste water were toxic and lethal to bluebunch wheatgrass. 46 references, 2 figures, 10 tables.

  16. Energy from true in situ processing of Antrim Shale: extraction trials in an explosively fractured site

    SciTech Connect

    VanDerPloeg, M.L.; Peil, C.A.; Kinkel, C.G.; Pihlaja, R.K.; Murdick, D.A.; Frost, J.R.; Lund, M.M.

    1980-08-01

    Three in situ energy extraction trials were conducted at The Dow Chemical Company's oil shale site, in Michigan's Sanilac County, near the town of Peck. Here the Antrim shale layer occurs between 1200 and 1400 feet underground. The trials began on October 14, 1979, and ended on April 1, 1980. The three trials, lasting 7, 60 and 17 days respectively, were conducted in a formation prepared by explosive fracturing. Ignition energy was generated with a methane burner. Some energy in the form of a dilute fuel gas (5 to 50 btu/scf) was recovered in each trial but upon ignition drastic decreases in flow communication occurred between injection and production wells. That problem prevented the planned exploration of techniques which would raise the energy value of the production gas. Upon cool down of the formation after each trial, air permeability tests showed inter-well communication levels returning to near preburn levels. Thermal expansion is the most likely cause of the reduced permeability experienced under retorting conditions.

  17. In Situ Monitoring of Plasma Spraying Process by Laser Acoustic Emission Method

    NASA Astrophysics Data System (ADS)

    Ito, Kaita; Enoki, Manabu; Watanabe, Makoto; Kuroda, Seiji

    Estimation of microfractures in ceramic coating layer during plasma spraying process is critical for its reliability. Acoustic emission (AE) method enables in-process monitoring of such microfractures. Laser AE method was adopted to realize the monitoring of plasma spraying process by non-contact detection of AE with laser interferometer. Also a high performance method for noise reduction of laser AE waveform was investigated. In this new method, laser AE signal was continuously sampled and transformed into spectrogram by time-frequency analysis to cut out noise component effectively. After this noise reduction process, inverse transform was applied to obtain a clear AE signals in time domain. Whole these processes can be done in real time. The effectiveness of this method was confirmed by a detection test of simulated AE and successfully applied to the monitoring of plasma spraying process. Two types of AE events with different duration time range were found and the sources of these AE were presumed.

  18. Antibacterial and hemolysis activity of polypyrrole nanotubes decorated with silver nanoparticles by an in-situ reduction process.

    PubMed

    Upadhyay, J; Kumar, A; Gogoi, B; Buragohain, A K

    2015-09-01

    Polypyrrole nanotube-silver nanoparticle nanocomposites (PPy-NTs:Ag-NPs) have been synthesized by in-situ reduction of silver nitrate (AgNO3) to suppress the agglomeration of Ag-NPs. The morphology and chemical structure of the nanocomposites have been studied by HRTEM, SEM, XRD, FTIR and UV-vis spectroscopy. The average diameter of the polypyrrole nanotubes (PPy-NTs) is measured to be 130.59±5.5 nm with their length in the micrometer range, while the silver nanoparticles (Ag-NPs) exhibit spherical shape with an average diameter of 23.12±3.23 nm. In-vitro blood compatibility of the nanocomposites has been carried out via hemolysis assay. Antimicrobial activity of the nanocomposites has been investigated with Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The results depict that the hemolysis and antimicrobial activities of the nanocomposites increase with increasing Ag-NP concentration that can be controlled by the AgNO3 precursor concentration in the in-situ process.

  19. In Situ Study on Current Density Distribution and Its Effect on Interfacial Reaction in a Soldering Process

    NASA Astrophysics Data System (ADS)

    Qu, Lin; Zhao, Ning; Ma, Haitao; Zhao, Huijing; Huang, Mingliang

    2015-01-01

    The interfacial reaction in Cu/Sn/Cu solder joint during liquid-solid eletromigration (EM) was in situ studied using synchrotron radiation real-time imaging technology. The current density distribution in the solder joint was analyzed with the finite element method (FEM). The relationships among solder shape, current density distribution, Cu dissolution, and the formation and dissolution of interfacial intermetallic compound (IMC) were revealed. The current promoted dissolution of the cathode IMC and growth of the anode IMC and suppressed the dissolution of anode Cu. The change of interfacial IMC had little effect on the current density distribution; however, the dissolution of cathode Cu, which changed the solder shape, had a significant effect on the current density distribution. The dissolution of cathode Cu under forward current and cathode IMC under reverse current and the growth of anode IMC under forward current was faster where the current density was higher. The synchrotron radiation real-time imaging technology can not only in situ observe the change of solder shape, the dissolution and growth behavior of interfacial IMC and the dissolution behavior of substrate in a soldering process but also provide data needed for numerical simulation of current density distribution in a solder joint.

  20. In situ annealing and high-rate silicon epitaxy on porous silicon by mesoplasma process

    NASA Astrophysics Data System (ADS)

    Zhang, Sheng; Lu, Ziyu; Sheng, Jiang; Gao, Pingqi; Yang, Xi; Wu, Sudong; Ye, Jichun; Kambara, Makoto

    2016-05-01

    By a mesoplasma process, a double-layer porous Si is annealed for a few seconds, by which an annealing effect similar to that of a prolonged conventional annealing process is obtained. The basic annealing process is considered to follow the classical sintering theory. However, the surface of the annealed porous Si is rough with large open voids because of H etching. The epitaxial Si films deposited on such a rough surface at a rate of 350 nm/s show a smooth surface with a low defect density compared with those deposited on a polished Si wafer, which clearly demonstrates the advantages of the cluster-assisted mesoplasma process.

  1. Hydrochemical processes in lowland rivers: insights from in situ, high-resolution monitoring

    NASA Astrophysics Data System (ADS)

    Wade, A. J.; Palmer-Felgate, E. J.; Halliday, S. J.; Skeffington, R. A.; Loewenthal, M.; Jarvie, H. P.; Bowes, M. J.; Greenway, G. M.; Haswell, S. J.; Bell, I. M.; Joly, E.; Fallatah, A.; Neal, C.; Williams, R. J.; Gozzard, E.; Newman, J. R.

    2012-11-01

    This paper introduces new insights into the hydrochemical functioning of lowland river systems using field-based spectrophotometric and electrode technologies. The streamwater concentrations of nitrogen species and phosphorus fractions were measured at hourly intervals on a continuous basis at two contrasting sites on tributaries of the River Thames - one draining a rural catchment, the River Enborne, and one draining a more urban system, The Cut. The measurements complement those from an existing network of multi-parameter water quality sondes maintained across the Thames catchment and weekly monitoring based on grab samples. The results of the sub-daily monitoring show that streamwater phosphorus concentrations display highly complex dynamics under storm conditions dependent on the antecedent catchment wetness, and that diurnal phosphorus and nitrogen cycles occur under low flow conditions. The diurnal patterns highlight the dominance of sewage inputs in controlling the streamwater phosphorus and nitrogen concentrations at low flows, even at a distance of 7 km from the nearest sewage treatment works in the rural River Enborne. The time of sample collection is important when judging water quality against ecological thresholds or standards. An exhaustion of the supply of phosphorus from diffuse and multiple septic tank sources during storm events was evident and load estimation was not improved by sub-daily monitoring beyond that achieved by daily sampling because of the eventual reduction in the phosphorus mass entering the stream during events. The results highlight the utility of sub-daily water quality measurements and the discussion considers the practicalities and challenges of in situ, sub-daily monitoring.

  2. DEMONSTRATION BULLETIN: IN-SITU THERMAL OXIDATION PROCESS - HRUBETZ ENVIRONMENTAL SERVICES

    EPA Science Inventory

    The HRUBOUT process is a thermal, treatment process designed to remove VOCs and semi-VOCs from contaminated soils. Heated air is injected into the soil below the contamination zone, evaporating soil moisture and removing volatile and semivolatile hydrocarbons. As the water evapor...

  3. Estimation of hysteretic losses for MgB2 tapes under the operating conditions of a generator

    NASA Astrophysics Data System (ADS)

    Vargas-Llanos, Carlos Roberto; Zermeño, Víctor M. R.; Sanz, Santiago; Trillaud, Frederic; Grilli, Francesco

    2016-03-01

    Hysteretic losses in the MgB2 wound superconducting coils of a 550 kW synchronous hybrid scaled generator were estimated as part of the European project SUPRAPOWER led by the Spanish Fundación Tecnalia Research & Innovation. Particular interest was given to the losses caused by the magnetic flux ripples in the rotor coils originating from the conventional stator during nominal operation. To compute these losses, a 2D finite element analysis was conducted and Maxwell’s equations written in the H-formulation were solved considering the nonlinear material properties of the conductor materials. The modeled tapes are made of multiple MgB2 filaments embedded in a Ni matrix and soldered to a high purity copper strip and insulated with Dacron braid. Three geometrical models of single tape cross sections of decreasing complexity were studied: (1) the first model reproduced closely the actual cross section obtained from tape micrographs. (2) The second model was obtained from the computed elasto-plastic deformation of a round Ni wire. (3) The third model was based on a simplified cross section with the superconducting filaments bundled in a single elliptical bulky structure. The last geometry allowed the validation of the modeling technique by comparing numerical losses with results from well-established analytical expressions. Additionally, the following cases of filament transpositions of the multi-filamentary tape were studied: no transposition, partial and full transposition; thereby improving understanding of the relevance of the tape fabrication process on the magnitude of the determination of ac losses. Finally, choosing the right level of geometrical detail, the following operational regimes of the machine and its impact on individual superconducting tape losses in the rotor were studied: bias-dc current, ramping current under ramping background field and magnetic flux ripples under dc background current and field.

  4. SMV1 virus-induced CRISPR spacer acquisition from the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2.

    PubMed

    Erdmann, Susanne; Shah, Shiraz A; Garrett, Roger A

    2013-12-01

    Organisms of the crenarchaeal order Sulfolobales carry complex CRISPR (clustered regularly interspaced short palindromic repeats) adaptive immune systems. These systems are modular and show extensive structural and functional diversity, especially in their interference complexes. The primary targets are an exceptional range of diverse viruses, many of which propagate stably within cells and follow lytic life cycles without producing cell lysis. These properties are consistent with the difficulty of activating CRISPR spacer uptake in the laboratory, but appear to conflict with the high complexity and diversity of the CRISPR immune systems that are found among the Sulfolobales. In the present article, we re-examine the first successful induction of archaeal spacer acquisition in our laboratory that occurred exclusively for the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2 that was co-infected with the virus SMV1 (Sulfolobus monocaudavirus 1). Although we reaffirm that protospacer selection is essentially a random process with respect to the pMGB1 genome, we identified single spacer sequences specific for each of CRISPR loci C, D and E that, exceptionally, occurred in many sequenced clones. Moreover, the same sequence was reproducibly acquired for a given locus in independent experiments, consistent with it being the first protospacer to be selected. There was also a small protospacer bias (1.6:1) to the antisense strand of protein genes. In addition, new experiments demonstrated that spacer acquisition in the previously inactive CRISPR locus A could be induced on freeze-thawing of the infected cells, suggesting that environmental stress can facilitate activation. Coincidentally with spacer acquisition, a mobile OrfB element was deleted from pMGB1, suggesting that interplay can occur between spacer acquisition and transposition.

  5. SMV1 virus-induced CRISPR spacer acquisition from the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2

    PubMed Central

    Erdmann, Susanne; Shah, Shiraz A.; Garrett, Roger A.

    2013-01-01

    Organisms of the crenarchaeal order Sulfolobales carry complex CRISPR (clustered regularly interspaced short palindromic repeats) adaptive immune systems. These systems are modular and show extensive structural and functional diversity, especially in their interference complexes. The primary targets are an exceptional range of diverse viruses, many of which propagate stably within cells and follow lytic life cycles without producing cell lysis. These properties are consistent with the difficulty of activating CRISPR spacer uptake in the laboratory, but appear to conflict with the high complexity and diversity of the CRISPR immune systems that are found among the Sulfolobales. In the present article, we re-examine the first successful induction of archaeal spacer acquisition in our laboratory that occurred exclusively for the conjugative plasmid pMGB1 in Sulfolobus solfataricus P2 that was co-infected with the virus SMV1 (Sulfolobus monocaudavirus 1). Although we reaffirm that protospacer selection is essentially a random process with respect to the pMGB1 genome, we identified single spacer sequences specific for each of CRISPR loci C, D and E that, exceptionally, occurred in many sequenced clones. Moreover, the same sequence was reproducibly acquired for a given locus in independent experiments, consistent with it being the first protospacer to be selected. There was also a small protospacer bias (1.6:1) to the antisense strand of protein genes. In addition, new experiments demonstrated that spacer acquisition in the previously inactive CRISPR locus A could be induced on freeze–thawing of the infected cells, suggesting that environmental stress can facilitate activation. Coincidentally with spacer acquisition, a mobile OrfB element was deleted from pMGB1, suggesting that interplay can occur between spacer acquisition and transposition. PMID:24256236

  6. In situ visualization of the electrolyte solvent filling process by neutron radiography

    NASA Astrophysics Data System (ADS)

    Knoche, Thomas; Zinth, Veronika; Schulz, Michael; Schnell, Joscha; Gilles, Ralph; Reinhart, Gunther

    2016-11-01

    In the manufacturing of Li-ion battery cells, filling with electrolyte liquid is a crucial step in terms of product quality and cost. To gain insight into the process phenomena, a non-destructive imaging method is presented. It is shown that the spreading of electrolyte liquid within the cell during filling and wetting can be visualized by neutron radiography. The experiment allows for the first time to visualize the soaking behaviour of electrolyte liquid in battery cells. The influence of the process parameters on the wetting behaviour is studied and flow paths of the liquid are identified. The electrolyte intake into the cell stack is discussed with two different analytical approaches. Based on the experimental data, the production process can be optimized, leading to stable cell performance and cost reduction due to faster processes and lower scrap rates.

  7. In situ7Li and 133Cs nuclear magnetic resonance investigations on the role of Cs+ additive in lithium-metal deposition process

    NASA Astrophysics Data System (ADS)

    Hu, Jian Zhi; Zhao, Zhenchao; Hu, Mary Y.; Feng, Ju; Deng, Xuchu; Chen, Xilin; Xu, Wu; Liu, Jun; Zhang, Ji-Guang

    2016-02-01

    Cesium ion (Cs+) has been reported to be an effective electrolyte additive to suppress Li dendrite growth which prevents the application of lithium (Li) metal as an anode for rechargeable Li batteries. In this work, we investigated the effect of Cs+ additive on Li depositions using quantitative in situ7Li and 133Cs nuclear magnetic resonance (NMR) with planar symmetric Li cells. It's found that the addition of Cs+ can significantly enhance both the formation of well aligned Li nanorods and reversibility of the Li electrode. In situ133Cs NMR directly confirms that Cs+ migrates to Li electrode to form a positively charged electrostatic shield during the charging process. Much more electrochemical "active" Li was found in Li films deposited with Cs+ additive, while more electrochemical "dead" and thicker Li rods were identified in Li films deposited without Cs+. Combining the in situ and the previous ex-situ results, a Li deposition model has been proposed to explain these observations.

  8. Processing and Mechanical Properties of NiAl-Based In-Situ Composites. Ph.D. Thesis Final Report

    NASA Technical Reports Server (NTRS)

    Johnson, David Ray

    1994-01-01

    In-situ composites based on the NiAl-Cr eutectic system were successfully produced by containerless processing and evaluated. The NiAl-Cr alloys had a fibrous microstructure while the NiAl-(Cr,Mo) alloys containing 1 at. percent or more molybdenum exhibited a lamellar structure. The NiAl-28Cr-6Mo eutectic displays promising high temperature strength while still maintaining a reasonable room temperature fracture toughness when compared to other NiAl-based materials. The Laves phase NiAlTa was used to strengthen NiAl and very promising creep strengths were found for the directionally solidified NiAl-NiAlTa eutectic. The eutectic composition was found to be near NiAl-15.5Ta (at. percent) and well aligned microstructures were produced at this composition. An off-eutectic composition of NiAl-14.5Ta was also processed, consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of these two phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Polyphase in-situ composites were generated by directional solidification of ternary eutectics. The systems investigated were the Ni-Al-Ta-X (X=Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and both the eutectic composition and temperature were determined. Of these ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr,Al)NiTa-Cr eutectic was intermediate between those of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  9. Adsorptive/photo-catalytic process for naphthalene removal from aqueous media using in-situ nickel doped titanium nanocomposite.

    PubMed

    Sharma, Ajit; Lee, Byeong-Kyu

    2015-05-15

    The present study investigates the synthesis and characterization of in-situ nickel doped titanium nanocomposite (TiO2/NiO) use as an adsorbent and a photo-catalyst for naphthalene removal from aqueous phase. Nickel-titanium nanocomposites were synthesized by using an in-situ process for the nickel doping and further calcined at 600 °C for 6 h to produce the desired TiO2/NiO nanocomposite, which was then characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and UV-Vis analysis before and after naphthalene removal. The removal of naphthalene was explored with effect of pH, time and initial concentration of naphthalene (2-25 mg/L) in the presence of dark and light phases. Naphthalene removal tests were conducted under both batch and continuous flow conditions. A special column without any channeling problem was successfully designed for the removal of naphthalene by continuous flow process in the presence of visible light source. The removal was maximized at pH 6.5. The maximum amount of naphthalene removed by TiO2/NiO(0.1) nanocomposite in the presence of visible light phase was 322.1 mg/g, which was 2.5 times greater than that of the parent TiO2. The removal of naphthalene obtained during the breakthrough analysis was consistent with the batch equilibrium data.

  10. Effect of excess Mg and nano-additives on the superconducting properties of weakly connected bulk MgB2

    NASA Astrophysics Data System (ADS)

    Bhadauria, P. P. S.; Gupta, Anurag; Kishan, Hari; Narlikar, A. V.

    2013-02-01

    Series of ex-situ polycrystalline MgB2 bulk samples, by adding different additives like more of excess Mg (5 wt. %), nanoparticles of Ag (3 wt. %), and SiC (10 wt. %) to a previously optimized composition MgB2 + Mg (5 wt. %), were prepared by solid state synthesis route. Detailed investigations were carried out by XRD, SEM, and thermoelectric power S(T), resistivity ρ(T), and magnetization M(B) at temperatures T = 4.2-300 K and applied fields B = 0-8 T. All the samples typically show low connectivity (i.e., normal state current carrying cross section ˜0.9%-3%). The effect of different additives was different on the critical current density (Jc) of the samples. The Jc, for instance at T = 4.2 K and B = 1 T, varied between 4.8 × 107 and 2.8 × 108 A/m2 for various samples. In comparison to the previously optimized values, the Jc was enhanced by further addition of 5 wt. % Mg and degraded both by nano-SiC and nano-Ag addition. However, many of the other properties of the samples were not much affected. For instance, the samples did not show any change in the superconducting onsets, S(T) and the parallel upper critical field (Bc2|| (T) ˜ 11-13 T at 20 K and 20-21 T at 4.2 K). The Jc(B) dependence also shows similar behavior in all the samples, where the Jc is found to scale as B-1 up to a sample independent crossover field Bcr ˜ 2 T and 1.3 T at T = 4.2 and 20 K, respectively. At higher fields B > Bcr, the Jc(B) curves branch out and decrease rapidly towards zero at a sample dependent characteristic field. We try to understand these results quantitatively in terms of changes in connectivity, pinning, and anisotropy driven percolation. However, all our results and analysis point out that the intra-particle regions stay unaffected and mainly the inter-particle regions get affected by the additives leading to the Jc variation in the weakly connected samples.

  11. In-situ monitoring of Saccharomyces cerevisiae ITV01 bioethanol process using near-infrared spectroscopy NIRS and chemometrics.

    PubMed

    Corro-Herrera, Víctor Abel; Gómez-Rodríguez, Javier; Hayward-Jones, Patricia Margaret; Barradas-Dermitz, Dulce María; Aguilar-Uscanga, María Guadalupe; Gschaedler-Mathis, Anne Christine

    2016-03-01

    The application feasibility of in-situ or in-line monitoring of S. cerevisiae ITV01 alcoholic fermentation process, employing Near-Infrared Spectroscopy (NIRS) and Chemometrics, was investigated. During the process in a bioreactor, in the complex analytical matrix, biomass, glucose, ethanol and glycerol determinations were performed by a transflection fiber optic probe immersed in the culture broth and connected to a Near-Infrared (NIR) process analyzer. The NIR spectra recorded between 800 and 2,200 nm were pretreated using Savitzky-Golay smoothing and second derivative in order to perform a partial least squares regression (PLSR) and generate the calibration models. These calibration models were tested by external validation and then used to predict concentrations in batch alcoholic fermentations. The standard errors of calibration (SEC) for biomass, ethanol, glucose and glycerol were 0.212, 0.287, 0.532, and 0.296 g/L and standard errors of prediction (SEP) were 0.323, 0.369, 0.794, and 0.507 g/L, respectively. Calibration and validation criteria were defined and evaluated in order to generate robust and reliable models for an alcoholic fermentation process matrix. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:510-517, 2016. PMID:26743160

  12. Time resolved in situ X-ray diffraction study of crystallisation processes of large pore nanoporous aluminophosphate materials.

    PubMed

    Simmance, Kerry; van Beek, Wouter; Sankar, Gopinathan

    2015-01-01

    Time resolved high-resolution X-ray powder diffraction was utilized to obtain detailed changes in the crystal structure parameters during the hydrothermal crystallization process of the nanoporous aluminophosphate AlPO-5 (AFI) structure. This in situ study offered not only the influence of metal ions on the onset of crystallization and estimation of the activation energy of the process, but also allowed us to determine in detail the changes in lattice parameters during this process. More importantly the time-resolved study clearly showed the lattice expansion in the divalent metal ions substituted system right from the on-set of crystallization process, compared to the one without any dopant ions, which suggest that an amorphous or poorly crystalline network is formed prior to crystallization that contains the large divalent ions (compared to Al(iii), the substituting element), which is in agreement with the combined XAS/XRD study reported earlier. A mechanism based on this and the earlier study is suggested. PMID:25683746

  13. Converting oil shale to liquid fuels: energy inputs and greenhouse gas emissions of the Shell in situ conversion process.

    PubMed

    Brandt, Adam R

    2008-10-01

    Oil shale is a sedimentary rock that contains kerogen, a fossil organic material. Kerogen can be heated to produce oil and gas (retorted). This has traditionally been a CO2-intensive process. In this paper, the Shell in situ conversion process (ICP), which is a novel method of retorting oil shale in place, is analyzed. The ICP utilizes electricity to heat the underground shale over a period of 2 years. Hydrocarbons are produced using conventional oil production techniques, leaving shale oil coke within the formation. The energy inputs and outputs from the ICP, as applied to oil shales of the Green River formation, are modeled. Using these energy inputs, the greenhouse gas (GHG) emissions from the ICP are calculated and are compared to emissions from conventional petroleum. Energy outputs (as refined liquid fuel) are 1.2-1.6 times greater than the total primary energy inputs to the process. In the absence of capturing CO2 generated from electricity produced to fuel the process, well-to-pump GHG emissions are in the range of 30.6-37.1 grams of carbon equivalent per megajoule of liquid fuel produced. These full-fuel-cycle emissions are 21%-47% larger than those from conventionally produced petroleum-based fuels.

  14. In situ control of industrial processes using laser light scattering and optical rotation

    NASA Astrophysics Data System (ADS)

    Mendoza Sanchez, Patricia Judith; López Echevarria, Daniel; Huerta Ruelas, Jorge Adalberto

    2006-02-01

    We present results of optical measurements in products or processes usually found in industrial processes, which can be used to control them. Laser light scattering was employed during semiconductor epitaxial growth by molecular beam epitaxy. With this technique, it was possible to determine growth rate, roughness and critical temperatures related to substrate degradation. With the same scattering technique, oil degradation as function of temperature was monitored for different automotive lubricants. Clear differences can be studied between monograde and multigrade oils. Optical rotation measurements as function of temperature were performed in apple juice in a pasteurization process like. Average variations related to optical rotation dependence of sugars were measured and monitored during heating and cooling process, finding a reversible behavior. As opposite behavior, sugar-protein solution was measured in a similar heating and cooling process. Final result showed a non-reversible behavior related to protein denaturation. Potential applications are discussed for metal-mechanic, electronic, food, and pharmaceutical industry. Future improvements in optical systems to make them more portable and easily implemented under typical industry conditions are mentioned.

  15. Formation of heterostructure devices in a multichamber processing environment with in-vacuo surface analysis diagnostics and in-situ process monitoring

    NASA Astrophysics Data System (ADS)

    Lucovsky, Gerald; Kim, Sang S.; Fitch, J. T.; Wang, Cheng

    1991-03-01

    This paper addresses issues related to multichamber and in-situ processing of heterostructure electronic devices. We discuss the design and operation of two UHV-compatible multichamber systems one designed for one-inch wafers and a second for three-each wafers. Each of these provides: i) substrate introduction via a load-lock chamber ii) surface preparation by a plasma-assisted surface cleaning process iii) thin film deposition of semiconductors and dielectrics by remote plasma enhanced chemical vapor deposition (remote PECVD) iv) surface analysis by Auger electron spectroscopy (AES) and either reflection high energy or low energy electron diffraction (RHEED or LEED) and v) inter-chamber substrate transfer in a UHV compatible environment (1O8 Torr). These systems have been designed exploit the low temperature ( deposition of electronic-quality thin film dielectrics and semiconductors produced by the remote PECVD process. The combination of remote PECVD film deposition coupled with in-vacuo substrate processing has defined processing windows for the formation of heterojunction devices including: i) gate stacks for crystalline silicon c-Si field effect transistors FET''s ii) amorphous silicon a-Si thin film transistors TFT''s and simple TFT circuits and iii) amorphous and microcrystalline sic-Si silicon p-i-n photovoltaic devices. The effectiveness of single-wafer processing is measured by the ability to produce and to maintain electronic-quality interfaces between the various dielectric and semiconductor films that are utilized in these device structures.

  16. In-Situ Real Time Monitoring and Control of Mold Making and Filling Processes: Final Report

    SciTech Connect

    Mohamed Abdelrahman; Kenneth Currie

    2010-12-22

    This project presents a model for addressing several objectives envisioned by the metal casting industries through the integration of research and educational components. It provides an innovative approach to introduce technologies for real time characterization of sand molds, lost foam patterns and monitoring of the mold filling process. The technology developed will enable better control over the casting process. It is expected to reduce scrap and variance in the casting quality. A strong educational component is integrated into the research plan to utilize increased awareness of the industry professional, the potential benefits of the developed technology, and the potential benefits of cross cutting technologies.

  17. Point pinning centers in SiC doped MgB2 wires after HIP

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Zaleski, A.; Morawski, A.; Cetner, T.; Thong, C. J.; Rindfleisch, M. A.

    2016-08-01

    In this study we show that dominant point pinning mechanisms in SiC doped MgB2 wires can be obtained by annealing in high isostatic pressure. The results indicate that the point pinning centers increase the critical current density in medium and high magnetic fields, but not at low magnetic fields. In addition, our study shows that dominant pinning mechanism changes from point to surface type with increase of magnetic fields. An MgB2 wire heat treated in a high pressure of 1.4 GPa shows a high critical current density of 100 A mm‑2 in 13 T at 4.2 K. Scanning electron microscope studies show that high isostatic pressure increases the density of the MgB2 material, eliminates voids, allows for small Si precipitates and homogeneous distribution of Si precipitates. Transport measurements E - B and E - I show that the MgB2 wires manufactured by Hyper Tech Research did not heat up after transition into a normal state. This is important for applications in coils.

  18. Microstructural and superconducting properties of C6H6 added bulk MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Babaoğlu, Meral G.; Safran, Serap; Çiçek, Özlem; Ağıl, Hasan; Ertekin, Ercan; Hossain, Md. Shahriar A.; Yanmaz, Ekrem; Gencer, Ali

    2012-10-01

    The effect of aromatic hydrocarbon (benzene, C6H6) addition on lattice parameters, microstructure, critical temperature (Tc), critical current density (Jc) of bulk MgB2 has been studied. In this work only 2 mol% C6H6 addition was found to be very effective in increasing the Jc values, while resulting in slight reduction of the Tc. Jc values of 2 mol% C6H6 added MgB2 bulks reached to 1.83×106 A/cm2 at 15 K and 0 T. Microstructural analyses suggest that Jc enhancement is associated with the substitution of carbon with boron and which also results in the smaller MgB2 grain size. The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the Tc by carbon addition. We note that our results show the advantages of C6H6 addition include homogeneous mixing of precursor powders, avoidance of expansive nanoadditives, production of highly reactive C, and significant enhancement in Jc of MgB2, compared to un-doped samples.

  19. Point pinning centers in SiC doped MgB2 wires after HIP

    NASA Astrophysics Data System (ADS)

    Gajda, D.; Zaleski, A.; Morawski, A.; Cetner, T.; Thong, C. J.; Rindfleisch, M. A.

    2016-08-01

    In this study we show that dominant point pinning mechanisms in SiC doped MgB2 wires can be obtained by annealing in high isostatic pressure. The results indicate that the point pinning centers increase the critical current density in medium and high magnetic fields, but not at low magnetic fields. In addition, our study shows that dominant pinning mechanism changes from point to surface type with increase of magnetic fields. An MgB2 wire heat treated in a high pressure of 1.4 GPa shows a high critical current density of 100 A mm-2 in 13 T at 4.2 K. Scanning electron microscope studies show that high isostatic pressure increases the density of the MgB2 material, eliminates voids, allows for small Si precipitates and homogeneous distribution of Si precipitates. Transport measurements E - B and E - I show that the MgB2 wires manufactured by Hyper Tech Research did not heat up after transition into a normal state. This is important for applications in coils.

  20. The origin of multiple superconducting gaps in MgB2.

    PubMed

    Souma, S; Machida, Y; Sato, T; Takahashi, T; Matsui, H; Wang, S-C; Ding, H; Kaminski, A; Campuzano, J C; Sasaki, S; Kadowaki, K

    2003-05-01

    Magnesium diboride, MgB2, has the highest transition temperature (T(c) = 39 K) of the known metallic superconductors. Whether the anomalously high T(c) can be described within the conventional BCS (Bardeen-Cooper-Schrieffer) framework has been debated. The key to understanding superconductivity lies with the 'superconducting energy gap' associated with the formation of the superconducting pairs. Recently, the existence of two kinds of superconducting gaps in MgB2 has been suggested by several experiments; this is in contrast to both conventional and high-T(c) superconductors. A clear demonstration of two gaps has not yet been made because the previous experiments lacked the ability to resolve the momentum of the superconducting electrons. Here we report direct experimental evidence for the two-band superconductivity in MgB2, by separately observing the superconducting gaps of the sigma and pi bands (as well as a surface band). The gaps have distinctly different sizes, which unambiguously establishes MgB2 as a two-gap superconductor.

  1. Thickness dependence of Jc (0) in MgB2 films

    NASA Astrophysics Data System (ADS)

    Chen, Yiling; Yang, Can; Jia, Chunyan; Feng, Qingrong; Gan, Zizhao

    2016-06-01

    MgB2 superconducting films, whose thicknesses range from 10 nm to 8 μm, have been fabricated on SiC substrates by hybrid physical-chemical vapor deposition (HPCVD) method. It is the first time that the Tc and the Jc of MgB2 films are studied on such a large scale. It is found that with the increasing of thickness, Tc elevates first and then keeps roughly stable except for some slight fluctuations, while Jc (5 K, 0 T) experiences a sharp increase followed by a relatively slow fall. The maximum Jc (5 K, 0 T) = 2.3 × 108 A cm-2 is obtained for 100 nm films, which is the experimental evidence for preparing high-quality MgB2 films by HPCVD method. Thus, this work may provide guidance on choosing the suitable thickness for applications. Meanwhile, the films prepared by us cover ultrathin films, thin films and thick films, so the study on them will bring a comprehensive understanding of MgB2 films.

  2. Enhancement of flux pinning in a MgB2 superconductor doped with tartaric acid

    NASA Astrophysics Data System (ADS)

    Hossain, M. S. A.; Kim, J. H.; Wang, X. L.; Xu, X.; Peleckis, G.; Dou, S. X.

    2007-01-01

    The synthesis and characterization of a carbon (C) doped polycrystalline MgB2 superconductor is reported with tartaric acid (C4H6O6) used as the C source. The amount of C4H6O6 is varied between 5 and 30 wt%. Relationships between microstructures, critical current density (Jc), critical temperature (Tc), upper critical field (Hc2), and irreversibility field (Hirr) for MgB2 doped with 0-30 wt% C4H6O6 are systematically studied. A reduction in Tc from 37.65 to 34.45 K and in lattice parameter a due to the C substitution occurs with C4H6O6 doping. Jc, Hc2, and Hirr are significantly enhanced with an increasing amount of C4H6O6. All the samples exhibit a Jc above 104 A cm-2 at 5 K and 8 T. This value is higher than for un-doped MgB2 by a factor of 6. The significant improvement in the superconducting properties is attributed to the lattice distortion due to the C substitution for boron, with the C coming from the C4H6O6. These findings suggest that C4H6O6 is a promising C source for MgB2 with excellent Jc properties under high field.

  3. Local environments of iron and cobalt in doped MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Kuzmann, E.; Homonnay, Z.; Klencsár, Z.; Kühberger, M.; Vértes, A.; Gritzner, G.

    2002-11-01

    MgB2 has been doped with 57Fe and 57Co in order to probe the electronic structure of the superconductor by Mössbauer spectroscopy. Simultaneous SEM-EDX studies showed that both Fe and Co were incorporated to some extent into the MgB2 host lattice. Mössbauer spectroscopy indicated that Fe2B and FeB were also formed during the preparation. At higher Fe contents Fe2B appeared unambiguously as a secondary phase in the x-ray diffraction. CoB was detected at substitution levels of 10 mol% and greater. Both Fe and Co doping decreased the Tc(0) modestly. Co and Fe were found to substitute at the Mg site in the MgB2 lattice. The Mössbauer parameters for 57Co and 57Fe were consistent with a metallic environment. The similarity of the isomer shifts in MgB2 and in cuprate superconductors is being discussed.

  4. Rational design of MgB2 conductors toward practical applications

    NASA Astrophysics Data System (ADS)

    Patel, Dipak; Hossain, Md Shahriar Al; Motaman, Ashkan; Barua, Shaon; Shahabuddin, Mohammed; Kim, Jung Ho

    2014-09-01

    We report the research progress that has been made on developing rational MgB2 superconducting conductors toward practical applications. Owing to the poor performance of the critical current density (Jc) of bare MgB2, various techniques have been developed to overcome this obstacle. Among these, chemical doping has proved to be the most effective way to enhance the superconducting properties, such as Jc and the irreversibility field (Birr). More than a hundred different forms of dopants have been investigated over the past 13 years. Among these, the most effective dopants have been identified to be silicon carbide, carbon, and malic acid. The best results, Birr of 22 T and Jc of 40,000 A cm-2 at 4.2 K and 10 T, have been reported for malic acid treated MgB2 conductors, which have matched the benchmark performance of commercial low temperature superconductor wire such as Nb-Ti. This work will review and discuss the progress on MgB2 conductor development over the past few years at the University of Wollongong and Hyper Tech Research, Inc.

  5. Solution Fabrication of a Superconducting MgB2 Coated Conductor on Stainless Steel

    NASA Astrophysics Data System (ADS)

    Wang, Yin-Bo; Chen, Li-Ping; Zhang, Chen; Wang, Yue; Guo, Zheng-Shan; Chen, Yi-Ling; Feng, Qing-Rong; Gan, Zi-Zhao

    2012-04-01

    We report the solution fabrication of a MgB2 coated conductor on a stainless steel substrate. The precursor solution of Mg(BH4)2 diethyl ether is initially synthesized by refluxing the milled mixture of NaBH4 and MgCl2 in diethyl ether. Then the Mg(BH4)2 diethyl ether is spin coated on a stainless steel substrate and annealed in Mg vapor, which yields a homogeneous MgB2 coated conductor. X-ray diffraction indicates that the grown MgB2 coated conductor is polycrystalline. It has a superconducting transition temperature of 34-37 K. The slope of the upper critical field HC2 increases with decreasing temperature, and the extrapolated value of HC2(0) reaches ~28 T. The critical current density estimated by the Bean model is JC(25K, 0T)~106 A·cm-2. These parameters indicate that the solution method is potentially able to produce MgB2 coated conductors that can satisfy application purposes.

  6. Influence of magnetic nanoparticles on superconductivity of MgB2

    NASA Astrophysics Data System (ADS)

    Novosel, N.; Babić, E.

    2013-10-01

    Recently we begun systematic study of the influence of magnetic nanoparticles (MNPs) on the superconducting properties (transition temperature Tc, critical fields and critical current density, Jc) of MgB2 wires. We prepared over 60 Fe-sheathed MgB2 wires doped with different types and quantities of MNPs, such as pure metals (Fe, Co, Ni), magnetic borides (Fe2B, Co2B, NiCoB) and ferrites (AFe2O4, A = Mn, Fe, Co, Ni, Cu). Both, uncoated and coated (with silica or dextrin) MNPs were used in order to assess also the effects of co-doping and of interactions between MNPs. All MNPs suppress Tc of MgB2 and higher MNP contents inevitably cause deterioration of superconducting properties of wires. However, light doping (⩽2.5 wt.%) with few species of MNP (Ni, NiCoB and dextrin coated NiFe2O4 and Fe3O4) improved low-temperature, high-field Jc of MgB2 wires. Possible origin of this improvement is briefly discussed.

  7. In-Situ Real Time Monitoring and Control of Mold Making and Filling Processes

    SciTech Connect

    2004-11-01

    This factsheet describes a research effort to develop an innovative approach to introduce technologies for real-time characterization of sand molds, lost foam patterns, and monitoring of the mold filling process. This will reduce scrap, improve product quality, and save energy.

  8. Space Plasma Ion Processing of Ilmenite in the Lunar Soil: Insights from In-Situ TEM Ion Irradiation Experiments

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Keller, L. P.

    2007-01-01

    Space weathering on the moon and asteroids results largely from the alteration of the outer surfaces of regolith grains by the combined effects of solar ion irradiation and other processes that include deposition of impact or sputter-derived vapors. Although no longer considered the sole driver of space weathering, solar ion irradiation remains a key part of the space weathering puzzle, and quantitative data on its effects on regolith minerals are still in short supply. For the lunar regolith, previous transmission electron microscope (TEM) studies performed by ourselves and others have uncovered altered rims on ilmenite (FeTiO3) grains that point to this phase as a unique "witness plate" for unraveling nanoscale space weathering processes. Most notably, the radiation processed portions of these ilmenite rims consistently have a crystalline structure, in contrast to radiation damaged rims on regolith silicates that are characteristically amorphous. While this has tended to support informal designation of ilmenite as a "radiation resistant" regolith mineral, there are to date no experimental data that directly and quantitatively compare ilmenite s response to ion radiation relative to lunar silicates. Such data are needed because the radiation processed rims on ilmenite grains, although crystalline, are microstructurally and chemically complex, and exhibit changes linked to the formation of nanophase Fe metal, a key space weathering process. We report here the first ion radiation processing study of ilmenite performed by in-situ means using the Intermediate Voltage Electron Microscope- Tandem Irradiation facility (IVEM-Tandem) at Argonne National Laboratory. The capability of this facility for performing real time TEM observations of samples concurrent with ion irradiation makes it uniquely suited for studying the dose-dependence of amorphization and other changes in irradiated samples.

  9. Solidification paths and reinforcement morphologies in melt-processed (TiB + TiC)/Ti In Situ Composites

    NASA Astrophysics Data System (ADS)

    Lu, W. J.; Zhang, D.; Wu, R. J.; Mori, H.

    2002-09-01

    A novel in situ process was developed to produce titanium matrix composites reinforced with TiB and TiC of different mole ratios in which traditional ingot metallurgy plus self-propagation hightemperature synthesis (SHS) reactions between Ti and B4C, graphite powder were used. Microstructures of (TiB+TiC)/Ti in situ composites were comprehensively characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Solidification paths were investigated using a differential scanning calorimeter (DSC). Results show that there is an apparent difference in morphologies of reinforcements. The reinforcements nucleate and grow from the melt in a way of dissolution precipitation. The different morphologies are related to their solidification paths and the particular crystal structure of the reinforcement. TiB grows along the [010] direction and forms short-fiber shape due to its B27 structure, whereas TiC with NaCl type structure grows in a dendritic, equiaxed, or near-equiaxed shape. The DSC results and analysis of the phase diagram yield three stages for the solidification paths of in situ synthesized titanium matrix composites: (1) primary phase, (2) monovariant binary eutectic, and (3) invariant ternary eutectic. The addition of graphite adjusts the solidification paths and forms more dendritic primary TiC. The addition of aluminum does not change the solidification paths. However, the reinforcements grow finer and lead to equiaxed or near-equiaxed TiC morphologies. The following consistent crystallographic relationships between TiB and titanium were observed by HRTEM, i.e., [010]TiB//[01bar 10]Ti, (100)TiB//(bar 2110)Ti, (001)TiB//(0002)Ti, (10bar 1)TiB//(4overline {22} 1)Ti and [001]TiB//[01bar 10]Ti, (0bar 10)TiB//(bar 2110)Ti, (200)TiB//(0002)Ti. The formation of the preceding crystallographic relationships is related to the growth mechanism of TiB. It also helps to minimize

  10. Wet cells and dry cells: In situ transmission electron microscopy of electrically-driven, dynamical processes

    NASA Astrophysics Data System (ADS)

    White, Edward Robert, IV

    Recent developments in nanofabrication techniques allow thin, wet systems to be imaged with high spatial and temporal resolution in the electron microscope. Coupling this ability with simultaneous, measured, electrical control, we cycle processes in liquid systems representing different electrochemical battery components. Dynamic processes imaged with these techniques, which represent a new state-of-the-art, include nanobubble collapse, dendrite growth, ion diffusion, and graphite intercalation. We also develop a sensitive system for measuring electron beam induced currents (EBIC) in the transmission electron microscope and apply it to graphene-MoS2 heterostructures. This new hybrid material has strong light-matter interactions, and the EBIC measurements map the minority carrier diffusion length, which we observe to decrease with increasing radiation damage. These results have direct implications for the function and service lifetime of solar cells based on molybdenum disulfide.

  11. In-situ Monitoring of Dynamic Phenomena during Solidification and Phase Transformation Processing

    SciTech Connect

    Clarke, Amy J.; Cooley, Jason C.; Morris, Christopher; Merrill, Frank E.; Hollander, Brian J.; Mariam, Fesseha G.; Patterson, Brian M.; Imhoff, Seth D.; Lee, Wah Keat; Fezzaa, Kamel; Deriy, Alex; Tucker, Tim J.; Clarke, Kester D.; Field, Robert D.; Thoma, Dan J.; Teter, David F.; Beard, Timothy V.; Hudson, Richard W.; Freibert, Franz J.; Korzekwa, Deniece R.; Farrow, Adam M.; Cross, Carl E.; Mihaila, Bogdan; Lookman, Turab; Hunter, Abigail; Choudhury, Samrat; Karma, Alain; Ott, Thomas J. Jr.; Barker, Martha R.; O'Neill, Finian; Hill, Joshua; Emigh, Megan G.

    2012-07-30

    The purpose of this project is to: (1) Directly observe phase transformations and microstructure evolution using proton (and synchrotron x-ray) radiography and tomography; (2) Constrain phase-field models for microstructure evolution; (3) Experimentally control microstructure evolution during processing to enable co-design; and (4) Advance toward the MaRIE vision. Understand microstructure evolution and chemical segregation during solidification {yields} solid-state transformations in Pu-Ga.

  12. Characterization of boron carbide particulate reinforced in situ copper surface composites synthesized using friction stir processing

    SciTech Connect

    Sathiskumar, R.; Murugan, N.; Dinaharan, I.; Vijay, S.J.

    2013-10-15

    Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B{sub 4}C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6 mm thick copper plates and packed with B{sub 4}C particles. The dimensions of the groove was varied to result in five different volume fractions of B{sub 4}C particles (0, 6, 12, 18 and 24 vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000 rpm, travel speed of 40 mm/min and an axial force of 10 kN. Metallurgical characterization of the Cu/B{sub 4}C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B{sub 4}C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B{sub 4}C surface composites. When the volume fraction of B{sub 4}C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. Highlights: • Fabrication of Cu/B{sub 4}C surface composite by friction stir processing • Analyzing the effect of B{sub 4}C particles on the properties of Cu/B4C surface composite • Increased volume fraction of B{sub 4}C particles reduced the area of surface composite. • Increased volume fraction of B{sub 4}C particles enhanced the microhardness and wear rate. • B{sub 4}C particles altered the wear mode from microcutting to abrasive.

  13. ECR plasma cleaning: an in-situ processing technique for RF cavities

    SciTech Connect

    Wu, G.; Moeller, W-D.; Antoine, C.; Jiang, H.; Pechenezhskiy, I.; Cooley, L.; Khabiboulline, T.; Terechkine, Y.; Edwards, H.; Koeth, T.; Romanenko, A.; /Cornell U., Phys. Dept. /Jefferson Lab

    2008-01-01

    A condition for Electron Cyclotron Resonance (ECR) can be established inside a fully assembled RF cavity without the need for removing high-power couplers. As such, plasma generated by this process can be used as a final cleaning step, or as an alternative cleaning step in place of other techniques. Tests showed filtered dry air plasma can successfully remove sulfur particles on niobium surface while the surface oxygen content remains intact.

  14. Analysis of In-Situ Vibration Monitoring for End-Point Detection of CMP Planarization Processes

    SciTech Connect

    Hetherington, Dale L.; Lauffer, James P.; Shingledecker, David M.; Stein, David J.; Wyckoff, Edward E.

    1999-05-14

    This paper details the analysis of vibration monitoring for end-point control in oxide CMP processes. Two piezoelectric accelerometers were integrated onto the backside of a stainless steel polishing head of an IPEC 472 polisher. One sensor was placed perpendicular to the carrier plate (vertical) and the other parallel to the plate (horizontal). Wafers patterned with metal and coated with oxide material were polished at different speeds and pressures. Our results show that it is possible to sense a change in the vibration signal over time during planarization of oxide material on patterned wafers. The horizontal accelerometer showed more sensitivity to change in vibration amplitude compared to the vertical accelerometer for a given polish condition. At low carrier and platen rotation rates, the change in vibration signal over time at fixed frequencies decreased approximately ½ - 1 order of magnitude (over the 2 to 10 psi polish pressure ranges). At high rotation speeds, the vibration signal remained essentially constant indicating that other factors dominated the vibration signaL These results show that while it is possible to sense changes in acceleration during polishing, more robust hardware and signal processing algorithms are required to ensure its use over a wide range of process conditions.

  15. Giant Anharmonicity and Theory of Surprising BCS Superconductivity in MgB2 at 40 K

    NASA Astrophysics Data System (ADS)

    Yildirim, Taner

    2002-03-01

    The recent surprise discovery of superconductivity in MgB2 at 40 K has stimulated a great deal of research on this intercalated grahite-like system. Sparked by this discovery, we set out to unlock the structural secrets and, in particular, to reveal the origin of the high Tc in MgB_2; an electron-phonon or other exotic mechanism? To answer this fundamental question, we calculated T_c, its pressure dependence for uni- and biaxial compressions, and the isotope effect from the electronic band structure and lattice dynamics of MgB2 using density functional theory[1-2]. The calculated phonon density of states (DOS) are in excellent agreement with the inelastic neutron scattering measurements. We find that the in-plane boron phonons near the zone-center are very anharmonic and strongly coupled to the planar B sigma bands near the Fermi level. The boron mass and pressure dependence of this mode is found to be the key to quantitatively explaining the observed high T_c, the total isotope effect, and the pressure dependence of T_c. We propose that a stringent test on the hole and phonon based theories of the superconductivity in MgB2 would be a measurement of the biaxial ab-compression dependence of T_c. In collobration with Oguz Gulseren, NIST and UPENN [1] T. Yildirim et. al., Phys. Rev. Lett. 87, 037001 (2001). [2] For details, see http://www.ncnr.nist.gov/staff/taner/mgb2

  16. In-situ Spectroscopic Ellipsometry of the Cu Deposition Process from Supercritical Fluids: Evidence of an Abnormal Surface Layer Formation

    NASA Astrophysics Data System (ADS)

    Sasaki, Takuya; Tamegai, Yukihiro; Ueno, Takahiro; Watanabe, Mitsuhiro; Jin, Lianhua; Kondoh, Eiichi

    2012-05-01

    In this paper, we report in-situ spectroscopic ellipsometry of Cu deposition from supercritical carbon dioxide fluids. The motivations of this work were 1) to perform a detailed observation of Cu growth with precision optical metrology, 2) to study substrate dependence on Cu growth, particularly for Ru and TiN substrates in the present case, and 3) to demonstrate the possibility and usefulness of ellipsometry for diagnosing supercritical fluid processing. The Cu deposition was carried out through hydrogen reduction of a Cu β-diketonate precursor at 160-180 °C. During growth, a very large deviation of ellipsometric parameters (Ψ and Δ) from a single-layer model prediction was observed; this deviation was much larger than that expected from island formation which has been frequently reported in in-situ ellipsometric observation of the vapor growth of thin films. From model analyses, it was found that an abnormal dielectric layer having a high refractive index and a thickness of 10-50 nm is present on the growing Cu surface. The refractive index of this layer was (1.5-2) + (0.2-0.3)i and from this, we concluded that this layer is the condensed precursor. The condensed layer develops prior to Cu nucleation. As for the substrate dependence on Cu growth, both layers develop faster on Ru than on TiN. This corresponds to the fact that chemisorption occurs more easily on Ru. The deposition kinetics under the presence of the condensed layer are also discussed.

  17. In Situ Detection of Strong Langmuir Turbulence Processes in Solar Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Golla, Thejappa; Macdowall, Robert J.; Bergamo, M.

    2012-01-01

    The high time resolution observations obtained by the WAVES experiment of the STEREO spacecraft in solar type III radio bursts show that Langmuir waves often occur as intense localized wave packets. These wave packets are characterized by short durations of only a few ms and peak intensities, which well exceed the supersonic modulational instability (MI) thresholds. These timescales and peak intensities satisfy the criterion of the solitons collapsed to spatial scales of a few hundred Debye lengths. The spectra of these wave packets consist of primary spectral peaks corresponding to beam-resonant Langmuir waves, two or more sidebands corresponding to down-shifted and up-shifted daughter Langmuir waves, and low frequency enhancements below a few hundred Hz corresponding to daughter ion sound waves. The frequencies and wave numbers of these spectral components satisfy the resonance conditions of the modulational instability (MI). Moreover, the tricoherences, computed using trispectral analysis techniques show that these spectral components are coupled to each other with a high degree of coherency as expected of the MI type of four wave interactions. The high intensities, short scale lengths, sideband spectral structures and low frequency spectral enhancements and, high levels of tricoherences amongst the spectral components of these wave packets provide unambiguous evidence for the supersonic MI and related strong turbulence processes in type III radio bursts. The implication of these observations include: (1) the MI and related strong turbulence processes often occur in type III source regions, (2) the strong turbulence processes probably play very important roles in beam stabilization as well as conversion of Langmuir waves into escaping radiation at the fundamental and second harmonic of the electron plasma frequency, fpe, and (3) the Langmuir collapse probably follows the route of MI in type III radio bursts.

  18. In situ transmission electron microscopy of electron-beam induced damage process in nuclear grade graphite

    SciTech Connect

    C. Karthik; J. Kane; D. P. Butt; W. E. Windes; R. Ubic

    2011-05-01

    Atomic level processes involved in the swelling and crack-closing in nuclear grade graphite under electron irradiation have been observed in real-time using transmission electron microscopy. Noise-filtered lattice images show the formation of vacancy loops, interstitial loops and resulting dislocations with unprecedented clarity. The dislocation dipoles formed via vacancy loops were found to undergo climb resulting in extra basal planes. Concurrent EELS studies showed a reduction in the atomic density because of the breakage of hexagonal carbon rings. The formation of new basal planes via dislocation climb in addition to the bending/breaking of basal planes leads to swelling and closing of micro-cracks.

  19. In situ analysis of repair processes for oxidative DNA damage in mammalian cells

    NASA Astrophysics Data System (ADS)

    Lan, Li; Nakajima, Satoshi; Oohata, Yoshitsugu; Takao, Masashi; Okano, Satoshi; Masutani, Mitsuko; Wilson, Samuel H.; Yasui, Akira

    2004-09-01

    Oxidative DNA damage causes blocks and errors in transcription and replication, leading to cell death and genomic instability. Although repair mechanisms of the damage have been extensively analyzed in vitro, the actual in vivo repair processes remain largely unknown. Here, by irradiation with an UVA laser through a microscope lens, we have conditionally produced single-strand breaks and oxidative base damage at restricted nuclear regions of mammalian cells. We showed, in real time after irradiation by using antibodies and GFP-tagged proteins, rapid and ordered DNA repair processes of oxidative DNA damage in human cells. Furthermore, we characterized repair pathways by using repair-defective mammalian cells and found that DNA polymerase accumulated at single-strand breaks and oxidative base damage by means of its 31- and 8-kDa domains, respectively, and that XRCC1 is essential for both polymerase -dependent and proliferating cell nuclear antigen-dependent repair pathways of single-strand breaks. Thus, the repair of oxidative DNA damage is based on temporal and functional interactions among various proteins operating at the site of DNA damage in living cells.

  20. Endoscopic fringe projection for in-situ inspection of a sheet-bulk metal forming process

    NASA Astrophysics Data System (ADS)

    Matthias, Steffen; Kästner, Markus; Reithmeier, Eduard

    2015-05-01

    Sheet-bulk metal forming is a new production process capable of performing deep-drawing and massive forming steps in a single operation. However, due to the high forming forces of the forming process, continuous process control is required in order to detect wear on the forming tool before production quality is impacted. To be able to measure the geometry of the forming tool in the limited space of forming presses, a new inspection system is being developed within the SFB/TR 73 collaborative research center. In addition to the limited space, the process restricts the amount of time available for inspection. Existing areal optical measurement systems suffer from shadowing when measuring the tool's inner elements, as they cannot be placed in the limited space next to the tool, while tactile measurement systems cannot meet the time restrictions for measuring the areal geometries. The new inspection system uses the fringe projection optical measurement principle to capture areal geometry data from relevant parts of the forming tool in short time. Highresolution image fibers are used to connect the system's compact sensor head to a base unit containing both camera and projector of the fringe projection system, which can be positioned outside of the moving parts of the press. To enable short measurement times, a high intensity laser source is used in the projector in combination with a digital micro-mirror device. Gradient index lenses are featured in the sensor head to allow for a very compact design that can be used in the narrow space above the forming tool inside the press. The sensor head is attached to an extended arm, which also guides the image fibers to the base unit. A rotation stage offers the possibility to capture measurements of different functional elements on the circular forming tool by changing the orientation of the sensor head next to the forming tool. During operation of the press, the arm can be travelled out of the moving parts of the forming press

  1. IN-SITU IONIC CHEMICAL ANALYSIS OF FRESH WATER VIA A NOVEL COMBINED MULTI-SENSOR / SIGNAL PROCESSING ARCHITECTURE

    NASA Astrophysics Data System (ADS)

    Mueller, A. V.; Hemond, H.

    2009-12-01

    The capability for comprehensive, real-time, in-situ characterization of the chemical constituents of natural waters is a powerful tool for the advancement of the ecological and geochemical sciences, e.g. by facilitating rapid high-resolution adaptive sampling campaigns and avoiding the potential errors and high costs related to traditional grab sample collection, transportation and analysis. Portable field-ready instrumentation also promotes the goals of large-scale monitoring networks, such as CUASHI and WATERS, without the financial and human resources overhead required for traditional sampling at this scale. Problems of environmental remediation and monitoring of industrial waste waters would additionally benefit from such instrumental capacity. In-situ measurement of all major ions contributing to the charge makeup of natural fresh water is thus pursued via a combined multi-sensor/multivariate signal processing architecture. The instrument is based primarily on commercial electrochemical sensors, e.g. ion selective electrodes (ISEs) and ion selective field-effect transistors (ISFETs), to promote low cost as well as easy maintenance and reproduction,. The system employs a novel architecture of multivariate signal processing to extract accurate information from in-situ data streams via an "unmixing" process that accounts for sensor non-linearities at low concentrations, as well as sensor cross-reactivities. Conductivity, charge neutrality and temperature are applied as additional mathematical constraints on the chemical state of the system. Including such non-ionic information assists in obtaining accurate and useful calibrations even in the non-linear portion of the sensor response curves, and measurements can be made without the traditionally-required standard additions or ionic strength adjustment. Initial work demonstrates the effectiveness of this methodology at predicting inorganic cations (Na+, NH4+, H+, Ca2+, and K+) in a simplified system containing

  2. A trapped field of >3 T in bulk MgB2 fabricated by uniaxial hot pressing

    NASA Astrophysics Data System (ADS)

    Durrell, J. H.; Dancer, C. E. J.; Dennis, A.; Shi, Y.; Xu, Z.; Campbell, A. M.; Babu, N. Hari; Todd, R. I.; Grovenor, C. R. M.; Cardwell, D. A.

    2012-11-01

    A trapped field of over 3 T has been measured at 17.5 K in a magnetized stack of two disc-shaped bulk MgB2 superconductors of diameter 25 mm and thickness 5.4 mm. The bulk MgB2 samples were fabricated by uniaxial hot pressing, which is a readily scalable, industrial technique, to 91% of their maximum theoretical density. The macroscopic critical current density derived from the trapped field data using the Biot-Savart law is consistent with the measured local critical current density. From this we conclude that critical current density, and therefore trapped field performance, is limited by the flux pinning available in MgB2, rather than by lack of connectivity. This suggests strongly that both increasing sample size and enhancing pinning through doping will allow further increases in trapped field performance of bulk MgB2.

  3. The effect of citric and oxalic acid doping on the superconducting properties of MgB2

    NASA Astrophysics Data System (ADS)

    Ojha, N.; Malik, V. K.; Singla, Rashmi; Bernhard, C.; Varma, G. D.

    2009-12-01

    In this paper we report the effect of carbon doping on the structural and superconducting properties of MgB2 using citric and oxalic acids as carbon sources. The bulk polycrystalline samples have been synthesized via a standard solid state reaction route with composition MgB2+x wt% of citric and oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantly MgB2 with only a small amount of impurity phase MgO and substitution of C at the B site of MgB2 for both dopants. Improvements in the upper critical field (HC2), irreversibility field (Hirr) and high field (>2.5 T) critical current density (JC) have been observed on C doping in the samples. The correlations between superconducting properties and structural characteristics of the samples are described and discussed in this paper.

  4. In-situ wastewater treatment and groundwater remediation at a sugar beet processing facility

    SciTech Connect

    Olson, J.L.; Fuller-Pratt, P.R.; Mielke, R.A.

    1996-06-01

    Groundwater monitoring data collected at the Western Sugar Company sugar beet processing plant, in Billings, Montana identified groundwater mounding and groundwater nitrogen concentration increases associated with lime slurry discharge to an on-site storage pile. The nitrogen impacts (primarily ammonia) likely originated through decomposition of organic matter in the slurry. Initially, Western Sugar considered constructing an expensive anaerobic and nitrification-denitrification wastewater treatment system. However, further investigation of the lime pile revealed that it was already serving as an efficient filter and anaerobic reactor. Comparisons of slurry application with other land application systems suggested that groundwater nitrogen impacts could be minimized through groundwater capture, re-application, and improved slurry management. The resultant system required little capitol and maintenance cost. The immediate effect was to substantially decrease the groundwater mound. Subsequent monitoring has demonstrated a gradual decline in nitrogen concentrations under the lime pile and a considerable concentration decrease downgradient of the groundwater recovery system.

  5. Capturing a failure of an ASIC in-situ, using infrared radiometry and image processing software

    NASA Technical Reports Server (NTRS)

    Ruiz, Ronald P.

    2003-01-01

    Failures in electronic devices can sometimes be tricky to locate-especially if they are buried inside radiation-shielded containers designed to work in outer space. Such was the case with a malfunctioning ASIC (Application Specific Integrated Circuit) that was drawing excessive power at a specific temperature during temperature cycle testing. To analyze the failure, infrared radiometry (thermography) was used in combination with image processing software to locate precisely where the power was being dissipated at the moment the failure took place. The IR imaging software was used to make the image of the target and background, appear as unity. As testing proceeded and the failure mode was reached, temperature changes revealed the precise location of the fault. The results gave the design engineers the information they needed to fix the problem. This paper describes the techniques and equipment used to accomplish this failure analysis.

  6. Microbial fuel cell based biosensor for in situ monitoring of anaerobic digestion process.

    PubMed

    Liu, Zhidan; Liu, Jing; Zhang, Songping; Xing, Xin-Hui; Su, Zhiguo

    2011-11-01

    A wall-jet microbial fuel cell (MFC) was developed for the monitoring of anaerobic digestion (AD). This biofilm based MFC biosensor had a character of being portable, short hydraulic retention time (HRT) for sample flow through and convenient for continuous operation. The MFC was installed in the recirculation loop of an upflow anaerobic fixed-bed (UAFB) reactor in bench-scale where pH of the fermentation broth and biogas flow were monitored in real time. External disturbances to the AD were added on purpose by changing feedstock concentration, as well as process configuration. MFC signals had good correlations with online measurements (i.e. pH, gas flow rate) and offline analysis (i.e. COD) over 6-month operation. These results suggest that the MFC signal can reflect the dynamic variation of AD and can potentially be a valuable tool for monitoring and control of bioprocess.

  7. Using helium as background gas to avoid hydrogen brittleness for MgB2 film fabrication on niobium substrate by HPCVD

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Ni, Zhimao; Chen, Lizhi; Hu, Hui; Yang, Can; Feng, Qingrong; Liu, Kexin

    2016-05-01

    Magnesium diboride has shown potential as an alternative material for the application of superconducting RF cavities. However, if MgB2 films are fabricated on niobium substrates with HPCVD method, hydrogen brittleness will cause cracks on MgB2 film when it is bent. In this work, we have investigated the possibility of depositing MgB2 film on niobium in other background gases rather than hydrogen to avoid hydrogen brittleness. Though MgB2 films fabricated in nitrogen and argon have impurities and show poor superconducting properties, the MgB2 film fabricated in helium has similar morphology and superconducting properties of that prepared in hydrogen and no cracks are observed after bending. The problem of hydrogen brittleness can be solved by using helium as the background gas when fabricating MgB2 films on niobium substrates.

  8. A whole biodiesel conversion process combining isolation, cultivation and in situ supercritical methanol transesterification of native microalgae.

    PubMed

    Jazzar, Souhir; Quesada-Medina, Joaquín; Olivares-Carrillo, Pilar; Marzouki, Mohamed Néjib; Acién-Fernández, Francisco Gabriel; Fernández-Sevilla, José María; Molina-Grima, Emilio; Smaali, Issam

    2015-08-01

    A coupled process combining microalgae production with direct supercritical biodiesel conversion using a reduced number of operating steps is proposed in this work. Two newly isolated native microalgae strains, identified as Chlorella sp. and Nannochloris sp., were cultivated in both batch and continuous modes. Maximum productivities were achieved during continuous cultures with 318mg/lday and 256mg/lday for Chlorella sp. and Nannochloris sp., respectively. Microalgae were further characterized by determining their photosynthetic performance and nutrient removal efficiency. Biodiesel was produced by catalyst-free in situ supercritical methanol transesterification of wet unwashed algal biomass (75wt.% of moisture). Maximum biodiesel yields of 45.62wt.% and 21.79wt.% were reached for Chlorella sp. and Nannochloris sp., respectively. The analysis of polyunsaturated fatty acids of Chlorella sp. showed a decrease in their proportion when comparing conventional and supercritical transesterification processes (from 37.4% to 13.9%, respectively), thus improving the quality of the biodiesel. PMID:25965253

  9. Metallurgical phases and their magnetism at the interface of nanoscale MgB2/Fe layered structures

    NASA Astrophysics Data System (ADS)

    Sahoo, B.; Keune, W.; Kuncser, V.; Becker, H.-W.; Röhlsberger, R.

    2011-11-01

    We report on the characterization of metallurgical phases and their magnetism at the interfaces of nanoscale MgB2/Fe layered structures. MgB2/57Fe multilayers with varying layer thicknesses were prepared by vacuum deposition and investigated, before and after annealing by electrical resistance measurements, x-ray diffraction and 57Fe conversion-electron Mössbauer spectroscopy (CEMS) down to 5 K. Interfacial Fe-B phases, such as Fe2B, were identified by CEMS. A superparamagnetic-to-ferromagnetic transition is observed with increasing 57Fe film thickness. Ultrahigh vacuum annealing at 500 °C of the multilayers leads to strong diffusion of Fe atoms into the boundary regions of the MgB2 layers. MgB2 in the as-grown multilayers is non-superconducting. Structural disorder and the effect of Fe interdiffusion contribute to the suppression of superconductivity in the MgB2 films of all the as-grown multilayers and the thinner annealed multilayers. However, an annealed MgB2/57Fe/MgB2 trilayer with thicker (500 Å) MgB2 layers is observed to be superconducting with an onset temperature of 25 K. At 5 K, the annealed trilayer can be conceived as being strongly chemically modulated, consisting of two partially Fe-doped superconducting MgB2 layers separated by an interdiffused weakly magnetic Fe-B interlayer, which is characterized by a low hyperfine magnetic field Bhf of ˜11 T. This chemically modulated layer structure of the trilayer after annealing was verified by Rutherford backscattering.

  10. Metallurgical phases and their magnetism at the interface of nanoscale MgB2/Fe layered structures.

    PubMed

    Sahoo, B; Keune, W; Kuncser, V; Becker, H-W; Röhlsberger, R

    2011-11-30

    We report on the characterization of metallurgical phases and their magnetism at the interfaces of nanoscale MgB(2)/Fe layered structures. MgB(2)/(57)Fe multilayers with varying layer thicknesses were prepared by vacuum deposition and investigated, before and after annealing by electrical resistance measurements, x-ray diffraction and (57)Fe conversion-electron Mössbauer spectroscopy (CEMS) down to 5 K. Interfacial Fe-B phases, such as Fe(2)B, were identified by CEMS. A superparamagnetic-to-ferromagnetic transition is observed with increasing (57)Fe film thickness. Ultrahigh vacuum annealing at 500 °C of the multilayers leads to strong diffusion of Fe atoms into the boundary regions of the MgB(2) layers. MgB(2) in the as-grown multilayers is non-superconducting. Structural disorder and the effect of Fe interdiffusion contribute to the suppression of superconductivity in the MgB(2) films of all the as-grown multilayers and the thinner annealed multilayers. However, an annealed MgB(2)/(57)Fe/MgB(2) trilayer with thicker (500 Å) MgB(2) layers is observed to be superconducting with an onset temperature of 25 K. At 5 K, the annealed trilayer can be conceived as being strongly chemically modulated, consisting of two partially Fe-doped superconducting MgB(2) layers separated by an interdiffused weakly magnetic Fe-B interlayer, which is characterized by a low hyperfine magnetic field B(hf) of ∼11 T. This chemically modulated layer structure of the trilayer after annealing was verified by Rutherford backscattering.

  11. From E2g to other modes: effects of pressure on electron-phonon interaction in MgB2.

    PubMed

    Singh, Prabhakar P

    2006-12-15

    We study the effects of pressure on the electron-phonon interaction in MgB2 using density-functional-based methods. Our results show that the superconductivity in MgB2 vanishes by 100 GPa, and then reappears at higher pressures. In particular, we find a superconducting transition temperature Tc approximately 2 K for mu*=0.1 at a pressure of 137 GPa.

  12. Observation of multiband effects in the microwave complex conductivity of pure and Al-doped MgB 2 samples

    NASA Astrophysics Data System (ADS)

    Di Gennaro, E.; Lamura, G.; Palenzona, A.; Putti, M.; Andreone, A.

    2004-08-01

    There is presently a general agreement that the simple inter-metallic compound MgB 2 is a conventional, phonon mediated, superconductor, and that the anomalies in its behaviour can be consistently explained by the existence of two different gaps. We present a study of the complex conductivity as a function of temperature in pure and Al-doped MgB 2 pellets by using a dielectrically loaded resonant cavity at 19 GHz.

  13. In situ electron spin resonance and Raman spectroscopic studies of the electrochemical process of conducting polypyrrole films

    SciTech Connect

    Zhong, C.J.; Tian, Z.Q.; Tian, Z.W. )

    1990-03-08

    The electrochemical redox properties of conducting polypyrrole (PPy) films coated on electrodes are investigated in aqueous solutions by use of the in situ techniques of electron spin resonance (ESR) and Raman spectroscopy. Comparisons between the experimental in situ ESR data and a theoretical kinetic prediction on the basis of the polaron-bipolaron model are presented.

  14. In–situ Spatiotemporal Chemical Reactions at Water-Solid Interfacial Processes using Microelectrode Techniques: from Biofilm to Metal Corrosion

    EPA Science Inventory

    Recent developments in microscale sensors allows the non-destructive and in–situ measurement of both the absolute and changes in chemical concentrations in engineered and natural aquatic systems. Microelectrodes represent a unique tool for studying in–situ chemical reactions in b...

  15. Visualization of Freezing Process in situ upon Cooling and Warming of Aqueous Solutions

    PubMed Central

    Bogdan, Anatoli; Molina, Mario J.; Tenhu, Heikki; Bertel, Erminald; Bogdan, Natalia; Loerting, Thomas

    2014-01-01

    The freezing of aqueous solutions and reciprocal distribution of ice and a freeze-concentrated solution (FCS) are poorly understood in spite of their importance in fields ranging from biotechnology and life sciences to geophysics and climate change. Using an optical cryo-miscroscope and differential scanning calorimetry, we demonstrate that upon cooling of citric acid and sucrose solutions a fast freezing process results in a continuous ice framework (IF) and two freeze-concentrated solution regions of different concentrations, FCS1 and FCS2. The FCS1 is maximally freeze-concentrated and interweaves with IF. The less concentrated FCS2 envelops the entire IF/FCS1. We find that upon further cooling, the FCS1 transforms to glass, whereas the slow freezing of FCS2 continues until it is terminated by a FCS2-glass transition. We observe the resumed slow freezing of FCS2 upon subsequent warming. The net thermal effect of the resumed freezing and a reverse glass-FCS1 transition produces the Ttr2-transition which before has only been observed upon warming of frozen hydrocarbon solutions and which nature has remained misunderstood for decades. PMID:25491562

  16. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    SciTech Connect

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

    2015-05-11

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

  17. Ultrahigh surface area carbon from carbonated beverages. Combining self-templaing process and in situ activation

    DOE PAGES

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

    2015-05-11

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

  18. Laser processing and in-situ diagnostics for crystallization: from thin films to nanostructures

    NASA Astrophysics Data System (ADS)

    Yoo, Jae-Hyuck; In, Jung Bin; Zheng, Andy Cheng; Ryu, Sang-Gil; Hwang, David J.; Xiang, Bin; Minor, Andrew M.; Grigoropoulos, Costas P.

    2014-10-01

    Recent work on laser-induced crystallization of thin films and nanostructures is presented. Characterization of the morphology of the crystallized area reveals the optimum conditions for sequential lateral growth in a-Si thin films under high-pulsed laser irradiation. Silicon crystal grains of several micrometers in lateral dimensions can be obtained reproducibly. Laser-induced grain morphology change is observed in silicon nanopillars under a transmission electron microscopy (TEM) environment. The TEM is coupled with a near-field scanning optical microscopy (NSOM) pulsed laser processing system. This combination enables immediate scrutiny on the grain morphologies that the pulsed laser irradiation produces. The tip of the amorphous or polycrystalline silicon pillar is transformed into a single crystalline domain via melt-mediated crystallization. The microscopic observation provides a fundamental basis for laser-induced conversion of amorphous nanostructures into coarse-grained crystals. A laser beam shaping strategy is introduced to control the stochastic dewetting of ultrathin silicon film on a foreign substrate under thermal stimulation. Upon a single pulse irradiation of the shaped laser beam, the thermodynamically unstable ultrathin silicon film is dewetted from the glass substrate and transformed to a nanodome. The results suggest that the laser beam shaping strategy for the thermocapillary-induced de-wetting combined with the isotropic etching is a simple alternative for scalable manufacturing of array of nanostructures.

  19. Visualization of freezing process in situ upon cooling and warming of aqueous solutions.

    PubMed

    Bogdan, Anatoli; Molina, Mario J; Tenhu, Heikki; Bertel, Erminald; Bogdan, Natalia; Loerting, Thomas

    2014-12-10

    The freezing of aqueous solutions and reciprocal distribution of ice and a freeze-concentrated solution (FCS) are poorly understood in spite of their importance in fields ranging from biotechnology and life sciences to geophysics and climate change. Using an optical cryo-microscope and differential scanning calorimetry, we demonstrate that upon cooling of citric acid and sucrose solutions a fast freezing process results in a continuous ice framework (IF) and two freeze-concentrated solution regions of different concentrations, FCS1 and FCS2. The FCS1 is maximally freeze-concentrated and interweaves with IF. The less concentrated FCS2 envelops the entire IF/FCS1. We find that upon further cooling, the FCS1 transforms to glass, whereas the slow freezing of FCS2 continues until it is terminated by a FCS2-glass transition. We observe the resumed slow freezing of FCS2 upon subsequent warming. The net thermal effect of the resumed freezing and a reverse glass-FCS1 transition produces the Ttr2-transition which before has only been observed upon warming of frozen hydrocarbon solutions and which nature has remained misunderstood for decades.

  20. A new highly automated sputter equipment for in situ investigation of deposition processes with synchrotron radiation

    SciTech Connect

    Doehrmann, Ralph; Botta, Stephan; Buffet, Adeline; Santoro, Gonzalo; Schlage, Kai; Schwartzkopf, Matthias; Risch, Johannes F. H.; Mannweiler, Roman; Roth, Stephan V.; Bommel, Sebastian; Brunner, Simon; Metwalli, Ezzeldin; Mueller-Buschbaum, Peter

    2013-04-15

    HASE (Highly Automated Sputter Equipment) is a new mobile setup developed to investigate deposition processes with synchrotron radiation. HASE is based on an ultra-high vacuum sputter deposition chamber equipped with an in-vacuum sample pick-and-place robot. This enables a fast and reliable sample change without breaking the vacuum conditions and helps to save valuable measurement time, which is required for experiments at synchrotron sources like PETRA III at DESY. An advantageous arrangement of several sputter guns, mounted on a rotative flange, gives the possibility to sputter under different deposition angles or to sputter different materials on the same substrate. The chamber is also equipped with a modular sample stage, which allows for the integration of different sample environments, such as a sample heating and cooling device. The design of HASE is unique in the flexibility. The combination of several different sputtering methods like standard deposition, glancing angle deposition, and high pressure sputter deposition combined with heating and cooling possibil-ities of the sample, the large exit windows, and the degree of automation facilitate many different grazing incidence X-ray scattering experiments, such as grazing incidence small and wide angle X-ray scattering, in one setup. In this paper we describe in detail the design and the performance of the new equipment and present the installation of the HASE apparatus at the Micro and Nano focus X-ray Scattering beamline (MiNaXS) at PETRA III. Furthermore, we describe the measurement options and present some selected results. The HASE setup has been successfully commissioned and is now available for users.

  1. A new highly automated sputter equipment for in situ investigation of deposition processes with synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Döhrmann, Ralph; Botta, Stephan; Buffet, Adeline; Santoro, Gonzalo; Schlage, Kai; Schwartzkopf, Matthias; Bommel, Sebastian; Risch, Johannes F. H.; Mannweiler, Roman; Brunner, Simon; Metwalli, Ezzeldin; Müller-Buschbaum, Peter; Roth, Stephan V.

    2013-04-01

    HASE (Highly Automated Sputter Equipment) is a new mobile setup developed to investigate deposition processes with synchrotron radiation. HASE is based on an ultra-high vacuum sputter deposition chamber equipped with an in-vacuum sample pick-and-place robot. This enables a fast and reliable sample change without breaking the vacuum conditions and helps to save valuable measurement time, which is required for experiments at synchrotron sources like PETRA III at DESY. An advantageous arrangement of several sputter guns, mounted on a rotative flange, gives the possibility to sputter under different deposition angles or to sputter different materials on the same substrate. The chamber is also equipped with a modular sample stage, which allows for the integration of different sample environments, such as a sample heating and cooling device. The design of HASE is unique in the flexibility. The combination of several different sputtering methods like standard deposition, glancing angle deposition, and high pressure sputter deposition combined with heating and cooling possibil-ities of the sample, the large exit windows, and the degree of automation facilitate many different grazing incidence X-ray scattering experiments, such as grazing incidence small and wide angle X-ray scattering, in one setup. In this paper we describe in detail the design and the performance of the new equipment and present the installation of the HASE apparatus at the Micro and Nano focus X-ray Scattering beamline (MiNaXS) at PETRA III. Furthermore, we describe the measurement options and present some selected results. The HASE setup has been successfully commissioned and is now available for users.

  2. A new highly automated sputter equipment for in situ investigation of deposition processes with synchrotron radiation.

    PubMed

    Döhrmann, Ralph; Botta, Stephan; Buffet, Adeline; Santoro, Gonzalo; Schlage, Kai; Schwartzkopf, Matthias; Bommel, Sebastian; Risch, Johannes F H; Mannweiler, Roman; Brunner, Simon; Metwalli, Ezzeldin; Müller-Buschbaum, Peter; Roth, Stephan V

    2013-04-01

    HASE (Highly Automated Sputter Equipment) is a new mobile setup developed to investigate deposition processes with synchrotron radiation. HASE is based on an ultra-high vacuum sputter deposition chamber equipped with an in-vacuum sample pick-and-place robot. This enables a fast and reliable sample change without breaking the vacuum conditions and helps to save valuable measurement time, which is required for experiments at synchrotron sources like PETRA III at DESY. An advantageous arrangement of several sputter guns, mounted on a rotative flange, gives the possibility to sputter under different deposition angles or to sputter different materials on the same substrate. The chamber is also equipped with a modular sample stage, which allows for the integration of different sample environments, such as a sample heating and cooling device. The design of HASE is unique in the flexibility. The combination of several different sputtering methods like standard deposition, glancing angle deposition, and high pressure sputter deposition combined with heating and cooling possibilities of the sample, the large exit windows, and the degree of automation facilitate many different grazing incidence X-ray scattering experiments, such as grazing incidence small and wide angle X-ray scattering, in one setup. In this paper we describe in detail the design and the performance of the new equipment and present the installation of the HASE apparatus at the Micro and Nano focus X-ray Scattering beamline (MiNaXS) at PETRA III. Furthermore, we describe the measurement options and present some selected results. The HASE setup has been successfully commissioned and is now available for users. PMID:23635203

  3. New in situ solid-state NMR techniques for probing the evolution of crystallization processes: pre-nucleation, nucleation and growth.

    PubMed

    Hughes, Colan E; Williams, P Andrew; Keast, Victoria L; Charalampopoulos, Vasileios G; Edwards-Gau, Gregory R; Harris, Kenneth D M

    2015-01-01

    The application of in situ techniques for investigating crystallization processes promises to yield significant new insights into fundamental aspects of crystallization science. With this motivation, we recently developed a new in situ solid-state NMR technique that exploits the ability of NMR to selectively detect the solid phase in heterogeneous solid-liquid systems (of the type that exist during crystallization from solution), with the liquid phase "invisible" to the measurement. As a consequence, the technique allows the first solid particles produced during crystallization to be observed and identified, and allows the evolution of different solid phases (e.g., polymorphs) present during the crystallization process to be monitored as a function of time. This in situ solid-state NMR strategy has been demonstrated to be a powerful approach for establishing the sequence of solid phases produced during crystallization and for the discovery of new polymorphs. The most recent advance of the in situ NMR methodology has been the development of a strategy (named "CLASSIC NMR") that allows both solid-state NMR and liquid-state NMR spectra to be measured (essentially simultaneously) during the crystallization process, yielding information on the complementary changes that occur in both the solid and liquid phases as a function of time. In this article, we present new results that highlight the application of our in situ NMR techniques to successfully unravel different aspects of crystallization processes, focusing on: (i) the application of a CLASSIC NMR approach to monitor competitive inclusion processes in solid urea inclusion compounds, (ii) exploiting liquid-state NMR to gain insights into co-crystal formation between benzoic acid and pentafluorobenzoic acid, and (iii) applications of in situ solid-state NMR for the discovery of new solid forms of trimethylphosphine oxide and L-phenylalanine. Finally, the article discusses a number of important fundamental issues

  4. Effect of combined addition of nano-SiC and nano-Ho2O3 on the in-field critical current density of MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Varghese, Neson; Vinod, K.; Chattopadhyay, M. K.; Roy, S. B.; Syamaprasad, U.

    2010-01-01

    MgB2 superconducting samples added with nano-Ho2O3 (n-Ho2O3) and/or nano-SiC (n-SiC) have been prepared by an in situ solid state reaction method to investigate and compare the combined and individual effects of n-SiC and n-Ho2O3 on a crystal structure, critical temperature (TC), and critical current density (JC) of MgB2. All the doped samples exhibit significantly enhanced in-field JC and the codoped sample with 2.5 wt % n-Ho2O3 and 5 wt % n-SiC gives the best performance in in-field JC, and the enhancement is around 100 times and 2 times greater than the undoped and monodoped n-SiC samples, respectively, at 5 K and 8 T. For the n-SiC added sample, lattice distortions due to C substitution on the B site and the formation of reacted phase Mg2Si as flux pinners cause enhanced JC up to the maximum field studied (8 T). While in the n-Ho2O3 added sample, a reacted phase HoB4 having a strong magnetic moment forms, without any substitution at the Mg or B site, which acts as a flux pinner in order to enhance the in-field JC. Accordingly the best codoped sample exhibits these combined benefits of n-SiC and n-Ho2O3 in MgB2 superconductor.

  5. Polyaniline-Coated Carbon Nanotube Ultrafiltration Membranes: Enhanced Anodic Stability for In Situ Cleaning and Electro-Oxidation Processes.

    PubMed

    Duan, Wenyan; Ronen, Avner; Walker, Sharon; Jassby, David

    2016-08-31

    Electrically conducting membranes (ECMs) have been reported to be efficient in fouling prevention and destruction of aqueous chemical compounds. In the current study, highly conductive and anodically stable composite polyaniline-carbon nanotube (PANI-CNT) ultrafiltration (UF) ECMs were fabricated through a process of electropolymerization of aniline on a CNT substrate under acidic conditions. The resulting PANI-CNT UF ECMs were characterized by scanning electron microscopy, atomic force microscopy, a four-point conductivity probe, cyclic voltammetry, and contact angle goniometry. The utilization of the PANI-CNT material led to significant advantages, including: (1) increased electrical conductivity by nearly an order of magnitude; (2) increased surface hydrophilicity while not impacting membrane selectivity or permeability; and (3) greatly improved stability under anodic conditions. The membrane's anodic stability was evaluated in a pH-controlled aqueous environment under a wide range of anodic potentials using a three-electrode cell. Results indicate a significantly reduced degradation rate in comparison to a CNT-poly(vinyl alcohol) ECM under high anodic potentials. Fouling experiments conducted with bovine serum albumin demonstrated the capacity of the PANI-CNT ECMs for in situ oxidative cleaning, with membrane flux restored to its initial value under an applied potential of 3 V. Additionally, a model organic compound (methylene blue) was electrochemically transformed at high efficiency (90%) in a single pass through the anodically charged ECM. PMID:27525344

  6. In-situ deposition and processing of YBa2Cu3O(7-x) films and multilayers for optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Villegier, J. C.; Moriceau, H.; Boucher, H.; di Cioccio, L.; Chicault, R.

    1991-03-01

    In situ direct deposition at about 700 C of thin YBa2Cu3O(7-x) superconductive films and multilayers has been done by three techniques using stoichiometric YBa2Cu3O(7-x) sintered targets. Excimer laser ablation in a dc magnetron system with hollow and planar targets leads to 0.5-, 1.2-, and 2.5-in diameter uniformly superconductive layers under static conditions. High critical current densities associated with low resistivity and good epitaxial behavior are achieved on top of MgO, SrTiO3, LaAlO3, and YSZ single-crystal wafers. High-quality c-oriented films are routinely obtained by means of a dc magnetron on large sapphire substrates covered by a YSZ RF sputtered buffer layer. The infrared properties of such films have been checked at 1.15-micron wavelength. In order to achieve active devices, small YBa2Cu3O7-YSZ-Ag tunnel junctions and arrays have been successfully patterned in the superconductor/insulator/normal-metal trilayers using SNOP (selective niobium overlap process).

  7. Polyaniline-Coated Carbon Nanotube Ultrafiltration Membranes: Enhanced Anodic Stability for In Situ Cleaning and Electro-Oxidation Processes.

    PubMed

    Duan, Wenyan; Ronen, Avner; Walker, Sharon; Jassby, David

    2016-08-31

    Electrically conducting membranes (ECMs) have been reported to be efficient in fouling prevention and destruction of aqueous chemical compounds. In the current study, highly conductive and anodically stable composite polyaniline-carbon nanotube (PANI-CNT) ultrafiltration (UF) ECMs were fabricated through a process of electropolymerization of aniline on a CNT substrate under acidic conditions. The resulting PANI-CNT UF ECMs were characterized by scanning electron microscopy, atomic force microscopy, a four-point conductivity probe, cyclic voltammetry, and contact angle goniometry. The utilization of the PANI-CNT material led to significant advantages, including: (1) increased electrical conductivity by nearly an order of magnitude; (2) increased surface hydrophilicity while not impacting membrane selectivity or permeability; and (3) greatly improved stability under anodic conditions. The membrane's anodic stability was evaluated in a pH-controlled aqueous environment under a wide range of anodic potentials using a three-electrode cell. Results indicate a significantly reduced degradation rate in comparison to a CNT-poly(vinyl alcohol) ECM under high anodic potentials. Fouling experiments conducted with bovine serum albumin demonstrated the capacity of the PANI-CNT ECMs for in situ oxidative cleaning, with membrane flux restored to its initial value under an applied potential of 3 V. Additionally, a model organic compound (methylene blue) was electrochemically transformed at high efficiency (90%) in a single pass through the anodically charged ECM.

  8. Calcium phosphate thin film processing by pulsed laser deposition and in situ assisted ultraviolet pulsed laser deposition.

    PubMed

    Nelea, V; Pelletier, H; Iliescu, M; Werckmann, J; Craciun, V; Mihailescu, I N; Ristoscu, C; Ghica, C

    2002-12-01

    Calcium orthophosphates (CaP) and hydroxyapatite (HA) were intensively studied in order to design and develop a new generation of bioactive and osteoconductive bone prostheses. The main drawback now in the CaP and HA thin films processing persists in their poor mechanical characteristics, namely hardness, tensile and cohesive strength, and adherence to the metallic substrate. We report here a critical comparison between the microstructure and mechanical properties of HA and CaP thin films grown by two methods. The films were grown by KrF* pulsed laser deposition (PLD) or KrF* pulsed laser deposition assisted by in situ ultraviolet radiation emitted by a low pressure Hg lamp (UV-assisted PLD). The PLD films were deposited at room temperature, in vacuum on Ti-5Al-2.5Fe alloy substrate previously coated with a TiN buffer layer. After deposition the films were annealed in ambient air at 500-600 degrees C. The UV-assisted PLD films were grown in (10(-2)-10(-1) Pa) oxygen directly on Ti-5Al-2.5Fe substrates heated at 500-600 degrees C. The films grown by classical PLD are crystalline and stoichiometric. The films grown by UV-assisted PLD were crystalline and exhibit the best mechanical characteristics with values of hardness and Young modulus of 6-7 and 150-170 GPa, respectively, which are unusually high for the calcium phosphate ceramics. To the difference of PLD films, in the case of UV-assisted PLD, the GIXRD spectra show the decomposition of HA in Ca(2)P(2)O(7), Ca(2)P(2)O(9) and CaO. The UV lamp radiation enhanced the gas reactivity and atoms mobility during processing, increasing the tensile strength of the film, while the HA structure was destroyed.

  9. Strong interaction between electrons and collective excitations in the multiband superconductor MgB2

    DOE PAGES

    Mou, Daixiang; Jiang, Rui; Taufour, Valentin; Flint, Rebecca; Bud'ko, S. L.; Canfield, P. C.; Wen, J. S.; Xu, Z. J.; Gu, Genda; Kaminski, Adam

    2015-04-08

    We use a tunable laser angle-resolved photoemission spectroscopy to study the electronic properties of the prototypical multiband BCS superconductor MgB2. Our data reveal a strong renormalization of the dispersion (kink) at ~65meV, which is caused by the coupling of electrons to the E2g phonon mode. In contrast to cuprates, the 65 meV kink in MgB2 does not change significantly across Tc. More interestingly, we observe strong coupling to a second, lower energy collective mode at a binding energy of 10 meV. As a result, this excitation vanishes above Tc and is likely a signature of the elusive Leggett mode.

  10. Hydrogen cooling options for MgB2-based superconducting systems

    NASA Astrophysics Data System (ADS)

    Stautner, W.; Xu, M.; Mine, S.; Amm, K.

    2014-01-01

    With the arrival of MgB2 for low-cost superconducting magnets, hydrogen cooling has become an interesting alternative to costly liquid helium. Hydrogen is generally regarded as the most efficient coolant in cryogenics and, in particular, is well suited for cooling superconducting magnets. Cooling methods need to take into account the specific quench propagation in the MgB2 magnet winding and facilitate a cryogenically reliable and safe cooling environment. The authors propose three different multi-coolant options for MRI scanners using helium or hydrogen within the same design framework. Furthermore, a design option for whole-body scanners which employs technology, components, fueling techniques and safety devices from the hydrogen automotive industry is presented, continuing the trend towards replacing helium with hydrogen as a safe and cost efficient coolant.

  11. Magnetic nanoparticles in MgB2: Vortex pinning, pair breaking and connectivity

    NASA Astrophysics Data System (ADS)

    Babić, Emil; Novosel, Nikolina; Pajić, Damir; Galić, Stipe; Zadro, Krešo; Drobac, Đuro

    2016-02-01

    The results indicating magnetic flux pinning in MgB2 wires doped with three types of magnetic nanoparticles (MNP) are reported. The magnetic state of MNPs, both as-prepared and inside the MgB2 core, was determined with magnetization and ac susceptibility measurements. The competition between detrimental influence of doping (reduced connectivity, pair breaking) and enhanced flux pinning leads to deterioration of electromagnetic properties of doped wires at high MNP content, whereas light doping causes an enhancement of critical current density, Jc, and/or irreversibility field, Birr, for all our MNPs. For Ni and dextrin coated NiFe2O4 MNPs the enhancement of Jc was comparable to that achieved with the best nonmagnetic dopands. Detailed analysis indicates the contribution of magnetic flux pinning including the matching effects in flux pinning on MNPs.

  12. Large anisotropic normal-state magnetoresistance in clean MgB2 thin films.

    PubMed

    Li, Qi; Liu, B T; Hu, Y F; Chen, J; Gao, H; Shan, L; Wen, H H; Pogrebnyakov, A V; Redwing, J M; Xi, X X

    2006-04-28

    We report a large normal-state magnetoresistance with temperature-dependent anisotropy in very clean epitaxial MgB2 thin films (residual resistivity much smaller than 1 microOmega cm) grown by hybrid physical-chemical vapor deposition. The magnetoresistance shows a complex dependence on the orientation of the applied magnetic field, with a large magnetoresistance (Delta(rho)/(rho)0=136%) observed for the field H perpendicular ab plane. The angular dependence changes dramatically as the temperature is increased, and at high temperatures the magnetoresistance maximum changes to H||ab. We attribute the large magnetoresistance and the evolution of its angular dependence with temperature to the multiple bands with different Fermi surface topology in MgB2 and the relative scattering rates of the sigma and pi bands, which vary with temperature due to stronger electron-phonon coupling for the sigma bands.

  13. Electronic structure of MgB2 from angle-resolved photoemission spectroscopy.

    PubMed

    Uchiyama, H; Shen, K M; Lee, S; Damascelli, A; Lu, D H; Feng, D L; Shen, Z-X; Tajima, S

    2002-04-15

    The first angle-resolved photoemission spectroscopy results from MgB2 single crystals are reported. Along the GammaK and GammaM directions, we observed three distinct dispersive features approaching the Fermi energy. These can be assigned to the theoretically predicted sigma (B 2p(x,y)) and pi (B 2p(z)) bands. In addition, a small parabolic-like band is detected around the Gamma point, which can be attributed to a surface-derived state. The overall agreement between our results and the band calculations suggests that the electronic structure of MgB2 is of a conventional nature, thus implying that electron correlations are weak and may be of little importance to superconductivity in this system.

  14. Optical properties of c-axis oriented superconducting MgB2 films.

    PubMed

    Tu, J J; Carr, G L; Perebeinos, V; Homes, C C; Strongin, M; Allen, P B; Kang, W N; Choi, E M; Kim, H J; Lee, S I

    2001-12-31

    Temperature dependent optical conductivities and dc resistivity of c-axis oriented superconducting (T(c) = 39.6 K) MgB2 films (approximately 450 nm) have been measured. The normal state ab-plane optical conductivities can be described by the Drude model with a temperature independent Drude plasma frequency of omega(p,D) = 13 600+/-100 cm(-1) or 1.68+/-0.01 eV. The normal state resistivity is fitted by the Bloch-Grüneisen formula with an electron-phonon coupling constant lambda(tr) = 0.13+/-0.02. The optical conductivity spectra below T(c) of these films suggest that MgB2 is a multigap superconductor.

  15. Direct observation of charge re-distribution in a MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Wu, Sheng Yun; Shih, Po-Hsun; Ji, Jhong-Yi; Chan, Ting-Shan; Yang, Chun Chuen

    2016-04-01

    To study the origin of negative thermal expansion effects near the superconducting transition temperature TC in MgB2, low-temperature high-energy synchrotron radiation x-ray diffraction was used to probe the charge redistribution near the boron atoms. Our results reveal that the in-plane hole-distribution of B- hops through the direct orbital overlap of Mg2+ along the c-axis at 50 K and is re-distributed out-of-plane. This study shows that the out-of-plane π-hole distribution plays a dominant role in the possible origin of superconductivity and negative thermal effects in MgB2.

  16. Anisotropies of the lower and upper critical fields in MgB2 single crystals.

    PubMed

    Lyard, L; Szabó, P; Klein, T; Marcus, J; Marcenat, C; Kim, K H; Kang, B W; Lee, H S; Lee, S I

    2004-02-01

    The temperature dependence of the upper (H(c2)) and lower (H(c1)) critical fields has been deduced from Hall probe magnetization measurements of high quality MgB2 single crystals along the two main crystallographic directions. We show that Gamma(H(c2))=H(c2 axially ab)/H(c2 axially c) and Gamma(H(c1))=H(c1 axially c)/H(c1 axially ab) differ significantly at low temperature (being approximately 5 and approximately 1, respectively) and have opposite temperature dependencies. We suggest that MgB2 can be described by a single field dependent anisotropy parameter gamma(H) (=lambda(c)/lambda(ab)=xi(ab)/xi(c)) that increases from Gamma(H(c1)) at low field to Gamma(H(c2)) at high field.

  17. Effects of glucose doping on the MgB2 superconductors using cheap crystalline boron

    NASA Astrophysics Data System (ADS)

    Parakkandy, Jafar Meethale; Shahabuddin, Mohammed; Shah, M. Shahabuddin; Alzayed, Nasser S.; Qaid, Salem A. S.; Madhar, Niyaz Ahmad; Ramay, Shahid M.; Shar, Muhammad Ali

    2015-12-01

    We report the effect of glucose (C6H12O6) doping on the structural and electromagnetic properties of MgB2 superconductor fabricated by dry mixing using planetary ball milling. Herein, as-prepared bulk polycrystalline Mg (B1-xCx) 2 samples with different doping levels (x = 0, 2, 4, and 6 at. %) were systematically studied by X-ray diffraction, magnetic and resistivity measurements, and microstructure analysis. When carbon doped, the reduction in critical transition temperature and shrinkage in a-lattice were obviously observed. This resulted in structural distortion of the MgB2 lattice, and thereby, enhanced an impurity scattering. In addition to these, upper critical field and high-field critical current densities were also enhanced. On the other hand, both pinning force and low-field critical current density are decreased. The high field enhancement and low field degradation are due to increase in impurity scattering and decrease in pinning force respectively.

  18. Ab initio investigation of collective charge excitations in MgB2.

    PubMed

    Ku, Wei; Pickett, W E; Scalettar, R T; Eguiluz, A G

    2002-02-01

    A sharp collective charge excitation is predicted in MgB2 at approximately 2.5 eV for q perpendicular to the boron layers, based on an all-electron analysis of the dynamical density response within time-dependent density functional theory. This novel excitation, consisting of coherent charge fluctuation between Mg and B sheets, induces an abrupt plasma edge in the experimentally observable reflectivity. The existence of this mode reflects the unique electronic structure of MgB2 that is also responsible for strong electron-phonon coupling. By contrast, the acoustic plasmon, recently suggested to explain the high T(c), is not realized when realistic transition strengths are incorporated.

  19. Specific heat and thermal conductivity in the mixed state of MgB2.

    PubMed

    Tewordt, L; Fay, D

    2002-09-23

    The specific heat C and the electronic and phononic thermal conductivities kappa(e) and kappa(ph) are calculated in the mixed state for magnetic fields H near H(c2), including the effects of supercurrent flow and Andreev scattering. The resulting function C(H) is nearly linear while kappa(e)(H) exhibits an upward curvature near H(c2). The slopes decrease with impurity scattering which improves the agreement with the data on MgB2. The ratio of phonon relaxation times tau(n)/tau(s)=g(omega(0),H) for phonon energy omega(0) is smeared out around omega(0)=2Delta and tends to one for increasing H. This leads to a rapid reduction of kappa(ph)(H) in MgB2 for relatively small fields due to the rapid suppression of the smaller energy gap.

  20. Temperature-dependent anisotropy of the penetration depth and coherence length of MgB2.

    PubMed

    Fletcher, J D; Carrington, A; Taylor, O J; Kazakov, S M; Karpinski, J

    2005-08-26

    We report measurements of the temperature-dependent anisotropies (gamma(lambda) and gamma(xi)) of both the London penetration depth lambda and the upper critical field of MgB2. Data for gamma(lambda)=lambda(c)/lambda(a) was obtained from measurements of lambda(a) and lambda(c) on a single crystal sample using a tunnel diode oscillator technique. gamma(xi)=H(perp)c(c2)/H(||c)(c2) was deduced from field-dependent specific heat measurements on the same sample. Gamma(lambda) and gamma(xi) have opposite temperature dependencies, but close to T(c) tend to a common value (gamma(lambda) similar or equal to gamma(xi)=1.75 +/- 0.05). These results are in good agreement with theories accounting for the two-gap nature of MgB2.

  1. High T(c) superconductivity in MgB2 by nonadiabatic pairing.

    PubMed

    Cappelluti, E; Ciuchi, S; Grimaldi, C; Pietronero, L; Strässler, S

    2002-03-18

    The evidence for the key role of the sigma bands in the electronic properties of MgB2 points to the possibility of nonadiabatic effects in the superconductivity of these materials. These are governed by the small value of the Fermi energy due to the vicinity of the hole doping level to the top of the sigma bands. We show that the nonadiabatic theory leads to a coherent interpretation of T(c) = 39 K and the boron isotope coefficient alphaB = 0.30 without invoking very large couplings and it naturally explains the role of the disorder on T(c). It also leads to various specific predictions for the properties of MgB2 and for the material optimization of these types of compounds.

  2. Relaxation and pinning in spark-plasma sintered MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    Jirsa, M.; Rames, M.; Koblischka, M. R.; Koblischka-Veneva, A.; Berger, K.; Douine, B.

    2016-02-01

    The model of thermally activated relaxation developed and successfully tested on high-T c superconductors (Jirsa et al 2004 Phys. Rev. B 70 0245251) was applied to magnetic data of a bulk spark-plasma sintered MgB2 sample to elucidate its magnetic relaxation behavior. MgB2 and the related borides form a superconductor class lying between classical and high-T c superconductors. In accord with this classification, the relaxation phenomena were found to be about ten times weaker than in cuprates. Vortex pinning analyzed in terms of the field dependence of the pinning force density indicates a combined pinning by normal point-like defects and by grain surfaces. An additional mode of pinning at rather high magnetic fields (of still unknown origin) was observed.

  3. Comparison of Tunneling in Fe-based Superconductors with Multi-band MgB2

    NASA Astrophysics Data System (ADS)

    Zasadzinski, John; Iavarone, Maria

    MgB2 is an s-wave, phonon coupled, multiband superconductor that exhibits novel tunneling spectra including a subtle dip feature due to quasiparticle transfer between bands. Since this feature mimics the above-gap spectral dip feature observed in Fe-based superconductors, typically attributed to a strong coupling boson, it is worthwhile to consider whether quasiparticle transfer is relevant. We first show that the dip in MgB2 appears in the π-band, DOS (Δ = 2.4 meV) and is due to quasiparticle transfer to the σ-band with Δ = 7.2 meV. Reviewing the spectral dip in Fe-based superconductors, including new data on FeSe crystals, there are inconsistencies with quasiparticle transfer as the origin. The conclusion is that the spectral dip is more likely due to a boson, the resonance spin excitation, as found in cuprate superconductors.

  4. Magnetic relaxation induced by transverse flux shaking in MgB2 superconductors

    NASA Astrophysics Data System (ADS)

    Luzuriaga, J.; Badía-Majós, A.; Nieva, G.; Giordano, J. L.; López, C.; Serquis, A.; Serrano, G.

    2009-01-01

    We report on measurements and numerical simulations of the behavior of MgB2 superconductors when magnetic field components are applied along mutually perpendicular directions. By closely matching the geometry in simulations and measurements, full quantitative agreement is found. The critical state theory and a single phenomenological law, i.e. the field dependence of the critical current density Jc(B), are sufficient for a full quantitative description of the measurements. These were performed in thick strips of carbon nanotube doped MgB2 samples. Magnetization was measured in two orthogonal directions using a SQUID magnetometer. Magnetic relaxation effects induced by the application of an oscillatory perpendicular field were observed and simulated numerically. The measurements confirm the numerical predictions, that two relaxation regimes appear, depending on the amplitude of the applied magnetic field. The overall agreement constitutes a convincing validation of the critical state model and the numerical procedures used.

  5. Feasibility study of a MgB2 superconducting magnetic cloak

    DOE PAGES

    Giunchi, Giovanni; Turrioni, Daniele; Kashikhin, Vladimir; Nguyen, Hogan; Barzi, Emanuela

    2016-04-01

    The magnetic shielding capability of bulk MgB2 hollow cylinders can be fruitfully combined with an external paramagnetic sheath, to tailor the shape of the external magnetic flux lines. By appropriate selection of the external sheath permeability and thickness, it is possible to leave the magnetic flux lines unaltered by the shield (cloaking effect). Preliminary measurements have been performed at 4.2 K on shielding capability of bulk cylinders, which are subjected to axial and transversal magnetic fields up to 5 T. Furthermore, the cloaking conditions have been modeled to find the optimized thickness to realize the cloaking effect. The MgB2 materialmore » of the superconducting shield is also optimized to avoid low-temperature flux jumps, without losing its shielding capability.« less

  6. Mixed state of a dirty two-band superconductor: application to MgB2.

    PubMed

    Koshelev, A E; Golubov, A A

    2003-05-01

    We investigate the vortex state in a two-band superconductor with strong intraband and weak interband electronic scattering rates. Coupled Usadel equations are solved numerically, and the distributions of the pair potentials and local densities of states are calculated for two bands at different values of magnetic fields. The existence of two distinct length scales corresponding to different bands is demonstrated. The results provide qualitative interpretation of recent scanning tunneling microscopy experiments on vortex structure imaging in MgB2.

  7. Observation of Leggett's collective mode in a multiband MgB2 superconductor.

    PubMed

    Blumberg, G; Mialitsin, A; Dennis, B S; Klein, M V; Zhigadlo, N D; Karpinski, J

    2007-11-30

    We report observation of Leggett's collective mode in a multiband MgB2 superconductor with Tc=39 K arising from the fluctuations in the relative phase between two superconducting condensates. The novel mode is observed by Raman spectroscopy at 9.4 meV in the fully symmetric scattering channel. The observed mode frequency is consistent with theoretical considerations based on first-principles computations.

  8. Evidence for two-band superconductivity from break-junction tunneling on MgB2.

    PubMed

    Schmidt, H; Zasadzinski, J F; Gray, K E; Hinks, D G

    2002-03-25

    Superconductor-insulator-superconductor tunnel junctions have been fabricated on MgB2 that display Josephson and quasiparticle currents. These junctions exhibit a gap magnitude, Delta approximately 2.5 meV, that is considerably smaller than the BCS value, but which clearly and reproducibly closes near the bulk T(c). In conjunction with fits of the conductance spectra, these results are interpreted as direct evidence of two-band superconductivity.

  9. Raman scattering from a superconductivity-induced bound state in MgB2.

    PubMed

    Zeyher, R

    2003-03-14

    It is shown that the sharp peak in the E(2g) Raman spectrum of superconducting MgB2 is due to a bound state caused by the electron-phonon coupling. Our theory explains why this peak appears only in the spectra with E(2g) symmetry and only in the sigma but not the pi bands. The properties of the bound state and the Raman spectrum are investigated, also in the presence of impurity scattering.

  10. Effect of interband interactions on the pressure dependence on transition temperature of MgB2

    NASA Astrophysics Data System (ADS)

    Ogbuu, Okechukwu A.; Abah, Obinna

    2015-12-01

    A two-band BCS model with interactions, both phonon and non-phonon induced interactions, were employed to investigate the pressure dependence on superconducting transition temperature of two-band superconductor. We derived the transition temperature and its pressure dependence within Bogoliubov--Valatin formalism for magnesium diboride superconductor. We examined the influence of interband interactions on transition temperature at varying pressure and analyzed the relevance of this calculation in magnesium diboride, MgB2.

  11. Anisotropic normal-state properties of the MgB2 superconductor

    NASA Astrophysics Data System (ADS)

    de la Mora, Pablo; Castro, Miguel; Tavizon, Gustavo

    2005-02-01

    Based on the experimentally-found existence of two superconducting gaps in MgB2 (one gap associated to the boron σ-states and the other to the boron π-states), the different contributions to the transport properties, electrical conductivity and Hall coefficient were studied using the full potential-linearized augmented plane wave method and the generalized gradient approximation. Four different relaxation times were needed to adjust the electrical conductivity and Hall coefficient to experimental values. MgB2 doping was analysed in the rigid band approximation; this permitted a detailed study of the partial substitution of magnesium for aluminium (Mg1-xAlxB2). Other substitutions such as AB2 (A = Be, Sc, Zr, Nb and Ta) are also discussed. The MgB2 σ-bands (boron σ-states), which are associated to the large gap, are very anisotropic at EF, while the π bands have very little anisotropic character. In Mg1-xAlxB2, Tc diminishes with Al content; the other compounds are not superconductors or have a low Tc. In this work it was found that with electron doping, such as Al substitution, the σ-band conductivity decreases and the corresponding bands become less anisotropic. The σ-band contribution for BeB2 and ScB2 at EF is very small and the anisotropy is much lower. For Zr, Nb and Ta there are no σ-bands at EF. These results give a clear connection between superconductivity and the character of the σ-band, band conductivity, and band anisotropy. This gives a plausible explanation for the diminution of Tc with different doping of MgB2.

  12. Titania doping effect on superconducting properties of MgB2 bulk samples

    NASA Astrophysics Data System (ADS)

    Serrano, G.; Bridoux, G.; Serquis, A.

    2009-05-01

    In this work we study the microstructural and superconducting properties of doped and undoped bulk MgB2 samples prepared by solid-state reaction, with 0 and 2.5 %at. nominal TiO2 nanotubes contents, annealed at different temperatures in the 750-900°C range. We discuss the Tc, Jc and Hc2 performance and their correlation with the different synthesis parameters.

  13. Simulation of the impacts land use and land cover changes - LUCC on the hydrological response of the Ji-Parana Basin with MGB-INPE model

    NASA Astrophysics Data System (ADS)

    Rodriguez, D. A.; Tomasella, J.

    2012-04-01

    Hydrological response results from innumerous processes interacting at different spatial and temporal scales and with various intensities. Since the hydrological impacts of Land use and land cover change (LUCC) and climate variability (CV) are strongly dependent on soil water flow pathways, an adequate representation of the runoff generation mechanisms are crucial to assess the hydrological impacts of LUCC and CV on a basin scale. Model responses to LUCC depend on structure and parameterizations used in the model. There are two basic methodologies adopted to define the structure of the hydrological model: downward and upward approaches. Upward approach is more appropriate for identifying causal relationships, but their results are highly affected by assumptions used in the development of the model. Besides, model structure and parameters values definition are strongly affected by scale issues and their inter-relationships. Downward approach is more appropriate for studying the effects of LUCC, but casual relationships are more difficult to identify. MGB-INPE model was developed based on the Large Scale Basins Model of Brazilian Institute of Hydraulic Research (MGB-IPH). It uses the Xinanjiang Model approach for soil water capacity distribution at each cell combined with TopModel philosophy. Both methodologies follow a downward approach: the hydrologic response of the basin is associated with patterns of self-organization observed at the basin-scale. The model was applied in the Ji-Parana Basin (JPB), a 30.000-km2 basin in the SW Amazonia. The JPB is part of the Deforestation Arc of Amazonia in Brazil and it has lost more than 50 % of his forest cover since the 80's. Simulations were performed between 1982 and 2005 considering annual land use and land cover change. MGB-INPE model was able to represent the impact of LUCC in the runoff generation process and its dependence with basin topography. Simulation results agree with observational studies: LUCC impacts in fast

  14. Enhancement of the in-field Jc of MgB2 via SiCl4 doping

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Lin; Dou, S. X.; Hossain, M. S. A.; Cheng, Z. X.; Liao, X. Z.; Ghorbani, S. R.; Yao, Q. W.; Kim, J. H.; Silver, T.

    2010-06-01

    We present the following results. (1) We introduce a doping source for MgB2 , liquid SiCl4 , which is free of C, to significantly enhance the irreversibility field (Hirr) , the upper critical field (Hc2) , and the critical current density (Jc) with a little reduction in the critical temperature (Tc) . (2) Although Si can not be incorporated into the crystal lattice, a significant reduction in the a -axis lattice parameter was found, to the same extent as for carbon doping. (3) Based on the first-principles calculation, it is found that it is reliable to estimate the C concentration just from the reduction in the a -lattice parameter for C-doped MgB2 polycrystalline samples that are prepared at high sintering temperatures, but not for those prepared at low sintering temperatures. Strain effects and magnesium deficiency might be reasons for the a -lattice reduction in non-C or some of the C-added MgB2 samples. (4) The SiCl4 -doped MgB2 shows much higher Jc with superior field dependence above 20 K compared to undoped MgB2 and MgB2 doped with various carbon sources. (5) We introduce a parameter, RHH (Hc2/Hirr) , which can clearly reflect the degree of flux-pinning enhancement, providing us with guidance for further enhancing Jc . (6) It was found that spatial variation in the charge-carrier mean free path is responsible for the flux-pinning mechanism in the SiCl4 treated MgB2 with large in-field Jc .

  15. Effect of heating rates on microstructure and superconducting properties of pure MgB 2

    NASA Astrophysics Data System (ADS)

    Zhao, Qian; Liu, Yongchang; Han, Yajing; Ma, Zongqing; Shi, Qingzhi; Gao, Zhiming

    2009-07-01

    The influence of different heating rates, ranging from 5 to 30 K min -1, on the microstructure and superconducting of the MgB 2 bulk was investigated. No obvious variation in the grain size was found for the samples heated from 5 K min -1 to 20 K min -1 except for the changes in morphologies. Moreover, the grain refinement was obtained under the heating rate of 30 K min -1. The critical current density ( Jc) suggested that the 5 K min -1 sample had the best performance in high field. Here, the differential thermal analysis (DTA) was employed to analyze the kinetics of MgB 2 phase formation with the different heating rates. The results showed that the large amount of MgB 2 formed at low temperature, which lead to compact structures under the slow heating rate. The fast heating rate would promote the evaporation of Mg at high temperature, which was considered to generate the vacancy and impurities in the sample.

  16. Flux jumps in high-J c MgB2 bulks during pulsed field magnetization

    NASA Astrophysics Data System (ADS)

    Fujishiro, H.; Mochizuki, H.; Naito, T.; Ainslie, M. D.; Giunchi, G.

    2016-03-01

    Pulsed field magnetization (PFM) of a high-J c MgB2 bulk disk has been investigated at 20 K, in which flux jumps frequently occur for high pulsed fields. Using a numerical simulation of the PFM procedure, we estimated the time dependence of the local magnetic field and temperature during PFM. We analyzed the electromagnetic and thermal instability of the high-J c MgB2 bulk to avoid flux jumps using the time dependence of the critical thickness, d c(t), which shows the upper safety thickness to stabilize the superconductor magnetically, and the minimum propagation zone length, l m(t), to obtain dynamical stability. The values of d c(t) and l m(t) change along the thermally-stabilized direction with increasing temperature below the critical temperature, T c. However, the flux jump can be qualitatively understood by the local temperature, T(t), which exceeds T c in the bulk. Finally, possible solutions to avoid flux jumps in high-J c MgB2 bulks are discussed.

  17. l/f Noise in the Superconducting Transition of a MgB2 Thin Film

    NASA Technical Reports Server (NTRS)

    Lakew, B.; Aslam, S.; Jones, H.; Stevenson, T.; Cao, N.

    2010-01-01

    The noise voltage spectral density in the superconducting transition of a MgB2 thin film on a SiN-coated Si thick substrate was measured over the frequency range 1 Hz-to-1 KHz. Using established bolometer noise theory the theoretical noise components due to Johnson, 1/f(excess) and phonon noise are modeled to the measured data. It is shown that for the case of a MgB2 thin film in the vicinity of the mid-point of transition, coupled to a heat sink via a fairly high thermal conductance (approximately equal to 10(sup -1) W/K)) that the measured noise voltage spectrum is 1/f limited and exhibits lit dependence with a varying between 0.3 and 0.5 in the measured frequency range. At a video frame rate frequency of 30 Hz the measured noise voltage density in the film is approximately equal to 61 nV /the square root of HZ, using this value an upper limit of electrical NEP approximately equal to 0.67pW / the square root of Hz is implied for a practical MgB2 bolometer operating at 36.1 K.

  18. Phonon modes of MgB2: super-lattice structures and spectral response.

    PubMed

    Alarco, Jose A; Chou, Alison; Talbot, Peter C; Mackinnon, Ian D R

    2014-11-28

    Micrometre-sized MgB2 crystals of varying quality, synthesized at low temperature and autogenous pressure, are compared using a combination of Raman and infra-red (IR) spectroscopy. These data, which include new peak positions in both spectroscopies for high quality MgB2, are interpreted using DFT calculations on phonon behaviour for symmetry-related structures. Raman and IR activity additional to that predicted by point group analyses of the P6/mmm symmetry are detected. These additional peaks, as well as the overall shapes of calculated phonon dispersion (PD) models are explained by assuming a double super-lattice, consistent with a lower symmetry structure for MgB2. A 2× super-lattice in the c-direction allows a simple correlation of the pair breaking energy and the superconducting gap by activation of corresponding acoustic frequencies. A consistent physical interpretation of these spectra is obtained when the position of a phonon anomaly defines a super-lattice modulation in the a-b plane.

  19. Ab initio investigation of the electronic and geometric structure of magnesium diboride, MgB2.

    PubMed

    Tzeli, Demeter; Mavridis, Aristides

    2005-12-01

    Employing multireference variational (MRCI) and coupled cluster (CC) methods combined with quadruple-zeta quality correlation-consistent basis set, we have studied 36 states of the magnesium diboride (MgB(2)) molecule as well as 17 states of the experimentally unknown diatomic MgB. For all states of MgB(2), we report geometries, atomization energies, and dipole moments, while for the first 5 states, potential energy profiles have been also constructed. The ground state is formally of (1)A(1) V-shaped symmetry with an atomization energy of 108.1(109) kcal/mol at the MRCI(MRCI + Davidson correction) level. The first excited state ((3)B(1)) is less than 1 kcal/mol above the X(1)A(1) state, with the next state of linear Mg-B-B geometry (b(3)Sigma(-)) located 10 kcal/mol higher. In all states, bent or linear, the bonding is complicated and unconventional because of the extraordinary bonding agility of the boron atom(s).

  20. High-pressure synthesis of pure and doped superconducting MgB2 compounds

    NASA Astrophysics Data System (ADS)

    Toulemonde, P.; Musolino, N.; Flükiger, R.

    2003-02-01

    Superconducting properties of bulk, dense, pure MgB2 and doped (Mg1-xAx)B2 samples with A = Na, Ca, Cu, Ag, Zn and Al were studied for compositional ranges 0 < x leq 0.20. The effects on pinning properties and critical current were investigated, particularly for A = aluminium. The samples were sintered and/or synthesized at high pressure-high temperature in a cubic multi-anvil press (typically 3.5-6 GPa, 900-1000 °C). They were characterized by x-ray diffraction, scanning electron microscopy and their superconducting properties were investigated by ac susceptibility, magnetization (VSM and SQUID) and transport measurements under a magnetic field. Only Al really substitutes on the Mg site. The other elements form secondary phases with B or Mg which do not act as pinning centres. No positive effect is observed on the superconducting properties of the bulk MgB2 samples with these doping elements added: Tc, critical current jc, Hirr and Hc2. For Al, the effect on Hc2 remains small, and the irreversibility line does not move, thus not improving the critical current of the Al-doped MgB2 samples.

  1. Full scale field test of the in situ air stripping process at the Savannah River integrated demonstration test site

    SciTech Connect

    Looney, B.B.; Hazen, T.C.; Kaback, D.S.; Eddy, C.A.

    1991-06-29

    Under sponsorship from the US Department of Energy, technical personnel from the Savannah River Laboratory (SRL) and other DOE laboratories, universities and private industry have completed a full scale demonstration of environmental remediation using horizontal wells. This demonstration was performed as Phase I of an Integrated Demonstration Project designed to evaluate innovative remediation technologies for environmental restoration of sites contaminated with organic contaminants. The demonstration utilized two directionally drilled horizontal wells to deliver gases and extract contaminants from the subsurface. The resulting in situ air stripping process was designed to remediate soils and sediments above and below the water table as well as groundwater contaminated with volatile organic contaminants. The 139 day long test successfully removed volatile chlorinated solvents from the subsurface using the two horizontal wells. One well, approximately 300 ft (90m) long and 165 ft (50m) deep drilled below a contaminant plume in the groundwater, was used to inject air and strip the contaminants from the groundwater. A second horizontal well, approximately 175 ft (53m) long and 75 ft (23m) deep in the vadose zone, was used to extract residual contamination in the vadose zone along with the material purged from the groundwater. Pretest and posttest characterization data and monitoring data during the demonstration were collected to aid in interpretation of the test and to provide the information needed for future environmental restoration that employ directionally drilled wells as extraction or delivery systems. Contaminant concentration data and microbiological monitoring data are summarized in this report; the characterization data and geophysical monitoring data are documented in a series of related project reports.

  2. Data processing and preliminary results of the Chang'e-3 VIS/NIR Imaging Spectrometer in-situ analysis

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Li, Chun-Lai; Zhang, Guang-Liang; Xu, Rui; Liu, Jian-Jun; Ren, Xin; Tan, Xu; Zhang, Xiao-Xia; Zuo, Wei; Wen, Wei-Bin

    2014-12-01

    The Chang'e-3 Visible and Near-infrared Imaging Spectrometer (VNIS) is one of the four payloads on the Yutu rover. After traversing the landing site during the first two lunar days, four different areas are detected, and Level 2A and 2B radiance data have been released to the scientific community. The released data have been processed by dark current subtraction, correction for the effect of temperature, radiometric calibration and geometric calibration. We emphasize approaches for reflectance analysis and mineral identification for in-situ analysis with VNIS. Then the preliminary spectral and mineralogical results from the landing site are derived. After comparing spectral data from VNIS with data collected by the M3 instrument and samples of mare that were returned from the Apollo program, all the reflectance data have been found to have similar absorption features near 1000 nm except lunar sample 71061. In addition, there is also a weak absorption feature between 1750~2400 nm on VNIS, but the slopes of VNIS and M3 reflectance at longer wavelengths are lower than data taken from samples of lunar mare. Spectral parameters such as Band Centers and Integrated Band Depth Ratios are used to analyze mineralogical features. The results show that detection points E and N205 are mixtures of high-Ca pyroxene and olivine, and the composition of olivineat point N205 is higher than that at point E, but the compositions of detection points S3 and N203 are mainly olivine-rich. Since there are no obvious absorption features near 1250 nm, plagioclase is not directly identified at the landing site.

  3. Calibrating IR Cameras for In-Situ Temperature Measurement During the Electron Beam Melting Process using Inconel 718 and Ti-Al6-V4

    SciTech Connect

    Dinwiddie, Ralph Barton; Lloyd, Peter D; Dehoff, Ryan R; Lowe, Larry E

    2016-01-01

    The Department of Energy s (DOE) Manufacturing Demonstration Facility (MDF) at Oak Ridge National Laboratory (ORNL) provides world-leading capabilities in advanced manufacturing (AM) facilities which leverage previous, on-going government investments in materials science research and characterization. MDF contains systems for fabricating components with complex geometries using AM techniques (i.e. 3D-Printing). Various metal alloy printers, for example, use electron beam melting (EBM) systems for creating these components which are otherwise extremely difficult- if not impossible- to machine. ORNL has partnered with manufacturers on improving the final part quality of components and developing new materials for further advancing these devices. One method being used to study (AM) processes in more depth relies on the advanced imaging capabilities at ORNL. High performance mid-wave infrared (IR) cameras are used for in-situ process monitoring and temperature measurements. However, standard factory calibrations are insufficient due to very low transmissions of the leaded glass window required for X-ray absorption. Two techniques for temperature calibrations will be presented and compared. In-situ measurement of emittance will also be discussed. Ample information can be learned from in-situ IR process monitoring of the EBM process. Ultimately, these imaging systems have the potential for routine use for online quality assurance and feedback control.

  4. Investigation of the feasibility of recovering energy from Antrim oil shale by an in situ process. Final summary report

    SciTech Connect

    Young, D.C.

    1980-09-01

    This report briefly summarizes the results of a four-year study which consisted of four tasks: shale characterization; in-situ fracturing and assessment; in situ extraction trails; and environmental, public policy and legal assessment. Forty one topical reports issued during the project are listed. A wealth of data has been published on the chemical, physical, geological, mineralogical and lithological properties of Antrim shale. Large numbers of stratigraphic cross sections and maps have been prepared. Much was learned in the fracturing experiments and extraction trials. Antrim shale was successfully ignited in situ in an explosively fractured site and low BTU gas was produced. However, as the formation was heated up the permeability decreased, and significant self sustained combustion was not achieved before work had to be discontinued. No significant impacts on the environment other than surface disturbance were observed.

  5. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    SciTech Connect

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-15

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  6. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes.

    PubMed

    Wiesinger, R; Schade, U; Kleber, Ch; Schreiner, M

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  7. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    NASA Astrophysics Data System (ADS)

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  8. Mining nitrate concentration patterns from high-frequency in situ monitoring: a step towards more detailed understanding of hydrological processes?

    NASA Astrophysics Data System (ADS)

    Aubert, Alice; Houska, Tobias; Plesca, Ina; Kraft, Philipp; Breuer, Lutz

    2015-04-01

    Recently developed sensing technics allow collecting a considerable amount of high-frequency data; not only for hydrologic parameters (water levels, rainfall, etc.) but also for water chemistry. With devices such as in situ spectrophotometer, nitrate concentration can be monitored down to sub-hourly intervals. Thus, opening the way to new questions: what about daily or sub-daily instream nitrate concentration variations? What do these newly observed variations tell us about hydrological processes? In the Vollnkirchener Bach catchment, a headwater creek flows through a human impacted landscape dominated by agricultural and forest use and including a small settlement. Since March 2013, a Pro-PS device has been installed at the gauging station (monitored since 2011). Nitrate concentration is measured every 15 minutes, discharge and water temperature every 5 minutes. Data mining, more precisely motif discovery, is performed on these time series to identify high-resolution patterns. Spectral analysis highlighted that, in data measured at sub-hourly sampling frequency, variations up to a few hours are more likely to be dominated by measurement noise rather than real-world fluctuations. Therefore, we focus on daily motifs and flood patterns (given the fact that hydrological conditions are changing during flood events, we assume that nitrate concentration changes are depicting real processes). Various flood motifs were extracted: (1) nitrate can either be diluted or (2) concentrated, or (3) both (dilution followed by a bumpy recession curve indicating nitrate enrichment at the end of the flood). In addition to these classical nutrient-discharge behaviors, a variety of other interesting motifs were highlighted. (4) A daily nitrate cycle is clearly observed, but only during a specific year period. (5) Lag to peak time between parameters differentiate flood patterns: sometimes nitrate peaks first, sometimes discharge peaks first. (6) Furthermore, we are able to pinpoint the

  9. Fault and anthropogenic processes in central California constrained by satellite and airborne InSAR and in-situ observations

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Lundgren, Paul

    2016-07-01

    , but are subject to severe decorrelation. The L-band ALOS and UAVSAR SAR sensors provide improved coherence compared to the shorter wavelength radar data. Joint analysis of UAVSAR and ALOS interferometry measurements show clear variability in deformation along the fault strike, suggesting variable fault creep and locking at depth and along strike. Modeling selected fault transects reveals a distinct change in surface creep and shallow slip deficit from the central creeping section towards the Parkfield transition. In addition to fault creep, the L-band ALOS, and especially ALOS-2 ScanSAR interferometry, show large-scale ground subsidence in the SJV due to over-exploitation of groundwater. Groundwater related deformation is spatially and temporally variable and is composed of both recoverable elastic and non-recoverable inelastic components. InSAR time series are compared to GPS and well-water hydraulic head in-situ time series to understand water storage processes and mass loading changes. We are currently developing poroelastic finite element method models to assess the influence of anthropogenic processes on surface deformation and fault mechanics. Ongoing work is to better constrain both tectonic and non-tectonic processes and understand their interaction and implication for regional earthquake hazard.

  10. Highly sensitive detection of the MGB1 transcript (mammaglobin) in the peripheral blood of breast cancer patients.

    PubMed

    Cerveira, Nuno; Torres, Lurdes; Rocha, Patrícia; Bizarro, Susana; Pereira, Deolinda; Abreu, Joaquim; Henrique, Rui; Teixeira, Manuel R; Castedo, Sérgio

    2004-02-10

    We describe a new one-step RT-PCR assay for the detection of the mammaglobin (MGB1) gene transcript in the peripheral blood of breast cancer patients. With this approach, the MGB1 transcript could be detected in the peripheral blood of 22 of 54 (41%) breast cancer patients prior to any therapy. This method, using specific primers for cDNA synthesis, proved to be more sensitive (10(-6) to 10(-11), usually 10(-7)) than previously reported methodologies. This increased sensitivity was achieved without compromising specificity, as the MGB1 transcript was not detected in 38 blood samples of healthy donors and in only 1 of 18 blood samples of patients presenting with hematologic malignancies. A positive correlation was seen between MGB1 positivity and breast cancer stage: 0/3 (0%) in stage 0, 3/13 (23%) in stage I, 6/17 (35%) in stage II, 5/10 (50%) in stage III, 8/11 (73%) in stage IV (p = 0.003). The prognostic and therapeutic implications of MGB1 positivity by one-step RT-PCR in the peripheral blood of breast cancer patients, especially in clinically localized disease (stages I and II), should be evaluated after long-term clinical follow-up of these patients. PMID:14696125

  11. Effects of aqueous effluents from in situ fossil fuel processing technologies on aquatic systems. Annual progress report, January 1-December 31, 1979

    SciTech Connect

    Bergman, H.L.

    1980-01-04

    This is the third annual progress report for a continuing EPA-DOE jointly funded project to evaluate the effects of aqueous effluents from in situ fossil-fuel processing technologies on aquatic biota. The project is organized into four project tasks: (1) literature review; (2) process water screening; (3) methods development; and (4) recommendations. Our Bibliography of aquatic ecosystem effects, analytical methods and treatment technologies for organic compounds in advanced fossil-fuel processing effluents was submitted to the EPA for publication. The bibliography contains 1314 citations indexed by chemicals, keywords, taxa and authors. We estimate that the second bibliography volume will contain approximately 1500 citations and be completed in February. We compiled results from several laboratories of inorganic characterizations of 19 process waters: 55 simulated in situ oil-shale retort waters; and Hanna-3, Hanna-4B 01W and Lawrence Livermore Hoe Creek underground coal gasification condenser waters. These process waters were then compared to a published summary of the analyses from 18 simulated in situ oil-shale retort waters. We completed this year 96-h flow-through toxicity bioassays with fathead minnows and rainbow trout and 48-h flow-through bioassays with Daphnia pulicaria exposed to 5 oil-shale process waters, 1 tar-sand process water, 2 underground coal gasification condenser waters, 1 post-gasification backflood condenser water, as well as 2 bioassays with fossil-fuel process water constituents. The LC/sub 50/ toxicity values for these respective species when exposed to these waters are given in detail. (LTN)

  12. Environmental survey - tar sands in situ processing research program (Vernal, Uintah County, Utah). [Reverse-forward combustion; steam injection

    SciTech Connect

    Skinner, Q.

    1980-03-01

    Research will be done on the reverse-forward combustion and steam injection for the in-situ recovery of oil from tar sands. This environmental survey will serve as a guideline for the consideration of environmental consequences of such research. It covers the construction phase, operational phase, description of the environment, potential impacts and mitigations, coordination, and alternatives. (DLC)

  13. Detection of numerical chromosome aberrations using in situ hybridization in paraffin sections of routinely processed bladder cancers.

    PubMed

    Hopman, A H; van Hooren, E; van de Kaa, C A; Vooijs, P G; Ramaekers, F C

    1991-07-01

    An improved protocol for in situ hybridization (ISH) to routinely processed, paraffin-imbedded tissue sections from transitional bladder carcinoma (TCC) is presented. The protocol to detect numerical chromosome aberrations involved treatment of sections with thiocyanate prior to proteolytic digestion, resulting in reproducible ISH reactions. It was used to explore the influence of nuclear truncation in the detection of numerical chromosome aberrations and the detection of tumor cells among stromal and inflammatory cells, to compare the flow cytometric DNA index with chromosome copy number, and to study chromosome heterogeneity within tumors. For this study, a DNA probe for the chromosome region 1q12 was used. Hybridization of model systems with known chromosome numbers, such as sections of paraffin-embedded lymph nodes, paraffin-embedded human peripheral lymphocytes, T24 and Molt-4 cells with two, three, and four chromosomes 1, respectively, showed in at least 50% of the cells the proper number of chromosome hybridization signals in standard 6-microns-thick sections. Depending on the size of the nucleus, a certain percentage of the cells showed lower copy numbers as a result of truncation. In four cases of normal urothelium in paraffin sections, the percentage of nuclei with more than two chromosome spots did not exceed 5%. Comparison of the number of ISH signals, as detected in ethanol-fixed single cell suspensions of 11 TCCs [five flow cytometric (FCM) diploid, three FCM aneuploid, and three FCM tetraploid], with ISH results obtained in paraffin sections of the same tumors showed that typical numerical chromosome aberrations, such as trisomy and tetrasomy up to nonasomy, could be detected. However, the real chromosome copy number is underestimated, especially in tumors with high copy numbers, as detected in the single cell suspensions of the same tumors. Hybridization of a TCC with extremely large nuclei (DNA index = 3.2) containing six to nine ISH signals as

  14. Influence of Surface Sorption Processes on Spectral Induced Polarization Evaluated Using in-Situ Monitoring of a Na-22 Tracer

    NASA Astrophysics Data System (ADS)

    Hao, N.; Moysey, S. M.; Powell, B. A.; Ntarlagiannis, D.

    2014-12-01

    Spectral Induced Polarization (SIP) has been used to monitor subsurface biogeochemical processes in a variety of lab and field studies. However, there are several competing mechanisms that have been proposed to explain the SIP effect. This work targets the influence of ion sorption to mineral surfaces as a controlling factor on SIP utilizing a pH dependent surface adsorption experiment. In this experiment we use silica gel as an idealized medium where the number of available sites for cation sorption, which in this case is limited to Na+ and H+ ions, is influenced by changes in pH via protonation/deprotonation of silanol groups. The experiment uses 22Na as an in situ tracer as the radioactive decay of this nuclide can be continuously and non-invasively monitored using sensors placed outside of a column. The experiment was conducted by continuously pumping a 0.01M NaCl solution spiked with of 1μCi/L 22Na in to the column under three pH conditions (pH 5.0, 6.0 and 8.0). In the experiment, we observed an increasing number of gamma counts caused by the accumulation of sorbed 22Na in the column as we increased the pH from 5.0 to 6.5, and finally to 8.0. Simultaneously, we observed a linearly correlated (R2 = 0.99) rise in the imaginary conductivity response of the SIP measurements. Using the triple layer electrochemical polarization model for grain polarization to simulate our experimental SIP responses, we found that the estimated surface site density is within a factor of two of that estimated from the mass accumulation of sodium. Since the accumulation of sodium on the silica gel surface is responsible for both the increase in gamma radiation and the change in the electrical response, these observations support the theory that mobile ions in the Stern layer of mineral surfaces provide the primary control on SIP signals in silicate materials.

  15. Analysis of the levitation force of pure and starch/polystyrene/MWCNT added bulk MgB2 superconductors using frozen image model under zero field cooling condition

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Dey, T. K.

    2016-04-01

    The measurement of superconducting levitation force between permanent magnet and polycrystalline samples of pure and MgB2 added with starch, polystyrene (PS) and multiwall carbon nanotube (MWCNT) have been performed under zero field cooling (ZFC) condition at 20 K in both descending and ascending modes. For this, the bulk pellets were synthesized by conventional solid state sintering technique. The XRD data indicate well developed MgB2 phase. However, a decrease in lattice parameter 'a = b' have been observed for doped MgB2 samples. Superconducting transition temperature of MgB2 also decreases with starch/PS/MWCNT addition. Unlike MWCNT, the addition of starch/polystyrene is found to enhance the levitation force of MgB2 superconductor. The levitation force between PM and investigated pellets in ZFC condition is explained well in terms of the updated version of modified frozen image model and the magnetic moment originated due to vertical motion of the superconductors have been estimated. It may be noted that except for MWCNT, addition of starch/PS in MgB2 improves the magnetic moment generated by vertical movement of pure MgB2. However, this improvement is more pronounced for 1 wt.% of PS added MgB2, which indicates more flux trapping and hence better levitation properties in 1 wt.% of PS added MgB2. The vertical stiffness estimated for pure and starch/PS/MWCNT doped MgB2 samples indicate that the levitation force are more sensitive in the region close to the PM.

  16. In situ investigation of titanium nitride surface dynamics: The role of surface and bulk mass transport processes

    NASA Astrophysics Data System (ADS)

    Bareno, Javier

    NaCl-structure TiN and related transition-metal (TM) nitrides are widely used as hard wear-resistant coatings on cutting tools, diffusion-barriers in microelectronic devices, corrosion-resistant layers on mechanical components, and abrasion-resistant thin films on optics and architectural glass. Since the elastic and physical properties of TiN are highly anisotropic, controlling the microstructural and surface morphological evolution of polycrystalline TM nitride films is important for all of the above applications. In this thesis, I used in-situ high-temperature low-energy electron microscopy (LEEM) to gain insight into film growth and microstructure development dynamics by studying mass-transport processes occurring during annealing of three dimensional (3D) structures on TiN surfaces. Additionally, in order to extend the current understanding of nanostructure development in binary nitride films to more complex ternary TM-nitride-based nanocomposites, I employed in-situ scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED), as well as ab-initio modeling, to investigate the atomic structure of the SiNx/TiN heterointerfaces which control the properties of SiNx-TiN nanocomposites. The LEEM studies of mass transport on TiN(111) focus on two specific surface morphologies which are observed to be present during growth of TiN single-crystals. (1) I investigated the temperature-dependent coarsening/decay kinetics of three-dimensional TiN island mounds on large (>1000 A) atomically-flat terraces; showing that TiN(111) steps are highly permeable and exhibit strong repulsive temperature-dependent step-step interactions that vary from 0.03 eV-A at 1559 K to 0.76 eV-A at 1651 K. (2) I studied the nucleation and growth of spiral steps originating at surface-terminated screw dislocations; I developed a model of spiral growth relating the emission rate of point defects from the bulk to the temperature-dependent spiral rotation frequency o(T); and I

  17. Enhancement at low temperatures of the critical current density for Au-coated MgB2 thin films

    NASA Astrophysics Data System (ADS)

    Choi, Eun-Mi; Lee, Hyun-Sook; Kim, Heon-Jung; Lee, Sung-Ik; Kim, Hyeong-Jin; Kang, W. N.

    2004-01-01

    We measured the superconducting critical current densities (Jc) from the magnetization hysteresis (M-H) loop for Au-coated MgB2 thin films. The purpose of this experiment was to determine whether the vortex avalanche phenomenon which suppresses the Jc for low temperature (T<15 K) and low field (H⩽1000 Oe) could be cured by gold deposition. This avalanche, called flux noise, has been a headache in applications of MgB2 thin films. Fortunately, the flux noise in the M-H loop is suppressed with increasing Au-film thickness and finally disappears when the thickness of the gold becomes 2.55 μm. We found a way to remove one obstacle for applications of MgB2 thin films as an superconducting device.

  18. Enhancement of low temperature Critical current density of MgB2 thin films by Au coating

    NASA Astrophysics Data System (ADS)

    Choi, Eun-Mi; Lee, Hyun-Sook; Kim, Heon-Jung; Lee, Sung-Ik; Kim, Hyeong-Jin; Kang, W. N.

    2004-03-01

    We measured the superconducting critical current densities (J_c) from the magnetization hysteresis (M-H) loop while depositing the gold on top of the MgB2 thin film. The purpose of this experiment is whether the vortex avalanche phenomena which suppress the Jc for low temperature ( T < 15 K ) and low field (H ≤ 1000 Oe) can be cured by gold deposition. This avalanche called flux noise has been headache for the application of the MgB2 thin films. As increasing the thickness of Au film, fortunately, the flux noise in the M-H loop is suppressed and finally disappears when thickness of the gold becomes 2.55 ¥im. From this experiment, the obstacles of the application of MgB2 thin film are completely overcome

  19. Vortex flux pinning mechanism and enhancement of in-field Jc in succinic acid doped MgB2

    NASA Astrophysics Data System (ADS)

    Ghorbani, S. R.; Darini, M.; Wang, X. L.; Hossain, M. S. A.; Dou, S. X.

    2013-08-01

    The field dependence of the resistivity and the critical current density, Jc(B), of MgB2 doped with 10 wt% wet and dry succinic acid have been investigated by magnetic measurements. The dry succinic acid significantly enhanced the upper critical field, the irreversibility field, and the Jc(B) compared to the wet succinic acid doped MgB2 and the pure MgB2. The field dependence of Jc(B) was analyzed within the collective pinning model. The observed temperature dependence of the crossover field, Bsb(T), from the single vortex to the small vortex bundle pinning regime shows that flux pinning arising from variation in the critical temperature, δTc, is the dominant mechanism for the wet sample over the whole studied temperature range, while there is a competition between δTc pinning and the pinning from variation in the mean free path, δl, for the dry sample.

  20. Investigations of current limiting properties of the MgB2 wires subjected to pulse overcurrents in the benchtop tester

    NASA Astrophysics Data System (ADS)

    Ye, Lin; Majoros, M.; Campbell, A. M.; Coombs, T.; Harrison, S.; Sargent, P.; Haslett, M.; Husband, M.

    2007-04-01

    A laboratory scale desktop test system including a cryogenic system, an AC pulse generation system and a real time data acquisition program in LabView/DAQmx, has been developed to evaluate the quench properties of MgB2 wires as an element in a superconducting fault current limiter under pulse overcurrents at 25 K in self-field conditions. The MgB2 samples started from a superconducting state and demonstrated good current limiting properties characterized by a fast transition to the normal state during the first half of the cycle and a continuously limiting effect in the subsequent cycles without burnouts. The experimental and numerical simulation results on the quench behaviour indicate the feasibility of using MgB2 for future superconducting fault current limiter (SFCL) applications. This work is supported by Rolls-Royce Plc and the UK Department of Trade & Industry (DTI).