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Sample records for hastelloy n

  1. Hemispherical total emissivity of Hastelloy N with different surface conditions

    NASA Astrophysics Data System (ADS)

    Gordon, Andrew J.; Walton, Kyle L.; Ghosh, Tushar K.; Loyalka, Sudarshan K.; Viswanath, Dabir S.; Tompson, Robert V.

    2012-07-01

    The hemispherical total emissivity of Hastelloy N (a candidate structural material for Next Generation Nuclear Plants (NGNPs), particularly for the molten fluoride cooled reactors) was measured using an experimental set-up that was constructed in accordance with the standard ASTM C835-06. The material surface conditions included: (i) 'as received' (original) sample from the supplier; (ii) samples with increased surface roughness through sand blasting; (iii) oxidized surface, and (iv) samples coated with graphite powder. The emissivity of the as received samples varied from around 0.22 to 0.28 in the temperature range of 473 K to 1498 K. The emissivity increased when the roughness of the surface increased compared to an as received sample. When Hastelloy N was oxidized in air at 1153 K or coated with graphite powder, its emissivity increased substantially. The sample sand blasted with 60 grit beads and sprinkled with graphite powder showed an increase of emissivity from 0.2 to 0.60 at 473 K and from 0.25 to 0.67 at 1473 K. The oxidized surface showed a similar behavior: an increase in emissivity compared to an unoxidized sample. This increase in emissivity has strong favorable safety implications in terms of decay heat removal in post-accident environments. The data were compared with another Hastelloy family member, Hastelloy X.

  2. Long-term corrosion behaviors of Hastelloy-N and Hastelloy-B3 in moisture-containing molten FLiNaK salt environments

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Chang, Chi-Hung; Kai, Ji-Jung

    2014-03-01

    This study investigated long-term corrosion behaviors of Ni-based Hastelloy-N and Hastelloy-B3 under moisture-containing molten alkali fluoride salt (LiF-NaF-KF: 46.5-11.5-42%) environment at an ambient temperature of 700 °C. The Hastelloy-N and Hastelloy-B3 experienced similar weight losses for tested duration of 100-1000 h, which was caused by aggregate dissolution of Cr and Mo into FLiNaK salts. The corrosion rate of both alloys was high initially, but then reduced during the course of the test. The alleviated corrosion rate was due to the depletion of Cr and Mo near surface of the alloys and thus the long-term corrosion rate was controlled by diffusion of Cr and Mo outward to the alloy surface. The results of microstructural characterization revealed that the corrosion pattern for both alloys tended to be intergranular corrosion at early stage of corrosion test, and then transferred to general corrosion for longer immersion hours.

  3. ERDA, RBS, TEM and SEM characterization of microstructural evolution in helium-implanted Hastelloy N alloy

    NASA Astrophysics Data System (ADS)

    Gao, Jie; Bao, Liangman; Huang, Hefei; Li, Yan; Lei, Qiantao; Deng, Qi; Liu, Zhe; Yang, Guo; Shi, Liqun

    2017-05-01

    Hastelloy N alloy was implanted with 30 keV, 5 × 1016 ions/cm2 helium ions at room temperature, and subsequent annealed at 600 °C for 1 h and further annealed at 850 °C for 5 h in vacuum. Using elastic recoil detection analysis (ERDA) and transmission electron microscopy (TEM), the depth profiles of helium concentration and helium bubbles in helium-implanted Hastelloy N alloy were investigated, respectively. The diffusion of helium and molybdenum elements to surface occurred during the vacuum annealing at 850 °C (5 h). It was also observed that bubbles in molybdenum-enriched region were much larger in size than those in deeper region. In addition, it is worth noting that plenty of nano-holes can be observed on the surface of helium-implanted sample after high temperature annealing by scanning electron microscope (SEM). This observation provides the evidence for the occurrence of helium release, which can be also inferred from the results of ERDA and TEM analysis.

  4. Ion irradiation-induced swelling and hardening effect of Hastelloy N alloy

    NASA Astrophysics Data System (ADS)

    Zhang, S. J.; Li, D. H.; Chen, H. C.; Lei, G. H.; Huang, H. F.; Zhang, W.; Wang, C. B.; Yan, L.; Fu, D. J.; Tang, M.

    2017-06-01

    The volumetric swelling and hardening effect of irradiated Hastelloy N alloy were investigated in this paper. 7 MeV and 1 MeV Xe ions irradiations were performed at room temperature (RT) with irradiation dose ranging from 0.5 to 27 dpa. The volumetric swelling increases with increasing irradiation dose, and reaches up to 3.2% at 27 dpa. And the irradiation induced lattice expansion is also observed. The irradiation induced hardening initiates at low ion dose (≤1dpa) then saturates with higher ion dose. The irradiation induced volumetric swelling may be ascribed to excess atomic volume of defects. The irradiation induced hardening may be explained by the pinning effect where the defects can act as obstacles for the free movement of dislocation lines. And the evolution of the defects' size and number density could be responsible for the saturation of hardness.

  5. Effects of Sputtering Parameters on AlN Film Growth on Flexible Hastelloy Tapes by Two-Step Deposition Technique

    PubMed Central

    Peng, Bin; Gong, Dongdong; Zhang, Wanli; Jiang, Jianying; Shu, Lin; Zhang, Yahui

    2016-01-01

    AlN thin films were deposited on flexible Hastelloy tapes and Si (100) substrate by middle-frequency magnetron sputtering. A layer of Y2O3 films was used as a buffer layer for the Hastelloy tapes. A two-step deposition technique was used to prepare the AlN films. The effects of deposition parameters such as sputtering power, N2/Ar flow rate and sputtering pressure on the microstructure of the AlN thin films were systematically investigated. The results show that the dependency of the full width at half maximum (FWHM) of AlN/Y2O3/Hastelloy on the sputtering parameters is similar to that of AlN/Si (100). The FWHM of the AlN (002) peak of the prepared AlN films decreases with increasing sputtering power. The FWHM decreases with the increase of the N2/Ar flow rate or sputtering pressure, and increases with the further increase of the N2/Ar flow rate or sputtering pressure. The FWHM of the AlN/Y2O3/Hastelloy prepared under optimized parameters is only 3.7° and its root mean square (RMS) roughness is 5.46 nm. Based on the experimental results, the growth mechanism of AlN thin films prepared by the two-step deposition process was explored. This work would assist us in understanding the AlN film’s growth mechanism of the two-step deposition process, preparing highly c-axis–oriented AlN films on flexible metal tapes and developing flexible surface acoustic wave (SAW) sensors from an application perspective. PMID:28773806

  6. Effects of Sputtering Parameters on AlN Film Growth on Flexible Hastelloy Tapes by Two-Step Deposition Technique.

    PubMed

    Peng, Bin; Gong, Dongdong; Zhang, Wanli; Jiang, Jianying; Shu, Lin; Zhang, Yahui

    2016-08-10

    AlN thin films were deposited on flexible Hastelloy tapes and Si (100) substrate by middle-frequency magnetron sputtering. A layer of Y₂O₃ films was used as a buffer layer for the Hastelloy tapes. A two-step deposition technique was used to prepare the AlN films. The effects of deposition parameters such as sputtering power, N₂/Ar flow rate and sputtering pressure on the microstructure of the AlN thin films were systematically investigated. The results show that the dependency of the full width at half maximum (FWHM) of AlN/Y₂O₃/Hastelloy on the sputtering parameters is similar to that of AlN/Si (100). The FWHM of the AlN (002) peak of the prepared AlN films decreases with increasing sputtering power. The FWHM decreases with the increase of the N₂/Ar flow rate or sputtering pressure, and increases with the further increase of the N₂/Ar flow rate or sputtering pressure. The FWHM of the AlN/Y₂O₃/Hastelloy prepared under optimized parameters is only 3.7° and its root mean square (RMS) roughness is 5.46 nm. Based on the experimental results, the growth mechanism of AlN thin films prepared by the two-step deposition process was explored. This work would assist us in understanding the AlN film's growth mechanism of the two-step deposition process, preparing highly c-axis-oriented AlN films on flexible metal tapes and developing flexible surface acoustic wave (SAW) sensors from an application perspective.

  7. Preparation of highly c-axis oriented AlN thin films on Hastelloy tapes with Y2O3 buffer layer for flexible SAW sensor applications

    NASA Astrophysics Data System (ADS)

    Peng, Bin; Jiang, Jianying; Chen, Guo; Shu, Lin; Feng, Jie; Zhang, Wanli; Liu, Xinzhao

    2016-02-01

    Highly c-axis oriented aluminum nitrade (AlN) films were successfully deposited on flexible Hastelloy tapes by middle-frequency magnetron sputtering. The microstructure and piezoelectric properties of the AlN films were investigated. The results show that the AlN films deposited directly on the bare Hastelloy substrate have rough surface with root mean square (RMS) roughness of 32.43nm and its full width at half maximum (FWHM) of the AlN (0002) peak is 12.5∘. However, the AlN films deposited on the Hastelloy substrate with Y2O3 buffer layer show smooth surface with RMS roughness of 5.46nm and its FWHM of the AlN (0002) peak is only 3.7∘. The piezoelectric coefficient d33 of the AlN films deposited on the Y2O3/Hastelloy substrate is larger than three times that of the AlN films deposited on the bare Hastelloy substrate. The prepared highly c-axis oriented AlN films can be used to develop high-temperature flexible SAW sensors.

  8. Machinability of hastelloy C-276 using Hot-pressed sintered Ti(C7N3)-based cermet cutting tools

    NASA Astrophysics Data System (ADS)

    Xu, Kaitao; Zou, Bin; Huang, Chuanzhen; Yao, Yang; Zhou, Huijun; Liu, Zhanqiang

    2015-05-01

    C-276 nickel-based alloy is a difficult-to-cut material. In high-speed machining of Hastelloy C-276, notching is a prominent failure mode due to high mechanical properties of work piece, which results in the short tool life and low productivity. In this paper, a newly developed Ti(C7N3)-based cermet insert manufactured by a hot-pressing method is used to machine the C-276 nickel-based alloy, and its cutting performances are studied. Based on orthogonal experiment method, the influence of cutting parameters on tool life, material removal rates and surface roughness are investigated. Experimental research results indicate that the optimal cutting condition is a cutting speed of 50 m/min, depth of cut of 0.4 mm and feed rate of 0.15 mm/r if the tool life and material removal rates are considered comprehensively. In this case, the tool life is 32 min and material removal rates are 3000 mm3/min, which is appropriate to the rough machining. If the tool life and surface roughness are considered, the better cutting condition is a cutting speed of 75 m/min, depth of cut of 0.6 mm and feed rate of 0.1 mm/r. In this case, the surface roughness is 0.59μm. Notch wear, flank wear, chipping at the tool nose, built-up edge(BUE) and micro-cracks are found when Ti(C7N3)-based cermet insert turned Hastelloy C-276. Oxidation, adhesive, abrasive and diffusion are the wear mechanisms, which can be investigated by the observations of scanning electron microscope and energy-dispersive spectroscopy. This research will help to guide studies on the evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy C-276 machining.

  9. Computational Thermodynamic Modeling of Hot Corrosion of Alloys Haynes 242 and HastelloyTM N for Molten Salt Service in Advanced High Temperature Reactors

    SciTech Connect

    V. Glazoff, Michael; Charit, Indrajt; Sabharwall, Piyush

    2014-09-17

    An evaluation of thermodynamic aspects of hot corrosion of the superalloys Haynes 242 and HastelloyTM N in the eutectic mixtures of KF and ZrF4 is carried out for development of Advanced High Temperature Reactor (AHTR). This work models the behavior of several superalloys, potential candidates for the AHTR, using computational thermodynamics tool (ThermoCalc), leading to the development of thermodynamic description of the molten salt eutectic mixtures, and on that basis, mechanistic prediction of hot corrosion. The results from these studies indicated that the principal mechanism of hot corrosion was associated with chromium leaching for all of the superalloys described above. However, HastelloyTM N displayed the best hot corrosion performance. This was not surprising given it was developed originally to withstand the harsh conditions of molten salt environment. However, the results obtained in this study provided confidence in the employed methods of computational thermodynamics and could be further used for future alloy design efforts. Finally, several potential solutions to mitigate hot corrosion were proposed for further exploration, including coating development and controlled scaling of intermediate compounds in the KF-ZrF4 system.

  10. Crack propagation in Hastelloy X

    SciTech Connect

    Weerasooriya, T.; Strizak, J.P.

    1980-05-01

    The fatigue and creep crack growth rates of Hastelloy X were examined both in air and impure helium. Creep crack growth rate is higher in air and impure helium at 650/sup 0/C. Initial creep crack growth from the original sharp fatigue crack is by an intergranular mode of fracture. As the cracking accelerates at higher stress intensities, growth is by a mixed mode of both intergranular and transgranular fracture. Fatigue crack growth rate increases with increasing temperature and decreasing frequency for the range of stress intensities reported in the literature and is lower in impure helium than in air.

  11. Relation of Engine Turbine-blade Life to Stress-rupture Properties of the Alloys, Stellite 21, Hastelloy B, Cast S-816, Forged S-816, X-40, Nimonic 80, Refractaloy 26, N-155, and Inconel X

    NASA Technical Reports Server (NTRS)

    Garrett, F B; Yaker, C

    1951-01-01

    An investigation was conducted to relate the engine performance of the heat-resistant alloys, Stellite 21, Hastelloy B, cast S-816, forged S-816, X-40, Nimonic 80, Refractory 26, N-155, and Iconel X to their stress-rupture properties. The engine test consisted of the repetition of a 20-minute cycle, 15 minutes at rated speed and approximately 5 minutes at idle. The results of the investigation indicated a direct correlation between stress-rupture life and blade life for the relatively low-strength alloys. The stress-rupture life and blade life for the relatively high-strength alloys did not correlate because of the effects of the vibratory stresses and the corrosive-gas atmosphere.

  12. Effects of room-temperature tensile fatigue on critical current and n-value of IBAD-MOCVD YBa2Cu3O7-x /Hastelloy coated conductor

    NASA Astrophysics Data System (ADS)

    Rogers, Samuel; Kan Chan, Wan; Schwartz, Justin

    2016-08-01

    REBa2Cu3O7-x (REBCO) coated conductors potentially enable a multitude of superconducting applications, over a wide range of operating temperatures and magnetic fields, including high-field magnets, energy storage devices, motors, generators, and power transmission systems (Zhang et al 2013 IEEE Trans. Appl. Supercond. 23 5700704). Many of these are AC applications and thus the fatigue properties may be limiting (Vincent et al 2013 IEEE Trans. Appl. Supercond. 23 5700805). Previous electromechanical studies have determined the performance of REBCO conductors under single cycle loads (Barth et al 2015 Supercond. Sci. Technol. 28 045011), but an understanding of the fatigue properties is lacking. Here the fatigue behavior of commercial ion beam assisted deposition-metal organic chemical vapor deposition REBCO conductors on Hastelloy substrates is reported for axial tensile strains up to 0.5% and up to 100 000 cycles. Failure mechanisms are investigated via microstructural studies. Results show that REBCO conductors retained I c(ɛ)/I c0 = 0.9 for 10 000 cycles at ɛ = 0.35% and ɛ = 0.45% strain, and ɛ = 0.5% for 100 cycles. The main cause of fatigue degradation in REBCO conductors is crack propagation that initiates at the slitting defects that result from the manufacturing process.

  13. Ferroelectric and ferromagnetic properties of epitaxial BiFeO{sub 3}-BiMnO{sub 3} films on ion-beam-assisted deposited TiN buffered flexible Hastelloy

    SciTech Connect

    Xiong, J.; Matias, V.; Jia, Q. X.; Tao, B. W.; Li, Y. R.

    2014-05-07

    Growth of multifunctional thin films on flexible substrates is of great technological significance since such a platform is needed for flexible electronics. In this study, we report the growth of biaxially aligned (BiFeO{sub 3}){sub 0.5}:(BiMnO{sub 3}){sub 0.5} [BFO-BMO] films on polycrystalline Hastelloy by using a biaxially aligned TiN as a seed layer deposited by ion-beam-assisted deposited and a La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) as a buffer layer deposited by pulsed laser deposition. The LSMO is used not only as a buffer layer but also as the bottom electrode of the BFO-BMO films. X-ray diffraction showed that the BFO-BMO films are biaxially oriented along both in-plane and out-of-plane directions. The BFO-BMO films on flexible metal substrates showed a polarization of 22.9 μC/cm{sup 2}. The magnetization of the BFO-BMO/LSMO is 62 emu/cc at room temperature.

  14. Air oxidation and seawater corrosion of Hastelloy S and Hastelloy C-4

    SciTech Connect

    Fullam, H.T.

    1980-03-01

    A program is currently under way at the Pacific Northwest Laboratory (PNL) to develop the data and technology needed to permit the licensing of /sup 90/SrF/sub 2/ as a radioisotope heat source fuel for terrestrial applications. The WESF /sup 90/SrF/sub 2/ storage capsule consists of a Hastelloy C-276 inner capsule (2 in. I.D. x 19 in. long) and a 316L stainless steel outer capsule (2-3/8 in. I.D. x 20 in. long). Preliminary experimental tests and theoretical calculations show that the WESF storage capsule is incapable of meeting current licensing requirements for heat sources that are to be used for terrestrial applications. Therefore, the DOE decision was to develop a new heat source design that would retain the existing WESF Hastelloy C-276 inner capsule and replace the current WESF outer capsule with a new outer capsule capable of meeting current licensing requirements. Based on a number of factors, Hastelloy S was selected as the outer capsule material. Hastelloy C-4 was selected as a backup material in case the Hastelloy S had to be rejected for any reason. This report summarizes the results of studies carried out to determine the effects of both air oxidation at heat source operating temperatures and seawater corrosion on the tensile properties of the outer capsule materials.

  15. Weldability evaluations and weldment properties of Hastelloy X

    SciTech Connect

    King, J.F.; McCoy, H.E.; Rittenhouse, P.L.

    1981-01-01

    Studies of weldability and weldment properties were conducted on commerical heats of Hastelloy X. Weldment preparation was done using several combinations of welding techniques and filler metals. Evaluation methods employed included hot cracking susceptibility and tensile and creep properties measured both before and after aging at 593 to 871/sup 0/C for up to 10,000 h.

  16. Effects of oxidation on the impact energy of Hastelloy S and Hastelloy C-4 Charpy V-notch specimens heated in air at 600 to 800

    SciTech Connect

    Fullam, H.T.

    1981-01-01

    The /sup 90/SrF/sub 2/ heat source being developed at PNL utilizes a Hastelloy S or Hastelloy C-4 outer capsule having a 0.5-in.-thick wall to contain the Hastelloy C-276 inner capsule. The primary objective of the study was to demonstrate that the air oxidation of the outer capsule that could occur during heat-source service would not degrade the ductility and Charpy impact strength of the capsule below the licensing requirements given in Section 1.1. The /sup 90/SrF/sub 2/ heat source under development is intended for general-purpose use. Compatibility considerations limit the interface temperature between the /sup 90/SrF/sub 2/ and Hastelloy C-276 inner capsule to a maximum of 800/sup 0/C. The outer capsule surface temperature will be somewhat less than 800/sup 0/C, and depending on the service, may be substantially lower. The oxidation tests were therefore carried out at 600/sup 0/ to 800/sup 0/C for exposures up to 10,000h to cover the range of temperature the outer capsule might expect to encounter in service. The results showed that the oxidation of Hastelloy S and Hastelloy C-4 in air at 600/sup 0/ to 800/sup 0/C is very slow, and both alloys form adherent oxide layers that serve to protect the underlying metal. Subsurface attack of Hastelloy S and Hastelloy C-4 due to oxidation was greater than expected, considering the slow oxidation rates of the two alloys at 600/sup 0/ to 800/sup 0/C. Estimates of subsurface attack, determined from micrographs of the oxidized specimens, showed erratic results and it was impossible to assign any type of rate equation to the subsurface attack. A conservative estimate of long-term effects can be made using a linear extrapolation of the test results. There were no significant differences between the room-temperature Charpy impact energy of Hastelloy S and Hastelloy C-4 specimens oxidized in air at 600/sup 0/ to 800/sup 0/C and control specimens heated in vacuum.

  17. Influence of temperature, environment, and thermal aging on the continuous cycle fatigue behavior of Hastelloy X and Inconel 617

    SciTech Connect

    Strizak, J.P.; Brinkman, C.R.; Booker, M.K.; Rittenhouse, P.L.

    1982-04-01

    Results are presented for strain-controlled fatigue and tensile tests for two nickel-base, solution-hardened reference structural alloys for use in several High-Temperature Gas-Cooled Reactor (HTGR) concepts. These alloys, Hastelloy X and Inconel 617, were tested from room temperature to 871/sup 0/C in air and impure helium. Materials were tested in both the solution-annealed and the preaged conditios, in which aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are given between the strain-controlled fatigue lives of these and several other commonly used alloys, all tested at 538/sup 0/C. An analysis is also presented of the continuous cycle fatigue data obtained from room temperature to 427/sup 0/C for Hastelloy G, Hastelloy X, Hastelloy C-276, and Hastelloy C-4, an effort undertaken in support of ASME code development.

  18. Effects of high temperature brazing and thermal cycling on mechanical properties of Hastelloy X.

    NASA Technical Reports Server (NTRS)

    Dicus, D. L.; Buckley, J. D.

    1973-01-01

    Data are presented on the effects of brazing alloy, brazing operation, thermal cycling, and combinations of these on the yield strength, elongation, ultimate tensile strength, and fatigue life of thin gage Hastelloy X. These data show that brazing with a Ni-Pd-Au alloy at 1461 K resulted in reductions of 35 percent in yield strength and elongation, 6 percent in ultimate tensile strength, and 18 percent in fatigue limit of Hastelloy X, as compared with as-received material. Subsequent exposure to 200 thermal cycles between 533 K and 1144 K after brazing caused further losses of 4 percent in yield strength, 8 percent in ultimate tensile strength, and 6 percent in fatigue limit.

  19. Creep and tensile properties of alloy 800H-Hastelloy X weldments. [HTGR

    SciTech Connect

    McCoy, H. E.; King, J. F.

    1983-08-01

    Hastelloy X and alloy 800H were joined satisfactorily by the gas tungsten arc welding process with ERNiCr-3 filler and the shielded metal arc welding process with Inco Weld A filler. Test specimens were of two types: (1) made entirely of deposited Inco Weld A and (2) machined transverse across the weldments to include Hastelloy X, filler metal (ERNiCr-3 or Inco Weld A), and alloy 800H. They were aged 2000 and 10,000 h and subjected to short-term tensile and creep tests. Inco Weld A and ERNiCr-3 are both suitable filler metals and result in welds that are stronger than the alloy 800H base metal.

  20. Creep-rupture tests of internally pressurized Hastelloy-X tubes

    NASA Technical Reports Server (NTRS)

    Gumto, K. H.; Colantino, G. J.

    1973-01-01

    Seamless Hastelloy-X tubes with 0.375-in. outside diameter and 0.025-in. wall thickness were tested to failure at temperatures from 1400 to 1650 F and internal helium pressures from 800 to 1800 psi. Lifetimes ranged from 58 to 3600 hr. The creep-rupture strength of the tubes was from 20 to 40 percent lower than that of sheet specimens. Larson-Miller correlations and photomicrographs of some specimens are presented.

  1. Permeation of hydrogen in hastelloy C-276 alloy at high temperature

    SciTech Connect

    Zhang, D.; Liu, W.; Qian, Y.; Que, J.

    2015-03-15

    Tritium is generated by the interaction of neutrons with the lithium and beryllium in the molten salt reactors (MSRs), which use FLiBe as one of solvents of fluoride fuel. Tritium as by-product in the MSRs is an important safety issue because it could easily diffuse into environment through high temperature heat exchangers. The experimental technique of gas driven permeation has been used to investigate the transport parameter of hydrogen in Hastelloy C-276 which is considered as one of the candidate for structure materials. The measurements were carried out at the temperature range of 400-800 Celsius degrees with hydrogen loading pressures ranging from 5*10{sup 3} to 4*10{sup 4} Pa. The H diffusive transport parameters for Hastelloy C-276 follow an Arrhenius law in this temperature range. Regarding diffusivity and Sieverts' constant, Hastelloy C-276 has lower values compared with Ni201 alloy. The possible reason may be the trapping effects, which were formed by the alloying elements of Mo and Cr in the matrix. At the same time, the thin oxidation layer formed by the high Cr content could lead to a slower dissociation process of H{sub 2} at the surface. (authors)

  2. Weldability and weld performance of a special grade Hastelloy-X modified for high-temperature gas-cooled reactors

    SciTech Connect

    Shimizu, S.; Mutoh, Y.

    1984-07-01

    The characteristics of weld defects in the electron beam (EB) welding and the tungsten inert gas (TIG) arc welding for Hastelloy-XR, a modified version of Hastelloy-X, are clarified through the bead-on-plate test and the Trans-Varestraint test. Based on the results, weldabilities on EB and TIG weldings for Hastelloy-XR are discussed and found to be almost the same as Hastelloy-X. The creep rupture behaviors of the welded joints are evaluated by employing data on creep properties of the base and the weld metals. According to the evaluation, the creep rupture strength of the EB-welded joint may be superior to that of the TIG-welded joint. The corrosion test in helium containing certain impurities is conducted for the weld metals. There is no significant difference of such corrosion characteristics as weight gain, internal oxidation, depleted zone, and so on between the base and the weld metals. Those are superior to Hastelloy-X.

  3. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  4. 2G HTS wires made on 30 μm thick Hastelloy substrate

    NASA Astrophysics Data System (ADS)

    Sundaram, A.; Zhang, Y.; Knoll, A. R.; Abraimov, D.; Brownsey, P.; Kasahara, M.; Carota, G. M.; Nakasaki, R.; Cameron, J. B.; Schwab, G.; Hope, L. V.; Schmidt, R. M.; Kuraseko, H.; Fukushima, T.; Hazelton, D. W.

    2016-10-01

    REBCO (RE = rare earth) based high temperature superconducting (HTS) wires are now being utilized for the development of electric and electromagnetic devices for various industrial, scientific and medical applications. In the last several years, the increasing efforts in using the so-called second generation (2G) HTS wires for some of the applications require a further increase in their engineering current density (J e). The applications are those typically related to high magnetic fields where the higher J e of a REBCO wire, in addition to its higher irreversibility fields and higher mechanical strength, is already a major advantage over other superconducting wires. An effective way to increase the J e is to decrease the total thickness of a wire, for which using a thinner substrate becomes an obvious and attractive approach. By using our IBAD-MOCVD (ion beam assisted deposition-metal organic chemical vapor deposition) technology we have successfully made 2G HTS wires using a Hastelloy® C276 substrate that is only 30 μm in thickness. By using this thinner substrate instead of the typical 50 μm thick substrate and with a same critical current (I c), the J e of a wire can be increased by 30% to 45% depending on the copper stabilizer thickness. In this paper, we report the fabrication and characterization of the 2G HTS wires made on the 30 μm thick Hastelloy® C276 substrate. It was shown that with the optimization in the processing protocol, the surface of the thinner Hastelloy® C276 substrate can be readily electropolished to the quality needed for the deposition of the buffer stack. Same in the architecture as that on the standard 50 μm thick substrate, the buffer stack made on the 30 μm thick substrate showed an in-plane texture with a Δϕ of around 6.7° in the LaMnO3 cap layer. Low-temperature in-field transport measurement results suggest that the wires on the thinner substrate had achieved equivalent superconducting performance, most importantly the I

  5. Thermomechanical deformation behavior of a dynamic strain aging alloy, Hastelloy X

    NASA Technical Reports Server (NTRS)

    Castelli, Michael G.; Miner, Robert V.; Robinson, David N.

    1992-01-01

    An experimental study was performed to identify the effects of dynamic strain aging (solute drag) and metallurgical instabilities under thermomechanical loading conditions. The study involved a series of closely controlled thermomechanical deformation tests on the solid-solution-strenghened nickel-base superalloy, Hastelloy X. This alloy exhibits a strong isothermal strain aging peak at approximately 600 C, promoted by the effects of solute drag and precipitation hardening. Macroscopic thermomechanical hardening trends are correlated with microstructural characteristics through the use of transmission electron microscopy. These observations are compared and contrasted with isothermal conditions. Thermomechanical behavior unique to the isothermal database is identified and discussed. The microstructural characteristics were shown to be dominated by effects associated with the highest temperature of the thermomechanical cycle. Results indicate that the deformation behavior of Hastelloy X is thermomechanically path dependent. In addition, guidance is given pertaining to deformation modeling in the context of macroscopic unified theory. An internal state variable is formulated to qualitatively reflect the isotropic hardening trends identified in the TMD experiments.

  6. Thermomechanical cyclic hardening behavior of Hastelloy-X. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Bartolotta, P. A.

    1985-01-01

    Experimental evidence of thermomechanical history dependence on the cyclic hardening behavior of a representative combustor liner material Hastelloy-X is presented, along with a discussion about the relevant concept of thermomechanical path dependence. Based on the experimental results, a discussion is given on the inadequacy of formulating nonisothermal constitutive equations solely on the basis of isothermal testing. Finally, the essence of a mathematical representation of thermoviscoplasticity is presented that qualitatively accounts for the observed hereditary behavior. This is achieved by formulating the scaler evolutionary equation in an established viscoplastic theory to reflect thermomechanical path dependence. Although the necessary nonisothermal tests for further quantifying the thermoviscoplastic model have been identified, such data are not yet available.

  7. Total hemispherical emissivity of very high temperature reactor (VHTR) candidate materials: Hastelloy X, Haynes 230, and Alloy 617

    NASA Astrophysics Data System (ADS)

    Maynard, Raymond K.

    An experimental system was constructed in accordance with the standard ASTM C835-06 to measure the total hemispherical emissivity of structural materials of interest in Very High Temperature Reactor (VHTR) systems. The system was tested with304 stainless steel as well as for oxidized and un-oxidized nickel, and good reproducibility and agreement with the literature data was found. Emissivity of Hastelloy X was measured under different conditions that included: (i) "as received" (original sample) from the supplier; (ii) with increased surface roughness; (iii) oxidized, and; (iv) graphite coated. Measurements were made over a wide range of temperatures. Hastelloy X, as received from the supplier, was cleaned before additional roughening of the surface and coating with graphite. The emissivity of the original samples (cleaned after received) varied from around 0.18 to 0.28 in the temperature range of 473 K to 1498 K. The apparent emissivity increased only slightly as the roughness of the surface increased (without corrections for the increased surface area due to the increased surface roughness). When Hastelloy X was coated with graphite or oxidized however, its emissivity was observed to increase substantially. With a deposited graphite layer on the Hastelloy, emissivity increased from 0.2 to 0.53 at 473 K and from 0.25 to 0.6 at 1473 K; a finding that has strong favorable safety implications in terms of decay heat removal in post-accident VHTR environments. Although initial oxidation of Hastelloy X increased the emissivity prolonged oxidation did not significantly increase emissivity. However as there is some oxidation of Hastelloy X used in the construction of VHTRs, this represents an essentially neutral finding in terms of the safety implications in post-accident VHTR environments. The total hemispherical emissivity of Haynes 230 alloy, which is regarded as a leading candidate material for heat exchangers in VHTR systems, was measured under various surface

  8. The effects of high-temperature brazing and thermal cycling on the mechanical properties of Hastelloy X

    NASA Technical Reports Server (NTRS)

    Dicus, D. L.; Buckley, J. D.

    1972-01-01

    Data are presented on the effects of brazing alloy, brazing operation, thermal cycling, and combinations of these on the yield strength, elongation, tensile strength, and fatigue life of thin gage Hastelloy X. These data show that brazing at 1461 K (2170 F) with a Ni-Pd-Au alloy and subsequent exposure to 200 service thermal cycles between 533 and 1144 K (500 and 1600 F) result in reduction of as much as 39 percent in yield strength, 33 percent in elongation, 14 percent in tensile strength, and 26 percent in fatigue limit of Hastelloy X, as compared to as-received materials. These property losses are primarily caused by the brazing operation rather than the subsequent service thermal cycles.

  9. Laser texturing of Hastelloy C276 alloy surface for improved hydrophobicity and friction coefficient

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.

    2016-03-01

    Laser treatment of Hastelloy C276 alloy is carried out under the high pressure nitrogen assisting gas environment. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools including, scanning electron and atomic force microscopes, X-ray diffraction, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. Microhardness is measured and the residual stress formed in the laser treated surface is determined from the X-ray data. The hydrophibicity of the laser treated surface is assessed using the sessile drop method. Friction coefficient of the laser treated layer is obtained incorporating the micro-tribometer. It is found that closely spaced laser canning tracks create a self-annealing effect in the laser treated layer and lowers the thermal stress levels through modifying the cooling rates at the surface. A dense structure, consisting of fine size grains, enhances the microhardness of the surface. The residual stress formed at the surface is compressive and it is in the order of -800 MPa. Laser treatment improves the surface hydrophobicity significantly because of the formation of surface texture composing of micro/nano-pillars.

  10. Material Data Representation of Hysteresis Loops for Hastelloy X Using Artificial Neural Networks

    NASA Technical Reports Server (NTRS)

    Alam, Javed; Berke, Laszlo; Murthy, Pappu L. N.

    1993-01-01

    The artificial neural network (ANN) model proposed by Rumelhart, Hinton, and Williams is applied to develop a functional approximation of material data in the form of hysteresis loops from a nickel-base superalloy, Hastelloy X. Several different ANN configurations are used to model hysteresis loops at different cycles for this alloy. The ANN models were successful in reproducing the hysteresis loops used for its training. However, because of sharp bends at the two ends of hysteresis loops, a drift occurs at the corners of the loops where loading changes to unloading and vice versa (the sharp bends occurred when the stress-strain curves were reproduced by adding stress increments to the preceding values of the stresses). Therefore, it is possible only to reproduce half of the loading path. The generalization capability of the network was tested by using additional data for two other hysteresis loops at different cycles. The results were in good agreement. Also, the use of ANN led to a data compression ratio of approximately 22:1.

  11. Effect of Heat Treatment on Liquation Cracking in Continuous Fiber and Pulsed Nd:YAG Laser Welding of HASTELLOY X Alloy

    NASA Astrophysics Data System (ADS)

    Pakniat, M.; Ghaini, F. Malek; Torkamany, M. J.

    2017-09-01

    Laser welding of HASTELLOY X is highly feasible; however, hot cracking can be a matter of concern. The objective of this study is to assess the effect of solution heat treatment on susceptibility to liquation cracking in welding of a 2-mm-thick HASTELLOY X plate. In addition, Nd-YAG pulsed laser (400 W) and continuous wave (CW) fiber laser (600 W) were compared with each other in this respect. Results revealed that performing the prewelding solution heat treatment reduces the tendency for occurrence of liquation cracking. Furthermore, it was established that by increasing pulse frequency, there was a significant reduction in the tendency for liquation cracking. With CW laser welding of HASTELLOY X in the solution-heat-treated condition, the tendency for heat-affected zone (HAZ) cracking was found to be minimized.

  12. Compatibility of aluminide-coated Hastelloy x and Inconel 617 in a simulated gas-cooled reactor environment

    SciTech Connect

    Chin, J.; Johnson, W. R.; Chen, K.

    1982-03-01

    Commercially prepared aluminide coatings on Hastelloy X and Inconel 617 substrates were exposed to controlled-impurity helium at 850/sup 0/ and 950/sup 0/C for 3000 h. Optical and scanning electron (SEM) microscopy, electron microprobe profiles, and SEM X-ray mapping were used to evaluate and compare exposed and unexposed control samples. Four coatings were evaluated: aluminide, aluminide with platinum, aluminide with chromium, and aluminide with rhodium. With extended time at elevated temperature, nickel diffused into the aluminide coatings to form epsilon-phase (Ni/sub 3/Al). This diffusion was the primary cause of porosity formation at the aluminide/alloy interface.

  13. The oxidation resistance optimization of titanium carbide/hastelloy (Ni-based alloy) composites applied for intermediate-temperature solid oxide fuel cell interconnects

    NASA Astrophysics Data System (ADS)

    Qi, Qian; Liu, Yan; Wang, Lujie; Huang, Jian; Xin, Xianshuang; Gai, Linlin; Huang, Zhengren

    2017-08-01

    Titanium carbide/hastelloy (TiC/hastelloy) composites are potential candidates for intermediate-temperature solid oxide fuel cell interconnects. In this work, TiC/hastelloy composites with suitable coefficient of thermal expansion are fabricated by in-situ reactive infiltration method, and their properties are optimized by adjusting TiC particle size (dTiC). The oxidation process of TiC/hastelloy composites is comprehensive performance of TiC and Ni-Cr alloy and determined by outward diffusion of Ti and Ni atoms and internal diffusion of O2. The oxidation resistance of composites could be improved by the decrease of dTiC through accelerating the formation of continuous and dense TiO2/Cr2O3 oxide scale. Moreover, the electrical conductivity of composites at 800 °C for 100 h is 5600-7500 S cm-1 and changes little with the prolongation of oxidation time. The decrease of dTiC is favorable for the properties optimization, and composites with 2.16 μm TiC exhibits good integrated properties.

  14. Collect Available Creep-Fatigue Data and Study Existing Creep-Fatigue Evaluation Procedures for Grade 91 and Hastelloy XR

    SciTech Connect

    Tai Asayama; Yukio Tachibana

    2007-09-30

    This report describes the results of investigation on Task 5 of DOE/ASME Materials Project based on a contract between ASME Standards Technology, LLC (ASME ST-LLC) and Japan Atomic Energy Agency (JAEA). Task 5 is to collect available creep-fatigue data and study existing creep-fatigue evaluation procedures for Grade 91 steel and Hastelloy XR. Part I of this report is devoted to Grade 91 steel. Existing creep-fatigue data were collected (Appendix A) and analyzed from the viewpoints of establishing a creep-fatigue procedure for VHTR design. A fair amount of creep-fatigue data has been obtained and creep-fatigue phenomena have been clarified to develop design standards mainly for fast breeder reactors. Following this, existing creep-fatigue procedures were studied and it was clarified that the creep-fatigue evaluation procedure of the ASME-NH has a lot of conservatisms and they were analyzed in detail from the viewpoints of the evaluation of creep damage of material. Based on the above studies, suggestions to improve the ASME-NH procedure along with necessary research and development items were presented. Part II of this report is devoted to Hastelloy XR. Existing creep-fatigue data used for development of the high temperature structural design guideline for High Temperature Gas-cooled Reactor (HTGR) were collected. Creep-fatigue evaluation procedure in the design guideline and its application to design of the intermediate heat exchanger (IHX) for High Temperature Engineering Test Reactor (HTTR) was described. Finally, some necessary research and development items in relation to creep-fatigue evaluation for Gen IV and VHTR reactors were presented.

  15. Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Jaske, C. E.; Rice, R. C.; Buchheit, R. D.; Roach, D. B.; Porfilio, T. L.

    1976-01-01

    An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study.

  16. Effect of mechanical polishing on corrosion behavior of Hastelloy C22 coating prepared by high power diode laser cladding

    NASA Astrophysics Data System (ADS)

    Wang, Qin-Ying; Bai, Shu-Lin; Zhao, Yun-Hong; Liu, Zong-De

    2014-06-01

    Hastelloy C22 coatings were prepared on mild steel by high power diode laser cladding technique. In order to investigate the effect of mechanical polishing on corrosion behavior, the coatings with original surface (coating C1) and new surfaces after mechanical polishing away of 0.3 mm (coating C2) and 0.6 mm (coating C3) in depth were studied. Their microstructures and compositions were measured, and corrosion resistance in seawater was studied. The planar, cellular and dendritic solidifications were found from the coating/substrate interface to the top surface of coatings. In coating C1, smallest size primary solidification containing mainly Ni and largest quantity of eutectic networks composed of Cr, Mo and W are dominant, and harmful carbide M(Cr, W)2C is found. While Mo6Ni6C phase exists only in coatings C2 and C3. The open circuit potential and electrochemical impedance spectroscopy of coating C1 are higher within two days, and then lower later than the other two coatings. Coatings C2 and C3 display larger stable radius of capacitive loop and lower corrosion current density owing to higher contents of Cr and Mo, as well as no harmful carbide at surface, which reveals higher corrosion resistance and lower corrosion rate than coating C1. Consequently, properly mechanical polishing of original coating surface is beneficial for improving its corrosion resistance.

  17. Analyzing the effect of cutting parameters on surface roughness and tool wear when machining nickel based hastelloy - 276

    NASA Astrophysics Data System (ADS)

    Khidhir, Basim A.; Mohamed, Bashir

    2011-02-01

    Machining parameters has an important factor on tool wear and surface finish, for that the manufacturers need to obtain optimal operating parameters with a minimum set of experiments as well as minimizing the simulations in order to reduce machining set up costs. The cutting speed is one of the most important cutting parameter to evaluate, it clearly most influences on one hand, tool life, tool stability, and cutting process quality, and on the other hand controls production flow. Due to more demanding manufacturing systems, the requirements for reliable technological information have increased. For a reliable analysis in cutting, the cutting zone (tip insert-workpiece-chip system) as the mechanics of cutting in this area are very complicated, the chip is formed in the shear plane (entrance the shear zone) and is shape in the sliding plane. The temperature contributed in the primary shear, chamfer and sticking, sliding zones are expressed as a function of unknown shear angle on the rake face and temperature modified flow stress in each zone. The experiments were carried out on a CNC lathe and surface finish and tool tip wear are measured in process. Machining experiments are conducted. Reasonable agreement is observed under turning with high depth of cut. Results of this research help to guide the design of new cutting tool materials and the studies on evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy - 276 machining.

  18. Reduction in mechanical anisotropy through high temperature heat treatment of Hastelloy X processed by Selective Laser Melting (SLM)

    NASA Astrophysics Data System (ADS)

    Etter, T.; Kunze, K.; Geiger, F.; Meidani, H.

    2015-04-01

    Selective Laser Melting (SLM) is an additive manufacturing technology used to directly produce metallic parts from thin powder layers. To evaluate the anisotropic mechanical properties, tensile test specimens of the Ni-base alloy Hastelloy X were built with the loading direction oriented either parallel (z-specimens) or perpendicular to the build-up direction (xy- specimens). Specimens were investigated in the “as-built” condition and after high temperature heat treatment. Tensile tests at room temperature and at 850°C of “as-built” material have shown different mechanical properties for z- and xy-specimens. The anisotropy is reflected in the Young's modulus, with lower values measured parallel to the build-up direction. It is shown that the anisotropy is significantly reduced by a subsequent recrystallization heat treatment. The characterization of microstructural and textural anisotropy was done by Electron Back Scatter Diffraction (EBSD) analysis. Predictions of Young's modulus calculated from the measured textures compare well with the data from tensile tests.

  19. Chemistry of glass-ceramic to metal bonding for header applications. I. Effect of treatments on Inconel 718 and Hastelloy C-276 metallic surfaces

    SciTech Connect

    Kramer, D P; Craven, S M; Schneider, R E; Moddeman, W E; Brohard, D W

    1984-02-02

    Auger electron spectroscopy and depth Auger profiling were used to study the surfaces of Inconel 718 and Hastelloy C-276. The metal surfaces were processed in the same manner as is presently being used in the manufacturing of glass-ceramic headers. At each step in the process, samples were studied with Auger spectroscopy to determine their resultant elemental surface composition and film thickness. In addition, the effect of a final plasma cleaning operation on the metal surface was examined. The results show that the type and concentration of surface species and the thickness of the surface oxides are dependent on the processing technique.

  20. High-temperature low-cycle fatigue and tensile properties of Hastelloy X and alloy 617 in air and HTGR-helium

    SciTech Connect

    Strizak, J.P.; Brinkman, C.R.; Rittenhouse, P.L.

    1981-01-01

    Results of strain controlled fatigue and tensile tests are presented for two nickel base solution hardened alloys which are reference structural alloys for use in several high temperature gas cooled reactor concepts. These alloys, Hastelloy X Inconel 617, were tested at temperatures ranging from room temperature to 871/sup 0/C in air and impure helium. Materials were tested in the solution annealed as well as in the pre-aged condition where aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are also given between the strain controlled fatigue lives of these alloys and several other commonly used alloys all tested at 538/sup 0/C.

  1. Dielectric spectroscopy of Pb0.92La0.08Zr0.52Ti0.48O3 films on hastelloy substrates with and without LaNiO3 buffer layers

    NASA Astrophysics Data System (ADS)

    Narayanan, Manoj; Ma, Beihai; Balachandran, U. (Balu); Li, Wei

    2010-01-01

    Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) films were deposited by sol-gel synthesis on Hastelloy substrates with and without a LaNiO3 buffer. The dielectric properties were measured as a function of temperature and frequency to study the cause of dielectric degradation in PLZT films directly on hastelloy substrates. These measurements indicated an increased charge carrier activity in films without a buffer layer. We propose that a region of the film closer to the substrate surface is more oxygen deficient than the bulk and is responsible for the degradation in properties rather than the presence of a low parasitic secondary-phase interfacial layer such as NiOx.

  2. Spray pyrolysis of MgO templates on Hastelloy C276 and 310-austenitic stainless steel substrates for Y Ba2Cu3O7 (YBCO) deposition by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Khateeb, Shadi Al; Button, T. W.; Abell, J. S.

    2010-09-01

    MgO thin films were deposited on Hastelloy C276 (HC) and 310 austenitic stainless steel by the spray pyrolysis technique, using magnesium nitrate and magnesium acetate as precursors. Thermogravimetrical analysis of the decomposition of the precursors was used to provide a guideline temperature for the thin film deposition. It was suggested that an amorphous MgO thin film was deposited on both 310-stainless steel and Hastelloy C-276 when using low concentration of the magnesium nitrate precursor. Higher concentrations were needed to obtain (200) oriented MgO films on C276. However, 310-stainless steel was found to not be a suitable substrate for MgO thin film deposition due to surface instability. A (200) oriented MgO thin film was grown on Hastelloy C276 using a magnesium acetate precursor at a much lower concentration compared to the nitrate precursor. The characterization of the thin films was done using scanning electron microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, x-ray diffraction 2θ-scans, rocking curves (ω-scans), and pole figure measurements. MgO was found to have a very weak in-plane texture.

  3. Effect of Continuous and Pulsed Current Gas Tungsten Arc Welding on Dissimilar Weldments Between Hastelloy C-276/AISI 321 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sharma, Sumitra; Taiwade, Ravindra V.; Vashishtha, Himanshu

    2017-03-01

    In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and μ was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also.

  4. Effect of Continuous and Pulsed Current Gas Tungsten Arc Welding on Dissimilar Weldments Between Hastelloy C-276/AISI 321 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sharma, Sumitra; Taiwade, Ravindra V.; Vashishtha, Himanshu

    2017-02-01

    In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and μ was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also.

  5. One new route to optimize the oxidation resistance of TiC/hastelloy (Ni-based alloy) composites applied for intermediate temperature solid oxide fuel cell interconnect by increasing graphite particle size

    NASA Astrophysics Data System (ADS)

    Qi, Qian; Liu, Yan; Wang, Lujie; Zhang, Hui; Huang, Jian; Huang, Zhengren

    2017-09-01

    TiC/hastelloy composites with suitable thermal expansion and excellent electrical conductivity are promising candidates for IT-SOFC interconnect. In this paper, the TiC/hastelloy composites are fabricated by in-situ reactive infiltration, and the oxidation resistance of composites is optimized by increasing graphite particle size. Results show that the increase of graphite particles size from 1 μm to 40 μm reduces TiC particle size from 2.68 μm to 2.22 μm by affecting the formation process of TiC. Moreover, the decrease of TiC particles size accelerates the fast formation of dense and continuous TiO2/Cr2O3 oxide layer, which bring down the mass gain (800 °C/100 h) from 2.03 mg cm-2 to 1.18 mg cm-2. Meanwhile, the coefficient of thermal expansion decreases from 11.15 × 10-6 °C-1 to 10.80 × 10-6 °C-1, and electrical conductivity maintains about 5800 S cm-1 at 800 °C. Therefore, the decrease of graphite particle size is one simple and effective route to optimize the oxidation resistance of composites, and meantime keeps suitable thermal expansion and good electrical conductivity.

  6. Bending stability of GaN grown on a metallic flexible substrate by plasma-assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Rodríguez, A. G.; Chávez-Veloz, S. G.; Compeán-García, V. D.; López-Luna, E.; Vidal, M. A.

    2017-08-01

    GaN thin films were grown on flexible metallic substrates by molecular beam epitaxy. MgO buffer layers were deposited by spin coating on Ni-Mo-Cr (Hastelloy C-276) alloy tapes that were used as substrates. The structural characterization of the GaN/MgO/hastelloy samples was performed by x-ray diffraction and Raman spectroscopy. The obtained nanometric films have the stable hexagonal phase (α-GaN) with an average crystallite size of 18 nm. The long and short range order of GaN decrease when the structure is bent. The most significant variations in the structural properties occur between 100 and 250 bending cycles.

  7. Thermodynamic Assessment of Hot Corrosion Mechanisms of Superalloys Hastelloy N and Haynes 242 in Eutectic Mixture of Molten Salts KF and ZrF4

    SciTech Connect

    Michael V. Glazoff

    2012-02-01

    The KF - ZrF4 system was considered for the application as a heat exchange agent in molten salt nuclear reactors (MSRs) beginning with the work carried out at ORNL in early fifties. Based on a combination of excellent properties such as thermal conductivity, viscosity in the molten state, and other thermo-physical and rheological properties, it was selected as one of possible candidates for the nuclear reactor secondary heat exchanger loop.

  8. Atlas of Formability: Hastelloy C-22

    DTIC Science & Technology

    1992-09-30

    but the twin boundaries show the 8 presence of necklacing. 6 950(1742) 0.50 9 7 950(1742) 1.0 Elongated grains with -10 % of small 10 recrystallized...grains. Some necklacing at the twin boundaries and slip bands are present. 8 950(1742) 5.0 11 9 950(1742) 20.0 Elongated grains with -15 % of small...12 r.zcrystallized grains (-9 gm). Some necklacing around the elongated grains and twin boundaries . Slip bands are also present. 10 1000(1832) 0.001

  9. High-temperature corrosion of UNS N10003 in molten Li2BeF4 (FLiBe) salt

    DOE PAGES

    Zheng, Guiqiu; Kelleher, Brian; He, Lingfeng; ...

    2015-07-30

    Here, corrosion testing of Hastelloy N in molten fluoride salt was performed in purified molten 27LiF-BeF2 (66-34mol%) (FLiBe) salt at 700°C for 1000 hours, in pure nickel and graphite capsules. In the nickel capsule tests, the near-surface region of the alloy exhibited an about 200 nm porous structure, an approximately 3.5 μm chromium depleted region, and MoSi2 precipitates. In tests performed in graphite capsules, the alloy samples gained weight due to the formation of a variety of Cr3C2, Cr7C3, Mo2C and Cr23C6, carbide phases on the surface and in the subsurface regions of the alloy. A Cr depleted region wasmore » observed in the near-surface region where Mo thermally diffused toward either surface or grain boundary, which induced approximately 1.4 μm Ni3Fe alloy layer in this region. The carbide containing layer extended to about 7 μm underneath the Ni3Fe layer. The presence of graphite dramatically changes the mechanisms of corrosion attack in Hastelloy N in molten FLiBe salt. Evaluated by in terms of the depth of attack, graphite clearly accelerates corrosion, but the results appear to indicate that the formation of Cr23C6 phase might stabilize the Cr and mitigate its dissolution in molten FLiBe salt.« less

  10. Thermomechanical characterization of Hastelloy-X under uniaxial cyclic loading

    NASA Technical Reports Server (NTRS)

    Ellis, J. R.; Bartolotta, P. A.; Allen, G. P.; Robinson, D. N.

    1986-01-01

    In most high-temperature engineering applications, components are subjected to complex combinations of thermal and mechanical loading during service. A number of viscoplastic constitutive models were proposed which potentially can provide mathematical descriptions of material response under such conditions. Implementation of these models into large finite element codes such as MARC has already resulted in much improved inelastic analysis capability for hot-section aircraft engine components. However, a number of questions remain regarding the validity of methods adopted in characterizing these constitutive models for particular high-temperature materials. One area of concern is that the majority of experimental data available for this purpose are determined under isothermal conditions. This is in contrast to service conditions which, as noted above, almost always involve some form of thermal cycling. The obvious question arises as to whether a constitutive model characterized using an isothermal data base can adequately predict material response under thermomechanical conditions. An experimental program was initiated within the HOST program to address this particular concern. The results of the most recent isothermal and thermomechanical experiments are described.

  11. High-temperature corrosion of UNS N10003 in molten Li2BeF4 (FLiBe) salt

    SciTech Connect

    Zheng, Guiqiu; Kelleher, Brian; He, Lingfeng; Cao, Guoping; Anderson, Mark; Allen, Todd; Sridharan, Kumar

    2015-07-30

    Here, corrosion testing of Hastelloy N in molten fluoride salt was performed in purified molten 27LiF-BeF2 (66-34mol%) (FLiBe) salt at 700°C for 1000 hours, in pure nickel and graphite capsules. In the nickel capsule tests, the near-surface region of the alloy exhibited an about 200 nm porous structure, an approximately 3.5 μm chromium depleted region, and MoSi2 precipitates. In tests performed in graphite capsules, the alloy samples gained weight due to the formation of a variety of Cr3C2, Cr7C3, Mo2C and Cr23C6, carbide phases on the surface and in the subsurface regions of the alloy. A Cr depleted region was observed in the near-surface region where Mo thermally diffused toward either surface or grain boundary, which induced approximately 1.4 μm Ni3Fe alloy layer in this region. The carbide containing layer extended to about 7 μm underneath the Ni3Fe layer. The presence of graphite dramatically changes the mechanisms of corrosion attack in Hastelloy N in molten FLiBe salt. Evaluated by in terms of the depth of attack, graphite clearly accelerates corrosion, but the results appear to indicate that the formation of Cr23C6 phase might stabilize the Cr and mitigate its dissolution in molten FLiBe salt.

  12. Microscopic study of the structure of the Steel Ni-based Alloy: Hastelloy G35 Alloy

    NASA Astrophysics Data System (ADS)

    Sabir, F.; Ben Lenda, O.; Saissi, S.; Marbouh, K.; Tyouke, B.; Zerrouk, L.; Ibnlfassi, A.; Ouzaouit, K.; Elmadani, S.

    2017-03-01

    The study of the influence of heat treatment on changes of mechanical and structural properties of Steel Ni-based Alloy is a highly interdisciplinary topic at the interface of the physical chemistry of metallic materials, which also helps in environmental and economic protection.After heat treatment, the structural and micro-structural studies for the different transformation temperature led to identify phases formed and the morphology. This work has been carried out using different techniques: X-ray diffraction, optical microscopy and scanning electron microscopy.

  13. Evaluation of a sodium/Hastelloy-X heat pipe for wing leading edge cooling

    SciTech Connect

    Merrigan, M.A.; Sena, J.T.; Glass, D.E.

    1996-12-31

    This report covers assembly of a sodium heat pipe, testing to verify performance during start-up and under steady-state conditions with stagnation point heat loads to about 80 W/cm{sup 2}, performance analysis and evaluation. Evaluation of this leading edge cooling concept is offered and recommendations for further research discussed.

  14. Evaluation of Three Constitutive Models for the Prediction of Hastelloy X Elevated Temperature Cyclic Response

    NASA Technical Reports Server (NTRS)

    Moreno, V.

    1983-01-01

    The approach for the method development assumes that, for a thermally loaded structure, the overall strain history is defined by linear elastic analysis. The local stress history at a fatigue critical location is then determined from a one dimensional material behavior model and the local strain and temperature conditions. Three material models are currently being evaluated to assess their ability to predict relevant high temperature cyclic material response characteristics. They are: a time independent classical plasticity and creep representation, a time dependent viscoplastic model capable of predicting combined creep and plasticity effects, and an approximate elastic analysis approach that uses a series of stress-strain curves and a cyclic hardening model to determine reverse plasticity.

  15. Development of a Mathematical Model of Crevice Corrosion Propagation on Nickel Base Alloys in Natural and Chlorinated Sea Water

    DTIC Science & Technology

    1994-08-30

    then bromamines and chloramines are formed and the processes become even more complicated. [10]. 0 From the point of view of crevice corrosion ... Corrosion Propagation on Nickel Base Alloys in Natural and Chlorinated Sea Water Thi! os 7 -= n %:ý 7e~~r: :-ppcved tor piU&* : e --I . " dcktr!u-,J...Summary Crevice corrosion initiation and propagation of nickel base alloys Inconel 625, Hastelloy C276 and Hastelloy 22 in sea water and chlorinated sea

  16. Modeled as + n + n

    NASA Astrophysics Data System (ADS)

    Gibson, B. F.; Afnan, I. R.

    2014-08-01

    A three-body calculation for the and hypernuclei has been undertaken. The respective cores are . The interactions in the system, modeled as , are reasonably well known. For example, the p n interaction is well determined by the p n scattering data, the - p interaction can be fitted to the binding energy. The - n interaction can be fitted to α- n scattering data. For the 4He- n system the s-wave can be modeled alternatively as a repulsive potential or as an attractive potential with a forbidden bound state. We explore these alternatives in 6He, because the interaction comes into play in modeling as well as in our + n + n model of , where the valence neutrons are Pauli blocked from the s-shell of the core nucleus.

  17. N,N-Dimethylformamide

    Integrated Risk Information System (IRIS)

    N , N - Dimethylformamide ; CASRN 68 - 12 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarci

  18. N-N-Dimethylaniline

    Integrated Risk Information System (IRIS)

    N - N - Dimethylaniline ; CASRN 121 - 69 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcin

  19. Preliminary lifetime predictions for 304 stainless steel as the LANL ABC blanket material

    SciTech Connect

    Park, J.J.; Buksa, J.J.; Houts, M.G.; Arthur, E.D.

    1997-11-01

    The prediction of materials lifetime in the preconceptual Los Alamos National Laboratory (LANL) Accelerator-Based Conversion of Plutonium (ABC) is of utmost interest. Because Hastelloy N showed good corrosion resistance to the Oak Ridge National Laboratory Molten Salt Reactor Experiment fuel salt that is similar to the LANL ABC fuel salt, Hastelloy N was originally proposed for the LANL ABC blanket material. In this paper, the possibility of using 304 stainless steel as a replacement for the Hastelloy N is investigated in terms of corrosion issues and fluence-limit considerations. An attempt is made, based on the previous Fast Flux Test Facility design data, to predict the preliminary lifetime estimate of the 304 stainless steel used in the blanket region of the LANL ABC.

  20. N-Nitrosodi-N-propylamine

    Integrated Risk Information System (IRIS)

    N - Nitrosodi - N - propylamine ; CASRN 621 - 64 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for N

  1. 1/N

    SciTech Connect

    Coleman, S.

    1980-03-01

    There exist families of field theories with symmetry group SO(N) (or SU(N)) that become simpler as N becomes larger. More precisely, the solutions to these theories possess an expansion in powers of 1/N. This expansion is the subject of these lectures. The 1/N expansion can be used to analyze model field theories. The 1/N expansion is developed for phi/sup 4/ theory and applied to two two-dimensional models with similar combinatoric structures, the Gross-Neveu model and the CP/sup N-1/ model. These models display (in the leading 1/N approximation) such interesting phenomena as asymptotic freedom, dynamical symmetry breaking, dimensional transmutation, and non-perturbative confinement. It is possible that the 1/N expansion, with N the number of colors, might fruitfully be applied to quantum chromodynamics. Unfortunately, it is not possible to make a decisive test of the approximation, because no one knows how to compute even the first term in the expansion in closed form. However, it is possible to argue that this first term, whatever its detailed form, has many properties that are also shared by the real world, and which are otherwise underived from field theory. These include the saturation of scattering amplitudes by an infinite number of narrow resonances, the essential feature of dual-resonance models. (RWR)

  2. N-Nitroso-N-methylethylamine

    Integrated Risk Information System (IRIS)

    N - Nitroso - N - methylethylamine ; CASRN 10595 - 95 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments

  3. Large N

    NASA Astrophysics Data System (ADS)

    't Hooft, Gerard

    2002-09-01

    In the first part of this lecture, the 1/N expansion technique is illustrated for the case of the large-N sigma model. In large-N gauge theories, the 1/N expansion is tantamount to sorting the Feynman diagrams according to their degree of planarity, that is, the minimal genus of the plane onto which the diagram can be mapped without any crossings. This holds both for the usual perturbative expansion with respect to powers of ˜ {g}2 = g2N, as well as for the expansion of lattice theories in positive powers of 1/˜ {g}2. If there were no renormalization effects, the ˜ {g} expansion would have a finite radius of convergence. The zero-dimensional theory can be used for counting planar diagrams. It can be solved explicitly, so that the generating function for the number of diagrams with given 3-vertices and 4-vertices, can be derived exactly. This can be done for various kinds of Feynman diagrams. We end with some remarks about planar renormalization.

  4. .. P .,n

    NASA Website

    t~~ j~te~r~l aoc~~d b~f~r~ lift-off. ~~~~. zero for tni~ mi••ion ~~ 13~,16:~9;OOGmt. Te.i, r~,0rt has b~"n f~era.ea ~$oppl~ment11 to ... h ": r.. ...

  5. Study of metal corrosion using ac impedance techniques in the STS launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz M.

    1989-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 19 alloys under conditions similar to the STS launch environment. The alloys were: Zirconium 702, Hastelloy C-22, Inconel 625, Hastelloy C-276, Hastelloy C-4, Inconel 600, 7Mo + N, Ferralium 255, Inco Alloy G-3, 20Cb-3, SS 904L, Inconel 825, SS 304LN, SS 316L, SS 317L, ES 2205, SS 304L, Hastelloy B-2, and Monel 400. AC impedance data were gathered for each alloy after one hour immersion time in each of the following three electrolyte solutions: 3.55 percent NaCl, 3.55 percent NaCl-0.1N HCl, and 3.55 percent NaCl-1.0N HCl. The data were analyzed qualitatively using the Nyquist plot and quantitatively using the Bode plot. Polarization resistance, Rp, values were obtained using the Bode plot. Zirconium 702 was the most corrosion resistant alloy in the three electrolytes. The ordering of the other alloys according the their resistance to corrosion varied as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of Zirconium 702 and Ferralium 255 increased as the concentration of hydrochloric acid in the electrolyte increased. The corrosion resistance of the other 17 alloys decreased as the concentration of the hyrdochloric acid in the electrolyte increased.

  6. Phenomenology of n - n ¯ oscillations revisited

    DOE PAGES

    Gardner, S.; Jafari, E.

    2015-05-22

    We revisit the phenomenology of n-n¯ oscillations in the presence of external magnetic fields, highlighting the role of spin. We show, contrary to long-held belief, that the n-n¯ transition rate need not be suppressed, opening new opportunities for its empirical study.

  7. Resonances in the Λ n n system

    NASA Astrophysics Data System (ADS)

    Afnan, Iraj R.; Gibson, Benjamin F.

    2015-11-01

    Background: A bound state of the Λ n n system has been reported, but at least three theoretical papers question the existence of such a bound state. Purpose: We address the alternative question of whether there might exist a resonance in the Λ n n system, using a rank-one separable potential formulation of the Hamiltonian. Methods: We examine the eigenvalues of the kernel of the Faddeev equation in the complex energy plane using contour rotation to allow us to analytically continue the kernel onto the second energy sheet. The model Λ n interaction is fitted to the Λ p scattering length and effective range. Results: We follow the largest eigenvalue as the Λ n potentials are scaled and the Λ n n continuum is turned first into a resonance, and then into a bound state of the system. Conclusions: Because a change in the strength of the Λ n potential of as little as 5% will produce a Λ n n resonance, we infer that an experiment of the H3 (e,e'K+)3nΛ type at JLAB could be used to constrain the properties of the Λ n interaction.

  8. Synthesis of terephthalonitrile N,N-dioxide

    NASA Technical Reports Server (NTRS)

    Vanburen, K. E.

    1973-01-01

    The preparation is described of terephthalonitrile N,N prime-dioxide by the chlorination of terephthalaldehyde dioxime to yield terephthalohydroximol chloride, to which absolute methynol was added to yield the TPNO.

  9. Exact linear admittance of n+-n-n+ semiconductor structures

    NASA Astrophysics Data System (ADS)

    Eranen, S.; Sinkkonen, J.

    1985-10-01

    With the self-consistent solution of the linearized Boltzmann equation in the relaxation-time approximation for a spatially inhomogeneous electron system, the admittance of n+-n-n+ semiconductor structures is studied as a function of the length L of the moderately doped n region. It is shown that a one-dimensional treatment of the velocity space leads to the exact, analytical solution of the problem. In addition to the conventional admittance and the geometric capacitance of the n region, the equivalent circuit of the structure also includes the contact resistance and, as a new feature, the contact capacitance. For the strongly screened cases (L>>LD) the contact capacitance is approximately the permittivity ɛ of the n region divided by the Debye length LD and, further, becomes exactly equal to ɛL/6L2D in the weak-screening regime (LD>>L).

  10. Experimental verification of the Neuber relation at room and elevated temperatures. M.S. Thesis; [to predict stress-strain behavior in notched specimens of hastelloy x

    NASA Technical Reports Server (NTRS)

    Lucas, L. J.

    1982-01-01

    The accuracy of the Neuber equation at room temperature and 1,200 F as experimentally determined under cyclic load conditions with hold times. All strains were measured with an interferometric technique at both the local and remote regions of notched specimens. At room temperature, strains were obtained for the initial response at one load level and for cyclically stable conditions at four load levels. Stresses in notched members were simulated by subjecting smooth specimens to he same strains as were recorded on the notched specimen. Local stress-strain response was then predicted with excellent accuracy by subjecting a smooth specimen to limits established by the Neuber equation. Data at 1,200 F were obtained with the same experimental techniques but only in the cyclically stable conditions. The Neuber prediction at this temperature gave relatively accurate results in terms of predicting stress and strain points.

  11. Crystal structure of N,N,N',N',N'',N''-hexa-methyl-guanidinium cyanate 1.5-hydrate.

    PubMed

    Tiritiris, Ioannis; Kantlehner, Willi

    2015-12-01

    The title hydrated salt, C7H18N3 (+)·OCN(-).1.5H2O, was synthesized starting from N,N,N',N',N'',N''-hexa-methyl-guanidinium chloride by a twofold anion-exchange reaction. The asymmetric unit contains two cations, two cyanate anions and three water mol-ecules. One cation shows orientational disorder and two sets of N-atom positions were found related by a 60° rotation, with an occupancy ratio of 0.852 (6):0.148 (6). The C-N bond lengths in both guanidin-ium ions range from 1.329 (2) to 1.358 (10) Å, indicating double-bond character, pointing towards charge delocalization within the NCN planes. Strong O-H⋯N hydrogen bonds between the crystal water mol-ecules and the cyanate ions and strong O-H⋯O hydrogen bonds between the water mol-ecules are present, resulting in a two-dimensional hydrogen bonded network running parallel to the (001) plane. The hexa-methyl-guanidinium ions are packed in between the layers built up by water mol-ecules and cyanate ions.

  12. Finite N from resurgent large N

    NASA Astrophysics Data System (ADS)

    Couso-Santamaría, Ricardo; Schiappa, Ricardo; Vaz, Ricardo

    2015-05-01

    Due to instanton effects, gauge-theoretic large N expansions yield asymptotic series, in powers of 1 /N2. The present work shows how to generically make such expansions meaningful via their completion into resurgent transseries, encoding both perturbative and nonperturbative data. Large N resurgent transseries compute gauge-theoretic finite N results nonperturbatively (no matter how small N is). Explicit calculations are carried out within the gauge theory prototypical example of the quartic matrix model. Due to integrability in the matrix model, it is possible to analytically compute (fixed integer) finite N results. At the same time, the large N resurgent transseries for the free energy of this model was recently constructed. Together, it is shown how the resummation of the large N resurgent transseries matches the analytical finite N results up to remarkable numerical accuracy. Due to lack of Borel summability, Stokes phenomena has to be carefully taken into account, implying that instantons play a dominant role in describing the finite N physics. The final resurgence results can be analytically continued, defining gauge theory for any complex value of N.

  13. 4n pi electrons but stable: N,N-dihydrodiazapentacenes.

    PubMed

    Wu, Judy I; Wannere, Chaitanya S; Mo, Yirong; Schleyer, Paul von Ragué; Bunz, Uwe H F

    2009-06-05

    Despite having 4n pi electrons, dihydrodiazapentacenes are more viable than their 4n+2 pi azapentacene counterparts. Ab inito valence bond block-localized wave function (BLW) computations reveal that despite having 4n pi electrons, dihydrodiazapentacenes are stabilized and benefit substantially from four dihydropyrazine ethenamine (enamine) conjugations. Almost all of these dihydrodiazapentacenes have large negative overall nucleus independent chemical shifts NICS(0)(pizz) values even though their dihydropyrazine rings (e.g., for 6-H(2)) are modestly antiaromatic, as their paratropic contributions are attenuated by delocalization throughout the system.

  14. Improved InGaN/GaN light-emitting diodes with a p-GaN/n-GaN/p-GaN/n-GaN/p-GaN current-spreading layer.

    PubMed

    Zhang, Zi-Hui; Tan, Swee Tiam; Liu, Wei; Ju, Zhengang; Zheng, Ke; Kyaw, Zabu; Ji, Yun; Hasanov, Namig; Sun, Xiao Wei; Demir, Hilmi Volkan

    2013-02-25

    This work reports both experimental and theoretical studies on the InGaN/GaN light-emitting diodes (LEDs) with optical output power and external quantum efficiency (EQE) levels substantially enhanced by incorporating p-GaN/n-GaN/p-GaN/n-GaN/p-GaN (PNPNP-GaN) current spreading layers in p-GaN. Each thin n-GaN layer sandwiched in the PNPNP-GaN structure is completely depleted due to the built-in electric field in the PNPNP-GaN junctions, and the ionized donors in these n-GaN layers serve as the hole spreaders. As a result, the electrical performance of the proposed device is improved and the optical output power and EQE are enhanced.

  15. N-nitroso-N-methyldodecylamine and N-nitroso-N-methyltetradecylamine in hair-care products.

    PubMed

    Hecht, S S; Morrison, J B; Wenninger, J A

    1982-04-01

    N-Nitroso-N-methyldodecylamine and N-nitroso-N-methyltetradecylamine, which cause urinary bladder tumours in experimental animals, were detected in several hair-care products formulated with N,N-dimethyldodecylamine oxide. Quantitative determinations were made using a gas-liquid chromatograph interfaced with a thermal energy analyser and using [1-14C]N-nitroso-N-methyldodecylamine as an internal standard. The presence of the two nitrosamines was confirmed by high-pressure liquid chromatography with a thermal energy analyser as detector, by photolysis of samples and by combined gas chromatography-mass spectometry. To test the reproducibility of the method, a single shampoo was selected for replicate analysis and was found to contain 90 +/- 8 ppb N-nitroso-N-methyldodecylamine and 37 +/- 11 ppb N-nitroso-N-methyltetradecylamine. Levels of N-nitroso-N-methyldodecylamine in other hair-care products ranged from 11 to 873 ppb and those of n-nitroso-N-methyltetradecylamine from 8 to 254 ppb.

  16. Instantons and Large N

    NASA Astrophysics Data System (ADS)

    Mariño, Marcos

    2015-09-01

    Preface; Part I. Instantons: 1. Instantons in quantum mechanics; 2. Unstable vacua in quantum field theory; 3. Large order behavior and Borel summability; 4. Non-perturbative aspects of Yang-Mills theories; 5. Instantons and fermions; Part II. Large N: 6. Sigma models at large N; 7. The 1=N expansion in QCD; 8. Matrix models and matrix quantum mechanics at large N; 9. Large N QCD in two dimensions; 10. Instantons at large N; Appendix A. Harmonic analysis on S3; Appendix B. Heat kernel and zeta functions; Appendix C. Effective action for large N sigma models; References; Author index; Subject index.

  17. N-Nitroso-di-n-butylamine

    Integrated Risk Information System (IRIS)

    N - Nitroso - di - n - butylamine ; CASRN 924 - 16 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for

  18. Metal contacts to n-GaN

    NASA Astrophysics Data System (ADS)

    Dobos, L.; Pécz, B.; Tóth, L.; Horváth, Zs. J.; Horváth, Z. E.; Tóth, A.; Horváth, E.; Beaumont, B.; Bougrioua, Z.

    2006-11-01

    Al, Au, Ti/Al and Ti/Au contacts were prepared on n-GaN and annealed up to 900 °C. The structure, phase and morphology were studied by cross-sectional transmission and scanning electron microscopy as well as by X-ray diffraction (XRD), the electrical behaviour by current-voltage measurements. It was obtained that annealing resulted in interdiffusion, lateral diffusion along the surface, alloying and bowling up of the metal layers. The current-voltage characteristics of as-deposited Al and Ti/Al contacts were linear, while the Au and Ti/Au contacts exhibited rectifying behaviour. Except the Ti/Au contact which became linear, the contacts degraded during heat treatment at 900 °C. The surface of Au and Ti/Au contacts annealed at 900 °C have shown fractal-like structures revealed by scanning electron microscopy. Transmission electron microscopy and XRD investigations of the Ti/Au contact revealed that Au diffused into the n-GaN layer at 900 °C. X-ray diffraction examinations showed, that new Ti 2N, Au 2Ga and Ga 3Ti 2 interface phases formed in Ti/Au contact at 900 °C, new Ti 2N phase formed in Ti/Al contact at 700 and 900 °C, as well as new AlN interface phase developed in Ti/Al contact at 900 °C.

  19. First principles study of the ignition mechanism for hypergolic bipropellants: N,N,N',N'-tetramethylethylenediamine (TMEDA) and N,N,N',N'-tetramethylmethylenediamine (TMMDA) with nitric acid.

    PubMed

    Liu, Wei-Guang; Dasgupta, Siddharth; Zybin, Sergey V; Goddard, William A

    2011-05-26

    We report quantum mechanics calculations (B3LYP flavor of density functional theory) to determine the chemical reaction mechanism underlying the hypergolic reaction of pure HNO(3) with N,N,N',N'-tetramethylethylenediamine (TMEDA) and N,N,N',N'-tetramethylmethylenediamine (TMMDA). TMEDA and TMMDA are dimethyl amines linked by two CH(2) groups or one CH(2) group, respectively, but ignite very differently with HNO(3). We explain this dramatic difference in terms of the role that N lone-pair electrons play in activating adjacent chemical bonds. We identify two key atomistic level factors that affect the ignition delay: (1) The exothermicity for formation of the dinitrate salt from TMEDA or TMMDA. With only a single CH(2) group between basic amines, the diprotonation of TMMDA results in much stronger electrostatic repulsion, reducing the heat of dinitrate salt formation by 6.3 kcal/mol. (2) The reaction of NO(2) with TMEDA or TMMDA, which is the step that releases the heat and reactive species required to propagate the reaction. Two factors of TMEDA promote the kinetics by providing routes with low barriers to oxidize the C: (a) formation of a stable intermediate with a C-C double bond and (b) the lower bond energy for breaking the C-C single bond (by 18 kcal/mol comparing to alkane) between two amines. Both factors would decrease the ignition delay for TMEDA versus TMMDA. The same factors also explain the shorter ignition delay of 1,4-dimethylpiperazine (DMPipZ) versus 1,3,5-trimethylhexahydro-1,3,5-triazine (TMTZ). These results indicate that TMEDA and DMPipZ are excellent green replacements for hydrazines as the fuel in bipropellants.

  20. Thermodynamic characteristics of protolytic equilibria of hexamethylenediamine-N,N,N',N'-tetraacetic acid

    NASA Astrophysics Data System (ADS)

    Gridchin, S. N.; Pyreu, D. F.

    2011-04-01

    The heats of dissociation of betaine groups of hexamethylenediamine-N,N,N',N'-tetraacetic acid (H4L) at 298.15 K and the ionic strengths of 0.1, 0.5, and 1.0 (KNO3) were determined by direct calorimetry. The standard thermodynamic characteristics of the ptotolytic equilidria of H4L were calculated using the results from thermochemical and potentiometric measurements made under identical test conditions.

  1. Simulation of GaN and InGaN p i n and n i n photo-devices

    NASA Astrophysics Data System (ADS)

    Poochinda, Kunakorn; Chen, Tai-Chang; Stoebe, Thomas G.; Ricker, N. Lawrence

    2004-01-01

    Gallium nitride (GaN) and related materials have attracted an intense interest in their potential applications in high-power switching, high-temperature, and high-frequency device applications. A major advantage of the GaN system for optical applications is that the energy band gap can be reduced by alloying with InN. The InGaN alloy can provide a coverage from the near UV to the near infrared, including the visible spectrum. This research will provide the photonic and electrical properties of InGaN photo-devices by simulation. GaN and InGaN photo-devices, such as p-i-n and n-i-n devices, were simulated using ATHENA and ATLAS developed by Silvaco International, Inc. The spectral responsivity and the dark current were evaluated. These simulation results are comparable to the experimental result by Kung et al. with a 400×400 μm mesa structure of p-i-n GaN (SPIE 3287 (1998) 214). Since the heavily p-doping is still relatively hard to achieve currently, n-i-n photo-devices are evaluated and compared to p-i-n devices.

  2. 40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.7270 1-propanaminium, 3-amino-, N,N,N-trimethyl-N...

  3. 40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.7270 1-propanaminium, 3-amino-, N,N,N-trimethyl-N...

  4. 40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.7270 1-propanaminium, 3-amino-, N,N,N-trimethyl-N...

  5. 40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL... Significant New Uses for Specific Chemical Substances § 721.7270 1-propanaminium, 3-amino-, N,N,N-trimethyl-N...

  6. On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for InGaN/GaN light-emitting diodes.

    PubMed

    Kyaw, Zabu; Zhang, Zi-Hui; Liu, Wei; Tan, Swee Tiam; Ju, Zhen Gang; Zhang, Xue Liang; Ji, Yun; Hasanov, Namig; Zhu, Binbin; Lu, Shunpeng; Zhang, Yiping; Sun, Xiao Wei; Demir, Hilmi Volkan

    2014-01-13

    N-GaN/P-GaN/N-GaN/P-GaN/N-GaN (NPNPN-GaN) junctions embedded between the n-GaN region and multiple quantum wells (MQWs) are systematically studied both experimentally and theoretically to increase the performance of InGaN/GaN light emitting diodes (LEDs) in this work. In the proposed architecture, each thin P-GaN layer sandwiched in the NPNPN-GaN structure is completely depleted due to the built-in electric field in the NPNPN-GaN junctions, and the ionized acceptors in these P-GaN layers serve as the energy barriers for electrons from the n-GaN region, resulting in a reduced electron over flow and enhanced the current spreading horizontally in the n- GaN region. These lead to increased optical output power and external quantum efficiency (EQE) from the proposed device.

  7. Neutronics analysis for HYLIFE-II

    SciTech Connect

    Tobin, M.T.

    1990-12-20

    A preliminary neutronics analysis of the HYLIFE-2 reactor concept gives a tritium breeding ratio of 1.17 and a system energy multiplication factor of 1.14. Modified SS-316 (in which Mn is substituted for Ni) is superior to Hastelloy X and Hastelloy N as a firstwall material considering He generation, dpa-limited lifetime, and shallow-burial index. Since Flibe is corrosive to Mn metals, however, a favorable first-wall material is yet to be decided on. Flibe impurities considered (e.g., inherent impurities and those arising from wall erosion or secondary-coolant leakage) do not increase the hazard to the public over that of pure Flibe. The main issues for HYLIFE-2 are the high shallow-burial index (106) and the requirement to contain some 99.7% of the {sup 18}F inventory to prevent its release to the public 18 refs., 3 figs., 9 tabs.

  8. Effect of moisture on corrosion of Ni-based alloys in molten alkali fluoride FLiNaK salt environments

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Chang, Chi-Hung; You, Bo-Chien; Yeh, Tsung-Kuang; Kai, Ji-Jung

    2013-06-01

    We investigated the corrosion characteristics on several selected alloys at 600 and 700 °C in FLiNaK molten salts with different moisture contents. Hastelloys-N and Hastelloys-B3 exhibited better corrosion resistances, while Haynes 263 showed the poorest corrosion resistance. The mass loss of the tested alloys is primarily determined by the purity of FLiNaK salts; however, the effect of temperature becomes more important on the mass loss of the tested alloys in the non-purified FLiNaK salts. When the residual moisture is present in the FLiNaK salts, the mass losses of the tested alloys varied linearly with original Cr content plus one-third of Mo content. The results of structural characterization revealed that the tested alloys in the FLiNaK salts with higher moisture content would aggravate intergranular corrosion and pitting.

  9. 40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment...-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. (a) Chemical substance and significant new uses...-dimethyl-, N-soya acyl derivs., chlorides (PMN P-03-47; CAS No. 90194-13-1) is subject to reporting...

  10. "N" is for Now

    ERIC Educational Resources Information Center

    Briggs, Linda L.

    2008-01-01

    The leap in wireless LAN standards to 802.11n is a WiFi upgrade so new it has not yet garnered final approval from the standards committee. Although that approval will not come until next year (vendors are currently building to a "pre-n" standard), there are plenty of notebook computers out there capable of running 802.11n. That means students…

  11. "N" is for Now

    ERIC Educational Resources Information Center

    Briggs, Linda L.

    2008-01-01

    The leap in wireless LAN standards to 802.11n is a WiFi upgrade so new it has not yet garnered final approval from the standards committee. Although that approval will not come until next year (vendors are currently building to a "pre-n" standard), there are plenty of notebook computers out there capable of running 802.11n. That means students…

  12. Thermodynamic characteristics of the protolytic equilibria of tetramethylenediamine- N,N,N', N'-tetraacetic acid

    NASA Astrophysics Data System (ADS)

    Gridchin, S. N.; Nikol'skii, V. M.

    2014-04-01

    The stepwise dissociation constants of tetramethylenediamine- N,N,N', N'-tetraacetic acid (H4L) are determined by means of potentiometry at 298.15 K and ionic strength values of 0.1, 0.5, and 1.0 (KNO3). The heat effects of the dissociation of the betaine groups of the complexone are measured by direct calorimetry. The standard thermodynamic characteristics of the protolytic equilibria of H4L are calculated via combined use of the results from thermochemical and potentiometric studies performed under identical experimental conditions. Our results are compared with the corresponding data on relative compounds.

  13. Crystal structure of N-[3-(di-methyl-aza-nium-yl)prop-yl]-N',N',N'',N''-tetra-methyl-N-(N,N,N',N'-tetra-methyl-form-am-id-in-ium-yl)-guanidinium dibromide hydroxide monohydrate.

    PubMed

    Tiritiris, Ioannis; Kantlehner, Willi

    2015-12-01

    The asymmetric unit of the title hydrated salt, C15H37N6 (3+)·2Br(-)·OH(-)·H2O, contains one cation, three partial-occupancy bromide ions, one hydroxide ion and one water mol-ecule. Refinement of the site-occupancy factors of the three disordered bromide ions converges with occupancies 0.701 (2), 0.831 (2) and 0.456 (2) summing to approximately two bromide ions per formula unit. The structure was refined as a two-component inversion twin with volume fractions 0.109 (8):0.891 (8) for the two domains. The central C3N unit of the bis-amidinium ion is linked to the aliphatic propyl chain by a C-N single bond. The other two bonds in this unit have double-bond character as have the four C-N bonds to the outer NMe2 groups. In contrast, the three C-N bonds to the central N atom of the (di-methyl-aza-nium-yl)propyl group have single-bond character. Delocalization of the two positive charges occurs in the N/C/N and C/N/C planes, while the third positive charge is localized on the di-methyl-ammonium group. The crystal structure is stabilized by O-H⋯O, N-H⋯Br, O-H⋯Br and C-H⋯Br hydrogen bonds, forming a three-dimensional network.

  14. Coupling constant for N*(1535)N{rho}

    SciTech Connect

    Xie Jujun; Wilkin, Colin; Zou Bingsong

    2008-05-15

    The value of the N*(1535)N{rho} coupling constant g{sub N*N{rho}} derived from the N*(1535){yields}N{rho}{yields}N{pi}{pi} decay is compared with that deduced from the radiative decay N*(1535){yields}N{gamma} using the vector-meson-dominance model. On the basis of an effective Lagrangian approach, we show that the values of g{sub N*N{rho}} extracted from the available experimental data on the two decays are consistent, though the error bars are rather large.

  15. Neuropharmacology of N,N-Dimethyltryptamine

    PubMed Central

    Carbonaro, Theresa M.; Gatch, Michael B.

    2016-01-01

    N,N-Dimethyltryptamine (DMT) is an indole alkaloid widely found in plants and animals. It is best known for producing brief and intense psychedelic effects when ingested. Increasing evidence suggests that endogenous DMT plays important roles for a number of processes in the periphery and central nervous system, and may act as a neurotransmitter. This paper reviews the current literature of both the recreational use of DMT and its potential roles as an endogenous neurotransmitter. Pharmacokinetics, mechanisms of action in the periphery and central nervous system, clinical uses and adverse effects are also reviewed. DMT appears to have limited neurotoxicity and other adverse effects except for intense cardiovascular effects when administered intravenously in large doses. Because of its role in nervous system signaling, DMT may be a useful experimental tool in exploring how brain works, and may also be a useful clinical tool for treatment of anxiety and psychosis. PMID:27126737

  16. Neuropharmacology of N,N-dimethyltryptamine.

    PubMed

    Carbonaro, Theresa M; Gatch, Michael B

    2016-09-01

    N,N-dimethyltryptamine (DMT) is an indole alkaloid widely found in plants and animals. It is best known for producing brief and intense psychedelic effects when ingested. Increasing evidence suggests that endogenous DMT plays important roles for a number of processes in the periphery and central nervous system, and may act as a neurotransmitter. This paper reviews the current literature of both the recreational use of DMT and its potential roles as an endogenous neurotransmitter. Pharmacokinetics, mechanisms of action in the periphery and central nervous system, clinical uses and adverse effects are also reviewed. DMT appears to have limited neurotoxicity and other adverse effects except for intense cardiovascular effects when administered intravenously in large doses. Because of its role in nervous system signaling, DMT may be a useful experimental tool in exploring how the brain works, and may also be a useful clinical tool for treatment of anxiety and psychosis.

  17. Unified theory of γN-->πN,ππN, and πN-->πN,ππN reactions

    NASA Astrophysics Data System (ADS)

    Afnan, I. R.

    1988-10-01

    We present a set of coupled integral equations for the reactions γN-->πN,ππN and πN-->πN,ππN, that satisfy two- and three-body unitarity. These equations are based on a chiral bag Lagrangian in which the coupling to the photon is introduced at the quark level by demanding U(1) local gauge invariance. The final equations include the contribution of both meson exchange and isobar currents.

  18. 40 CFR 721.9957 - N-Nitroso-N-methylurethane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false N-Nitroso-N-methylurethane. 721.9957... Substances § 721.9957 N-Nitroso-N-methylurethane. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance N-nitroso-N-methylurethane (CAS No. 615-53-2) is subject to reporting...

  19. 40 CFR 721.9957 - N-Nitroso-N-methylurethane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false N-Nitroso-N-methylurethane. 721.9957... Substances § 721.9957 N-Nitroso-N-methylurethane. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance N-nitroso-N-methylurethane (CAS No. 615-53-2) is subject to reporting...

  20. 40 CFR 721.9957 - N-Nitroso-N-methylurethane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false N-Nitroso-N-methylurethane. 721.9957... Substances § 721.9957 N-Nitroso-N-methylurethane. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance N-nitroso-N-methylurethane (CAS No. 615-53-2) is subject to reporting...

  1. Classification of (n+3)-dimensional metric n-Lie algebras

    SciTech Connect

    Geng Qiaozhi; Ren Mingming; Chen Zhiqi

    2010-10-15

    In this paper, we focus on (n+3)-dimensional metric n-Lie algebras. To begin with, we give some properties on (n+3)-dimensional n-Lie algebras. Then based on the properties, we obtain the classification of (n+3)-dimensional metric n-Lie algebras.

  2. 40 CFR 721.9957 - N-Nitroso-N-methylurethane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false N-Nitroso-N-methylurethane. 721.9957... Substances § 721.9957 N-Nitroso-N-methylurethane. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance N-nitroso-N-methylurethane (CAS No. 615-53-2) is subject to...

  3. 40 CFR 721.9957 - N-Nitroso-N-methylurethane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false N-Nitroso-N-methylurethane. 721.9957... Substances § 721.9957 N-Nitroso-N-methylurethane. (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance N-nitroso-N-methylurethane (CAS No. 615-53-2) is subject to reporting...

  4. The n = 0 Discovery

    NASA Astrophysics Data System (ADS)

    Witten, Thomas A.

    We describe Pierre-Gilles de Gennes' 1972 letter explaining polymer swelling as a form of critical phenomenon. We trace the impact of this "n = 0" discovery on polymer theory and experiment. We discuss later developments in mainstream statistical physics that reflect the n = 0 insight of this paper. We collect the views of several leading statistical physicists on the significance of the discovery.

  5. Eastman N. Jacobs

    NASA Technical Reports Server (NTRS)

    1945-01-01

    Sylvanus Albert Reed Award: Eastman N. Jacobs: In 1937, Eastman N. Jacobs, one of Langley's most adventurous researchers, received the Sylvanus Albert Reed Award for his contributions to the aerodynamic improvement of airfoils. Published in James R. Hansen, Engineer in Charge, NASA SP- 4305, p. 106.

  6. Radiación

    NASA Image and Video Library

    Fuera del capullo protector de la atmósfera terrestre, el universo está plagado de radiación dañina. Los astronautas que viven y trabajan en el espacio están expuestos no sólo a los rayos ultraviol...

  7. 2 n -rational maps

    NASA Astrophysics Data System (ADS)

    Kassotakis, Pavlos; Nieszporski, Maciej

    2017-05-01

    We present a natural extension of the notion of nondegenerate rational maps (quadrirational maps) to arbitrary dimensions. We refer to these maps as 2 n -rational maps. In this note we construct a rich family of 2 n -rational maps. These maps by construction are involutions and highly symmetric in the sense that the maps and their companion maps have the same functional form.

  8. N Reactor hydrogen control

    SciTech Connect

    Shuford, D.H.; Kripps, L.J.

    1988-08-01

    Following the accident at the Chernobyl nuclear power reactor in the Soviet Union, a number of reviews were conducted of the N Reactor. Hydrogen generation during postulates severe accidents and the possibility of resulting hydrogen deflagrations/detonations that could affect confinement integrity were issues raised in several reviews, along with recommendations for adding hydrogen mitigation features. To respond to these reviews, an N Reactor Safety Enhancement Program and a subsequent Accelerated Safety Enhancement Program were initiated to address all post-Chernobyl N Reactor review findings. The Safety Enhancement Program and Accelerated Safety Enhancement Program efforts involving hydrogen control included the following: Calculate the potential hydrogen source for a range of severe accidents at the N Reactor to establish an acceptable design basis for the hydrogen mitigation system; Analyze the N Reactor confinement hydrogen mixing capability to identify areas of concern and to the verify effectiveness of the hydrogen mitigation system; Select, design, and construct a hydrogen mitigation system to enhance the N Reactor capability to accommodate possible hydrogen generation from postulated severe accidents; Provide post-accident hydrogen monitoring as an operator aid in assessing confinement conditions. In additions, it was necessary to verify that incorporation of the hydrogen mitigation system had no adverse impact N Reactor safety (e.g., radiological consequence analyses). 77 refs., 25 figs., 10 tabs.

  9. Pulsed terahertz emission from GaN/InN heterostructure

    NASA Astrophysics Data System (ADS)

    Reklaitis, Antanas

    2011-11-01

    Dynamics of the electron-hole plasma excited by the femtosecond optical pulse in wurtzite GaN/InN heterostructure is investigated by Monte Carlo simulations. The GaN/InN heterostructure for pulsed terahertz emission is suggested. The results of Monte Carlo simulations show that the power of terahertz emission from the GaN/InN heterostructure exceeds the power of terahertz emission from the surface of InN by one order of magnitude.

  10. GaN HEMTs

    NASA Astrophysics Data System (ADS)

    Anderson, Jonathan W.; Lee, Kyoung-Keun; Piner, Edwin L.

    2012-03-01

    Gallium nitride (GaN) has enormous potential for applications in high electron mobility transistors (HEMTs) used in RF and power devices. Intrinsic device properties such as high electron mobility, high breakdown voltage, very high current density, electron confinement in a narrow channel, and high electron velocity in the 2-dimensional electron gas of the HEMT structure are due in large part to the wide band gap of this novel semiconductor material system. This presentation discusses the properties of GaN that make it superior to other semiconductor materials, and outlines the research that will be undertaken in a new program at Texas State University to advance GaN HEMT technology. This program's aim is to further innovate the exceptional performance of GaN through improved material growth processes and epitaxial structure design.

  11. N+2 Nozzle Test

    NASA Image and Video Library

    2016-12-09

    N+2 Nozzle in the Aero-Acoustic Propulsion Lab. As NASA works toward demonstrating low-sonic boom design, engineers at NASA Glenn have tested an engine nozzle that could make supersonic aircraft much quieter.

  12. N + 2 Nozzle Test

    NASA Image and Video Library

    2016-12-09

    N+2 Nozzle in the Aero-Acoustic Propulsion Lab. As NASA works toward demonstrating low-sonic boom design, engineers at NASA Glenn have tested an engine nozzle that could make supersonic aircraft much quieter.

  13. Weyl n-Algebras

    NASA Astrophysics Data System (ADS)

    Markarian, Nikita

    2017-03-01

    We introduce Weyl n-algebras and show how their factorization complex may be used to define invariants of manifolds. In the appendix, we heuristically explain why these invariants must be perturbative Chern-Simons invariants.

  14. Aggregation of N,N'-diallylurea and N,N'-diallylthiourea in solutions.

    PubMed

    Rospenk, Maria; Obrzud, Monika; Koll, Aleksander

    2017-11-05

    Joint studies by IR spectroscopy, dipole moments, average molecular weight measurements and DFT calculations on the self-aggregation of N,N'-diallylureas and N,N'-diallylthioureas in solvents of different polarities were performed. Simultaneous uses of all these methods are required for better understanding the mechanism of aggregation and the effects of different polarity of solvents. In this study also the measurements of IR spectra in polarized light were additionally performed, which gives information on arrangement of aggregates in liquid crystal matrix-built of 4-CN biphenyl derivative. It was demonstrated that in such conditions two forms of dimers the linear and cyclic ones are in equilibrium with different arrangements according the axis of CN group. Copyright © 2017. Published by Elsevier B.V.

  15. N,N-Dimethyltryptamine-Induced Psychosis.

    PubMed

    Paterson, Neil E; Darby, W Connor; Sandhu, Preetpal S

    2015-01-01

    N,N-dimethyltryptamine (DMT) is a 5-hydroxytryptamine 2A and 1A receptor agonist that exhibits potent psychoactive properties in humans. Recreational use of this drug has increased precipitously and is likely to result in an increase in patients presenting with substance-induced psychoses. The present case provides an early example of substance-induced psychosis attributable to repeated use of DMT. A 42-year-old white man, with no significant past psychiatric history, was brought to the emergency department by the police and was found to exhibit disinhibited behavior, elevated affect, disorganized thought process, and delusions of reference. Laboratory studies revealed elevated creatinine kinase level indicative of rhabdomyolysis. The patient endorsed recent and repeated use of DMT, as well as long-term Cannabis (marijuana) use. Over the course of the next 3 weeks, the patient was successfully treated with quetiapine for psychosis, divalproex sodium (Depakote) for impulsivity, gabapentin for anxiety, and hydroxyzine for sleep, which resulted in the resolution of his symptoms and development of reasonable insight and judgment. Approximately 6 months after discharge, the patient remained treatment compliant, as well as drug and symptom free. This case report illustrates an important example of substance-induced psychosis that resolved with antipsychotic treatment in a 42-year-old white man with no past psychiatric history likely attributable to the use of DMT. Given the increasing use of this substance, the emergency department, primary care, and inpatient services are likely to see a significant increase in similar cases.

  16. Human psychopharmacology of N,N-dimethyltryptamine.

    PubMed

    Strassman, R J

    1996-01-01

    We generated dose-response data for the endogenous and ultra-short-acting hallucinogen, N,N-dimethyltryptamine (DMT), in a cohort of experienced hallucinogen users, measuring multiple biological and psychological outcome measures. Subjective responses were quantified with a new rating scale, the HRS, which provided better resolution of dose effects than did the biological variables. A tolerance study then was performed, in which volunteers received four closely spaced hallucinogenic doses of DMT. Subjective responses demonstrated no tolerance, while biological measures were inconsistently reduced over the course of the sessions. Thus, DMT remains unique among classic hallucinogens in its inability to induce tolerance to its psychological effects. To assess the role of the 5-HT1A site in mediating DMT's effects, a pindolol pre-treatment study was performed. Pindolol significantly increased psychological responses to DMT, suggesting a buffering effect of 5-HT1A agonism on 5-HT2-mediated psychedelic effects. These data are opposite to those described in lower animal models of hallucinogens' mechanisms of action.

  17. SUq( n) gauge theory

    NASA Astrophysics Data System (ADS)

    Sudbery, Anthony

    1996-02-01

    A field theory with local transformations belonging to the quantum group SUq( n) is defined on a classical spacetime, with gauge potentials belonging to a quantum Lie algebra. Gauge transformations are defined for the potentials which lead to the appropriate quantum-group transformations for field strengths and covariant derivatives, defined for all elements of SUq( n) by means of the adjoint action. This guarantees a non-trivial deformation. Gauge-invariant commutation relations are identified.

  18. Electron states at electrolyte/n-GaN and electrolyte/n-InGaN interfaces

    SciTech Connect

    Rudinsky, M. E. Gutkin, A. A.; Brunkov, P. N.

    2012-06-15

    The differential capacitance and differential active conductance of rectifying contacts of n-GaN and n-In{sub x}Ga{sub 1-x}N (x Almost-Equal-To 0.15) with an electrolyte (0.2 M aqueous solutions of NaOH, NaCl, or HCl) have been studied. It was found that electron states with energies corresponding to the upper half of the energy gap of a semiconductor exist at the interface between these semiconductors and a NaOH solution. The density and characteristic recharging time of states noticeably contributing to the differential capacitance and differential active conductance at probe-voltage frequencies of 0.3-1 kHz grow with their binding energy and, for states lying at 0.15-0.3 eV below the conduction-band bottom of n-GaN, fall within the ranges 10{sup 12}-2 Multiplication-Sign 10{sup 13} cm{sup -2} eV{sup -1} and 10{sup -4}-10{sup -2} s, respectively. For contacts with NaCl and HCl solutions, there are no states of this kind. It is assumed that the observed states are related to the adsorption of hydroxyl groups.

  19. N,N-Dibenzoyl­ferrocenecarboxamide

    PubMed Central

    Cetina, Mario; Kovač, Veronika; Rapić, Vladimir

    2011-01-01

    In the title compound, [Fe(C5H5)(C20H14NO3)], the cyclo­penta­dienyl rings deviate by 9.3 (2)° from an eclipsed conformation, defined by C—Cg 1—Cg 2—C pseudo-torsion angles ranging from 8.8 (1) to 9.85 (1)°. The coordination at the N atom is slightly pyramidal, as indicated by the angular sum around it of 352.6°. The amide group is inclined at 17.86 (9) and 27.27 (11)° with respect to the aromatic rings. In the crystal, mol­ecules are linked by one C—H⋯O hydrogen bond and one C—H⋯π inter­action into a two-dimensional framework parallel to the b axis. PMID:21754327

  20. African N Assessment

    NASA Astrophysics Data System (ADS)

    Bekunda, M.; Galford, G. L.; Hickman, J. E.; Palm, C.

    2011-12-01

    Africa's smallholder agricultural systems face unique challenges in planning for reducing poverty, concurrent with adaptation and mitigation to climate change. At continental level, policy seeks to promote a uniquely African Green Revolution to increase crop yields and food production, and improve local livelihoods. However, the consequences on the environment and climate are not clear; these pro-economic development measures should be linked to climate change adaptation and mitigation measures, and research is required to help achieve these policy proposals by identifying options, and testing impacts. In particular, increased nitrogen (N) inputs are essential for increasing food production in Africa, but are accompanied by inevitable increases in losses to the environment. These losses appear to be low at input levels promoted in agricultural development programs, while the increased N inputs both increase current food production and appear to reduce the vulnerability of food production to changes in climate. We present field and remote sensing evidence from Malawi that subsidizing improved seed and fertilizers increases resilience to drought without adding excess N to the environment. In Kenya, field research identified thresholds in N2O losses, where emissions are very low at fertilization rates of less than 200 kg ha-1. Village-scale models have identified potential inefficiencies in the food production process where the largest losses of reactive N occur, and which could be targeted to reduce the amount of N released to the environment. We further review some on-going research activities and progress in Africa that compare different methods of managing resources that target resilience in food production and adaptation to climate change, using nutrient N as an indicator, while evaluating the effects of these resource management practices on ecosystems and the environment.

  1. High-Precision Measurements of 15N15N, 14N15N, and 14N2 in N2 and Potential Applications to Oceanic Nitrogen Cycle Research

    NASA Astrophysics Data System (ADS)

    Li, S.; Yeung, L.; Young, E. D.; Ostrom, N. E.; Haslun, J. A.

    2016-02-01

    The balance of nitrogen fixation and nitrogen loss in the oceans is uncertain. For example, anaerobic ammonia oxidation could account for 50% or more of marine N2 production, although its global importance is still poorly known. Isotopic ratios in fixed nitrogen species (e.g., δ15N and δ18O values of NO2- and NO3-) are widely used to trace preservation and removal of N-bearing compounds and/or isotopic variations of their different sources. However, these approaches in general probe only one side of the nitrogen mass balance—the "fixed" nitrogen reservoir—so they offer few constraints on the ultimate loss of nitrogen from that pool as N2. The rare isotopologue ratio 15N15N/14N2 in N2may provide information about those nitrogen-loss processes directly. We will report the first measurements of Δ30 (the abundance of 15N15N relative to that predicted by chance alone), made on a unique high-resolution mass spectrometer (the Nu Instruments Panorama), and we will discuss the potential utility of Δ30 as an independent tracer of the nitrogen cycle. The parameter Δ30 is insensitive to the bulk 15N/14N isotopic ratio of the reservoir; instead, it reflects isotopic ordering in N2, which is altered when N-N bonds are made or broken. Our preliminary measurements of N2 from denitrifying soils and pure cultures of denitrifiers indicate large kinetic isotopic effects during N-N bond formation that favor 15N15N production during denitrification. We also observed a nonstochastic excess of 15N15N in tropospheric N2 [Δ30 = +19.05 ± 0.12‰ (1σ)]. This excess likely comes from fixed-nitrogen loss processes in the biosphere. Variations in Δ30 of N2 from pure culture experiments (+16.96 to +18.95‰) probably reflect the different isotopic signatures of the enzymes that catalyze denitrification. So, enzyme-specific Δ30 values of dissolved N2 should provide information about the importance of different biochemical pathways of fixed-nitrogen loss (e.g., denitrification vs

  2. p -n Junction Rectifying Characteristics of Purely n -Type GaN-Based Structures

    NASA Astrophysics Data System (ADS)

    Zuo, P.; Jiang, Y.; Ma, Z. G.; Wang, L.; Zhao, B.; Li, Y. F.; Yue, G.; Wu, H. Y.; Yan, H. J.; Jia, H. Q.; Wang, W. X.; Zhou, J. M.; Sun, Q.; Liu, W. M.; Ji, An-Chun; Chen, H.

    2017-08-01

    The GaN-based p -n junction rectifications are important in the development of high-power electronics. Here, we demonstrate that p -n junction rectifying characteristics can be realized with pure n -type structures by inserting an (In,Ga)N quantum well into the GaN /(Al ,Ga )N /GaN double heterostructures. Unlike the usual barriers, the insertion of an (In,Ga)N quantum well, which has an opposite polarization field to that of the (Al,Ga)N barrier, tailors significantly the energy bands of the system. The lifted energy level of the GaN spacer and the formation of the (In ,Ga )N /GaN interface barrier can improve the reverse threshold voltage and reduce the forward threshold voltage simultaneously, forming the p -n junction rectifying characteristics.

  3. N_2(+) in Comets?

    NASA Astrophysics Data System (ADS)

    Cochran, A. L.; Barker, E. S.; Cochran, W. D.

    1999-09-01

    Comets delivered some of the volatiles that we see today in the atmospheres of the terrestrial planets, but it is not certain how important a source of volatiles the comets represent. In order to ascertain the relative importance of comets as a source of volatiles, it is necessary to understand the volatile abundances of comets. Owen and Bar-Nun (Icarus 116, 215, 1995) have pointed out that nitrogen is an important guide to the volatile abundances of comets because it is trapped and released by amorphous ice in a manner which is similar to argon. Since nitrogen is cosmically abundant and can exist in a variety of molecules with varying amounts of volatility, it can be compared with several reservoirs of ices in astronomical sources. However, measuring the N_2 content of cometary comae is extremely difficult because the available transitions are few, and the Earth's atmosphere contains significant quantities of N_2. In the past, the (0,0) transition of N_2(+) has been reported in the spectra of comets. This transition occurs at approximately 3900 Angstroms. However, care must be taken when observing this transition because N_2(+) is excited in the atmosphere of the Earth, especially near dusk and dawn when comets are often observed. Thus, accurate measurement of N_2(+) in cometary spectra requires both good spatial and spectral resolution to separate the features from that of the Earth. We obtained high S/N spectra of Hale-Bopp at R=200,000 and at several distances into the tail in order to place hard limits on the N_2(+) in the coma of this comet. In addition, we obtained excellent observations of comet de Vico, both of the optocenter and the tail. There is no clear detection of N_2(+) in either of these comets. We report on our observations and on the limits we can place on N_2(+) in these comets and compare them with previous observations. This work was supported by NASA Grant NAG5 4208.

  4. 40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10056 Benzenemethanaminium, N-(3...

  5. 40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10056 Benzenemethanaminium, N-(3...

  6. 40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10056 Benzenemethanaminium, N-(3...

  7. N-methylated tryptamine derivatives in citrus genus plants: identification of N,N,N-trimethyltryptamine in bergamot.

    PubMed

    Servillo, Luigi; Giovane, Alfonso; Balestrieri, Maria Luisa; Cautela, Domenico; Castaldo, Domenico

    2012-09-19

    The occurrence of N-methylated tryptamine derivatives in bergamot plant (Citrus bergamia Risso et Poit) is reported for the first time. Interestingly, the most abundant of these substances is N,N,N-trimethyltryptamine, which has not been previously identified in any citrus plant. The N-methylated tryptamine derivatives were identified and quantitated in leaves, peel, juice, and seeds by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. N,N,N-Trimethyltryptamine was confirmed by MS(3) and comparison with the synthesized authentic standard. In addition, the study of the distribution of tryptophan, tryptamine, N-methyltryptamine, N,N-dimethyltryptamine, and N,N,N-trimethyltryptamine indicated that these compounds are differently expressed in the various tissues of the bergamot plant. Intriguingly, chemically synthesized N,N,N-trimethyltryptamine was reported to possess nicotine-like activity being a stimulant of parasympathetic ganglia by exerting its action on acetylcholine receptors. On this basis, the identification of N,N,N-trimethyltryptamine at a relatively high level in leaves suggests a possible role in a physiological mechanism of plant defense.

  8. 40 CFR 721.10056 - Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzenemethanaminium, N-(3-aminopropyl)-N,N-dimethyl-, N-soya acyl derivs., chlorides. 721.10056 Section 721.10056 Protection of Environment... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10056 Benzenemethanaminium, N-(3...

  9. 40 CFR 721.7270 - 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl derivs., chloride.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-trimethyl-N-soya acyl derivs., chloride. 721.7270 Section 721.7270 Protection of Environment ENVIRONMENTAL...-soya acyl derivs., chloride. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-propanaminium, 3-amino-, N,N,N-trimethyl-N-soya acyl...

  10. 40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts (PMN...

  11. 40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts (PMN...

  12. 40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts (PMN...

  13. 40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts (PMN...

  14. Conformations in unsymmetrically N-n-propyl-N-substituted 2-phenylacetamides

    NASA Astrophysics Data System (ADS)

    Antonović, D. G.; Vajs, V. E.; Stojanović, N. D.; Nikolić, A. D.; Petrović, S. D.

    1992-03-01

    As a part of a study on the structural characteristics of some new various N-alkyl-N-substituted 2-phenylacetamides the infrared and 1H N.M.R. spectra were obtained and interpreted. The synthesis of a various N-n-propyl-N-alkyl 2-phenylacetamides of the general formula PhCH 2CON(nPr)R, wherein R is ethyl, isopropyl, n-butyl, t-butyl and cyclohexyl, were performed. The corresponding mixed secondary amines of the type HNnPrR were obtained by catalytic hydrogenation of the synthetized propylidenealkylamines. The 1H N.M.R. spectra of these unsymmetrically N,N-disubstituted amides have been studied and the peaks have been assigned in each cases to two possible conformational isomers, arising from the lack of free rotation about the C(O)N bond. These results are in accordance with our previous investigation of the structure of N-substituted 2-phenylacetamides.

  15. 1989N1

    NASA Image and Video Library

    1996-01-29

    NASA's Voyager 2 took this image of Neptune's irregularly-shaped satellite 1989N1 from a range of 870,000 kilometers (540,000 miles). The resolution is 8 kilometers (5 miles) per pixel. The satellite has an average radius of about 200 kilometers (120 miles) and is uniformly dark with an albedo of about 6 percent. The irregular shape suggests that 1989N1 has been cold and rigid throughout its history and subject to significant impact cratering. http://photojournal.jpl.nasa.gov/catalog/PIA00055

  16. N-methylated derivatives of tyramine in citrus genus plants: identification of N,N,N-trimethyltyramine (candicine).

    PubMed

    Servillo, Luigi; Giovane, Alfonso; D'Onofrio, Nunzia; Casale, Rosario; Cautela, Domenico; Ferrari, Giovanna; Balestrieri, Maria Luisa; Castaldo, Domenico

    2014-03-26

    The distribution of tyramine and its methylated derivatives, N-methyltyramine and N,N-dimethyltyramine, was investigated in tissue parts (leaves and fruits) of several plants of Citrus genus by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). In the course of our study we discovered the occurrence of N,N,N-trimethyltyramine in all citrus plants examined. This quaternary ammonium compound, known to act in animals as a neurotoxin, was recognized and characterized by mass spectrometric analysis. The substance, never described before in the Citrus genus, is also known as candicine or maltoxin. Results indicate that N,N,N-trimethyltyramine is consistently expressed in leaves of clementine, bitter orange, and lemon. Conversely, low levels were found in the leaves of orange, mandarin, chinotto (Citrus myrtifolia), bergamot, citron, and pomelo. In the edible part of the fruits, N,N,N-trimethyltyramine was found at trace levels.

  17. (μ-2-Pyridine-aldazine-κN,N':N'',N''')bis-[bis-(N,N-di-n-propyl-dithio-carbamato-κS,S')cadmium(II)].

    PubMed

    Poplaukhin, Pavel; Tiekink, Edward R T

    2008-08-16

    The dinuclear centrosymmetric title compound, [Cd(2)(C(7)H(14)NS(2))(4)(C(12)H(10)N(4))], features a tetra-dentate 2-pyridine-aldazine ligand that chelates two Cd centres. The coordination geometry for Cd is distorted octa-hedral based on a cis-N(2)S(4) donor set. In the crystal structure, mol-ecules are connected into a supra-molecular chain aligned along the a direction via C-H⋯S and C-H⋯π contacts, and by π-π contacts [centroid-to-centroid distance 3.5708 (15) Å]. The n-propyl groups are each disordered, one equally over two sites and the other with a site-occupancy factor of 0.618 (8) for the major component.

  18. N-Nitrosodimethylamine

    Integrated Risk Information System (IRIS)

    N - Nitrosodimethylamine ; CASRN 62 - 75 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcin

  19. N-Nitrosodiethylamine

    Integrated Risk Information System (IRIS)

    N - Nitrosodiethylamine ; CASRN 55 - 18 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcino

  20. n-Heptane

    Integrated Risk Information System (IRIS)

    n - Heptane ; CASRN 142 - 82 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  1. The Bubble N10

    NASA Astrophysics Data System (ADS)

    Gama, D.; Lepine, J.; Wu, Y.; Yuan, J.

    2014-10-01

    We studied the environment surrounding the infrared bubble N10 in molecular and infrared emission. There is an HII region at the center of this bubble. We investigated J=1-0 transitions of molecules ^{12}CO, ^{13}CO and C^{18}O towards N10. This object was detected by GLIMPSE, a survey carried out between 3.6 and 8.0 μ m. We also analyzed the emission at 24 μ m, corresponding to the emission of hot dust, with a contribution of small grains heated by nearby O stars. Besides, the contribution at 8 μ m is dominated by PAHs (polycyclic aromatic hydrocarbons) excited by radiation from the PDRs of bubbles. In the case of N10, it is proposed that the excess at 4.5 μ m IRAC band indicate an outflow, a signature of early stages of massive star formation. This object was the target of observations at the PMO 13.7 m radio telescope. The bubble N10 presents clumps, from which we can derive physical features through the observed parameters. We also intended to discuss the evolutionary stage of the clumps and their distribution. It can lead us to understand the triggered star formation scenario in this region.

  2. The "N" Word.

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    1999-01-01

    In a lawsuit involving classroom and literary racial epithets, the Ninth Circuit Court remanded the racial-harassment claim, not the book-removal claim. The ultimate outcome awaits trial; the court's Solomonic decision needs further testing. Meanwhile, the "N" word is a no-no for teachers and students, but not necessarily for books. (MLH)

  3. n-Hexane

    Integrated Risk Information System (IRIS)

    EPA / 635 / R - 03 / 012 www.epa.gov / iris TOXICOLOGICAL REVIEW OF n - HEXANE ( CAS No . 110 - 54 - 3 ) In Support of Summary Information on the Integrated Risk Information System ( IRIS ) November 2005 U.S . Environmental Protection Agency Washington , DC DISCLAIMER This docum ent has been revie

  4. N-Nitrosodiethanolamine

    Integrated Risk Information System (IRIS)

    N - Nitrosodiethanolamine ; CASRN 1116 - 54 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncar

  5. N-Nitrosopyrrolidine

    Integrated Risk Information System (IRIS)

    N - Nitrosopyrrolidine ; CASRN 930 - 55 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcino

  6. N-Nitrosodiphenylamine

    Integrated Risk Information System (IRIS)

    N - Nitrosodiphenylamine ; CASRN 86 - 30 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcin

  7. n-Butanol

    Integrated Risk Information System (IRIS)

    n - Butanol ; CASRN 71 - 36 - 3 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effect

  8. Genotoxicity analysis of N,N-dimethylaniline and N,N-dimethyl-p-toluidine

    SciTech Connect

    Taningher, M. ); Bonatti, S. ); Pasquini, R. )

    1993-01-01

    N,N-Dimethylaniline (DMA, CAS No. 121-69-7) and N,N-dimethyl-p-toluidine (DMPT, CAS No. 99-97-8) belong to the N-dialkylaminoaromatics, a chemical class structurally alerting to DNA reactivity. Their applications may be industrial (dye and pesticide intermediates, polymerizing agents) and surgical (polymerization accelerations for the manufacture of bone cements and prosthetic devices), thus implying heterogeneous types of human exposure. Findings of carcinogenicity in rodents and some nonexhaustive genotoxicity data are available for DMA, but no information is available on DMPT concerning either carcinogenicity or any kind of genetic toxicity. To investigate their mechanism of action and mutagenic/carcinogenic potential, DMA and DMPT were analyzed for complementary genotoxicity endpoints, namely, gene mutation in Salmonella (Ames test), structural and numerical chromosome aberrations in hamster V79 cells (micronucleus test, matched with an immunofluorescent staining for kinetochore proteins), and in vivo DNA damage in mouse and rat liver (alkaline DNA elution test). The results essentially indicate that both chemicals are chromosome damaging agents. Indeed, at the maximum nontoxic doses, they proved nonmutagenic in Salmonella (although their toxicity did not allow concentrations > 70 [mu]g/plate to be tested) and weakly positive in inducing DNA damage (increases in DNA elution rates at most [approximately]2.4 times control value). Conversely, they proved clearly positive in inducing numerical chromosome alterations, with dose-dependent increases up to more than five times the control value for DMPT. At the highest dose tested, both chemicals also showed a significant clastogenic effect. 28 refs., 4 tabs.

  9. Epitaxial NbN/AlN/NbN tunnel junctions on Si substrates with TiN buffer layers

    SciTech Connect

    Sun, Rui; Makise, Kazumasa; Terai, Hirotaka; Zhang, Lu; Wang, Zhen

    2016-06-15

    We have developed epitaxial NbN/AlN/NbN tunnel junctions on Si (100) substrates with a TiN buffer layer. A 50-nm-thick (200)-oriented TiN thin film was introduced as the buffer layer for epitaxial growth of NbN/AlN/NbN trilayers on Si substrates. The fabricated NbN/AlN/NbN junctions demonstrated excellent tunneling properties with a high gap voltage of 5.5 mV, a large I{sub c}R{sub N} product of 3.8 mV, a sharp quasiparticle current rise with a ΔV{sub g} of 0.4 mV, and a small subgap leakage current. The junction quality factor R{sub sg}/R{sub N} was about 23 for the junction with a J{sub c} of 47 A/cm{sup 2} and was about 6 for the junction with a J{sub c} of 3.0 kA/cm{sup 2}. X-ray diffraction and transmission electron microscopy observations showed that the NbN/AlN/NbN trilayers were grown epitaxially on the (200)-orientated TiN buffer layer and had a highly crystalline structure with the (200) orientation.

  10. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance. N-(n-octyl)-2...

  11. 40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts (PMN P-03-46; CAS No. 136504-87-5) is subject...

  12. Noncompetitive inhibition of indolethylamine-N-methyltransferase by N,N-dimethyltryptamine and N,N-dimethylaminopropyltryptamine.

    PubMed

    Chu, Uyen B; Vorperian, Sevahn K; Satyshur, Kenneth; Eickstaedt, Kelsey; Cozzi, Nicholas V; Mavlyutov, Timur; Hajipour, Abdol R; Ruoho, Arnold E

    2014-05-13

    Indolethylamine-N-methyltransferase (INMT) is a Class 1 transmethylation enzyme known for its production of N,N-dimethyltryptamine (DMT), a hallucinogen with affinity for various serotonergic, adrenergic, histaminergic, dopaminergic, and sigma-1 receptors. DMT is produced via the action of INMT on the endogenous substrates tryptamine and S-adenosyl-l-methionine (SAM). The biological, biochemical, and selective small molecule regulation of INMT enzyme activity remain largely unknown. Kinetic mechanisms for inhibition of rabbit lung INMT (rabINMT) by the product, DMT, and by a new novel tryptamine derivative were determined. After Michaelis-Menten and Lineweaver-Burk analyses had been applied to study inhibition, DMT was found to be a mixed competitive and noncompetitive inhibitor when measured against tryptamine. The novel tryptamine derivative, N-[2-(1H-indol-3-yl)ethyl]-N',N'-dimethylpropane-1,3-diamine (propyl dimethyl amino tryptamine or PDAT), was shown to inhibit rabINMT by a pure noncompetitive mechanism when measured against tryptamine with a Ki of 84 μM. No inhibition by PDAT was observed at 2 mM when it was tested against structurally similar Class 1 methyltransferases, such as human phenylethanolamine-N-methyltransferase (hPNMT) and human nicotinamide-N-methyltransferase (hNNMT), indicating selectivity for INMT. The demonstration of noncompetitive mechanisms for INMT inhibition implies the presence of an inhibitory allosteric site. In silico analyses using the computer modeling software Autodock and the rabINMT sequence threaded onto the human INMT (hINMT) structure (Protein Data Bank entry 2A14 ) identified an N-terminal helix-loop-helix non-active site binding region of the enzyme. The energies for binding of DMT and PDAT to this region of rabINMT, as determined by Autodock, were -6.34 and -7.58 kcal/mol, respectively. Assessment of the allosteric control of INMT may illuminate new biochemical pathway(s) underlying the biology of INMT.

  13. Etudes on 1/N

    NASA Astrophysics Data System (ADS)

    Starinets, Andrei Olegovich

    A number of problems in string theory and lattice statistical mechanics is studied using the large N approximation, with N being the dimension of the fundamental representation of the underlying symmetry algebra. As the first problem, the absorption of a minimally coupled massless scalar in the gravitational background created by a stack of near-extremal black three-branes is considered. The low-temperature asymptotic expansion and the high-temperature perturbative expansion are obtained. A field-theoretical calculation of the absorption cross section in the brane's world-volume theory is also performed. As an application, the shear viscosity of a strongly coupled Yang-Mills plasma is computed. In the second problem, we study supergravity solutions with two asymptotically Anti de Sitter regions which are conjectured to describe the renormalization group flow of a four-dimensional field theory from a UV fixed point to an interacting IR fixed point. We show that, in the UV (IR) limit, the two-point function of a minimally-coupled scalar field depends only on the UV (IR) region of the metric, asymptotic to AdS5 thus lending a support to the conjecture. In the third problem, monotonicity and other properties of the canonical c-function in some holographic duals of 4-d quantum field theories are investigated. The canonical c-function and its derivatives are related to the 5-d Green's function of the dual supergravity theory. In the fourth problem, we study solutions of the equations (Δ - λ)φ = 0 and (Δ - λ)2φ = 0 on the covering space C AdSd of the d-dimensional Anti de-Sitter space subject to various boundary conditions, and we analyze their connection to the unitary irreducible representations of SO (d - 1, 2). Finally, as the fifth problem, we compute the phase diagram in the N --> ∞ limit for lattice RPN-1, CPN-1 and QPN-1 σ- models with the quartic action, and more generally for mixed isovector/isotensor models. We show that the N = ∞ limit exhibits

  14. H1N1 Influenza

    MedlinePlus

    ... with a fever and cough. What causes H1N1 influenza? A virus causes H1N1. It spreads from person to person. ... least 24 hours after your fever breaks. H1N1 influenza treatment Your ... H1N1. This helps kill the virus so you can recover and aren’t contagious. ...

  15. The pK(a) values of N,N,N',N'-tetrakis-(2-hydroxypropyl)ethylenediamine.

    PubMed

    McMahon, R; Brennan, M; Glennon, J D

    1986-11-01

    Aqueous solutions of the industrially important chelating agent N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine exhibit basic properties. The proton dissociation constants were determined to be 8.99 +/- 0.04 (pK(1)) and 4.30 +/- 0.04 (pK(2)) by potentiometric titration at 25 degrees in 0.15M sodium chloride.

  16. InAlN/AlN/GaN heterostructures for high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Usov, S. O.; Sakharov, A. V.; Tsatsulnikov, A. F.; Lundin, V. W.; Zavarin, E. E.; Nikolaev, A. E.; Yagovkina, M. A.; Zemlyakov, V. E.; Egorkin, V. I.; Ustinov, V. M.

    2016-08-01

    The results of development of InAlN/AlN/GaN heterostructures, grown on sapphire substrates by metal-organic chemical vapour deposition, and high electron mobility transistors (HEMTs) based on them are presented. The dependencies of the InAlN/AlN/GaN heterostructure properties on epitaxial growth conditions were investigated. The optimal indium content and InAlN barrier layer thicknesses of the heterostructures for HEMT s were determined. The possibility to improve the characteristics of HEMTs by in-situ passivation by Si3N4 thin protective layer deposited in the same epitaxial process was demonstrated. The InAlN/AlN/GaN heterostructure grown on sapphire substrate with diameter of 100 mm were obtained with sufficiently uniform distribution of sheet resistance. The HEMTs with saturation current of 1600 mA/mm and transconductance of 230 mS/mm are demonstrated.

  17. Ethyl N-phenyloxamate.

    PubMed

    García-Báez E, Efrén V; Gómez-Castro, Carlos Z; Höpfl, Herbert; Martínez-Martínez, Francisco J; Padilla-Martínez, Itzia I

    2003-10-01

    The oxamate group in the title compound, C(10)H(11)NO(3), is almost coplanar with the phenyl ring because of intramolecular hydrogen-bonding interactions, and the structure can be described as an anilide single bonded to an ethyl carboxylate group. The supramolecular structure is achieved through intermolecular hard N-H...O and soft C-H...X (X = O and phenyl) hydrogen-bonding interactions.

  18. N-body models

    NASA Technical Reports Server (NTRS)

    Miller, R. H.

    1990-01-01

    The experimental discovery of an overstability in the central regions of galaxies is briefly discussed, and numerical methods for integrating orbits are briefly addressed. The overstability manifests itself as a growing amplitude in the orbit of a galaxy's nucleus about its mass centroid. This finding may complicate studies of the topological properties of orbits and studies of the bifurcation structure of orbits. A sample problem is used to illustrate the importance of a Liouville theorem in N-body calculations.

  19. Coulomb dissociation of N,2120

    NASA Astrophysics Data System (ADS)

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

    2016-06-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

  20. Asymmetric interfacial abruptness in N-polar and Ga-polar GaN/AlN/GaN heterostructures

    SciTech Connect

    Mazumder, B.; Hurni, C. A.; Zhang, J. Y.; Speck, J. S.; Wong, M. H.; Mishra, U. K.

    2012-08-27

    In this letter, we report on the interfacial abruptness of GaN/AlN/GaN heterostructures with pulsed laser atom probe tomography (APT). The samples were grown by plasma-assisted molecular beam epitaxy (MBE) under both metal-rich and N-rich conditions on both Ga-polar (0001) GaN templates and N-polar (0001) GaN substrates. An NH{sub 3} assisted MBE technique was involved to grow similar Ga-polar and N-polar structures on GaN:Fe substrates and GaN/Al{sub 2}O{sub 3} templates, respectively, for a comparison study. We find in all cases the interface with net positive polarization charge was chemically abrupt, whereas the interface with net negative polarization charge was diffuse. We discuss the implications on device design and performance. These data validate the efficiency of APT in studying interfaces for better performance in devices.

  1. 40 CFR 721.10115 - 1-Hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-Hexadecanaminium, N,N-dibutyl-N-(2... New Uses for Specific Chemical Substances § 721.10115 1-Hexadecanaminium, N,N-dibutyl-N-(2... chemical substance identified as 1-hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1) (PMN P...

  2. 40 CFR 721.10595 - Octadecen-1-aminium, N-ethyl-N,N-dimethy-, ethyl sulfate (1:1).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Octadecen-1-aminium, N-ethyl-N,N... Significant New Uses for Specific Chemical Substances § 721.10595 Octadecen-1-aminium, N-ethyl-N,N-dimethy... chemical substance identified as octadecen-1-aminium, N-ethyl-N,N-dimethy-, ethyl sulfate (1:1) (PMN P-11...

  3. 40 CFR 721.10115 - 1-Hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 1-Hexadecanaminium, N,N-dibutyl-N-(2... New Uses for Specific Chemical Substances § 721.10115 1-Hexadecanaminium, N,N-dibutyl-N-(2... chemical substance identified as 1-hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1) (PMN P...

  4. 40 CFR 721.10115 - 1-Hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-Hexadecanaminium, N,N-dibutyl-N-(2... New Uses for Specific Chemical Substances § 721.10115 1-Hexadecanaminium, N,N-dibutyl-N-(2... chemical substance identified as 1-hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1) (PMN P...

  5. 40 CFR 721.10115 - 1-Hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 1-Hexadecanaminium, N,N-dibutyl-N-(2... New Uses for Specific Chemical Substances § 721.10115 1-Hexadecanaminium, N,N-dibutyl-N-(2... chemical substance identified as 1-hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1) (PMN...

  6. 40 CFR 721.10115 - 1-Hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Hexadecanaminium, N,N-dibutyl-N-(2... New Uses for Specific Chemical Substances § 721.10115 1-Hexadecanaminium, N,N-dibutyl-N-(2... chemical substance identified as 1-hexadecanaminium, N,N-dibutyl-N-(2-hydroxyethyl)-, bromide (1:1) (PMN P...

  7. Heats of Formation for CF(sub n) (n = 1 - 4), CF(sup +, sub n) (n = 1 - 4), and CF(sup -, sub n) (n = 1 - 3)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Arnold, James (Technical Monitor)

    1998-01-01

    Accurate heats of formation are computed for CF(sub n) (n = 1 - 4), CF(sup +, sub n) (n = 1 - 4), and CF(sup -, sub n) (n = 1 - 3). The geometries and vibrational frequencies are determined at the B3LYP level of theory. The energetics are determined at the CCSD(T) level of theory. Basis set limit values are obtained by extrapolation. In those cases where the CCSD(T) calculations become prohibitively large, the basis set extrapolation is performed at the MP2 level. The temperature dependence of the heat of formation, heat capacity, and entropy are computed for the temperature range 300 to 4000 K and fit to a polynomial.

  8. Heats of Formation for CF(sub n) (n = 1 - 4), CF(sup +, sub n) (n = 1 - 4), and CF(sup -, sub n) (n = 1 - 3)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Arnold, James (Technical Monitor)

    1998-01-01

    Accurate heats of formation are computed for CF(sub n) (n = 1 - 4), CF(sup +, sub n) (n = 1 - 4), and CF(sup -, sub n) (n = 1 - 3). The geometries and vibrational frequencies are determined at the B3LYP level of theory. The energetics are determined at the CCSD(T) level of theory. Basis set limit values are obtained by extrapolation. In those cases where the CCSD(T) calculations become prohibitively large, the basis set extrapolation is performed at the MP2 level. The temperature dependence of the heat of formation, heat capacity, and entropy are computed for the temperature range 300 to 4000 K and fit to a polynomial.

  9. Noncompetitive Inhibition of Indolethylamine-N-methyltransferase by N,N-Dimethyltryptamine and N,N-Dimethylaminopropyltryptamine

    PubMed Central

    2015-01-01

    Indolethylamine-N-methyltransferase (INMT) is a Class 1 transmethylation enzyme known for its production of N,N-dimethyltryptamine (DMT), a hallucinogen with affinity for various serotonergic, adrenergic, histaminergic, dopaminergic, and sigma-1 receptors. DMT is produced via the action of INMT on the endogenous substrates tryptamine and S-adenosyl-l-methionine (SAM). The biological, biochemical, and selective small molecule regulation of INMT enzyme activity remain largely unknown. Kinetic mechanisms for inhibition of rabbit lung INMT (rabINMT) by the product, DMT, and by a new novel tryptamine derivative were determined. After Michaelis–Menten and Lineweaver–Burk analyses had been applied to study inhibition, DMT was found to be a mixed competitive and noncompetitive inhibitor when measured against tryptamine. The novel tryptamine derivative, N-[2-(1H-indol-3-yl)ethyl]-N′,N′-dimethylpropane-1,3-diamine (propyl dimethyl amino tryptamine or PDAT), was shown to inhibit rabINMT by a pure noncompetitive mechanism when measured against tryptamine with a Ki of 84 μM. No inhibition by PDAT was observed at 2 mM when it was tested against structurally similar Class 1 methyltransferases, such as human phenylethanolamine-N-methyltransferase (hPNMT) and human nicotinamide-N-methyltransferase (hNNMT), indicating selectivity for INMT. The demonstration of noncompetitive mechanisms for INMT inhibition implies the presence of an inhibitory allosteric site. In silico analyses using the computer modeling software Autodock and the rabINMT sequence threaded onto the human INMT (hINMT) structure (Protein Data Bank entry 2A14) identified an N-terminal helix–loop–helix non-active site binding region of the enzyme. The energies for binding of DMT and PDAT to this region of rabINMT, as determined by Autodock, were −6.34 and −7.58 kcal/mol, respectively. Assessment of the allosteric control of INMT may illuminate new biochemical pathway(s) underlying the biology of INMT

  10. Viscosity of binary mixtures. II. n-butyl, n-hexyl, n-octyl, n-decyl, and n-dodecylamine with benzene and n-hexyl, n-decyl, and n-dodecylamine with cyclohexane

    NASA Astrophysics Data System (ADS)

    Oswal, S. L.; Patel, A. T.

    1992-07-01

    Viscosities of eight binary systems of n-butylamine, n-hexylamine, n-octylamine, n-decylamine, and n-dodecylamine with benzene and n-hexylamine, n-decylamine, and n-dodecylamine with cyclohexane have been measured at 303.15 K with an Ubbelohde suspended level viscometer. Based on Eyring's theory, values of excess Gibbs energy of activation ΔG *E of viscous flow have been calculated. Deviations of viscosities from linear dependence on the mole fraction and values of ΔG *E are attributed to H-bonding and to the size of alkylamine molecules. The free volume theory of Prigogine-Flory-Patterson in combination with the work of Bloomfield-Dewan has been used to estimate the excess viscosity Δ In η and the terms corresponding to enthalpy, entropy, and free volume contributions for 10 binary mixtures containing n-butyl, n-hexyl, n-octyl, n-decyl, and n-dodecylamine with benzene and cyclohexane.

  11. Exchange interactions and Curie temperatures of the tetrametal nitrides Cr₄N, Mn₄N, Fe₄N, Co₄N, and Ni₄N.

    PubMed

    Meinert, Markus

    2016-02-10

    The exchange interactions of Cr4N, Mn4N, Fe4N, Co4N, and Ni4N compounds with perovskite structure were calculated to obtain the Curie temperatures for these compounds from Monte Carlo calculations. Contrary to naíve expectation, the exchange interactions vary markedly among these five compounds. In Fe4N, the intra-sublattice interaction of the Fe 3c atoms is strongly negative, leading to a significant reduction of the Curie temperature. The calculated Curie temperatures are 291 K (Cr4N), 710 K (Mn4N), 668 K (Fe4N), 827 K (Co4N), and 121 K (Ni4N), in good agreement with experimental observations where available. The much lower Curie temperature of Ni4N compared to fcc Ni is explained on the basis of the exchange interactions.

  12. 14N15N detectability in Pluto’s atmosphere

    NASA Astrophysics Data System (ADS)

    Jessup, Kandis Lea; Gladstone, G. R.; Heays, A. N.; Gibson, S. T.; Lewis, B. R.; Stark, G.

    2013-11-01

    Based on the vapor pressure behavior of Pluto’s surface ices, Pluto’s atmosphere is expected to be predominantly composed of N2 gas. Measurement of the N2 isotopologue 15N/14N ratio within Pluto’s atmosphere would provide important clues to the evolution of Pluto’s atmosphere from the time of formation to its present state. The most straightforward way of determining the N2 isotopologue 15N/14N ratio in Pluto’s atmosphere is via spectroscopic observation of the 14N15N gas species. Recent calculations of the 80-100 nm absorption behavior of the 14N2 and 14N15N isotopologues by Heays et al. (Heays, A.N. et al. [2011]. J. Chem. Phys. 135, 244301), Lewis et al. (Lewis, B.R., Heays, A.N., Gibson, S.T., Lefebvre-Brion, H., Lefebvre, R. [2008]. J. Chem. Phys. 129, 164306); Lewis et al. (Lewis, B.R., Gibson, S.T., Zhang, W., Lefebvre-Brion, H., Robbe, J.-M. [2005]. J. Chem. Phys. 122, 144302), and Haverd et al. (Haverd, V.E., Lewis, B.R., Gibson, S.T., Stark, G. [2005]. J. Chem. Phys. 123, 214304) show that the peak magnitudes of the 14N2 and 14N15N absorption bandhead cross-sections are similar, but the locations of the bandhead peaks are offset in wavelength by ∼0.05-0.1 nm. These offsets make the segregation of the 14N2 and 14N15N absorption signatures possible. We use the most recent N2 isotopologue absorption cross-section calculations and the atmospheric density profiles resulting from photochemical models developed by Krasnopolsky and Cruickshank (Krasnopolsky, V.A., Cruickshank, D.P. [1999]. J. Geophys. Res. 104, 21979-21996) to predict the level of solar light that will be transmitted through Pluto’s atmosphere as a function of altitude during a Pluto solar occultation. We characterize the detectability of the isotopic absorption signature per altitude assuming 14N15N concentrations ranging from 0.1% to 2% of the 14N2 density and instrumental spectral resolutions ranging from 0.01 to 0.3 nm. Our simulations indicate that optical depth of unity is

  13. Improved AlGaN/GaN high electron mobility transistor using AlN interlayers

    NASA Astrophysics Data System (ADS)

    Jiménez, A.; Bougrioua, Z.; Tirado, J. M.; Braña, A. F.; Calleja, E.; Muñoz, E.; Moerman, I.

    2003-06-01

    This work reports on the effects of AlN interlayers embedded into the GaN semi-insulating buffer of AlGaN/GaN high electron mobility transistors, in comparison with standard heterostructures without AlN interlayers. Detailed optical and structural characterization data are presented, along with computer simulation results. The AlN interlayers generate a compressive strain in the GaN topmost layer, which slightly reduces the total polarization field, but most important, it prevents the AlGaN barrier from plastic relaxation. The final result is an enhanced polarization field with respect to standard heterostructures, providing an increased channel carrier density and pinch-off voltage. Electrical characterization confirms the advantages of using AlN interlayers, reaching maximum drain current density and extrinsic transconductance as high as 1.4 A/mm and 266 mS/mm, respectively, for 0.2-μm gate length.

  14. A complex containing three different kinds of Ru-N bonds: ethoxydinitronitrosyl(N,N,N',N'-tetramethylethylenediamine-kappa2N,N')ruthenium(II).

    PubMed

    Albores, Pablo; Chaia, Zulema D; Baraldo, Luis; Castellano, Eduardo E; Piro, Oscar E

    2002-04-01

    The octahedral title compound, [Ru(C(2)H(5)O)(NO)(NO(2))(2)(C(6)H(16)N(2))], crystallizes in the rhombohedral space group P3(1) with an ethoxy ligand axially coordinated trans to the nitrosyl ligand. The RuII ion is equatorially coordinated by a tetramethylethylenediamine group acting as a bidentate ligand, and to two nitro moieties whose planes are tilted with respect to the mean equatorial plane. Each nitrogen ligand bonded to the metallic centre has a different hybridization state.

  15. Magnetometory of AlGaN/GaN heterostructure wafers

    NASA Astrophysics Data System (ADS)

    Tsubaki, K.; Maeda, N.; Saitoh, T.; Kobayashi, N.

    2005-06-01

    AlGaN/GaN heterostructure wafers are becoming a key technology for next generation cellar-phone telecommunication system because of their potential for high-performance microwave applications. Therefore, the electronic properties of a 2DEG in AlGaN/GaN heterostructures have recently been discussed. In this paper, we performed the extraordinary Hall effect measurement and the SQUID magnetometory of AlGaN/GaN heterostructure wafer at low temperature. The AlGaN/GaN heterostructures were grown by low-pressure metal-organic chemical vapour phase epitaxy on (0001) SiC substrate using AlN buffers. The electron mobility and electron concentration at 4.2 K are 9,540cm2/V s and 6.6 × 1012cm-2, respectively. In the extraordinary Hall effect measurement of AlGaN/GaN heterostructures, the hysteresis of Hall resistance appeared below 4.5 K and disappeared above 4.5 K. On the other hand, the hysteresis of magnetometric data obtained by SQUID magnetometory appears near zero magnetic field when the temperature is lower than 4.5 K. At the temperature larger than 4.5 K, the hysteresis of magnetometric data disappears. And the slopes of magnetometric data with respect to magnetic field become lower as obeying Currie-Weiss law and the Curie temperature TC is 4.5 K. Agreement of TC measured by the extraordinary Hall effect and the SQUID magnetometory implies the ferromagnetism at the AlGaN/GaN heterojunction. However, the conformation of the ferromagnetism of AlGaN/GaN heterostructure is still difficult and the detailed physical mechanism is still unclear.

  16. Quantitation of N,N,N',N'-tetrakis (2-hydroxypropyl)-ethylenediamine in plasma by gas chromatography.

    PubMed

    Dunphy, M J; Smith, D J

    1989-03-24

    A wide-bore capillary gas chromatographic method with nitrogen-selective thermionic detection is described for the quantitative analysis of N,N,N',N'-tetrakis (2-hydroxypropyl)ethylenediamine (Quadrol) in plasma. N,N,N',N'-tetrakis (2-hydroxybutyl)ethylenediamine is used as an internal standard. Rat or human plasma samples (0.5 ml) are mixed with internal standard, adjusted to alkaline pH and subjected to a single extraction with dichloromethane. Quadrol recovery from plasma typically exceeds 90%. The method is linear over the range 1.0-50 micrograms/ml. The working detection limit is 0.5 microgram/ml and the analysis time is under 7 min. The procedure has been used to obtain plasma concentration versus time data for the evaluation of Quadrol pharmacokinetics in rats.

  17. N44C nebula

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Resembling the hair in Botticelli's famous portrait of the birth of Venus, an image from NASA's Hubble Space Telescope has captured softly glowing filaments streaming from hot young stars in a nearby nebula.

    The image, presented by the Hubble Heritage Project, was taken in 1996 by Hubble's Wide Field and Planetary Camera 2, designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The image is available online at

    http://heritage.stsci.edu , http://oposite.stsci.edu/pubinfo/pr/2002/12 orhttp://www.jpl.nasa.gov/images/wfpc .

    On the top right of the image is a source of its artistic likeness, a network of nebulous filaments surrounding the Wolf-Rayet star. This type of rare star is characterized by an exceptionally vigorous 'wind' of charged particles. The shock of the wind colliding with the surrounding gas causes the gas to glow.

    The Wolf-Rayet star is part of N44C, a nebula of glowing hydrogen gas surrounding young stars in the Large Magellanic Cloud. Visible from the Southern Hemisphere, the Large Magellanic Cloud is a small companion galaxy to the Milky Way.

    What makes N44C peculiar is the temperature of the star that illuminates it. The most massive stars -- those that are 10 to 50 times more massive than the Sun -- have maximum temperatures of 30,000 to 50,000 degrees Celsius (54,000 to 90,000 degrees Fahrenheit). The temperature of this star is about 75,000 degrees Celsius (135,000 degrees Fahrenheit). This unusually high temperature may be due to a neutron star or black hole that occasionally produces X-rays but is now inactive.

    N44C is part of a larger complex that includes young, hot, massive stars, nebulae, and a 'superbubble' blown out by multiple supernova explosions. Part of the superbubble is seen in red at the very bottom left of the Hubble image.

    The Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract with the Goddard

  18. Azobenzene Pd(II) complexes with N^N- and N^O-type ligands

    NASA Astrophysics Data System (ADS)

    Nikolaeva, M. V.; Puzyk, An. M.; Puzyk, M. V.

    2017-05-01

    Methods of synthesis of cyclometalated azobenzene palladium(II) complexes of [Pd(N^N)Azb]ClO4 and [Pd(N^O)Azb]ClO4 types (where Azb- is the deprotonated form of azobenzene; N^N is 2NH3, ethylenediamine, or 2,2'-bipyridine; and (N^O)- is the deprotonated form of amino acid (glycine, α-alanine, β-alanine, tyrosine, or tryptophan)) are developed. The electronic absorption and the electrochemical properties of these complexes are studied.

  19. Impact ionization in N-polar AlGaN/GaN high electron mobility transistors

    SciTech Connect

    Killat, N. E-mail: Martin.Kuball@bristol.ac.uk; Uren, M. J.; Kuball, M. E-mail: Martin.Kuball@bristol.ac.uk; Keller, S.; Kolluri, S.; Mishra, U. K.

    2014-08-11

    The existence of impact ionization as one of the open questions for GaN device reliability was studied in N-polar AlGaN/GaN high electron mobility transistors. Electroluminescence (EL) imaging and spectroscopy from underneath the device gate contact revealed the presence of hot electrons in excess of the GaN bandgap energy even at moderate on-state bias conditions, enabling impact ionization with hole currents up to several hundreds of pA/mm. The detection of high energy luminescence from hot electrons demonstrates that EL analysis is a highly sensitive tool to study degradation mechanisms in GaN devices.

  20. Synthesis of [n]- and [n.n]cyclophanes by using Suzuki-Miyaura coupling.

    PubMed

    Smith, Beverly B; Hill, Darron E; Cropp, T Ashton; Walsh, Rosa D; Cartrette, David; Hipps, Sherry; Shachter, Amy M; Pennington, William T; Kwochka, William R

    2002-07-26

    Reaction of the bis-9-BBN adduct of several dienes with 1,3-dibromobenzene via Suzuki coupling leads to a series of [n]metacyclophanes ranging in size from 10 to 17 atom members. In each case, two carbon-carbon bonds are formed in one reaction vessel. However, when the bis-9-BBN adduct of 1,5-hexadiene is coupled with a variety of aryl dihalides, larger [n.n]cyclophanes were formed in preference to the [n]cyclophanes. Four carbon-carbon bonds are formed in this instance. Single-crystal X-ray analyses of these [n.n]cyclophanes reveal interestingly shaped molecules with large cavities.

  1. Analogues of N-hydroxy-N'-phenylthiourea and N-hydroxy-N'-phenylurea as inhibitors of tyrosinase and melanin formation.

    PubMed

    Criton, Marc; Le Mellay-Hamon, Véronique

    2008-06-15

    A series of N-hydroxy-N'-phenylthiourea and N-hydroxy-N'-phenylurea analogues were prepared and evaluated as inhibitors of tyrosinase and melanin formation. The most active analogue 1 inhibited mushroom tyrosinase with an IC(50) of around 0.29 microM and also retained a substantial potency in cell culture by reducing pigment synthesis by 78%. Therefore, compound 1 could be considered as a promising candidate for preclinical drug development for skin hyperpigmentation application.

  2. In vitro stimulation of macrophages by quadrol [N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine].

    PubMed

    Bhide, M V; Patel, S; Rowland, E C; Smith, D J

    1985-01-01

    Mouse peritoneal macrophages, when exposed to Quadrol [N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine] in vitro, show a dose dependent enhanced spreading over a four-hour period. In vitro Quadrol induced phagocytosis of polystyrene beads was found to be time and concentration dependent. The rate and extent of the enhancement of phagocytosis was comparable to that observed for lipopolysaccharide and tuftsin.

  3. Oxycodone N-oxide.

    PubMed

    Sonar, Vijayakumar N; Parkin, Sean; Crooks, Peter A

    2012-11-01

    The title compound, (5R,9R,13S,14S,17R)-14-hydroxy-3-methoxy-17-methyl-4,5-epoxymorphinan-6-one N-oxide, C(18)H(21)NO(5), has been prepared in a diastereomerically pure form by the reaction of oxycodone with 3-chloroperbenzoic acid and subsequent crystallization of the product from chloroform. The crystal packing shows that the molecule exhibits intramolecular O-H···O [D···A = 2.482 (2) Å] hydrogen bonding. In addition, there are weak intermolecular C-H...O interactions which, along with van der Waals forces, stabilize the structure. The new chiral center at the 17-position is demonstrated to be R.

  4. Distributed bragg reflector using AIGaN/GaN

    DOEpatents

    Waldrip, Karen E.; Lee, Stephen R.; Han, Jung

    2004-08-10

    A supported distributed Bragg reflector or superlattice structure formed from a substrate, a nucleation layer deposited on the substrate, and an interlayer deposited on the nucleation layer, followed by deposition of (Al,Ga,B)N layers or multiple pairs of (Al,Ga,B)N/(Al,Ga,B)N layers, where the interlayer is a material selected from AlN, Al.sub.x Ga.sub.1-x N, and AlBN with a thickness of approximately 20 to 1000 angstroms. The interlayer functions to reduce or eliminate the initial tensile growth stress, thereby reducing cracking in the structure. Multiple interlayers utilized in an AlGaN/GaN DBR structure can eliminate cracking and produce a structure with a reflectivity value greater than 0.99.

  5. 76 FR 19701 - Glyphosate (N-

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-08

    ... AGENCY 40 CFR Part 180 Glyphosate (N-(phosphonomethyl) glycine); Pesticide Tolerances AGENCY... removed and reduces the established tolerance for residues of glyphosate and N-acetyl-glyphosate in or on... the established tolerance for residues of glyphosate and its metabolite (N- acetyl-glyphosate) in or...

  6. L134N Revisited

    NASA Astrophysics Data System (ADS)

    Pagani, L.; Pardo, J.-R.; Fich, M.; Motte, F.; Stepnik, B.

    L134N is a cold, starless cloud, very high above the galactic plane, close to us and well delineated in continuum dust emission maps. This cloud is considered to be representative of oxygen rich dark clouds (with the presence of SO, SO2, NO, ...). It is thus a good reference together with TMC-1 to test astrochemical models. Thanks to ISO, SCUBA and near IR wide field cameras, the detailed study of the dust has become possible in such cold and dark clouds. In parallel, progress in radiotelescope receiver sensitivity now allows to map weak lines on large surfaces. We have thus started a project to study both dust and a few gaseous key species (CO, CS, SO and N2H^+) to address several questions. We want to assess the quantity of dust and gas all over the cloud, study possible C18O and/or C17O depletion towards dense cores, evaluate the structure of the gas, the abundance of CS and SO to possibly estimate the chemical age of the cloud (time dependent models show that the CS/SO ratio diminishes with time) and evaluate the rare isotope abundances, especially 17O and 34S in a first step. To constrain the molecular abundances with the highest possible confidence, we have observed several transitions for each species and each isotopomer. Though we have observed far less species than Dickens et al. [CITE], we have done it on a larger area, including thus the strongest C18O peak and two other peaks, with a better signal-to-noise ratio. Most of the data are already acquired. We present here preliminary results.

  7. Applied N=1 Supergravity

    NASA Astrophysics Data System (ADS)

    Nath, Pran

    A review of recent developments in the applications of N=1 Supergravity to the construction of unified models of elementary particle interactions is given. Couplings of N=1 Supergravity with matter consisting of an arbitrary set of l handed multiplets and a gauge multiplet are discussed. General formulation of spontaneous symmetry breaking and the criteria for breaking of internal symmetry and of local supersymmetry are described. Construction of specific Supergrvity GUT models, the gauge heirarchy in GUT models and a deduction of the low energy effective potential are discussed. The phenomena of SU(2)XU(1) electro-weak gauge invariance breakdown by Supergravity in tree models and by radiative corrections using renormalization group methods are described. Model independent formulations of low energy physics which encompass tree and the renormalization group methods of breaking SU(2)XU(1), but also allow more general scenarios are discussed. The particle content of Supergravity unified theories at low energy is given which includes predictions, for a class of supergravity models, of light gauge fermins, i.e. of a charged Dirac fermion, the Wino, with a mass below the W boson mass and a neutral fermion, the Zino, below the mass of the Z boson mass. "Direct" gaugino masses arising from loops for the photino and the gluino, (which are massless at the tree level) are exhibited. Decays of the W and Z into photino. Vino, and Zino modes and their branching ratios into various channels are given. Experimental signals for the supersymmetrie decays are discussed and some prominent signatures such as decays into one and two jets with unbalanced energy and momentum are pointed out. The current status of the ρ-parameter, including supergravity GUT effects is given. Other experimental consequences of supergravity unified theories are also discussed.

  8. Carbon dioxide capture by planar (AlN)n clusters (n=3-5).

    PubMed

    Guo, Chen; Wang, Chong

    2017-09-26

    Searching for materials and technologies of efficient CO2 capture is of the utmost importance to reduce the CO2 impact on the environment. Therefore, the (AlN)n clusters (n = 3-5) are researched using density functional theoretical calculations. The results of the optimization show that the most stable structures of (AlN)n clusters all display planar configurations at B3LYP and G3B3 methods, which are consistent with the reported results. For these planar clusters, we further systematically studied their interactions with carbon dioxide molecules to understand their adsorption behavior at the B3LYP/6-311+G(d,p) level, including geometric optimization, binding energy, bond index, and electrostatic. We found that the planar structures of (AlN)n (n = 3-5) can capture 3-5 CO2 molecules. The result indicates that (AlN)n (n = 3-5) clusters binding with CO2 is an exothermic process (the capture of every CO2 molecule on (AlN)n clusters releases at least 30 kcal mol(-1) in relative free energy values). These analysis results are expected to further motivate the applications of clusters to be efficient CO2 capture materials.

  9. 40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...

  10. 40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...

  11. 40 CFR 721.10473 - 1-Propanaminium, 3-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-Propanaminium, 3-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts. 721.10473 Section 721.10473 Protection of...-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts. (a) Chemical substance and...

  12. 40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...

  13. 40 CFR 721.10473 - 1-Propanaminium, 3-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-Propanaminium, 3-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts. 721.10473 Section 721.10473 Protection of...-amino-N-(2-carboxyethyl)-N,N-dimethyl-, N-coco acyl derivs., inner salts. (a) Chemical substance and...

  14. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  15. 40 CFR 721.10174 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. 721.10174 Section 721.10174 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-peanut-oil acyl derivs., inner salts. (a) Chemical substance...

  16. 40 CFR 721.10055 - 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Propanaminium, 3-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. 721.10055 Section 721.10055 Protection of...-amino-N-(carboxymethyl)-N,N-dimethyl-, N-soya acyl derivs., inner salts. (a) Chemical substance and...

  17. Ion irradiation induced disappearance of dislocations in a nickel-based alloy

    NASA Astrophysics Data System (ADS)

    Chen, H. C.; Li, D. H.; Lui, R. D.; Huang, H. F.; Li, J. J.; Lei, G. H.; Huang, Q.; Bao, L. M.; Yan, L.; Zhou, X. T.; Zhu, Z. Y.

    2016-06-01

    Under Xe ion irradiation, the microstructural evolution of a nickel based alloy, Hastelloy N (US N10003), was studied. The intrinsic dislocations are decorated with irradiation induced interstitial loops and/or clusters. Moreover, the intrinsic dislocations density reduces as the irradiation damage increases. The disappearance of the intrinsic dislocations is ascribed to the dislocations climb to the free surface by the absorption of interstitials under the ion irradiation. Moreover, the in situ annealing experiment reveals that the small interstitial loops and/or clusters induced by the ion irradiation are stable below 600 °C.

  18. Cyclo-hexyl-methyl-ammonium N,N'-dicyclo-hexyl-N,N'-dimethyl-N''-(2,2,2-trifluoro-acet-yl)phospho-nic triamide).

    PubMed

    Yazdanbakhsh, Mohammad; Eshtiagh-Hosseini, Hossein; Sabbaghi, Fahimeh

    2008-12-10

    In the salt, C(7)H(16)N(+)·C(16)H(28)F(3)N(3)O(2)P(-), the P atom shows tetra-hedral coordination. Two ion pairs are linked by N-H⋯O hydrogen bonds across a center of inversion. The phosphoryl and carbonyl groups are staggered [O-P-N-C = 64.8 (3)°].

  19. BN, AlN, GaN, InN: Charge Neutrality Level, Surface, Interfaces, Doping

    NASA Astrophysics Data System (ADS)

    Brudnyi, V. N.

    2017-04-01

    On the basis of the charge neutrality concept, the analysis is fulfilled of the experimental data on the electron properties of the defective semiconductors after the radiation exposure, the electronic parameters of interfaces, surface work function and efficiency of doping with the impurities of high solubility in the nitrides of the group wz-III-N (BN, AlN, GaN, InN). The numerical evaluations of the charge neutrality levels in these compounds are presented.

  20. Relativistic scalar-vector models of the N-N and N-nuclear interactions

    SciTech Connect

    Green, A.E.S.

    1985-01-01

    This paper for the Proceedings of Conference an Anti-Nucleon and Nucleon-Nucleus Interactions summarizes work by the principal investigator and his collaborators on the nucleon-nucleon (N-N) and nucleon-nuclear (N-eta) interactions. It draws heavily on a paper presented at the Many Body Conference in Rome in 1972 but also includes a brief review of our phenomenological N-eta interaction studies. We first summarize our 48-49 generalized scalar-vector meson field theory model of the N-N interactions. This is followed by a brief description of our phenomenological work in the 50's on the N-eta interaction sponsored by the Atomic Energy Commission (the present DOE). This work finally led to strong velocity dependent potentials with spin orbit and isospin terms for shell and optical model applications. This is followed by a section on the Emergence of One-Boson Exchange Models describing developments in the 60's of quantitative generalized one boson exchange potentials (GOBEP) including our purely relativistic N-N analyses. Then follows a section on the application of this meson field model to the N-eta interaction, in particular to spherical closed shell nuclei. This work was sponsored by AFOSR but funding was halted with the Mansfield amendment. We conclude with a discussion of subsequent collateral work by former colleagues and by others who have converged upon scalar-vector relativistic models of N-N, antiN-N, N-eta and antiN-eta interactions and some lessons learned from this extended endeavor. 61 refs.

  1. GaN Device Processing

    SciTech Connect

    Pearton, S.J.; Ren, F.; Zolper, J.C.; Shul, R.J.

    1998-01-01

    Recent progress in the development of dry and wet etching techniques, implant doping and isolation, thermal processing, gate insulator technology and high reliability contacts is reviewed. Etch selectivities up to 10 for InN over AlN are possible in Inductively Coupled Plasmas using a Cl2/Ar chemistry, but in general selectivities for each binary nitride relative to each other are low ({lt} OR = 2) BECAUSE OF THE HIGH ION ENERGIES NEEDED TO INITIATE ETCHING. IMPROVED N-TYPE OHMIC CONTACT RESISTANCES ARE OBTAINED BY SELECTIVE AREA SI+ IMPLANTATION FOLLOWED BY VERY HIGH TEMPERATURE ({gt}1300 deg C) anneals in which the thermal budget is minimized and AlN encapsulation prevents GaN surface decomposition. Implant isolation is effective in GaN, AlGaN and AlInN, but marginal in InGaN. Candidate gate insulators for GaN include AlN, AlON and Ga(Gd)O(x), but interface state densities are still to high to realize state-of-the-art MIS devices.

  2. N abundance of nodules as an indicator of N metabolism in n(2)-fixing plants.

    PubMed

    Shearer, G; Feldman, L; Bryan, B A; Skeeters, J L; Kohl, D H; Amarger, N; Mariotti, F; Mariotti, A

    1982-08-01

    This paper expands upon previous reports of (15)N elevation in nodules (compared to other tissues) of N(2)-fixing plants. N(2)-Fixing nodules of Glycine max (soybeans), Vigna unguiculata (cowpea), Phaseolus vulgaris (common bean), Phaseolus coccineus (scarlet runner bean), Prosopis glandulosa (mesquite), and Olneya tesota (desert ironwood) were enriched in (15)N. Nodules of Vicia faba (fava beans), Arachis hypogaea (peanut), Trifolium pratense (red clover), Pisum sativum (pea), Lathyrus sativus (grass pea), Medicago sativa (alfalfa), and Lupinus mutabilis (South American lupine) were not; nor were the nodules of nine species of N(2)-fixing nonlegumes. The nitrogen of ineffective nodules of soybeans and cowpeas was not enriched in (15)N. Thus, (15)N elevation in nodules of these plants depends on active N(2)-fixation. Results obtained so far on the generality of (15)N enrichment in N(2)-fixing nodules suggest that only the nodules of plants which actively fix N(2) and which transport allantoin or allantoic acid exhibit (15)N enrichment.

  3. L134N Revisited

    NASA Astrophysics Data System (ADS)

    Pagani, L.; Pardo-Carrion, J. R.; Stepnik, B.

    2001-07-01

    L134N (also known as L183) is a very cold, starless and nearby dark cloud which has attracted much attention from the astrochemists in the past. They have been using it as an oxygen-rich reference to test their models in parallel with TMC-1, the other, but carbon-rich, reference. However, our knowledge of the cloud temperature, structure, and various species abundances has relied for a long time largely on the work by Swade (1987a, 1987b) which suffers from low signal-to-noise C18O and CS maps and limited excitation analysis. This work has been recently repeated and improved by Dickens et al. (2000) but they still lack adequate surface coverage, higher rotational lines of important species and comparison with the dust. While FIRST will probably find many new species in this cloud, it is time to revisit completely this source in order to interpret correctly the FIRST results to come. We have thus made a complete survey of several transitions of CO, 13CO, C18O, C17O, CS, C34S, SO and 34SO species with the NRAO 12-m and CSO 10-m together with maps of the dust from ISO and SCUBA to assess the fundamental properties of this cloud. Preliminary results are reported here.

  4. Capture cross sections of 15N(n, γ)16N at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Fan, Guang-Wei; Ma, Jun-Bing; Sheng, Zong-Qiang; Shi, Guo-Zhu; Tian, Feng; Wang, Jun; Zhang, Chao

    2016-12-01

    We have reanalyzed reaction cross sections of 16N on a 12C target. The nucleon density distribution of 16N, especially surface density distribution, was extracted using the modified Glauber model. On the basis of dilute surface densities, the 15N(n, γ)16N reaction is discussed within the framework of the direct capture reaction mechanism. The calculations agree quite well with the experimental data. Support given by National Natural Science Foundation of China (11447236, 11505002, 11247001) and Foundation of Anhui University of Science and Technology (11130, 12608)

  5. Terahertz Generation in GaN/AlGaN Superlattices

    DTIC Science & Technology

    2009-02-28

    Morkoc, hmorkoc@vcu.edu Organization: Title: Program manager: Virginia Commonwealth University Terahertz generation in GaN /AlGaN superlattices...Final 3. DATES COVERED (From - To) 08/01/07-11/30/08 4. TITLE AND SUBTITLE THZ-OSCILLATIONS IN GAN /ALUMINUM GAN SUPERLATTICES 5a. CONTRACT NUMBER...that we learned in structures grown on GaN substrates which we believe will give way to tunneling dominated current at resonant states. Once we

  6. Tertiary amine N-oxides as bioreductive drugs: DACA N-oxide, nitracrine N-oxide and AQ4N.

    PubMed

    Wilson, W R; Denny, W A; Pullen, S M; Thompson, K M; Li, A E; Patterson, L H; Lee, H H

    1996-07-01

    Tertiary amine N-oxides of DNA intercalators with alkylamino sidechains are a new class of bioreductive drugs. N-oxidation masks the cationic charge of the amines, forming prodrugs with low DNA binding affinity and low toxicity which can be activated selectively by metabolic reduction under hypoxic conditions. This study compares three intercalator N-oxides (NC-NO, DACA-NO and AQ4N), which, respectively, give nitracrine (NC), DACA and AQ4 on reduction. In aerobic cell culture all three N-oxide were much less toxic than the corresponding amines, and showed large increases in cytotoxicity under hypoxia. The topoisomerase poisons DACA and AQ4 (and their N-oxides) were less active against non-cycling than cycling cells. However, only AQ4N was active against the mouse mammary tumour MDAH-MCa-4. This dialkylaminoanthraquinone-di-N-oxide has activity at least as great as the reference bioreductive drug RB 6145 against this tumour, both with and without radiation and when combined with the tumour blood flow inhibitor 5,6-dimethylxanthenone-4-acetic acid (DMXAA). It is suggested that the high in vivo activity of AQ4N relative to the other topoisomerase-targeted N-oxide, DACA-NO, may be in part due to release in hypoxic cells of an intracalator with sufficiently high DNA binding affinity that it is retained long enough to kill non-cycling cells when they eventually re-enter the cell cycle.

  7. Tertiary amine N-oxides as bioreductive drugs: DACA N-oxide, nitracrine N-oxide and AQ4N.

    PubMed Central

    Wilson, W. R.; Denny, W. A.; Pullen, S. M.; Thompson, K. M.; Li, A. E.; Patterson, L. H.; Lee, H. H.

    1996-01-01

    Tertiary amine N-oxides of DNA intercalators with alkylamino sidechains are a new class of bioreductive drugs. N-oxidation masks the cationic charge of the amines, forming prodrugs with low DNA binding affinity and low toxicity which can be activated selectively by metabolic reduction under hypoxic conditions. This study compares three intercalator N-oxides (NC-NO, DACA-NO and AQ4N), which, respectively, give nitracrine (NC), DACA and AQ4 on reduction. In aerobic cell culture all three N-oxide were much less toxic than the corresponding amines, and showed large increases in cytotoxicity under hypoxia. The topoisomerase poisons DACA and AQ4 (and their N-oxides) were less active against non-cycling than cycling cells. However, only AQ4N was active against the mouse mammary tumour MDAH-MCa-4. This dialkylaminoanthraquinone-di-N-oxide has activity at least as great as the reference bioreductive drug RB 6145 against this tumour, both with and without radiation and when combined with the tumour blood flow inhibitor 5,6-dimethylxanthenone-4-acetic acid (DMXAA). It is suggested that the high in vivo activity of AQ4N relative to the other topoisomerase-targeted N-oxide, DACA-NO, may be in part due to release in hypoxic cells of an intracalator with sufficiently high DNA binding affinity that it is retained long enough to kill non-cycling cells when they eventually re-enter the cell cycle. PMID:8763844

  8. New methods for preparing n, n-dialkyltrifluoroacetamides

    NASA Technical Reports Server (NTRS)

    Hsu, L.

    1972-01-01

    The customary preparative methods for N,N-dialkyltrifluoroacetamides involve the acylation of an amine by trifluoroacetic acid or its derivatives. In this report the synthesis of N,N-dialkyltrifluoroacetamides by reacting trifluoroacetic anhydride or acid with disubstituted formamides and acetamides is discussed. These reactions are interpreted with the aid of gas chromatographic analysis. Different reaction mechanisms are proposed for the reactions of formamides and acetamides with trifluoroacetic anhydride or acid. The use of the proposed reaction mechanisms for the synthesis of other fluorinated compounds is discussed.

  9. New methods for preparing N,N-dialkyltrifluoroacetamides

    NASA Technical Reports Server (NTRS)

    Hsu, L.

    1972-01-01

    The customary preparative methods for N,N-dialkyltrifluoroacetamides involve the acylation of an amine by trifluoroacetic acid or its derivatives. The synthesis of N,N-dialkyltrifluoroacetamides by reacting trifluoroacetic anhydride or acid with disubstituted formamides and acetamides is discussed. These reactions were interpreted with the aid of gas chromatographic analysis. Different reaction mechanisms are proposed for the reactions of formamides and acetamides with trifluoroacetic anhydride or acid. The use of the proposed reaction mechanisms for the synthesis of other fluorinated compounds is discussed.

  10. Radiation hardness of n-GaN schottky diodes

    SciTech Connect

    Lebedev, A. A. Belov, S. V.; Mynbaeva, M. G.; Strel’chuk, A. M.; Bogdanova, E. V.; Makarov, Yu. N.; Usikov, A. S.; Kurin, S. Yu.; Barash, I. S.; Roenkov, A. D.; Kozlovski, V. V.

    2015-10-15

    Schottky-barrier diodes with a diameter of ∼10 µm are fabricated on n-GaN epitaxial films grown by hydride vapor-phase epitaxy (HVPE) on sapphire substrates. The changes in the parameters of the diodes under irradiation with 15 MeV protons are studied. The carrier removal rate was found to be 130–145 cm{sup –1}. The linear nature of the dependence N = f(D) (N is the carrier concentration, and D, the irradiation dose) shows that compensation of the material is associated with transitions of electrons from shallow donors to deep acceptor levels which are related to primary radiation defects.

  11. N=1 deformations and RG flows of N=2 SCFTs

    NASA Astrophysics Data System (ADS)

    Maruyoshi, Kazunobu; Song, Jaewon

    2017-02-01

    We study certain N=1 preserving deformations of four-dimensional N=2 superconformal field theories (SCFTs) with non-abelian flavor symmetry. The deformation is described by adding an N=1 chiral multiplet transforming in the adjoint representation of the flavor symmetry with a superpotential coupling, and giving a nilpotent vacuum expectation value to the chiral multiplet which breaks the flavor symmetry. This triggers a renormalization group flow to an infrared SCFT. Remarkably, we find classes of theories flow to enhanced N=2 supersymmetric fixed points in the infrared under the deformation. They include generalized Argyres-Douglas theories and rank-one SCFTs with non-abelian flavor symmetries. Most notably, we find renormalization group flows from the deformed conformal SQCDs to the ( A 1 , A n ) Argyres-Douglas theories. From these "Lagrangian descriptions," we compute the full superconformal indices of the ( A 1 , A n ) theories and find agreements with the previous results. Furthermore, we study the cases, including the T N and R 0, N theories of class S and some of rank-one SCFTs, where the deformation gives genuine N=1 fixed points.

  12. Light dilaton in the large N tricritical O (N ) model

    NASA Astrophysics Data System (ADS)

    Omid, Hamid; Semenoff, Gordon W.; Wijewardhana, L. C. R.

    2016-12-01

    The leading order of the large N limit of the O (N ) symmetric phi-six theory in three dimensions has a phase which exhibits spontaneous breaking of scale symmetry accompanied by a massless dilaton which is a Goldstone boson. At the next-to-leading order in large N , the phi-six coupling has a beta function of order 1 /N and it is expected that the dilaton acquires a small mass, proportional to the beta function and the condensate. In this article, we show that this "light dilaton" is actually a tachyon. This indicates an instability of the phase of the theory with spontaneously broken approximate scale invariance.

  13. Electrochemical fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide

    NASA Technical Reports Server (NTRS)

    Hsu, L.-C.

    1979-01-01

    The paper presents the results of experiments concerning the fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide carried out on a laboratory scale in an advanced 'Simons' type electrochemical apparatus which could be operated automatically from ambient to 50 psi pressure. It is shown that a variety of fluorine-substituted products are formed, depending upon electrolysis conditions and concentrations of reactant relative to the NaF, KF, HF electrolyte. A new reaction mechanism of electrochemical fluorination of trichloroethylene is proposed. Finally, the solvency-to-fluorine content relationship of fluorinated N, N-dimethyltrifluoroacetamide is described.

  14. Electrochemical fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide

    NASA Technical Reports Server (NTRS)

    Hsu, L. C.

    1979-01-01

    Fluorination of trichloroethylene and N, N-dimethyltrifluoroacetamide was carried out on a laboratory scale in an advanced Simons type electrochemical apparatus which could be operated automatically from ambient to 50 psi pressure. A variety of fluorine-substituted products are formed, depending upon electrolysis conditions and concentrations of reactant relative to the NaF, KF, HF electrolyte. A new reaction mechanism of electrochemical fluorination of trichloroethylene is proposed. The solvency-to-fluorine content relationship of fluorinated N, N-dimethyltrifluoroacetamide is described.

  15. Low resistance GaN/InGaN/GaN tunnel junctions

    NASA Astrophysics Data System (ADS)

    Krishnamoorthy, Sriram; Akyol, Fatih; Park, Pil Sung; Rajan, Siddharth

    2013-03-01

    Enhanced interband tunnel injection of holes into a p-n junction is demonstrated using p-GaN/InGaN/n-GaN tunnel junctions with a specific resistivity of 1.2 × 10-4 Ω cm2. The design methodology and low-temperature characteristic of these tunnel junctions are discussed, and insertion into a p-n junction device is described. Applications of tunnel junctions in III-nitride optoelectronics devices are explained using energy band diagrams. The lower bandgap and polarization fields reduce tunneling barrier, eliminating the need for ohmic contacts to p-type GaN. This demonstration of efficient tunnel injection of carriers in III-nitrides can lead to a replacement of existing resistive p-type contact material in light emitters with tunneling contact layers requiring very little metal footprint on the surface, resulting in enhanced light extraction.

  16. Reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure

    NASA Astrophysics Data System (ADS)

    Chakraborty, Apurba; Ghosh, Saptarsi; Mukhopadhyay, Partha; Jana, Sanjay K.; Dinara, Syed Mukulika; Bag, Ankush; Mahata, Mihir K.; Kumar, Rahul; Das, Subhashis; Das, Palash; Biswas, Dhrubes

    2016-03-01

    The reverse bias leakage current mechanism of AlGaN/InGaN/GaN heterostructure is investigated by current-voltage measurement in temperature range from 298 K to 423 K. The Higher electric field across the AlGaN barrier layer of AlGaN/InGaN/GaN double heterostructure due to higher polarization charge is found to be responsible for strong Fowler-Nordheim (FN) tunnelling in the electric field higher than 3.66 MV/cm. For electric field less than 3.56 MV/cm, the reverse bias leakage current is also found to follow the trap assisted Frenkel-Poole (FP) emission in low negative bias region. Analysis of reverse FP emission yielded the barrier height of trap energy level of 0.34 eV with respect to Fermi level. [Figure not available: see fulltext.

  17. RBS Depth Profiling Analysis of (Ti, Al)N/MoN and CrN/MoN Multilayers

    NASA Astrophysics Data System (ADS)

    Han, Bin; Wang, Zesong; Devi, Neena; Kondamareddy, K. K.; Wang, Zhenguo; Li, Na; Zuo, Wenbin; Fu, Dejun; Liu, Chuansheng

    2017-03-01

    (Ti, Al)N/MoN and CrN/MoN multilayered films were synthesized on Si (100) surface by multi-cathodic arc ion plating system with various bilayer periods. The elemental composition and depth profiling of the films were investigated by Rutherford backscattering spectroscopy (RBS) using 2.42 and 1.52 MeV Li2+ ion beams and different incident angles (0°, 15°, 37°, and 53°). The microstructures of (Ti, Al)N/MoN multilayered films were evaluated by X-ray diffraction. The multilayer periods and thickness of the multilayered films were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) and then compared with RBS results.

  18. Update of ENDL U(n,2n), U(n,gamma), U(n,f) Evaluations

    SciTech Connect

    Beck, B; Brown, D A; McNabb, D P

    2004-02-13

    The authors are in the re-evaluating of all the actinide cross section evaluations in LLNL's ENDL database, starting with uranium and focusing on inventory changing reactions. This article describes their first serious pass at updating the uranium cross section data, including estimates of cross section uncertainties. Furthermore, they are developing new tools to automate the re-evaluation and this article contains some preliminary results from these codes, namely the {sup 235}U(n, 2n) and {sup 238}U(n, 2n) evaluations.

  19. New N,N,N',N'-tetradentate Pyrazoly Agents: Synthesis and Evaluation of their Antifungal and Antibacterial Activities.

    PubMed

    Abrigach, Farid; Bouchal, Btissam; Riant, Olivier; Macé, Yohan; Takfaoui, Abdelilah; Radi, Smaail; Oussaid, Abdelouahad; Bellaoui, Mohammed; Touzani, Rachid

    2016-01-01

    A new library of N,N,N',N' -tetradentate pyrazoly compounds containing a pyrazole moiety was synthesized by the condensation of (3,5-dimethyl-1H-pyrazol-1-yl)methanol 2a or (1H-pyrazol-1-yl)methanol 2b with a series of primary diamines in refluxed acetonitrile for 6h. The antifungal activity against the budding yeast Saccharomyces cerevisiae, as well as the antibacterial activity against Escherichia coli of these new tetradentate ligands were studied. We found that these tetradentate ligands act specifically as antifungal agents and lack antibacterial activity. Their biological activities depend on the nature of the structure of the compounds.

  20. Nonlinear N=2 global supersymmetry

    NASA Astrophysics Data System (ADS)

    Antoniadis, Ignatios; Derendinger, Jean-Pierre; Markou, Chrysoula

    2017-06-01

    We study the partial breaking of N=2 global supersymmetry, using a novel formalism that allows for the off-shell nonlinear realization of the broken supersymmetry, extending previous results scattered in the literature. We focus on the Goldstone degrees of freedom of a massive N=1 gravitino multiplet which are described by deformed N=2 vector and single-tensor superfields satisfying nilpotent constraints. We derive the corresponding actions and study the interactions of the superfields involved, as well as constraints describing incomplete N=2 matter multiplets of non-linear supersymmetry (vectors and single-tensors).

  1. Advanced heat exchanger development for molten salts

    DOE PAGES

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; ...

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet materialmore » in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.« less

  2. Advanced heat exchanger development for molten salts

    SciTech Connect

    Sabharwall, Piyush; Clark, Denis; Glazoff, Michael; Zheng, Guiqiu; Sridharan, Kumar; Anderson, Mark

    2014-12-01

    This study addresses present work concerned with advanced heat exchanger development for molten salt in nuclear and non nuclear thermal systems. The molten salt systems discussed herein use alloys, such as Hastelloy N and 242, which show corrosion resistance to molten salt at nominal operating temperatures up to 700°C. These alloys were diffusion welded, and the corresponding information is presented. Test specimens were prepared for exposing diffusion welds to molten salt environments. Hastelloy N and 242 were found to be weldable by diffusion welding, with ultimate tensile strengths about 90% of base metal values. Both diffusion welds and sheet material in Hastelloy N were corrosion tested in?58 mol% KF and 42 mol% ZrF4 at 650, 700, and 850°C for 200, 500, and 1,000 hours. Corrosion rates found were similar between welded and nonwelded materials, typically <10 mils per year. For materials of construction, nickel and alloys with dense nickel coatings are effectively inert to corrosion in fluorides, but not so in chlorides. Hence, additional testing of selected alloys for resistance to intergranular corrosion is needed, as is a determination of corrosion rate as a function of contaminant type and alloy composition with respect to chromium and carbon to better define the optimal chromium and carbon composition, independent of galvanic or differential solubility effects. Also presented is the division of the nuclear reactor and high temperature components per ASME standards, along with design requirements for a subcritical Rankine power cycle heat exchanger that has to overcome pressure difference of about 17 MPa.

  3. Confinement at large-N. [N = number of colors

    SciTech Connect

    Klinkhamer, F.R.

    1985-06-01

    Recent numerical results indicate that QCD in the limit of an infinite number (N) of colors also has confinement and moreover that it looks rather similar to normal QCD with N = 3 colors. This imposes severe restrictions on what the mechanism of confinement can be.

  4. 4,4\\'-Methylene bis(N,N\\'-dimethyl)aniline

    Integrated Risk Information System (IRIS)

    4,4 ' - Methylene bis ( N , N ' - dimethyl ) aniline ; CASRN 101 - 61 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Haz

  5. Optical characterization of AlN/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Ursaki, V. V.; Tiginyanu, I. M.; Zalamai, V. V.; Hubbard, S. M.; Pavlidis, D.

    2003-10-01

    AlN/GaN/sapphire heterostructures with AlN gate film thickness of 3-35 nm are characterized using photoreflectivity (PR) and photoluminescence (PL) spectroscopy. Under a critical AlN film thickness, the luminescence from the GaN channel layer near the interface proves to be excitonic. No luminescence related to the recombination of the two-dimensional electron gas (2DEG) is observed, in spite of high 2DEG parameters indicated by Hall-effect measurements. The increase of the AlN gate film thickness beyond a critical value leads to a sharp decrease in exciton resonance in PR and PL spectra as well as to the emergence of a PL band in the 3.40-3.45 eV spectral range. These findings are explained taking into account the formation of defects in the GaN channel layer as a result of strain-induced AlN film cracking. A model of electronic transitions responsible for the emission band involved is proposed.

  6. Radiative n 14N capture at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.

    2013-06-01

    In the potential cluster model with forbidden states and classification of orbital cluster states according to Young's schemes, the possibility is considered of describing the experimental data for the total cross sections of radiative n 14N capture at energies from 25.0 meV (25•10-3 eV) to 1.0 MeV. It is shown that on the whole it is possible to successfully explain the behavior of these cross sections outside the resonant energy region on the basis of the E1 transition from the 2S1/2 scattering wave with zero phase to the bound 2Р1/2 state of the 15N nucleus in the n14N channel.

  7. Delta15N of soil N and plants in a N-saturated, subtropical forest of southern China.

    PubMed

    Koba, K; Isobe, K; Takebayashi, Y; Fang, Y T; Sasaki, Y; Saito, W; Yoh, M; Mo, J; Liu, L; Lu, X; Zhang, T; Zhang, W; Senoo, K

    2010-09-15

    We investigated the delta(15)N profile of N (extractable NH(4)(+), NO(3)(-), and organic N (EON)) in the soil of a N-saturated subtropical forest. The order of delta(15)N in the soil was EON > NH(4)(+) > NO(3)(-). Although the delta(15)N of EON had been expected to be similar to that of bulk soil N, it was higher than that of bulk soil N by 5 per thousand. The difference in delta(15)N between bulk soil N and EON (Delta(15)N(bulk-EON)) was correlated significantly with the soil C/N ratio. This correlation implies that carbon availability, which determines the balance between N assimilation and dissimilation of soil microbes, is responsible for the high delta(15)N of EON, as in the case of soil microbial biomass delta(15)N. A thorough delta(15)N survey of available N (NH(4)(+), NO(3)(-), and EON) in the soil profiles from the organic layer to 100 cm depth revealed that the delta(15)N of the available N forms did not fully overlap with the delta(15)N of plants. This mismatch in delta(15)N between that of available N and that of plants reflects apparent isotopic fractionation during N uptake by plants, emphasizing the high N availability in this N-saturated forest. Copyright 2010 John Wiley & Sons, Ltd.

  8. Theoretical study of the Si(5-n)(BH)n2- and Na(Si(5-n)(BH)n)- (n = 0-5) systems.

    PubMed

    Osorio, Edison; Sergeeva, Alina P; Santos, Juan Carlos; Tiznado, William

    2012-12-21

    The potential energy surfaces of the Na(Si(5-n)(BH)(n))(-) and Si(5-n)(BH)(n)(2-) (n = 0-5) systems have been explored in detail. We established that all the global minimum structures of anionic and dianionic systems can be obtained by substitution of one or more silicon atoms of the global minima of NaSi(5)(-) and Si(5)(2-) for B-H units. The conservation of the overall structure upon isoelectronic substitution was shown to be due to the preservation of the chemical bonding pattern. Theoretical VDEs were calculated for all of the sodiated Na(Si(5-n)(BH)(n))(-) (n = 0-5) systems to facilitate their experimental detection.

  9. Whence so much N-15

    NASA Astrophysics Data System (ADS)

    Kerridge, J. F.

    1982-02-01

    Models for mechanisms which cause the widely varying N-15/N-14 stable isotope ratios observed in meteoritic and lunar samples are discussed. Interstellar ionization has been observed to be insufficient to account for the fractionations seen in the samples, which vary by as much as 5% from what is judged to be remnants of protosolar nebular material. An upper limit of less than -21% is suggested for the protosolar ratio, which implies a production of N-15 in surface regions of the sun, although gamma ray flux measurements of the sun indicate that the levels of nuclear activity are too low to form satisfactory quantities of N-15. The addition of N-15 by alien matter is not supportable due to the paucity of N-15 in the interstellar medium. Spacecraft measurements have also cast doubt on an influx due to solar wind ejection, and it is noted that the Galileo mission to Jupiter may resolve the estimates of the protosolar N-15/N-14 ratio because no net fractionation would have occurred during accretion by Jupiter, thereby leaving all Jovian nitrogen bound up in NH3.

  10. [Ir(N^N^N)(C^N)L]+: a new family of luminophores combining tunability and enhanced photostability.

    PubMed

    Chirdon, Danielle N; Transue, Wesley J; Kagalwala, Husain N; Kaur, Aman; Maurer, Andrew B; Pintauer, Tomislav; Bernhard, Stefan

    2014-02-03

    The relatively unexplored luminophore architecture [Ir(N^N^N)(C^N)L](+) (N^N^N = tridentate polypyridyl ligand, C^N = 2-phenylpyridine derivative, and L = monodentate anionic ligand) offers the stability of tridentate polypyridyl coordination along with the tunability of three independently variable ligands. Here, a new family of these luminophores has been prepared based on the previously reported compound [Ir(tpy)(ppy)Cl](+) (tpy = 2,2':6',2″-terpyridine and ppy = 2-phenylpyridine). Complexes are obtained as single stereoisomers, and ligand geometry is unambiguously assigned via X-ray crystallography. Electrochemical analysis of the materials reveals facile HOMO modulation through ppy functionalization and alteration of the monodentate ligand's field strength. Emission reflects similar modulation shifting from orange to greenish-blue upon replacement of chloride with cyanide. Many of the new compounds exhibit impressive room temperature phosphorescence with lifetimes near 3 μs and quantum yields reaching 28.6%. Application of the new luminophores as photosensitizers for photocatalytic hydrogen generation reveals that their photostability in coordinating solvent is enhanced as compared to popular [Ir(ppy)2(bpy)](+) (bpy = 2,2'-bipyridine) photosensitizers. Yet, the binding of their monodentate ligand emerges as a source of instability during the redox processes of cyclic voltammetry and mass spectrometry. DFT modeling of electronic structure is provided for all compounds to elucidate experimental properties.

  11. Analysis of InGaN light-emitting diodes with GaN-AlGaN and AlGaN-GaN composition-graded barriers

    SciTech Connect

    Yang, Yujue; Wang, Junxi; Li, Jinmin; Zeng, Yiping

    2014-06-21

    The effects of InGaN-based light-emitting diodes (LEDs) with Al composition increasing and decreasing GaN-AlGaN barriers along the growth direction are studied numerically. Simulation results suggest that the LEDs with GaN-AlGaN composition-decreased barriers show more significant enhancement of light-output power and internal quantum efficiency than LEDs with composition-increasing GaN-AlGaN barriers when compared with the conventional LED with GaN barriers, due to the improvement in hole injection efficiency and electron blocking capability. Moreover, the optical performance is further improved by replacing GaN-AlGaN barriers with AlGaN-GaN barriers of the same Al composition-decreasing range, which are mainly attributed to the modified band diagrams. In addition, the major causes of the different efficiency droop behaviors for all the designed structures are explained by the electron leakage current and the different increase rates of hole concentration with injection current.

  12. Crack Growth Rate Modeling of a Titanium-Aluminide Alloy Under Thermal-Mechanical Cycling

    DTIC Science & Technology

    1991-12-01

    induced creep or environmental degradation [36]. This damage can occur on or below the surface of a material. One of the best examples of this is...Hastelloy-X, and B-1900 + hafnium . They were successful in predicting TMF crack growth rates to within a factor of five with all the parameters except...superalloys: MAR-M 509, B-1900 + hafnium (Hf), and MAR-M200 + Hf. They concludpd that at low growth rates, da/dN depends only on AK, . Out-of-phase TMF

  13. Electrochemical Impedance Spectroscopy Of Metal Alloys

    NASA Technical Reports Server (NTRS)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  14. Method for homogenizing alloys susceptible to the formation of carbide stringers and alloys prepared thereby

    DOEpatents

    Braski, David N.; Leitnaker, James M.

    1980-01-01

    A novel fabrication procedure prevents or eliminates the reprecipitation of segregated metal carbides such as stringers in Ti-modified Hastelloy N and stainless steels to provide a novel alloy having carbides uniformly dispersed throughout the matrix. The fabrication procedure is applicable to other alloys prone to the formation of carbide stringers. The process comprises first annealing the alloy at a temperature above the single phase temperature for sufficient time to completely dissolve carbides and then annealing the single phase alloy for an additional time to prevent the formation of carbide stringers upon subsequent aging or thermomechanical treatment.

  15. 4-Bromo-N-(di-n-propyl-carbamothioyl)-benzamide.

    PubMed

    Binzet, Gün; Flörke, Ulrich; Külcü, Nevzat; Arslan, Hakan

    2009-02-04

    The synthesis of the title compound, C(14)H(19)BrN(2)OS, involves the reaction of 4-bromo-benzoyl chloride with potassium thio-cyanate in acetone followed by condensation of the resulting 4-bromo-benzoyl isothio-cyanate with di-n-propyl-amine. Typical thio-urea carbonyl and thio-carbonyl double bonds, as well as shortened C-N bonds, are observed in the title compound. The short C-N bond lengths in the centre of the mol-ecule reveal the effects of resonance in this part of the mol-ecule. The asymmetric unit of the title compound contains two crystallographically independent mol-ecules, A and B. There is very little difference between the bond lengths and angles of these mol-ecules. In mol-ecule B, one di-n-propyl group is twisted in a -anti-periplanar conformation with C-C-C-H = -179.1 (3)° and the other adopts a -synclinal conformation with C-C-C-H = -56.7 (4)°; in mol-ecule A the two di-n-propyl groups are twisted in + and -anti-periplanar conformations, with C-C-C-H = -179.9 (3) and 178.2 (3)°, respectively. In the crystal, the mol-ecules are linked into dimeric pairs via pairs of N-H⋯S hydrogen bonds.

  16. Configuration space Faddeev formalism: Λ + n + n bound state search

    NASA Astrophysics Data System (ADS)

    Suslov, Vladimir; Filikhin, Igor; Vlahovic, Branislav

    2015-04-01

    The HypHI Collaboration has recently reported the evidence for bound state of Λ + n + n system (Phys. Rev. C 88, 041001(R) (2013)). However, the theoretical analysis did not find Λ3n bound state (see, for instance, Phys. Lett. B 736, 93 (2014)). In the present work we will describe our attempt to construct a phenomenological three-body ΛNN force with the spin-isospin dependence that is attractive in the channel T=1, S=1/2. This dependence was tested to reproduce the value of ground state energy for Λ3H hypernuclei. The formalism of the configuration-space Faddeev equations is applied for Λ + n + n and Λ + n + p systems. As Λ + n interaction the s-wave potential simulating model NSC97f is used. This potential reproduces well the hyperon binding energy for Λ3H nuclei (J. Phys. G: 31, 389 (2005)). The details of the model and obtained results will be presented. This work is supported by the NSF (HRD-1345219) and NASA (NNX09AV07A).

  17. Genuine N -partite entanglement without N -partite correlation functions

    NASA Astrophysics Data System (ADS)

    Tran, Minh Cong; Zuppardo, Margherita; de Rosier, Anna; Knips, Lukas; Laskowski, Wiesław; Paterek, Tomasz; Weinfurter, Harald

    2017-06-01

    A genuinely N -partite entangled state may display vanishing N -partite correlations measured for arbitrary local observables. In such states the genuine entanglement is noticeable solely in correlations between subsets of particles. A straightforward way to obtain such states for odd N is to design an "antistate" in which all correlations between an odd number of observers are exactly opposite. Evenly mixing a state with its antistate then produces a mixed state with no N -partite correlations, with many of them genuinely multiparty entangled. Intriguingly, all known examples of "entanglement without correlations" involve an odd number of particles. Here we further develop the idea of antistates, thereby shedding light on the different properties of even and odd particle systems. We conjecture that there is no antistate to any pure even-N -party entangled state making the simple construction scheme unfeasible. However, as we prove by construction, higher-rank examples of entanglement without correlations for arbitrary even N indeed exist. These classes of states exhibit genuine entanglement and even violate an N -partite Bell inequality, clearly demonstrating the nonclassical features of these states as well as showing their applicability for quantum information processing.

  18. O( N) Random Tensor Models

    NASA Astrophysics Data System (ADS)

    Carrozza, Sylvain; Tanasa, Adrian

    2016-11-01

    We define in this paper a class of three-index tensor models, endowed with {O(N)^{⊗ 3}} invariance ( N being the size of the tensor). This allows to generate, via the usual QFT perturbative expansion, a class of Feynman tensor graphs which is strictly larger than the class of Feynman graphs of both the multi-orientable model (and hence of the colored model) and the U( N) invariant models. We first exhibit the existence of a large N expansion for such a model with general interactions. We then focus on the quartic model and we identify the leading and next-to-leading order (NLO) graphs of the large N expansion. Finally, we prove the existence of a critical regime and we compute the critical exponents, both at leading order and at NLO. This is achieved through the use of various analytic combinatorics techniques.

  19. Atom probe analysis of AlN interlayers in AlGaN/AlN/GaN heterostructures

    SciTech Connect

    Mazumder, Baishakhi; Kaun, Stephen W.; Speck, James S.; Lu, Jing; Keller, Stacia; Mishra, Umesh K.

    2013-03-18

    Atom probe tomography was used to characterize AlN interlayers in AlGaN/AlN/GaN heterostructures grown by plasma-assisted molecular beam epitaxy (PAMBE), NH{sub 3}-based molecular beam epitaxy (NH{sub 3}-MBE), and metal-organic chemical vapor deposition (MOCVD). The PAMBE-grown AlN interlayer had the highest purity, with nearly 100% of group-III sites occupied by Al. The group-III site concentrations of Al for interlayers grown by NH{sub 3}-MBE and MOCVD were {approx}85% and {approx}47%, respectively. Hall measurements were performed to determine the two-dimensional electron gas mobility and sheet concentration. Sheet concentrations were {approx}25%-45% higher with molecular beam epitaxy than with MOCVD, and these results matched well with atom probe data.

  20. Bootstrapping N}=3 superconformal theories

    NASA Astrophysics Data System (ADS)

    Lemos, Madalena; Liendo, Pedro; Meneghelli, Carlo; Mitev, Vladimir

    2017-04-01

    We initiate the bootstrap program for N=3 superconformal field theories (SCFTs) in four dimensions. The problem is considered from two fronts: the protected subsector described by a 2 d chiral algebra, and crossing symmetry for half-BPS operators whose superconformal primaries parametrize the Coulomb branch of N=3 theories. With the goal of describing a protected subsector of a family of N=3 SCFTs, we propose a new 2 d chiral algebra with super Virasoro symmetry that depends on an arbitrary parameter, identified with the central charge of the theory. Turning to the crossing equations, we work out the superconformal block expansion and apply standard numerical bootstrap techniques in order to constrain the CFT data. We obtain bounds valid for any theory but also, thanks to input from the chiral algebra results, we are able to exclude solutions with N=4 supersymmetry,allowingustozoominonaspecific N=3 SCFT.

  1. Strain relaxation in (0001) AlN/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Bourret, Alain; Adelmann, Christoph; Daudin, Bruno; Rouvière, Jean-Luc; Feuillet, Guy; Mula, Guido

    2001-06-01

    The strain-relaxation phenomena during the early stages of plasma-assisted molecular-beam epitaxy growth of lattice-mismatched wurtzite (0001) AlN/GaN heterostructures have been studied by real-time recording of the in situ reflection high-energy electron diffraction (RHEED), ex situ transmission electron microscopy (TEM), and atomic-force microscopy. A pseudo-two-dimensional layer-by-layer growth is observed at substrate temperatures of 640-660 °C, as evidenced by RHEED and TEM. However, the variation of the in-plane lattice parameter during growth and after growth has been found to be complex. Three steps have been seen during the deposition of lattice-mismatched AlN and GaN layers: they were interpreted as the succession of the formation of flat platelets, 3-6 monolayers high (0.8-1.5 nm) and 10-20 nm in diameter, their partial coalescence, and gradual dislocation introduction. Platelet formation leads to elastic relaxation as high as 1.8%, i.e., a considerable part of the AlN/GaN lattice mismatch of 2.4%, and can be reversible. Platelets are always observed during the initial stages of growth and are almost insensitive to the metal/N ratio. In contrast, platelet coalescence and dislocation introduction are very dependent on the metal/N ratio: no coalescence occurs and the dislocation introduction rate is higher under N-rich conditions. In all cases, the misfit dislocation density, as measured by the irreversible relaxation, is initially of the order of 7×1011 cm-2 and decreases exponentially with the layer thickness. These results are interpreted in the framework of a model that emphasizes the important role of the flat platelets for dislocation nucleation.

  2. Band offsets of non-polar A-plane GaN/AlN and AlN/GaN heterostructures measured by X-ray photoemission spectroscopy

    PubMed Central

    2014-01-01

    The band offsets of non-polar A-plane GaN/AlN and AlN/GaN heterojunctions are measured by X-ray photoemission spectroscopy. A large forward-backward asymmetry is observed in the non-polar GaN/AlN and AlN/GaN heterojunctions. The valence-band offsets in the non-polar A-plane GaN/AlN and AlN/GaN heterojunctions are determined to be 1.33 ± 0.16 and 0.73 ± 0.16 eV, respectively. The large valence-band offset difference of 0.6 eV between the non-polar GaN/AlN and AlN/GaN heterojunctions is considered to be due to piezoelectric strain effect in the non-polar heterojunction overlayers. PMID:25258600

  3. Proof without Words: (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1

    ERIC Educational Resources Information Center

    Khattri, Sanjay Kumar

    2008-01-01

    We present a pictorial proof of the inequation (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1]. The inequation is also confirmed through the Taylor expansion and alternating series theorem.

  4. Proof without Words: (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1

    ERIC Educational Resources Information Center

    Khattri, Sanjay Kumar

    2008-01-01

    We present a pictorial proof of the inequation (1 + 1/n)[superscript n] less than e less than (1 + 1/n)[superscript n+1]. The inequation is also confirmed through the Taylor expansion and alternating series theorem.

  5. Interaction of carbon atoms with Fe n, Fe n-, and Fe n+ clusters ( n=1-6)

    NASA Astrophysics Data System (ADS)

    Gutsev, Gennady L.; Bauschlicher, Charles W.

    2003-06-01

    The electronic and geometrical structures of the ground and exited states of Fe nC, Fe nC -, and Fe nC + ( n=1-6) are computed using density functional theory (DFT). Several exchange-correlation functionals are tested on FeC, for which a number of experimental results are available for comparison. Fe 2C and Fe 2C - have triangular high-spin ground states, while the ground state of Fe 2C + is a linear asymmetric Fe-C-Fe doublet whose spins at the iron sites are antiferromagnetically coupled. The natural bond analysis (NBO) allows us to qualitatively describe the nature of super exchange coupling in Fe 2C +. There is a competition between twofold and threefold sites in the Fe 3C species. Carbon is threefold coordinated in the Fe 4C and Fe 6C species, while it is fourfold coordinated in the Fe 5C clusters. Generally, attachment of a carbon atom reduces the number of unpaired electrons of an iron cluster. The maximum reduction of four is found for the largest cluster, Fe 6C. The C-Fe n bond energies in the neutral clusters are rather high, ranging from 5.5 (Fe 2C) to 6.5 eV (Fe 6C). These energies are not significantly affected by attachment or detachment of an electron to/from a Fe nC cluster. Surprisingly, the Fe-Fe n-1 , Fe-Fe n-1 C, and Fe-Fe nC bond energies are found to be nearly the same for given n. The results of our computations are in reasonable agreement with experimental data.

  6. H enhancement of N vacancy migration in GaN.

    SciTech Connect

    Wixom, Ryan R.; Wright, Alan Francis

    2005-06-01

    We have used density functional theory to investigate diffusion of V{sub N}{sup +} in the presence of H{sup +}. Optimal migration pathways were determined using the climbing image nudged elastic band and directed dimer methods. Our calculations indicate that the rate-limiting barrier for VN{sub N}{sup +} migration will be reduced by 0.58 eV by interplay with H{sup +}, which will enhance migration by more than an order of magnitude at typical GaN growth temperatures.

  7. Large N phase transitions in massive N = 2 gauge theories

    SciTech Connect

    Russo, J. G.

    2014-07-23

    Using exact results obtained from localization on S{sup 4}, we explore the large N limit of N = 2 super Yang-Mills theories with massive matter multiplets. In this talk we discuss two cases: N = 2* theory, describing a massive hypermultiplet in the adjoint representation, and super QCD with massive quarks. When the radius of the four-sphere is sent to infinity these theories are described by solvable matrix models, which exhibit a number of interesting phenomena including quantum phase transitions at finite 't Hooft coupling.

  8. 40 CFR 721.8100 - Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy-ethyl) tal-lo-wa-mine oxide phos-phate. 721.8100... Substances § 721.8100 Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy... section: Potassium N,N-bis (hydroxyethyl) cocoamine oxide phosphate (CAS Number 855712-26-1), and...

  9. 40 CFR 721.8100 - Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy-ethyl) tal-lo-wa-mine oxide phos-phate. 721.8100... Substances § 721.8100 Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy... section: Potassium N,N-bis (hydroxyethyl) cocoamine oxide phosphate (CAS Number 855712-26-1), and...

  10. 40 CFR 721.8100 - Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) cocoamine oxide phosphate, and potassium N,N-bis (hy-droxy-ethyl) tal-lo-wa-mine oxide phos-phate. 721.8100... Substances § 721.8100 Potassium N,N-bis (hydroxy-ethyl) cocoamine oxide phosphate, and potassium N,N-bis (hy... section: Potassium N,N-bis (hydroxyethyl) cocoamine oxide phosphate (CAS Number 855712-26-1), and...

  11. 40 CFR 721.10175 - 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd. acyl) derivs., inner salts. 721.10175 Section 721... 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd....

  12. 40 CFR 721.10175 - 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd. acyl) derivs., inner salts. 721.10175 Section 721... 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18 and C18-unsatd....

  13. Metal-free functionalization of N,N-dialkylanilines via temporary oxidation to N,N-dialkylaniline N-oxides and group transfer.

    PubMed

    Lewis, Robert S; Wisthoff, Michael F; Grissmerson, J; Chain, William J

    2014-07-18

    A simple set of protocols for the controlled elaboration of anilines is reported allowing access to a diverse array of aminophenols, aminoarylsulfonates, alkylated anilines, and aminoanilines in 29-95% yield in a single laboratory operation from easily isolable, bench-stable N,N-dialkylaniline N-oxides. The introduction of new C-O, C-C, and C-N bonds on the aromatic ring is made possible by a temporary increase in oxidation level and excision of a weak N-O bond.

  14. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND... solvents in cotton defoliant formulations containing thidiazuron and diuron as active ingredients. (b) N-(n...

  15. Electron beam induced current profiling of the p-ZnO:N/n-GaN heterojunction

    SciTech Connect

    Przeździecka, E. Stachowicz, M.; Chusnutdinow, S.; Jakieła, R.; Kozanecki, A.

    2015-02-09

    The high quality p-n structures studied consist of nitrogen doped ZnO:N films grown by plasma assisted molecular beam epitaxy on n-type GaN templates. The nitrogen concentration, determined by secondary ion mass spectroscopy, is about 1 × 10{sup 20} cm{sup −3}. Temperature dependent photoluminescence studies confirm the presence of acceptor centers with an energy level lying approximately 130 meV above the valence band. The maximum forward-to-reverse current ratio I{sub F}/I{sub R} in the obtained p-n diodes is about 10{sup 7} at ±5 V, which is 2–5 orders of magnitude higher than previously reported for this type of heterojunctions. Electron-beam-induced current measurements confirm the presence of a p–n junction, located at the p-ZnO/n-GaN interface. The calculated diffusion length and activation energy of minority carriers are presented. The heterostructures exhibit strong absorption in the UV range with a four orders of magnitude high bright-to-dark current ratio.

  16. NpN-GaN/InxGa1-xN/GaN heterojunction bipolar transistor on free-standing GaN substrate

    NASA Astrophysics Data System (ADS)

    Lochner, Zachary; Jin Kim, Hee; Lee, Yi-Che; Zhang, Yun; Choi, Suk; Shen, Shyh-Chiang; Doug Yoder, P.; Ryou, Jae-Hyun; Dupuis, Russell D.

    2011-11-01

    Data and analysis are presented for NpN-GaN/InGaN/GaN double-heterojunction bipolar transistors (HBTs) grown and fabricated on a free-standing GaN (FS-GaN) substrate in comparison to that on a sapphire substrate to investigate the effect of dislocations in III-nitride HBT epitaxial structures. The performance characteristics of HBTs on FS-GaN exhibit a maximum collector current density of ˜12.3 kA/cm2, dc current gain of ˜90, and maximum differential gain of ˜120 without surface passivation, representing a substantial improvement over similar devices grown on sapphire. This is attributed to the reduction in threading dislocation density afforded by using a homoepitaxial growth on a high-crystalline-quality substrate. The minority carrier diffusion length increases significantly owing to not only a mitigated carrier trap effect via fewer dislocations, but also possibly reduced microscopic localized states.

  17. Sustainable development in an N-rich/n-poor world.

    PubMed

    Perrings, Charles; Kinzig, Ann; Halkos, George

    2014-11-01

    Sustainable development requires that per capita inclusive wealth-produced, human, and natural capital-does not decline over time. We investigate the impact of changes in nitrogen on inclusive wealth. There are two sides to the nitrogen problem. Excess use of nitrogen in some places gives rise to N-pollution, which can cause environmental damage. Insufficient replacement of nitrogen in other places gives rise to N-depletion, or loss of nutrient stocks. Neither is explicitly accounted for in current wealth measures, but both affect wealth. We calculate an index of net N-replacement, and investigate its relationship to wealth. In countries with low levels of relative N-loss, we find that the uncompensated loss of soil nitrogen in poorer countries is associated with declining rates of growth of inclusive per capita wealth. What is less intuitive is that increasing fertilizer application in both rich and poor countries can increase per capita inclusive wealth.

  18. AlGaN/GaN plasmonic terahertz electronic devices

    NASA Astrophysics Data System (ADS)

    Shur, Michael

    2014-03-01

    A very large electron sheet density and a relatively long momentum relaxation time of the two-dimensional electron gas in III-N heterostructures makes this materials system to be very attractive for plasmonic electronics applications.

  19. Blockade involving high- n, n ~ 300 , strontium Rydberg atoms

    NASA Astrophysics Data System (ADS)

    Yoshida, Shuhei; Burgdörfer, Joachim; Zhang, Xinyue; Dunning, F. Barry

    2016-05-01

    The blockade of high- n strontium n1F3 Rydberg states contained in a hot atomic beam is investigated both theoretically and experimentally. One difficulty in such experiments is that, once created, Rydberg atoms move out of the excitation volume reducing blockade effects. While the effects of such motion are apparent, the data provide strong evidence of blockade, consistent with theoretical predictions. Because of their relatively high angular momentum (L = 3) , a pair of n1F3 Rydberg atoms have many degenerate states whose degeneracy is removed by Rydberg-Rydberg interactions yielding a high density of states near the target energy. To evaluate the effect of blockade not only the energy shifts but also the modification of the oscillator strengths for excitation have to be taken into account. The n-scaling of the interactions and the importance of high-order multipoles will also be discussed. Research supported by the NSF and Robert A. Welch Foundation.

  20. Investigation of 110Cd with the (n ,n' γ) reaction

    NASA Astrophysics Data System (ADS)

    Garrett, P. E.; Bangay, J.; Diaz Varela, A.; Green, K. L.; Jigmeddorj, B.; Sumithrarachchi, C.; Jolie, J.; Warr, N.; Hannant, C. D.; Orce, N.; Yates, S. W.

    2013-10-01

    Excited states in 110Cd have been investigated with the (n ,n' γ) reaction using monoenergetic neutrons. Excitation functions, using neutron energies in the range of 2 MeV to 3.4 MeV were collected, and γ-ray angular distributions at neutron energies of 2.6, 2.9, and 3.4 MeV were performed. The (n ,n' γ) results were complemented with γγ coincidences from a 110In β-decay experiment (see contribution by A. Diaz Varela) performed at TRIUMF. This has resulted in a comprehensive level scheme for 110Cd below ~ 3 MeV, including stringent limits on unobserved transitions. Level lifetimes were extracted using the Doppler shift attenuation technique. Comparison of the results with simplified model expectations suggests that the low-lying structure of 110Cd is that of a deformed γ-soft rotor, rather than a spherical vibrator.

  1. Experimental observation of N00N state Bloch oscillations.

    PubMed

    Lebugle, Maxime; Gräfe, Markus; Heilmann, René; Perez-Leija, Armando; Nolte, Stefan; Szameit, Alexander

    2015-09-22

    Bloch oscillations of quantum particles manifest themselves as periodic spreading and relocalization of the associated wave functions when traversing lattice potentials subject to external gradient forces. Albeit this phenomenon is deeply rooted into the very foundations of quantum mechanics, all experimental observations so far have only contemplated dynamics of one and two particles initially prepared in separable local states. Evidently, a more general description of genuinely quantum Bloch oscillations will be achieved on excitation of a Bloch oscillator by nonlocal states. Here we report the observation of Bloch oscillations of two-particle N00N states, and discuss the nonlocality on the ground of Bell-like inequalities. The time evolution of two-photon N00N states in Bloch oscillators, whether symmetric, antisymmetric or partially symmetric, reveals transitions from particle antibunching to bunching. Consequently, the initial states can be tailored to produce spatial correlations akin to those of bosons, fermions and anyons, presenting potential applications in photonic quantum simulation.

  2. Graphene in ohmic contact for both n-GaN and p-GaN

    SciTech Connect

    Zhong, Haijian; Liu, Zhenghui; Shi, Lin; Xu, Gengzhao; Fan, Yingmin; Huang, Zengli; Wang, Jianfeng; Ren, Guoqiang; Xu, Ke

    2014-05-26

    The wrinkles of single layer graphene contacted with either n-GaN or p-GaN were found both forming ohmic contacts investigated by conductive atomic force microscopy. The local I–V results show that some of the graphene wrinkles act as high-conductive channels and exhibiting ohmic behaviors compared with the flat regions with Schottky characteristics. We have studied the effects of the graphene wrinkles using density-functional-theory calculations. It is found that the standing and folded wrinkles with zigzag or armchair directions have a tendency to decrease or increase the local work function, respectively, pushing the local Fermi level towards n- or p-type GaN and thus improving the transport properties. These results can benefit recent topical researches and applications for graphene as electrode material integrated in various semiconductor devices.

  3. New metabolic pathway for N,N-dimethyltryptamine

    SciTech Connect

    Hryhorczuk, L.M.; Rainey, J.M. Jr.; Frohman, C.E.; Novak, E.A.

    1986-01-01

    N,N-Dimethyltryptamine (DMT) undergoes a major structural alteration when added to whole human blood or its red blood cells in vitro. A new high-pressure liquid chromatography (HPLC) peak is present in extracts of these treated tissues. The compound responsible for this peak has been identified by ultraviolet spectrophotometry and by mass spectrometry as dimethylkynuramine (DMK). The enzyme responsible for this appears to be different from tryptophan 2,3-dioxygenase and also from indoleamine 2,3-dioxygenase.

  4. Photoionization studies of (BH3)n (n=1,2)

    NASA Astrophysics Data System (ADS)

    Ruščić, B.; Mayhew, C. A.; Berkowitz, J.

    1988-05-01

    The results of photoionization mass spectrometric studies on B2H6, and BH3 (produced by pyrolysis of B2H6) are presented. The photoion yield curves of B2H+n (n=2-6) and BH+n (n=2-3) from B2H6, as well as BH+n (n=1-3) from BH3 have been obtained. It is shown that the combination of appearance potential measurements for BH+3 (B2H6) and BH+3 (BH3) yields a poor upper limit for -ΔHdimerization, 0 K (BH3) of 52.7 kcal/mol, while the combination of BH+2 (B2H6) and BH+2 (BH3) provides a better upper limit (46.6±0.6 kcal/mol) for this quantity. However, the threshold for BH+ (BH3), combined with auxiliary data, provides the best current experimental value, (34.3-39.1)±2 kcal/mol. This experimental value is in good agreement with a recent ab initio calculation, and is arrived at by using the best current estimate of ΔHf(B2H6), rather than a radically different value proposed in that paper. The ionization potential of BH3, ΔHf (BH+2), and the atomization energy of BH3 obtained experimentally are in excellent agreement with other ab initio calculations. The upper limits on heats of formation for the ionic species B2H+n (n=2-6) are obtained, and plausible structures are discussed for these species, based on the current energetics and various ab initio calculations. Finally, the fragmentation behavior of photoions from diborane is shown to have a more facile explanation by quasiequilibrium theory than by a molecular orbital picture, with the probable exception of BH+3 (B2H6).

  5. Chlorophyll Determination in Intact Tissues Using N,N-Dimethylformamide

    PubMed Central

    Moran, Rami; Porath, Dan

    1980-01-01

    Photosynthetic pigments from etiolated cucumber (Cucumis sativus var. Beit Alpha improved, Hazera Co., Gedera) cotyledons were extracted by direct immersion of the intact cotyledons into the solvent N,N-dimethylformamide (DMF). The solvent is especially efficient when pigment concentration is low; time and tools are saved and the loss of pigment that usually occurs in more complicated extraction procedures is prevented. The specific absorption coefficient of chlorophyll a in DMF was also determined. PMID:16661217

  6. Incomplete nested dissection for solving n by n grid problems

    NASA Technical Reports Server (NTRS)

    George, A.; Poole, W. G., Jr.; Voigt, R. G.

    1978-01-01

    Nested dissection orderings are known to be very effective for solving sparse positive definite linear systems which arise from n by n grid problems. In this paper we consider incomplete nested dissection, an ordering which corresponds to the premature termination of nested dissection. Analyses of the arithmetic and storage requirements for incomplete nested dissection are given and the ordering is shown to be competitive with nested dissection with regard to arithmetic operations and superior to that ordering in storage requirements.

  7. [N,N-Bis(diphenyl-phosphino)isopropyl-amine]dibromidonickel(II).

    PubMed

    Hapke, Marko; Wöhl, Anina; Peitz, Stephan; Müller, Bernd H; Spannenberg, Anke; Rosenthal, Uwe

    2009-02-06

    The title compound, [NiBr(2)(C(27)H(27)NP(2))], was synthesized by the reaction of NiBr(2)(dme) (dme is 1,2-dimethoxy-ethane) with N,N-bis-(diphenyl-phosphino)isopropyl-amine in methanol/tetra-hydro-furan. The nickel(II) center is coordinated by two P atoms of the chelating PNP ligand, Ph(2)PN(iPr)PPh(2), and two bromide ions in a distorted square-planar geometry.

  8. The effect of N-substituted alkyl groups on the anticonvulsant activities ofN-Cbz-alpha-amino-N-alkylsuccinimides.

    PubMed

    Lee, J; Son, K; Jung, K; Choi, J; Park, M

    1997-02-01

    For the purpose of defining the effects of theN-substituted alkyl groups on the anticonvulsant activities ofN-Cbz-alpha-aminosuccinimides, various (R)-and(S)-N-alkyl substitutedN-Cbz-alpha-aminosuccinimides (1 and2) were prepared from the corresponding (R)-and(S)-N-Cbz-aspartic acid by using known reaction and were evaluated the anticonvulsant activies in the MES and PTZ tests, including their neurotoxicities. The most active compound in the MES test was(R)-N-Cbz-alpha-amino-N-methylsuccinimide (1b) (ED(50)=52.5 mg/kg, Pl-3.2). And in case of the PTZ test,(R)-N-Cbz-alpha-amino-N-ethylsuccinimide (1c) was the most active compound (ED(50)=32.5 mg/kg, Pl=3.1). The order of anticonvulsant activities of these compounds against the MES test, as judged from the ED(50) values for theR series (1), wasN-methyl >N-isobutyl > non-substituted >N-ethyl,N-allyl >N-benzyl compound; for theS series (2)N-methyl >N-allyl > non-substituted >N-isobutyl >N-ethyl >N-benzyl compound. The anticonvulsant activities in the PTZ tests of these compounds exhibited somewhat different pattern; for theR series (1)N-ethyl >N-methyl >N-isobutyl> non-substituted >N-allyl >N-benzyl compound in order of decreasing activity; forS series (2)N-ethyl >N-allyl, non-substituted >N-isobutyl >N-methyl >N-benzyl compound in order of decreasing activity.

  9. Large N correlation functions N = 2 superconformal quivers

    NASA Astrophysics Data System (ADS)

    Pini, Alessandro; Rodriguez-Gomez, Diego; Russo, Jorge G.

    2017-08-01

    Using supersymmetric localization, we consider four-dimensional N = 2 superconformal quiver gauge theories obtained from Z_n orbifolds of N = 4 Super Yang-Mills theory in the large N limit at weak coupling. In particular, we show that: 1) The partition function for arbitrary couplings can be constructed in terms of universal building blocks. 2) It can be computed in perturbation series, which converges uniformly for |λ I | < π2, where λ I are the 't Hooft coupling of the gauge groups. 3) The perturbation series for two-point functions can be explicitly computed to arbitrary orders. There is no universal effective coupling by which one can express them in terms of correlators of the N = 4 theory. 4) One can define twisted and untwisted sector operators. At the perturbative orbifold point, when all the couplings are the same, the correlators of untwisted sector operators coincide with those of N = 4 Super Yang-Mills theory. In the twisted sector, we find remarkable cancellations of a certain number of planar loops, determined by the conformal dimension of the operator.

  10. A HΛ4+n+n model of HΛ6

    NASA Astrophysics Data System (ADS)

    Gibson, B. F.; Afnan, I. R.

    2013-09-01

    A three-body calculation for the HeΛ6 and HΛ6 hypernuclei, in which the respective cores are He4 and HΛ4, has been initiated. The interactions in the HeΛ6 system are reasonably well known. For example, the Λn interaction is approximately determined by bubble-chamber Λ-p scattering data, the He4-Λ interaction can be fitted to the HeΛ5 binding energy, and the He4-n interaction can be fitted to α-n scattering data. For He4-n the s-wave can be modeled alternatively as a repulsive potential (Eskandarian and Afnan, 1992 [1]) or as an attractive potential with a forbidden bound state (Lehman, 1982 [2]). We examine the effect of these alternatives on He6 and Li6, because the interaction comes into play in modeling HeΛ6 as well as in our HΛ4+n+n model of HΛ6, where the valence neutrons are Pauli blocked from the s-shell of the core.

  11. InGaN quantum dot formation mechanism on hexagonal GaN/InGaN/GaN pyramids.

    PubMed

    Lundskog, A; Palisaitis, J; Hsu, C W; Eriksson, M; Karlsson, K F; Hultman, L; Persson, P O Å; Forsberg, U; Holtz, P O; Janzén, E

    2012-08-03

    Growing InGaN quantum dots (QDs) at the apex of hexagonal GaN pyramids is an elegant approach to achieve a deterministic positioning of QDs. Despite similar synthesis procedures by metal organic chemical vapor deposition, the optical properties of the QDs reported in the literature vary drastically. The QDs tend to exhibit either narrow or broad emission lines in the micro-photoluminescence spectra. By coupled microstructural and optical investigations, the QDs giving rise to narrow emission lines were concluded to nucleate in association with a (0001) facet at the apex of the GaN pyramid.

  12. Heats of NF(sub n) (n= 1-3) and NF(sub n)(+)(n = 1-3)

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Arnold, James (Technical Monitor)

    1998-01-01

    Accurate heats of formation are computed for NF(sub n) and NF(sub n)(+), for n = 1-3. The geometries and the vibrational frequencies are determined at the B3LYP level of theory. The energetics are determined at the CCSD(T) level of theory. Basis set limit values are obtained by extrapolation. In those cases where the CCSD(T) calculations become prohibitively large, the basis set extrapolation is performed at the MP2 level. The temperature dependence of the heat of formation, heat capacity, and entropy are computed for the temperature range 300 to 4000 K and fit to a polynomial.

  13. Laboratory experiments for Titan's ionosphere : the chemistry of N2+, N+, and N2++ nitrogen ions

    NASA Astrophysics Data System (ADS)

    Thissen, R.; Alcaraz, C.; Dutuit, O.; Nicolas, C.; Soldi-Lose, H.; Zabka, J.; Franceschi, P.

    Laboratory experiments for Titan's ionosphere : the chemistry of N+ , N+ , and N2+ nitrogen ions 2 2 R. Thissen (1), C. Alcaraz (1), O. Dutuit (1), C. Nicolas (2), H. Soldi-Lose (3), J. Zabka (4), P. Franceschi (5) (1) LCP, Bât. 350, Centre Universitaire Paris-Sud, F-91405 Orsay Cedex, France, (2) Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette, France, (3) Institut für Chemie, Fachgruppe Organische Chemie, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, (4) J. Heyrovsky Institute of Physical Chemistry, Dolejskova 3, CZ 18223 Praha 8 - Kobylisy, Czech Republik, (5) Dept. of Physics, University of Trento, Via Sommarive 14, 38050 Povo (TN), Italy (christian.alcaraz@lcp.u-psud.fr) N2 is the major neutral componant of Titan's atmosphere, its ionisation by solar radiation and by magnetospheric electron impact is the most important production of ions in Titan's ionosphere. These primary processes not only lead to N+ molecular 2 monocations but also to N+ atomic ions and to N2+ molecular dications, which can 2 pertain some internal or translational excitation. This contribution will summarize our efforts to caracterize in gaz phase laboratory experiments the reactivity of the nitrogen ions with the most important neutral targets of the Titan's atmosphere [1-3]: • N+ + CH4 , C2 H2 , and C2 H6 2 • N+ (3 P, 1 D) + CH4 , and C2 H4 • N2+ + N2 , CH4 , and C2 H4 2 In this work, particular attention has been paid on the effect of internal and/or translational excitation of the primary nitrogen ions on the rate constant and branching ratio of these ion-molecule reactions. The results from these studies have been compared to the literature values when available and some significant differences have been found. These new values have been used as input data in 1D models of the Titan's ionosphere to show the effect on the final density profiles of the main ions [4] and to demonstrate the existence of a N2+2 dication

  14. Fabrication, welding and heat treatment of nickel alloys UNS N08800, N08810, N08811, and N08825

    SciTech Connect

    Tassen, C.S.; Smith, G.D.; Mannan, S.K.; Hinshaw, E.B.

    1996-10-01

    The selection of materials of construction, including the final heat treatment, is a major factor in the success of many processes in an oil refinery. Alloys UNS N08800, N08810, N08811, and N08825 are each used in refinery applications and have the excellent corrosive resistance and mechanical properties required for the demanding service conditions. These materials always undergo some amount of fabrication or welding prior to going into service. In many cases, a post-weld/fabrication heat treatment is not necessary; however, in some cases, it is beneficial to heat treat these alloys after fabrication and welding. This paper will describe guidelines for when a post-weld/fabrication heat treatment should be considered and applicable welding products and heat treat procedures.

  15. Magnetic field effect on photocurrent in N,N'-di(naphthalene-l-yl)-N,N'-diphenyl-benzidine (NPB)

    NASA Astrophysics Data System (ADS)

    Li, B. K.; Chen, W. J.; Lam, M. K.; Cheah, K. W.; Wang, J. N.

    2009-11-01

    We studied organic magnetoresistance (OMAR) and magneto-photocurrent (MPC) in ITO/N,N'-di(naphthalene-l-yl)-N,N'-diplienyl-benzidine (NPB)/A1 sandwich devices with NPB thicknesses of 50 nm. Without illumination, no OMAR is observable. While the MPC curves are found to have different line shapes containing a low field and a high field component, depending on excitation photon energy and applied bias. The analysis of experimental results indicate that: (i) the magnetic field effects in NPB is associated with excitonic states, and (ii) the dissociation of singlet excitons is associated to the high field component and triplet-exciton-charge interaction is to the low field component in MPC curves.

  16. Basic studies on N''-ursodeoxycholyldiethylenetriamine-N,N,N'-triacetic acid for the dissolution of calcified gallstones.

    PubMed

    Takahashi, M; Konishi, T; Maeda, Y; Fukuzawa, M; Nishida, T; Ohya, T; Katayama, K; Kakehi, N; Sakakura, H; Takagi, A; Maeda, M; Ohama, H

    1998-06-01

    A novel calcium-chelating agent, N"-ursodeoxycholyldiethylenetriamine-N,N,N'-triacetic acid (UDCA-DTTA), was synthesized to study its ability to dissolve calcified gallstones. The chelating activity of the compound was demonstrated by dissolving calcium carbonate in vitro at a high dissolution rate. In the presence of the agent, sliced human gallstone with a composition of more than 50% calcium bilirubinate was thoroughly dissolved, indicating that calcium bilirubinate was dissolved from the gallstone. The ability to dissolve calcium was comparable to that of EDTA. However, the laminar structure of the sliced gallstone did not disappear in the presence of EDTA, whereas the structure disappeared in the presence of UDCA-DTTA. All these results indicate that UDCA-DTTA is an interesting compound as a parent substance for developing a prodrug for an oral or intravenous agent to dissolve calcium-containing gallstones.

  17. [Effects of irrigation mode and N application rate on cotton field fertilizer N use efficiency and N losses].

    PubMed

    Wang, Xiao-Juan; Wei, Chang-Zhou; Zhang, Jun; Dong, Peng; Wang, Juan; Zhu, Qi-Chao; Wang, Jin-Xin

    2012-10-01

    A field experiment was conducted to study the effects of different irrigation modes (drip irrigation and furrow irrigation) and different N application rates (0, 240, 360 and 480 kg N x hm(-2)) on the fertilizer N use efficiency and N losses in a cotton field in Xinjiang, Northwest China. The main N cycling pathways, such as the N uptake by cotton plant, NO3(-)-N residual in soil, NH3 volatilization, NO3(-)-N leaching, and nitrification-denitrification, were quantitatively monitored. Compared with furrow irrigation, drip irrigation increased the seed cotton yield, plant N uptake, and fertilizer N use efficiency significantly. The NO3(-)-N residual in soil was significantly greater under furrow irrigation than under drip irrigation. With the application of fertilizer N, the N loss from NH3 volatilization under drip irrigation occupied 0.06% -0.14% of applied N, and was significantly greater than that under furrow irrigation. The N loss from NO3(-)-N leaching under drip irrigation and furrow irrigation was 4.4% and 8.8% of the applied N, respectively. Compared with furrow irrigation, drip irrigation could significantly decrease the NO3(-)-N leakage rate in leakage water. The nitrification-dinetrification loss under drip irrigation and furrow irrigation was 17.9% and 16.8% of the applied N, respectively. It was suggested that NO3(-)-N leaching and nitrification-denitrification were the main N losses in the cotton fields of Xinjiang.

  18. Fast neutron scattering cross sections for terbium-159 via the (n,n'gamma) and (n,n') techniques

    NASA Astrophysics Data System (ADS)

    Seo, Pil-Neyo

    2001-08-01

    Scattering cross sections for fast neutrons were measured for low-lying levels of 159Tb, a deformed odd-A nucleus. Levels from 400 keV up to 1000 keV in excitation were studied by the (n,n'γ) technique, while elastic and inelastic scattering for the lower lying excited states were studied via the (n,n') technique. For the (n,n'γ) experiment, a Ge detector was used in conjunction with the pulsed beam time-of-flight technique to observe de-excitation gamma decays. A NaI(Tl) annulus was used to suppress signals caused by Compton scattered gamma rays. Gamma-ray production cross sections were measured in the 400- to 1000-keV incident neutron energy range in 50-keV intervals at a scattering angle of 125°. Thirty six gamma-ray transitions from 16 levels of 159.Tb were observed and placed in the decay scheme. Neutron level cross sections were inferred from the differential gamma- ray production cross sections. Neutron elastic and inelastic scattering angular distributions for this nuclide were measured via the time-of-flight technique at incident neutron energies of 575 keV and 995 keV. The neutron detector consisted of a plastic scintillator mounted on a fast photomultiplier tube. Measurements were made at 11 angles from 35° to 135° in 10-degree steps for 995 keV and at 5 angles for 575 keV. Neutrons were produced in a thin lithium target using the 7Li(p,n)7Be reaction with protons generated by the University of Massachusetts Lowell Van de Graaff Accelerator. Level cross section results using the (n,n'γ) technique are compared with the those using the (n,n') technique for lower-lying levels, 241 keV(9/2+), a three-level cluster of 348 keV(5/2+), 363 keV(5/2-), and 388 keV(7/2-), and 428 keV(7/2+) states. The results are also compared with previous work and to the ENDF/B-VI, JEF-2, and JENDL-3 evaluations.

  19. Fabrication of TiN/AlN/TiN tunnel junctions

    NASA Astrophysics Data System (ADS)

    Nakayama, Takeru; Naruse, Masato; Myoren, Hiroaki; Taino, Tohru

    2016-11-01

    We have fabricated TiN/AlN/TiN tunnel junctions with an epitaxial layer. The critical temperature of TiN can be changed in the range from 0.5 to 5.0 K. Therefore, it is easy to set 5.0 K as the target critical temperature. When a Superconducting Tunnel Junction (STJ) is operated as a photon detector, it is necessary to cool it to within 0.1 K of the critical temperature in consideration of the noise of the thermally stimulated currents. Because 0.3 K was desirable, as for the manufacture of general purpose photon detectors, the critical temperature 5.0 K. TiN and AlN films were deposited by dc and rf magnetron sputtering in a load-lock sputtering system at ambient substrate temperatures. The junctions have a gap voltage of Vg = 1.1 mV, and critical current density of Jc = 0.24 A/cm2, and Rsg/Rn of 7.2, and low subgap leakage current (Isub@ 500 μV = 180 nA). We report our experiment system, the manufacture method and the junction properties in this paper.

  20. Semantic priming modulates the N400, N300, and N400RP.

    PubMed

    Franklin, Michael S; Dien, Joseph; Neely, James H; Huber, Elizabeth; Waterson, Lauren D

    2007-05-01

    To determine whether ERP components can differentiate between the semantic priming mechanisms of automatic spreading activation, expectancy, and semantic matching. The present study manipulated two factors known to differentiate semantic priming mechanisms: associations between words (forward, backward, and symmetrical) and prime-target stimulus onset asynchrony (SOA). Twenty-six participants were tested in each SOA condition while high-density 128-channel data were collected. Principal components analysis was applied to separate the ERP components. Priming was observed for all conditions. Three semantic components were present: (1) the standard N400 effect for symmetric and forward priming pairs at both short and long SOAs, (2) an N300 for the long SOA symmetric priming pairs, and (3) a right-lateralized posterior N400RP for long SOA backward priming pairs. Results suggest that the N300 reflects expectancy, but only for categorical and/or semantic similarity priming. Results further suggest that the N400RP is a replicable ERP component that responds to semantic matching. There is also some evidence that the N400 indirectly responds to both ASA and expectancy, perhaps as part of a post-lexical updating process and that backward priming at short SOAs is different from that at long SOAs. Improved understanding of the semantic properties of the N400 and related ERP components may increase their utility for understanding language processes and for diagnostic purposes.

  1. Transnitrosation of non-mutagenic N-nitrosoproline forms mutagenic N-nitroso-N-methylurea.

    PubMed

    Inami, Keiko; Shiino, Junko; Hagiwara, Shin; Takeda, Kei; Mochizuki, Masataka

    2015-07-01

    N-Nitroso-N-methylurea (NMU) is a potent carcinogen and suspected as a cause of human cancer. In this study, mutagenic NMU was detected by HPLC after the transnitrosation of non-mutagenic N-nitrosoproline (NP) to N-methylurea in the presence of thiourea (TU) under acidic conditions. The structure of NMU was confirmed by comparing (1)H NMR and IR spectra with that of authentic NMU after fractionation by column chromatography. Furthermore, a fraction containing NMU formed by transnitrosation was mutagenic in Salmonella typhimurium TA1535. NMU was formed in the reaction of NP and N-methylurea in the presence of 1,1,3,3-tetramethylthiourea (TTU) or 1,3-dimethylthiourea in place of TU as an accelerator. The reaction rate constants (k) for NMU formation were correlated with their nucleophilicity of sulfur atom in thioureas. The N-methylurea concentration did not affect the NMU formation, whereas the rate of NMU formation correlated linearly with concentrations of NP, TTU and oxonium ion. The observed kinetics suggests a mechanism by which the nitroso group was transferred directly from the protonated NP to the thiourea then to N-methylurea to form NMU. The rate-determining step was the formation of the complex with the protonated NP and thiourea. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. More on N=8 attractors

    SciTech Connect

    Ceresole, Anna; Ferrara, Sergio; Gnecchi, Alessandra; Marrani, Alessio

    2009-08-15

    We examine a few simple extremal black hole configurations of N=8, d=4 supergravity. We first elucidate the relation between the BPS Reissner-Noerdstrom black hole and the non-BPS Kaluza-Klein dyonic black hole. Their classical entropy, given by the Bekenstein-Hawking formula, can be reproduced via the attractor mechanism by suitable choices of symplectic frame. Then, we display the embedding of the axion-dilaton black hole into N=8 supergravity.

  3. N-Consecutive-Phase Encoder

    NASA Technical Reports Server (NTRS)

    Divsalar, Dariush; Lee, Ho-Kyoung; Weber, Charles

    1995-01-01

    N-consecutive-phase encoder (NCPE) is conceptual encoder for generating alphabet of N consecutive full-response continuous-phase-modulation (CPM) signals. Enables use of binary preencoder of higher rate than used with simple continuous-phase encoder (CPE). NCPE makes possible to achieve power efficiencies and bandwidth efficiencies greater than conventional trellis coders with continuous-phase frequency-shift keying (CPFSK).

  4. In-situ SEM indentation studies of the deformation mechanisms in TiN, CrN and TiN/CrN.

    PubMed

    Rzepiejewska-Malyska, K; Parlinska-Wojtan, M; Wasmer, K; Hejduk, K; Michler, J

    2009-01-01

    In this study, the microstructure and the deformation mechanisms of TiN, CrN and multilayer TiN/CrN thin films on silicon substrates were investigated. Cross-sectional lamellas of nanoindents were prepared by focused ion beam milling to observe by transmission electron microscopy the microstructure of the as-deposited and deformed materials. TiN film exhibits nanocrystalline columns, whereas CrN shows large grains. The TiN/CrN multilayer presents microstructural features typical for both materials. A film hardness of 16.9GPa for CrN, 15.8GPa for TiN and 16.6GPa for TiN/CrN was found by the nanoindentation. Reduced modulus recorded for TiN and CrN reference coatings were 221.54 and 171.1GPa, respectively, and 218.6GPa for the multilayer coating. The deformation mechanisms were observed via in-situ scanning electron microscope nanoindentation. The TiN thin film showed short radial cracks, whereas CrN deformed through pile-up and densification of the material. For TiN/CrN multilayer pile-up and cracks were found. Transmission electron microscopy observations indicated that TiN deforms through grain boundary sliding and CrN via densification and material flow. The deformation mechanism observed in TiN/CrN multilayer was found to be a mixture of both modes.

  5. Plasma chemistries for dry etching GaN, AlN, InGaN and InAlN

    SciTech Connect

    Pearton, S.J.; Vartuli, C.B.; Lee, J.W.; Donovan, S.M.; MacKenzie, J.D.; Abernathy, C.R.; Shul, R.J.; McLane, G.F.; Ren, F.

    1996-04-01

    Etch rates up to 7,000 {angstrom}/min. for GaN are obtained in Cl{sub 2}/H{sub 2}/Ar or BCl{sub 3}/Ar ECR discharges at 1--3mTorr and moderate dc biases. Typical rates with HI/H{sub 2} are about a factor of three lower under the same conditions, while CH{sub 4}/H{sub 2} produces maximum rates of only {approximately}2,000 {angstrom}/min. The role of additives such as SF{sub 6}, N{sub 2}, H{sub 2} or Ar to the basic chlorine, bromine, iodine or methane-hydrogen plasma chemistries are discussed. Their effect can be either chemical (in forming volatile products with N) or physical (in breaking bonds or enhancing desorption of the etch products). The nitrides differ from conventional III-V`s in that bond-breaking to allow formation of the etch products is a critical factor. Threshold ion energies for the onset of etching of GaN, InGaN and InAlN are {ge} 75 eV.

  6. Recent research progress on preparation and application of N, N, N-trimethyl chitosan.

    PubMed

    Wu, Meiyan; Long, Zhu; Xiao, Huining; Dong, Cuihua

    2016-11-03

    N,N,N-trimethyl chitosan (TMC) is a quaternized chitosan derivative with excellent solubility in aqueous solutions. It has been extensively studied as an absorption enhancer, antibacterial agent and gene vector due to its ability to form complexes with anionic gels or macromoleculars. However, the research which describes the process of TMC preparation and its new applications has not been fully reviewed. In this paper, recent progress regarding different TMC preparation methods and its characterization and application in different fields is presented. Key findings are compared and summarized and some topics for further study are suggested.

  7. Preparation and cytotoxicity of N,N,N-trimethyl chitosan/alginate beads containing gold nanoparticles.

    PubMed

    Martins, Alessandro F; Facchi, Suelen P; Monteiro, Johny P; Nocchi, Samara R; Silva, Cleiser T P; Nakamura, Celso V; Girotto, Emerson M; Rubira, Adley F; Muniz, Edvani C

    2015-01-01

    Polyelectrolyte complex beads based on N,N,N-trimethyl chitosan (TMC) and sodium alginate (ALG) were obtained. This biomaterial was characterised by FTIR, TGA/DTG, DSC and SEM analysis. The good properties of polyelectrolyte complex hydrogel beads were associated, for the first time, with gold nanoparticles (AuNPs). Through a straightforward methodology, AuNPs were encapsulated into the beads. The in vitro cytotoxicity assays on the Caco-2 colon cancer cells and healthy VERO cells showed that the beads presented good biocompatibility on both cell lines, whereas the beads loaded with gold nanoparticles (beads/AuNPs) was slightly cytotoxic on the Caco-2 and VERO cells.

  8. Enthalpies of formation of gas-phase N3, N3-, N5+, and N5- from Ab initio molecular orbital theory, stability predictions for N5(+)N3(-) and N5(+)N5(-), and experimental evidence for the instability of N5(+)N3(-).

    PubMed

    Dixon, David A; Feller, David; Christe, Karl O; Wilson, William W; Vij, Ashwani; Vij, Vandana; Jenkins, H Donald Brooke; Olson, Ryan M; Gordon, Mark S

    2004-01-28

    Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3-, N5+, and N5- from total atomization energies. The calculated heats of formation of the gas-phase molecules/ions at 0 K are DeltaHf(N3(2Pi)) = 109.2, DeltaHf(N3-(1sigma+)) = 47.4, DeltaHf(N5-(1A1')) = 62.3, and DeltaHf(N5+(1A1)) = 353.3 kcal/mol with an estimated error bar of +/-1 kcal/mol. For comparison purposes, the error in the calculated bond energy for N2 is 0.72 kcal/mol. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, enable reliable stability predictions for the hypothetical N5(+)N3(-) and N5(+)N5(-) salts. The calculations show that neither salt can be stabilized and that both should decompose spontaneously into N3 radicals and N2. This conclusion was experimentally confirmed for the N5(+)N3(-) salt by low-temperature metathetical reactions between N5SbF6 and alkali metal azides in different solvents, resulting in violent reactions with spontaneous nitrogen evolution. It is emphasized that one needs to use adiabatic ionization potentials and electron affinities instead of vertical potentials and affinities for salt stability predictions when the formed radicals are not vibrationally stable. This is the case for the N5 radicals where the energy difference between vertical and adiabatic potentials amounts to about 100 kcal/mol per N5.

  9. SU(N) irreducible Schwinger bosons

    SciTech Connect

    Mathur, Manu; Raychowdhury, Indrakshi; Anishetty, Ramesh

    2010-09-15

    We construct SU(N) irreducible Schwinger bosons satisfying certain U(N-1) constraints which implement the symmetries of SU(N) Young tableaues. As a result all SU(N) irreducible representations are simple monomials of (N-1) types of SU(N) irreducible Schwinger bosons. Further, we show that these representations are free of multiplicity problems. Thus, all SU(N) representations are made as simple as SU(2).

  10. Potential impact of atmospheric N deposition on soil N2O emission varies with different soil N regimes

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Yi, M.; Koike, T.

    2011-12-01

    Future increases in nitrogen (N) deposition has the potential to change belowground nutrient dynamics, especially N cycle, and thereby can alter the soil-atmosphere exchange of nitrous oxide (N2O) which is one of the major greenhouse gases. Moreover, we considered that their effect on soil N2O emission varies with different soil N levels because N2O is a by-product of the biological nitrification process in aerobic soil environments and of the biological denitrification process in anaerobic soil environments. To understand the changes in soil N2O flux under different soil N, we carried out simulated N addition experiment in three-year-old hybrid larch F1 (F1: Larix gmelinii var. japonica × Larix kaempferi) plantation during two growing seasons 2008 - 2009. The hybrid larch F1 was developed to make up for several problems of larch species, e.g. a high susceptibility to disease or grazing damage by insects and fungi, and a large number of this seedlings are planted recently in northern Japan. Based on soil analysis, we selected two sites which have different soil N concentration, i.e. low-N and high-N concentrations. Nitrogen input was initiated at the onset of our experiment, and included four treatments with four replications: Low-N soil + Zero-N control, Low-N soil + 50 kg-N addition, High-N soil + Zero-N control and High-N soil + 50 kg-N addition. The N was added as ammonium nitrate (NH4NO3) solution distributed in four occasions during each growing season. Gas and soil samples were taken from each plot on ten occasions at a time during each growing season. Collected N2O concentrations were determined by a gas chromatograph (GC-14B; Shimadzu, Kyoto, Japan) equipped with an electron capture detector, while total-N and inorganic-N concentrations were obtained by a NC analyzer (Sumigraph NC-1000; Sumica Chemical Analysis Service Ltd., Osaka, Japan) and an auto analyzer (AACS-4; BL-TEC Inc., Osaka, Japan), respectively. Before the N addition, initial total-N in High-N

  11. Enhanced sheet carrier densities in polarization controlled AlInN/AlN/GaN/InGaN field-effect transistor on Si (111)

    SciTech Connect

    Hennig, J. Dadgar, A.; Witte, H.; Bläsing, J.; Lesnik, A.; Strittmatter, A.; Krost, A.

    2015-07-15

    We report on GaN based field-effect transistor (FET) structures exhibiting sheet carrier densities of n = 2.9 10{sup 13} cm{sup −2} for high-power transistor applications. By grading the indium-content of InGaN layers grown prior to a conventional GaN/AlN/AlInN FET structure control of the channel width at the GaN/AlN interface is obtained. The composition of the InGaN layer was graded from nominally x{sub In} = 30 % to pure GaN just below the AlN/AlInN interface. Simulations reveal the impact of the additional InGaN layer on the potential well width which controls the sheet carrier density within the channel region of the devices. Benchmarking the In{sub x}Ga{sub 1−x}N/GaN/AlN/Al{sub 0.87}In{sub 0.13}N based FETs against GaN/AlN/AlInN FET reference structures we found increased maximum current densities of I{sub SD} = 1300 mA/mm (560 mA/mm). In addition, the InGaN layer helps to achieve broader transconductance profiles as well as reduced leakage currents.

  12. Study of singlet oxygen equilibrium in dioctadecyldimethylammonium chloride vesicles employing 2-(n-(N,N,N-trimethylamine)-n-alkyl)-5-alkylfuryl halides.

    PubMed

    Zanocco, Antonio L; Meléndrez, Mónica; Günther, Germán; Lemp, Else

    2007-01-01

    Steady state photolysis and time resolved near infrared luminescence detection were employed to study the reaction kinetics of singlet oxygen with three different lipid-soluble probes incorporated in large unilamellar dioctadecyldimethylammonium chloride (DODAC) vesicles. The probes: 2-(4-(N,N,N-trimethylamine)-butyl)-5-dodecylfuryl bromide (DFTA), 2-(12-(N,N,N-trimethylamine)-dodecyl)-5-hexylfuryl bromide (HFDA) and 2-(1-(N,N,N-trimethylamine)-methyl)-5-methylfuryl iodide (MFMA) are useful in studying both singlet oxygen dynamics and its equilibrium in microcompartmentalized systems because they are actinometers in lipidic microphases. These probes contain a reactive furan ring, which will be located at different depths in the bilayer of DODAC vesicles. In the limit of the approximations, the result indicates an inhomogeneous equilibrium distribution of singlet oxygen across the bilayer. The calculated mean partitioning constant of singlet oxygen equals 2.8 and 8.3 at 20 degrees C and 40 degrees C, respectively, in the order of the previously reported constants for other microorganized systems such as sodium dodecylsulfate and cetyltrimethylammonium halide micelles and water/oil microemulsions.

  13. Metal-Free Functionalization of N,N-Dialkylanilines via Temporary Oxidation to N,N-Dialkylaniline N-Oxides and Group Transfer

    PubMed Central

    2015-01-01

    A simple set of protocols for the controlled elaboration of anilines is reported allowing access to a diverse array of aminophenols, aminoarylsulfonates, alkylated anilines, and aminoanilines in 29–95% yield in a single laboratory operation from easily isolable, bench-stable N,N-dialkylaniline N-oxides. The introduction of new C–O, C–C, and C–N bonds on the aromatic ring is made possible by a temporary increase in oxidation level and excision of a weak N–O bond. PMID:24992642

  14. Anomalous DC and RF behavior of virgin AlGaN/AlN/GaN HEMTs

    NASA Astrophysics Data System (ADS)

    Sánchez-Martín, H.; García-Pérez, Ó.; Pérez, S.; Altuntas, P.; Hoel, V.; Rennesson, S.; Cordier, Y.; González, T.; Mateos, J.; Íñiguez-de-la-Torre, I.

    2017-03-01

    The performance of gallium nitride transistors is still limited by technological problems often related to defects and traps. In this work, virgin AlGaN/AlN/GaN HEMTs exhibiting an anomalous DC behavior accompanied by frequency dispersion in the microwave range, both in the transconductance and output conductance, are analyzed. This anomalous response, which is mitigated by high-bias conditions, is attributed to the presence of traps and defects both in the volume of the GaN channel and in the source and drain contacts. A simple equivalent circuit model is proposed to replicate the dispersive response of the transistor, achieving an excellent agreement with the measured S–parameters and thus providing relevant information about its characteristic frequency.

  15. Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

    NASA Astrophysics Data System (ADS)

    Yan, Xiaodong; Li, Wenjun; Islam, S. M.; Pourang, Kasra; Xing, Huili Grace; Fay, Patrick; Jena, Debdeep

    2015-10-01

    By the insertion of thin InxGa1-xN layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors.

  16. Thermophysical properties of N, N-dimethylacetamide mixtures with n-butanol

    NASA Astrophysics Data System (ADS)

    Maharolkar, Aruna P.; Murugkar, A. G.; Khirade, P. W.; Mehrotra, S. C.

    2017-09-01

    The refraction, dielectric, viscosity, density, data of the binary mixtures of N, N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature.

  17. Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

    SciTech Connect

    Yan, Xiaodong; Li, Wenjun; Islam, S. M.; Pourang, Kasra; Fay, Patrick; Xing, Huili; Jena, Debdeep

    2015-10-19

    By the insertion of thin In{sub x}Ga{sub 1−x}N layers into Nitrogen-polar GaN p-n junctions, polarization-induced Zener tunnel junctions are studied. The reverse-bias interband Zener tunneling current is found to be weakly temperature dependent, as opposed to the strongly temperature-dependent forward bias current. This indicates tunneling as the primary reverse-bias current transport mechanism. The Indium composition in the InGaN layer is systematically varied to demonstrate the increase in the interband tunneling current. Comparing the experimentally measured tunneling currents to a model helps identify the specific challenges in potentially taking such junctions towards nitride-based polarization-induced tunneling field-effect transistors.

  18. GaN-based ultraviolet light-emitting diodes with AlN/GaN/InGaN multiple quantum wells.

    PubMed

    Chang, Hung-Ming; Lai, Wei-Chih; Chen, Wei-Shou; Chang, Shoou-Jinn

    2015-04-06

    We demonstrate indium gallium nitride/gallium nitride/aluminum nitride (AlN/GaN/InGaN) multi-quantum-well (MQW) ultraviolet (UV) light-emitting diodes (LEDs) to improve light output power. Similar to conventional UV LEDs with AlGaN/InGaN MQWs, UV LEDs with AlN/GaN/InGaN MQWs have forward voltages (V(f)'s) ranging from 3.21 V to 3.29 V at 350 mA. Each emission peak wavelength of AlN/GaN/InGaN MQW UV LEDs presents 350 mA output power greater than that of the corresponding emission peak wavelength of AlGaN/InGaN MQW UV LEDs. The light output power at 350mA of AlN/GaN/InGaN MQWs UV LEDs with 375 nm emission wavelength can reach around 26.7% light output power enhancement in magnitude compared to the AlGaN/InGaN MQWs UV LEDs with same emission wavelength. But 350mA light output power of AlN/GaN/InGaN MQWs UV LEDs with emission wavelength of 395nm could only have light output power enhancement of 2.43% in magnitude compared with the same emission wavelength AlGaN/InGaN MQWs UV LEDs. Moreover, AlN/GaN/InGaN MQWs present better InGaN thickness uniformity, well/barrier interface quality and less large size pits than AlGaN/InGaN MQWs, causing AlN/GaN/InGaN MQW UV LEDs to have less reverse leakage currents at -20 V. Furthermore, AlN/GaN/InGaN MQW UV LEDs have the 2-kV human body mode (HBM) electrostatic discharge (ESD) pass yield of 85%, which is 15% more than the 2-kV HBM ESD pass yield of AlGaN/InGaN MQW UV LEDs of 70%.

  19. Sturmian function approach and {bar N}N bound states

    SciTech Connect

    Yan, Y.; Tegen, R.; Gutsche, T.; Faessler, A.

    1997-09-01

    A suitable numerical approach based on Sturmian functions is employed to solve the {bar N}N bound state problem for local and nonlocal potentials. The approach accounts for both the strong short-range nuclear potential and the long-range Coulomb force and provides directly the wave function of protonium and {bar N}N deep bound states with complex eigenvalues E=E{sub R}{minus}i({Gamma}/2). The spectrum of {bar N}N bound states has two parts, the atomic states bound by several keV, and the deep bound states which are bound by several hundred MeV. The observed very small hyperfine splitting of the 1s level and the 1s and 2p decay widths are reasonably well reproduced by both the Paris and Bonn potentials (supplemented with a microscopically derived quark annihilation potential), although there are differences in magnitude and level ordering. We present further arguments for the identification of the {sup 13}PF{sub 2} deep bound state with the exotic tensor meson f{sub 2}(1520). Both investigated models can accommodate the f{sub 2}(1520) but differ greatly in the total number of levels and in their ordering. The model based on the Paris potential predicts the {sup 13}P{sub 0} level slightly below 1.1 GeV while the model based on the Bonn potential puts this state below 0.8 GeV. It remains to be seen if this state can be identified with a scalar partner of the f{sub 2}(1520). {copyright} {ital 1997} {ital The American Physical Society}

  20. Diffusion technique for 15N and inorganic N analysis of low-N aqueous solutions and Kjeldahl digests.

    PubMed

    Chen, Rui Rui; Dittert, Klaus

    2008-06-01

    Diffusion of ammonia is a common sample preparation method for the stable isotope analysis of inorganic nitrogen in aqueous solution. Classical diffusion methods usually require 6-12 days of diffusion and often focus on (15)N/(14)N analysis only. More recent studies have discussed whether complete N recovery was necessary for the precise analysis of stable N isotope ratios. In this paper we present a newly revised diffusion technique that allows correct and simultaneous determination of total N and (15)N at% from aqueous solutions and Kjeldahl digests, with N concentrations down to sub-0.5-mg N L(-1) levels, and it is tested under different conditions of (15)N isotope labelling. With the modification described, the diffusion time was reduced to 72 h, while the ratios of measured and expected (15)N at% were greater than 99% and the simultaneous recovery of total N was >95%. Analysis of soil microbial biomass N and its (15)N/(14)N ratio is one of the most important applications of this diffusion technique. An experiment with soil extracts spiked with (15)N-labelled yeast showed that predigestion was necessary to prevent serious N loss during Kjeldahl digestion of aqueous samples (i.e. soil extracts). The whole method of soil microbial biomass N preparation for (15)N/(14)N analysis included chloroform fumigation, predigestion, Kjeldahl digestion and diffusion. An experiment with soil spiked with (15)N-labelled yeast was carried out to evaluate the method. Results showed a highly significant correlation of recovered and added N, with the same recovery rate (0.21) of both total N and (15)N. A k(N) value of 0.25 was obtained based on the data. In conclusion, the diffusion method works for soil extracts and microbial biomass N determination and hence could be useful in many types of soil/water studies.

  1. Low temperature properties of spin filter NbN/GdN/NbN Josephson junctions

    NASA Astrophysics Data System (ADS)

    Massarotti, D.; Caruso, R.; Pal, A.; Rotoli, G.; Longobardi, L.; Pepe, G. P.; Blamire, M. G.; Tafuri, F.

    2017-02-01

    A ferromagnetic Josephson junction (JJ) represents a special class of hybrid system where different ordered phases meet and generate novel physics. In this work we report on the transport measurements of underdamped ferromagnetic NbN/GdN/NbN JJs at low temperatures. In these junctions the ferromagnetic insulator gadolinium nitride barrier generates spin-filtering properties and a dominant second harmonic component in the current-phase relation. These features make spin filter junctions quite interesting also in terms of fundamental studies on phase dynamics and dissipation. We discuss the fingerprints of spin filter JJs, through complementary transport measurements, and their implications on the phase dynamics, through standard measurements of switching current distributions. NbN/GdN/NbN JJs, where spin filter properties can be controllably tuned along with the critical current density (Jc), turn to be a very relevant term of reference to understand phase dynamics and dissipation in an enlarged class of JJs, not necessarily falling in the standard tunnel limit characterized by low Jc values.

  2. New data on ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stepanov, M. E.

    2013-11-15

    Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F{sub i} = {sigma}({gamma}, in)/{sigma}({gamma}, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F{sub 2} > 0.50 for a vast body of data). New data on the cross sections for partial reactions on {sup 181}Ta and {sup 208}Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section {sigma}{sup expt}({gamma}, xn) = {sigma}({gamma}, n) + 2{sigma}({gamma}, 2n) + 3{sigma}({gamma}, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F{sub i}{sup theor} calculated within a combined model of photonuclear reactions.

  3. Theoretical and experimental studies of electric field distribution in N-polar GaN/AlGaN/GaN heterostructures

    SciTech Connect

    Gladysiewicz, M. Janicki, L.; Kudrawiec, R.; Siekacz, M.; Cywinski, G.

    2015-12-28

    Electric field distribution in N-polar GaN(channel)/AlGaN/GaN(buffer) heterostructures was studied theoretically by solving Schrodinger and Poisson equations in a self-consistent manner for various boundary conditions and comparing results of these calculations with experimental data, i.e., measurements of electric field in GaN(channel) and AlGaN layers by electromodulation spectroscopy. A very good agreement between theoretical calculations and experimental data has been found for the Fermi-level located at ∼0.3 eV below the conduction band at N-polar GaN surface. With this surface boundary condition, the electric field distribution and two dimensional electron gas concentration are determined for GaN(channel)/AlGaN/GaN(buffer) heterostructures of various thicknesses of GaN(channel) and AlGaN layers.

  4. Performance characteristics of magnesium— N,N'-dichlorodimethylhydantoin primary cell

    NASA Astrophysics Data System (ADS)

    Udhayan, R.; Muniyandi, N.; Mathur, P. B.

    The electrochemical characteristics of cells using N,N'-dichlorodimethylhydantoin (DDH) as a cathode depolarizer and magnesium anodes are reported. The discharge behaviour of DDH gives high cathode potential and efficiency. The discharge data are fitted to a general equation to express the voltage/current features of the system. Cyclic voltammograms of DDH in neutral electrolytes substantiate the claimed reduction behaviour. Magnesium bromide solution provides higher capacities than Mg(ClO 4) 2 but corrosion of the magnesium anode is more severe in the former electrolyte.

  5. 6-Propionyl-2-(N,N-dimethylamino) naphthalene (PRODAN) revisited

    SciTech Connect

    Sun, S. |; Heitz, M.P.; Perez, S.A.; Colon, L.A.; Bruckenstein, S.; Bright, F.V.

    1997-09-01

    The photophysics of 6-propionyl-2-(N,N-dimethylamino) naphthalene (PRODAN) in liquid water are reported. Our results demonstrate that the often mentioned extra blue-edge shoulder seen for PRODAN in liquid water is a result of PRODAN-PRODAN intermolecular interactions in a supersaturated PRODAN solution and not a consequence of impurities in the commercial PRODAN preparations. In all cases where the aqueous PRODAN solution is not supersaturated, there is no detectable blue-edge emission shoulder. {copyright} {ital 1997} {ital Society for Applied Spectroscopy}

  6. BOC(n,n) signal multipath mitigation using MEDLL technology

    NASA Astrophysics Data System (ADS)

    Su, Xuan; Zhang, Yanmei; Su, Lianqing; Guo, Haichao

    2015-11-01

    For satellite navigation and positioning receivers are susceptible to the influence of the multipath, this paper used multipath estimating delay lock loop (MEDLL) technology for BOC (n, n) multipath signal tracking. Through the analysis of multipath signal model, it is concluded that all the multipath signal can be expressed by its amplitude, phase and delay. Then in odor to get the accurate direct signal, this paper applied MEDLL algorithm to estimate the received signal. Finally, the simulation show that this algorithm can realize multipath signal track demodulation and accurate data demodulation under a low signal noise ratio environment (SNR= -20db).

  7. Photodissociation dynamics of IBr(-)(CO(2))(n), n<15.

    PubMed

    Sanford, Todd; Han, Sang-Yun; Thompson, Matthew A; Parson, Robert; Lineberger, W Carl

    2005-02-01

    We report the ionic photoproducts produced following photoexcitation of mass selected IBr(-)(CO(2))(n), n=0-14, cluster ions at 790 and 355 nm. These wavelengths provide single state excitation to two dissociative states, corresponding to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states of the IBr(-) chromophore. Excitation of these states in IBr(-) leads to production of I(-)+Br and Br(-)+I( *), respectively. Potential energy curves for the six lowest electronic states of IBr(-) are calculated, together with structures for IBr(-)(CO(2))(n), n=1-14. Translational energy release measurements on photodissociated IBr(-) determine the I-Br(-) bond strength to be 1.10+/-0.04 eV; related measurements characterize the A(') (2)Pi(1/2)<--X (2)Sigma(1/2) (+) absorption band. Photodissociation product distributions are measured as a function of cluster size following excitation to the A(') (2)Pi(1/2) and B 2 (2)Sigma(1/2) (+) states. The solvent is shown to drive processes such as spin-orbit relaxation, charge transfer, recombination, and vibrational relaxation on the ground electronic state. Following excitation to the A(') (2)Pi(1/2) electronic state, IBr(-)(CO(2))(n) exhibits size-dependent cage fractions remarkably similar to those observed for I(2) (-)(CO(2))(n). In contrast, excitation to the B 2 (2)Sigma(1/2) (+) state shows extensive trapping in excited states that dominates the recombination behavior for all cluster sizes we investigated. Finally, a pump-probe experiment on IBr(-)(CO(2))(8) determines the time required for recombination on the ground state following excitation to the A(') state. While the photofragmentation experiments establish 100% recombination in the ground electronic state for this and larger IBr(-) cluster ions, the time required for recombination is found to be approximately 5 ns, some three orders of magnitude longer than observed for the analogous I(2) (-) cluster ion. Comparisons are made with similar experiments carried out on I(2

  8. N,N-dimethylformamide: a multipurpose building block.

    PubMed

    Ding, Shengtao; Jiao, Ning

    2012-09-10

    Often used as a common solvent for chemical reations and utilized widely in industry as a reagent, N,N-dimethylformamide (DMF) has played an important role in organic synthesis for a long time. Numerous highly useful articles and reviews discussing its utilizations have been published. With a focus on the performance of DMF as a multipurpose precursor for various units in numerous reactions, this Minireview summarizes recent developments in the employment of DMF in the fields of formylation, aminocarbonylation, amination, amidation, and cyanation, as well as its reaction with arynes.

  9. Hepatic microsomal N-oxidation and N-demethylation of N,N-dimethylaniline in red-winged blackbird compared with rat and other birds

    USGS Publications Warehouse

    Pan, H.P.; Fouts, J.R.; Devereux, T.R.

    1975-01-01

    Hepatic microsomes prepared from red-winged blackbirds and albino rats were incubated with N,N-dimethylaniline (DMA)_in complete incubation mixtures at pH 7.9 and 37?C for 10 min. Formaldehyde and N,N-dimethylaniline--oxide produced from DMA were measured. Redwings were found to have significantly lower N-demethylation activities than rats, and redwings had only marginal or no N-oxidation activities. Hepatic microsomes from redwings did not further metabolize the N-oxide. The N-oxidation and N-demethylation activities of brown-headed cowbirds, common grackles, and starlings were similar to those of redwings.

  10. Photodissociation of interstellar N2

    NASA Astrophysics Data System (ADS)

    Li, X.; Heays, A. N.; Visser, R.; Ubachs, W.; Lewis, B. R.; Gibson, S. T.; van Dishoeck, E. F.

    2013-07-01

    Context. Molecular nitrogen is one of the key species in the chemistry of interstellar clouds and protoplanetary disks, but its photodissociation under interstellar conditions has never been properly studied. The partitioning of nitrogen between N and N2 controls the formation of more complex prebiotic nitrogen-containing species. Aims: The aim of this work is to gain a better understanding of the interstellar N2 photodissociation processes based on recent detailed theoretical and experimental work and to provide accurate rates for use in chemical models. Methods: We used an approach similar to that adopted for CO in which we simulated the full high-resolution line-by-line absorption + dissociation spectrum of N2 over the relevant 912-1000 Å wavelength range, by using a quantum-mechanical model which solves the coupled-channels Schrödinger equation. The simulated N2 spectra were compared with the absorption spectra of H2, H, CO, and dust to compute photodissociation rates in various radiation fields and shielding functions. The effects of the new rates in interstellar cloud models were illustrated for diffuse and translucent clouds, a dense photon dominated region and a protoplanetary disk. Results: The unattenuated photodissociation rate in the Draine (1978, ApJS, 36, 595) radiation field assuming an N2 excitation temperature of 50 K is 1.65 × 10-10 s-1, with an uncertainty of only 10%. Most of the photodissociation occurs through bands in the 957-980 Å range. The N2 rate depends slightly on the temperature through the variation of predissociation probabilities with rotational quantum number for some bands. Shielding functions are provided for a range of H2 and H column densities, with H2 being much more effective than H in reducing the N2 rate inside a cloud. Shielding by CO is not effective. The new rates are 28% lower than the previously recommended values. Nevertheless, diffuse cloud models still fail to reproduce the possible detection of interstellar N2

  11. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10193 1-Butanaminium, N-(3...

  12. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10193 1-Butanaminium, N-(3...

  13. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10193 1-Butanaminium, N-(3...

  14. GaN High Power Devices

    SciTech Connect

    PEARTON,S.J.; REN,F.; ZHANG,A.P.; DANG,G.; CAO,X.A.; LEE,K.P.; CHO,H.; GILA,B.P.; JOHNSON,J.W.; MONIER,C.; ABERNATHY,C.R.; HAN,JUNG; BACA,ALBERT G.; CHYI,J.-I.; LEE,C.-M.; NEE,T.-E.; CHUO,C.-C.; CHI,G.C.; CHU,S.N.G.

    2000-07-17

    A brief review is given of recent progress in fabrication of high voltage GaN and AlGaN rectifiers, GaN/AlGaN heterojunction bipolar transistors, GaN heterostructure and metal-oxide semiconductor field effect transistors. Improvements in epitaxial layer quality and in fabrication techniques have led to significant advances in device performance.

  15. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10193 1-Butanaminium, N-(3...

  16. Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High Electron Mobility Transistors

    DTIC Science & Technology

    2016-06-07

    microscopy (TEM) studies reveal that the GaN/ AlN/AlGaN radial nanowire heterostructures are dislocation -free single crystals. In addition, the...due to a reduction or elimination of impurity scattering by separating the dopants and surface potential fluctuations from the conduction channel . We...AlN/AlGaN radial nanowire heterostructures are dislocation -free single crystals. In addition, the thicknesses and compositions of the individual AlN

  17. nEDM at SNS

    SciTech Connect

    Clayton, Steven

    2014-07-30

    This PowerPoint presentation covered the following topics: Overview; participants in the collaboration; the experimental method and Free Precession Method descriptions; and then experimental design elements, ending with a summary. A new nEDM experiment is under development with a goal sensitivity 90% CL σd < (3-5) x 10-28 e-cm in 300 live-days; Free precession method: SQUIDS to read out the 3He precession frequency, Scintillation signal for the n relative precession frequency; Dressed spin method: Strong RF field to match n and 3He effective magnetic moments; Modulation/feedback of dressing parameter based on scintillation signal; and, Ongoing development/demonstration of many aspects of the apparatus (a subset was shown here).

  18. N-(Diphenylselenio)diphenylsulfimidium tetraphenylborate.

    PubMed

    Aucott, Stephen M; Dale, Sophie H; Elsegood, Mark R J; Gilby, Liam M; Holmes, Kathryn E; Kelly, Paul F

    2005-02-01

    The title compound, C24H20NSSe+.C24H20B-, exhibits disorder (S/Se scrambling) of the chalcogen sites within the S-N-Se triad. Similar disorder was observed in the bromide salt [Aucott, Bailey, Elsegood, Gilby, Holmes, Kelly, Papageorgiou & Pedron-Haba (2004). New J. Chem. pp. 959-966]. The S-N and Se-N bond lengths are 1.6735 (15) and 1.8045 (14) A, respectively. Whereas the chalcogens in the bromide salt are involved in S...Br and Se...Br interactions of very similar distances, the scrambled S and Se sites in the title compound are involved in distinct non-bonded interactions. The site predominantly occupied by sulfur is involved in C-H...S/Se interactions, while the site predominantly occupied by selenium is involved in Se/S...pi interactions.

  19. The N=2 superconformal bootstrap

    NASA Astrophysics Data System (ADS)

    Beem, Christopher; Lemos, Madalena; Liendo, Pedro; Rastelli, Leonardo; van Rees, Balt C.

    2016-03-01

    In this work we initiate the conformal bootstrap program for N=2 super-conformal field theories in four dimensions. We promote an abstract operator-algebraic viewpoint in order to unify the description of Lagrangian and non-Lagrangian theories, and formulate various conjectures concerning the landscape of theories. We analyze in detail the four-point functions of flavor symmetry current multiplets and of N=2 chiral operators. For both correlation functions we review the solution of the superconformal Ward identities and describe their superconformal block decompositions. This provides the foundation for an extensive numerical analysis discussed in the second half of the paper. We find a large number of constraints for operator dimensions, OPE coefficients, and central charges that must hold for any N=2 superconformal field theory.

  20. Bubble dynamics in N dimensions

    NASA Astrophysics Data System (ADS)

    Klotz, Alexander R.

    2013-08-01

    Cavitation and bubble dynamics are central concepts in engineering, the natural sciences, and the mathematics of fluid mechanics. Due to the nonlinear nature of their dynamics, the governing equations are not fully solvable. Here, the dynamics of a spherical bubble in an N-dimensional fluid are discussed in the hope that examining bubble behavior in N dimensions will add insight to their behavior in three dimensions. Several canonical results in bubble dynamics are re-derived, including the Rayleigh collapse time, the Rayleigh-Plesset equation, and the Minnaert frequency. Recent analytical approximations to the Rayleigh collapse are discussed, and the N-dimensional generalization is used to resolve a known discrepancy. Numerical simulations are used to examine the onset of nonlinear behavior. Overall, the dynamics of bubbles are faster at higher dimensions, with nonlinear behavior occurring at lower strain. Several features are found to be unique to three dimensions, including the trend of nonlinear behavior and apparent coincidences in timescales.

  1. Experimental observation of N00N state Bloch oscillations

    PubMed Central

    Lebugle, Maxime; Gräfe, Markus; Heilmann, René; Perez-Leija, Armando; Nolte, Stefan; Szameit, Alexander

    2015-01-01

    Bloch oscillations of quantum particles manifest themselves as periodic spreading and relocalization of the associated wave functions when traversing lattice potentials subject to external gradient forces. Albeit this phenomenon is deeply rooted into the very foundations of quantum mechanics, all experimental observations so far have only contemplated dynamics of one and two particles initially prepared in separable local states. Evidently, a more general description of genuinely quantum Bloch oscillations will be achieved on excitation of a Bloch oscillator by nonlocal states. Here we report the observation of Bloch oscillations of two-particle N00N states, and discuss the nonlocality on the ground of Bell-like inequalities. The time evolution of two-photon N00N states in Bloch oscillators, whether symmetric, antisymmetric or partially symmetric, reveals transitions from particle antibunching to bunching. Consequently, the initial states can be tailored to produce spatial correlations akin to those of bosons, fermions and anyons, presenting potential applications in photonic quantum simulation. PMID:26391683

  2. Extent of shielding by counterions determines the bactericidal activity of N,N,N-trimethyl chitosan salts.

    PubMed

    Follmann, Heveline D M; Martins, Alessandro F; Nobre, Thatyane M; Bresolin, Joana D; Cellet, Thelma S P; Valderrama, Patrícia; Correa, Daniel S; Muniz, Edvani C; Oliveira, Osvaldo N

    2016-02-10

    In this study, we show that the bactericidal activity of quaternized chitosans (TMCs) with sulfate, acetate, and halide counterions against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) correlates with the "availability" of N-quaternized groups [-(+)N(CH3)3] in the TMCs backbones. N,N,N-trimethyl chitosan sulfate (TMCS) and N,N,N-trimethyl chitosan acetate (TMCAc) displayed the highest activities, probably due to their delocalized π system. Among TMCs with halide counterions, activity was higher for N,N,N-trimethyl chitosan chloride (TMCCl), whereas N,N,N-trimethyl chitosan iodide (TMCI) and N,N,N-trimethyl chitosan bromide (TMCBr) exhibited lower, similar values to each other. This is consistent with the shielding of -(+)N(CH3)3 groups inferred from chemical shifts for halide counterions in (1)HNMR spectra. We also demonstrate that TMCs with distinct bactericidal activities can be classified according to their vibrational spectra using principal component analysis. Taken together, these physicochemical characterization approaches represent a predictive tool for the bactericidal activity of chitosan derivatives.

  3. AlGaN/AlN-GaN-SL HEMTs with Multiple 2DEG Channels

    NASA Astrophysics Data System (ADS)

    Wille, Ada; Yacoub, Hady; Debald, Arne; Kalisch, Holger; Vescan, Andrei

    2015-05-01

    We report on a multichannel approach for AlGaN/GaN high-electron-mobility transistors (HEMTs) to increase the carrier mobility in the low and high sheet carrier concentration regimes. Between the AlGaN barrier and GaN buffer, alternating thin layers of AlN and GaN were inserted to create multiple two-dimensional electron gas (2DEG) channels. All samples were grown by metalorganic vapor-phase epitaxy (MOVPE) on sapphire substrates and compared with conventional single-channel HEMT with the same sheet carrier concentration. For low total 2DEG carrier concentrations (<8 × 1012 cm-2), the mobility for the multichannel HEMT was enhanced due to a reduction of ionized impurity and dislocation scattering, which originates from a backbarrier effect of the underlying AlN layers. In the high total carrier concentration regime (>8 × 1012 cm-2), a mobility improvement is attributed to distribution of the sheet charge into multiple 2DEG channels. This has been found to reduce the carrier concentration per individual channel, which leads to larger distance between 2DEG and heterointerfaces and therefore less impact of interface roughness and alloy scattering. With increasing number of channels, phonon scattering is also reduced due to lowering of the three-dimensional (3D) electron density, which results from the added volume of the multiple 2DEGs. With this approach, the HEMT mobility was increased from 1620 cm2 V-1 s-1 to 1960 cm2 V-1 s-1 for a triple-channel device at sheet carrier concentration of 7.5 × 1012 cm-2.

  4. Role of nanoscale AlN and InN for the microwave characteristics of AlGaN/(Al,In)N/GaN-based HEMT

    SciTech Connect

    Lenka, T. R. Panda, A. K.

    2011-09-15

    A new AlGaN/GaN-based high electron mobility transistor (HEMT) is proposed and its micro-wave characteristics are discussed by introducing a nanoscale AlN or InN layer to study the potential improvement in their high frequency performance. The 2DEG transport mechanism including various sub-band calculations for both (Al,In) N-based HEMTs are also discussed in the paper. Apart from direct current characteristics of the proposed HEMT, various microwave parameters such as transconductance, unit current gain (h{sub 21} = 1) cut-off frequency (f{sub t}), high power-gain frequency (f{sub max}). Masons available/stable gain and masons unilateral gain are also discussed for both devices to understand its suitable deployment in microwave frequency range.

  5. High-n immersion lithography

    NASA Astrophysics Data System (ADS)

    Sewell, Harry; Mulkens, Jan; Graeupner, Paul; McCafferty, Diane; Markoya, Louis; Donders, Sjoerd; Cortie, Rogier; Meijers, Ralph; Evangelista, Fabrizio; Samarakone, Nandarisi

    2008-03-01

    A two-year study on the feasibility of High-n Immersion Lithography shows very promising results. This paper reports the findings of the study. The evaluation shows the tremendous progress made in the development of second-generation immersion fluid technology. Candidate fluids from several suppliers have been evaluated. All the commercial fluids evaluated are viable, so there are a number of options. Life tests have been conducted on bench top fluid-handling systems and the results referenced to full-scale systems. Parameters such as Dose per Laser Pulse, Pulse Rate, Fluid Flow Rate, and Fluid Absorbency at 193nm, and Oxygen/Air Contamination Levels were explored. A detailed evaluation of phenomena such as Last Lens Element (LLE) contamination has been conducted. Lens cleaning has been evaluated. A comparison of High-n fluid-based technology and water-based immersion technology shows interesting advantages of High-n fluid in the areas of Defect and Resist Interaction. Droplet Drying tests, Resist Staining evaluations, and Resist Contrast impact studies have all been run. Defect-generating mechanisms have been identified and are being eliminated. The lower evaporation rate of the High-n fluids compared with water shows the advantages of High-n Immersion. The core issue for the technology, the availability of High-n optical material for use as the final lens element, is updated. Samples of LuAG material have been received from development partners and have been evaluated. The latest status of optical materials and the technology timelines are reported. The potential impact of the availability of the technology is discussed. Synergy with technologies such as Double Patterning is discussed. The prospects for <22nm (hp) are evaluated.

  6. N-Terminal Methionine Processing.

    PubMed

    Wingfield, Paul T

    2017-04-03

    Protein synthesis is initiated by methionine in eukaryotes and by formylmethionine in prokaryotes. N-terminal methionine can be co-translationally cleaved by the enzyme methionine aminopeptidase (MAP). When recombinant proteins are expressed in bacterial and mammalian expression systems, there is a simple universal rule that predicts whether the initiating methionine will be processed by MAP based on the size of the residue adjacent (penultimate) to the N-methionine. In general, if the side chains of the penultimate residues have a radius of gyration of 1.29 Å or less, methionine is cleaved. © 2017 by John Wiley & Sons, Inc.

  7. Dual Infection of Novel Influenza Viruses A/H1N1 and A/H3N2 in a Cluster of Cambodian Patients

    DTIC Science & Technology

    2011-01-01

    Vomiting N N Y Y N Rhinorrhea N N N N Y Medication Amoxicillin and paracetamol Amoxicillin and paracetamol Amoxicillin and paracetamol Amoxicillin and... paracetamol N Epidemiology Recent travel Within country N N N N Animal exposure N N N N N Disposition Recovered Recovered Recovered Recovered

  8. Influence of Initial Organic N Reserves and Residual Leaf Area on Growth, N Uptake, N Partitioning and N Storage in Alfalfa (Medicago sativa) during Post-cutting Regrowth

    PubMed Central

    MEURIOT, F.; AVICE, J.-C.; SIMON, J.-C.; LAINE, P.; DECAU, M.-L.; OURRY, A.

    2004-01-01

    • Background and Aims The influence of initial residual leaf area and initial N reserves on N uptake, final N distribution, and yield in alfalfa regrowing after cutting, were studied. • Methods The effects of two levels of initial residual leaf area (plants cut to 15 cm, with (L+) or without (L−) their leaves) and two initial levels of N status [high N (HN) or low N (LN)] on growth, N uptake and N partitioning, allocation and storage after 29 d of post-cutting regrowth were analysed. • Key Results During most of the regrowth period (8–29 d after the initial harvest), HN and L+ plants had higher net N uptake rates than LN and L− plants, respectively, resulting in a greater final mineral N uptake for these treatments. However, the final partitioning of exogenous N to the regrowing shoots was the same for all treatments (67 % of total exogenous N on average). Final shoot growth, total plant N content, and N allocation to the different taproot N pools were significantly lower in plants with reduced initial leaf area and initial N reserve status. • Conclusions Although both initial residual leaf area and initial N reserves influenced alfalfa regrowth, the residual leaf area had a greater effect on final forage production and N composition in the taproot, whereas the N uptake rate and final total N content in plant were more affected by the initial N reserve status than by the residual leaf area. Moreover, N storage as proteins (especially as vegetative storage proteins, rather than nitrate or amino acids) in the taproot allowed nitrate uptake to occur at significant rates. This suggests that protein storage is not only a means of sequestering N in a tissue for further mobilization, utilization for growth or tissue maintenance, but may also indirectly influence both N acquisition and reduction capacities. PMID:15271775

  9. Diffusion behavior of dual capping layers in TiN/LaN/AlN/HfSiOx/Si stack

    NASA Astrophysics Data System (ADS)

    Zheng, X. H.; Huang, A. P.; Xiao, Z. S.; Wang, M.; Liu, X. Y.; Wu, Z. W.; Chu, Paul K.

    2011-09-01

    The diffusion behavior and interlayer interactions in the LaN/AlN dual capping layers of TiN/LaN/AlN/HfSiOx/Si stacks are investigated. Depth profiling and chemical state analysis performed after partial removal of the TiN gate indicate that Al-O replaces Al-N forming an Al-O dipole layer between the TiN and high-k layer after annealing. Meanwhile, La diffuses into HfSiOx and the La-based dipole is controlled by suppression of O diffusion to the bottom layer. Our results reveal that the properties of the TiN/LaN/AlN/HfSiOx/Si stack can be improved significantly by the dual capping layers.

  10. Characterization of the N-deacetylase domain from the heparan sulfate N-deacetylase/N-sulfotransferase 2

    SciTech Connect

    Duncan, Michael B.; Liu, May; Fox, Courtney; Liu, Jian . E-mail: jian_liu@unc.edu

    2006-01-27

    Heparin and heparan sulfate are linear sulfated polysaccharides that exert a multitude of biological functions. Heparan sulfate glucosaminyl N-deacetylase/N-sulfotransferase isoform 2 (NDST-2), a key enzyme in the biosynthesis of heparin, contains two distinct activities. This bifunctional enzyme removes the acetyl group from N-acetylated glucosamine (N-deacetylase activity) and transfers a sulfuryl group to the unsubstituted amino position (N-sulfotransferase activity). The N-sulfotransferase activity of NDST has been unambiguously localized to the C-terminal domain of NDST. Here, we report that the N-terminal domain of NDST-2 retains N-deacetylase activity. The N-terminal domain (A66-P604) of human NDST-2, designated as N-deacetylase (NDase), was cloned as a (His){sub 6}-fusion protein, and protein expression was carried out in Escherichia coli. Heparosan treated with NDase contains N-unsubstituted glucosamine and is highly susceptible to N-sulfation by N-sulfotransferase. Our results conclude that the N-terminal domain of NDST-2 contains functional N-deacetylase activity. This finding helps further elucidate the mechanism of action of heparan sulfate N-deacetylase/N-sulfotransferases and the biosynthesis of heparan sulfate in general.

  11. Influence of N2 partial pressure on structural and microhardness properties of TiN/ZrN multilayers deposited by Ar/N2 vacuum arc discharge

    NASA Astrophysics Data System (ADS)

    Naddaf, M.; Abdallah, B.; Ahmad, M.; A-Kharroub, M.

    2016-08-01

    The influence of N2 partial pressure on structural, mechanical and wetting properties of multilayered TiN/ZrN thin films deposited on silicon substrates by vacuum arc discharge of (N2 + Ar) gas mixtures is investigated. X-ray diffraction (XRD) results show that the average texturing coefficient of (1 1 1) orientation and the grain size of both TiN and ZrN individual layers increase with increasing the N2 partial pressure. The Rutherford back scattering (RBS) measurements and analysis reveal that incorporation of the nitrogen in the film increases with increasing the N2 partial pressure and both TiN and ZrN individual layers have a nitrogen over-stoichiometry for N2 partial pressure ⩾50%. The change in the film micro-hardness is correlated to the changes in crystallographic texture, grain size, stoichiometry and the residual stress in the film as a function of the N2 partial pressure. In particular, stoichiometry of ZrN and TiN individual is found to play the vital role in determining the multilayer hardness. The multilayer film deposited at N2 partial pressure of 25% has the best stoichiometric ratio of both TiN and ZrN layers and the highest micro-hardness of about 32 GPa. In addition, water contact angle (WCA) measurements and analysis show a decrease in the work of adhesion on increasing the N2 partial pressure.

  12. Interface states at the SiN/AlGaN interface on GaN heterojunctions for Ga and N-polar material

    NASA Astrophysics Data System (ADS)

    Yeluri, Ramya; Swenson, Brian L.; Mishra, Umesh K.

    2012-02-01

    Dielectric passivation is important to improve the stability and reliability of gallium nitride based semiconductor devices. We need to characterize various dielectrics and their interfaces to nitrides accurately to be able to exploit the benefits efficiently. Earlier, B. L. Swenson and U. K. Mishra [J. Appl. Phys. 106, 064902 (2009)] have detailed a photo-assisted high frequency CV characterization technique for the Ga-polar SiN/GaN interface that gives an accurate value of interface state density (Dit) across the bandgap of the dielectric. In this work, we extend the technique to study the interface states at the SiN/AlGaN interface on GaN for Ga and N polar material. This simulates the AlGaN/GaN HEMT structure. A MIS-type structure comprised of a metal on SiN on an AlGaN/GaN heterojunction was used for the study. For a structure with 1 nm AlGaN interlayer, a peak interface state density of 2.8 × 1012 cm-2 eV-1 was measured. For Ga polar devices, the measured Dit decreases with increasing AlGaN thickness. In the N-polar case, the measured Dit increases with increasing AlGaN thickness. The variations of measured Dit with AlGaN thickness, in both cases, can be explained by screening from the accumulation charge at the AlGaN/GaN interface.

  13. Biomaterials based on N,N,N-trimethyl chitosan fibers in wound dressing applications.

    PubMed

    Zhou, Zhongzheng; Yan, Dong; Cheng, Xiaojie; Kong, Ming; Liu, Ya; Feng, Chao; Chen, Xiguang

    2016-08-01

    In the present work, N,N,N-trimethyl chitosan (TMC) fibers were synthesized successfully and the resulting quaternized materials were characterized by FTIR. The designed TMC fibers with different degree of quaternization achieved high water absorption capability. In antibacterial activity study, TMC fibers showed high antibacterial activity than chitosan fibers against the gram-negative bacteria Escherichia coli (>63%) and gram-positive bacteria Staphylococcus aureus (>99%). TMC fibers exhibited no obvious cytotoxicity to mouse embryo fibroblast cells with low extraction concentrations (<0.05g/mL). In animal wound healing test, TMC2 fibers could significantly enhance wound re-epithelialization and contraction compared with the control (chitosan fibers). In conclusion, TMC fibers have a potential to be used as wound dressing materials.

  14. Early changes of dog esophageal mucosa induced by N-ethyl-N'-nitro-N-nitrosoguanidine.

    PubMed

    Takubo, K; Shisa, H; Futatsuki, K; Sasajima, K

    1981-12-01

    Early changes in the esophageal mucosa of dogs induced by N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) were studied. Seven one-year-old beagle dogs were given a solution of 250 micrograms ENNG/ml to drink ad libitum for 4 months. Three different kinds of lesions (10 erosive carcinomas, 4 slightly elevated microcarcinomas and 19 leukoplakias) were recognized. These three kinds of lesions were not located adjacent to one another, and were surrounded by almost normal stratified squamous epithelium. The foci of the carcinomas revealed an abrupt transition to normal epithelium and were considered to have arisen abruptly from normal esophageal epithelium. The histogenesis of squamous cell carcinomas of the esophagus in dogs may differ from that in man.

  15. catena-Poly[[(N,N-di-methyl-cyanamide-κN)lithium]-μ3-bromido].

    PubMed

    Xie, Qianwen; Tong, Hongbo; Zhou, Meisu

    2014-02-01

    The title complex, [LiBr(C3H6N2)] n , is the unexpected product of a reaction beteween (Dipp)N(Li)SiMe3 (Dipp = 2,6-diiso-propyl-phen-yl), Me2NCN and CuBr. The compound is a one-dimensional polymer with a step structure derived from the association of inversion dimers, formed by bromido ligands bridging two Li(+) cations, each of which carries a di-methyl-cyanamide ligand. The planar (LiBr)2 unit of the polymer core has a regular rhombic shape [Li-Br-Li 77.55 (16)° and Br-Li-Br 102.45 (16)°]. These (LiBr·NCNMe2)2 dimers represent the repeat unit of a polymer system propagated by additional Br-Li and Li-Br bonds generating an infinite step structure along the a-axis direction.

  16. Crystal structure of 2-carboxy- N,N,N- trimethylethanaminium bromide monohydrate

    NASA Astrophysics Data System (ADS)

    Chen, Xiao-Ming; Mak, Thomas C. W.

    1991-05-01

    A new betaine derivative, 2-carboxy- N,N,N-trimethylethanaminium bromide monohydrate, (Me 3NCH 2CH 2COOH)Br·H 2O, I, has been synthesized and characterized by X-ray crystallography. Compound I crystallizes in space group Pnma (no. 62), with a=10.452(2), b=6.855(2), c=13.737(2)Å, and Z=4. The structure ( RF=0.047 for 881 observed (⋎ FO⋎&>;6⋎ FO⋎) Mo Kα data) features a hydrogen-bonded (BR -·H 2O) ∞zigzag chain running parallel to the a axis. The quaternary ammonium ions, each attaining Cs molecular symmetry, are laterally attached by donor hydrogen bonds to the exposed water molecules of the zigzag chain. The crystal structure consists of layers each having a zipper-like arrangement of the quaternary ammonium "side-chains".

  17. Study of N-n-butyl-N-(2-nitroxyethyl)nitramine in RDX based gun propellant.

    PubMed

    Damse, R S; Omprakash, B; Tope, B G; Chakraborthy, T K; Singh, Amarjit

    2009-08-15

    The current trend in the development of gun propellant is to replace the non-energetic plasticizers with the energetic plasticizer. This leads to better energetic performance of gun propellant. The purpose of the present paper is to explore the possibility of enhancing the ballistic performance of RDX based gun propellant by incorporating an energetic plasticizer into the propellant composition. Compositions containing N-n-butyl-N-(2-nitroxyethyl)nitramine (Bu-NENA) as an energetic plasticizer with varying percentage of RDX have been studied theoretically and experimentally. Performance in terms of ballistic parameters, sensitivity, thermal characteristics, stability and mechanical properties was evaluated and compared with the vis-à-vis compositions containing dioctylphthalate as a non-energetic plasticizer. Experimental data on comparative study indicates that Bu-NENA based propellants are superior to DOP based propellants in respect of ballistic performance.

  18. N2O FIELD STUDY

    EPA Science Inventory

    The report gives results of measurements of nitrous oxide (N2O) emissions from coal-fired utility boilers at three electric power generating stations. Six units were tested, two at each site, including sizes ranging from 165 to 700 MW. Several manufacturers and boiler firing type...

  19. N2O FIELD STUDY

    EPA Science Inventory

    The report gives results of measurements of nitrous oxide (N2O) emissions from coal-fired utility boilers at three electric power generating stations. Six units were tested, two at each site, including sizes ranging from 165 to 700 MW. Several manufacturers and boiler firing type...

  20. N2O and NOy

    NASA Technical Reports Server (NTRS)

    Kawa, S. R.; Jackman, C. H.; Douglass, A. R.; Strahan, S. E.

    2003-01-01

    The principal loss processes for ozone in the stratosphere are either directly or indirectly closely coupled to the abundance and distribution of reactive oxides of nitrogen (NOy). The main source of NOy in the stratosphere is N2O, a trace gas that is changing significantly as a result of anthropogenic forcing. Thus diagnosis of the distributions of N2O, NOy, and their coupling is required to evaluate any chemistry-climate model aspiring to accurately simulate ozone change. In the NASA Assessment of the Effects of High-speed Aircraft in the Stratosphere: 1998 we found that the sensitivity of various models ozone to perturbation did correspond consistently with their background NOy distribution. Coordinated NOy and N2O mixing ratio distributions are available from observations: ER-2 aircraft in the lower stratosphere and ATMOS and balloon profiles to higher altitudes at a subset of latitudes and seasons. Although close comparison to these diagnostics is crucial, unfortunately the distributions are due to a combination of transport and chemical processes, and isolating the source of differences is not always simple. However, in combination with other transport and photochemical diagnostics, comparison with N2O and NOy can be very instructive in evaluation of model processes and performance.

  1. Modeling of the N Cycle

    USDA-ARS?s Scientific Manuscript database

    Simulation models provide a summary of the quantitative understanding of the system being modeled. The objective of this book chapter is to review the wealth of literature and the documented simulation models currently available that deal with the nitrogen (N) cycle. The fast increase in computer p...

  2. Bis(μ-N,N-di-allyl-dithio-carbamato)bis[(N,N-di-allyl-dithio-carbamato)cadmium].

    PubMed

    Onwudiwe, Damian C; Hrubaru, Madalina; Hosten, Eric C; Arderne, Charmaine

    2017-09-01

    The title compound, [Cd2(C7H10NS2)4], is a neutral dinuclear cadmium(II) complex bearing four bis N,N-di-allyl-di-thio-carbamate ligands coordinating to two Cd(II) cations. In each of the monomeric subunits, there are four S atoms of two di-thio-carbamate ligands [Cd-S = 2.5558 (3), 2.8016 (3), 2.6050 (3) and 2.5709 (3) Å] that coordinate to one Cd(II) atom in a bidentate mode. The dimers are located over an inversion centre bridged by two additional bridging Cd-S bonds [2.6021 (3) Å], leading to a substantial distortion of the geometry of the monomeric subunit from the expected square-planar geometry. The five-coordinate environment around each of the Cd(II) ions in the dimer is best described as substanti-ally tetra-gonally distorted square pyramidal. The di-thio-carbamate groups are themselves planar and are also coplanar with the Cd(II) ions. The negative charge on these groups is delocalized by resonance across the S atoms bound to the Cd(II) cation. This delocalization of the π electrons in the di-thio-carbamate groups also extends to the C-N bonds as they reveal significant double bond character [C-N = 1.3213 (16) and 1.3333 (15) Å].

  3. Polarographic investigation of Cu(II) complexes with N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine.

    PubMed

    Norkus, E; Vaskelis, A; Zakaité, I; Reklaitis, J

    1995-11-01

    During investigation of the formation of Cu(2+) ion complexes with N,N,N',N'-tetrakis-(2-hydroxypropyl)-ethylenediamine (Quadrol-Q) by means of constant current polarography (20 degrees C, ionic strength J = 3 mol l(-1)), the possibility of the formation of two complex compounds; CuQ(2+) and CuQ(2+)(2), was shown within the pH range from 6 to 8. The logarithms of the stability constants for these compounds are 10.6 +/- 0.5 and 14.6 +/- 0.4 respectively. Cu(II) complexation increases sharply when the pH increases from 8 to 10. It was shown that the data at a pH of greater than 10 are in accordance with the existence of the hydroxy complexes CuQ(OH)(2) and CuQ(2)(OH)(2), the logarithms of the stability constants being 26.9 +/- 0.5 and 29.1 +/- 0.3.

  4. Cover crops and N credits

    USDA-ARS?s Scientific Manuscript database

    Cover crops often provide many short- and long-term benefits to cropping systems. Legume cover crops can significantly reduce the N fertilizer requirement of non-legume cash crops that follow. The objectives of this presentation were to: I) educate stakeholders about the potential benefits of cover ...

  5. Evaluation of N,N-dialkylamides as promising process extractants

    NASA Astrophysics Data System (ADS)

    Pathak, P. N.; Prabhu, D. R.; Kanekar, A. S.; Manchanda, V. K.

    2010-03-01

    Studies carried out at BARC, India on the development of new extractants for reprocessing of spent fuel suggested that while straight chain N,N-dihexyloctanamide (DHOA) is promising alternative to TBP for the reprocessing of irradiated uranium based fuels, branched chain N,N-di(2-ethylhexyl)isobutyramide (D2EHIBA) is suitable for the selective recovery of 233U from irradiated Th. In advanced fuel cycle scenarios, the coprocessing of U/Pu stream appears attractive particularly with respect to development of proliferation resistant technologies. DHOA extracted Pu(IV) more efficiently than TBP, both at trace-level concentration as well as under uranium/plutonium loading conditions. Uranium extraction behavior of DHOA was however, similar to that of TBP during the extraction cycle. Stripping behavior of U and Pu (without any reductant) was better for DHOA than that of TBP. It was observed during batch studies that whereas 99% Pu is stripped in four stages in case of DHOA, only 89% Pu is stripped in case of TBP under identical experimental conditions. DHOA offered better fission product decontamination than that of TBP. GANEX (Group ActiNide EXtraction) and ARTIST (Amide-based Radio-resources Treatment with Interim Storage of Transuranics) processes proposed for actinide partitioning use branched chain amides for the selective extraction of uranium from spent fuel feed solutions. The branched-alkyl monoamide (BAMA) proposed to be used in ARTIST process is N,N-di-(2-ethylhexyl)butyramide (D2EHBA). In this context, the extraction behavior of U(VI) and Pu(IV) were compared using D2EHIBA, TBP, and D2EHBA under similar concentration of nitric acid (0.5 — 6M) and of uranium (0-50g/L). These studies suggested that D2EHIBA is a promising extractant for selective extraction of uranium over plutonium in process streams. Similarly, D2EHIBA offered distinctly better decontamination of 233U over Th and fission products under THOREX feed conditions. The possibility of simultaneous

  6. Cosmological N-body Simulation

    NASA Astrophysics Data System (ADS)

    Lake, George

    1994-05-01

    .90ex> }}} The ``N'' in N-body calculations has doubled every year for the last two decades. To continue this trend, the UW N-body group is working on algorithms for the fast evaluation of gravitational forces on parallel computers and establishing rigorous standards for the computations. In these algorithms, the computational cost per time step is ~ 10(3) pairwise forces per particle. A new adaptive time integrator enables us to perform high quality integrations that are fully temporally and spatially adaptive. SPH--smoothed particle hydrodynamics will be added to simulate the effects of dissipating gas and magnetic fields. The importance of these calculations is two-fold. First, they determine the nonlinear consequences of theories for the structure of the Universe. Second, they are essential for the interpretation of observations. Every galaxy has six coordinates of velocity and position. Observations determine two sky coordinates and a line of sight velocity that bundles universal expansion (distance) together with a random velocity created by the mass distribution. Simulations are needed to determine the underlying structure and masses. The importance of simulations has moved from ex post facto explanation to an integral part of planning large observational programs. I will show why high quality simulations with ``large N'' are essential to accomplish our scientific goals. This year, our simulations have N >~ 10(7) . This is sufficient to tackle some niche problems, but well short of our 5 year goal--simulating The Sloan Digital Sky Survey using a few Billion particles (a Teraflop-year simulation). Extrapolating past trends, we would have to ``wait'' 7 years for this hundred-fold improvement. Like past gains, significant changes in the computational methods are required for these advances. I will describe new algorithms, algorithmic hacks and a dedicated computer to perform Billion particle simulations. Finally, I will describe research that can be enabled by

  7. Antigenotoxicity of galangin against N-methyl-N-nitrosourea.

    PubMed

    Sohn, S J; Huh, I H; Au, W W; Heo, M Y

    1998-06-18

    Using the Ames bacterial mutagenicity test and an in vivo micronucleus test, we investigated the antigenotoxic effect of galangin against the genotoxicity of N-methyl-N-nitrosourea (MNU). In the Ames assay, galangin showed an antimutagenic effect towards MNU-induced mutagenicity of Salmonella typhimurium TA 100. In mice, galangin showed an anticlastogenic effect against MNU-induced micronuclei in polychromatic erythrocytes in the MNPCE in mouse bone marrow cells. On the other hand, galangin is neither mutagenic nor clastogenic in both assays. Results from our in vitro and in vivo studies indicate that galangin is capable of suppressing the mutagenicity and clastogenicity of MNU. Therefore, galangin may be a useful chemopreventive agent against potential long-term health effects from genotoxic environmental agents.

  8. Equilibrium among potassium polytellurides in N,N-dimethylformamide solution

    NASA Astrophysics Data System (ADS)

    McAfee, Jason L.; Andreatta, Jeremy R.; Sevcik, Richard S.; Schultz, Linda D.

    2012-08-01

    Reactions between elemental potassium and tellurium in N,N-dimethylformamide (DMF) are monitored using UV-visible spectroscopy and compared with those in liquid ammonia solution. In liquid ammonia, the elements react together, via a step-wise sequence, to form polytellurides, each of which is characterized by a distinctive color, the highest being potassium tritelluride. However, when the elements are combined in DMF, these distinctive color changes are not observed - the solution develops an initial plum color, which gradually darkens to purple as the reaction progresses. UV-visible and Raman spectroscopic studies indicate that equilibrium exists among the mono-, di-, and tritelluride in DMF. This equilibrium is not seen in liquid ammonia solution due to the insolubility of potassium monotelluride in that solvent. Spectral data also indicate that potassium tetratelluride is formed in DMF solution.

  9. N-chlorinated poly(N-isopropylacrylamide) microgels.

    PubMed

    Wang, Zuohe; Lam, Wing Yan; Pelton, Robert

    2013-10-22

    The treatment of poly(N-isopropylacrylamide) (PNIPAM) microgels with aqueous bleach (NaClO) at pH 10.5 resulted in the partial conversion of the amide hydrogen to the corresponding chloramide. N-Chlorinated microgels poly(NIPAM-co-NIPAMCl) are more hydrophobic than the parent PNIPAM microgels. Thus, the volume phase transition temperature decreases with increasing chlorination. During chlorination, the microgels coagulate once they undergo a volume phase transition. The chlorination reaction stops once the microgels dehydrate and coagulate, presumably as a result of the decreased diffusion rate of the ClO(-) anion into the microgels. The microgels are reversibly dechlorinated by glutathione (GSH), first giving PNIPAM shell + poly(NIPAM-co-NIPAMCl) core microgels. Because GSH is an important redox actor in biological cells, this work suggests that chlorinated microgels may be employed to deliver active chlorine to targeted cells.

  10. Mouse Mutagenesis Using N-Ethyl-N-Nitrosourea (ENU).

    PubMed

    Salinger, Andrew P; Justice, Monica J

    2008-04-01

    INTRODUCTIONThis protocol describes chemical mutagenesis of male mice using N-ethyl-N-nitrosourea (ENU), which is the most efficient method for obtaining mouse mutations in phenotype-driven screens. A fractionated dose of ENU, an alkylating agent, can produce a mutation rate as high as 1.5 × 10(-3) in male mouse spermatogonial stem cells. Treatment with ENU produces point mutations that provide a unique mutant resource: They reflect the consequences of single gene changes independent of position effects, provide a fine structure dissection of protein function, display a range of mutant effects from complete or partial loss of function to exaggerated function, and discover gene functions in an unbiased manner. After treatment with ENU, mice are mated in genetic screens designed to uncover mutations of interest. Screens for dominant, recessive, and modifying mutations can be performed.

  11. [Elimination of N,N-dimethyltryptamine by urine].

    PubMed

    Spatz, N; Spatz, H; Mesones Arroyo, H L; Rosan, T; Brengio, F

    1993-09-01

    N,N-dimethiltryptamine (DMT) in urine has been quantified on an 83-psychiatric patient sample. Sample covered patients who had sometimes been administered neuroleptic drugs as well as patients with some particular symptomatology associated to psychotic disorders such as hallucinations, delusions, perception disorders, etc. 43.3% (36 cases) evidenced an abnormally high DMT in urine (0.9-13.5 mcg/24 h). Higher values were more frequently found in both schizophrenic patients, and non-schizophrenic patients with either hallucinations, delusions, anorexia or bulimia. Most patients with DMT normal values (< 0.5 mcg/24 h) presented either mental retardation, cerebral atrophy or dysrhythmias. A very good correlation was found between urinary DMT abnormally high values, and patients' improvement after such patients had been treated with neuroleptic drugs.

  12. Comprehensive extraction study using N,N-dioctyldiglycolamic acid.

    PubMed

    Shimojo, Kojiro; Nakai, Ayaka; Okamura, Hiroyuki; Saito, Takumi; Ohashi, Akira; Naganawa, Hirochika

    2014-01-01

    We report on the acid dissociation constants (Ka) of diglycolamic acid-type ligands together with comprehensive data on the extraction performance of N,N-dioctyldiglycolamic acid (DODGAA) for 54 metal ions. The pKa of the diglycolamic acid framework was determined to be 3.54 ± 0.03 in water (0.1 M LiCl, 25°C) by potentiometric titration, indicating that DODGAA is strongly acidic compared with acetic acid. DODGAA can quantitatively transfer various metal ions among the 54 metal ions through a proton-exchange reaction, and provides excellent extraction performance and separation ability for rare-earth metal ions, In(III), Fe(III), Hg(II), and Pb(II) among the 54 metal ions.

  13. [Effect of reduced N application on soil N residue and N loss in maize-soybean relay strip intercropping system].

    PubMed

    Liu, Xiao-Ming; Yong, Tai-Wen; Liu, Wen-Yu; Su, Ben-Ying; Song, Chun; Yang, Feng; Wang, Xiao-Chun; Yang, Wen-Yu

    2014-08-01

    A field experiment was conducted in 2012, including three planting pattern (maize-soybean relay strip intercropping, mono-cultured maize and soybean) and three nitrogen application level [0 kg N x hm(-2), 180 kg N x hm(-2) (reduced N) and 240 kg N x hm(-2) (normal N)]. Fields were assigned to different treatments in a randomized block design with three replicates. The objective of this work was to analyze the effects of planting patterns and nitrogen application rates on plant N uptake, soil N residue and N loss. After fertilization applications, NH4(+)-N and NO3(-)-N levels increased in the soil of intercropped maize but decreased in the soil of intercropped soybean. Compared with mono-crops, the soil N residue and loss of intercropped soybean were reduced, while those of intercropped maize were increased and decreased, respectively. With the reduced rate of N application, N residue rate, N loss rate and ammonia volatilization loss rate of the maize-soybean intercropping relay strip system were decreased by 17.7%, 21.5% and 0.4% compared to mono-cultured maize, but increased by 2.0%, 19.8% and 0.1% compared to mono-cultured soybean, respectively. Likewise, the reduced N application resulted in reductions in N residue, N loss, and the N loss via ammonia volatilization in the maize-soybean relay strip intercropping system compared with the conventional rate of N application adopted by local farmers, and the N residue rate, N loss rate and ammonia volatilization loss rate reduced by 12.0%, 15.4% and 1.2%, respectively.

  14. Finite SU(N)k Unification

    NASA Astrophysics Data System (ADS)

    Ma, Ernest; Mondragon, Myriam; Zoupanos, G.

    2004-12-01

    We consider N = 1 supersymmetric gauge theories based on the group SU(N)1 × SU(N)2 × ... × SU(N)k with matter content (N,N*,1,...,1)+(1,N,N*,...,1)+...+(N*,1,1,...,N) as candidates for the unification symmetry of all particles. In particular we examine to which extent such theories can become finite and we find that a necessary condition is that there should be exactly three families. We discuss further some phenomenological issues related to the cases (N,k) = (3, 3), (3, 4) and (4,3), in an attempt to choose those theories that can become also realistic. Thus we are naturally led to consider the SU(3)3 model which we first promote to an all-loop finite theory and then we study its additional predictions concerning the top quark mass, Higgs mass and supersymmetric spectrum.

  15. Concise synthesis of N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine starting with bufotenine from Brazilian Anadenanthera ssp..

    PubMed

    Moreira, Leandro A; Murta, Maria M; Gatto, Claudia C; Fagg, Christopher W; dos Santos, Maria L

    2015-04-01

    Bufotenine (1, 5-hydroxy-N,N-dimethyltryptamine) was isolated from seeds of Anadenanthera spp., a tree widespread in the Brazilian cerrado, using an efficient acid-base shakeout protocol. The conversion of bufotenine into N,N-dimethyltryptamine (4) and 5-methoxy-N,N-dimethyltryptamine (5) was accomplished through an innovative and short approach featuring the use of novel bufotenine-aminoborane complex (7). Furthermore, an easy methodology for conversion of bufotenine into 5-hydroxy-N,N,N-trimethyltryptamine (6) was well-established. This is the first study that highlights bufotenine as a resource for the production of N,N-dimethyltryptamines for either pharmacological and toxicological investigations or for synthetic purposes.

  16. A comparative study on the neurotoxicity of n-pentane, n-hexane, and n-heptane in the rat.

    PubMed Central

    Takeuchi, Y; Ono, Y; Hisanaga, N; Kitoh, J; Sugiura, Y

    1980-01-01

    The neurotoxicity of n-pentane, n-hexane, and n-heptane have been studied in Wistar strain male rats after exposure to 3000 ppm of n-pentane, n-hexane, or n-heptane for 12 hours a day for 16 weeks. The nerve conduction velocity and the distal latency were measured before the beginning of the exposure and after exposure for four, eight, 12, and 16 weeks. The experiment showed that n-hexane disturbed the conduction velocity of the motor nerve and the mixed nerve and prolonged the distal latency in the rat's tail, but that n-pentane and n-heptane did not. The light and electron microscopic examination showed that the peripheral nerve, the neuromuscular junction, and the muscle fibre of the rats exposed to n-hexane were severely impaired, but those of the rats exposed to n-pentane or n-heptane showed no particular changes even after 16 weeks of exposure. These results show that n-hexane is far more toxic to the peripheral nerve of the rat than n-pentane or n-heptane. It is necessary to study the neurotoxicity of other petroleum hydrocarbons, since some reports suggest that petroleum solvents might possibly contain neurotoxic hydrocarbons other than n-hexane. Images PMID:7426474

  17. Descriptions of Kashmira dimorphicauda gen. n., sp. n. and Aphelenchoides hypotris sp. n. from Kashmir Valley, India

    USDA-ARS?s Scientific Manuscript database

    Kashmira dimorphicauda gen. n., sp. n. and Aphelenchoides hypotris sp. n. are described and illustrated from freshwater stream soil in Kashmir Valley, India. Kashmira gen. n. is characterized by having dimorphic tails: coinoid-spicate tail in female and subcylindroid with rounded, non-spicate tip wi...

  18. 40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

  19. 40 CFR 721.10576 - Polyalkenyl, N,N'-bistriazole (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polyalkenyl, N,N'-bistriazole (generic... Specific Chemical Substances § 721.10576 Polyalkenyl, N,N'-bistriazole (generic). (a) Chemical substance... polyalkenyl, N,N'-bistriazole (PMN P-09-486) is subject to reporting under this section for the significant...

  20. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN P...

  1. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN P...

  2. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  3. 40 CFR 721.10576 - Polyalkenyl, N,N'-bistriazole (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polyalkenyl, N,N'-bistriazole (generic... Specific Chemical Substances § 721.10576 Polyalkenyl, N,N'-bistriazole (generic). (a) Chemical substance... polyalkenyl, N,N'-bistriazole (PMN P-09-486) is subject to reporting under this section for the significant...

  4. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  5. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  6. 40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

  7. 40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

  8. 40 CFR 721.10159 - 1-Docosanamine, N,N-dimethyl-.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 1-Docosanamine, N,N-dimethyl-. 721... Substances § 721.10159 1-Docosanamine, N,N-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-docosanamine, N,N-dimethyl- (PMN P-07-587...

  9. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN P...

  10. 40 CFR 721.10159 - 1-Docosanamine, N,N-dimethyl-.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 1-Docosanamine, N,N-dimethyl-. 721... Substances § 721.10159 1-Docosanamine, N,N-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-docosanamine, N,N-dimethyl- (PMN P-07-587...

  11. 40 CFR 721.10159 - 1-Docosanamine, N,N-dimethyl-.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 1-Docosanamine, N,N-dimethyl-. 721... Substances § 721.10159 1-Docosanamine, N,N-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-docosanamine, N,N-dimethyl- (PMN P-07-587...

  12. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN...

  13. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is...

  14. 40 CFR 721.10159 - 1-Docosanamine, N,N-dimethyl-.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 1-Docosanamine, N,N-dimethyl-. 721... Substances § 721.10159 1-Docosanamine, N,N-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-docosanamine, N,N-dimethyl- (PMN...

  15. 40 CFR 180.384 - Mepiquat (N,N-dimethylpip-eridinium); tolerances for residues.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Mepiquat (N,N-dimethylpip-eridinium... Tolerances § 180.384 Mepiquat (N,N-dimethylpip-eridinium); tolerances for residues. (a) General. (1) Tolerances are established for residues of the plant growth regulator mepiquat (N,N-dimethylpiperidinium) in...

  16. 40 CFR 721.10159 - 1-Docosanamine, N,N-dimethyl-.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 1-Docosanamine, N,N-dimethyl-. 721... Substances § 721.10159 1-Docosanamine, N,N-dimethyl-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as 1-docosanamine, N,N-dimethyl- (PMN P-07-587...

  17. 40 CFR 721.4080 - MNNG (N-methyl-N′-nitro-N-nitrosoguanidine).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false MNNG (N-methyl-Nâ²-nitro-N... Specific Chemical Substances § 721.4080 MNNG (N-methyl-N′-nitro-N-nitrosoguanidine). (a) Chemical substance and significant new use subject to reporting. (1) The chemical substance MNNG (N-methyl-N′-nitro-N...

  18. 40 CFR 721.520 - Alanine, N-(2-carboxyethyl)-N-alkyl-, salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alanine, N-(2-carboxyethyl)-N-alkyl... Specific Chemical Substances § 721.520 Alanine, N-(2-carboxyethyl)-N-alkyl-, salt. (a) Chemical substance... alanine, N-(2-carboxyethyl)-N- alkyl-, salt (P-89-336) is subject to reporting under this section for the...

  19. 40 CFR 721.275 - Halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Halogenated-N-(2-propenyl)-N... New Uses for Specific Chemical Substances § 721.275 Halogenated-N-(2-propenyl)-N-(substituted phenyl... identified generically as halogenated-N-(2-propenyl)-N-(substituted phenyl) acetamide (P-83-1085) is subject...

  20. 40 CFR 721.4090 - Ethanaminium, N-[bis(diethylamino)-methylene]-N-ethyl-, bromide.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Ethanaminium, N- -N-ethyl-, bromide... Substances § 721.4090 Ethanaminium, N- -N-ethyl-, bromide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as ethanaminium, N- -N-ethyl-, bromide (PMN P...

  1. 40 CFR 721.3848 - Glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Glycine, N-(carboxymethyl)-N-dodecyl... Specific Chemical Substances § 721.3848 Glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt. (a... glycine, N-(carboxymethyl)-N-dodecyl-, monosodium salt (PMN P-00-469; CAS No. 141321-68-8) is subject to...

  2. Influence of internal electric fields on band gaps in short period GaN/GaAlN and InGaN/GaN polar superlattices

    SciTech Connect

    Gorczyca, I. Skrobas, K.; Suski, T.; Christensen, N. E.; Svane, A.

    2015-08-21

    The electronic structures of short period mGaN/nGa{sub y}Al{sub 1−y}N and mIn{sub y}Ga{sub 1-y}N/nGaN superlattices grown along the wurtzite c axis have been calculated for different alloy compositions y and various small numbers m of well- and n of barrier-monolayers. The general trends in gap behavior can, to a large extent, be related to the strength of the internal electric field, E, in the GaN and InGaN quantum wells. In the GaN/GaAlN superlattices, E reaches 4 MV/cm, while in the InGaN/GaN superlattices, values as high as E ≈ 6.5 MV/cm are found. The strong electric fields are caused by spontaneous and piezoelectric polarizations, the latter contribution dominating in InGaN/GaN superlattices. The influence of different arrangements of In atoms (indium clustering) on the band gap values in InGaN/GaN superlattices is examined.

  3. Performance improvement of GaN-based LEDs with step stage InGaN/GaN strain relief layers in GaN-based blue LEDs.

    PubMed

    Jia, Chuanyu; Yu, Tongjun; Lu, Huimin; Zhong, Cantao; Sun, Yongjian; Tong, Yuzhen; Zhang, Guoyi

    2013-04-08

    The performance of nitride-based LEDs was improved by inserting dual stage and step stage InGaN/GaN strain relief layer (SRL) between the active layer and n-GaN template. The influences of step stage InGaN/GaN SRL on the structure, electrical and optical characteristics of GaN-based LEDs were investigated. The analysis of strain effect on recombination rate based k·p method indicated 12.5% reduction of strain in InGaN/GaN MQWs by inserting SRL with step stage InGaN/GaN structures. The surface morphology was improved and a smaller blue shift in the electroluminescence (EL) spectral with increasing injection current was observed for LEDs with step stage SRL compared with conventional LEDs. The output power of LEDs operating at 20 mA was about 15.3 mW, increased by more than 108% by using step stage InGaN/GaN SRL, which shows great potential of such InGaN/GaN SRL in modulating InGaN/GaN MQWs optical properties based on its strain relief function.

  4. Neutron capture and (n,2n) measurements on 241Am

    SciTech Connect

    Vieira, D; Jandel, M; Bredeweg, T; Bond, E; Clement, R; Couture, A; Haight, R; O'Donnell, J; Reifarth, R; Ullmann, J; Wilhelmy, J; Wouters, J; Tonchev, A; Hutcheson, A; Angell, C; Crowell, A; Fallin, B; Hammond, S; Howell, C; Karowowski, H; Kelley, J; Pedroni, R; Tornow, W; Macri, R; Agvaanluvsan, U; Becker, J; Dashdorj, D; Stoyer, M; Wu, C

    2007-07-18

    We report on a set of neutron-induced reaction measurements on {sup 241}Am which are important for nuclear forensics and advanced nuclear reactor design. Neutron capture measurements have been performed on the DANCE detector array at the Los Alamos Neutron Scattering CEnter (LANSCE). In general, good agreement is found with the most recent data evaluations up to an incident neutron energy of {approx} 300 keV where background limits the measurement. Using mono-energetic neutrons produced in the {sup 2}H(d,n){sup 3}He reaction at Triangle University Nuclear Laboratory (TUNL), we have measured the {sup 241}Am(n,2n) excitation function from threshold (6.7 MeV) to 14.5 MeV using the activation method. Good agreement is found with previous measurements, with the exception of the three data points reported by Perdikakis et al. around 11 MeV, where we obtain a much lower cross section that is more consistent with theoretical estimates.

  5. N,N-diethyl-m-toluamide transformation in river water.

    PubMed

    Calza, P; Medana, C; Raso, E; Giancotti, V; Minero, C

    2011-09-01

    The paper deals with the aqueous environmental fate of N,N-diethyl-m-toluamide (DEET), one of the most widespread and efficient mosquito repellents. The investigation involved monitoring of the DEET decomposition and the identification of intermediate compounds. Initially, control experiments in the dark and under illumination were performed on sterilized and river water spiked with DEET, with the aim to simulate all possible transformation processes occurring in aquatic system. Under illumination, DEET was degraded and transformed into numerous organic intermediate compounds, 37 of which could be identified. Several isomeric species were formed and characterized by analysing MS and MS(n) spectra, and by comparison with parent molecule fragmentation pathways. These laboratory simulation experiments were verified in the field to check the mechanism previously supposed. River water was sampled and analysed at eight sampling points. Among the transformation products (TPs) identified in river water spiked with DEET, twelve of them were also found in natural river water. The transformation occurring in aquatic systems involved dealkylation, mono- and poly-hydroxylation followed by oxidation of the hydroxyl groups and cleavage of the alkyl chains. Two TPs were principally formed in dark condition, while the others are mainly produced through indirect photolysis processes mediated by natural photosensitizers. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. PARTITIONING THE RELATIVE INFLUENCE OF SOIL N, MYCORRHIZAE, AND FOLIAR N UPTAKE ON FOLIAR δ15N PATTERNS: CAN WE DETECT FOLIAR UPTAKE OF REACTIVE N?

    NASA Astrophysics Data System (ADS)

    Vallano, D.; Sparks, J. P.

    2009-12-01

    Vegetation is an important sink for atmospheric reactive N in N-limited systems and may be capable of incorporating reactive N compounds directly into leaves through the foliar uptake pathway. A proxy for atmospheric reactive N entering vegetation would be useful to estimate the impact of direct foliar N uptake on plant metabolism. Natural abundance foliar N isotopic composition (δ15N) is a practical tool for this purpose because plant-available N sources often have different isotopic compositions. Current understanding of foliar δ15N suggests these values primarily represent the integration of soil δ15N, direct foliar N uptake, mycorrhizal fractionation, and within-plant fractionations. Using a potted plant mesocosm system, we estimated the influence of mycorrhizae on foliar δ15N patterns in red maple (Acer rubrum) seedlings along an N deposition gradient in New York State. We found that mycorrhizal associations altered foliar δ15N in red maple seedlings from 0.03 - 1.01‰ across sites. Along the same temporal and spatial scales, we examined the influence of soil δ15N, foliar N uptake, and mycorrhizae on foliar δ15N in adult stands of American beech (Fagus grandifolia), black birch (Betula lenta), red maple (A. rubrum), and red oak (Quercus rubra). Using multiple regression models, atmospheric NO2 concentration explained 0%, 69%, 23%, and 45% of the residual variation in foliar δ15N remaining in American beech, red maple, red oak, and black birch, respectively, after accounting for soil δ15N. Our results suggest that foliar δ15N may be used to estimate pollution-derived atmospheric reactive N entering vegetation via the foliar N uptake pathway.

  7. "N"-2 Repetition Costs Depend on Preparation in Trials "n"-1 and "n"-2

    ERIC Educational Resources Information Center

    Scheil, Juliane; Kleinsorge, Thomas

    2014-01-01

    In task switching, a common result supporting the notion of inhibitory processes as a determinant of switch costs is the occurrence of "n"-2 repetition costs. Evidence suggests that this effect is not affected by preparation. However, the role of preparation on preceding trials has been neglected so far. In this study, evidence for an…

  8. "N"-2 Repetition Costs Depend on Preparation in Trials "n"-1 and "n"-2

    ERIC Educational Resources Information Center

    Scheil, Juliane; Kleinsorge, Thomas

    2014-01-01

    In task switching, a common result supporting the notion of inhibitory processes as a determinant of switch costs is the occurrence of "n"-2 repetition costs. Evidence suggests that this effect is not affected by preparation. However, the role of preparation on preceding trials has been neglected so far. In this study, evidence for an…

  9. Preparation of N, N, N-trimethyl chitosan via a novel approach using dimethyl carbonate.

    PubMed

    Wu, Meiyan; Long, Zhu; Xiao, Huining; Dong, Cuihua

    2017-08-01

    N,N,N-trimehtyl chitosan (TMC) is a water-soluble derivate of chitosan, which has been widely used as a biomedical material due to its excellent biocompatibility, biodegradability and bacterial properties. To date, TMC can only be prepared by the quaternization of chitosan using alkyl halide or dimethyl sulfate. However, alkyl halide and dimethyl sulfate are highly toxic, cancerigenic for humans, and harmful to the environment. This paper puts forward a novel approach to preparing TMC using dimethyl carbonate as a methylation reagent in an ionic liquid. The as-synthesized O-methyl-free TMC was characterized using NMR, FTIR, XRD and TG analyses. The results showed that TMC with a degree of quaternization of 9.11% was successfully obtained and the crystallinity of chitosan decreased with the increasing degree of N-methylation, the thermal stability of TMC was lower than that of chitosan. Furthermore, the effects of the dose of ionic liquid and dimethyl carbonate were disscussed. Copyright © 2017. Published by Elsevier Ltd.

  10. Synthesis of symmetrical and unsymmetrical N,N'-diaryl guanidines via copper/N-methylglycine-catalyzed arylation of guanidine nitrate.

    PubMed

    Xing, Hui; Zhang, Ye; Lai, Yisheng; Jiang, Yongwen; Ma, Dawei

    2012-06-15

    CuI/N-methylglycine-catalyzed coupling reaction of guanidine nitrate with both aryl iodides and bromides takes place at 70-100 °C, affording symmetrical N,N'-diaryl guanidines with good to excellent yields. Unsymmetrical N,N'-diaryl guanidines can be assembled via monoarylation of guanidine nitrate with aryl iodides bearing a strong electron-withdrawing group and subsequent coupling with another aryl iodide.

  11. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons From n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Curran, H J; Silke, E J

    2008-02-08

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of nine n-alkanes larger than n-heptane, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on our previous mechanisms for the primary reference fuels n-heptane and iso-octane, using the reaction class mechanism construction first developed for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and these mechanisms will be refined further in the future to incorporate greater levels of accuracy and predictive capability. These mechanisms are validated through extensive comparisons between computed and experimental data from a wide variety of different sources. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare reactivities of different n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available for download from our web page.

  12. Polyamines. III. Spectroscopic properties of N, N-bis-(phthalimidopropyl)- N-octylamine and supramolecular interactions in its crystals

    NASA Astrophysics Data System (ADS)

    Brycki, Bogumił; Werner, Justyna; Kowalczyk, Iwona; Borowiak, Teresa; Wolska, Irena

    2010-04-01

    A new derivative of polyamine, N, N-bis-(phthalimidopropyl)- N-octylamine has been synthesized and its structure studied by X-ray diffraction, FTIR, 1H and 13C NMR spectroscopy. The B3LYP and DFT calculations have been carried out. The molecular conformation of N, N-bis-(phthalimidopropyl)- N-octylamine is folded and stabilized by an intramolecular C sbnd H⋯O hydrogen bond. A close similarity to the conformation of N, N-bis-(phthalimidopropyl)- N-propylamine has been found. The both molecules differ by the length of the saturated chains on the N-amine atom. The long N-octyl chain substituent gives rise to the supramolecular structure which is different to that one formed by the N-propyl derivative. The supramolecular structure is driven by weak C sbnd H⋯O and π⋯ π interactions. The optimized bond lengths as well as bond angles for N, N-bis-(phthalimidopropyl)- N-octylamine calculated by B3LYP/6-31G(d,p) approach are compared with the X-ray data. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants have been obtained.

  13. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND... solvents in cotton defoliant formulations containing thidiazuron and diuron as active ingredients. ...

  14. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PESTICIDE PROGRAMS TOLERANCES AND... solvents in cotton defoliant formulations containing thidiazuron and diuron as active ingredients. ...

  15. 15N Isotopic Crop Exchange Residue Studies Suggest that IPCC N Input Methodologies to Assess N2O-N Emissions Should be Reevaluated

    USDA-ARS?s Scientific Manuscript database

    It is difficult to quantify nitrogen (N) losses from agricultural systems to the environment, however we can use 15N isotopic techniques to conduct site specific studies to increase our knowledge about N management and fate. This manuscript synthesizes the review of two selected 15N isotopic studies...

  16. Reactive N emissions from beef cattle feedlots

    USDA-ARS?s Scientific Manuscript database

    Large amounts of nitrogen (N) are fed to meet the nutritional needs of beef cattle in feedlots. However, only from 10 to 15% of fed N is retained in animals. Most N is excreted. Chemical and biological processes transform manure N into ammonia, nitrous oxide and nitrate. These reactive forms of ...

  17. Photochemical N-demethylation of alkaloids.

    PubMed

    Ripper, J A; Tiekink, E R; Scammells, P J

    2001-02-26

    Certain alkaloids were observed to undergo N-demethylation processes under photochemical conditions. Tropine, acetyltropine, tropinone, and atropine were cleanly N-demethylated upon treatment with tetraphenylporphin, oxygen, and light. Dextromethorphan also underwent a N-demethylation reaction, but reacted further to afford an imine. In contrast, 14-acyloxycodeinones underwent a photochemically induced tandem N-demethylation acyl migration.

  18. 40 CFR 721.10193 - 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false 1-Butanaminium, N-(3-aminopropyl)-N-butyl-N-(2-carboxyethyl)-, N-coco acyl derivs., inner salts. 721.10193 Section 721.10193 Protection of... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10193 1-Butanaminium,...

  19. Registration of N614, A3N615, N616, and N617 Shattercane Genetic Stocks with cytoplasmic or nuclear male-sterility and juicy or dry midribs

    USDA-ARS?s Scientific Manuscript database

    Four shattercane [Sorghum bicolor subsp. drummondii (Nees ex Steud) de Wet & Harlan] genetic stocks, N614, A3N615, N616, N617 (Reg. No. XXX, PI 665683 to 665686), with A3 cytoplasmic male-sterility or nuclear male-sterility gene ms3 containing either juicy (dd) or dry (DD) culms were developed joint...

  20. Understanding the acid-base properties of adenosine: the intrinsic basicities of N1, N3 and N7.

    PubMed

    Kapinos, Larisa E; Operschall, Bert P; Larsen, Erik; Sigel, Helmut

    2011-07-11

    Adenosine (Ado) can accept three protons, at N1, N3, and N7, to give H(3) (Ado)(3+) , and thus has three macro acidity constants. Unfortunately, these constants do not reflect the real basicity of the N sites due to internal repulsions, for example, between (N1)H(+) and (N7)H(+). However, these macroconstants are still needed for the evaluations and the first two are taken from our own earlier work, that is, pK(H)(H(3))((Ado)) = -4.02 and pK(H)(H(2))((Ado)) = -1.53; the third one was re-measured as pK(H)(H)((Ado)) = 3.64 ± 0.02 (25 °C; I=0.5 M, NaNO(3)), because it is the main basis for evaluating the intrinsic basicities of N7 and N3. Previously, contradicting results had been published for the micro acidity constant of the (N7)H(+) site; this constant has now been determined in an unequivocal manner, and that of the (N3)H(+) site was obtained for the first time. The micro acidity constants, which describe the release of a proton from an (N)H(+) site under conditions for which the other nitrogen atoms are free and do not carry a proton, decrease in the order pk(N7-N1)(N7(Ado)N1·H)) = 3.63 ± 0.02 > pk(N7-N1)(H·N7(Ado)N1) = 2.15 ± 0.15 > pk(N3-N1,N7)(H·N3(Ado)N1,N7) =1.5 ± 0.3, reflecting the decreasing basicity of the various nitrogen atoms, that is, N1>N7>N3. Application of the above-mentioned microconstants allows one to calculate the percentages (formation degrees) of the tautomers formed for monoprotonated adenosine, H(Ado)(+) , in aqueous solution; the results are 96.1, 3.2, and 0.7% for N7(Ado)N1·H(+), (+)H·N7(Ado)N1, and (+)H·N3(Ado)N1,N7, respectively. These results are in excellent agreement with theoretical DFT calculations. Evidently, H(Ado)(+) exists to the largest part as N7(Ado)N1·H(+) having the proton located at N1; the two other tautomers are minority species, but they still form. These results are not only meaningful for adenosine itself, but are also of relevance for nucleic acids and adenine nucleotides, as they help to understand

  1. Materials considerations for molten salt accelerator-based plutonium conversion systems

    SciTech Connect

    DeVan, J.H.; DiStefano, J.R.; Eatherly, W.P.; Keiser, J.R.; Klueh, R.L.

    1994-12-31

    A Molten-Salt Reactor Program for power applications was initiated at the Oak Ridge National Laboratory in 1956. In 1965 the Molten Salt Reactor Experiment (MSRE) went critical and was successfully operated for several years. Operation of the MSRE revealed two deficiencies in the Hastelloy N alloy that had been developed specifically for molten-salt systems. The alloy embrittled at elevated temperatures as a result of exposure to thermal neutrons (radiation damage) and grain boundary embrittlement occurred in materials to fuel salt. Intergranular cracking was found to be associated with fission products, viz. tellurium. An improved Hastelloy N composition was subsequently developed that had better resistance to both of these problems. However, the discovery that fission product cracking could be significantly decreased by making the salt sufficiently reducing offers the prospect of improved compatibility with molten salts containing fission products and resistance to radiation damage in ABC applications. Recommendations are made regarding the types of corrosion tests and mechanistic studies needed to qualify materials for operation with PuF{sub 3}-containing molten salts.

  2. Materials corrosion in molten LiF-NaF-KF eutectic salt under different reduction-oxidation conditions

    SciTech Connect

    Sellers, R. S.; Cheng, W. J.; Anderson, M. H.; Sridharan, K.; Wang, C. J.; Allen, T. R.

    2012-07-01

    Molten fluoride salts such as FLiNaK (LiF-NaF-KF: 46.5-11.5-42 mol %) have been proposed for use as secondary reactor coolants, media for transfer of high temperature process heat from nuclear reactors to chemical plants, and for concentrated solar power thermal energy storage. In molten fluoride salts, passive oxide films are chemically unstable, and corrosion is driven largely by the thermodynamically driven dissolution of alloying elements into the molten salt environment. Two alloys, Hastelloy{sup R} N and 316L stainless steel were exposed to molten FLiNaK salt in a 316L stainless steel crucible under argon cover gas for 1000 hours at 850 deg. C. Graphite was present in some of the crucibles with the goal of studying corrosion behavior of relevant reactor material combinations. In addition, a technique to reduce alloy corrosion through modification of the reduction-oxidation state was tested by the inclusion of zirconium to the system. Corrosion of 316L stainless steel was noted to occur primarily through surface depletion of chromium, an effect that was enhanced by the presence of graphite. Hastelloy{sup R} N experienced weight gain through electrochemical plating of corrosion products derived from the 316L stainless steel crucible. In the presence of zirconium, both alloys gained weight through plating of zirconium and as a result formed intermetallic layers. (authors)

  3. N2, equivocator to climate.

    NASA Astrophysics Data System (ADS)

    Dewey, M. C.; Goldblatt, C.

    2016-12-01

    As alcohol is the equivocator to lechery (Act 3, Scene 2 of Macbeth), so the atmospheric inventory of di-nitrogen is an equivocator to surface temperature. Too little, and the surface will be cold, for there will be little pressure broadening of the greenhouse gasses. Too much, and Rayleigh scattering will dominate, increasing planetary albedo. We will present 1-D cloudy models, where we explore N2-CO2 parameter space.

  4. 100-N Area underground storage tank closures

    SciTech Connect

    Rowley, C.A.

    1993-08-01

    This report describes the removal/characterization actions concerning underground storage tanks (UST) at the 100-N Area. Included are 105-N-LFT, 182-N-1-DT, 182-N-2-DT, 182-N-3-DT, 100-N-SS-27, and 100-N-SS-28. The text of this report gives a summary of remedial activities. In addition, correspondence relating to UST closures can be found in Appendix B. Appendix C contains copies of Unusual Occurrence Reports, and validated sampling data results comprise Appendix D.

  5. Educación no formal

    NASA Astrophysics Data System (ADS)

    Tignanelli, H.

    Se comentan en esta comunicación, las principales contribuciones realizadas en el campo de la educación en astronomía en los niveles primario, secundario y terciario, como punto de partida para la discusión de la actual inserción de los contenidos astronómicos en los nuevos contenidos curriculares de la EGB - Educación General Básica- y Polimodal, de la Reforma Educativa. En particular, se discuten los alcances de la educación formal y no formal, su importancia para la capacitación de profesores y maestros, y perspectivas a futuro.

  6. A Detailed Chemical Kinetic Reaction Mechanism for n-Alkane Hydrocarbons from n-Octane to n-Hexadecane

    SciTech Connect

    Westbrook, C K; Pitz, W J; Herbinet, O; Silke, E J; Curran, H J

    2007-09-25

    Detailed chemical kinetic reaction mechanisms have been developed to describe the pyrolysis and oxidation of the n-alkanes, including n-octane (n-C{sub 8}H{sub 18}), n-nonane (n-C{sub 9}H{sub 20}), n-decane (n-C{sub 10}H{sub 22}), n-undecane (n-C{sub 11}H{sub 24}), n-dodecane (n-C{sub 12}H{sub 26}), n-tridecane (n-C{sub 13}H{sub 28}), n-tetradecane (n-C{sub 14}H{sub 30}), n-pentadecane (n-C{sub 15}H{sub 32}), and n-hexadecane (n-C{sub 16}H{sub 34}). These mechanisms include both high temperature and low temperature reaction pathways. The mechanisms are based on previous mechanisms for n-heptane, using the same reaction class mechanism construction developed initially for n-heptane. Individual reaction class rules are as simple as possible in order to focus on the parallelism between all of the n-alkane fuels included in the mechanisms, and there is an intent to develop these mechanisms further in the future to incorporate greater levels of accuracy and predictive capability. Several of these areas for improvement are identified and explained in detail. These mechanisms are validated through comparisons between computed and experimental data from as many different sources as possible. In addition, numerical experiments are carried out to examine features of n-alkane combustion in which the detailed mechanisms can be used to compare processes in all of the n-alkane fuels. The mechanisms for all of these n-alkanes are presented as a single detailed mechanism, which can be edited to produce efficient mechanisms for any of the n-alkanes included, and the entire mechanism, with supporting thermochemical and transport data, together with an explanatory glossary explaining notations and structural details, will be available on our web page when the paper is accepted for publication.

  7. More N =4 superconformal bootstrap

    NASA Astrophysics Data System (ADS)

    Beem, Christopher; Rastelli, Leonardo; van Rees, Balt C.

    2017-08-01

    In this long overdue second installment, we continue to develop the conformal bootstrap program for N =4 superconformal field theories (SCFTs) in four dimensions via an analysis of the correlation function of four stress-tensor supermultiplets. We review analytic results for this correlator and make contact with the SCFT/chiral algebra correspondence of Beem et al. [Commun. Math. Phys. 336, 1359 (2015), 10.1007/s00220-014-2272-x]. We demonstrate that the constraints of unitarity and crossing symmetry require the central charge c to be greater than or equal to 3 /4 in any interacting N =4 SCFT. We apply numerical bootstrap methods to derive upper bounds on scaling dimensions and operator product expansion coefficients for several low-lying, unprotected operators as a function of the central charge. We interpret our bounds in the context of N =4 super Yang-Mills theories, formulating a series of conjectures regarding the embedding of the conformal manifold—parametrized by the complexified gauge coupling—into the space of scaling dimensions and operator product expansion coefficients. Our conjectures assign a distinguished role to points on the conformal manifold that are self-dual under a subgroup of the S -duality group. This paper contains a more detailed exposition of a number of results previously reported in Beem et al. [Phys. Rev. Lett. 111, 071601 (2013), 10.1103/PhysRevLett.111.071601] in addition to new results.

  8. Quantum algebra of N superspace

    SciTech Connect

    Hatcher, Nicolas; Restuccia, A.; Stephany, J.

    2007-08-15

    We identify the quantum algebra of position and momentum operators for a quantum system bearing an irreducible representation of the super Poincare algebra in the N>1 and D=4 superspace, both in the case where there are no central charges in the algebra, and when they are present. This algebra is noncommutative for the position operators. We use the properties of superprojectors acting on the superfields to construct explicit position and momentum operators satisfying the algebra. They act on the projected wave functions associated to the various supermultiplets with defined superspin present in the representation. We show that the quantum algebra associated to the massive superparticle appears in our construction and is described by a supermultiplet of superspin 0. This result generalizes the construction for D=4, N=1 reported recently. For the case N=2 with central charges, we present the equivalent results when the central charge and the mass are different. For the {kappa}-symmetric case when these quantities are equal, we discuss the reduction to the physical degrees of freedom of the corresponding superparticle and the construction of the associated quantum algebra.

  9. N+CPT clock resonance

    SciTech Connect

    Crescimanno, M.; Hohensee, M.

    2008-12-15

    In a typical compact atomic time standard a current modulated semiconductor laser is used to create the optical fields that interrogate the atomic hyperfine transition. A pair of optical sidebands created by modulating the diode laser become the coherent population trapping (CPT) fields. At the same time, other pairs of optical sidebands may contribute to other multiphoton resonances, such as three-photon N-resonance [Phys. Rev. A 65, 043817 (2002)]. We analyze the resulting joint CPT and N-resonance (hereafter N+CPT) analytically and numerically. Analytically we solve a four-level quantum optics model for this joint resonance and perturbatively include the leading ac Stark effects from the five largest optical fields in the laser's modulation comb. Numerically we use a truncated Floquet solving routine that first symbolically develops the optical Bloch equations to a prescribed order of perturbation theory before evaluating. This numerical approach has, as input, the complete physical details of the first two excited-state manifolds of {sup 87}Rb. We test these theoretical approaches with experiments by characterizing the optimal clock operating regimes.

  10. Influence of InGaN sub-quantum-well on performance of InAlN/GaN/InAlN resonant tunneling diodes

    SciTech Connect

    Chen, Haoran; Yang, Lin'an Hao, Yue

    2014-08-21

    The resonant tunneling mechanism of the GaN based resonant tunneling diode (RTD) with an InGaN sub-quantum-well has been investigated by means of numerical simulation. At resonant-state, Electrons in the InGaN/InAlN/GaN/InAlN RTD tunnel from the emitter region through the aligned discrete energy levels in the InGaN sub-quantum-well and GaN main-quantum-well into the collector region. The implantation of the InGaN sub-quantum-well alters the dominant transport mechanism, increase the transmission coefficient and give rise to the peak current and peak-to-valley current ratio. We also demonstrate that the most pronounced negative-differential-resistance characteristic can be achieved by choosing appropriately the In composition of In{sub x}Ga{sub 1−x}N at around x = 0.06.

  11. Microcosm N2O emissions wth calibration

    EPA Pesticide Factsheets

    The dataset consists of measurements of soil nitrous oxide emissions from soils under three different amendments: glucose, cellulose, and manure. Data includes the four isotopomers of nitrous oxide (14N15N16O, 15N14N16O, 14N14N18O, 14N14N16O), and the site preference.This dataset is associated with the following publication:Chen , H., D. Williams , P. Deshmukh , F. Birgand, B. Maxwell, and J. Walker. Probing the Biological Sources of Soil N2O Emissions by Quantum Cascade Laser-Based 15N Isotopocule Analysis. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL. Soil Science Society of America, Madison, WI, USA, 100(0): 175-181, (2016).

  12. Mechanism of Carrier Transport in Hybrid GaN/AlN/Si Solar Cells

    NASA Astrophysics Data System (ADS)

    Ekinci, Huseyin; Kuryatkov, Vladimir V.; Gherasoiu, Iulian; Karpov, Sergey Y.; Nikishin, Sergey A.

    2017-05-01

    The particularities of the carrier transport in p-n-GaN/n-AlN/p-n-Si and n-GaN/n-AlN/p-n-Si structures were investigated through temperature-dependent current density and forward voltage (J-V) measurements, carrier distribution, and transport modeling. Despite the insulating properties of AlN, reasonably high current densities were achieved under forward bias. The experimental relationship between the current density and forward voltage was accurately approximated by an expression accounting for space-charge-limited current in the AlN layer and non-linear characteristics of the p-n junction formed in silicon. We suggest that extended defects throughout the AlN volume are responsible for the conduction, although the limited data available do not allow the accurate identification of the type of these defects.

  13. Mechanism of Carrier Transport in Hybrid GaN/AlN/Si Solar Cells

    NASA Astrophysics Data System (ADS)

    Ekinci, Huseyin; Kuryatkov, Vladimir V.; Gherasoiu, Iulian; Karpov, Sergey Y.; Nikishin, Sergey A.

    2017-10-01

    The particularities of the carrier transport in p- n-GaN/ n-AlN/ p- n-Si and n-GaN/ n-AlN /p- n-Si structures were investigated through temperature-dependent current density and forward voltage ( J- V) measurements, carrier distribution, and transport modeling. Despite the insulating properties of AlN, reasonably high current densities were achieved under forward bias. The experimental relationship between the current density and forward voltage was accurately approximated by an expression accounting for space-charge-limited current in the AlN layer and non-linear characteristics of the p- n junction formed in silicon. We suggest that extended defects throughout the AlN volume are responsible for the conduction, although the limited data available do not allow the accurate identification of the type of these defects.

  14. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    PubMed Central

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-01-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10–25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm. PMID:28294166

  15. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-03-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10-25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm.

  16. N=1 supersymmetric {beta}-functions

    SciTech Connect

    Jones, D. R. T.

    1997-06-15

    Recent results on three-loop, four-loop and large-N{sub f}{beta}-functions in supersymmetric gauge theories are summarised. It is argued that the O(1/N{sub f})-corrected form of {beta}{sub g} in SQCD is consistent with the existence of the conformal window 3N{sub c}/2<N{sub f}<3N{sub c}.

  17. Betavoltaic p--n+-structure simulation

    NASA Astrophysics Data System (ADS)

    Urchuk, S. U.; Murashev, V. N.; Legotin, S. A.; Krasnov, A. A.; Rabinovich, O. I.; Kuzmina, K. A.; Omel'chenko, Y. K.; Osipov, U. V.; Didenko, S. I.

    2016-08-01

    In order to increase the betavoltaic batteries efficiency output characteristics of the p--n+ (n--p+) - structures were simulated. Replacing the p+-n-structures on the p-n+ and n-p+ -structures enables the space-charge expansion to the crystal surface and thus to reduce the recombination loss in the heavy doped p+-layer and improve conversion of betavoltaic elements efficiency.

  18. Reflections on the "N" + "k" Queens Problem

    ERIC Educational Resources Information Center

    Chatham, Doug

    2009-01-01

    The "N" queens problem is a classic puzzle. It asks for an arrangement of "N" mutually non-attacking queens on an "N" x "N" chessboard. We discuss a recent variation called the "N" + "k" queens problem, where pawns are added to the chessboard to allow a greater number of non-attacking queens to be placed on it. We describe some of what is known…

  19. Reactions of ions in excited electronic states - Excited N2/+/ ion reacting with N2 to yield N3/+/ and N

    NASA Technical Reports Server (NTRS)

    Bowers, M. T.; Kemper, P. R.; Laudenslager, J. B.

    1974-01-01

    Study of the mechanism of formation of the N3(+) ion from the bimolecular reaction of excited N2(+) ions in gaseous N2. Using ion cyclotron resonance spectroscopy, an attempt is made to inquire more deeply than hitherto into the origin of the N3(+) ions and to determine the rate constant for their formation and the limits on the lifetime of the reactant excited N2(+) ions.

  20. Investigation of different mechanisms of GaN growth induced on AlN and GaN nucleation layers

    SciTech Connect

    Tasco, V.; Campa, A.; Tarantini, I.; Passaseo, A.; Gonzalez-Posada, F.; Munoz, E.; Redondo-Cubero, A.; Lorenz, K.; Franco, N.

    2009-03-15

    The evolution of GaN growth on AlN and GaN nucleation layers is compared through morphological and structural analyses, including ion beam analysis. By using AlN nucleation layer grown at high temperature, improved crystalline quality is exhibited by 300 nm thin GaN epilayers. GaN (002) x-ray rocking curve as narrow as 168 arc sec and atomic-step surface morphology characterize such a thin GaN film on AlN. Defects are strongly confined into the first 50 nm of growth, whereas a fast laterally coherent growth is observed when increasing thickness, as an effect of high temperature AlN surface morphology and Ga adatom dynamics over this template.

  1. Investigation of Gd3N@C2n (40 <= n <= 44) family by Raman and inelastic electron tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Burke, Brian; Chan, Jack; Williams, Keith; Ge, Jiechao; Shu, Chunying; Fu, Wujun; Dorn, Harry; Kushmerick, James; Puretzky, Alexander; Geohegan, David

    2010-03-01

    The structure and vibrational spectrum of Gd3N@C80 is studied through Raman and inelastic electron tunneling spectroscopy (IETS) as well as density functional theory (DFT) and universal force field (UFF) calculations. Hindered rotations, shown by both theory and experiment, indicate the formation of a Gd3N-C80 bond which reduces the ideal icosahedral symmetry of the C80 cage. The vibrational modes involving the movement of the encapsulated species are a fingerprint of the interaction between the fullerene cage and the core complex. We present Raman data for the Gd3N@C2n (40 <= n <= 44) family as well as Y3N@C80, Lu3N@C80, and Y3N@C88 for comparison. Conductance measurements have been performed on Gd3N@C80 and reveal a Kondo effect similar to that observed in C60.

  2. Nanoscale characterization of GaN/InGaN multiple quantum wells on GaN nanorods by photoluminescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Weijian; Wen, Xiaoming; Latzel, Michael; Yang, Jianfeng; Huang, Shujuan; Shrestha, Santosh; Patterson, Robert; Christiansen, Silke; Conibeer, Gavin

    2017-02-01

    GaN/InGaN multiple quantum wells (MQW) and GaN nanorods have been widely studied as a candidate material for high-performance light emitting diodes. In this study, GaN/InGaN MQW on top of GaN nanorods are characterized in nanoscale using confocal microscopy associated with photoluminescence spectroscopy, including steady-state PL, timeresolved PL and fluorescence lifetime imaging (FLIM). Nanorods are fabricated by etching planar GaN/InGaN MQWs on top of a GaN layer on a c-plane sapphire substrate. Photoluminescence efficiency from the GaN/InGaN nanorods is evidently higher than that of the planar structure, indicating the emission improvement. Time-resolved photoluminescence (TRPL) prove that surface defects on GaN nanorod sidewalls have a strong influence on the luminescence property of the GaN/InGaN MWQs. Such surface defects can be eliminated by proper surface passivation. Moreover, densely packed nanorod array and sparsely standing nanorods have been studied for better understanding the individual property and collective effects from adjacent nanorods. The combination of the optical characterization techniques guides optoelectronic materials and device fabrication.

  3. Elimination of surface band bending on N-polar InN with thin GaN capping

    SciTech Connect

    Kuzmík, J. Haščík, Š.; Kučera, M.; Kúdela, R.; Dobročka, E.; Adikimenakis, A.; Mičušík, M.; Gregor, M.; Plecenik, A.; Georgakilas, A.

    2015-11-09

    0.5–1 μm thick InN (0001) films grown by molecular-beam epitaxy with N- or In-polarity are investigated for the presence of native oxide, surface energy band bending, and effects introduced by 2 to 4 monolayers of GaN capping. Ex situ angle-resolved x-ray photo-electron spectroscopy is used to construct near-surface (GaN)/InN energy profiles, which is combined with deconvolution of In3d signal to trace the presence of InN native oxide for different types of polarity and capping. Downwards surface energy band bending was observed on bare samples with native oxide, regardless of the polarity. It was found that the In-polar InN surface is most readily oxidized, however, with only slightly less band bending if compared with the N-polar sample. On the other hand, InN surface oxidation was effectively mitigated by GaN capping. Still, as confirmed by ultra-violet photo-electron spectroscopy and by energy band diagram calculations, thin GaN cap layer may provide negative piezoelectric polarization charge at the GaN/InN hetero-interface of the N-polar sample, in addition to the passivation effect. These effects raised the band diagram up by about 0.65 eV, reaching a flat-band profile.

  4. Thermal stability of multilayer Ti2AlN-based ohmic contacts to n-GaN in ambient air

    NASA Astrophysics Data System (ADS)

    Borysiewicz, Michał A.; Myśliwiec, Marcin; Gołaszewska, Krystyna; Jakieła, Rafał; Dynowska, Elżbieta; Kamińska, Eliana; Piotrowska, Anna

    2014-04-01

    A multilayer Ti/Al/TiN/Ti/Al/TiN/Ti/Al/TiN metallization scheme is applied as an ohmic contact to n-GaN (n = 1017 cm-3). After formation of the contact through RTP at 600 °C for 6 min in Ar flow a Ti2AlN layer is created at the interface to n-GaN and Ti/Al layers form AlTi. The specific contact resistance of the as-formed contact is 7.4 × 10-4 Ω cm2. The contact remains ohmic and morphologically unaltered for annealing at 300 °C, 400 °C and 500 °C in ambient air for 100 h each and its resistivity rises to around 1.1 × 10-3 Ω cm2. This stability on one hand can be attributed to Ti2AlN MAX phase presence at the interface which inhibits excessive decomposition of GaN and thus confines the reaction between n-GaN and the metallization, and on the other to the presence of several TiN films in the metallization scheme, which are known to be diffusion barriers.

  5. Challenge of N95 Filtering Facepiece Respirators with Viable H1N1 Influenza Aerosols (Postprint)

    DTIC Science & Technology

    2013-05-01

    AFRL-RX-TY-TP-2012-0025 CHALLENGE OF N95 FILTERING FACEPIECE RESPIRATORS WITH VIABLE H1N1 INFLUENZA AEROSOLS (POSTPRINT) Joseph D...TITLE AND SUBTITLE CHALLENGE OF N95 FILTERING FACEPIECE RESPIRATORS WITH VIABLE H1N1 INFLUENZA AEROSOLS (POSTPRINT) 5a. CONTRACT NUMBER FA4819-10...study evaluates the ability of N95 FFRs to capture viable H1N1 influenza aerosols. METHODs. Five N95 FFR models were challenged with aerosolized

  6. Simultaneous determination of N-hydroxymethyl-N-methylformamide, N-methylformamide and N-acetyl-S-(N-methylcarbamoyl)cystein in urine samples from workers exposed to N,N-dimethylformamide by liquid chromatography-tandem mass spectrometry.

    PubMed

    Sohn, Jae Ho; Han, Min Jeong; Lee, Mi Young; Kang, Seong-Kyu; Yang, Jeong Sun

    2005-02-07

    N-Hydroxymethyl-N-methylformamide (HMMF) and N-methylformamide (NMF) in urine samples from workers exposed to N,N-dimethylformamide (DMF) cannot be distinguished by a gas chromatographic method because HMMF is converted to NMF at the injection port of gas chromatography (GC). Total NMF (HMMF+NMF) has been measured instead. Also, the determination of N-acetyl-S-(N-methylcarbamoyl)cystein (AMCC), which is supposed to be related to the toxicity of DMF, needs multiple treatments to convert to a volatile compound before GC analysis. There is no previous report of a simultaneous determination of three major metabolites of DMF in urine. The aim of this study is to develop a simple and selective method for the determination of DMF metabolite in urine. By using a liquid chromatography-tandem mass spectrometry, we can directly distinguish these three major metabolites of DMF in a single run. The diluted urine samples were analyzed on Capcell Pak MF SG80 column with the mobile phase of methanol in 2mM formic acid (10:90, v/v). The analytes were detected by an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curves were linear (r>0.999) over the concentration ranges of 0.004-8 microg/mL. The precision and accuracy of quality control samples for inter-batch (n=6) analyses were in the range of 1.3-9.8% and 94.7-116.8, respectively. The sum of each HMMF and NMF concentration determined by LC-MS/MS method shows high correlation (r=0.9927 with the slope of 1.0415, p<0.0001) with NMF included HMMF concentration determined by GC method for 13 urine samples taken from workers exposed to DMF. The excretion ratio of HMMF:NMF:AMCC is approximately 4:1:1 in molar concentration.

  7. A new ΛN --> N N weak potential and the hypernuclear nonmesonic decay

    NASA Astrophysics Data System (ADS)

    Itonaga, K.; Ueda, T.; Motoba, T.

    1994-09-01

    A new ΛN → NN weak potential which incorporates the isoscalar ″2 π/ σ″ meson exchange is proposed. This potential contains central, LS and parity-violating vector parts and it has no tensor interaction. The nonmesonic decay rates of Λ5He, Λ4He and Λ4H are evaluated with use of Vπ and V2 π/ σ potentials and are compared with the data.

  8. Surface donor states distribution post SiN passivation of AlGaN/GaN heterostructures

    SciTech Connect

    Goyal, Nitin; Fjeldly, Tor A.

    2014-07-21

    In this paper, we present a physics based analytical model to describe the effect of SiN passivation on two-dimensional electron gas density and surface barrier height in AlGaN/GaN heterostructures. The model is based on an extraction technique to calculate surface donor density and surface donor level at the SiN/AlGaN interface. The model is in good agreement with the experimental results and promises to become a useful tool in advanced design and characterization of GaN based heterostructures.

  9. AlGaN solar-blind avalanche photodiodes with AlInN/AlGaN distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Yao, Chujun; Ye, Xuanchao; Sun, Rui; Yang, Guofeng; Wang, Jin; Lu, Yanan; Yan, Pengfei; Cao, Jintao

    2017-06-01

    AlGaN solar-blind avalanche photodiodes (APDs) with AlInN/AlGaN distributed Bragg reflectors (DBRs) operated at lower avalanche breakdown voltage are numerically demonstrated. The p-type AlGaN layer and the multiplicative layer with low Al composition are introduced to construct the polarization-induced electric field, which can significantly reduce the avalanche breakdown voltage of the APDs. Calculated results exhibit that the avalanche breakdown voltage of the designed APDs decrease by 13% compared with the conventional device structure. Simultaneously, an improved solar-blind spectral responsivity is achieved due to the inserted AlInN/AlGaN DBRs.

  10. [Spatial Variation of Ammonia-N, Nitrate-N and Nitrite-N in Groundwater of Dongshan Island].

    PubMed

    Wiu, Hai-yan; Fu, Shi-feng; Cai, Xiao-qiong; Tang, Kun-xian; Cao, Chao; Chen, Qing-hui; Liang, Xiu-yu

    2015-09-01

    In Dongshan Island, groundwater is the main resource of the local residents' drinking water, domestic water, agriculture irrigation and freshwater aquaculture. This study aimed to investigate the spatial distribution characteristic and its variation pattern of ammonia-N, nitrate-N and nitrite-N in groundwater, as well as its pollution source and influence factors. It is very important to understand the pollution level of ammonia-N, nitrate-N and nitrite-N in groundwater of Dongshan Island, the control and prevention of ammonia-N, nitrate-N and nitrite-N pollution, which is of great significance to the residents' health. In this study, the spatial variability characteristics of ammonia-N, nitrate-N and nitrite-N concentration in groundwater of Dongshan Island was analysed by geo- statistic method, the values of the non-observation points were determined by Kriging method, and the pollution characteristics of ammonia-N, nitrate-N and nitrite-N in groundwater of Dongshan Island was also analyzed. Our results showed that the ammonia-N and nitrite-N concentration in groundwater of Dongshan Island were at low levels, but their spatial variability were high, and their autocorrelation were poor; however, the nitrate-N concentration was general high, its spatial variability was moderate, and the autocorrelation was much good. The distribution characteristics of ammonia-N, nitrate-N and nitrite-N in groundwater of Dongshan Island were similar that the high concentration areas were all located in the coastal land. The domestic pollutants and human and animal wastes from towns and villages were the main sources of nitrogen pollution, which would be the first step to control the nitrogen pollution of Dongshan Island. Land use pattern, soil type, groundwater depth, pH, dissolved oxygen, season, and the existence of Fe2+, were the impact factors that influence the distribution and transformation of ammonia-N, nitrate-N and nitrite-N in groundwater, which could be the considerable

  11. Comparative Study on Hole Transport in N, N'-bis(naphthalen-1-yl)-N,N'-bis(pheny) Benzidine and 4, 4', 4"-tri(N-carbazolyl)triphenylamine

    NASA Astrophysics Data System (ADS)

    Qiao, Xian-Feng; Chen, Jiang-Shan; Ma, Dong-Ge

    2010-08-01

    Hole transport characteristics in N,N'-bis(naphthalen-1-yl)-N,N'-bis(pheny) benzidine (NPB) and 4,4', 4"-tri(N-carbazolyl)triphenylamine (TCTA) are comparatively investigated. The current density-voltage (J - V) characteristics of hole-only devices based on NPB and TCTA at different temperatures and thicknesses show that the hole current is dominated by the bulk conduction with an exponential trap distribution. Detailed analyses of the J - V characteristics give the trap densities Nt of (6.3 ± 0.3) × 1018 and (1.9 ± 0.02) × 1018 cm3, characteristic trap depths of 135 ± 6 and 117 ± 5 meV, hole mobilities of (8.1 ± 0.5) × 10-5 and (1.9 ± 0.1) × 10-4 cm2 V-1 s-1 for NPB and TCTA, respectively. It is found that TCTA exhibits higher hole mobility. Obviously, this is directly related to the lower trap density and shallow trap depth in TCTA films, leading to good charge carrier transport.

  12. Systemic modulation by ultraviolet irradiation of cutaneous N-methyl-N'-nitro-N-nitrosoguanidine-induced carcinogenesis.

    PubMed

    Gensler, H L

    1992-01-10

    Ultraviolet irradiation can systemically enhance subsequent skin cancer induction by benzo[a]pyrene, methylcholanthrene, or UV radiation. The present study was designed to determine whether UVB irradiation influences host susceptibility to the alkylating agent N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Female C3H/HeJ mice were exposed dorsally to UVB radiation from banks of 6 Westinghouse FS40 sun lamps. The mice received a total UV dose of approximately 8.1 x 10(5) J m-2 over a 15-week period. After termination of UVB treatments, ventral tumors were induced by 4 applications of 30 mumol of MNNG at 8-day intervals. At 20 weeks after the first MNNG treatment, UVB-irradiated mice had 7-fold more MNNG-induced, ventral tumors than did the unirradiated control mice (P = 0.026, Wilcoxon rank sum test). Ventral application of MNNG after cessation of dorsal UVB exposure, but before UV tumor appearance, did not influence photocarcinogenesis. These results demonstrate that UV irradiation can systemically decrease host resistance to tumor induction by the methylating agent, MNNG.

  13. A first-principles study of Ni n Pd n (n = 1 - 5) clusters.

    PubMed

    Cervantes-Flores, Aldo; Cruz-Martínez, Heriberto; Solorza-Feria, Omar; Calaminici, Patrizia

    2017-05-01

    A first-principle investigation of structures and properties of Ni n Pd n (n=1-5) clusters is presented. For this study, the linear combination of Gaussian-type orbitals auxiliary density functional theory (LCGTO-ADFT) method has been employed. In order to determine the lowest energy structures, several isomers in different spin multiplicities were studied, for each cluster size. Initial structures, for which successive geometry optimization was computed without any constrain, were taken along Born-Oppenheimer molecular dynamics (BOMD) trajectories. To discriminate between minima and transition state structures, harmonic frequency analyses were performed at the optimized structures. Ground state structures, bond lengths, harmonic frequencies, dissociation energy, ionization potential, electron affinity and spin density plots are presented. This work demonstrates, that the Pd atoms prefer to allocate on the surface of the cluster structures whose core is formed by the 3d TM atoms type. Moreover, it has been observed that the ground-state structure spin multiplicity increases as the system size grows. The results of this study contribute to gain insight into how structures and energy properties change with cluster size in bimetallic Pd-based alloys.

  14. PMMA-N,N,N-trimethyl chitosan nanoparticles for fabrication of antibacterial natural rubber latex gloves.

    PubMed

    Arpornwichanop, Thanida; Polpanich, Duangporn; Thiramanas, Raweewan; Suteewong, Teeraporn; Tangboriboonrat, Pramuan

    2014-08-30

    This paper presents one-pot synthesis of N,N,N-trimethyl chitosan (TMC) stabilized poly(methyl methacrylate) (PMMA) latex particles via the miniemulsion polymerization technique. From (1)H NMR, synthesized TMC contains 52% degree of quaternization. Compared to native biopolymer chitosan, TMC possesses permanently positive charges as well as provides greater antibacterial activity. Combining properties of PMMA and TMC, PMMA-TMC latex nanoparticles (hydrodynamic size ≈282 nm) could be used in place of inorganic lubricating powder in fabrication of latex gloves at pH ≥ 7. After immersing sulphur prevulcanized natural rubber (SPNR) film into 3 wt% of PMMA-TMC latex at pH 7, significant amount of nanoparticles uniformly deposited onto SPNR film was observed under SEM. A number of nanoparticles present on film surface would increase surface roughness of the rubber film and potentially inhibit the bacterial (Escherichia coli and Staphylococcus aureus) growth, which would be useful for fabrication of special gloves with antibacterial property.

  15. Controlled synthesis of N,N,N-trimethyl chitosan for modulated bioadhesion and nasal membrane permeability.

    PubMed

    Pardeshi, Chandrakantsing V; Belgamwar, Veena S

    2016-01-01

    In an experiment to explore the bioadhesion, biocompatibility, and membrane permeation properties, the controlled synthesis of N,N,N-trimethyl chitosan (TMC) was carried out by two-step reductive methylation of chitosan (CHT). Methylation was confirmed by (1)H NMR (δ=3.1 ppm) and FTIR analysis (CH stretch at 1,485 cm(-1)). The TMC was further characterized by DSC, TGA, XRD, HR-TEM, SEM, and elemental analysis. Findings revealed improved solubility, enhanced viscosity, increased swelling index and higher molecular weight of TMC over CHT. Comparative evaluation validated increased bioadhesion potential, and improved ex vivo biocompatibility of TMC compared to CHT. Increased bioadhesion of TMC NPs over CHT NPs can be attributed to the strong electrostatic interactions between cationic amino groups with anionic sialic and sulfonic acid moieties contained in the mucin of the nasal mucus. Ex vivo biocompatibility studies suggested that the NP formulations of both biopolymers were biocompatible and could be applied safely on the nasal epithelium. Ex vivo permeation studies executed on excised cattle nasal mucosa illustrated improved permeability of TMC NPs over CHT NPs. In the author's opinion, two-step reductive methylation of CHT could be an attractive strategy to improve its solubility, bioadhesion, and permeation characteristics without affecting biocompatibility across the mucosal surfaces.

  16. Bioconjugation of quantum-dots with chitosan and N,N,N-trimethyl chitosan.

    PubMed

    Mansur, Herman S; Mansur, Alexandra A P; Curti, Elisabete; De Almeida, Mauro V

    2012-09-01

    Novel carbohydrate-based hybrids combining chitosan and chemically modified chitosan with CdS inorganic nanoparticles were designed and prepared via aqueous route at room temperature. N,N,N-trimethylchitosan (TM-chitosan) was synthesized aiming at substantially improving the water solubility of chitosan for producing stable colloidal systems. UV-vis spectroscopy, photoluminescence spectroscopy, Nuclear magnetic resonance spectroscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the synthesis and the relative stability of biopolymer-capped CdS nanocrystals. The results have clearly indicated that chitosan and chitosan-derivative (TM-chitosan) were remarkably effective on nucleating and stabilizing CdS nanoparticles in aqueous suspensions. In addition, the CdS nanocrystals were produced in the so-called "quantum-size confinement regime", with the calculated average size below 3.5 nm and fluorescent activity in the visible range of the spectra. Therefore, a new single-step process was developed for the bioconjugation of quantum dots with water soluble chemically functionalized carbohydrates at room temperature for potential biomedical applications.

  17. Mechanisms of intestinal absorption of the carcinogen MNNG (N-Methyl-N'-nitro-N-nitrosoguanidine)

    SciTech Connect

    Koyama, S.Y.; Hollander, D.; Dadufalza, V.

    1988-06-01

    The authors studied the characteristics and mechanisms of MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) intestinal absorption and the interaction between bile acids and fatty acids and MNNG absorption rat in vivo in male Sprague-Dawley rats. They found that MNNG was absorbed by simple passive diffusion. Transport of MNNG was the highest at pH 6.0. The addition of the bile salt, taurocholate by itself, greatly increased MNNG absorption, while the addition of the long-chain unsaturated fatty acids, oleic and linoleic, decreased the rate of absorption of MNNG. The phospholipid lecithin addition to the perfusate did not change the rate of MNNG absorption. Induction of dietary vitamin A deficiency (serum vitamin A level decreased from 40.9 to 13.7 ..mu..g/dl) did not change the absorption rate of MNNG. These studies demonstrate that bile acids, dietary fatty acids, and the pH of the intestinal content can modify the rate of absorption of this carcinogen by the small intestine. Since initial intestinal absorption determines serum levels and subsequent reabsorption and enterohepatic cycling determines long-term lumenal levels, serum levels, and total body content, factors which modify the rate of intestinal absorption of MNNG could also modify its carcinogenicity.

  18. Is N,N-dimethylglycine N-oxide a choline and betaine metabolite?

    PubMed

    Lever, Michael; McEntyre, Christopher J; George, Peter M; Chambers, Stephen T

    2017-06-27

    Choline metabolism is by oxidation to betaine, which is demethylated to N,N-dimethylglycine; dimethylglycine is oxidatively demethylated to sarcosine. This pathway is important for osmoregulation and as a source of methyl groups. We asked whether another metabolite was involved. We synthesized the N-oxide of dimethylglycine (DMGO) by oxidizing dimethylglycine with peracetic acid, and measured DMGO in human plasma and urine by HPLC-MS/MS with positive ion detection, using two chromatography procedures, based on ion exchange and HILIC separations. The molecular ion DMGOH+ (m/z=120) yielded four significant fragments (m/z=103, 102, 58 and 42). The suspected DMGO peak in human body fluids showed all these fragments, and co-chromatographed with added standard DMGO in both HPLC systems. Typical plasma concentrations of DMGO are under 1 μmol/l. They may be lower in metabolic syndrome patients. Urine concentrations are higher, and DMGO has a higher fractional clearance than dimethylglycine, betaine and choline. It was present in all of over 80 human urine and plasma samples assayed. Plasma DMGO concentrations correlate with plasma DMG concentrations, with betaine and choline concentrations, with the osmolyte myo-inositol, and strongly with urinary DMGO excretion. We conclude that DMGO is probably a normal human metabolite.

  19. A New Heterotrophic Cryptomonad: Hemiarma marina n. g., n. sp.

    PubMed

    Shiratori, Takashi; Ishida, Ken-Ichiro

    2016-11-01

    We report a new heterotrophic cryptomonad Hemiarma marina n. g., n. sp. that was collected from a seaweed sample from the Republic of Palau. In our molecular phylogenetic analyses using the small subunit ribosomal RNA gene, H. marina formed a clade with two marine environmental sequences, and the clade was placed as a sister lineage of the freshwater cryptomonad environmental clade CRY1. Alternatively, in the concatenated large and small subunit ribosomal RNA gene phylogeny, H. marina was placed as a sister lineage of Goniomonas. Light and electron microscopic observations showed that H. marina shares several ultrastructural features with cryptomonads, such as flattened mitochondrial cristae, a periplast cell covering, and ejectisomes that consist of two coiled ribbon structures. On the other hand, H. marina exhibited unique behaviors, such as attaching to substrates with its posterior flagellum and displaying a jumping motion. H. marina also had unique periplast arrangement and flagellar transitional region. On the basis of both molecular and morphological information, we concluded that H. marina should be treated as new genus and species of cryptomonads. © 2016 The Author(s) Journal of Eukaryotic Microbiology © 2016 International Society of Protistologists.

  20. Reactive Resonances in N+N2 Exchange Reaction

    NASA Technical Reports Server (NTRS)

    Wang, Dunyou; Huo, Winifred M.; Dateo, Christopher E.; Schwenke, David W.; Stallcop, James R.

    2003-01-01

    Rich reactive resonances are found in a 3D quantum dynamics study of the N + N2 exchange reaction using a recently developed ab initio potential energy surface. This surface is characterized by a feature in the interaction region called Lake Eyring , that is, two symmetric transition states with a shallow minimum between them. An L2 analysis of the quasibound states associated with the shallow minimum confirms that the quasibound states associated with oscillations in all three degrees of freedom in Lake Eyring are responsible for the reactive resonances in the state-to-state reaction probabilities. The quasibound states, mostly the bending motions, give rise to strong reasonance peaks, whereas other motions contribute to the bumps and shoulders in the resonance structure. The initial state reaction probability further proves that the bending motions are the dominating factors of the reaction probability and have longer life times than the stretching motions. This is the first observation of reactive resonances from a "Lake Eyring" feature in a potential energy surface.

  1. AlGaN/InGaN Photocathode Development

    SciTech Connect

    Buckley, J. H.; Leopold, D. J.

    2008-12-24

    An increase in quantum efficiency in photodetectors could result in a proportional reduction in the area of atmospheric Cherenkov telescopes and an even larger reduction in cost. We report on the development of high quantum efficiency, high gain, UV/blue photon-counting detectors based on AlGaN/InGaN photocathode heterostructures grown by molecular beam epitaxy. This research could eventually result in nearly ideal light detectors with a number of distinct advantages over existing technologies for numerous applications in high-energy physics and particle astrophysics. Potential advantages include much lower noise detection, better stability and radiation resistance than other cathode structures, high VUV sensitivity and very low radioactive background levels for deep underground experiments, and high detection efficiency for the detection of individual VUV-visible photons. We are also developing photocathodes with intrinsic gain, initially improving the detection efficiency of hybrid semiconductor-vacuum tube devices and eventually leading to a new type of all-solid-state photomultiplier device.

  2. Description of Quercorhabditis rajouriensis gen. n., sp. n. (Nematoda: Rhabditidae).

    PubMed

    Shah, Ali Asghar; Hussain, Abid; Vaid, Shavish

    2013-01-01

    Quercorhabditis rajouriensis gen. n., sp. n. is described and illustrated. Distinctive characters include a labial region set off by a constriction and wider than adjoining body, heavily sclerotized cheilostom with arched rhabdions, barely differentiable stegostom, amphidelphic gonads, spicules with a free dorsal arm, and a leptoderan bursa with ten pairs of bursal papillae. The new genus resembles Diploscapteriodes Rahm, 1928 in the shape of cheilostom, presence of amphidelphic gonads, leptoderan bursa and long conoid tail. However, it can be differentiated from the latter genus in the shape of labial region, cheilostomal sclerotization, absence of ridge-like tooth in gymnostom, having spicules with a free dorsal arm, somewhat boat-shaped gubernaculum and in having ten pairs of bursal papillae. The new genus also resembles Curviditis (Dougherty, 1953) Andrássy, 1983, Rhabditella (Cobb, 1929) Chitwood, 1933 and Metarhabditis Tahseen et. al., 2004 in having spicules with free dorsal arm. However, it can be differentiated from these related genera by its heavily cuticularised cheilostom with arched rhabdions and barely differentiable stegostom. The new genus can further be differentiated from Curviditis and Rhabditella in having a well developed bursa and from Metarhabditis by its leptoderan bursa with ten pairs of bursal papillae arranged in 3+4+3 arrangement.

  3. Nitrogen input 15N-signatures are reflected in plant 15N natural abundances of N-rich tropical forest in China

    NASA Astrophysics Data System (ADS)

    Abdisa Gurmesa, Geshere; Lu, Xiankai; Gundersen, Per; Yunting, Fang; Mo, Jiangming

    2016-04-01

    In this study, we tested the measurement of natural abundance of 15N (δ15N) for its ability to assess changes in N cycling due to increased N deposition in two forest types; namely, an old-growth broadleaved forest and a pine forest, in southern China. We measured δ15N values of inorganic N in input and output fluxes under ambient N deposition, and N concentration and δ15N of major ecosystem compartments under ambient and increased N deposition. Our results showed that N deposition to the forests was 15N-depleted, and was dominated by NH4-N. Plants were 15N-depleted due to imprint from the 15N-depleted atmospheric N deposition. The old-growth forest had larger N concentration and was more 15N-enriched than the pine forest. Nitrogen addition did not significantly affect N concentration, but it significantly increased δ15N values of plants, and slightly more so in the pine forest, toward the 15N signature of the added N in both forests. The result indicates that the pine forest may rely more on the 15N-depleted deposition N. Soil δ15N values were slightly decreased by the N addition. Our result suggests that ecosystem δ15N is more sensitive to the changes in ecosystem N status and N cycling than N concentration in N-saturated sub-tropical forests.

  4. AlGaN-Cladding-Free m-Plane InGaN/GaN Laser Diodes with p-Type AlGaN Etch Stop Layers

    NASA Astrophysics Data System (ADS)

    Farrell, Robert M.; Haeger, Daniel A.; Hsu, Po Shan; Hardy, Matthew T.; Kelchner, Kathryn M.; Fujito, Kenji; Feezell, Daniel F.; Mishra, Umesh K.; DenBaars, Steven P.; Speck, James S.; Nakamura, Shuji

    2011-09-01

    We present a new method of improving the accuracy and reproducibility of dry etching processes for ridge waveguide InGaN/GaN laser diodes (LDs). A GaN:Al0.09Ga0.91N etch rate selectivity of 11:1 was demonstrated for an m-plane LD with a 40 nm p-Al0.09Ga0.91N etch stop layer (ESL) surrounded by Al-free cladding layers, establishing the effectiveness of AlGaN-based ESLs for controlling etch depth in ridge waveguide InGaN/GaN LDs. These results demonstrate the potential for integrating AlGaN ESLs into commercial device designs where accurate control of the etch depth of the ridge waveguide is necessary for stable, kink-free operation at high output powers.

  5. Ntrace a 15N tracing model to analyse gross N transformations and sources of gaseous N emissions

    NASA Astrophysics Data System (ADS)

    Muller, Christoph

    2013-04-01

    Anthropogenically generated reactive nitrogen (N) cascades throughout the global environment ...(Galloway and Cowling, 2002). This reactive N may be lost from ecosystems via leaching, as nitrate (NO3-), or in gaseous forms such as ammonia and nitrous oxide (N2O) and the loss is governed by the N dynamics of the system. Thus, to be rendered environmentally benign NO3- must be reduced to a non-reactive form, dinitrogen (N2) which requires the evaluation of three major biological pathways of NO3- reduction: i) assimilatory NO3- reduction into biomass, ii) dissimilatory NO3- reduction to NH4+ (DNRA) and iii) dissimilatory NO3- reduction to N2 (denitrification) ...(Burger and Jackson, 2004). Advanced techniques based on 15N tracing in combination with suitable model analyses are the method of choice to analyse complex N interactions and simultaneous N transformation process. Techniques are based on dilution - enrichment principles and usually rely on the simultaneous labelling of various N pools. The data sets are then analysed by suitable 15N tracing models which allow the individual N transformation rates to be calculated based on realistic kinetic settings. The 15N tracing model Ntrace has been developed to analyse the simultaneously occurring N transformation rates in soil-plant systems and includes submodels for the evaluation of the processes associated with gaseous N emissions. The 15N tracing model and some typical model results will be presented. Literature cited .Burger, M., and Jackson, L. E. (2004). Plant and microbial use and turnover: rapid conversion of nitrate to ammonium in soil with roots. Plant and Soil 266, 289-301. Galloway, J. N., and Cowling, E. B. (2002). Reactive nitrogen and the world: 200 years of change. Ambio 31, 64-71. .

  6. A taxonomic revision of Neoserica (sensu lato): the species groups N. lubrica, N. obscura, and N. silvestris (Coleoptera, Scarabaeidae, Sericini)

    PubMed Central

    Liu, Wan-Gang; Fabrizi, Silvia; Bai, Ming; Ahrens, Dirk

    2016-01-01

    Abstract The species of the Neoserica lubrica Brenske, 1898, Neoserica obscura (Blanchard, 1850) and Neoserica silvestris Brenske, 1902 species groups are revised. The study resulted in the following new synonymies and combinations: Neoserica obscura (Blanchard, 1850) = Microserica roeri Frey, 1972, syn. n., = Maladera chinensis (Arrow, 1946), syn. n.; Neoserica hainana (Brenske, 1898), comb. n., and Neoserica minor (Arrow, 1946), comb. n. The known species are redescribed. The following nine new species are described from China: Neoserica allobscura Ahrens, Fabrizi & Liu, sp. n., Neoserica dongjiafenensis Ahrens, Fabrizi & Liu, sp. n., Neoserica fugongensis Ahrens, Fabrizi & Liu, sp. n., Neoserica mantillerii Ahrens, Fabrizi & Liu, sp. n., Neoserica menglunensis Ahrens, Fabrizi & Liu, sp. n., Neoserica pseudosilvestris Ahrens, Fabrizi & Liu, sp. n., Neoserica sakoliana Ahrens, Fabrizi & Liu, sp. n., Neoserica shuyongi Ahrens, Fabrizi & Liu, sp. n., and Neoserica tahianensis Ahrens, Fabrizi & Liu, sp. n. A key to the Sericini genera with multilamellate antenna, species groups of Neoserica of mainland Asia, and species of the species groups examined here are provided. Maps of the species distribution are provided, habitus and male genitalia are illustrated. PMID:27917061

  7. HVPE-GaN growth on GaN-based Advanced Substrates by Smart Cut™

    NASA Astrophysics Data System (ADS)

    Iwinska, M.; Amilusik, M.; Fijalkowski, M.; Sochacki, T.; Lucznik, B.; Grzanka, E.; Litwin-Staszewska, E.; Weyher, J. L.; Nowakowska-Siwinska, A.; Muziol, G.; Skierbiszewski, C.; Grzegory, I.; Guiot, E.; Caulmilone, R.; Bockowski, M.

    2016-12-01

    Advanced Substrates consist of a thin GaN layer bonded to a carrier wafer. The layer is separated from starting material by Smart Cut™ technology. GaN on sapphire Advanced Substrates were successfully used as seeds for HVPE-GaN growth. Unintentionally doped and silicon-doped thick GaN layers were crystallized. The results were compared to HVPE-GaN grown on standard MOCVD-GaN/sapphire templates. Free-standing HVPE-GaN with high free carrier concentration was obtained. A laser diode was built on the n-type doped HVPE-GaN grown on an Advanced Substrate.

  8. Clasificación orbital

    NASA Astrophysics Data System (ADS)

    Carpintero, D. D.; Aguilar, L. A.

    Presentamos un método para clasificar órbitas generales en potenciales de 2 y 3 dimensiones, basado en el concepto de dinámica espectral introducido por Binney y Spergel (ApJ 252, 308, 1982). Este método distingue correctamente órbitas regulares e irregulares, familias de órbitas (cajas, tubos, etc.), y resonancias, aún cuando son de alto orden o de rango mayor que 1. Se propone asimismo una nueva nomenclatura para la clasificación de órbitas.

  9. The N456 Navigator System

    DTIC Science & Technology

    2009-01-01

    system, the N456 timing functions are not used or affected. – 4 – 5. PRV Mode This is a common navigation method for the Jason/ Medea system. In...this mode, a trigger is sent down the tether, where it is causes an interrogation pulse from Medea . Boards dedicated to Medea and Jason both time the... Medea uses PING_BOARD=2 # MODE_CYCLE = the name of a ping cycle definition # IS_TIMED = 0 if pings occur at the commanded instant

  10. Bulk ammonothermal GaN

    NASA Astrophysics Data System (ADS)

    Dwiliński, R.; Doradziński, R.; Garczyński, J.; Sierzputowski, L. P.; Puchalski, A.; Kanbara, Y.; Yagi, K.; Minakuchi, H.; Hayashi, H.

    2009-05-01

    In this work, results of structural characterization of high-quality ammonothermal GaN are presented. Besides expected low dislocation density (being of the order of 10 3 cm -2) the most interesting feature seems perfect flatness of the crystal lattice of studied crystals. Regardless the size of crystals, lattice curvature radius exceeds 100 m, whereas better crystals reveal radius of several hundred meters and the best above 1000 m. Excellent crystallinity manifests in very narrow X-ray diffraction peaks of full-width at half-maximum (FWHM) values about 16 arcsec.

  11. Variation in internal N efficiency of maize and impact on yield-goal based N recommendations

    USDA-ARS?s Scientific Manuscript database

    Internal N efficiency (IE) is defined as grain dry matter (DM) produced per unit of N in the above-ground plant at physiological maturity (R6). Internal N efficiency defines the target for plant N content at R6 in yield-goal based N rate recommendations (currently used in 30 U.S. states) and several...

  12. 40 CFR Table 1 to Subpart N of... - General Provisions Applicability to Subpart N

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Subpart N 1 Table 1 to Subpart N of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Electroplating and Chromium Anodizing Tanks Pt. 63, Subpt. N, Table 1 Table 1 to Subpart N of Part 63—General...) No § 63.347(g) and (h) of subpart N specify the frequency of periodic reports of monitoring data used...

  13. Regional assessment of N saturation using foliar and root δ15N

    Treesearch

    L.H. Pardo; P.H. Templer; C.L. Goodale; S. Duke; P.M. Groffman; M.B. Adams; P. Boeckx; J. Boggs; J. Campbell; B. Colman; J. Compton; B. Emmett; P. Gundersen; J. Kjonaas; G. Lovett; M. Mack; A. Magill; M. Mbila; M.J. Mitchell; G. McGee; S. McNulty; K. Nadelhoffer; S. Ollinger; D. Ross; H. Rueth; L. Rustad; P. Schaberg; S. Schiff; P. Schleppi; J. Spoelstra; W. Wessel

    2006-01-01

    N saturation induced by atmospheric N deposition can have serious consequences for forest health in many regions. In order to evaluate whether foliar δ15N may be a robust, regional-scale measure of the onset of N saturation in forest ecosystems, we assembled a large dataset on atmospheric N deposition, foliar and root δ

  14. 40 CFR 721.225 - 2-Chloro-N-methyl-N-substituted acetamide (generic name).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false 2-Chloro-N-methyl-N-substituted... Specific Chemical Substances § 721.225 2-Chloro-N-methyl-N-substituted acetamide (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance 2-chloro-N...

  15. 40 CFR 721.225 - 2-Chloro-N-methyl-N-substituted acetamide (generic name).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false 2-Chloro-N-methyl-N-substituted... Specific Chemical Substances § 721.225 2-Chloro-N-methyl-N-substituted acetamide (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance 2-chloro-N...

  16. 40 CFR 721.225 - 2-Chloro-N-methyl-N-substituted acetamide (generic name).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false 2-Chloro-N-methyl-N-substituted... Specific Chemical Substances § 721.225 2-Chloro-N-methyl-N-substituted acetamide (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance 2-chloro-N...

  17. Eta(') mass and chiral symmetry breaking at large N(c) and N(f).

    PubMed

    Girlanda, L; Stern, J; Talavera, P

    2001-06-25

    We propose a method for implementing the large- N(c), large-N(f) limit of QCD at the effective Lagrangian level. Depending on the value of the ratio N(f)/N(c), different patterns of chiral symmetry breaking can arise, leading in particular to different behaviors of the eta(') mass in the combined large-N limit.

  18. 40 CFR 721.225 - 2-Chloro-N-methyl-N-substituted acetamide (generic name).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false 2-Chloro-N-methyl-N-substituted... Specific Chemical Substances § 721.225 2-Chloro-N-methyl-N-substituted acetamide (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance 2-chloro-N...

  19. Quantifying N2O reduction to N2 based on N2O isotopocules - validation with independent methods (helium incubation and 15N gas flux method)

    NASA Astrophysics Data System (ADS)

    Lewicka-Szczebak, Dominika; Augustin, Jürgen; Giesemann, Anette; Well, Reinhard

    2017-02-01

    Stable isotopic analyses of soil-emitted N2O (δ15Nbulk, δ18O and δ15Nsp = 15N site preference within the linear N2O molecule) may help to quantify N2O reduction to N2, an important but rarely quantified process in the soil nitrogen cycle. The N2O residual fraction (remaining unreduced N2O, rN2O) can be theoretically calculated from the measured isotopic enrichment of the residual N2O. However, various N2O-producing pathways may also influence the N2O isotopic signatures, and hence complicate the application of this isotopic fractionation approach. Here this approach was tested based on laboratory soil incubations with two different soil types, applying two reference methods for quantification of rN2O: helium incubation with direct measurement of N2 flux and the 15N gas flux method. This allowed a comparison of the measured rN2O values with the ones calculated based on isotopic enrichment of residual N2O. The results indicate that the performance of the N2O isotopic fractionation approach is related to the accompanying N2O and N2 source processes and the most critical is the determination of the initial isotopic signature of N2O before reduction (δ0). We show that δ0 can be well determined experimentally if stable in time and then successfully applied for determination of rN2O based on δ15Nsp values. Much more problematic to deal with are temporal changes of δ0 values leading to failure of the approach based on δ15Nsp values only. For this case, we propose here a dual N2O isotopocule mapping approach, where calculations are based on the relation between δ18O and δ15Nsp values. This allows for the simultaneous estimation of the N2O-producing pathways' contribution and the rN2O value.

  20. Physics of gate leakage current in N-polar InAlN/GaN heterojunction field effect transistors

    SciTech Connect

    Goswami, Arunesh; Trew, Robert J.; Bilbro, Griff L.

    2014-10-28

    A physics based model of the gate leakage current in N-polar InAlN/GaN heterojunction field effect transistors is demonstrated. The model is based on the space charge limited current flow dominated by the effects of deep traps in the InAlN surface layer. The model predicts accurately the gate-leakage measurement data of the N-polar InAlN/GaN device with InAlN cap layer. In the pinch-off state, the gate leakage current conduction through the surface of the device in the drain access region dominates the current flow through the two dimensional electron gas channel. One deep trap level and two levels of shallow traps are extracted by fitting the model results with measurement data.

  1. Tests of N-85, N-86 and N-87 airfoil sections in the 11-inch high speed wind tunnel

    NASA Technical Reports Server (NTRS)

    Stack, John; Lindsey, W F

    1938-01-01

    Three airfoils, the N-85, the N-86, and the N-87, were tested at the request of the Bureau of Aeronautics, Navy Department, to determine the suitability of these sections for use as propeller-blade sections. Further tests of the NACA 0009-64 airfoil were also made to measure the aerodynamic effect of thickening the trailing edge in accordance with current propeller practice. The N-86 and the N-87 airfoils appear to be nearly equivalent aerodynamically and both are superior to the N-85 airfoil. Comparison of those airfoils with the previously developed NACA 2409-34 airfoils indicate that the NACA 2409-34 is superior, particularly at high speeds. Thickening the trailing edge appears to have a detrimental effect, although the effect may be small if the trailing-edge radius is less than 0.5 percent of the cord. The N-86 and the N-87 airfoils appear to be nearly equivalent.

  2. Electroluminescence from InGaN quantum dots in a fully monolithic GaN/AlInN cavity

    NASA Astrophysics Data System (ADS)

    Dartsch, Heiko; Tessarek, Christian; Aschenbrenner, Timo; Figge, Stephan; Kruse, Carsten; Schowalter, Marco; Rosenauer, Andreas; Hommel, Detlef

    2011-04-01

    We present for the first time electroluminescence from InGaN quantum dots inside a monolithic nitride based cavity. The structure consists of a 40-fold bottom GaN/Al 0.82In 0.18N distributed Bragg reflector (DBR), a single InGaN quantum dot layer inside a 5λ n-type (bottom) and p-type (top) doped GaN cavity and a 10-fold GaN/Al 0.82In 0.18N top DBR. Structural properties have been investigated by scanning transmission electron microscopy. Optical reflectivity measurements are in good agreement with calculations which predict a peak reflectivity of 92% and a quality factor of 220. Electroluminescence shows a pronounced emission at the spectral position of the cavity mode near 500 nm.

  3. Electrically conducting n-type AlGaN/GaN distributed Bragg reflectors grown by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Liu, Yuh-Shiuan; Haq, A. F. M. Saniul; Kao, Tsung-Ting; Mehta, Karan; Shen, Shyh-Chiang; Detchprohm, Theeradetch; Yoder, P. Douglas; Dupuis, Russell D.; Xie, Hongen; Ponce, Fernando A.

    2016-06-01

    We report an electrically conducting 40-pair silicon doped Al0.12Ga0.88N/GaN distributed Bragg reflector (DBR) grown by metalorganic chemical vapor deposition on a silicon doped n-type GaN template. Due to the relatively small lattice mismatch between AlGaN and GaN, strain managing layers are not required for crack-free n-DBR growth. The DBR demonstrates a peak reflectivity of 91.6% at 368 nm with stopband of 11 nm. In addition, the 40-pair n-DBR shows the vertical resistance of 5.5 Ω, which corresponds to bulk resistivity of 0.52 Ω cm, near the maximum measured current of 100 mA.

  4. [Effects of urease/nitrification inhibitors on soil available N and microbial biomass N and on N uptake of wheat].

    PubMed

    Jiao, Xiaoguang; Liang, Wenju; Chen, Lijun; Jiang, Yong; Wen, Dazhong

    2004-10-01

    With an aquic brown earth as test soil, this paper studied the effects of urease inhibitor (NBPT), nitrification inhibitor (DCD) and their combinations on the dynamics of soil available N and microbial biomass N. The results showed that the treatments of inhibitors, especially the combined application of NBPT and DCD, could increase soil NH4+-N by 2%-53%, inhibit NH4+ oxidation, decrease soil NO3(-)-N concentration, increase soil total available N by 34%-44%, and increase wheat N uptake by 0.26%-6.79%. The best treatment was urease inhibitor combined with nitrification inhibitor. The application of inhibitors increased soil microbial biomass N immobilization at the early growth stage of wheat, and promoted soil N mineralization at filling stage.

  5. N(7)-protonation-induced conformational flipping in hypermodified nucleic acid base N 6-(N-glycylcarbonyl) adenine

    NASA Astrophysics Data System (ADS)

    Tewari, Ravindra

    1995-06-01

    Protonation-induced conformational changes are studied in the hypermodified nucleic acid base N 6-(N-glycylcarbonyl) adenine, gc 6Ade, using the quantum chemical perturbative configuration interaction using localised orbitals method. Protonation at the N(7) position of adenine in gc 6Ade induces reorientation of the N 6 substituent, so as to allow stabilisation through an intramolecular hydrogen bond involving N(7)H and the carbonyl oxygen in the glycylcarbonyl substituent. The relative orientation of the carboxyl group with respect to the carbonyl group in the ureido HNCONH linkage is predicted to be similar to that in unprotonated gc 6Ade. The theoretically preferred proximal conformation of N(7)-protonated gc 6Ade restores the participation of N(6)H and N(1) in the Watson-Crick base pairing similar to that in unmodified adenine. This unique orientation can be significant for altering the reading frame in codon-anticodon interactions.

  6. Step-flow growth mode instability of N-polar GaN under N-excess

    SciTech Connect

    Chèze, C.

    2013-08-12

    GaN layers were grown on N-polar GaN substrates by plasma-assisted molecular beam epitaxy under different III/V ratios. Ga-rich conditions assure step-flow growth with atomically flat surface covered by doubly-bunched steps, as for Ga-polar GaN. Growth under N-excess however leads to an unstable step-flow morphology. Particularly, for substrates slightly miscut towards <1010>, interlacing fingers are covered by atomic steps pinned on both sides by small hexagonal pits. In contrast, a three-dimensional island morphology is observed on the Ga-polar equivalent sample. We attribute this result to lower diffusion barriers on N-polar compared to Ga-polar GaN under N-rich conditions.

  7. N2H+ and N15NH+ toward the prestellar core 16293E in L1689N

    NASA Astrophysics Data System (ADS)

    Daniel, F.; Faure, A.; Pagani, L.; Lique, F.; Gérin, M.; Lis, D.; Hily-Blant, P.; Bacmann, A.; Roueff, E.

    2016-07-01

    Context. Understanding the processes that could lead to an enrichment of molecules in 15N atoms is of particular interest because this may shed light on the relatively strong variations observed in the 14N/15N ratio in various solar system environments. Aims: The sample of molecular clouds where 14N/15N ratios have been measured currently is small and has to be enlarged to allow statistically significant studies. In particular, the N2H+ molecule currently shows the broadest spread of 14N/15N ratios in high-mass star-forming regions. However, the 14N/15N ratio in N2H+ was obtained in only two low-mass star-forming regions (L1544 and B1b). We here extend this sample to a third dark cloud. Methods: We targeted the 16293E prestellar core, where the N15NH+J = 1-0 line was detected. Using a model previously developed for the physical structure of the source, we solved the molecular excitation with a nonlocal radiative transfer code. For this purpose, we computed specific collisional rate coefficients for the N15NH+-H2 collisional system. As a first step of the analysis, the N2H+ abundance profile was constrained by reproducing the N2H+J = 1-0 and 3-2 maps. A scaling factor was then applied to this profile to match the N15NH+J = 1-0 spectrum. Results: We derive a column density ratio N2H+/N15NH. Conclusions: We performed a detailed analysis of the excitation of N2H+ and N15NH+ in the direction of the 16293E core with modern models that solve the radiative transfer and with the most accurate collisional rate coefficients available to date. We obtained the third estimate of the N2H+/N15NH+ column density ratio in the direction of a cold prestellar core. The current estimate ~330 agrees with the typical value of the elemental isotopic ratio in the local interstellar medium. It is lower than in some other cores, however, where values as high as 1300 have been reported.

  8. N'-[5-(4-Nitro-phen-yl)furan-2-yl-methyl-idene]-N,N-diphenyl-hydrazine.

    PubMed

    Mendoza, Angel; Cabrera-Vivas, Blanca M; Meléndrez-Luevano, Ruth; Pacheco-Álvarez, Teresa; Carranza, Vladimir

    2010-07-17

    The title compound, C(23)H(17)N(3)O(3), has an E configuration with respect to the C=N bond. The dihedral angle between the two phenyl rings bonded to the hydrazine group is 86.45 (13)°. The furan ring makes dihedral angles of 3.4 (2) and 7.06 (13)°, respectively, with the methyl-idenehydrazine C=N-N plane and the benzene ring.

  9. Quantitative and qualitative analysis of DNA methylation at N3-adenine by N-methyl-N-nitrosourea.

    PubMed

    Kelly, J D; Shah, D; Chen, F X; Wurdeman, R; Gold, B

    1998-12-01

    The sequence-specific alkylation of DNA by N-methyl-N-nitrosourea (MNU) has been demonstrated for the minor groove N3-methyladenine (N3-MeAde) adduct using neutral thermal hydrolysis and polyacrylamide sequencing gels. The ratio of relative yields of N7- and N3-MeAde and N7-methylguanine (N7-MeGua) is approximately 0.03:0. 15:1.00, respectively, on the basis of the gel data, and these values are comparable to relative yields determined by bulk digestion of MNU-methylated DNA when HPLC was used to analyze the individual adducts. In contrast to the methylation at N7-guanine (N7-Gua) by MNU, alkylation at Ade shows minimal sequence selectivity. Similar to the methylation at N7-Gua, formation of N3-MeAde by MNU is inhibited by 50-200 mM concentrations of NaCl and DNA binding cations, including distamycin and spermine. However, N3-MeAde formation at Ade residues within methidiumpropyl-EDTA-Fe(II) footprinted distamycin DNA affinity binding regions is selectively inhibited at low concentrations of distamycin relative to Ade sites outside of ligand binding regions, and N7-Gua within or outside the distamycin binding regions. HPLC analysis shows that distamycin also quantitatively inhibits the production of N3-methylguanine when calf thymus DNA is treated with MNU or methyl methanesulfonate. The specific inhibitory effect of distamycin, which binds in the minor groove at Ade/Thy-rich sequences, provides additional evidence that the predominant DNA lesion detected at Ade by sequencing gel analysis involves minor groove N3-MeAde modifications.

  10. Disorder in large- N theories

    NASA Astrophysics Data System (ADS)

    Aharony, Ofer; Komargodski, Zohar; Yankielowicz, Shimon

    2016-04-01

    We consider Euclidean Conformal Field Theories perturbed by quenched disorder, namely by random fluctuations in their couplings. Such theories are relevant for second-order phase transitions in the presence of impurities or other forms of disorder. Theories with quenched disorder often flow to new fixed points of the renormalization group. We begin with disorder in free field theories. Imry and Ma showed that disordered free fields can only exist for d > 4. For d > 4 we show that disorder leads to new fixed points which are not scale-invariant. We then move on to large- N theories (vector models or gauge theories in the `t Hooft limit). We compute exactly the beta function for the disorder, and the correlation functions of the disordered theory. We generalize the results of Imry and Ma by showing that such disordered theories exist only when disorder couples to operators of dimension Δ > d/4. Sometimes the disordered fixed points are not scale-invariant, and in other cases they have unconventional dependence on the disorder, including non-trivial effects due to irrelevant operators. Holography maps disorder in conformal theories to stochastic differential equations in a higher dimensional space. We use this dictionary to reproduce our field theory results. We also study the leading 1 /N corrections, both by field theory methods and by holography. These corrections are particularly important when disorder scales with the number of degrees of freedom.

  11. Optical spectra of protected diamine 10-bond-bridged intervalence radical cations related to N,N,N'N'-tetraalkylbenzidine.

    PubMed

    Nelsen, Stephen F; Luo, Yun; Weaver, Michael N; Lockard, Jenny V; Zink, Jeffrey I

    2006-05-26

    The optical absorption spectra of the delocalized intervalence radical cations of seven o,o'-linked benzidine derivatives that have the nitrogens protected as 9-(9-aza-bicyclo[3.3.1]nonan-3-one) derivatives are discussed and compared with that of the p-phenylene radical cation. The linking units are CH2, CH2CH2, NMe, S, SO2, and C=O, and we also studied H,H (the unlinked benzidine). The lowest-energy absorption band is assigned as the transition from the antibonding combination of symmetrical N and aromatic orbitals to the antibonding combination of the antisymmetric N and aromatic orbitals using TD-DFT calculations, and a good correlation between the observed transition energies and those calculated using the simple Koopmans theorem-based "neutral in-cation geometry" calculations on the UB3LYP/6-31G* structures is found. The use of the two-state model that equates the electronic interaction through the bridge between the amino groups with half of the lowest transition energy is seriously incorrect for these and other delocalized intervalence compounds. The problem of extracting the electronic interactions that actually are involved from calculated transition energies is discussed.

  12. WH(n) under pressure.

    PubMed

    Zaleski-Ejgierd, Patryk; Labet, Vanessa; Strobel, Timothy A; Hoffmann, Roald; Ashcroft, N W

    2012-04-18

    An initial observation of the formation of WH under pressure from W gaskets surrounding hydrogen in diamond anvil cells led to a theoretical study of tungsten hydride phases. At P = 1 atm no stoichiometry is found to be stable with respect to separation into the elements, but as the pressure is raised WH(n) (n = 1-6, 8) stoichiometries are metastable or stable. WH and WH(4) are calculated to be stable at P > 15 GPa, WH(2) becomes stable at P > 100 GPa and WH(6) at P > 150 GPa. In agreement with experiment, the structure computed for WH is anti-NiAs. WH(2) shares with WH a hexagonal arrangement of tungsten atoms, with hydrogen atoms occupying octahedral and tetrahedral holes. For WH(4) the W atoms are in a distorted fcc arrangement. As the number of hydrogens rises, the coordination of W by H increases correspondingly, leading to a twelve-coordinated W in WH(6). In WH(8) H(2) units also develop. All of the hydrides considered should be metallic at high pressure, though the Fermi levels of WH(4) and WH(6) lie in a deep pseudogap. Prodded by these theoretical studies, experiments were then undertaken to seek phases other than WH, exploring a variety of experimental conditions that would favor further reaction. Though a better preparation and characterization of WH resulted, no higher hydrides have as yet been found.

  13. Twisting the N=2 string

    NASA Astrophysics Data System (ADS)

    Ketov, Sergei V.; Lechtenfeld, Olaf; Parkes, Andrew J.

    1995-03-01

    The most general homogeneous monodromy conditions in N=2 string theory are classified in terms of the conjugacy classes of the global symmetry group U(1,1)⊗openZ2. For classes which generate a discrete subgroup Γ, the corresponding target space backgrounds openC1,1/Γ include half spaces, complex orbifolds, and tori. We propose a generalization of the intercept formula to matrix-valued twists, but find massless physical states only for Γ=open1 (untwisted) and Γ=openZ2 (in the manner of Mathur and Mukhi), as well as for Γ being a parabolic element of U(1,1). In particular, the 16 openZ2-twisted sectors of the N=2 string are investigated, and the corresponding ground states are identified via bosonization and BRST cohomology. We find enough room for an extended multiplet of ``spacetime'' supersymmetry, with the number of supersymmetries being dependent on global ``spacetime'' topology. However, world-sheet locality for the chiral vertex operators does not permit interactions among all massless ``spacetime'' fermions.

  14. Coating MCPs with AlN and GaN

    NASA Technical Reports Server (NTRS)

    Bensaoula, Abdelhakim; Starikov, David; Boney, Chris

    2006-01-01

    A development effort underway at the time of reporting the information for this article is devoted to increasing the sensitivity of microchannel plates (MCPs) as detectors of photons and ions by coating the MCPs with nitrides of elements in period III of the periodic table. Conventional MCPs are relatively insensitive to slowly moving, large-mass ions for example, ions of biomolecules under analysis in mass spectrometers. The idea underlying this development is to coat an MCP to reduce its work function (decrease its electron affinity) in order to increase both (1) the emission of electrons in response to impingement of low-energy, large-mass ions and (2) the multiplying effect of secondary electron emission. Of particular interest as coating materials having appropriately low or even negative electron affinities are gallium nitride, aluminum nitride, and ternary alloys of general composition Al(x)Ga(1-x)N (where 0N and GaN both undoped and doped with Si were deposited on commercial MCPs by radio-frequency molecular-beam epitaxy (also known as plasma-assisted molecular-beam epitaxy) at temperatures <200 C. This deposition technique is particularly suitable because (1) MCPs cannot withstand the higher deposition-substrate temperatures used to decompose constituent compounds in some other deposition techniques and (2) in this technique, the constituent Al, Ga, and N

  15. Discriminative Stimulus Effects of N,N-Diisopropyltryptamine

    PubMed Central

    Carbonaro, Theresa M.; Forster, Michael J.; Gatch, Michael B.

    2012-01-01

    Rationale Serotonergic hallucinogens such as (+)-lysergic acid diethylamide (LSD) and dimethyltryptamine (DMT) produce distinctive visual effects, whereas the synthetic hallucinogen N,N-diisopropyltryptamine (DiPT) is known for its production of auditory distortions. Objective: This study compares the discriminative stimulus effects of DiPT to those of visual hallucinogens. Methods Adult male rats were trained to discriminate DiPT (5 mg/kg, 15 min) from saline under a FR10 schedule. A dose-effect and time course of DiPT’s discriminative stimulus effects were established. DMT, (−)-2,5-dimethoxy-4-methylamphetamine (DOM), LSD, (±)-methylenedioxymethamphetamine (MDMA) and (+)-methamphetamine were tested for cross-substitution in DiPT-trained animals. Results Rats learned to discriminate DiPT from saline in an average of 60 training sessions (30 drug and 30 saline). DiPT (0.5 – 5 mg/kg) produced dose-dependent increases in drug-appropriate responding (DAR) to 99% (ED50 = 2.47 mg/kg). Onset of the discriminative stimulus effects was within 5 minutes and the effects dissipated within 4 hours. Full substitution for the discriminative stimulus effects of DiPT occurred with LSD, DOM and MDMA. DMT only partially substituted for DiPT (65% DAR), whereas (+)-methamphetamine failed to substitute for DiPT (29% DAR). Conclusions The discriminative stimulus effects of DiPT were similar those of a number of synthetic hallucinogens, only partially similar to those of DMT, but not similar to (+)-methamphetamine. The putative DiPT-induced auditory distortions do not lead to discriminative stimulus effects distinguishable from other hallucinogens. PMID:23070023

  16. Climate-Dependence of Plant-Soil 15N/14N Interactions Across Tropical Rainforests

    NASA Astrophysics Data System (ADS)

    Houlton, B. Z.; Sigman, D. M.; Hedin, L. O.

    2005-12-01

    In most areas of the world, the 15N/14N of bulk soils is higher than that of plant leaves, and the isotopic signatures of these two ecosystem N pools progressively diverge with increasing rainfall. However, both the cause for this isotopic trend and its implications for understanding interactions between climate and N cycles are largely unknown. We report 15N/14N measurements of nitrate, ammonium, and total dissolved N in soil extracts from a highly constrained rainfall sequence in Hawaii, across which this trend in ecosystem 15N/14N is captured, to examine the competing explanations for plant-soil 15N/14N uncouplings. While the isotopic influences of microbial transfers of N between nitrate and ammonium pools and plant-mycorrhizae interactions have been posited in plant-soil 15N/14N relationships, our data did not support an important role for either of these mechanisms. Instead, preferential regeneration of 14N during the breakdown of DON to ammonium explains why the 15N/14N of plants is lower than that of bulk soils. Fractionation at this step leads to two isotopically distinct N subcycles in each forest, a lower-15N/14N subcycle composed of ammonium, nitrate, and bulk plant biomass N that `spins' rapidly and a higher-15N/14N subcycle composed of bulk soil N and DON that is much less dynamic. The increased difference between soil and plant 15N/14N is due to changes in the impacts of nitrification and denitrification on the 15N/14N of ammonium and nitrate, coupled with a switch from nitrate to ammonium uptake by plants under the wettest conditions. For instance, the particularly large (~6 per mil) 15N/14N difference between plants and soils in the wettest sites is due to the lack of 15N-enrichment of ammonium by nitrification coupled with plant dependence on ammonium uptake only. Our results highlight the importance of interactions between DON breakdown, ecosystem N recycling, and gaseous N losses in the explaining the interactions between the 15N signatures of

  17. Binding of benzidine, N-acetylbenzidine, N, N'-diacetylbenzidine and Direct Blue 6 to rat liver DNA.

    PubMed Central

    Martin, C N; Beland, F A; Kennelly, J C; Kadlubar, F F

    1983-01-01

    Studies were performed to assess covalent binding of [3H]benzidine, [14C]N-acetylbenzidine, [14C]N, N'-diacetylbenzidine, and the benzidine-derived azo dye Direct Blue 6 to rat hepatic DNA. Following IP injection into male Sprague-Dawley rats, benzidine and N-acetylbenzidine bound to liver DNA to yield the same adduct: N-(deoxyguanosin-8-yl)-N'-acetylbenzidine. The isomeric N-(deoxyguanosin-8-yl)-N-acetylbenzidine and the deacetylated adduct N-(deoxyguanosin-8-yl) benzidine were also synthesized, but neither of these adducts was detected in vivo. Injection of N,N'-diacetylbenzidine resulted in only barely detectable binding which was insufficient for adduct analysis. [3H]Direct Blue 6 was administered to male Wistar rats either by IP injection or by gavage. In both instances, Direct Blue 6 bound covalently to liver DNA; however, binding occurred at a much higher level in the IP injected animals. With IP injected animals, high pressure liquid chromatographic analysis indicated that approximately 70% of the radioactivity was associated with N-(deoxyguanosin-8-yl) benzidine. PMID:6832087

  18. 15N Abundance of Nodules as an Indicator of N Metabolism in N2-Fixing Plants 1

    PubMed Central

    Shearer, Georgia; Feldman, Lori; Bryan, Barbara A.; Skeeters, Jerri L.; Kohl, Daniel H.; Amarger, Nöelle; Mariotti, Françoise; Mariotti, André

    1982-01-01

    This paper expands upon previous reports of 15N elevation in nodules (compared to other tissues) of N2-fixing plants. N2-Fixing nodules of Glycine max (soybeans), Vigna unguiculata (cowpea), Phaseolus vulgaris (common bean), Phaseolus coccineus (scarlet runner bean), Prosopis glandulosa (mesquite), and Olneya tesota (desert ironwood) were enriched in 15N. Nodules of Vicia faba (fava beans), Arachis hypogaea (peanut), Trifolium pratense (red clover), Pisum sativum (pea), Lathyrus sativus (grass pea), Medicago sativa (alfalfa), and Lupinus mutabilis (South American lupine) were not; nor were the nodules of nine species of N2-fixing nonlegumes. The nitrogen of ineffective nodules of soybeans and cowpeas was not enriched in 15N. Thus, 15N elevation in nodules of these plants depends on active N2-fixation. Results obtained so far on the generality of 15N enrichment in N2-fixing nodules suggest that only the nodules of plants which actively fix N2 and which transport allantoin or allantoic acid exhibit 15N enrichment. PMID:16662517

  19. Energy relaxation of hot electrons in lattice-matched AlInN/AlN/GaN heterostructures

    SciTech Connect

    Zhang, J.-Z.; Dyson, A.; Ridley, B. K.

    2013-12-04

    Using the dielectric continuum model, hot-electron power dissipation and energy relaxation times are calculated for a typical lattice-matched AlInN/AlN/GaN heterostructure, including effects of hot phonons and screening from the mobile electrons. The calculated power dissipation and energy relaxation times are very close to the experimental data.

  20. Large-N solution of the heterotic N=(0,1) two-dimensional O(N) sigma model

    SciTech Connect

    Koroteev, Peter; Monin, Alexander

    2010-05-15

    In this paper we build a family of heterotic deformations of the O(N) sigma model. These deformations break (1,1) supersymmetry down to (0,1) symmetry. We solve this model at large N. We also find an alternative superfield formulation of the heterotic CP{sup N} sigma model, which was discussed in the literature before.

  1. In situ stress measurements during MOCVD growth of thick N-polar InGaN

    NASA Astrophysics Data System (ADS)

    Al Balushi, Zakaria Y.; Redwing, Joan M.

    2017-08-01

    The growth of N-polar InGaN films by metalorganic chemical vapor deposition (MOCVD) on N-polar GaN was investigated in order to understand the evolution of growth stress and the dislocation microstructure of relatively thick InGaN films (140 nm) in the absence of hexagonal hillocks and V-pits, which are typically present in III-polar InGaN. During in situ stress measurements of N-polar InGaN, growth initiates under an initial low stress state, which gradually transitions to a constant compressive incremental stress for the remainder of the film thickness. This behavior in the growth stress evolution in N-polar InGaN occurs regardless of the stress state of the GaN base layer (i.e., compression or tension), which was controlled by varying the temperature of the initial low temperature layer in a two-step temperature growth process for N-polar GaN. A blue shift in the PL peak emission of N-polar InGaN was, however, observed with increasing incremental compressive stress in the N-polar GaN base layer. These results provide insight into potential mechanisms of plastic relaxation in high crystal quality thick N-polar InGaN films grown by MOCVD.

  2. Dynamical coupled-channels study of {pi}N {right arrow} {pi pi}N reactions.

    SciTech Connect

    Kamano, H.; Julia-Diaz, B.; Lee, T.-S. H.; Matsuyama, A.; Sato, T.; Physics; Jefferson Lab.; Univ. of Barcelona; Shizuoka Univ.; Osaka Univ.

    2009-02-24

    As a step toward performing a complete coupled-channels analysis of the world data of {pi}N,{gamma}*N {yields} {pi}N,{eta}N,{pi}{pi}N reactions, the {pi}N {yields} {pi}{pi}N reactions are investigated starting with the dynamical coupled-channels model developed in Phys. Rev. C 76, 065201 (2007). The channels included are {pi}N,{eta}N, and {pi}{pi}N which has {pi}{Delta},{rho}N, and {sigma}N resonant components. The nonresonant amplitudes are generated from solving a set of coupled-channels equations with the meson-baryon potentials defined by effective Lagrangians. The resonant amplitudes are generated from 16 bare excited nucleon (N*) states that are dressed by the nonresonant interactions as constrained by the unitarity condition. The data of total cross sections and {pi}N and {pi}{pi} invariant mass distributions of {pi} + p {yields} {pi} + {pi} + n, {pi} + {pi}0p and {pi} - p {yields} {pi} + {pi} - n, {pi} - {pi}0p,{pi}0{pi}0n reactions from threshold to the invariant mass W = 2 GeV can be described to a very large extent. We show the importance of the coupled-channels effects and the strong interference among the contributions from the {pi}{Delta},{sigma}N, and {rho}N channels. The large interference between the resonant and nonresonant amplitudes is also demonstrated. Possible future developments are discussed.

  3. Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine).

    PubMed

    Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G

    2015-06-07

    Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm(-1) region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ∼0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters.

  4. Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

    NASA Astrophysics Data System (ADS)

    Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

    2015-06-01

    Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm-1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ˜0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters.

  5. Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

    PubMed Central

    Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

    2015-01-01

    Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm−1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ∼0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters. PMID:26049458

  6. A high-performance liquid chromatography method for determination 2-(n-(N,N,N-trimethyl)-n-alkyl)-5-alkylfuryl halides in dipalmitoylphosphatidilcholine liposome solutions.

    PubMed

    Morales, Javier; Zanocco, Antonio L; Günther, Germán; Lemp, Else

    2006-08-25

    A high-performance liquid chromatography (HPLC) method for the determination of 2-(4-(N,N,N-trimethyl)-butyl)-5-dodecylfuryl bromide (DFTA) in dipalmitoylphophatidil-choline (DPPC) liposome solutions has been developed. Lipid-soluble furan derivatives, 2,5-disubstituted with different n-alkyl chains and a terminal trimethylammonium group are useful probes for studying singlet oxygen dynamics and equilibria in microcompartmentalized systems. The actual HPLC method uses a gradient elution and DAD detection. The chromatographic separation of these components is achieved using a C18 analytical column with a 10mM solution of 1-heptanesulfonic acid (PIC-7)-methanol (10:90, v/v) as initial mobile phase. Both DFTA peaks are well resolved and free of interference from matrix components and reaction products. The method has been found to be linear (r > 0.999) over a wide concentration range and reliable to perform kinetic experiments in which the time dependent consumption of a tetraalkylammonium surfactant in a microorganized systems composed by lipidic surfactants is followed.

  7. Electrochemical impedance spectroscopy of metal alloys in the space transportation system launch environment

    NASA Technical Reports Server (NTRS)

    Calle, Luz

    1990-01-01

    AC impedance measurements were performed to investigate the corrosion resistance of 18 alloys under conditions similar to the Space Transportation System (STS) launch environment. The alloys were: (1) zirconium 702; (2) Hastelloy C-22, C-276, C-4, and B-2; (3) Inconel 600 and 825; (4) Ferralium 255; (5) Inco Alloy G-3; (6) 20Cb-3; (7) SS 904L, 304LN, 316L, 317L, and 304L; (8) ES 2205; and (9) Monel 400. AC impedance data were gathered for each alloy at various immersion times in 3.55 percent NaCl-0.1N HCl. Polarization resistance values were obtained for the Nyguist plots at each immersion time using the EQUIVALENT CIRCUIT software package available with the 388 electrochemical impedance software. Hastelloy C-22 showed the highest overall values for polarization resistance while Monel 400 and Inconel 600 had the lowest overall values. There was good general correlation between the corrosion performance of the alloys at the beach corrosion testing site, and the expected rate of corrosion as predicted based on the polarization resistance values obtained. The data indicate that electrochemical impedance spectroscopy can be used to predict the corrosion performance of metal alloys.

  8. Sylvanus Albert Reed Award: Eastman N. Jacobs

    NASA Technical Reports Server (NTRS)

    1937-01-01

    Sylvanus Albert Reed Award - Eastman N. Jacobs: In 1937, Eastman N. Jacobs, one of Langley's most adventurous researchers, received the Sylvanus Albert Reed Award for his contributions to the aerodynamic improvement of airfoils.

  9. Cone Penetrometer N Factor Determination Testing Results

    SciTech Connect

    Follett, Jordan R.

    2014-03-05

    This document contains the results of testing activities to determine the empirical 'N Factor' for the cone penetrometer in kaolin clay simulant. The N Factor is used to releate resistance measurements taken with the cone penetrometer to shear strength.

  10. Alloys For Flexible Hoses In A Corrosive Environment

    NASA Technical Reports Server (NTRS)

    Macdowell, Louis G., III; Ontiveros, Cordelia

    1992-01-01

    High-nickel alloy resists pitting corrosion. Report evaluates metal alloys for flexible hoses in corrosive environment. Tested to find alternatives to 304L stainless steel. Nineteen alloys selected for testing on basis of reputation for resistance to corrosion. Top five, in order of decreasing resistance to corrosion: Hastelloy(R) C-22, Inconel(R) 625, Hastelloy(R) C-276, Hastelloy(R) C-4, and Inco(R) alloy G-3. Of these, Hastelloy(R) C-22 found best for flexible-hose application.

  11. GaN and AlGaN/GaN heterostructures grown on two dimensional BN templates

    NASA Astrophysics Data System (ADS)

    Snure, Michael; Siegel, Gene; Look, David C.; Paduano, Qing

    2017-04-01

    Two dimension materials, like BN and graphene, have been shown to be excellent templates for the growth and fabrication of freestanding III-nitride materials. In this paper we study the effects of BN morphology on GaN and AlGaN/GaN heterostructures grown on these templates. The crystallinity, transport, and optical properties of the GaN layer are examined and found to be well correlated to the BN template. The self-separation of GaN from the BN/sapphire template is also connected to morphology, resulting in freestanding GaN layers. Transport properties of Si doped GaN and AlGaN/GaN heterostructures were examined for different BN templates. The bulk GaN mobility was closely linked to the morphology of the BN template resulting in room temperature mobility from 395 to 520 cm2/Vs. The range in 3D mobility can be linked to increased dislocation densities in GaN grown on rougher BN templates. High 2DEG mobility ( 2000 cm2/Vs at 300 K) is achieved in AlGaN/GaN grown on atomically smooth BN templates, with a sheet electron density of 1×1013 cm-2, comparable to values obtained on conventional substrates. Samples grown on BN/sapphire showed mobilities (at 9 K) from 33000 cm2/Vs to 15200 cm2/Vs depending on BN roughness. The differences are associated with variations in AlGaN/GaN interface-roughness scattering and dislocation density due to the BN template morphology.

  12. Low-n-6 and low-n-6 plus high-n-3 diets for use in clinical research

    PubMed Central

    MacIntosh, Beth A.; Ramsden, Christopher E.; Faurot, Keturah R.; Zamora, Daisy; Mangan, Margaret; Hibbeln, Joseph R.; Mann, J. Douglas

    2014-01-01

    Few trials have evaluated the metabolic effects and health outcomes of lowering dietary n-6 PUFA. The objectives of the present paper were (1) to report the methods employed to lower dietary n-6 PUFA, while either increasing or maintaining n-3 PUFA intake and (2) to validate our methods with 24 h recalls and erythrocyte fatty acid analyses. A total of sixty-seven subjects were randomised to either (1) an average-n-3 PUFA, low-n-6 PUFA (L6) intervention designed to lower linoleic acid (LA; ≤2·5 % of energy (en%)) and arachidonic acid (≤60 mg/d), while maintaining an average US intake of n-3 PUFA or (2) a high-n-3 PUFA, low-n-6 PUFA (H3-L6) intervention designed to lower n-6 LA, while increasing the n-3 PUFA α-linolenic acid (ALA; ≥1·5 en%) and EPA + DHA (≥1000 mg/d). Pre- and intra-intervention nutrient intakes were estimated with six 24 h dietary recalls per subject. Both groups achieved the targeted reductions in dietary LA to ≤2·5 en% (median LA 2·45 (2·1, 3·1); P<0·001). Intakes of n-3 PUFA did not change for the L6 group. Target increases in n-3 ALA (median 1·6 en%, (1·3, 2·0), P<0·001) and EPA + DHA (1482 mg, (374, 2558), P<0·001) were achieved in the H3-L6 group. Dietary changes were validated by corresponding changes in erythrocyte n-6 and n-3 fatty acid composition. Dietary LA can be lowered to ≤2·5 en%, with or without concurrent increases in dietary n-3 PUFA, in an outpatient clinical trial setting using this integrated diet method. PMID:23328113

  13. Asymmetric Induction by a Nitrogen 14N/15N Isotopomer in Conjunction with Asymmetric Autocatalysis

    PubMed Central

    Ozaki, Hanae; Harada, Shunya; Tada, Kyohei; Ayugase, Tomohiro; Ozawa, Hitomi; Kawasaki, Tsuneomi

    2016-01-01

    Abstract Chirality arising from isotope substitution, especially with atoms heavier than the hydrogen isotopes, is usually not considered a source of chirality in a chemical reaction. An N 2 ,N 2 ,N 3 ,N 3‐tetramethyl‐2,3‐butanediamine containing nitrogen (14N/15N) isotope chirality was synthesized and it was revealed that this isotopically chiral diamine compound acts as a chiral initiator for asymmetric autocatalysis. PMID:27754589

  14. Growth in the global N2 sink attributed to N fertilizer inputs over 1860 to 2000.

    PubMed

    Wang, Chao; Houlton, Benjamin Z; Dai, Weiwei; Bai, Edith

    2017-01-01

    Cropland expansion and fertilizer applications are among the most important substantial effects of human actions on the global nitrogen (N) cycle. However, questions remain over the fate of anthropogenic N inputs, particularly whether a significant fraction of N-based fertilizers have been lost to inert N2 or reactive N forms. Here, we combine natural N isotope constraints on the pre-industrial N cycle with global mass-balance modeling to investigate the role of cropland conversion on gaseous N emissions and hydrological N leaching fluxes. We estimate that cropland expansion has been accompanied by >9-fold increase in N input rates to cropping systems, roughly doubling the baseline N budget of the terrestrial biosphere. As a consequence, approximately 10 times more N is exported from modern croplands to the hydrosphere than in 1860, with a five-fold increase in cropland N gases emission to the atmosphere. Atmospheric NH3, NO, N2O and N2 fluxes increased from 8.6, 16.6, 11.7 and 31.9TgNyr(-1), respectively, in 1860 to 17.7, 23.6, 15.2 and 39.7TgNyr(-1), respectively, by 2000. Thus, the growth in N2 accounted for ~20% of cropland-driven N losses (dissolved plus gaseous pathways), with the remaining 80% exported as reactive N forms. Although the increase in N2 emissions has mitigated some of the unwanted side-effects of N fertilizer applications on human health, the economy, and climate change, this inert sink has been unable to keep pace with the increase in N inputs for enhanced food production. Our results imply that, unless new management steps are taken, an increasing fraction of N fertilizers will mobilize to reactive N forms in the global land, air and water systems, thus further accelerating the negative consequences of human modifications of the N cycle this century. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Terahertz-frequency InN/GaN heterostructure-barrier varactor diodes

    NASA Astrophysics Data System (ADS)

    Reklaitis, A.

    2008-09-01

    Frequency multipliers based on the single-barrier and double-barrier InN/GaN heterostructure varactor diodes are suggested. The DC and large-signal AC vertical electron transport in the InN/GaN diodes are investigated by ensemble Monte Carlo simulations. It is found that InN/GaN heterostructure-barrier varactor diodes are able to operate as efficient frequency multipliers in the frequency range up to 1 THz.

  16. 40 CFR 721.10173 - Silanamine,1,1,1-triethoxy-N,N-diethyl-.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Silanamine,1,1,1-triethoxy-N,N-diethyl... Specific Chemical Substances § 721.10173 Silanamine,1,1,1-triethoxy-N,N-diethyl-. (a) Chemical substance...,1-triethoxy-N,N-diethyl- (PMN P-03-793; CAS No. 35077-00-0) is subject to reporting under this...

  17. 40 CFR 721.10173 - Silanamine,1,1,1-triethoxy-N,N-diethyl-.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Silanamine,1,1,1-triethoxy-N,N-diethyl... Specific Chemical Substances § 721.10173 Silanamine,1,1,1-triethoxy-N,N-diethyl-. (a) Chemical substance...,1-triethoxy-N,N-diethyl- (PMN P-03-793; CAS No. 35077-00-0) is subject to reporting under this...

  18. 40 CFR 721.10173 - Silanamine,1,1,1-triethoxy-N,N-diethyl-.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Silanamine,1,1,1-triethoxy-N,N-diethyl... Specific Chemical Substances § 721.10173 Silanamine,1,1,1-triethoxy-N,N-diethyl-. (a) Chemical substance...,1-triethoxy-N,N-diethyl- (PMN P-03-793; CAS No. 35077-00-0) is subject to reporting under this...

  19. Octanol-water partition coefficients of substituted alpha, N-diphenylnitrones and benzonitrile N-oxides

    SciTech Connect

    Kirchner, J.J.; Acree, W.E. Jr.; Leo, A.J.; Gelli, G.

    1985-10-01

    Experimental octanol-water partition coefficients are reported for substituted alpha, N-diphenylnitrones and benzonitrile N-oxides. The results of these measurements are used to calculate the aromatic fragment constants pi HC = N(O)C6H5, pi C = N----O, fHC = N(O), and fC = N----O for the group contribution methods of Hansch and Leo.

  20. Asymmetric Induction by a Nitrogen (14) N/(15) N Isotopomer in Conjunction with Asymmetric Autocatalysis.

    PubMed

    Matsumoto, Arimasa; Ozaki, Hanae; Harada, Shunya; Tada, Kyohei; Ayugase, Tomohiro; Ozawa, Hitomi; Kawasaki, Tsuneomi; Soai, Kenso

    2016-12-05

    Chirality arising from isotope substitution, especially with atoms heavier than the hydrogen isotopes, is usually not considered a source of chirality in a chemical reaction. An N(2) ,N(2) ,N(3) ,N(3) -tetramethyl-2,3-butanediamine containing nitrogen ((14) N/(15) N) isotope chirality was synthesized and it was revealed that this isotopically chiral diamine compound acts as a chiral initiator for asymmetric autocatalysis.